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529 Cards in this Set

  • Front
  • Back
How much liver function must be lost before clinical signs or abnormal bloodwork is seen?
80%
In the horse, which liver enzyme is highly specific for hepatocellular damage?
SDH (sorbitol dehydrogenase)
With cellular injury, SDH is released from where?
Cytoplasm of hepatocyte
AST is a non-specific liver enzyme since it is also present where in the equine?
Liver, skeletal and cardiac muscle, RBC
AST can be falsely increased with what conditions?
Hemolysis and lipemia
ALP is an enzyme that is indicative of what?
Biliary obstruction of cholestasis
ALP can also be elevated with what condition?
Neonates with osteoblastic activity
In horses, which enzyme is the most sensitive indicator of liver disease?
GGT
GGT is an indicator of what liver condition?
Biliary tract disease or cholestasis
What do young animals have higher GGT?
Colostral ingestion
Is bilirubin a sensitive indicator of liver dz in the horse?
No
In the liver, free or indirect bilirubin is conjugated with what?
glucose
Direct (conjugated) bilirubin should be how much of total bilirubin?
< 25% of the total
What other condition can cause hyperbilirubinemia?
Anorexia, fasting
In fasting hyperbilirubinemia, which portion of bilirubin is elevated?
Indirect (unconjugated)
What does elevated bile acids indicate?
Only that hepatobiliary function is abnormal
When performing a bile acid test, which sample is not needed?
Fasting
What is the benefit of measuring bile acids in a horse?
More sensitive of liver dz than bilirubin
Why would you measure blood ammonia?
Failure of the liver to process ammonia into urea may result from chronic hepatocellular dz leading to hyperammonia (and hepatocencephalopathy)
What other 2 heaptic products will decrease with liver dysfunction?
BUN, coagulation factors (7, ext pathway PT)
On U/S, the liver should remain within what boundary?
Costochondral junctions
What structures of the lover can be seen with endoscopy?
Distal portion of common bile duct only
What is the benefit of performing a liver bx?
Provides definitive dx and allows the clinician top offer a prognosis
In which pts should a liver bx be performed with extra caution?
Clinical bleeding diatheses
What are the indicators for a poor prognosis in a horse with liver dz?
-hypoalbuminemia <2.5g/dl
-increased globulin level
-prolonged PT by 30%
-chronic severe elevation of GGT
-bridging fibrosis of liver lobules on histopath
What are the terminal clinical signs in a horse with a fibrotic liver?
Hemolytic crisis and marked hepatoencephalopathy
What is the most classic sign of liver dz?
Icterus- oral mucus membranes, sclera, aural/vaginal mucosa
What causes icterus?
Failure to excrete bilirubin
In horses, what condition can cause jaundice without primary liver dysfunction?
Anorexic hyperbilirubinemia
What are the clinical signs of hepatic encephalopathy?
-anbnormal mentation, cortical dysfunction
-alterations in behavior
-wandering aimlessly
-circling/head pressing
-inspiratory stertor
-yawning
What is the cause of dermatitis/photosensitization with liver disease?
Failure of the liver to excrete phylloerthrin, is transported to the skin, reacts with UV light
Why is diarrhea a sign of liver dysfunction?
Failure of the liver to recirculate bile acids leads to poor digestion of fat and subsequent diarrhea
Failures of the liver to metabolize carbs, fats and proteins leads to what clinical signs of liver failure?
Lethargy/wt loss
Why is peripheral edema a sign of liver dz?
Liver fails to produce the primary plasma protein albumin, oncotic pressure drops, allowing fluid to leak into the interstitium leading to edema
What is the cause of ascites in liver patients?
Portal hypertension and increased hydrostatic pressure along the sinusoidal channels increase lymph production- lymph is high in protein and leaks to the peritoneum and then the peritoneal cavity
Bleeding diatheses is a result of the liver failing to produce which clotting factors?
2, 7, 9, 10
Horses with what type of acute liver failure have a better chance for long-term regeneration of the liver?
Those with no evidence of chronic fibrosis
CNS dysfunction is most likely due to what?
Abnormal protein metabolism by the liver
From the abnormal protein metabolism, levels of what chemical rise in the blood?
Ammonia
What is the goal of initial tx for HE?
-abolishing the abnormal behaviors to prevent the horse for endangering itself and others
Which class of drugs should be avoided in cases of HE, and why?
Avoid benzodiazepines, effects of GABA on inhibitory neurons may worsen signs of HE
What is the drug of choice to use as a sedative for a horse with HE?
Detomidine- a2 agonist
Is neomycin a good choice for a drug that will minimize the amount of ammonia in the system?
Only initially, prolonged use may be toxic to intestinal enterocytes
Why is the administration of dextrose important, esp since most horses in liver failure aren’t hypoglycemic?
-provides PPN is horse is anorexic
-decreases ammonia concentration in blood
-decreases reliance of catabolic gluconeogenesis
-decreases protein catabolism
-spares hepatic energy used in gluconeogenesis
Blood glucose should be maintained at what level for a horse?
80-120 mg/dl
Horses with liver should consume a diet comprised of what components?
-branched chain amino acids
-very low protein fiber
-oats and grass hay, avoid alfalfa
Horses that have chronic active hepatitis may have cholangiohepatitis as well.. these a usually brought on by what type of infection?
Ascending infection, gram neg, from the GI tract
When is the use of abx in a horse with liver disease indicated?
-following liver bx
-histopath results of inflammatory infiltrates
-positive results of bx tissues culture and sensitivity
What are the useful abx in liver patients?
-pcn, gentamycin
-enrofloxicin
-chlorampehincol
-trimethroprim-sulfa
What anti-inflammatory drugs should be given to horses with liver dz?
-Banamine
-pentoxifylline
What is the use of DMSO in liver dz?
May dissolve small biliary stones of sludge within the biliary tract
When would sx be indicted for a liver pt?
When there is obstruction to the distal bile duct and no fibrosis is present
Idiopathic acute hepatitis , the most common cause of acute hepatitis and acute liver failure in horses, is also known as what?
Theiler’s dz
Serum hepatitis
Post-vaccinal hepatitis
IAHD is most often associated with what?
Administration of equine biologic products in adult horses
It has been proposed that IAHD is what type of reactions?
Type III immune mediated
Which clinical sign of liver failure is NOT seen in IAHD?
Fever
Diagnosis of IAHD is largely determined by what?
-anamnesis
-concurrent clinical signs
-abnormalities on serum chem., liver bx, necropsy
Confirmation of IAHD requires what?
Bx or necropsy of the liver
With IAHD, where is the hepatocellular necrosis most severe?
Centrilobar region
What type of tx is used for IAHD?
Supportive
What type of dietary changes are made for tx IAHD?
-low protein
-increase carbs
-branched chain amino acids
In the US, IAHD is associated with what type of horse and why?
Brood mare, use of TAT following parturition
Signs of PA toxicity may be seen when after ingestion?
4 weeks to 1 year
What are the most common clinical signs of PA toxicity?
-weight loss
-slight to moderate icterus
-HE
-photosensitization and diarrhea may occur
-mares may abort
How much of the plant must be ingested to cause toxicity?
2-5% of the horses body weight
What are the common PA plants in the US?
-Senecio (tansy ragwort, groundsel)
-Amsinckia (fiddleneck)
-Crotalaria (rattlebox)
What is the result of ingestion of PAs?
Carried to the liver, metabolized to pyrrole derivatives, can cross link double stranded DNA which inhibits nuclear acids, cell replication and protein synthesis. Hepatocyte unable to divie, becomes enlarged and forms megalocytes
What happens to megalocytes when they die?
Replaced by connective tissue and fibrosis
Hepatocytes located where are first affected by PA toxicosis?
Surrounding portal triads
What is the result of venooclusive dz which disrupts blood supply to the liver?
Regeneration is impossible
Periportal dz from Pas causes which liver enzymes to be persistently elevated?
GGT, ALP
What is the pathognomonic sign of PA toxicosis?
-megalocytes
-biliary hyperplasia
-periportal fibrosis
What is the tx for PA toxicity?
There is none- death occurs within 10 days of clinical signs of liver failure
Which liver enzyme is the most reliable indicator of subclinical PA?
GGT
What are the causes of intrahepatic biliary tract disease?
-cholangitis
-cholelithiasis
-choledocholiththiasis (cbd)
-foreign body
What are the extrahepatic causes of biliary tract disease?
-abscess formation
-inflammatory dz near the CBD
-neoplasia
Which is the most common cause of biliary obstruction in the horse?
Choledocholelithiasis (CBD)
What are bile stones comprised of?
Precipitates or aggregates of biliary components: bilirubin, bile pigments, cholesterol, carboxylic acid, calcium phosphate, sodium taurodeoxycholate
What are the triad of clinical signs of cholelithiasis in a horse?
Colic (intermittent but recurrent, fever, jaundice
What additional signs may be seen?
-HE
-photosensitization
-weight loss
Cholelithiasis should be suspected when direct (conjugated) bilirubin is at what level?
>30% of total bilirubin
What effect does obstruction to flow have on bile acids?
Bile acids are elevated
What other parameters are elevated with cholelithiasis?
-GGT, ALP, AST, SDH,
-neutrophilic leukocytosis
-elevated fibrinogen and globulins
How is cholelithiasis dx?
-abnormal hepatic enzymes
-U/S
What is the appearance of a liver with cholelithiasis?
Echogenicity of the liver parenchyma is increased (comparable to the spleen), bile ducts are tortuous
Hyperlipidemia, hyperlipemia and hypertriglyceridemia are all characterized by what classical clinical signs?
-anorexia
-depression
-lethargy
How would you describe hyperlipidemia?
