Equine

Question 1

Most common site of forelimb lameness in the horse?

Answer 1

• the foot (hoof)

Question 2

4 clinical examination components for direct examination of the foot

(without nerve blocking)

Answer 2

• hoof testers
• palpating where DDFT and SDFT insertions are
• Palpating Distal Sesamoidean Ligaments
• Feeling for digital pulses

Question 3

2 main infectious causes of equine abortion in the UK

Answer 3

• Placentitis (bacterial or fungal) - bacterial occuring at about 3 months (E. Coli or S. zooepidemicus) and fungal at about 6 months (Aspergillus spp.)
• EHV-1 or EHV-2

Question 4

Acute vs. chronic placentitis

(placenta examination)

Answer 4

Question 5

leptospirosis in equine abortion

(how is it different to other infectious causes of placentitis?)

Answer 5

placentitis is diffuse, rather than ascending - wouldn’t see the same gross changes at cervical star as you would for others

Question 6

3 main roots of spread for EHV-1 infections

Answer 6

• Exhaled virus from respiratory infections
• contact with infected fetuses, membranes or fluids
• reactivation of infection in healthy carrier animals - latently infected horse that reactivates the infection

Question 7

What is an important viral cause of equine abortion to keep. in mind for contnental europe and some other countries? (not UK currently)

Answer 7

• EVA (equine viral arteritis)

Question 8

Diagnosis of EVA abortion

Answer 8

• important: the virus does not always cross the placenta. so you may struggle to be able to diagnose off examination of the placenta and aborted fetus
• Virus may have infected the myometrium, the muscular coats of the endometrium causing placental separation
• important to do virus neutralizing antibody

Question 9

A 1.5-year old Quarter Horse gelding is presented to you for symmetric ataxia, weakness, and spasticity of all limbs, but worse in the hind limbs. When walking, the horse frequently drags his toes and the hind limbs frequently interfere with one another. Based on the signalment, history and physical examination findings, which of the following is the most likely cause of these clinical signs?

Answer 9

Equine Degenerative Myeloencephalopathy (EDM)

• The horse in this question has clinical signs most consistent with EDM; cervical vertebral malformation (wobblers) is also a possibility, but was not provided as an answer.

Question 10

Botulism

Answer 10

• Botulism is a disease that occurs when toxins produced by the bacterium, Clostridium botulinum, enter the horse’s body causing weakness which may progress to paralysis
• Botulism is a rapidly fatal disease with motor paralysis
• Botulism is associated with generalized muscle weakness
• This organism grows rapidly in decomposing animal tissue and sometimes in plant material. It results in rapid death due to the paralysis of vital organs. Botulism is not usually an infection but a poisoning. The frequency of botulism in animals is not known with accuracy, but it is low in horses
• There are 7 types of Clostridium botulinum toxins; the C1 toxin is seen in most animal species, although type B is most common in North America and Europe

Question 11

Cauda Equina Syndrome

Answer 11

• Cauda equina syndrome causes analgesia of the perineum.
• Trauma to the sacral/coccygeal area is the most common cause of the syndrome and can result from falls, reversing under obstructions (such as backing under a closed top door to a stall), and tail pulling such as occurs when using the tail to help pick up a down horse

Question 12

Equine Motor Neuron Disease

(EMND)

What is the clincal picture?

Answer 12

• Equine motor neurone disease (EMND) is a condition in which the sporadic degeneration of muscle nerves in mature horses leads ultimately to excessive muscle weakness and wastage.
• It is characterised as a generalised weight loss (due to muscle wastage, or atrophy) despite a normal or even increased appetite
• EMND is typically associated with muscle tremors, shifting of weight while standing, muscle atrophy and recumbency

Question 13

Equine Protozoal Myeloencephalitis

(EPM)

Answer 13

• EPM can cause a range of clinical signs, but is typically with asymmetric neurologic deficits
• Equine protozoal myeloencephalitis (EPM) is a common neurologic disease of horses in the Americas; it has been reported in most of the contiguous 48 states of the USA, southern Canada, Mexico, and several countries in Central and South America. In other countries, EPM is seen sporadically in horses that previously have spent time in the Americas
• Most cases of EPM are caused by an Apicomplexan protozoan, Sarcocystis neurona. Horses are infected by ingestion of S neurona sporocysts in contaminated feed or water

Question 14

Equine Degenerative Myeloencephalopathy

(EDM)

what is the other name for it?

