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26 Cards in this Set
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Which two diseases would be on a differential diagnosis list for equine urinary incontinence?
A - Equine degenerative myelopathy, Botulism B - Bracken fern toxicity, Equine encephalomyelitis C - Tetanus, West Nile virus encephalopathy D - Cauda equina neuritis, Herpesvirus myeloencephalopathy E - Nigropallidal encephalomalacia, Locoweed poisoning |
D - Cauda equina neuritis, Herpesvirus myeloencephalopathy
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Cauda equina neuritis and Herpesvirus myeloencephalopathy.
Horses with cauda equina neuritis (also called polyneuritis equi) have a progressive symetric LMN paresis of the tail, bladder, rectum, anal sphincter. Look for urinary incontinence, fecal retention and a weak or paralyzed tail. May see hind limb paresis if lumbosacral spinal cord is affected. Cranial nerves can also be affected, but typically cranial involvement is asymetric. May see temporal or masseter atrophy (Cranial Nerve 5), facial paralysis and exposure keratitis (Cranial nerve 7), head tilt or other CNS signs. Cause is unknown, may be an autoimmune process. Grave prognosis. Eventually euthanized. Herpesvirus myeloencephalopathy (EHV-1) may also present with urinary incontinence, but this is an uncommon manifestation of equine rhinopneumonitis. You would expect to hear a history of the more common EHV signs in other horses from the same farm, like respiratory disease ("snots") in foals and abortions in mares. Bracken fern toxicity (Pteridium aquilinum) causes thiamine deficiency in monogastrics (like horses) and bone marrow depletion, aplastic anemia and bladder tumors in ruminants. In horses, look for signs of anorexia, weight loss, incoordination and a crouching stance with feet placed wide apart. Horses may have trembling muscles when forced to move. |
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What is the clinical importance of the anatomic area indicated by the red arrow in this image?
A - Best surgical approach to mandibular sinus B - Most common site of tooth root abscess C - Good place to take a pulse D - Site of glossopharyngeal nerve block E - Upper limit of Viborg's triangle |
C - Good place to take a pulse
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A convenient way to take the pulse of a horse is to place two or three fingers over the facial artery, in the notch of the mandible just in front of the masseter (cheek) muscle.
Click here to see a to see a video of a vet taking a horse's pulse. There are 4 other places on a horse you can take a horse's pulse, but only one is also on the head: -Transverse facial artery (caudal to lateral canthus of the eye) -Median artery (proximal, medial forearm) -Great metatarsal artery (hindlimb, between McIII and McIV) -Digital artery (caudal pastern area, above hoof). Palpate the digital artery to feel the "bounding pulses" of equine laminitis. |
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A 3 year old Standardbred mare is presented with a 2-month history of exercise intolerance. Endoscopy shows the following image.
What is the diagnosis? A - Laryngeal hemiplegia B - Cleft palate C - Pharyngeal lymphoid hyperplasia (PLH) D - Epiglottic entrapment E - Dorsal displacement of soft palate |
E - Dorsal displacement of soft palate
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This is Dorsal displacement of the soft palate (DDSP). The caudal free margin of the soft palate moves dorsal to epiglottis, obstructing the airway and causing exercise intolerance. Rx conservatively, eliminating possible contributing diseases first (ie: rest, anti-inflammatories). Surgical treatments (Sternothyrohyoideus myectomy or soft palate resection) have mixed success rates around 50%.
Epiglottic entrapment is a big DDX for DDSP. Outline of the epiglottis can still be seen with epiglottic entrapment, UNlike DDSP. Cleft palate is a newborn disease. See difficulty suckling, dysphagia, MILK DRIPPING from NOSTRILS. Click here to see a Cleft palate. Euthanize if severe. Surgical closure if small. Laryngeal hemiplegia ("Roarers") present with inspiratory noise during exercise and exercise intolerance. Click here to see laryngeal hemiplegia. More than 90% occur on LEFT side. Rx is surgery. Pharyngeal lymphoid hyperplasia (PLH) is common. Thought to be a normal immunologic event in younger horses. |
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Foal heat diarrhea is typically associated with which choice?