Mild to moderately elevated serum triglycerides (TGs) with no evidence of lipemic serum or hepatic dysfunction
What is hyperlipemia?
Moderately elevated TGs with milky serum and fatty infiltrates within the liver
Which animals are known for having hyperlipemia?
Ponies, donkeys, miniature horses
What is hypertriglyceridemia?
Mod to severly elevated TG, no evidence of lipemia (no milky serum) and no evidence of fatty liver
What are the risk factors for developing excess circulating TGs?
-mini horse, donkey, pony
-female
-obese animal
-endotoxemia
-enterocolitis
-azotemia
-preg (late)
-lactation
-stress
-anything that predisposes the animal to a negative energy balance
When glycogen stores from the liver are used up, where does energy come from?
Fatty acid oxidation
What triggers the mobilization of fat as energy?
Stress or inability to maintain energy homeostasis
What underlying diseases can trigger fatty oxidation?
-enterocolitis
-endotoxemia
-azotemia
-infection
-parasitism
-neoplasia
-transport
-weaning
Exogneous fat sources are acquired from where?
Dietary intake
How are short chain fatty acids transported to the liver?
Incorporated into phospholipids or TGs by the intestinal epithelium and sent to the liver via portal blood
Larger fatty acids are broken down with the small intestinal lumen by what?
Bile acids- which surround the FAs
What is the role of lipases from the pancreas?
Cleave the bile acid into 2 FFAs and 1 monoglyceride- bile acid continues down SI lumen and is resorbed
What is a micelle?
The 2 FFAs and 1 monoglyceride combine to make a water soluble micelle which is absorbed into the enterocytes (absorbed across the brush border via the unstirred layer)
What happens to the micelle once it is in the endoplasmic reticulum?
Re-esterified into triglycerides with phospholipids, cholesterol and proteins
What are chylomicrons?
The rough ER packages the re-esterified micelles into chylomicrons (water soluble) and expels them into the lateral space (between 2 enterocytes)
How do the chylomicrons get to the liver?
Picked up by the lymphatic circulation, dumped into the vena cava and then into the liver for processing
What is the source of endogenous TGs mobilized for oxidation?
Adipose tissue
Which hormones control the mobilization of adipose tissue?
-glucagon
-norepinephrine
-epinephrine
Once in the liver, what determines the fate of the lipids?
The energy requirements of the animal and the amount of fat and glucose absorbed from the daily diet.
What 5 products can be made by the liver from lipids?
1. Oxidation to acetyl CoAATPenergy
2. Esterification into TGs for storage in the liver
3. Used for gluconeogenesis
4. Made into ketone bodies
5. FFAs used to make TGs that are released into sinusoidal blood as VLDLs
VLDLs are transported to where?
Adipose tissue
What is the rate limiting step of storing VLDLs into adipose tissue?
Lipoprotein lipase (LPL)- activity is stimulated by insulin
True or false…the overproduction of VLDLs by the liver is the cause of hyperlipemia in ponies, mini horses and donkeys?
True
Why is it unlikely for horses to suffer ketoacidosis?
Hepatic efficiency of synthesizing TGs and VLDLs and exporting them back to the bloodstream
What is the effect of hepatic lipidosis?
Fatty infiltrates of the hepatocytes disrupt normal function and may result in hepatic rupture and/or failure
What effect does insulin have on adipose tissue?
Less mobilization of FAs to the liver
Stimulates LDL to remove VLDLs from circulation
What effect do high levels of LPS from endotoxemia have on VLDLs?
Interferes with LPLs ability to removes VLDL from circulation
Hyperlipemia should be considered in any obese pony or donkey with what clinical signs?
-anorexia
-depression
-lethargy
What should you suspect in a horse with decreased attitude and appetite in the face of critical illness?
Hypertriglyceridemia
What is the appearance of serum in the case of hyperlipemia?
Opalescent
What chemistry results would you expect with end stage liver failure?
Decreased glucose, BUN, albumin
The presence of elevated TG’s leads to what vicious cycle?
Inappetance and further elevations in TGs
How can hepatic lipidosis, hyperlipidemia, hyperlipemia/triglyceridemia be resolved?
Assessment and resolution of the underlying disease process
Endotoxemia / enterocolitis resolution
-Pregnant mares may require abortion
-Lactating mares should have foals weaned
Alternate energy sources can be provided by what means?
-enteral
-parenteral
Dextrose CRI
Enteral feeding of 10% of energy reqs
Insulin to counteract hyperglycemia from dextrose
During the PE of the horse, where is the mitral valve located?
Left 5th intercostal space, midway between the shoulder and olecranon
Where is the aortic valve located?
Left 3rd to 4th intercostal space, just below the shoulder
Which valve is located on the left at the 3rd ICS just below the aortic valve?
Pulmonic
How would you localize the tricuspid valve?
On the right at the 4th ICS midway between the shoulder and olecranon
The normal S1 heart sound is caused by what?
Ventricles contract, AV valves close, pulse occurs
What is the cause of the normal S2 heart sound?
Semilunar valves close, diastole
What causes the normal S3 heart sound?
Rapid ventricular filling
How often might you hear S3 in the horse?
50% of horses, often mistaken for a murmur or split heart sound
S4 may be heard in horses and is caused by what?
Atrial contraction
What are non-pathologic murmurs?
Murmurs that occur without organic heart disease
What are some examples of non-pathologic murmurs?
-increased velocity in blood (excitement)
-changes in blood viscosity (anemia or dehydration)
-66% of horses have systolic functional murmurs
-< grade III
-aortic or pulmonic
-most common in neonates
What is the range of the normal resting heartbeat of the horse?
24-44 beats/min
Which heart rhythm is the most common in horses?
Regular sinus rhythm
Which is the most common, non-pathologcal arrhythmia in horses?
2 degree AV block
What are the conditions seen with 2 degree AV block?
-increased vagal tone
-easily eliminated with excitement
-heart rate should remain > 24 bpm
-S4 should be the only sound during block
-confirm with ECG
What block would you suspect if S4 cannot be ascultated
Sinus block (rare in horse)
How is sinus block characterized?
Long pauses in sinus beat/eliminated with exercise
What causes a sinus block?
Increased vagal tone in which SA node does not fire
When is sinus arrhythmia normal?
After exercise
What arrhythmia may be heard in a horse esp. after light exercise, and are considered normal?
Occasional atril or ventricular premature contraction
When is it normal to have 3rd degree complete heart block?
NEVER!
What general clinical signs might be seen in a horse with cardiac disease?
-exercise intolerance
-lethargy or depression
-anorexia or weight loss
A less common sign of heart dz is dependent edema which may be seen with what type of heart dz?
Right heart failure
Where does dependent edema occur?
ventral thorax and abdomen, distal limbs in severe cases
How do you determine edema from inflammation?
edema should by cool , pitting, nonpainful and symmetrical
What general respiratory signs are seen with cardiac dz?
-tachypnea from hypoxia or pulmonary edema
What respiratory sounds might you hear with cardiac dz?
-cough and audible crackles from pulmonary edema with left heart failure
What is a common cause of pulmonary edema in horses?
Ruptured chordae tendinae of the mitral valve
When aucultating the heart, what 3 factors do you consider
-rate
-rhythm
-murmurs
What conditions are you concerned about when assessing heart rate?
-tachycardia and bradycardia (sustained)
When might you be concerned about a normal rhythm with premature contractions?
When the rate is increased or occur more frequently than a few per hour
Pathologic murmurs are associated with what conditions?
-valvular abnormality
-shunts
-altered contractility
-altered blood viscosity
When characterizing a mumur, a systolic murmur is heard when?
Between S1 and S2 (audible during palpation of peripheral pulse)
When is a diastolic murmur heard?
Between S2 and S1
What is meant by a murmur's point of maximum intensity?
Select valve or area where murmur is loudest
The quality of sound of a murmur is subjective without what tool?
A phonogram
Pathologic murmurs are commonly which grade?
>Grade 3
What are the 3 factors useful for determining the cause of a murmur?
-PMI
-Timing
-valvular activity at the time murmur is asculted: is the valve open or closed?
What is a general sign of increased cardiac pressure?
Generalized venous distension
Jugular pulses seen above the lower 1/3 of the neck can be a sign of what type of heart failure?
-tricuspid regurgitation and right heart failure
Jugular pulsations can be confused buy what other pulse?
Referred from carotid artery
Jugular distension without pulsation is a sign of what condition?
Obstruction- thrombosis of jugular vein
Aortic valve insufficiency is often associated with what change in the pulse?
Bounding pulses
Why is an EC the most useful diagnostic tool for rate and rhythm of the horse heart?
Due to large size of equine heart and extensive Purkinje network
In horses, an ECG provides less information regarding what?
heart size
Which lead is used for an ECG of a horse?
1- base lead
How are the ECG leads positioned for a base lead of a horse?
-white lead on right shoulder
-black lead on heart apex
-red lead on neck
-run on lead 1
What normal difference might you see in the P wave of a horse ECG?
Often bipolar and may change configuration
In which direction is the QRS in a base lead ECG of a horse?
usually negative
True or false....in a base lead ECG of a horse, the T is usually positive
true
On an ECG 15 big boxes equals how many seconds?
3
What type of probe is needed to perform echocardiograms?
2.5 MHz
Majority of echo imaging is done on which side of the heart?
Right
What structural info can be gained from an echo?
-size of heart chambers and outflow vessels
-shape of valves