Answer 14

• Equine neuroaxonal dystrophy/equine degenerative myeloencephalopathy (eNAD/EDM) is an inherited neurodegenerative disease characterized by the development of ataxia
• The cause of EDM is unknown, but this disease typically affects young horses (< 2-3 years of age; but older horses can develop disease).
• Clinical signs are a 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 that oxidative damage may play a role in the development of disease.

Question 16

• Describe Pituitary Pars Intermedia Dysfunction in Horses (PPID)
• What clinical signs may be an idication?

Answer 16

• This disorder used to be called equine Cushing’s. - by far the most common endocrine disease in horses
• This condition is a result of hypertrophy, hyperplasia, and micro- or macroadenoma of the pituitary pars intermedia that secretes increased amounts of propiomelanocortin peptides.
• decreased dopaminergic innervation of pars intermedia results in hypertrophy or hyperplasia of pars intermedia
• Adjacent pituitary tissues are compressed and secrete less of some other peptides. Data suggest that horses with this disease have hypothalamic dysfunction and decreased amounts of dopamine
• may see: lack of shedding (during normal spring season), decrease in E, horse in hirsute (more hairy), loss of muscle mass, and may be chronically laminitic

Question 17

Entropion in foals

Answer 17

• Entropion in foals is fairly common and will usually resolve spontaneously - likely will not need surgical treatment
• Surgical correction is reserved for cases that do not resolve, because over correction in a young animal could result in further eyelid defects as the foal grows.
• If clinical signs are severe enough, a procedure where local anesthetic is infused and the eyelid is everted and stapled can be performed as a temporary fix until the problem resolves

Question 18

What vaccine is administered intramuscularly is most likely to cause a local reaction at the injection site of a horse?

Answer 18

• Strangles vaccine
• Historically, an intramuscularly administered Strangles vaccine has been available and has been associated with soft tissue reaction.
• More recently, an intranasal vaccine has become available, which is associated with local protection without any injection reaction
• Not many horses are vaccinated for it in the UK, Isolation is best if there is an outbreak present
• An intranasal product has been shown to stimulate a high level of immunity against experimental challenge. The inductive sites are the pharyngeal and lingual tonsils. Vaccinal organisms must reach these sites in sufficient numbers to trigger protective responses; therefore, accurate vaccine delivery is critical to vaccine efficacy.
• In a small percentage of cases, residual vaccinal organism virulence may result in formation of slowly developing mandibular or retropharyngeal abscesses

Question 19

A pregnant mare was brought out to your barn for observation in anticipation of parturition. After several hours of restless behavior, several gallons of allantoic fluid rush out from the vulva. Which of the following would you expect to happen next for a normal parturition?

Answer 19

• The thin, white, glistening amniotic membrane emerges from the vulva
• This case description is consistent with stage I of labor in the horse leading to stage II

Question 20

Describe Stage I of Foaling

Stage II?

Stage III?

Answer 20

• The first stage of foaling typically lasts 30 minutes to 4 hours. - During this stage, mares act restless and may exhibit signs similar to colic such as flank watching, pawing, and constantly getting up and down.
• When the placenta ruptures (“water breaks”), there may be several gallons of allantoic fluid that come out.
• Usually, within about 5 minutes, the second stage of labor begins and the foals feet and nose appear at the vulva, covered in the white, thin, glistening amnion.
• Stage III - after the foal is born, within 30 minutes to 3 hours after foaling, the placenta should be expelled

Question 21

What does it mean if a red, velvety membrane is seen during stage II of foaling?

Answer 21

If a red, velvety, membrane is seen, this is the chorioallantois which indicates premature placental separation which can impair oxygen delivery to the fetus and can result in death of the foal. Usually, the muzzle will emerge from the amnion by the time the foal’s hips pass through the pelvis but if not, the amnion can be gently broken and removed. Usually, the umbilical cord breaks naturally when the mare stands or foal begins to rise.

Question 22

Template Bleeding Time (TBT)

Answer 22

• The TBT is a test that determines the functional ability of platelets to plug a minute wound.
• A buccal mucosal bleeding test is similar to template bleeding time.
• The APTT and PT determine if there are deficiencies in the coagulation factors and do not assess platelet function.
• Antithrombin activity is sometimes measured when disseminated intravascular coagulation (DIC) is a concern, but is not used to evaluate platelet function.