A - Hemorrhagic enteritis B - Warm and humid weather C - Decreased suckling D - Neutropenia and fever E - Alterations in diet |
E - Alterations in diet
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Alterations in diet. Mild, self-limiting diarrhea in a foal 7-14 days of age is called foal heat diarrhea, because it coincides with the first estrus cycle post-foaling in the dam. Causes of foal heat diarrhea are poorly understood, but are thought to be related to a foal's tendency to start sampling hay and grain and practice coprophagy by 5 to 7 days of age, with consequent alterations in bacterial flora.
Foals are active and alert, with a normal appetite and vital signs. Clinical signs such as fever and lethargy, hematochezia or melena, and laboratory findings such as neutropenia are not routinely observed. |
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In which species is this a normal finding?
Click here to see image A - Pot belly pigs B - Ferrets C - Calves less than 4 weeks old D - Horses E - Goats |
D - Horses
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This is rouleau formation, a normal finding in many horses. (Note also the characteristic equine eosinophil in the center)
For normal goats, think of marked poikilocytosis. Remember Camelids (llamas, camels, alpaca) have ellipsoid red blood cells (RBCs). Remember that it is normal for birds and reptiles to have nucleated RBCs. |
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Damage to the left recurrent laryngeal nerve is associated with "roaring" in horses.
The left recurrent laryngeal nerve is a branch off of which cranial nerve? A - Hypoglossal (CN 12) B - Glossopharyngeal (CN 9) C - Facial (CN 7) D - Trigeminal (CN 5) E - Vagus (CN 10) |
E - Vagus (CN 10)
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Damage to the recurrent laryngeal nerve (a branch of the Vagus (CN 10)) causes laryngeal hemiplegia - a paralysis of the abductor muscle (dorsal cricoarytenoid muscle) controlling the glottic cleft in the larynx.
This allows the vocal fold (usually left side) to evert into the lumen of the larynx, obstructing airflow, leading to a roaring sound, and most importantly, slowing the horse. Follow this link to see an endoscopic image of laryngeal hemiplegia. If you have trouble remembering which cranial nerve is which, try this memory aid: 1. On -Olfactory 2. Old -Optic 3. Olympus -Oculomotor 4. Towering -Trochlear 5. Tops -Trigeminal 6. A -Abducens 7. Fat -Facial 8. Vested -Vestibulocochlear 9. German -Glossopharyngeal 10. Viewed -Vagus 11. Some -Spinal accessory 12. Hops-Hypoglossal |
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This radiographic image shows osteoarthritis of the lower hock joints of a horse.
Click here to see image What is the common name for this problem? A - Bone spavin B - Osselets C - Splints D - Bog spavin E - Ringbone |
A - Bone spavin
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This is bone spavin, the number 1 hock problem (tarsus) in horses, an osteoarthritis of the lower hock joints, usually affecting the distal intertarsal and tarsometatarsal articulations. Etiology not clear (several theories)-seen most in Standardbreds, Quarter Horses. If horse is lame, tends to drag toe.
Bog spavin is a chronic synovitis of the tibiotarsal joint- look for swelling and distention of the joint capsule. Follow this link to see a photo of bog spavin (lateral swelling, side of left tarsus). |
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A 4 month old filly is presented with a 4 day history of lethargy, heavy breathing, cough and decreased appetite.
T=104.9 F (40.5 C)..[N=99-101.3 F] HR=72 bpm.............[N=28-40] RR=44 brpm............[N=10-14] On lung auscultation asymmetrically-distributed crackles and wheezes are audible. Some areas have no breath sounds and a dull resonance on thoracic percussion. A lateral chest radiograph shows consolidated nodular lung lesions and mediastinal lymphadenopathy. Click here to see image What is the treatment of choice? A - Thoracocentesis and Amikacin. Saline cathartic if see diarrhea B - Erythromycin and Rifampin C - Chloramphenicol and Aminophylline D - Vancomycin. Atropine if see bronchspasm E - High dose procaine penicillin G after abcesses rupture |
B - Erythromycin and Rifampin
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Erythromycin and Rifampin. This is the clinical picture of a foal with pneumonia. In this case, a chest radiograph with consolidated nodular lung lesions and mediastinal lymphadenopathy is highly suggestive of Rhodococcus equi in a foal under 5 months of age. Treat long term 4 to 10 weeks with Erythromycin and Rifampin (expensive).
If a foal under 5 months with signs of pneumonia had diarrhea or gram positive pleomorphic rods (like Chinese letters) in a transtracheal wash, these signs would also suggest Rhodococcus. |
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Fractures of the proximal sesamoid bones in horses are often associated with damage to which structure?
