HORSES Flashcards

Question

A one-week old female foal is having eye problems - blepharospasm and epiphora. On exam the lower eyelid margin is inverted inward, what is the diagnosis? a. ocular onchocerciasis b. entropion c. fungal keratitis d. ectropion e. chelazion

Answer 1

Entropion; this is a common condition in foals where their lower eyelid is inverted and can cause conjunctivitis or keratitis. The conditon will usually correct sponataneously but sometimes will require treatment to evert the lid. One method for this is to use a local anesthetic, mechanically evert the lid, and staple it. Alternatively, surgical correction can be performed, but is rarely indicated. Ectropion is the opposite condition where the eyelid everts out and can lead to exposure keratitis, but this is uncommon in horses. Ocular onchocerciasis is caused by microfilariae and is seen in about 50% of horses with cutaneous onchocerciasis.

Answer 2

Equine Degenerative Myeloencephalopathy (EDM); the clinical signs are most consistent with EDM. Cervical Vertebral malformation (Wobblers) is also a possibility, but was not an option. The cause of EDM is unknown, but this disease typically affects young horses (<2-3 years of age; but older horses can develop the disease). Clinical signs are aa result of diffuse neuronal fiber degeneration of various portions of the central nervous system. This disease has been associated with low serum vitamin E concentrations, suggesting the oxidative damage may play a role in the development of disease. EMND is typically associated with muscle tremors, shifting of weight while standing, muscle atrophy and recumbency. Botulism is assoicated with generalized muscle weakness. Cauda equina syndrome causes analgesia of the perineum. EPM can cause a range of clinical signs, but is typically with asymmetric neurologic deficits.

Answer 3

Myotonia; these clinical signs and findings are consistent with a horse with myotonia. Etiology is not completely understood, but a fenetic component is suspected. The 'dive bomber' sound heard on EMG is produced by repetitive firing after contraction of affected muscle fibers and is essentially pathognomonic for myotonia. Hyperkalemic periodic paralysis would be seen in Quarter Horses, Paint Horses, and Appaloosa horses rather than Thoroughbreds.

Answer 4

Neutrophilic inflammation; in health BAL fluid primarily consists of macrophages. However, in RAO, neutrophils are the predominant cellular finding. RAO typically affects older horses aand is aa response to environmental allergens. The classic case is the horse that is stalled in the winter and possibly house in the vicinity of hay storage. When the horse is exposed to hay allergens (via inhalation), bronchoconstriction and neutrophilic inflammation occur.

Answer 5

Thelazia; genus of nematode worms (eyeworms) which are found in the ocular tissues. Adults are usually found in the eyelids, tear glands, tear ducts, or the nicitating membrane. They may be found in the eyeball itself under the conjunctiva or in the vitreous. Thelazia are transmitted by Diptera (flies) which do not bite but feed on tears. Toxocara, which causes ocular migrans, usually causes granulomas which may be seen in the retina and appear more circular.

Answer 6

It is best to wait for 30 days after resolution of signs and then perform 3 consecutive weekly negative nasopharyngeal cultures; strangles can be a difficult disease to control and vigilant preventative measures are necessary to minimize transmission as a small percentage of horses develop persistent infection of the guttural pouches associated with purulent inflammation or the presence of chondroids. These carriers can be detected either by culture or by detection of S. equi DNA using the polymerase chain reaction (PCR) test. PCR is a more sensitive test but also more expensive and may have false positives in recently infected horses due to residual DNA from dead bacteria. If an animal tests positive an endoscopic evaluation of the guttural pouch is recommended, chondroids removed, and guttural pouches treated by flushing and infusing 5 million units of penicillin G in 3% gelatin. In additon, these horses should be treated with penicillin G IM for 7 days, isolated for 30 days, and then retested with the 3 consecutive series of nasopharyngeal swabs and cultures. Vaccine against S. equi are available.

Answer 7

Cyanide toxicity; cyanide does not allow hemoglobin to release oxygen, thus causing the cherry red lips. It is found in cherries, chokecherries, arrow grass and Sudan grass. Large amounts must be consumed. There is a bitter odor of almonds to the GI tract with this toxicity. Treatment is sodium nitrate and sodium thiosulfate. Prognosis is poor due to rapid onset. Carbon monoxide can cause cherry red mucous membranes, but would not cause the almond smell.

Answer 8

Neorickettsii risticii, Supportive test - a PCR of blood or feces; the causative agent of Potomac ?Horse Fever (PHF). The clues that indicate PHF are the time of year (typically occurs in summer in northern states), the high fever and diarrhea, presence of laminitis. The horse is also dehydrated and has a profound leukopenia.

Answer 9

Radial and 3rd carpal bones; most carpal fractures in horses occur at the dorsal aspect of the carpal joint, particularly at the radial and 3rd carpal bones. Both chip and slab fractures may occur. These fractures usually result in immediate swelling and severe lameness. Diagnosis is based on radiographs and arthroscopic surgical repair is frquently the treatment of choice.