-thickness or walls
-confirm presence of pericarditis or endocarditis
What functional information is gained from an echo?
-motion of walls and valves
-fractional shortening
What is the normal fractional shortening in a large animal?
34-45 %
What does fractional shortening of <25% indicate?
Failure
Serum chemistry might show what results with heart dz?
-azotemia
-increased liver enzymes
Which cardiac enzyme might be increased with mycarditis?
Serum cardiac troponin I
What conditions might a decreased PaO2 indicate?
hypoxemia and shunts
An indirect blood pressure on a horse is taken from where?
Coccygeal artery
When using exercise tests to detect heart disease, normally a the heart and respiratory rates should return to what levels in what timeframe?
Return to within 15% of resting value within 15 minutes of the end of exercise
What technique is used to detect transient or intermittent arrhythmias?
Holter monitor
Pathologic murmurs in horses are of what two types?
-congenital
-acquired
What is the msot common congenital abnormality of the horse?
Interventricular septal defect (VSD)
In which direction does blood flow in the heart with a VSD?
Left to right
VSD leads to what conditions within the circulatory system?
Pulmonary hypertension and left sided overload, may eventually lead to pulmonary edema and left sided failure
What are the clinical size of a larger (>2.5cm) VSD?
-poor growth, exercise intolerance
-pulmonary hypertension and heart failure
-signs develop over days to months
A VSD will produce a > Grade III murmur on what side?
Right
Often there is another murmur, where?
Systolic over the mitral or aortic valve
What tests are used to confirm a VSD?
-Echo
-bubble test or color flow Doppler
What characteristic of a VSD dictates the prognosis?
Size of the defect
What is the course of action it the horse is symptomatic?
Euthanasia
What drugs might be used for medical management of VSD?
-furosemide (Lasix)
-digoxin
What are the components of the tetralogy of Fallot?
-VSD
-aorta displace to right
-pulmonic stenosis
-right ventricular hyperplasia
What are the clinical signs of TOF?
-cyanosis
-poor growth, exercise intolerance in young animals
-right to left shunting of blood across VSD
The right to left shunt through the VSD causes what additional complications?
-obstruction of outflow of right ventricle through the stenotic pulmonary artery
-leads to inadequate oxygenation of blood
How is TOF diagnosed?
-left sided heart base systolic murmur (grade III or >)
-may also be asculted on the right in a young animal
-confirm with 2D echo
What is the prognosis of TOF?
Poor to grave
True or False....PDA is just as common in horses as in small animals
False, no common
usually subclinical
not treated
Are valvular lesions congenital or acquired?
Acquired
Valvular lesions include what types of conditions?
-degenerative changes
-valvular changes
-myocarditis
-endocarditis
-ruptured chordae tendinae
-congenital valve defects
Do abnormal valves lead to insufficiency/leakage or stenosis?
Leakage
Large leaks of a valve lead to what changes?
-regurgitation back into the preceding heart chamber
-enlargement of proximal chamber and subsequent volume overload
Severe volume overload leads to what?
Heart failure
Where are the most common acquired valvular insufficiencies in the horse?
Aortic and mitral
Aortic and mitral insufficiency lead to what problems?
Left sided volume overload and pulmonary hypertension
True or false, horses usually do not develop pulmonary edema unless pulmonary hypertension occurs rapidly
True
In the horse, left sided overload and pulmonary hypertension usually lead to what?
Right sided failure
If atrial enlargement occurs (from regurg) the horse is predisposed to what arrhythmia?
atrial fib
What are the clinical signs of aortic/mitral insufficiency?
-exercise intolerance
-reduced performance
-mumurs
-tachycardia
-cough
What sign might be seen in the case of a rupture chordae tendonae?
pulmonary edema
What clinical signs might be seen in a case of tricuspid insufficiency?
-jugular distension w/ pulsdation
-subcu edema
-venous distension
-murmur over tricuspid valve
Color flow Doppler can give what information in the case of aortic or mitral insufficiency?
Degree of regurgitation
The prognosis for an aortic or mitral insufficiency is good with what conditions?
-asymptomatic
-regurg jet is small
-no evidence of left heart enlargement
What conditions make an aortic or mitral insufficiency a guarded or poor prognosis?
-exercise intolerance
-fractional shortening < 30%
-pulmonary artery larger than aorta
-evidence of endocarditis or myocarditis
-left atrial enlargement
True of False, the intensity of a murmur is NOT a reliable indicator of prognosis.
True
When would you treat a cardiac condition in a horse?
Only when signs of heart failure are present
What drug is used in a left sided heart failure?
Hydrazaline
What is the cause of endocarditis?
An acquired condition- focus of infection any where in the body that embolizes to the heart
Which organisms are the common causes of endocarditis?
-Pastuerella
-Actinobacillus
-Streptococcus
What condition may predispose a valve to bacterial colonization?
Pre-existing valve lesion
What are the possible clinical signs of endocarditis?
-may be sub clinical
-may cause heart failure
-tachycardia
-murmur of valvular insufficiency
-fever
-anorexia
-decreased performance
-younger animals (<4 years)
-shifting leg lameness
His is endocarditis diagnosed?
-visualization of abnormal valve of echo
-inflammatory leukogram
-hyperfibrinogenemia
-hyperglobulinemia
-blood culture (difficult)
-identif primary infection
How do you tx endocarditis?
-long term abx
-treat for heart failure if present
-treat primary focus of infection
What is the prognosis for endocarditis?
Good i tx before significant valvular lesions develop
If the valves have significant lesions, what is the prognosis?
Poor to grave - 80% of horse with aortic/mitral valve endocarditis die
Cardiac inflammation, degeneration or myocyte electrolyte changes from myocaridal dz can lead to what?
-altered conduction and arrhythmias
-reduced mycardial function, chamber dilation, insufficient AV valves and heart failure
-may lead to arrhythmias and murmurs
What type of murmurs are heard with myocardial dz?
systolic (AV valves)
Which arrhtyhmias are seen with myocardial dz?
-ventricular tachycardia
-premature atrial or ventricular contractions
-atrial fibrillation
Diagnosis of myocarditis can be difficult, but it is important to indentify what?
The underlying cause
What tx steps are taken for myocarditis?
-tx underlyin cause
-provide electrolyte support
-NSAIDs
-steroids if viral
-abx if bacterial
-tx symptomatic heart failure if present
-tx arrhythmias if present
-Mg, lidocaine if ventricular
-quinidine with atrial fib
-strict rest
What is the prognosis of myocarditis?
-good if caused by an electrolyte abnormality
-guarded if myocardial degeneration or inflammation
In general, pericarditis can be caused by what?
-septic
-non-septic
-neoplastic
-idiopathic
What bacteria are common causes of pericarditis?
Streptococcus
Gram negative bacteria +/- anaerobes
Horses with what other conditions may develop pericarditis?
Pleuropneumonia
EHV-1
How does pericarditis affect the heart?
Thickened and inflammed pericardium cause cardiac tamponade and restrictive pericarditis--interfers with diastolic filling, results in cardiac insufficiency
What are the clinical signs/physical findings of pericarditis?
-fever, depressionm anorexia
-pleurodynia
-colic
-cardiac tamponade
-jugular distension, edema
-pleural effusion
-muffled heart sounds
+/- plerual friction rubs
+/- arrhythmias
Which physical finding is the most specific for pericarditis?
Tamponade
What dx test is most specific for pericarditis?
Echo
What would you expect to see on an echo of pericarditis?
Pericardial fluid and collapsed right atrium
What other diagnostic steps can be taken?
-aspirate of pericardial fluid for cytology and culture
-electrical alternans on ECG
-Non-specific evidence of infection or inflammation (leukocytosis, hyperfibrinogenemia, hyperglobulinemia)
How can pericarditis be treated?
-pericaridal drainage and lavage
-abx tx
-anti-inflammatory and anlgesic tx
-tx arrhythmias and cardiac failure if present
Which heart rate is more common in horses with pathologic arrhythmias?
Tachyarrhythmia
Where does a supraventricular arrhythmia originate?
-SA node
-atrium
-AV node or junction
From where else can an arrhythmia originate?
Ventricle
Do large animals premature timing arrhythmia or escape timing (occurs later than expected)?
Premature arrhythmia
Arrhythmia frequency can be classified as what 3 types?
-isolated abnormal complexes
-paroxysmal
-sustained
What is the most common acquired pathologic arrhythmia in horses?
Atrial fibrillation (supraventricular)
What are the predisposing factors of atrial fibrillation?
-atrial enlargement
-valvular regurgitation
-heart failure
-myocarditis
-slow atrial rate and high parasympathetic tone
Is exercise intolerance a sign of atrial fibrillation?
Yes but only present in 60% of cases
What causes the clinical signs of atrial fibrillation?
Reduced filling of atria
What other clinical can be seen?
-dyspnea
-epistaxis
-colic
Only 12% of horses with atrial fib show signs of what condition?
heart failure
What type of rhythm is ausculted in atrial fib?
irregularly irregular w/o audible S4
-variable intensity heart sounds from beat to beat
-rate is usually normal
In cases of atrial fib, what is the most common murmur that might be heard?
Mitral regurgitation
What would you expect to see on an ECG of a horse with atrial fibrillation?
-absence of P waves
-irregularly irregular R-R interval
-normal ARS
-baseline F waves
What 2 drugs are given to convert the atrial fib?
-Quinidine
-Digoxon
Once the arrhythmia converts, which drug do you discontinue?
Quinidine- toxic signs may develop
What are the signs of quinidine toxicity?
-colic, diarrhea
-nasal mucosa edema leading to respiratory obstruction