What is the most appropriate diagnostic step? A - Superior check ligament B - Superficial digital flexor tendon C - Deep digital flexor tendon D - Suspensory ligament E - Impar ligament |
D - Suspensory ligament
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The suspensory ligament is most likely to be damaged with fracture of the proximal sesamoids due to its insertion onto these bones. Proximal sesamoid fractures are relatively common, caused by overextension. The prognosis for return to soundness is often predicated on the extent of the damage to the suspensory apparatus. Proximal sesamoid fractures and their attendant suspensory apparatus problems are the number one cause of racetrack deaths.
Click here to see a radiograph of a proximal sesamoid fracture. If you have trouble visualizing the anatomy involved in proximal sesamoid fractures, there are excellent pictures and a clinical summary in Guide to Equine Clinics: LAMENESS vol. II, pp. 116-117, Pasquinis, Jahn & Bahr. |
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Which nerve block would most specifically relieve lameness resulting from fracture of the navicular bone?
A - Abaxial sesamoidean B - Palmar digital C - Low four point D - Tibial and peroneal E - Median and ulnar |
B - Palmar digital
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The palmar digital nerve block (also called a PD or heel block) would anesthetize the palmar third of the foot, including the navicular bone. All of the other nerve blocks can desensitize the navicular bone too, but would not be as specific as a palmar digital nerve block.
The abaxial sesamoidean nerve block (ASNB, also called a pastern or foot block) would anesthetize the entire foot and much of the pastern. Sometimes an ASNB is needed to completely eliminate or diagnose navicular lameness, but it is less specific than the PD block. A low four point nerve block (Also called Low palmar or Volar block) would desensitize the fetlock and areas distal to it. The median and ulnar nerve block would anesthetize the carpus and areas distal to it. Click here to see forelimb nerve block landmarks. The tibial and peroneal nerve block would anesthetize the tarsus and areas distal to it. Click here to see pelvic limb nerve block landmarks. |
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In September, two Quarter Horse mares horses are presented that are pastured in a group of 5 in Oklahoma. The horses eat pasture grass supplemented by alfalfa hay and a small amount of grain.
One mare was found peracutely dead this morning. The other is depressed, anorexic and colicy. Physical exam reveals dark, congested mucous membranes with small ulcer-like erosions. The mare makes frequent attempts to urinate, yielding red urine (hematuria) with a urine specific gravity (USG) of 1.006. She makes repeated attempts to drink small amounts of water and keeps her muzzle submerged in the water trough. T=102.7 F (39.3 C)..[N=99-101.3 F] HR=40 bpm............[N=28-40] RR=20 brpm...........[N=10-14] Necropsy of the other mare shows that the stomach and bladder linings are irritated and hemorrhagic. What is the diagnosis? A - Sorghum cystitis B - Clostridium perfringens type A C - Arsenic toxicity D - Cantharidin toxicity E - Enzootic hematuria |
D - Cantharidin toxicity
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This is Cantharidin toxicity caused by blister beetles (Epicauta spp) which swarm in alfalfa hay during harvest.
Cantharidin is a potent irritant: see colic, renal disease, hematuria, peracute death. Follow this link to see a Merck image of Hemorrhagic gastritis. Follow this link to see a Merck image of Hemorrhagic cystitis. Enzootic hematuria is a cow disease thought to be caused by Bracken fern toxicity. In horses, see thiaminase-related STAGGERS with bracken fern and with Horsetail (Equisetum spp) on U.S. West Coast. Sorghum cystitis/ataxia is characterized by cystitis, urinary incontinence ("dribbling" ), posterior incoordination. |
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A newborn foal with hypoxic ischemic encephalopathy and a poor suckle response is being treated supportively with mare's milk via nasogastric tube, IV fluids with 5% dextrose and broad spectrum antibiotics.
What other treatment is often critical to caring for foals like this? A - Mannitol B - Famotidine C - Diazepam D - Isoxuprine HCL E - Metoclopramide |
C - Diazepam
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Seizure control with diazepam (0.11-0.44 mg/kg) is critical for foals with hypoxic ischemic encephalopathy(HIE). Repeat dosage as needed. If long-term control is required, try phenobarbital (2-10 mg/kg, IV, bid-tid).