Question 23

Corynebacterium pseudotuberculosis

(PIGEON FEVER)

Answer 23

• In horses, Corynebacterium pseudotuberculosis causes ulcerative lymphangitis (an infection of the lower limbs) and chronic abscesses in the pectoral region and ventral abdomen.
• Corynebacterium pseudotuberculosis is a gram-positive bacteria with worldwide distribution. Corynebacterium pseudotuberculosis is considered an emerging disease in North America; cases have been reported throughout the United States.
• It is a common and economically important infectious diseases of horses and cattle worldwide
• Three forms of PF have been described in horses: external abscesses, internal infection, and ulcerative lymphangitis or limb infection. Ulcerative lymphangitis and internal infection must be treated more aggressively with antimicrobial therapy, while use of antimicrobials for external abscesses is generally unnecessary.
  *

Question 24

Rhodococcus Equi

Answer 24

• Rhodococcus equi is a Gram-positive coccobacillus bacterium.
• The organism is commonly found in dry and dusty soil
• causes pneumonia in 1 to 4 month old foals. Disease does not occur in adult horses unless there is a severe immunodeficiency
• The disease is often confused with Rotavirus, a highly contagious virus that causes diarrhea in foals. R. equi may occasionally also cause disease in other body systems.
• Inflammation of the eye (uveitis), bone infection, inflammation of the joints, diarrhea and abdominal abscess formation are noted infections outside of the lungs
• Currently, we have identified antibiotics that are very good at treating the infection. Erythromycin, clarithromycin and azithromycin are individually paired with rifampin to treat foals

Question 25

Neonatal Isoerythrolysis

Answer 25

• NI is common in multiparous mares and usually affects foals between 24-72 hours of age. NI results in hemolysis, hyperbilirubinemia, and icterus.
• A low packed cell volume would further support NI.
• NI develops because the newborn foal expresses alloantigens on its red blood cells 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 red blood cells.

Question 26

What is the duration of a mare’s estrous cycle?

Answer 26

• The correct answer is 19-26 days. Estrus in a mare can last 2-10 days but, on average, is 6 days long.
• The mare is a polyestrous animal from the beginning of spring through summer. The estrous cycle’s duration lasts 19-26 days

Question 27

What is this disease? What is a major risk factor?

Answer 27

• melanoma
• Grey coat is a predisposing factor
• one the most common tumors in horses (about 10% of all neoplasms), and gray horses are predisposed with a high risk of around 80%.
• They can occur anywhere but appear most frequently in the perineal region and ventral tail, as is evident in this horse. In horses, they are usually darkly pigmented, as opposed to dogs where amelanotic melanomas occur somewhat commonly.
• UV light is not thought to play a significant role in development of these tumors as they tend to occur in the area where the sun does not shine

Question 28

What type of tumors are Quarter Horses more prone to developing?

Answer 28

• sarcoids
• Sarcoids are skin tumours. They are persistent and progressive skin lumps that occur mainly around the head, in the axilla and the groin area, as well as developing in wounds where they can be confused with ‘proud flesh’ (exuberant granulation tissue)
• Sarcoids are locally invasive tumours called fibrosarcoma and although they are locally invasive, they do not spread to other organs. Sarcoids are the most common skin tumour of horses, accounting for 40% of all equine cancers.
• They affect breeds of all ages and both sexes. Most skin lumps in horses that are non-painful and non-itchy are sarcoids, whereas painful lumps are often due to infection and itchy lumps to allergies.
• Sarcoids do not usually self-cure and affected horses often develop multiple sarcoids at once or serially

Question 29

What body systems are most affected in an anaphylactic reaction in a horse?

Answer 29

• LUNGS AND COLON
• These are referred to sometimes as the shock organs in the horse.
• When a horse undergoes an anaphylactic reaction from an allergen or chemical stimulus, the primary signs will be respiratory and lower GI and will include dyspnea or severe respiratory distress and diarrhea.
• Other common signs include anxiety, tachycardia, piloerection (hair erection), and sweating.
• Treatment of anaphylactic shock usually includes injection with some combination of epinephrine, corticosteroids, and an antihistamine

Question 30

A 3-year old gelding is presented for lameness. Physical exam reveals moist, exudative dermatitis of the central and lateral sulci of the frog of his feet and a thick black discharge with a malodorous smell. Which of the following is an appropriate way to treat the disease?