-ataxia, behavior change, seizure
-tachycarida, other arrhythmias, prolongation of QRS
-hypotension and collapse
How do you tx quinidine toxicity?
-bicarb
-digoxin if tachycardia
-lidocaine if ventricular tachycardia
What is the prognosis for atrial fibrillation?
-good to excellent of iopathic A-fib with a normal heart and acute.recent onset
-good if chronic A fib and no sign of failure on echo
-guarded to grave with underlying heart dz
What is the cause of Atrial premature contractions (APC)?
Impulse originating in the atria but outside the SA node or from the AV junction
True or false...30% normal horses have 1 APC per minute.
False...1 per hour
When are APC's considered abnormal?
-if frequent
-occur in groups
-multi-focal in origin
APC may occur in horses with what other conditions?
-myocardial dz (esp following EHV1 or other respiratory dz)
-abnormal electrolytes
-toxemia or septicemia
-cardiac dz causing atrial enlargement
What is meant by atrial tachycardia?
More than 4 premature complexes in a row or a sustained atrial tachycardia
What would you expect to auscult on a horse with APCs?
-heart beat earlier than expected, followed by a normal diastolic interval
-if runs of APCs or atrial tachycardia- increased rate
An ECG of APCs will show what?
-premature P wave of different conformation than those that originate from SA node
-normal QRS
-P wave of APC may be buried in previous T wave
-if single, P-P interval normal following APC
-increased rate with atrial tachycardia
What is the treatment for APCs?
-corticosteroids if suspicious of viral myocarditis
-Atrial tachycardia (>100 bpm) requires quinidine, digoxin (if heart failure)
What are ventricular premature contractions?
VPCs are ectopic beats originating from a ventricular focus and occur earlier than expected
What defines ventricular tachncardia?
4 or more VPCs in a row or sustained
What are the causes of VPCs?
-electrolyte abnormality
-myocarditis
Are occasional VOCs and ventricular tachycardia normal or abnormal?
Abnormal
What do you expect to hear on auscultation of VPCs?
-regular rhythm with a beat occuring earlier than normal, followed by a compensatory pause
Clinical signs of underlying myocarditis or electrolyte disturbances are most common with what disease in horse?
Endotoxemia= GI disease
Sustained ventricular tachycardia is most likely to be associated with what condition?
Heart failure
1) What does a Viruses lack.
Viruses do not have:
1. a nucleus
2. organelles
3. ribosomes
4. cytoplasm
5. only a few have enzymes
How would you treat an occasional VOC with a normal rate?
Stall rest
At what heartrate do you consider ventricular tachycardia to be associated with disease?
> 60 bpm
What are the indications of a dangerous ventricular tachycardia that needs immediate attention?
HR > 120 bpm
R on T configuration
Multifocal origin of QRS
How is ventricular tachycardia treated?
-mag sulfate IV
-lidocaine
-quinidine
-treat underlying dz
Bradycardia may accompany what conditions?
-myocardial dz
-cerebral dz
What is the heary rate seen with bradycardia?
< 24 bpm
What changes do you see on an ECG of a horse with bradycardia?
Normal complexes, slow rate
How do you treat bradycardia?
Treat underlying cause
What is third degree AV block?
Acquired abnormality of the junctional myocardium that does not allow impulses from the atria to conduct to the ventricles
What is the order of depolarization of the atria and ventricles wtih 3rd degree block?
Atria and ventricle depolarize separately under control of their own pacemakers
Third degree AV block is more commonly associated with what condtions?
-myocarditis
-degenerative changes in the AV node or electrolyte changes
What are the clinical signs/ physical findings of 3rd degree Av block?
-exercise intolerance and collapse
-occasional signs of heart failure
-slow heart rate <24 bpm, typically regular rhythm
What would you see on an ECG of a 3rd degree AV block?
-no relationship between P and QRS
-QRS look slightly abnormal
What is the tx for 3rd degree AV block if caused by non-septic myocarditis
Corticosteroids
What other steps are taken for tx fo 3rd degree AV block?
-check electrolytes
-stall rest
-resolution requires implantation of a pacemaker
What are the common causes of acute blood loss?
-trauma
-guttural pouch mycosis
-hemoabdomen
-hemothorax
What are the clinical signs of hypovolemia?
-tachycardia
-decreased pulse pressure
-reduced jugular fill
-tachypnea
-cold extremities
-decreased urine output
-depressed mentation
How do you tell evidence of regeneration in an anemic horse?
-no reticulocytes so look for MCV (bigger RBCs)
Does a horse with acute blood loss show hyper or hypoproteinemia?
Hypoproteinemia
What value is U/S in diagnosing acute blood loss?
-visualization of an active bleed
-fluid within the abdomen/thoracic compartments
Class 1 category of blood loss is a loss of hoe much of the blood volume?
15% or less
Class 1 blood loss is fully compensated by what mechanism?
Transcapillary refill--pulls from the interstitium
How much is 15% of the blood volume in a 500 kg horse?
6 liters
What clinical signs are seen with 15% blood loss?
Few clinical signs are observed
Category 2 blood loss is a loss of how much volume?
15-30% total blood volume
What is orthostatic hypotension?
Blood pressure falls when the horse stands, causing dizziness
Class 2 blood loss shows increased HR and what kind of MAP?
Normal
What other effects are seen in class 2?
-decreased urine output
-compromised splanchnic perfusion
(bacterial and endotoxin translocation, sepsis, sever sepsis, septic shock, MODS, death)
Class 3 of blood volume loss is 30-40% of total blood volume, what happens to compensatory mechanisms?
-vasoconstrictor response to hemorrhage is no longer able to sustain perfusion of vital organs
-homeostatic mechanisms fail
-decompensated hypovolemic shock
Why is hypotension exaggerated in class 3?
-loss of vasoconstriction
-increased adenosine due to loss of ATP production (adenosine=vasodilator)
What occurs in class 4 blood loss?
> 40% volume loss
-irreevsible decompensation
In compensatory shock, all is well if what parameter is maintained?>
MAP
What is the goal of the homeostatic response?
Move interstitial volume into vascular space
-support blood volume/pressure
-provide O2
Which organs get perfused first in compensatory shock?
-brain
-heart
-lung
-kidney
At what point does the RAAS system initiate?
Decreased perfusion of renal arteriole
What 2 other homeostatic mechanisms help to increase volume?
-Arginine vasopressin (ADH)
-sympathetic nervous system activation
What are the clinical signs of early decompensated shock?
-altered mentation
-prolonged CRT
-tachycardia
-hypotension
-oliguria
What are the signs of late decompensated shock?
-prolonged tissue hypoxia
-autoregulatory failure (vasodilation, pupils fixed and dilated, hypothermia, sever acidosis)
In hypovolemia, mortality and morbidity are related to what?
volume and duration of blood loss
What factor is the enemy of the bleeding patient?
Time
What steps should be taken as the first line of defense/treatment in the case of traumatic blood loss?
-rapid intervention to prevent further loss: ligation of arterial vessels, application of pressure bandages
In the case of traumatic blood loss, the 2nd step is initiating fluid tx, what fluid should you use?
-crystalloids at shock dose (hypertonic saline)
-40-80 ml/kg (give 10 L to start and evaluate)
When should blood products be given?
In the case of sever loss
What are the indications for whole blood transfusion?
PCV < 20% acutely
PCV < 12% for 12-24 hours following blood loss
True or False, PCV is the sole transfusion trigger?
False- should also include blood gas information (SaO2 should be 95-100%)
How much whole blood can you transfuse?
20-40%, then marrow replacement should be started
How do you calculate the amount of blood needed for a transfusion?
PCV desired - PCVpatient x .08 Bwt
______________________________
PCV donor
How much blood can a horse safely donate?
25% of blood volume
What are the causes of hemoabdomen?
-trauma
-post-op sx hemorrhage
-neoplasia
-complications from foaling and preg
-visceral organ rupture
-mesenteric injury
-coagulopathy
-ovarian hematoma
-systemic amyloidosis
-idiopathic
What are the clinical signs of hemoabdomen?
-colic
-lethargy
-hypovolemic shock
-anorexia
-reluctance to move
-weakness/trembling
-abdominal distension
Hemoabdomen is a mature horse dz seen more in which breeds?
-arabs
-TB
How is hemoabdomen diagnosed?
-anemia
-increased lactate
-decreased CVP
-abd U/S
-peritoneal fluid
What is are the primary goal when treating hemoabdomen?
-control hemorrhage
-control hypotension
(MAP > 60, maintenance fluids only)
Why isn't hypertonic saline given in a case of hemoabdomen?
Would increase blood pressure too much
What steps are taken to tx hemoabdomen?
-tranquilizer (ACE)
-quiet environment
-no forced movements
-blood transfusion when life threatening anemia
-O2 if not stressful
-anti-fibrinolytics
-pro-coagulants
What is the survival rate of hemoabdomen?
51-74%, 84% for periparutient hemorrhage in mares
The short term outcome of hemoabdomen is related to what?
The underlying cause
-ability to control hemorrhage
-restore effective circulating volume
What are the causes of hemothorax?
-trauma
-neoplasia
-coagulopathy
-iatrogenic
What is vasculitis?
Clinicopathologc process that involves inflammation and necrosis of blood vessel walls
Is vasculitis usually a primary dz?
No, typically and 2ndary manifestation of a primary infectious, toxic or neoplastic disorder
What is the hallmark sign of vasculitis?
Predominant involvement of small vessels in skin
What are the clinical signs of vasculitis?
Primary distal limb edema
-hyperemia
-P/E hemorrhage
-ulceration of mucus membranes
Limb edema may lead to what other complications?
skin infarction, necrosis, exudation
Are hemorrhage and vascular necrosis from vasculitis limited only to the limbs?
No, can affect any organ system (lameness, colic, dyspnea, ataxia)