Dimethyl sulfoxide (DMSO 1 g/kg in a 10% solution, IV) can be used to help decrease cerebral edema. Mannitol (1 g/kg as a 20% solution, IV) has been proposed to decrease cerebral edema, but must be used with caution: HIE foals often have subdural hemorrhage. In addition to supportive care (warmth, nutrition, fluids, colostrum/plasma), remember the three "S's" of HIE problem management-- Sepsis Seizures Self-trauma |
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A 4-year old quarterhorse mare is presented with a runny left eye and a urine-scalded perineum. No other horses on the farm are sick. Physical exam reveals a corneal ulcer and keratitis OS (left eye), and atrophy of the temporal and masseter muscles.
There is decreased perineal sensation, a weak tail and weak anal sphincter with retained manure. The horse is bright, alert and responsive. T=102.2 F (39.1 C)..[N=99.0-101.3 F] HR=40 bpm............[N=28-40] RR=12 brpm...........[N=10-14] Which one of the following choices is the most likely diagnosis? A - Equine degenerative myelopathy (EDM) B - Equine protozoal myelopathy (EPM) C - Nigropallidal encephalomalacia D - Botulism E - Cauda equina neuritis |
E - Cauda equina neuritis
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Horses with Cauda equina neuritis (also called polyneuritis equi) have a progressive symetric LMN paresis of the tail, bladder, rectum, anal sphincter. Look for urinary incontinence, fecal retention and a weak or paralyzed tail. May see hind limb paresis if lumbosacral spinal cord is affected.
Cranial nerves can also be affected, but typically cranial involvement is asymetric. May see temporal or masseter atrophy (Cranial Nerve 5), facial paralysis and exposure keratitis (Cranial nerve 7), head tilt or other CNS signs. Cause is unknown, may be an autoimmune process. Grave prognosis. Eventually euthanized. Herpesvirus myeloencephalopathy (EHV-1) may also present with urinary incontinence, but this is an uncommon manifestation of equine rhinopneumonitis. You would expect to hear a history of the more common EHV signs in other horses from the same farm, like respiratory disease ("snots") in foals and abortions in mares. |
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A 6-year old Standardbred jumper is presented with a 3-month history of poor performance and intermittent shifting hindleg lameness. On physical exam, there is poor muscling of the gluteal muscles and some asymmetry to the croup (rump).
The horse has a 7 cm. swelling over the hindquarters on the left dorsal side and shows pain and a reluctance to ventroflex the back when midline pressure is applied. On rectal palpation crepitation and shifting can be felt dorsally as the horse walks slowly forward. What is the diagnosis? A - Fibrotic ossifying myopathy B - Overlapping vertebral spinous processes C - Croup myopathy (longissimus dorsi, supraspinous ligament) D - Sacroiliac subluxation E - Coxofemoral luxation |
D - Sacroiliac subluxation
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Think of sacroiliac subluxation or sprain in an athletic jumping horse with:
--Intermittent hindlimb lameness localized in the croup (rump) --Evidence of back pain --Swelling over the tuber sacrale (hunter's bumps) --Crepitance felt rectally in the sacroiliac area. Horses with hunter's bumps can be sound if the injury has completely healed, but lameness can be observed if the injury is recent or has never resolved. Sometimes confused with stifle lameness. Coxofemoral luxation is rare in horses due to a deep acetabulaum and the presence of the accessory ligament of the hip, unique to horses. Overlapping vertebral spinous processes is a problem of thoracic and lumbar vertebra under the saddle area, seen in short-backed eventing horses (hunter/jumpers, dressage). Back muscle and ligament strain is the #1 cause of back pain in horses, accounting for 33% of cases. Most commonly associated with the longissimus dorsi muscle, sublumbar illiopsoas muscles and the supraspinous ligament and also seen in eventing horses. |
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A 3-year old Quarter horse/Appaloosa cross mare is presented on emergency because she collapsed in the last 30 minutes.
The mare is recumbent and weak, with respiratory stridor, muscle fasiculations, sweating, prolapse of the third eyelid and her lips pulled back spasmodically, like a grin. T=100.2 F (37.9 C)..[N=99-101.3 F] HR=24 bpm.............[N=28-40] RR=16 brpm............[N=10-14] The horse is hydrated and has had no recent history of colic. During the examination, she improves markedly and within 60 minutes stands and appears almost normal again with no treatment. What is the clinical diagnosis? A - Hyperkalemic periodic paralysis (HyPP) B - Equine degenerative myelopathy (EDM) C - Epilepsy D - Grass staggers E - Myasthenia gravis |
A - Hyperkalemic periodic paralysis
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This is likely to be Hyperkalemic periodic paralysis (HyPP), an autosomal dominant trait found in ~ 4% of Quarter horses.