Answer 30

The correct answer is to trim away necrotic hoof material, apply antiseptic products, apply a bandage, and educate the client on proper hygiene.

The horse has thrush, a condition often caused by Fusobacterium necrophorum in horses. The condition is usually caused by unsanitary conditions, poor foot care, and lack of exercise.

Systemic antibiotics and corticosteroids are usually unnecessary.

Question 31

Foal Heat Diarrhoea

Answer 31

• Foal heat diarrhea is mainly seen at the age of 7-14 days and is usually very mild in nature
• Foal heat diarrhea was originally believed, to be caused by changes within the mare’s milk composition during her heat cycle, leading to a transitory diarrhea in the foal

Question 32

Clostridium Perfringens in Foals

Answer 32

• Clostridium perfringens Types A, B, and 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
• Clinical signs of Clostridium enterotoxemia include severe abdominal pain or colic, foul smelling and sometimes bloody diarrhea, dehydration, depression, abdominal distention and/or rapid death

Question 33

Symptoms of Gastric Ulcers in Foals

Answer 33

Although many foals do not have any symptoms of ulcers, they do develop in a minority of foals and include:

• Intermittent colic, often after nursing or eating
• Poor appetite and nursing for only very short periods of time
• Teeth grinding
• Excessive frothy salivation
• Diarrhea
• Weight loss
• Lying on the back
• Poor growth
• Potbellied appearance
• Rough hair coat

Mild gastric ulcers are seen in approximately 50% of foals during the first four months of life. Most ulcers in foals are considered to be related to the stresses of weaning. These ulcers occur in the stomach or just beyond the outlet of the stomach in the duodenum, which is the first few feet of intestine. The majority of ulcers do not produce symptoms and usually disappear as the foal ages.

Question 34

“Kissing Spines”

Answer 34

• Overlapping spinous processes
• Kissing spines are one of the major causes of back problems in horses.
• They do present the clinician with challenges in diagnosis. The most common presenting complaint is related to performance behavior rather than overt lameness.
• kissing spines was made when one or more vertebrae were either touching or overlapping. - generally T10-T18

Question 35

The Equine Spine

how many cervical?

How many thoracic?

How many lumbar?

How many sacral?

How many coccygeal?

Answer 35

Question 36

Red maple (Acer rubrum) poisoning

Answer 36

• Acer rubrum, the red maple, also known as swamp, water or soft maple, is one of the most common and widespread deciduous trees of eastern and central North America
• Clinical Signs of Toxicity include: lethargy, anorexia, dyspnea, coffee-colored urine, and icterus.
• Horses seem to eat the leaves when branches are available, and the plant contains an unidentified hemolysin in wilted leaves. Ingestion can be fatal​

Question 37

A 10-month old Arabian presents for persistent superficial and deep digital flexor tendon contracture. What surgical option does this patient have?

Answer 37

• The correct answer is distal check desmotomy and proximal check desmotomy.
• The distal check desmotomy relieves the deep digital flexor contracture while proximal check desmotomy relieves superficial digital flexor contracture.
• If the contracture is severe, it may recur 2-4 months after surgery.
• At such time, a suspensory desmotomy is an option but subluxation at the proximal interphalangeal joint is a common consequence.

Question 38

Which of the following does not typically cause ventral midline dermatitis in horses?

• Culicoides hypersensitivity
• Onchocerciasis
• Chorioptes equi
• Haematobia irritans

Answer 38

• The correct answer is Chorioptes equi.
• Chorioptes is a mange mite that is usually found around the foot and fetlock. It causes a pruritic dermatitis that can cause the formation of papules, crusts, thickened skin, as well as alopecia. The mites are often found in the feathered hair around the fetlocks of draft horses.
• As with other mites, ivermectin is the treatment of choice or lime sulfur.
• Culicoides, Haematobia irritans (the Horn fly) and onchocerciasis often cause dermatitis at the ventral midline of horses.