sequelae: cellulitis, thrombophlebitis, laminitis, pneumonia
What are the 4 main causes of vasculitis?
-equine purpura hemorrhagica
-equine viral arteritis
-equine infections anemia
-idiopathic
Is equine purpura hemorrhagica a contagious dz?
No
EPH is a squealae to what other diseases?
-systemic dz
-strep equi (esp following vaccination for strangles)
-strep zooepidemicus
-rhodococcus equi
-corynebacterium pseudotuberculosis
What are the signs of EPH?
-young to middle age horses
-signs develop 2-4 weeks following respiratory infection
-vasculitis syndrome: subcu edema distal limbs, lethargy, anorexia, P/E hemorrhage, fever
What lab results would you expect to see with EPH?
-anemia
-neutrophilia
-hyperproteinemia
-hyperfibrinogenemia
-elevated muscle enzymes
-TCP (rare)
What will a skin bx show in a case of EPH?
Classic, leukocytoclastic vasculitis with necrosis of blood vessels
-immune complexes of IgM/IgA
-strep M proteins
What is the TX for EPH?
-tx underlying dz
-PCN (hx of strep)
-hydrotherapy
-distal limb bandages
-steroids (prolonged course 2-4 week min)
-continue abx
The prognosis for recovery form EPH depends on what?
-early recognition
-early aggressive therapy
-extent of organ involvement
What are the potential complications from prolonged recovery from EPH?
-laminits
-cellulitis
-pneumonia
-diarrhea
The virus that causes Equine Viral Arteritis is in which family?
Arteriviridae
RNA virus, enveloped
Which arthropod carries EVA?
None-it's a non-arthropod borne virus
Is EVA an infectious dz?
Yes
How soon do clinical signs develop after infection with EVA?
1- 10 days following inmfection
What are the clinical signs of EVA/
-fever
-lethargy
-anorexia
-vasculitis/edema (of mammary gland, scrotum, limbs, periorbital, ventral edema)
-stiffness
-rhinorrhea
-abortion (10-60% between 3-10 months gestation)
Do mares become chronic carriers of EVA?
No
What lab results do you expect in the dx of EVA?
Results are variable and not diagnostic for EVA
What is the target organ for the EVA virus?
Blood vessels- localizes in the endothelium
What is the histologic appearance of the vasculitis caused by EVA?
-fibrinoid necrosis or tunica media with perivascular lymphocytic/granulocytic infiltration, thrombi are present
How is EVA transmitted?
Aerosolized particles from infected horses
-respiratory secretions
-urinary tract secretions/urine
-abortive tissues
Semen
How quickly can mares eliminate the virus?
60 days
Stallions can be life-long carriers, and show what clinical signs?
None
How is EVA diagnosed?
-4 fold increase in Ab titer
-serum positive stallions require semen testing
What type of virus cause Equine Infectious Anemia?
Retroviradae, Lentivirus
Rna, reverse transcriptase
How is EIA transmitted?
-by blood, from Tabanid insects (horsefly, deerfly)
-fomites
-vertical transmission
What are the 3 stages the EIA can occur as?
-acute
-chronic
-inapparent
What are the signs of the acute stage?
-burst of viremia
-fever
-TCP
-malaise
-P/E hemorrhages
What characterizes the chronic stage of EIA?
-anemia
-recurrent episodes of viremia
-horses are sick ("swampers")
-episodes decrease in duration/severity
Any horse experienceing clinical EIA may also develops signs of what conditions?
DIC (may die)
What situations can induce recrudesence of EIA?
-stress from
-transport
-racing
-extreme temps

