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82 Cards in this Set
- Front
- Back
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What does the Vd of drug tell you?
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large Vd= the drug is distributed throughtout a variety of tissues and extracellular fluids (does not necessarily mean high intracellular concentration or good membrane penetration)
small Vd= the drug remains primarily in the vasculature |
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penicillins spectrum, mode of action, Vd, safety
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penicillin Na or K, procaine G: strep, most clostridium
ampicillin, amoxycillin: some gram negative, strep, staph methicillin:strep, staph ticarillin: P.aeroginosa, strep, expensive so foals or regional therapy only mode of action: inhibits cell wall synthesis, time dependent killing small Vd poorly lipid soluble renal excreation wide margin of safety, but is assoicated with anaphylactic shock |
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cephalosporins:
spectrum Vd safety |
3rd generation
Na ceftiofur (ceftazidime) resistant to many beta lactamases: strep, staph, some gram negative at larger doses, P. aeruginosa only parenteral administration half life 2 hrs Vd: tissue distribution is good, however: poor membrane crossing! renal excretion side effects: immune mediated dermatitis Cl. difficile associated diarrhea |
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aminoglycosides:
spectrum mode of action Vd safety |
gentamicin, amikacin(foals only) neomycin, kanamycin, tobramycin,: gram neg. some staph
inhibits bacterial protein synthesis, cidial concentration dependent killing parenteral or topical synergism with beta lactams small vd half life 2 hrs, poor membrane cross-over, deactivation in necrotic material or acidic environment renal excretion and nephrotoxic-time dependent uptake by proximal tubular cells, so dose once daily |
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Fluorquinolones:
spectrum Vd mode of action safety |
enrofloxacin
marbofloxacin, ciprofloxacin spectrum:gram neg. some staph no anerobes gyrase inhibitor concentration dependent killing parenteral or enteral large Vd, very good tissue penetration due to lipophilia does not reach CNS excreted through bile, kidney, intestine toxic in cartilage of young growing animals (less than 5 years) synergism: beta lactams, metronidazole |
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Macrolides:
spectrum Vd safety |
erythromycin, azithromycin, clarithromycin, lincomycin, clindamycin, spiramycin, tylosin
gram postive and intracellular pathogens use in combo with rampfin in rhodococcus equi infected foals or lansonia intercelluarsis large Vd in most fluids and tissues DO not use in adults- life threatening typhlo-colitis safe in foals under six months static, but can be cidal in large doses |
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tetracyclines:
spectrum Vd safety |
oxytetracycline
doxycycline (tetracycline) topical time dependent killing static broad spectrum: rickettsiae(anaplasma, borrelia, ehrlichia risticii aka neorickettsia risticii) good for long term treatment of strep equi abscess reasonbaleVd reasonable CNS penetration renal excretion although enerohpeaticcirculation prolonges half life toxcity: typhlo-colitis in adult horses although rare liver damage when renal excretion is impaired do not give if discolored! binds O2 and get nephrotoxcitiy |
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chloramphenicol:
spectrum Vd safety |
chloramphenicol (florfenicol)
broad spectrum (anaerobic and rickettsia) static time dependent large Vd lipophilic good CNS penetration enteral and parenteral administration do not give to animals that will be used for humane consumtion causes aplastic anemia |
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potentiated sulfonamides
spectrum Vd safety |
trimethoprim sulpha
broad spectrum, no anaerobes time dependent killing cidal enteral parenteral PABA folate metabolism some resistance reasonalbe tissue penetration CNS penetration cheap antibiotic-induced colitis in adult horses immune-mediated disorders? |
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Rifampin
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rhodococcus tx in foals
high intracelluar concentrations only given in combo with macrolide |
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metronidazole
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clostridium difficile, (bacteroides spp)
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How to treat?