Question 39

Equine Recurrent Uveitis

or

“Moon Blindness”

Answer 39

• It is one of the most common diseases of the equine eye, with an estimated prevalence of 2-25% in the United States.
• Equine recurrent uveitis is characterized by inflammation occurring inside the eye, first impacting the uveal tract (termed uveitis). The uveal tract consists of vascular tissues inside the eye essential to proper nourishment and function of the eye.
• The symptoms observed by owners are often subtle and can range from very mild tearing or swelling of the eyelids, to more obvious squinting and noticeable change in appearance (cloudiness) of the eye. One or both eyes can be affected, and though any horse can be diagnosed with ERU, at risk breeds include Appaloosas, European warm bloods, and draft breeds.

Question 40

Chronic Proliferative Synovitis

Answer 40

• Proliferative synovitis is the enlargement of the fibrocartilaginous pad on the dorsoproximal aspect of the joint capsule attachment of the fetlock joint.
• The cause of this inflammation is thought to be from repetitive trauma from exercise. Typically, this condition is found most frequently in racing Thoroughbreds, but it may also develop in Standardbreds and nonracing breeds. Clinical signs include fetlock joint effusion, firm swelling over the dorsoproximal aspect of the fetlock joint, lameness, and decreased range of motion and a positive response to firm flexion of the fetlock.
• Diagnosis can be suspected by palpation. Radiography can be used to identify associated osteolysis at the proximal aspect of the dorsal mid-sagittal ridge of the distal third metacarpal bone on the lateromedial projection. The radiolucency is a result of the damage to the cortical bone from the overlying fibrous mass. Ultrasound examination can also be performed, and the synovial pad is considered abnormal if it is >4 mm thick, has rounded distal margins, or if hyperechoic regions are found within the pad. Treatment is surgical excision via arthroscopy

Question 41

Which of these vaccines administered intramuscularly is most likely to cause a local reaction at the injection site of a horse?

Answer 41

• Strangles
• Historically, an intramuscularly administered Strangles vaccine has been available and has been associated with soft tissue reaction.
• More recently, an intranasal vaccine has become available, which is associated with local protection without any injection reaction

Question 42

In what cell of the horse does Anaplasma phagocytophilum survive in?

Answer 42

• Neutrophil
• Anaplasma phagocytophilum causes equine granulocytic ehrlichiosis.
• It can survive in host neutrophils and eosinophils and is 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.

Question 43

Equine Granulocytic Erlichiosis

Answer 43

• an infectious, noncontagious, seasonal disease, originally seen in the USA in northern California but now recognized in many states where the tick vector occurs; it is also seen in Europe, Africa, and South America
• ANAPLASMOSIS in horses - This disease is caused by the rickettsial agent Anaplasma phagocytophilum, which is found in the bloodstream after infection is transmitted by tick bite
• horses less than 1 year old may have a fever only; horses 1 to 3 years old develop fever, depression, mild limb swelling, and lack of coordination.
• Adults exhibit the characteristic signs of fever, poor appetite, depression, reluctance to move, limb swelling, and jaundice. Fever is highest during the first 1 to 3 days of infection, but may last for 6 to 12 days.

Question 44

HR/RR Horse

Answer 44

• 38-40 bpm
• foals (70-120bpm)
• 8-16 breaths per minute

Question 45

Normal PCV Horses

Answer 45

• A normal PCV for horses can range from 32%-48%.
• Therefore, a PCV below 30% typically indicates that the horse may be anemic.

Question 46

Potomac Horse Fever

What agent?

Diagnosis?

Tx?

Answer 46

• Potomac Horse Fever (PHF) is a seasonal, sporadic, but acute and potentially fatal typhlocolitis of horses caused by infection with an obligate intracellular gram-negative bacteria, Neorickettsia risticii (formerly known as Ehrlichia risticii)
• (disease usually occurs in the summer in the northern states), includes high fever and diarrhea, and the presence of laminitis, profuse watery diarrhea, leukopenia (normally 5.4 to 14.3 thousand per microliter)
• Diagnosis: supportive test - a PCR of blood or feces
• Drug of choice for Tx: Oxytetracycline - may need to treat empirically as the PCR test will take several days to get results, however PHF is very susceptible to Oxytetracycline

Question 47

Infection of foals with Strongyloides westeri can be prevented by which of the following?