Heterozygotes often have periodic episodes 15-90 min: prolapse 3rd eyelid, muscle fasiculations, collapse. 25% cases traced back to one stallion named "Impressive". Onset of signs unpredictable, and many triggers: diets high in POTASSIUM (>1.1%, ie: alfalfa hay, molasses, electrolyte supplements, kelp-based supplements). Fasting, anesthesia, heavy sedation, trailer rides, and stress can precipitate clinical signs. Grass staggers think "goose-stepping" (overstepping) from ergot on grass. EDM think ataxia in foals 6-8 mos. Epilepsy poorly documented in horses. Myasth. Gravis basically a dog disease. |
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A 4-year old thoroughbred mare is presented with a sudden onset of profuse, watery diarrhea and marked depression.
The mare has been intermittently treated with phenylbutazone over the last 2 months for minor lameness and was transported by trailer for 9 hours recently. On physical exam the horse is dehydrated, with slow capillary refill time, purplish mucous membranes and cold extremities. T=100.0 F (37.8 C)..[N=99-101.3 F] HR=48 bpm.............[N=28-40] RR=32 brpm............[N=10-14] PCV=65%................[N=32%-53%] The horse dies 3 hours later. On necropsy there is blood-stained fluid in the intestines and pronounced edema and hemorrhage in the wall of the large colon and cecum. Which one of the following choices is the most likely diagnosis? A - Sand enterocolopathy B - Nonsteroidal anti-inflammatory drug toxicosis C - Granulomatous enteritis D - Parascaris equorum infestation E - Colitis X |
E - Colitis X
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This is the clinical picture of colitis X, an acute to peracute-onset of lethal diarrheal disease of horses.
Look for shock signs, peracute severe diarrhea and a packed red cell volume (PCV) above 65%, and sudden death. The cause is unknown but stress (like transport) or surgery often precedes disease. This is a diagnosis of exclusion-if you rule out other peracute severe diarrheas (Salmonellosis, Potomac horse fever (PHF), Clostridial enterocolitis, Lincomycin/Tetracycline toxicosis), you are left with presumptive colitis X. |
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A 4-year old quarterhorse presents with a 3 week history of diffuse patchy alopecia on the ventral midline and face, including a "bulls-eye" lesion in the center of the forehead.
There is a mild conjunctivitis and uveitis OU (both eyes). A punch skin biopsy looks like the image below. What is the most appropriate treatment? Click here to see image A - Trichlorfon drench, antibiotic ophthalmic ointment TID B - Do nothing C - Ivermectin now, repeat in 4 months D - Topical DMSO, Oxybendazole q. 8 weeks E - Corticosteriods, benzimidazole-piperazine q. 12 weeks |
C - Ivermectin now, repeat in 4 months
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The treatment of choice for Onchocerca spp microfilaria is an avermection-family drug, with retreatment at 4 month intervals.Treated horses show marked improvement. Although adult filaria are not killed by avermectins, in practice most horses are free of disease within 6-12 months.
Adult filaria live in calcified nodules in the ligamentum nuchae and produce microfilaria that migrate to the ventral midline, face, neck, and chest. The resulting dermatitis is thought to be a hypersensitivity to microfilarial antigens. Accumulation of microfilaria in the eye may also lead to conjunctivitis and uveitis. Note that Culicoides spp (no-see-ums, biting midges) carry the onchocerca microfilariae, but do not cause the problems listed above themselves. Instead, biting midges cause sweet itch, a very pruritic warm weather dermatitis that is also secondary to hypersensitivity. Doing nothing is a poor choice in this symptomatic animal. Finding microfilaria in skin biopsies of asymptomatic horses is a common incidental finding. Because of this, some references debate the role of onchocera in the pathogenesis. It seems likely that variations in immune response play a role in severity of disease presentation. In humans, Onchocerciasis is a well known cause of hypersensitivity-related superficial keratitis (river blindness) and dermatitis. |
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An adult horse with clinical signs of voluminous gastric reflux, depression, colic, and fever is most likely suffering from which one of the following choices?