Answer 10

Stallion positive for Qa and mare negative for Qa; for neonatal isoerythrolysis to occur, the mare must develop antibodies to the foal's RBC antigens. Aa and Qa are the two antigens most frequently implicated in this condition. For this condition to occur, the foal must inherit the Aa or Qa antigen from the stallion, and the mare must be negative for the antigen. Then, when the mare becomes exposed to the foal's RBC antigens she makes antibodies. When she passes these antibodies to the foal through colostrum an acute hemolytic event will occur in the foal. In most cases the first time a mare has a foal with the antigen she will not produce sufficient antibodies to cause severe damage tot he foal. Therefore, this condition is usually seen in multiparous dams or in mares that have previously had a blood transfusion that exposed them to the RBC antigen.

Answer 11

West nile Encephalitis (WNV); erum immunoglobulin M (IgM) capture ELISA; the mosquito born flavivirus that affects horses in multiple areas of the US. Clinical signs are variable and can be mild (muscle fasiculations, slight ataxia) to severe (recumbency). Of note, muscle fasiculations is somewhat characteristic of WNV, but fever may be detected in all patients. A readily available diagnostic test is the serum IgM capture ELISA which will detect infection, even in the face of vaccination. There is a vaccine available for WNV, making the clinical presentation less common.

Answer 12

it is effective at diagnosing infection in chronic asymptomatic carriers; the Coggin's test is a test for antibody; therefore it carries several drawbacks/limitations. In acute episodes of equine infectious anemia (EIA), there is often not yet adequate production of antibody to detect by this test. In foals, false positives can occur due to acquisition of the antibody in colostrum. Persistently infected horses constitute the majority of cases, and because they are under constant antigenic stimulation, they maintain aantibody production and can be very accurately diagnosed with the condition by the Coggin's test.

Answer 13

A defect in endochondral ossification; osteochondrosis develops when there is an abnormal endochondral ossification resulting in the production of a cartilaginous flap within a joint. In young horses, a diagnosis is frequently made when first training. Severity of lameness can vary greatly. Osteomyelitis, trauma, and septic arthritis may be good differentials.

Answer 14

Inhalation; EHV-1 or equine viral rhinopneumonitis is a rapidly-spreading disease that is spread by inhalation directly or indirectly from infected nasal discharge, aborted fetuses or placenta. EHV-3, the cause of equine coital exanthema is spread venereally. Both EHV-1 and EHV-4 are cause of rhinopneumonitis, but they are very important because they also result in abortions. EHV-1 is also assoicated with myeloencephalitis and has resulted in various outbreaks in the U.S and abroad. EHV-1 is the main cause of paresis, abortions, and neonatal foal deaths.

Answer 15

Tendonitis; the intermittant lameness and bulge at the metacarpals are classic for bowed tendon or tendonitis.

Answer 16

Combined immunodeficiency; any arabian foal with persistent infection should be suspected of having this heritable immunodeficiency of B and T lymphocytes. Typically, foals with CID do not demonstrate evidence of repeated infection until maternal antibodies begin to wane. There is no treatment for this disease.

Answer 17

Sacroiliac luxation; jumping horses are commonly affected. The short strided gait is consistent with but not specific for this condition. The raised croup differentiates sacroiliac luxation from other options in this case. Upward fixation of the patella is not a traumatic condition as you should suspect based on the history. It does cause a short strided gait and toe-dragging. The tell-tale sign of this conditionis a hind limb in rigid extension that is unable to flex. Gonitis is a term indicating stifle arthritis that is nonspecific to the underlying cause. Stringhalt is involuntary flexion of the hind limb and is usually bilateral. Stringhalt is treated with lateral digital extensor tenectomy. A ruptured peroneus tertius is characterized by the ability to simultaneously extend the hocke and flex the stifle.

Answer 18

Systemic antibiotics; stretococcus equi ssp. equi is the agent causing strangles in horses. When they have lymph node abscessation, antibiotivs are contraindicated because they will prolong the course of the disease but will not eliminate it. Because this disease is spread by direct contact, isolation of the horse is important. To obtain a definitive diagnosis, the lymph nodes could be aspirated. The treatment is to lance the abscesses ventrally and dispose of the material to prevent spread of the organism.

Answer 19

application of horse shoes; laminitis is an inflammatory conditoin of the lamina in one or more feet of a horse. It is often a manifestation of systemic disturbances such as endometritis and salmonellosis. A high carbohydrate diet (carbohydrate overload), excessive weight bearing on an individual let, and corticosteroid administration also predispose a horse to laminitis.

Answer 20

Anaplasma phagocytophilum; (previously known as Ehrlichia equi). Anaplasma phagocytophilum infection can cause morulae to be present in neutrophils and eosinophis. Neorickettsia risticii (PHF) can cause morulae in monocytes but these are rarely seen on blood smears. Borrelia organsims are not seen in the peripheral blood and herpes inclusion bodies are intranuclear and would not be seen in a blood smear.

Answer 21

Cranial nerves VII and VIII (left side); fracture of the basisphenoid bone; this is a common injury when a fractious young foal rears up and falls backward on the poll. The basisphenoid bone becomes injured resulting in injury to cranial nerves VII and VIII. Damage to the facial nerve results in the muzzle deviation (opposite direction of the side of injury, in this case deviation to the right), ptosis of the left eye and drooping of the left ear. Damage to the vestibular nerve results in head tilt.