Steroids
Which test is used for EIA?
Coggins

also Elisa for screening
EIA is a reportable dz in the US and there is no vaccination, what is the size of the quarantine area for infected horses?
200 yards (180m)
Ingestion of what can cause Heinz Body Hemolytic Anemia?
-red maple leaf
-onions
-brassica
-phenothiazines
Red maple leaf toxicosis can occur in which species?
-horse
-pony
-zebra
-alpaca
When does red maple leaf toxicity tend to occur?
Late summer - fall
How soon do signs of toxicity develop and what causes the anemia?
2-3 after ingestion (1.5 - 3 pounds of leaves)

Gallic acid denatures Hbg
Ingestion of the wilted leaves leaves to what lab values?
-hemoglobinemia
-hemglobinuria
-methemoglobinemia

(denatured Hbg unable to carry or transport O2)
What are the clinical signs of Heinz body hemolytic anemia?
-anemia (tachycardia/tachypnea)
-chocolate colored mucus membranes
-brown/red urine
-ARF
-colic
Why would heinz body anemia cause ARF?
Pigment nephropathy- Hbg filtered at the kidney
On clinpath results, what is seen with heinz body anemia?
-acute,severe anemia (heinz bodies, eccentrocytes)
-azotemia
-hemoglobinemia
-pigmenturia
-increased methemoglobin
What is the tx regimen for heinz body anemia?
-IV fluids
-address colic pain as necessary
-whole blood transfusion often indicated

NO steroids! (associated with non-survival)
What is one of the most common neoplasms in horses?
Lymphoma
Does equine lymphoma have a viral etiology like bovine lymphoma?
No
What characterizes multicentric/generalized lymphoma in the horse?
-end-stage dz
-leukemia
The alimentary form of lymphoma occurs in what age and breed of horse?
< 5 years of age
-Arabians
Which form of lymphoma is the most common?
Splenic
Which form of lymphoma is primary for metastatic dz?
Thoracic (mediastinal/thymic)
Which type of cutaneous lymphoma has a poor prognosis?
Deeper tissue involvement
What are the clinical signs of lymphoma?
-lymphadenoapthy
-lethargy
-weight loss
-edema
-pyrexia
What changes in lab values would you expect with lymphoma?
-anemia (suppression of erythropoiesis, bone marrow infiltration, blood loss, immune-mediated
-lymphocyte count typically normal
-hyperglobulinemia/hypoalbuminemia
What is the tx for equine lymphoma?
Limted- complications are considerable
What is the function of mitochondria?
Use oxygen to provide energy to the muscles
What is the VO2 max of a horse compared to a human?
Human: 50 ml/kg/min

Horse: 140 ml/kg/min
Air is comprised of what percentage of oxygen?
21%
Horses are what type of breathers?
Obligate nasal breathers
How many pairs of sinuses does the horse have?
6 pairs
Which paranasal sinuses are most often diseased?
Frontal
Maxillary
What is the most common cause of primary sinusitis in the horse?
Streptococcus spp

may occur following a respiratory tract infection
What is the most common cause of secondary sinusitis?
Tooth root infection (tooth roots of molars within maxillary sinus)
What are the other causes of sinusitis?
-sinus cyst
-tumors
-facial bone fractures
What are the clinical signs of sinusitis?
-unilateral or bilateral nasal dischargs (can be foul smelling)
-ocular discharge
-malaise
-facial deformity if chronic
How do you diagnose sinusitis?
-PE, palpation and percussion of face
-endoscopic exam
-oral exma
-skull rads
-sinoscopy
-CT
-MRI
How do you tx sinusitis?
Like an abscess
-tx inciting cause
-abx
-repeated lavage with balanced polyionic solution
What is an ethmoid hematoma?
Benign, progressively expansive soft tissue mass
In what age of horse do ethmoid hematomas occur?
Middle age, 8-10 years

usually unilateral
What are the clinical signs of an ethmoid hematoma?
-uni or bilateral epistaxis
-respiratory stridor
-facial deformity
-decreased airflow through affected nostril
What other upper airway conditions can cause epistaxis?
-trauma
-neoplasia
-coagulopathy
What lower airway conditions can cause epistaxis?
Pulmonary hemorrhage
-neoplasia
-pulmonary infarction
-atrial fib and pulmonary hypertension
In addition to a PE, what other diagnostics are used for ethmoid hematomas?
-endoscopy
-biopsy
-rads
-CT
What is the appearance of an ethmoid hematoma on a histo slide from a bx?
angioma, cappilary, fibrous tissue
What are the tx options for an ethmoid hematoma?
-sx removal, sharp or laser
-formaldehyde injections (intralesional)
Lymphoid hyperplasia syndrome can occur in what areas of the nasopharynx?
-dorsal and lateral walls
-soft palate
-epiglottis
-guttural pouch lining
Grare 3-4 lymphoid hyperplasia is seen in which age of horse?
Younger, 2-3 y/o
What are the causes of pharyngeal lymphoid hyperplasia?
Infection
-bacterial
-viral