Horse with a choke that was just flushed out increased res rate and effort, and increased respiratory sounds with crackles and wheezes predominantly ventrally t and R more than L |
Parenteral by preference
AB gentamicin and pen or ceftiofur or TMS NSAIDS: phenylbutazone or flunixin meglumine bronchodilator: clenbuterol |
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How to treat?
horse with pleuropneumonia fever, reluctance to walk, horizontal percussion line with dorsally increased sounds with crackles and wheezes venterally silence totale |
parenteral by preference
chest drainage AB: gentamicin, pen, metronidazole or enrofloxacin, pen, meetronidazole or chloramphenicol, preferably at later stage NSAIDS: flunixin meglumine Broncodilator: clenbuterol |
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strongyles dewormers
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moxidectin (do not give to foals less than 4mon)
ivermectin pyrantel benzimidazoles large killed at any stage with IVM or MXD only late L3 are killed by MXD in small early L3 are killed by fenbendazole |
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strongyloides westeri dewormers
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ivermectin
pyrantel benzimidazoles! |
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parascaris dewormers
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pyrantel
ivermectin benzimidazoles moxidectin (not less than 4m) careful in weaned hores that have never been wormed before, common for obstruction |
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tapeworms dewormers
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praziquantel, pyrantel (2-3x)
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bots treatment
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ivermectin
moxidectin |
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NSAID properties
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anti inflammatory
analgesic anti-endotoxic anti-pyretic anti-thromotic side effects gastro-intestinal hemorrhage and nephropathy |
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aspirin use
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only to decrease platelet aggregation cox-1 inhibitor
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the one and only dose for phenylbutazon
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2.2mg/kg every 12 hr
(1g Q12hr in a 450kg(1000lb) horse |
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NSAID toxicity
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decreased renal blood flow
decreased mucosal blood flow with right dorsal colon most intensely affected -ulceration -protein loss -endotoxemia -laminitis |
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common causes of colic in young horses(less than3yr)
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intussusception;ascarid impactions; gastric ulcers;foreign body obstruction/fecoliths
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common causes of colic in middle age horses (7-10yr)
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cecal impaction;epiploic formen entrapment; enterolithiasis
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common causes of colic in old horses(greater than 10yr)
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enterolithiasis; pedunculated lipoma; other neoplasia; fecoliths
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common causes of colic in american miniatures
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fecoliths and enteroliths
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common causes of colic in STBD's and belgians
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inguinal hernias
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common causes of colic in arabians and morgans
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enteroliths
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common causes of colic in stallions
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inguinal hernias
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common causes of colic in mares
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large colon volvulus and uterine torsion granulosa cell tumor
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alfalfa hay causes what type of colic
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enteroliths
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bermuda grass hay common feed in what type of colic
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ileal impactions
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abdominal distention in adult verus foal
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adult-most likely cecum or large colon
foal-SI, cecum, large colon |
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colic conditions causesing increased temperature
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sand colic (normal to 102.5)
enteritis endotoxemia- rupture infectious- abscess, viral, ect |
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common causes of decreased temperature
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artifactual from pneumorectum;
shock |
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transrectal palpation palpable structures
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pelvic flexure
parts of ventral and dorsal colon cecum w/ventral band and rarely duodenum mesenteric root in smaller horses lliac arteries and desecending aorta small colon spleen left kidney nephrosplenic space bladder SI not palpable unless distended or thickened uterus ovaries internal inguinal ring |
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capacity of stomach