Answer 22

345 days; gestation can range from 330-360 days. Artifical lighting is often used in mid-December to promote estrus to occur in mid-February to increase the likelihood the horses will foal in mid-January which is the best time for race horses (since all horses have a January 1st birthday). Most foals are considered premature if born prior to 320 days and prolonged gestation is associated with greater than 365 days.

Answer 23

0-4 day old foals; in utero, the foal is protected from the mare's antibodies due to epitheliochorial placentation. The foal takes in colostrum during it's first 24 hours of life from the mare and develops the condition fairly acutely. Remember NI develops because the newborn foal expresses alloantigens on its RBCs inherited from the sire that the mare does not have. If the mare becomes sensitized to the sire's specific antigen, maternal antibodies are produced and absorbed by the foal soon after birth. This subsequently results in lysis of the RBCs. Pre-parturient blood testing between the mare and stallion may help in identifying the likelihood of this occurring.

Answer 24

ruptured longus capitis; the longus capitis and rectus capitis ventralis insert onto the basisphenoid and occipital bones. Rupture is usually caused by rearing over backwards. Epistaxis and varying degrees of brainstem signs are typically seen. Treatment for a ruptured longus capitis is primarily symptomatic and consists of stall rest and antibiotics to prevent secondary infection. Prognosis depends on the severity of neurological damage. Ethmoid hematoma is a progressive and locally destructive mass of the nasal passages or sinuses. This disease process could cause epistaxis but is not consistent with the recent trauma or the endoscopic findings in this case. Maxillary fracture would likely result in additional clinical signs at the fracture site and would not explain the brainstem signs or endoscopic findings. The maxillary vein is a branch of the external jugular vein. Traumatic laceration is very uncommon and depending on the location of the laceration, would cause external hemorrhage rather than epistaxis.

Answer 25

A normal finding. The equine tapetum is penetrated by small choroidal vessels that appear as dark dots. These are sometimes affectionately referred to as the stars of Winslow.

Answer 26

Pituitary Pars Intermedia Dysfunction (Cushing's); this condition is a result of hypertrophy, hyperplasia and micro- or macroadenoma of the pituitary pars intermedia that secretes increased amounts of propiomelanocortin peptides. Adjacent pituitary tissues are compressed and secrete less of some other peptides. Data suggests that horses with this disease have hypothalamic dysfunction and decreased amounts of dopamine.

Answer 27

SCC; presenting signs are weight loss and colic

Answer 28

Rhodococcus equi pneumonia; R. equi is the most likely cause resulting in pulmonary abscess formation that may be noticed on thoracic US. In the US, the capsular structure with an anechoic center represents a fluid-filled abscess. R. equi is typically observed in older foals (2-6 months of age) and demonstrates a slow insidious onset characterized by some or all the following findings: weight loss, fever, cough, nasal discharge, increased respiratory effort, and ill-thrift. US of the chest can provide a quick screening test for foals with R. equi pneumonia. All the other pathogens can cause pneumonia but are not classically associated with abscess formation.

Answer 29

perineum and tail base; melanomas occur in up to 80% of gray horses. They occur most commonly on the perineum and tail base but can arise anywhere on the body. Most melanomas of gray horses are benign with varying degrees of invasiveness. They have potential to develop into malignant tumors. Treatment includes surgery or cryosurgery. Horses that develop one melanoma are predisposed to developing others in the future.

Answer 30

elevation in serum triglycerides, gamma glutamyl transpeptidase (GGT), and sorbital dehydrogenase (SDH) suggestive of hyperlipemia and hepatic lipidosis; unlike other larger sized horses, minis are susceptible to the development of hyperlipidemia and hepatic lipidosis as a result of anorexia; the anorexia typically results from a primary disease, in this case mild colitis. Because of the negative energy balance, fats are mobilized in excess resulting in the opaque appearance of the serum. AKI is associated with hyperkalemia and equine Cushing's syndrome is associated with hyperglycemia.

Answer 31

Sheared heels; which is an asymmetry of the heels that is acquired due to imbalance of the foot resulting in one side of the heel contacting the ground before the other. This creates a shearing force and results in asymmetrical growth. Sheared heels are the best treated with repeated corrective trimming of the hoof and application of supportive bar shoes. The prognosis is good when the condition is corrected before additional complications arise. Seedy toe is characterized by a change in the character of the horn such that the inner surface is crumbly and there may be a cavity due to loss of substance. Scratches is a condition of chronic seborrheic dermatitis of the palmar/plantar aspect of the pastern. Club foot is a condition seen in horses secondary to contracture of the distal interphalangeal joint leading to a steep hoof wall and shortened toe. Gonitis is a term indicating stifle arthritis that is nonspecific to the underlying cause.

Answer 32

Sorbitol Dehydrogenase (SDH) and Gamma Glutamyl Transferase (GGT)l; SDH is found in the liver of all animals - an increase in serum SDH concentration suggests hepatocellular injury. Elevation in serum GGT is predominantely associated with biliary epithelial cells and is also liver specific. The other enzymes may be increased with liver disease, but may also arise from bone (ALP) or muscle (ALT, AST)

Answer 33

Obstruction; a pH that is greater than 5 suggests that small intestinal contents are refluxing into the stomach, resulting in an increased pH. Small intestinal ileus is another differential but was not an answer choice.