Environmental contaminants
-endotoxin
-ammonia
-dust
-metals
How is lymphoid hyperplasia distinguished from pharyngitis?
Lymphoid hyperplasia:
-young horse
-not systemically ill
-afebrile
-normal appetite
-BAR
What is the response of the lymphoid tissue to antigens?
-mucus production
-immunoglobulin secretion
What is the key component of respiratory dz?
Inflammation
What occurs in the condition of dorsal displacement of the soft palate?
Soft palate displaces dorsally to the epiglottis
How is DDSP diagnosed?
-exercise intolerance
-abnormal respiratory sounds during exhalation
-resting endoscopy (insensitive unless ulcer)
-treadmill endoscopy (better but not perfect?
What is the cause of DDSP?
Not known, possible neuromuscular dysfunction
What are the non-surgical tx for DDSP?
-rest
-tongue tie
-steroids
-Cornell collar
What is the best sx tx for DDSP?
Tie forward
-thyrohyoideus prosthesis (suture) moves larynx rostral and dorsal
What effect does thermopalatoplasty with a laser have?
Stiffens the palate
Dysphagia in foals can be a result of what conditions?
-cleft palate
-vit E/selenium deficiency
-neonatal nasopharyngeal dysfunction
-over zelous lactator
What are the clinical signs of nasopharyngeal dysfunction in foals?
During first month of life:
-respiratory distress
-respiratory stridor
-dysphagia/aspiration pneumonia
What might be seen during an endoscopic exam for nasopharyngeal dysfunction in a foal?
-nasopharyngeal edema
-laryngeal edema
-persistent DDSP
-mild in trahea
What are the clinical signs of cleft palate?
-milk dripping from nose/mouth
-coughing
-aspiration
How do you dx cleft palate?
-endoscopic exam
-palpation/examination of soft palate
What are the causes of cleft palate?
-genetics
-teratogens
-nutrition
-trauma
(uncommon congenital defect if foals)
What is the sx approach to tx cleft palate?
Mandibular symphisiotomy
When does a dynamic laryngeal obstruction become apparent?
-at exercise
-induced by nasal occlusion
What is the cause of idiopathic laryngeal hemiplasia?
Distal axonopathy of the left recurrent laryngeal nerve
What muscles does ILH affect?
Intrinsic laryngeal muscles, adductors, abductors NOT cricothyroid muscles
Which horse are at risk for ILH?
-large horse, > 18 hands
-TB 8%
-Draft 35%
What are the clinical signs of ILH?
-exercise intolerance
-respiratory noise
-coughing (eating)
How does ILH cause poor performance?
-incr inspiratory resistance
-decr minute volume
-decr PaO2, incr PaCO2
-decr VO2
-alteration in Fs:Fr coupling
-increased work of breathing
During exercise, a grade 3 ILH collapse how much?
70%
How do you Dx ILH?
History of:
-exercise intolerance
-respiratory noise

Endoscopic exam:
-resting
-treadmill
Overall, what is the goal of Tx for ILH?
Increase the diameter of the airway
what is the function of IL-5? (2)
1. B cell proliferation
2. Helps B cells switch to IgE production
What other procedures are recommended for ILH?
-maximize size of rima glottidis
-laryngoplasty + ventriculocordectomy or ventriculectomy or cordectomy
-best airway function
-resolution of noise?
-avoid complication of vocal fold collapse
What are the potential complications of Tx ILH?
-coughing
-aspiration
-continued exercise intolerance
-noise
What is arytenoid chondritis?
Inflammation of the cartilage with abscess
What tissues can trap the epiglottis?
Aryepiglottic tissue, when inflammed
What is the tx for epiglottic entrapment?
Transection of the aryepiglottic membrane
-anti-inflammatories or nothing
What is guttural pouch tympany?
-excessive accumulation of air and sometimes fluid in the guttural pouch

(foal < 1 year old)
What are the clinical signs of guttural pouch tympany?
-swelling in parotid region
-dyspnea
-dysphagia
-aspiration penumonia
How is GP tympany dx?
-rads
-endoscope
How is GP tympany treated?
2 sx options
-guttural pouch fenestration
-modify the nasopharyngeal opening (resection of salpingo membrane)
What is guttural pouch empyema?
Suppurative inflammation of the guttural pouch
When does guttural pouch empyema occur?
Following upper airway infection involving Strep
What are the clinical signs of guttural pouch empyema?
-mucopurulent nasal discharge
-swelling in parotid region
-dsypnea
-dysphagia (mass effect, neurogenic)
How doe you Dx guttural pouch empyema?
-rads
-U/S
-endoscopic examination
-culture and sensitivity
What is the Tx for guttural pouch empyema?
-irrigate the guttural pouch with balanced electrolyte solution
-systemic abx (PCN)
-drain guttural pouch via Viborg's triangle or modified Whitehouse
What type of med should never be used in the guttural pouch?
No caustics i.e. iodine
Guttural pouch mycosis is a result of what type of infection?
Aspergillus spp
What is the primary clinical sign of Guttural pouch mycosis?
Epistaxis
Other clinical signs of Guttural pouch mycosis include what?
-horner's
-dysphagia
What would you expect to see on an endoscopic exam of Guttural pouch mycosis?
-blood from the guttural pouch opening
-blood within the pouch
-fungal plaques
What is the tx for Guttural pouch mycosis?
-occlude the affected arteries
(internal carotid is most commonly affected)
Bleeding from the guttural pouch and what in the history would lead you to suspect an avulsion of the rectus and longus capitus muscles?
Hx of trauma
What causes temporohyoid osteoarthopathy?
Following otitis media/interna or some inflammatory episode, the stylohyoid bone fuses with the petrous temporal bone
What is the sequlae of temporohyoid osteoarthopathy?
Can impinge on Cn 7 and 8 or the bone fractures- vestibular dz and facial nerve paralysis results.
What are the clinical signs of temporohyoid osteoarthopathy??
-acute onset of vestibular dz
-facial nerve paralysis
-head shaking
-pain associated with palpation of ear
What are the signs of CN VII damage?
CN VIII?
CN VII: drooped muzzle, ear

CN VIII: vestibular signs
What are the txs for temporohyoid osteoarthopathy?
-sulfa abx
-nsaids
sx:
-stylohyoid osteotomy
-ceratohyoid osteotomy
-tarsorhaphy (sx closure of eye)
In terms of lung dz, what is a bleeder horse?
Exercise induced pulmonary hemorrhage
What characterizes EIPH?
-evident following intense exercise
-characterized by blood in the airways
-associated with poor racing performance
What is the potential etiology of EIPH?
Pulmonary capillary disruption
-high pulmonary artery pressure
-very negative inspiratory pressure
Which horse breeds are affected by EIPH?
-all TB racehorses
-most SB racehorses
-62% racing quarter horses