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8-15L
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abdominocentesis
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first change observed is an increase in fluid volume
normal:TP less than 2; WBC less than 5000 L.I. surgical obstruction TP greater than 2 WBC variable S.I. strangulating obstruction TP greater than 4, WBC variable avoid when high risk of enterocentesis or severe pain |
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normals for Na K Mg pH and HCO3
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Na:130-142
K:2.8-4.6 Mg:1.3-2.5 pH:7.4 HCO3:22-30 |
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normal daily oral intake of fluids
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30-60ml/kg/day or 1L/hr/500kg
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primary ICF cation:
primary ICF anions: Primary ECF cation: Primary ECF anions: |
primary ICF cation:K(higher than other speices)
primary ICF anions:phosphate and proteins Primary ECF cation:Na Primary ECF anions:Cl and HCO3 sodium is a key player in maintenance of effective circulating volume |
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calculating dosage of HCO3 from BD
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BD x BWT(kg) x 0.3
only treat if acidosis is not responsive to fluids begin with replacing 1/4 of the deficit and repeat blood gas measurement |
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expected abnormalities in the colic
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Na and Cl generally WNL
Ca low K variable, low with anorexia, high with azotemia Mg low(50%) with concurrent low Ca or increased wigh MgSO4 therapy HCO3 usually low |
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anion gap
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(Na+K)-(HCO3+Cl)= AG
AG greater than 25 is a poor prognostic indicator |
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central venous pressure
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estimates perload and approximates the ratio of blood volume to blood volume capacity
useful for 1.monitoring propensity for edema in at risk patients 2.limited urine production w/diuresis 3.hypo-oncotic states 4.right heart failure normal adult=7-12cm H2O neonate=2-12cmH2O |
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Colloid oncotic pressure
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measure in patients that are hypoproteinemic and receiving crystalloid fluids or horses receiving synthetic colloids (not detectable by refractometery)
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normal adult urine production
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1ml/kg/hr
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prokinetics
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1.lidocaine
2.metoclopramide 3.erythromycin 4.neostigmine 5.acepromazine 6.cisapride |
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adhesion prevention
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NSAIDs
carboymethylcellulose seprafilm DMSO abdominal lavage |
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most common clinical sign for choke
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nasal discharge
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equine esophageal clinical anatomy
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crainal 2/3 straited muscle
common carotid, vagosympathetic trunk, and recurrent laryngeal n. course w/ esophagus dorsolaterally within the deep fascia of the neck. poorly developed vomiting reflex |
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treatment of choke non surgical
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xylazine
detomidine oxytocin remove all access to feed and water spontaneous resolution w/ or w/out sedation gental lavage with stomach tube, cuffed nasotracheal tube to prevent aspiration antibiotics higher chokes more likely to aspirate |
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choke treatment surgical
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only when absolutely necessary
esophageal lavage under general anesthesia, cuffed endotracheal tube placed in esophagus and nasogastric tube sealed inside to create pressure esophagotomy- when sticture present |
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clinical anatomy of SI
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25m
duodenum not accessible to visualization jejunum 70% can be exteriorized, long mesentery Ileum 50% can be exteriorized antimesenteric band (ileocecal band) |
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functional obstruction of SI
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proximal jejunitis/anterior enteritis
clinical signs: -Ileus -endotoxemia -pain responsive to NG decompression, then depression -leukocytosis with toxic left shift -fever -orange discolored or foul-smelling reflux -abdominocentesis:increased TP; normal WBC treatment: supportive care and gastric decompression |
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strangulating obstruction of SI most common site
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distal jejunum and ileum
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epiploic foramen entrapement
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can be left to right or right to left, left to right most common
mean age 9.8 years geldings and thoroughbreds overrepresented and cribbing horses Ileum most common segment involved |
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factors affecting success of small intestinal surgery
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1.ID and correction of primary problem