Answer 34

ruptured prepubic tendon; this tendon courses along the ventrum and provides the major support for all the structures in the equine abdomen. It can rupture in late pregnancy, especially in obese draft mares. This is usually preceded by ventral swelling. If such swelling is noted, preventative measures should be taken such as restricting activity and possibly slinging the abdomen to provide support. This condition is very painful to the mare and may affect the ability to increase intra-abdominal pressure during parturition. Assisted parturition by a veterinarian should be strongly considered. A body wall hernia may also result in similar signs as a ruptured prepubic tendon.

Answer 35

Rhodococcus (Corynebacterium) equi; the signalment and clinical signs are most consistent with Rodococcus equi infection. The radiographic finding of an alveolar pattern with multiple nodular regions is very indicative of Rhodococcus infection causing suppurative pyogranulomatous pneumonia. The nodular densities are Rhodococcus abscesses. Pneumonia from the other diseases in the answer choices might have an alveolar pattern on thoracic radiographs but would not be likely to have nodules. Pneumocystis is an opportunistic pathogen that can infect foals that are immunocompromised and cause interstitial penumonia.

Answer 36

Strongylus vulgaris; migration of the larvae of Strongylus vulgaris and the corresponding immune response can result in thrombosis of the cranial or anterior mesenteric arteries leading to colic and infarction of the bowel. Paarascaris equorum causes colic in foals by causing intestinal impaction. Strongyloides westeri is a cause of foal heat dirrhea and caan migrate through the lungs causing damage. Dictyocaulus is a lungworm. Draschia megastoma is another migrating parasite that can cause focal granulomas in the lung.

Answer 37

Proprioceptive deficits; these are not usually present with botulism because it is not a myelopathy but is a neuromuscular disease. The toxin blocks release of acetylholine at neuromuscular junctions. The protruding tongue is a common early sign of botulism. Mydriasis occurs due to decreased pupillary response to light. Dyspnea occurs from paralysis of the diaphragm.

Answer 38

Atrial fibrillation; is most commonly associated with exercise intolerance. There is no underlying rhythm to the heart beats. The ECG reveals absence of P waves and widely variant Q-Q intervals. There may or may not be a serious underlying heart disease.

Answer 39

Equine protozoal myeloencephalitis; can affect any age horse and is caused by Sarcocystis neurona. It should be suspected in this caase due to the asymmetry of clinical signs, as it is a multifocal disease of the CNS. Wobbler syndrome and degenerative myeloencephalopathy are diseases seen primarily in younger horses (<3-4 years of age). Degenerative myelopathy causes symmetrical ataxia. Cauda equina neuritis typically causes tail rubbing and urinary and fecal incontinence.

Answer 40

Less than 2.5 mmol/L; it is important to remember a general reference range for all diagnostic laboratory data; lactate is commonly performed on a hand-held lactometer that does not provide a reference range. Lactate is produced from pyruvate in anaerobic environments to keep the process of glycolysis running. When a horse/foal is hypovolemic, blood lactate may increase because of poor blood perfusion to the body. Several studies have investigated blood and peritoneal lactate as a means of predicting survival in neonatal sepsis and equine colic. It may be necessary to look up these studies if you want exact findings, but not surprisingly, the higher the lactate, the poorer the prognosis.

Answer 41

osteolysis; navicular syndrome is a chronic degenerative condition of the navicular bursa and navicular bone. The precise etiology is unknown and is likely multifactorial involving the navicular bone, the suspensory ligament, the coffin joint, the navicular bursa, and the deep digital flexor tendon. Osteophyte formation, bony remodeling, and enlarged vascular channels are the hallmark radiographic findings in horses with navicular syndrome. Osteolysis is generally not a component of this conditon.

Answer 42

Bog spavin; also known as tarsal hydrarthrosis, is often due to poor conformation and can result in increased synovial fluid formation. Both hindlimbs are usually affected. The horse is usually not lame from this condition. Distension may spontaneously appear and disappear in young horses. Bone spavin is osteoarthritis of the hock. Curb is thickening of the plantar tarsal ligament due to strain. Sweeney is supraspinatous contracture.

Answer 43

Papillomavirus is believed to play a role in the pathogenesis; sarcoids are one of the most common tumors in horses. They are considred non-metastatic tumors in virtually all cases. For this reason, small lesions are sometimes treated with benign neglect, but they are not expected to regress. More advanced lesions or tumors in certain sites do need to be treated more aggressively. Unfortunately, no single treatment is universally effective. Recurrence rates after surgical excision are approximately 50%. Although there is still controversy surrounding this issue, either bovine papillomavirus or an equine variant is thought by many to play a role in development of these tumors.

Answer 44

Hepatic failure with secondary hemolysis; when the liver fails in the horse, it often results in a hemolytic crisis as RBCs become more fragile due to toxic metabolites in the blood. This crisis is usually fatal and indicates terminal stages of liver failure in the horse.