A - Proximal enteritis B - Ulcerative duodenitis C - Proliferative enteropathy D - Right dorsal colitis E - Cantharidin toxicity |
A - Proximal enteritis
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Proximal enteritis, or duodenitis-proximal jejunitis, is a clinical syndrome characterized by large volumes of gastric reflux resulting from excessive fluid and electrolyte secretion into the small intestine and small intestinal inflammation and edema.
Laminitis is an important potential sequela. The cause is unknown but several bacteria and toxins including Clostridium difficile, Clostridium perfringens, Salmonella, and fumonosin B1 mycotoxins have been implicated. Ulcerative duodenitis is a disorder of foals resulting in fever, colic, diarrhea, and delayed gastric emptying. Lawsonia intracellularis causes proliferative enteropathy in foals and weanlings, a disease characterized by hypoproteinemia, diarrhea, chronic ill thrift, and ventral edema. Right dorsal colitis is typically a result of non-steroidal anti-inflammatory drug toxicity and results in hypoproteinemia and colic. Cantharidin toxicity (blister beetles, Epicauta spp.) causes a wide range of clinical signs predominated by profuse diarrhea, stranguria and pollakiuria, and colic. |
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An adult horse with clinical signs of voluminous gastric reflux, depression, colic, and fever is most likely suffering from which one of the following choices?
A - Proximal enteritis B - Ulcerative duodenitis C - Proliferative enteropathy D - Right dorsal colitis E - Cantharidin toxicity |
A - Proximal enteritis
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Proximal enteritis, or duodenitis-proximal jejunitis, is a clinical syndrome characterized by large volumes of gastric reflux resulting from excessive fluid and electrolyte secretion into the small intestine and small intestinal inflammation and edema.
Laminitis is an important potential sequela. The cause is unknown but several bacteria and toxins including Clostridium difficile, Clostridium perfringens, Salmonella, and fumonosin B1 mycotoxins have been implicated. Ulcerative duodenitis is a disorder of foals resulting in fever, colic, diarrhea, and delayed gastric emptying. Lawsonia intracellularis causes proliferative enteropathy in foals and weanlings, a disease characterized by hypoproteinemia, diarrhea, chronic ill thrift, and ventral edema. Right dorsal colitis is typically a result of non-steroidal anti-inflammatory drug toxicity and results in hypoproteinemia and colic. Cantharidin toxicity (blister beetles, Epicauta spp.) causes a wide range of clinical signs predominated by profuse diarrhea, stranguria and pollakiuria, and colic. |
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In which respiratory virus infecting horses is antigenic drift most important in the development of novel strains?
A - Equine influenza virus B - Equine papillomavirus C - Equid herpesvirus-4 D - Equid herpesvirus-1 E - Equine adenovirus |
A - Equine influenza virus
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Antigenic drift is most important in the epidemiology of equine influenza.
Point mutations in the genes for hemagglutinin and neuraminidase cause changes in these surface proteins that can lead to the development of new virus strains not recognized by antibodies to earlier strains. Because influenza is an RNA virus without proofreading ability, mutations can occur more rapidly with flu than mutations seen in DNA viruses like equid herpesviruses and adenoviruses. |
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Which one of the following choices is a side effect of xylazine in horses?
A - Sweating B - Hypoxemia C - Excitement D - Tachycardia E - Diarrhea |
A - Sweating
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Sweating is seen in horses sedated with xylazine and all alpha-2 agonists. The specific mechanism is not known, but interference with thermoregulation in the hypothalamus is thought to be involved.
Although respiratory rate and volume are both decreased, hypoxemia does not develop in normal horses. Alpha-2 agonists cause a reflex bradycardia - the heart rate decreases in response to the high blood pressure caused by vasoconstriction caused by alpha-2 receptor stimulation. This is a baroreceptor-type response of the cardiovascular system to maintain blood pressure within the normal range. Alpha-2 agonists cause ileus that can be significant with high doses and in combination with other anesthetic agents, but does not cause diarrhea. Analgesia, muscle relaxation, ataxia, and dose dependent sedation are also seen, not excitement. |
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A herd of 12 multiparous broodmares housed on a 25 acre pasture in the southeastern United States are having reproductive problems.