2.intra-op decompression of distended SI 3.resection of all compromised intestine 4.preservation of anatomic and physiologic continuity of intestine 5.rapid completion of surgery with minimal trauma 6.early return of intestinal function to normal use 7.appropriate post-operative support |
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sequence of events for SI resection/anastomomosis
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1.reduce incarceration and decompress if possible
2.ligate vasculature 3.luminal occlusion 4.transect and suture mesentery 5.resect bowel at distal end(at an angle to maximize luminal diameter and preserve blood flow to antimesenteric border) 6.decompress(if not done earlier) 7.perform anastomosis |
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large colon anatomy
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attached only at right colon
right ventral-sternal flexure-left ventral-pelvic flexure-left dorsal-diaphragmatic flexure-right dorsal-transverse colon. bands: 4-4-1-3-2 (RVC-LVC-LDC-RDC-small colon)-four on the floor 132. intercolonic mesentery |
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large colon impaction and fecaliths
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causes:
coarse feed, inadequate mastication, insufficient water. fecalith is a hard fecal ball common in young(<1yr) in old horses(>15yr) clinical findings: most common site is pelvic flexure-LVC, and junction bt RDC and transverse colon. mild intermittent colic HR mild increase Intestinal sounds usally present and associated with pain peritonel fluid usually normal or slight increase in TP if prolonged RDC impactions are often presumptive diagnosis based on persistent mild colic with little or no change in peritoneal fluid parameters in the face of normal rectal findings and lack of fecal production therapy: IV and oral fluids NSAIDs laxatives do not feed until impaction resolved if unresposive to medical terapy left paralumbar laparotomy under local anesthesia or ventral midline celiotomy under general anesthesia surgery rarely necessary for simple impactions, but often necessary for fecaliths prognosis:excellent |
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sand impaction
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cause:horses on pasture in areas with sandy soils, fed off ground
clinical findings: mild colic or severe acute pain if RDC/transverse colon completely obstructed, or accompanied by a colonic displacement tends to accumulate in RDC strech out or spend time laying down diarrhea low grade fever sand in feces peritoneal fluid often normal, but weight of sand makes enterocentesis likely resulting in peritonitis ausculted sand in ventral abdomin radiography is useful diagnostic aid treatment: psyllium and water via stomach tube oral and IV fluids analgesics large amounts of sand may require surgical removal form RDC and transverse colon through an enterotomy in the pelvic flexure prognosis: good in most complications:colonic rupture, severe colitis and endotoxemia |
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enterolithiasis
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cause: magnesuim and ammonium phosphate crystals around a nidus. most common in SW,CA,FL,IN. Arabians, Morgans, and American miniatures
alfalfa hay clinical findings: 1/3 history of recurring colic RDC at junction with transverse colon or small colon. most common site is the proximal small colon rarely palpable abdominal radiographs peritoneal fluid usually normal unless wall ischeimic treatment: surgery to decompress colon and cecum and then remove enteroliths with one or more flat sides are accompained by more enteroliths prognosis:very good |
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large colon volvulus
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cause:
occurs near the attachment of the colon to the cecum. often assoicated with parturtion, grass diet and or highly fermentable feeds most often in broodmares 8yr and within the first 3 months after foaling clinical findings: acute colic mesentery bt dorsal and ventral colon edematous on rectal severe pain if strangulating HR increased marked abdominal distention may have gastric reflux treatment: surgery recurrance 15% in brood mares may perform colopexy or resection prognosis: good to poor |
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left dorsal displacement,nephrosplenic entrapment
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cause:movement of the pelvic flexure or the entire left colo over nephrosplenic ligament
clinical findings: mild to moderate pain or intermittent painful episodes mm normal HR slightly increased colon palpated over ligament, bands of LVC running dorsocranially to the left kidney spleen enlarged and displaced ventral paracentesis may show blood due to splenic puncture left kidney behind spleen with colon gas medial to spleen on ultrasound treatment: 1.restict feed intake with spontaneous correction 2.IV phenylephrine to encourage spleenic contraction followed by light exercise 3.short term anesthesia, put horse in right lateral recombancey, elevate rear legs, dorsal recombacey with ballottement of abdomen, to left lateral recombancey, recover. concurrent recal palpation may help during roll 4.surgery, midline apporach, spleen is retracted medially, and colon is lifted up to free it, can laparospic ablation of the nephrosplenic space for repeat offenders prognosis:excellent |
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right dorsal displacement
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cause:pelvic flexure moves laterally around base of cecum and them may lie caudally in the pelvic inlet or continune cranially near the diaphragm, often complicated by 180 degree volvulus near the base of the cecum.