Answer 45

Splints; or metacarpal exostosis which involves periostitis of the interosseous ligament between the third and second metacarpal (or metatarsal) bone. Treatment usually involves rest and anti-inflammatory medications, although if the bony exostosies impinge on the suspensory ligament, surgical removal of the proliferative tissue may be indicated. Sidebone refers to ossification of the alar cartilage of the coffin bone. High ringbone refers to osteoarthritis of the proximal interphalangeal (pastern) joint. Osselets are inflammation of the periosteum on the dorsal distal epiphyseal surface of the third metacarpal bone and fetlock joint. Thoroughpin is the term for effusion of the tarsal sheath (sheath of the deep digital flexor).

Answer 46

Granulosa-thecal cell tumor; the clinical signs and palpation findings are both consistent with this diagnosis. The other choices listed may create a palable ovarian mass, but would not caause atrophy of the contralateral ovary and should not cause infertility.

Answer 47

Appaloosa; equine night blindness is a congenital disease that is bilateral and nonprogressive, wherein horses have variable degrees of decreased vision in the daark. Recurrent uveitis is a very important condition in the horse and is actually the most common cause of blindness in the horse. Appaloosas are overrepresented, but the disease can occur in any breed. It is thought to be related to certain paathogens including Leptospira, Onchocerca, Toxoplasma, Brucella, and other infections, but these relationships are poorly characterized. Affected horses have recurrent bouts of inflammation, and each episode causes progressively worsening intraocular damage. The condition is sometimes referred to as moon blindness.

Answer 48

12%; a horse requires about 1.3g of protein per kilogram body weight or about 40g of protein per 1000 calories. This corresponds to about 12% of dry matter intake. Obviously, other factors play some role, including the quality of the protein source. /in general, excess protein does not cause horses any health problems, but it can be an unnecessary expense for owners. Too little protein can result in malnutrition problems.

Answer 49

Sarcocystis neurona; clinical signs of the disease vary in that they may be focal, multifocal, or diffuse in nature. One may observe focal muscle atrophy, and a neurologic exam may show ataxia and incoordination of all four limbs. However, you may only see one limb affected also. Muscle atrophy is most commonly seen in the quadriceps and gluteal regions of the hindlimbs. Horses may also have brainstem involvement and therefore exhibit a head tilt, facial paralysis, circling, and acute recumbency. Neospora caninum has recently been found as a cause of abortion in cattle. Toxoplasmosis can result in abortion and stillbirth in sheep. Other clinical sings seen with Toxoplasma gondii include diarrhea, cough, dyspnea, seizures, chorioretinitis, meningoencephalomyelitis, and myositis. Animals affected are usually immunocompromised and usually include young kittens, pigs, and dogs. EHV-1 is mainly recognized for resulting in respiratory disease and sometimes may cause abortion and infrequently neurologic disease.

Answer 50

fetal or neonatal hemoabdomen; all other choices listed were potential disease manifestations of MRLS. The exact pathogenesis of MRLS is still unknown, but the presence of eastern tent catipillars was strongly associated with the disease.

Answer 51

Synergistic hemolysis inhibition test; other clinicopathologic data that would support an internal abscess would include leukocytosis, hyperfibrinogenemia and hyperglobulinemia. A KOH test is used to diagnose dermatophytes. The zinc sulfate turbidity test evaluates for failure of passive transfer. The Coggin's test is for equine infectious anemia.

Answer 52

Foal heat diarrhea; foal heat diarrhea is mainly seen at the age of 7-14 days and is usually very mild in nature. Rhodococcus equi will result in diarrhea in foals that are between ages 1-4 months, but this organism also causes respiratory disease. Clostridium perfringens Types A, B, C will usually result in an acute to peracute diarrhea in foals, leaving most of them dead in 48 hours if treatment is not instituted.

Answer 53

ACTH concentration; this is the typically presentation of equine pituitary pars intermedia dysfunction (PPID), sometimes referred to as Cushing's disease. The disease is a progressive disorder of pituitary enlargement (adenoma). The condition usually affects horses greater than 15 years of age and may affect any breed but ponies and Morgan horses have increased incidence. The classic symptom which is highly suggestive of this condition is hirsutism which is the symptom of a long curly hair coat that does not shed properly. Other symptoms include PU, PD, laminitis, lethargy, excessive sweating or lactation, decreased muscle maass, infertility, and susceptibility to infections such as tooth root abscesses. Horses with PPID will have elevated plasma ACTH concentrations. The TRH stimulation test has also been suggested as a test for PPID.

Answer 54

3rd degree burn; involves the epidermis, dermis, and adnexal structures. 1st degree involves the epidermis only. 2nd degree (partial thickness) involves the epidermis and may go down to deep dermis. 4th degree involves the total destruction of the skin, fat, fascia, bone and muscle.

Answer 55

Bronchoscopy; the horse is most likely afflicted with exercise induced pulmonary hemorrhage (EIPH). The pathogenesis of this conditon is not entirely understood, but the condition is most commonly seen in racing horses. Bleeding may not always be evident and clinical signs include labored breathing, loss of speed during a race, and poor performance. Bronchoscopy of the ariway to visualize evidence of hemorrhage is the best diagnostic test in this list of possible answers. Cytologic examination of a BAL for evidence of hemorrhage is also another way to diagnose the condition. A PIVKA test is used in small animals to help diagnose exposure to rodenticides. A buccal mucosal bleeding test will test platelet function. PT evaluates the extrinsic and common pathways of the coagulation cascade.