Western pleasure horse- safe, slower speed
What are the clinical signs of EIPH?
-5% will have epistaxis
-blood in the trachea 45-60 mins post exercise
-hx of poor performance
On post mortem of EIPH, where is bleeding seen?
Caudal dorsal lung fields
What is the Tx for EIPH?
There is none, can give furosemide to decrease pumonary arterial pressure
What can be done for EIPH?
Reduce components of transmural pressure
-insp. driving pressure
-pulmonary capillary pressure

Inspiratory obstructions
-ILH
Inflammation of the respiratory system can have what effects?
-constriction
-mucus, edema
-tissue damage
-remodeling,fibrosis
What are the clinical signs/findings of inflammatory airway dz?
-mucus
-inflammatory cells
-/+ cough
-no fever
-normal appetite
-not sick
What percentage of racehorses have inflammatory airway dz?
33%
What are the infectious causes of inflammatory airway dz?
Viral:
-influenza
-herpes virus
-rhinovirus

Bacteria
-strep
What are the non-infections causes of inflammatory airway dz?
-allergy
-particulates
-endotoxin
What are the major contributors to particulates that can cause inflammatory airway dz?
-bedding
-hay
-barn activites
Which horses are more at risk for inflammatory airway dz?
Younger <4
-recently entered race training
-feeding hay vs pasture
What is the importance of the affect of inflammatory airway dz?
Amount of mucus can affect the way a horse finishes a race.
What is the tx for inflammatory airway dz?
-Anti inflammatories ( be careful w. abx), steroids
-abx
-improve the enivronment
What is another name for reactive airway obtsruction?
Heaves
How is heaves characterized?
-Inflammatory condition of the lower airway characterized by the presence of bronchospasm, mucus plugs and chronic changes to the bronchiolar walls leading to terminal airway obstruction
heaves is thought to caused by what?
Allergy to inhaled antigens such as dust from feed and beeding
What are the clinical signs of heaves?
-older horse
-coughing
-exercise intolerance
-increased respiratory rate and effort
-flared nostrils
-double expiratory effort
What will you hear when ausculting the chest on a horse with heaves?
-crackles
-wheezes
In dx heaves, the horse is typically > 10 yrs of age with a cough that is worse, when?
In the barn
What would you expect to find on PE?
-no fever
-good appetite
-abnormal tracheal and pulmonary auscultation
How is heaves dx?
-rads
-BAL (>15% neutrophils)
-endoscopy
-atropine test
-ABG
Thoracic auscultation may be normal during normal tidal breathing, what method can you use to increase the respiratory rate?
Re-breathing bag
What are the goals of tx for heaves?
-prevent exposure to offending antigens
-decrease pulmonary inflammation
-supportive care

(no nsaids- leukotriene pathway)

Give steroids
What is the most effective tx for heaves?
Environmental change- turn your horse out
What additional steps can be take for heaves?
-feed pellets, bed on shavings
-soak hay or feed hay cubes
-steroids
-bronchodilators
What is the genus/species for the equine lungworm?
Dictyocaulus arnfieldi
What is the role of the donkey in the infection of the horse with lungworm?
Donkey is the asymptomatic source
In the horse, the lungworm life cycle is arrested in which stage?
Adult stage, burrows into lungs
What clinical signs are seen the horse with lungworm?
-parsitic bronchitis
-copius mucus production
-cough
-crackles, wheezes caudal and dorsal
-2ndary bacterial infection
-pulmonary edema
-coughin
-increased respiratory effort
How is lungworm dx and tx?
-history of contact with donleys or mules
-eosinophils and larvae on tracheal aspirate or tracheal wash
What are the 2 most common causes of viral respiratory dz in the horse?
-influenza A
-herpes 1,4 virus
Equine influenza A is what type of virus?
-SS RNA, orthomyxoviridae
Equine influenza A virus has tropism for which cells?
Epithelium of the respiratory tract
-ciliated epithelium of the trachea and bronchi
-impairs the mucociliary clearance
What are the clinical signs of Equine influenza A? (#1 cause of URTD)
-highly contagious (1-5 days)
-serous nasal discharge
-cough
-fever
-inappetence
-muscle soreness
-lymphadenopathy
How is Equine influenza A dx?
-nasopharyngeal swab
(virus isolation, elisa, pcr)
-serology
What is the tx for Equine influenza A?
-supportive care (access to food/water)
-rest (no training)
-anti-pyretic meds (banamine)
What is the in vaccinating against Equine influenza A?
Decreases the severity of infections, does not prevent it
Which horses are at risk for Equine influenza A?
-naive horses
-neonates
-geriatric, immunosuppressed

2ndary complications:
-pneumonia
-bacterial infection of upper airway
-viral cardiomyopathy/myocarditis
What type of virus is equine herpes virus 1 and 4?
-DS DNA, herpesviridae
What effects does herpes 1,4 have on the respiratory tract?
-local lymph nodes infection
-leukocyte associated viremia
-disseminates to distant organs including gravid uterus and CNS
What effect does herpes 1,4 have on vascular enodthelium?
Viral replication causing vascultitis, hemorrhage, thrombosis, necrosis
Where does the latent herpes 1,4 virus hide?
In the trigeminal ganglion and leukocytes of the lymphoreticular system
What are the clinical signs of upper respiratory tract infection of herpes 1,4?
-serous or purulent nasal discharge
-ocular discharge
-fever, malaise
-limb edema
What other major complications can arise from herpes 1,4?
-abortion, last trimester
-myeloencephalopathy
-pulmonary vasculotropic infection
How are respiratory viruses spread?
Fomites
What is the TX for EHV 1,4?
-supportive care
-analgesia, anti pyrexic
--access to food/water
-warmth
-acyclovir (EHV1)
-no exercise
Can EHV be prevented/
vaccine offers some protection against respiratory signs and abortion, but not encephalopathic dz
What causes the development of bacterial pleuropneumonia?
-bacteria colonize the lung resulting in pneumonia, abscessation and inflammation of the pleura with accumulation of pleural fluid
What are the risk factors for developing bacterial pleuropneumonia?
-viral infection
-transport with head tied up
-post anesthesia or stress
Dx of bacterial pleuropneumonia should include what components?
-Hx and pE
-thoracic auscultation
-thoracic rads
-thoracic U/S
-thoracocentesis
-tracheal wash
-CBC/fibrinogen
What finding would you expect on PE of a horse with bacterial pleuropneumonia?
-depressed/lethargic/inappetent
-fever
-tachycardia
-tachypnea/cough
-pleurodynia
-auscultation: crackles, wheezes, pleural friction rubs
-cyanosis
What are the DDX's for bacterial pleuropneumonia?
-fungal pneumonia
-granulomatous lung dz
-EHV 5
-neoplasia
What is the Tx for bacterial pleuropneumonia?
-Abx
-thoracic drainage
-IV fluids
-plasma
-nsaids
-O2
What Abxs should you consider in tx bacterial pleuropneumonia?
Mitronidazol (for anaerobes) and PCN
Which analgesics are considered for tx of bacterial pleuropneumonia?
-Nsaids
-lidocaine infusion (somatic)
-intercostal anesthesia
-ketamine infusion
When would colloids be given to a horse with bacterial pleuropneumonia?
-with hypoproteinemia
-vasculitis
-inflammation
What additional complications can arise from bacterial pleuropneumonia?
-laminitis
-thrombophlebitis
-enterocolitis
-chronic abscessation
-bronchopleural fistula
What are the clinical signs of thoracic trauma?
-shallow, fast breathing
-ventral increase in lung sounds
-dorsal decrease in sound or nothing heard