clinical findings: moderate pain slow development of systemic deterioration as the blood supply to displaced colon is usually maintained taenia of the colon running transversely across the pelvic inlet, can't fing cecum or pelvic flexure on rectal distended and tight abdomen elevation of liver enzymes from twisting of biliary system in chronic cases treatment: surgical intervention to locate pelvic flexure, exteriorize and empty if necessary, rotate left colon cecal base and correct volvulus if present prognosis: very good |
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nonstrangulating infarction
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cause:
either due to thromboembolism from stronglye larvae-induced damage to the cranial mesenteric artery or one of its branches, or local low blood flow state clinical findings: chronic intermittent dull pain without evidence of obstruction depressed endotoxemia very painful if complete infarction distended colon paracentesis-very high WBC COUNT and may RBC treatment: surgical resection of the infarcted tissue treatment of peritonitis analgesics IV fluids larvicidal therapy heparin or aspirin |
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cecal anatomy
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1m in length
mesentery attaches to dorsal body wall four bands -dorsal forms ileocecal band -lateral forms the cecocolic ligament -ventral -medial cecal artery(branch of ileocolic artery) |
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cecal impaction
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cause:
fibrous feed bad teeth young horses post surgery, other dz, or management change primary cecal motility disturbance clinical findings: off feed mild abdominal pain always at risk of cecal rupture use peritoneal fluid analysis and rectal exam findings to dictate therapy rectal exam is diagnostic-impaction on right side of abdomen w palpable ventral cecal band treatment: medical-IV and oral fluids surgery-typhlotomy or complete cecal bypass-ileocolic anastomosis |
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ileocecal, cecocecal and cecocolic intussesception
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cause and clinical findings:
uncommon tapeworms(anoplocephala perfoliata) may predispose to the condition wide variety of presenting clinical signs; acute, severe pain to mild, chronic dz treatment: surgery manual reduction and resction enterotomy of the RVC with resection |
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small colon impaction
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cause:
after diarrhea/colitis suggesting functional impairment leading to ileus and dehydration of ingesta clinical findings: pain mild to moderate but may be severe if obstruction complete rectal palpate of firm tubular impaction in small colon treatment: surgery is indicated if progressive pain results, peritoneal fluid abnormalities,or too firm to resolve medically pelvic flexure enterotomy and surgically assisted enemas complications: 50% positive for samonella post surgery diarrhea intraoperative and post operative treatment with DTO smectite(biosponge)may assist with prevention of post-op diarrhea |
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general features of small colon dz
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clinical signs may be insidious
often associated with endotoxemia evacuation of the large colon concurrently with relief of SC obstruction recommended esseential to preserve luminal diameter when performing an eneroromy of the small colon use strong,longer lasting absorbable suture for the enterotomy since firm digesta passes the site higher bacterial counts and increased collagenase activity present in the lumen of the small colon compared to the large colon more predisposed to adhesion formation than the large colon |
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small colon anatomy
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30cm
pelvic inlet to anus |
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classification of rectal tears
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gradeI:involve mucosa or mucosa and submucosa only
gradeII:defect in muscularis but mucosa intact gradeIII:mucosa, submucosa, and muscularis, leaving only serosa (a) or mesentery (b) gradeIV:all the way through |
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most common cause of rectal tears is _________ and most are __________
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palpation
dorsolateral |
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field management of rectal tears
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1.recognize and accept responsibility
2.caudal epidural and sedation 3.evacuate rectum 4.evaluate tear(bear arm) 5.pack rectum 3" stockinette with moistend roll cotton,dilute betadine and surgical gel, purse string rectum shut 6.tetanus toxoid and systemic antibiotics 7.ship to referral center 8.promptness of diagnosis and treatment essential |
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grade I recal tear treatment
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put on pasture
fecal softeners tetanus toxoid AB, NSAIDs recheck every couple of days |
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grade III and IV rectal tear treatment
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ventral midline celeotomy-evacuate colon/lavage abdomen
primary suture per rectum repeated manual evacuation loop colostomy end colostomy temp indewelling recatl liner in periparturient mares, rectal eversion and direct suturing |
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rectal prolapse types
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typeI: rectal mucosa only
typeII: all or part of the rectal ampulla(full thickness of rectal wall) typeIII: type II plus intussesception typeIV: rectum and variable length of small colon intussuscept through the anus |
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If rectal prolapse goes beyond _______ likely have torn mesenteric attachments which results in poor prognosis
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vulva
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perirectal absecess
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cause:
often unknown enemmas in foals feed/thermometer punture breeding injuries gravitation of gluteal abscess following IM injection clinical signs: low grade colic and depression, anorexia, decreased fecal production, tenesmus and fever diagnosis: palpation, ultrasound and percutanous or transrectal aspiration of pus treatment: establish drainage either percutaneously, per rectum, or vaginally depending on location. lavage abscess and adminster laxatives, appropriate antibiotics and NSAIDs. |
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rectal polyps and neoplasia
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polyps:
usually pedunculated remove by ligation and division neoplasia -types: most common are SCC and melanoma, with rectal adenocarcinoma and leiomyosarcoma less common. estimated that 80% of gray horses over 15years have melanomas treatment: dependent on the nature of the lesion. surgical excision, cryo, eletrosurgery, laser surgery, hyperthermia, chemotherapy, radiation therpay, immunotherapy, and combinations of these therapies |