Answer 47

• Treatment of post-partum mare with ivermectin
• Larvae of Strongyloides westeri is transmitted to foals in the mare’s milk.
• Adult horses rarely have patent infections except when larvae harbored in their tissues migrate into a mare’s milk after parturition.
• The worms are found in the small intestine and may cause diarrhea in young horses.
• Ivermectin or oxibendazole are effective in treatment of S. westeri.

Question 48

What might be causing this pulmonary abscess (visible on US) in a a 4 month TB colt? (with weight loss, fever, and increased resp rate?)

Answer 48

• Rhodococcus equi
• R. equi is the most likely cause resulting in pulmonary abscess formation that may be noticed on thoracic ultrasound.
• In the ultrasound image, you should note the capsular structure with an anechoic center which represents a fluid-filled abscess.
• R. equi is typically observed in older foals (2-6 months 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.
• Ultrasonography of the chest can provide a quick screening test for foals with R. equi pneumonia.

Question 49

What is the most common cause of cataracts in horses?

Answer 49

• Uveitis
• Equine recurrent uveitis (also referred to as periodic ophthalmia, recurrent iridocyclitis, and moon blindness) is common in horses.
• There are many proposed causes for this condition, but it is thought to usually be from infection (Onchocerca, Leptospira, or Borrelia) or immune-mediated processes.
• Because recurrent bouts of uveitis can lead to serious problems including cataracts, lens luxation, and glaucoma, it should be treated aggressively with topical and systemic anti-inflammatory drugs and topical atropine to prevent synechiae and ciliary spasm.
• Systemic antibiotics are usually not indicated unless the horse is febrile or an infectious cause is identified

Question 50

Tapeworms found in horses (3)

CS’s?

Answer 50

• anoplocephala magna
• paranoplocephala mamillana
• anoplocephala perfoliata
• Clinical signs include unthriftiness, anemia, and colic.
• Infections can be treated with praziquantel.
• Pyrantel salts are only effective against Anoplocephala spp., but not P. mamillana.

Question 51

“Scratches”

Answer 51

• “Scratches” is a condition of chronic seborrheic dermatitis of the palmar/plantar aspect of the pastern.
• The condition is sometimes referred to by several other names including “grease heel”, “dermatitis verrucosa”, “dew poisoning” and “mud fever”.
• It is not specific to the underlying infectious cause but the condition is generally associated with horses kept in wet or muddy environments

Question 52

Purpura hemorrhagica

Answer 52

• Purpura hemorrhagica is a noncontagious, immune-mediated vasculitis of horses that is characterized by subcutaneous edema of the head, ventral abdomen, and limbs and by petechial hemorrhages of the mucous membranes
• Purpura hemorrhagica most often occurs as a rare complication of Streptococcus equi subsp equi infection but can also develop after infection with other bacterial and viral organisms, particularly those that cause formation of purulent or necrotic foci.
• Purpura hemorrhagica has also reportedly occurred after vaccination or drug administration as well as idiopathically.
• Most of the clinical signs of the disease result from deposition of antigen-antibody complexes in the small blood vessels of the skin.
• Treatment includes the use of immunosuppressive drugs as well as removal of the underlying antigenic stimulus

Question 53

What type of Hypersensitivity is Purpura Hemorrhagica?

Answer 53

• It is a type-III hypersensitivity which is when antigen-antibody complexes accumulate, leading to disease
• Regardless of the cause, purpura hemorrhagica results from accumulation of antigen-antibody complexes that deposit on blood vessel walls and activate a strong immune response (vasculitis). T
• he leaky blood vessels lead to hemorrhage and edema

Question 54

Equine Degenerative Myeoencephalopathy

(EDM)

Answer 54

• This neurologic disease has been associated with a deficiency in vitamin E
• 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.
• Equine degenerative myeloencephalopathy is a progressive neurologic disorder of horses and zebras characterized by diffuse degeneration of axons, myelin, and neurons in the spinal cord and, to a lesser degree, the brain stem

Question 55

Right Dorsal Colitis

Answer 55

• Associated with administration of NSAID’s (i.e. Phenylbutazone)
• The dose of NSAIDs may be within the normal range or higher than recommended dosages.
• This disease is also usually associated with more chronic administration of NSAIDs (>1 week). Some horses may be more sensitive to NSAIDs, with clinical signs such as inappetence, intermittent colic, and hypoproteinemia commonly observed

Question 56

What is the causative agent of equine protozoal myeloencephalitis (EPM)?