Answer 56

no definitive antemortem diagnostic test is available; low serum vitamin E levels are suggestive of EDM; it can only be confirmed through histopathologic examination of the spinal cord and brainstem and the identification of diffuse neuronal fiber degeneration of the white matter. However, many cases of EDM have been associated with low serum vitamin E concentrations; so measurement of vitamin E is suggestive of disease. The exact etiology of EDM is unknown, however, oxidative stress and damage to the CNS is a prominent theory.

Answer 57

Strangles; has been associated with a soft tissue reaction. More recently an intranasal vaccine has become availbale which is associated with local protection without any injection reaction.

Answer 58

Red maple; horses seem to eat the leaves when branches are available, the plant contains an unidentified hemolysin in wilted leaves. Ingestion can be fatal.

Answer 59

culture the discharge for bacteria; the most likely diagnosis for this horse is equine strangles. Strangles most commonly affects younger horses (<5 yeaars), but can cause disease in any age horse. The etiologic agent of this disease is Streptococcus equi subsp. equi. Currently, the diagnostic test of choice to confirm equine strangles is bacterial culture, but recently there is a trend towards PCR testing on guttural pouch samples. While waiting for results, the horse should be separated from any other horses as strangles is highly contagious to other horses. Antibiotic therapy is controversial and thought to lengthen the course of disease rather than shorten it when given at this stage; also, it may possibly interefere with the natural immunity acquired from natural infection. Don't forget to report positive caases of S. equi to the state veterinarian.

Answer 60

remove the objects and thoroughly flush the guttural pouches; these objects are chondroids which are hardened pus filled concretions with bacteria. They most commonly occur when horses develop guttural pouch empyema which is an accumulation of purulent exudate in the guttural pouch due to mucosal infection or drainage from the retropharyngeal lymph nodes from Streptococcus equi subsp. equi. The persistence of pus provides refuge for the bacteria and allows for continued bacterial shedding. When exudate persists, it can become increasingly dense, forming solidified concretions that are difficult to extract and serve as a source for continued prolonged shedding of the organism. To reduce shedding and transmission the chondroids should be removed and the guttural pouch should be flushed with Penicillin G. In addition, these horses should be treated with Penicillin G IM for 7 days and isolated for 30 days and then retested with 3 consecutive series of nsopharyngeal swabs and culture.

Answer 61

Cerebellar abiotrophy; the cerebellum is responsible for the coordination and regulation of range, rate and strength of movement along with balance and posture. Clinical signs associated with cerebellar disease include intention tremors, hypermetria, hypometria, and ataxia. In addition, weakness is not observed with cerebellar abiotrophy. Mentation will be normal if the disease is strictly confined to the cerebellum. The key clinical sign not observed in this question is intention tremors. The clinical signs and presentation are definitely compatible with equine degenerative myeloencephalopathy, cervical vertebral myelopathy, and occipito-atlanto-axial malformation (OAAM). CT is needed to rule in or rule out cervical vertebral myelopathy and OAAM. OAAM is relatively rare, but is most requently observed in Arabian foals. These foals may be born dead, or may develop ataxia at several months of age. Histopathologic examination is the only way to definitively diagnose equine degenerative myeloencephalopathy.

Answer 62

supportive care; sacroiliac luxations in horses are generally considered untreatable. The condition will often stabilize with time and supportive care with rest and NSAIDs. Some horses may return to their previous level of activity or competitiveness but most have residual limitation. Reduction is not typically an option. Total hip arthroplasty has been reported in horses but is typically reserved for severely injured horses that do not improve with supportive care.

Answer 63

Equine degenerative myeloencephalopathy; Dandy walker syndrome is a rare conditon seen in Arabian and Thoroughbred foals which results in a midline defect of the cerebellum and cystic dilation of the fourth ventricle. The pathogenesis of cerebellar abiotrophy still remains unknown, although genetic, toxic and infectious causes have all been incriminated. Cervical vertebral stenotic myelopathy is a developmental disease which is not associated with vitamin E deficiency. The disease results in either continuous or intermittent compression of the spinal cord at the cervical region. Equine degenerative myeloencephalopathy is the conditon recently associated with vitamin E deficiency. Clinical signs are usually in the form of a wide-based stance, conscious proprioceptive deficits, ataxia, paresis, and spasticity, which is worse in the hindlimbs.

Answer 64

haemotobia irritans; this fly is commonly known as the horn fly it causes ventral midline dermatitis as described. They are often found around the horns, back and sides of cattle on cooler days and will affect the ventral abdomen on hot sunny days. Horn flies feed on blood and cause great economic losses in cattle. It can also serve as an intermediate host to Stephanofilaria stilesi, a filarial parasite that causes plaque lesions on the ventrum of cattle. Treatment and control of flies is relatively easy with insecticide sprays, dust bags, or insecticide feed additives. Sarcoptes scabei infections and Culicoides hypersensitivity are extrememly pruritic. Dermatophytosis is a good differential, but Haematobia is a better choice since the horses are affected by flies and housed near cattle.

Answer 65

lawsonia intracellularis infection; not as commonly as in pigs, but it can infect horses. Similar to pigs, the infection usually involves weanling age horses and causes thickening of the small intestine and hypoproteinemia. The low protein is commonly observed as ventral edema clinically. Both Clostridium and Salmonella can cause diarrhea at any age but are not as commonly associaated with ventral edema.