Of the three mares that have foaled so far this year, none have produced milk. Another mare is now 12 months in foal and has no udder development. Which one of the following choices is the most likely diagnosis? A - Malnutrition B - Fescue toxicity C - Retained placentas D - Placentitis E - Mastitis |
B - Fescue toxicity
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Ingestion of fescue grass contaminated with the endophyte fungus Acremonium coenophialum causes agalactia, thickened placentas, and prolonged pregnancy in mares by suppressing prolactin release. Toxicity is most significant in the last 90 days of gestation
Mares should be removed from fescue pastures (and not fed fescue hay) for the last 90 days of gestation to reduce the incidence of fescue-associated problems. Treatment with domperidone can help affected mares produce milk. Mares with malnutrition are more likely to abort than carry a pregnancy over term. |
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A mare presents with a history of herding and mounting other mares in a broodmare group. During the physical exam, the mare is very unruly and tries to bite and kick.
After sedation, rectal palpation findings reveal a walnut sized, smooth left ovary and a softball sized right ovary. No ovulation fossa is palpable on the right ovary. Which one of the following choices is the most likely diagnosis for the right ovary? A - Cystic ovary B - Granulosa cell tumor C - Anovulatory follicle D - Hematoma E - Transitional status |
B - Granulosa cell tumor
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Granulosa cell tumors (GCTs) secrete reproductive hormones such as testosterone, inhibin, and estrogen. Testosterone causes the mare to show stallion-like behavior, while estrogen causes persistent estrus
Approximately 50-90% of mares with GCTs have elevated testosterone and over 85% of mares with GCTs have high inhibin. With GCTs the contralateral ovary tends to stop producing follicles and resembles an ovary during anestrus. |
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You are presented a healthy 10 yr old maiden mare for breeding evaluation in January. On rectal palpation, both ovaries have multiple, small (less than 15 mm) follicles and no corpus lutea. The uterus is flaccid with no edema.
Which one of the following choices is the most likely explanation of the findings in this mare? A - The mare is in diestrus B - The mare is too old and now is infertile C - Early pregnancy D - Seasonal anestrus E - Estrus has just passed |
D - Seasonal anestrus
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Mares are seasonal breeders and enter anestrus in the short day months, late fall and winter. In anestrus the ovaries are inactive with small follicles and no corpus lutea.
During estrus, the uterus softens and multiple follicles form on the ovaries. During pregnancy the uterus has good tone. |
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A 5 year old quarterhorse is presented with a depigmented hyperkeratotic plaques localized to the concave aspect of both ears.
What message should be communicated to the owner? A - Typically secondary to underlying immunosuppression B - Surgical removal is curative C - Need to check the pasture for photosensitizing plants D - Lesions usually persist for life E - Do not breed this horse |
D - Lesions usually persist for life
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Equine aural plaques (papillary acanthoma, ear papilloma) typically persist for life.
Equine aural plaques are caused by a papillomavirus and thought to be transmitted through mechanical transmission by biting Black flies (Simulium spp.) There is no specific treatment. Prevention includes application of fly repellent and stabling the horse during the Black fly's feeding times (dusk and dawn). |
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An adult horse with clinical signs of voluminous gastric reflux, depression, colic, and fever is most likely suffering from which one of the following choices?
A - Proliferative enteropathy B - Proximal enteritis C - Cantharidin toxicity D - Ulcerative duodenitis E - Right dorsal colitis |
B - Proximal enteritis
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Proximal enteritis, or duodenitis-proximal jejunitis, is a clinical syndrome characterized by large volumes of gastric reflux resulting from excessive fluid and electrolyte secretion into the small intestine and small intestinal inflammation and edema.
Laminitis is an important potential sequela. The cause is unknown but several bacteria and toxins including Clostridium difficile, Clostridium perfringens, Salmonella, and fumonosin B1 mycotoxins have been implicated. Ulcerative duodenitis is a disorder of foals resulting in fever, colic, diarrhea, and delayed gastric emptying. Lawsonia intracellularis causes proliferative enteropathy in foals and weanlings, a disease characterized by hypoproteinemia, diarrhea, chronic ill thrift, and ventral edema. Right dorsal colitis is typically a result of non-steroidal anti-inflammatory drug toxicity and results in hypoproteinemia and colic. Cantharidin toxicity (blister beetles, Epicauta spp.) causes a wide range of clinical signs predominated by profuse diarrhea, stranguria and pollakiuria, and colic. |