Answer 56

• 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.

Question 57

Bog Spavin

Answer 57

• Bog spavin is excessive fluid in the largest of the hock joints.
• This can result in slight or severe enlargement of the hock.
• One or both hocks may be affected.
• It is more commonly seen in younger horses, although it can occur at any age.
• The increase in fluid can be the result of injury (trauma), degeneration of bone or cartilage in the joint (OCD), or joint infection (septic arthritis).
• There may be associated lameness that can range in degree from mild to severe depending on the cause
• No treatment is generally needed for cases without other clinical complications
• Some practitioners recommend draining the fluid but the swelling typically recurs and repeated drainage is not recommended

Question 58

A pony owner has had several ponies develop acute and severe cases of laminitis this season. You evaluate the environment and attempt to determine the cause. Which of the following changes could you recommend to decrease the incidence of this problem?

Answer 58

• Acute laminitis is commonly associated with excess carbohydrate intake.
• Grazing of lush pastures is an especially common precipitating cause in ponies

Question 59

3 main pathways by which laminitis can occur

Answer 59

Question 60

Equine Metabolic Syndrome

Answer 60

• EQUINE metabolic syndrome (EMS) has been defined as the presentation of a phenotype of obesity, insulin resistance and laminitis or a predisposition to laminitis in equids

Question 61

What are the 4 basic blocks used?

in what order?

which is best for alleviating the pain of laminitis?

Answer 61

• The four basic blocks used by equine clinicians are the palmar digital, abaxial sesamoid, low four point and high four point block, each desensitizing more of the limb as your blocks move more proximal on the limb
• The abaxial sesamoid block is best for alleviating laminitis symptoms
• The palmar digital desensitizes the palmar third of the foot whereas the abaxial sesamoid desensitizes the entire foot.
• As laminitis is associated with separation of the dorsal lamina, the abaxial sesamoid block would be most likely help with laminitis.
• desensitizing the foot during acute laminitis is not typically employed as a standard treatment but is rather used to help alleviate pain so that the clinician can perform radiographs of the feet or trim the feet.
• The low 4 point block desensitizes the palmar aspect distal to the distal end of the second and fourth metacarpals.
• The high 4 point block desensitizes the leg distal to the carpus or tarsus

Question 62

What cytologic finding of bronchoalveolar lavage (BAL) fluid would be supportive of RAO (recurrent airway obstruction)?

Answer 62

• neutrophilic inflammation
• However, in RAO, neutrophils are the predominant cellular finding.
• RAO typically affects older horses and is a response to environmental allergens.
• The classic case is the horse that is stalled in the winter and possibly housed in the vicinity of the hay storage.
• When the horse is exposed to hay allergens (via inhalation), bronchoconstriction and neutrophilic inflammation occur resulting in clinical signs

Question 63

Answer 63

• Ventricular Septal Defect
• Clinically, you will hear a murmur bilaterally with the point of maximum intensity on the right side

Question 64

Tetralogy of Fallot

Answer 64

• tetralogy of Fallot consists of an overriding aorta, ventricular septal defect, pulmonic stenosis, and right ventricular hypertrophy
• This congenital anomaly is rather rare
• When listening to a tetralogy of Fallot, one can expect a loud holosystolic murmur on the left 4th-6th intercostal space

Question 65

What do you expect to hear with patent ductus arteriosis (PDA)?

Answer 65

• A patent ductsus arteriosus will create a characteristic continuous machinery or washing machine murmur.
• This will be audible throughout systole and diastole.
• Additionally, the point of maximum intensity is usually on the left side between the 3rd and 4th intercostal space.

Question 66

Suspensory Desmitis

(Intraosseous Desmitis)

Answer 66

• Injuries of the suspensory ligament (interosseous muscle) are common in forelimbs and hindlimbs of horses.
• Lesions are typically classified as affecting the proximal, body, or branches of the suspensory ligament.
• Splints or intraosseous desmitis is inflammation of the intraosseous ligament between the 3rd metacarpal (or metatarsal) bone with the small metacarpal (or metatarsal) bones.
• Periostitis occurs with new bone formation along the splint bones or small metacarpals (or metatarsals) usually due to repetitive concussion, excessive training, poor conformation, or improper shoeing.
• Radiographs are necessary to distinguish this condition from fractures of the splint bones
• Tx: Rest and NSAIDs - phenylbutazone, Flunixin, Firocoxib

Question 67

What feedstuff additive of cattle feed is known to be very toxic to horses and result in cardiomyopathy if consumed at high enough doses?