Answer 66

defect in voltage-dependent sodium channels; in this disease, a population of sodium channels fail to inactivate and remain open. This, in urn, results in depolarization of the muscle membrane (closer to threshold) and hyperexcitability of the muscle. With futher depolarization, the muscle cell membrane becomes unexcitable and paralysis may occur. The reason for the hyperkalemia is paartially because of the movement of potassium out of the muscle cell as the myocyte repolarizes.

Answer 67

fracture to the basilar bones (basisphenoid/basioccipital); left head tilt, dropping the left ear and deviation of the muzzle to the right are present in the image. These clinical signs are suggestive of cranial nerve VII and VIII injury, which are located in close proximity tot he basilar bones. The most likely fracture resulting in these lesions is fracture of the basilar bones, a common form of traumatic nerve injury in the foal.

Answer 68

after surgery or a wound in an unvaccinated horse; the antitoxin should be used only when needed due to the risk of causing serum sickness or Theiler's disease. The toxoid should be given at 3, 4, and 12 months then anually and 1-2 months prior to foaling. It should also be repeated after wounds or surgery in a vaccinated horse. The antitoxin should be reserved for horses that are unvaccinated and receive surgery or a wound. It should also be given to foals from an unvaccinated dam soon after birth. It can also be given in a horse showing signs of tetanus.

Answer 69

Antihistamines; in general antihistamines are ineffective at reducing clinical signs associated with cutaneous hypersensitivity diseases in horses. The most important aspect of therapy is reduction of insect exposure. This can be achieved by moving horses away from breeding habitats, frequent bathing, and application of insect repellents. Corticosteroid therapy is required for management of many horses. Short acting corticosteroids should be used first.

Answer 70

most horses improve with treatment but relatively few make a complete recovery; this is a caase of EPM. The 3 A's: asymmetry, ataxia and atrophy are the key findings. The onset of clinical signs are frequently gradual but rapid progression is seen in some cases. The prognosis for horses with EPM is often described as variable. Studies show that about 70% of treated horses will improve but only up to 25% recover completely and perform normally. In addition, a subset (5-20%) of horses may improve while undergoing treatment but then relapse when treatment is discontinued. It is unclear whether relapse represents reemergence or persistence of resistant paarasite or re-exposure.

Answer 71

Ethmoid hematoma; this is a progressive and locally destructive mass that resembles a tumor but is not truly neoplastic. The most common clinical sign is mild, persistent, spontaneous, intermittent epistaxis that can be unilateral or bilateral. Warfarin is not as likely in this horse due to the recurrent nature of the condition and the fact that it is unilateral. Exercise-induced pulmonary hemorrhage actually causes epistaxis only about 10% of the time. Also, since the bleeding is pulmonary in origin, the epistaxis would likely be bilateral. Epistaxis with this condition also occurs immediately after exercise, which was not reported in this horse. Purpura hemorrhagica is a vasculitis that results from a type III immune complex hypersensitivity after a streptococcus equi infection. This leads to vasculitis and the main clinical sign are petechia and ecchymoses of mucous membranes.

Answer 72

Right side - peripheral vestibular dysfunction; peripheral vestibular dysfunction causes signs of head tilt, nystagmus, circling and asymmetric ataxia with preservation of strength. The head tilt towaard the affected side as in circling towards the lesion. Comparatively, central vestibular disease has similar clinical signs but general conscious proprioceptive deficits, weakness and cranial nerve deficits may also be present along with depression.

Answer 73

Tenectomy of the lateral digital extensor; stringhalt is a myoclonic disease affecting one or both pelvic limbs. It causes spasmodic hyperflexion of the leg. The etiology is unknown but sweet pea poisoning is thought to be associated with the condition. Diagnosis is based on clinical signs, but electromyography can be used to confirm the diagnosis. Treatment invovles tenectomy of the lateral digital extensor; however, not all cases respond to treatment.

Answer 74

Cantharidin; aka blister beetle toxicity results in endotoxic shock and renal failure. Horses affected may be found dead, colicking or in cardiovascular shock. Vesicles may form in the mouth and tongue, and if the animal lives long enough, you can expect to see watery feces. Renal tubular damage will be profound, and you will probably observe cardiac arrhythmias. The blister beetle may become processed with hay or pellets; the horses then eat the toxic part of the beetle by accident. Anabaena, Aphanizomenon and Microcystis are all blue-green algae that cause hepatotoxicity.

Answer 75

metabolic acidemia with respiratory compensation; the pH is low which suggests acidemia, the HCO3 is low which suggests the cause of acidemia; the PCO2 is low and respiratory rate is high which suggests respiratory compensation.

Answer 76

this is a second-degree atrioventricular block, which is commonly seen in athletic horses; first-degree and second-degree blocks are considered variations of normal in the horse aand are usually associated with high vagal tone. They are not predisposed to electrical-mechanical disassociation. An electrical rhythm is an ineffective method in trying to determine if there is a ventricular septal defect. If such a defect is suspected, the best way to evaluate the horse is by performing a cardiac ultrasound.

Answer 77

deep digital flexor tendon contracture; there are multiple causes for flexural deformity of the distal interphalangeal joint (deep digital flexure contracture) included rapid bone growth, excessive feeding, faulty nutrition and lack of exercise. The distal check ligament controls the stretch in the long tendon of the deep digital flexor. If this becomes functionally too short, flexion of the interphalangeal joint occurs, resulting in a club foot. If medical therapy is not successful, surgical correction is recommended.

Answer 78

surgical exploration and drain placement; a hygroma is a fluid filled swelling at the carpus, usually seen from repeated trauma leading to local bursitis. Horses are usually not lame from this condition, but have restricted range of motion of the joint. Simply aspirating the fluid and/or injecting corticosteroids is rarely effective and the swelling usually recurs. Surgicial excision of the bursal lining may be indicated when recurrence is a problem.

Answer 79

auriculopalpebral nerve block; blocking this branch of cranial nerve VII (facial nerve) disrupts the motor innervation to the orbicularis oculi, which is the muscle that closes the eye. In the horse, this muscle is very strong and can prevent a thorough ocular exam. To perform this block, lidocaine is injected subcutaneously at the caudal aspect of the zygomatic arch where the nerve is palpable. Because this is a motor nerve, the eye will not be able to close as well, but there is no anesthesia of the tissue.

Answer 80

Dermatophilosis; dermatophilus congolensis is a gram positive, non-acid fast, facultative anaerobic actinomycete. It causes a crusting dermatitis in large animals when there is high moisture on the skin as well as mechanical irritation. Horses with long, wet haircoats are often affected. Lesions are commonly on the dorsum and pasterns of horses and are classically described as paintbrush lesions. It can be diagnosed with a direct smear preparation. Treatment includes keeping the haircoat clean and dry and penicillins if the lesions are severe. Lesions typically heal rapidly.

Answer 81

Strongylus vulgaris; migration of the larvae of strongylus vulgaris and the corresponding immune response can result in thrombosis of the cranial or anterior mesenteric arteries leading to colic and infarction of the bowel. Parascaris equorum causes colic in foals by causing intestinal impaction. Strongyloides westeri is a cause of foal heat diarrhea and can migrate through the lung causing damage. Dictyocaulus is a lungworm. Draschia megastoma is another migrating parasite that can caause focal granulomas in the lung.

Answer 82

A stallion with previous infection with Taylorella equigenitalis; this organism is thought to be eradicated in the US, but is the causative agent of contagious equine metritis, which can lead to infertility (there is usually no clinically apparent disease in the stallion). It is okay to breed a stallion with a history of coital exanthema (Equine Herpesvirus-3) as long as all lesions are cleared. A 180 degree rotation of the testicle is common and of no clinical significance as is a positive bacterial culture from a pre-ejaculate swab; however, heavy growth of Pseudomonas or Klebsiella may make you think twice, as they can be associated with causing endometritis in mares.

Answer 83

Nigropallidal encephalomalacia; consumption of the yellow star thistle destroys the globus pallidus and the substantia nigra. These lesions will result in a characteristic dysphagia.

Answer 84

ethmoid hematoma; these lesions are angiomatous masses that originate from the mucosal lining of the ethmoid conchae or walls of the maxillary or frontal sinus. Guttural pouch mycosis also can result in epistaxis, but the blood originates from the lungs. In the radiograph provided, notice the smooth, well-defined soft tissue mass in the sinus region of this horse. No osseous changes or fluid lines are apparant. In this particular case (ethmoid hematoma), the soft tissue mass is actually dorsal to the ethmoid turbinates (ethmoids are normal appearance in this case). Upon surgical removal, a definitive diagnosis of ethmoid hematoma was confirmed.

Answer 85

pulmonary abscess; the two horizontal lines represent fluid or pus capped by gas within cavitary lesions. In foals, this occurs most frequently with Rhodococcus equi pneumonia.

Answer 86

purulent inflammation and gram negative rods with large capsules; the causative agent of strangles is streptococcus equi ssp. equi, a gram positive cocci with a large capsule. It causes enlargement and suppurative abscessation of the mandibular and retropharyngeal lymph nodes.

Answer 87

60ml/kg/day

Answer 88

65L; the deficit is 35L (deficit x BW ) --> 0.07 x 500 = 35L maintenance is 60ml/kg/day = 30,000ml/day =30L 30L + 35L = 65L

Answer 89

This conduction finding is common in racehorses and is unlikely to contribute to poor performance; second-degree atrioventricular block is commonly seen in athletic horses. First-degree and second-degree blocks are considered variations of normal in the horse and are usually associated with high vagal tone. Horses with second-degree atrioventricular block are NOT predisposed to electrical-mechanical disassociation. This is not a cause of poor perfromance or a concern in horses because high vagal tone is overcome by sympathetic tone during exercise.

Answer 90

Neutrophil; anaplasma phagocytophilum causes equine granulocytic ehrlichiosis. It can survive in host neutrophils and eosinophils and can be seen on a blood smear during the acute phase of disease. This in contrast to Neorickettsia risticii, the causative agent of Potomac Horse Fever, which survives in monocytes and is rarely found in a blood smear. Clinical signs of Anaplasma phagocytophilum include depression, limb edema, petechiation, icterus, and ataxia and is commonly treated with tetracyclines.