Answer 67

Monensin

• Monensin is a commonly used coccidiostat in feedstuff of cattle. This ionophore is highly toxic to horses (the toxic dose for hoses is 10 to 15 times less than for cattle) and will result in cardiomyopathy and myocardial necrosis.
• Unfortunately, there is no quick and easy antidote, and treatment usually consists of trying to empty the intestinal tract by using mineral oil, activated charcoal, and fluid therapy.
• Lasalocid and salinomycin are also ionophores that you might worry about, but monensin is much more toxic to horses
• One way of determining prognosis is to evaluate the horse’s fractional shortening via echocardiography. Normally the fractional shortening is 30-40%; if you calculate fractional shortening to less than 20%, the prognosis is poor

Question 68

Pigment Nephropathy

Answer 68

• Pigment nephropathy occurs as a result of myositis (tying up)
• Nephrosis and subsequent renal failure is caused by large amounts of myoglobin being filtered by the kidney.
• This usually occurs in horses that have been subjected to extreme conditions such that the animal breaks down a substantial amount of muscle.
• The same condition can occur with intravascular hemolysis. In this case, the hemoglobin pigment is the culprit

Question 69

“Tying Up”

+

classifications? (2)

Answer 69

• Tying up in horses is commonly used to describe horses that are stiff and reluctant to move due to pain originating from the muscle groups within the back, pelvis and hind limbs, it may also be accompanied by excessive sweating, increased heart rate and respiratory rate

can be classed as:

• RER- Recurrent Exertional Rhabdomyolysis
  
  • RER is often seen in Thoroughbreds, Standardbreds and Arabians
  • It is most likely due to the inability to regulate electrolyte levels in skeletal muscle, affecting muscle contraction
• PSSM - Polysaccharide Storage Myopathy (PSSM)
  
  • Most commonly found in Quarter horse-related breeds, draft horses and Warmbloods
  • PSSM is a heritable trait which results in insulin sensitivity and the abnormal accumulation of glycogen within skeletal muscle

Question 70

Carpus Valgus

Answer 70

• This is one of the most common angular limb deformities that occurs in foals, usually as the result of asynchronous growth of the metaphyseal and epiphyseal growth plates.

Question 71

“Seedy Toe”

Answer 71

• Seedy toe is a separation of the horse’s hoof wall from the underlying sensitive laminae at the white line, resulting in a cavity that fills with crumbling dirt, horn and debris and is prone to associated infection
• also sometimes referred to as “hollow wall” or “dystrophia ungulae”. 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.
• Lameness may be present if there is abscessation or concurrent laminitis.
• To treat seedy toe, any necrotic or infected horn should be removed to establish drainage.
• The area should be cleaned and antiseptics may be applied to cleaned, raw tissues.
• Appropriate supportive shoeing may be necessary until the hoof regrows. The prognosis is generally good if the condition is diagnosed and treated early and no laminitis or deeper tissue involvement is present.

Question 72

A 1.5 year old Hanoverian gelding presents for colic. He was dewormed yesterday with piperazine, and now he is behaving colicky. He also had a previous history of intermittent diarrhea. What is likely to have occurred that resulted in colic?

Answer 72

• Large die-off of ascarids resulting in impaction
• Treatment with piperazine will result in rapid death of ascarids. If a horse has a large burden of worms, this may be contraindicated as they may die rapidly and result in obstruction, as most likely occurred in this case.

Question 73

What are the blue aggregates shown on this neutrophil?

what does it indicate?

Answer 73

• Dohle Bodies indicating toxic change to the neutrophil
• Dohle bodies are bluish-gray inclusions within the neutrophil that are retained aggregates of rough endoplasmic reticulum.
• Dohle bodies are one manifestation of toxic (i.e. endotoxemia) morphologic change to the leukocytes
• Other changes in neutrophil morphology that occur with toxemia include cytoplasmic basophilia, vacuolation, and toxic granulation.
• These changes are commonly found in septic foals and may be considered “defects” in the neutrophil during intense cell production and maturation

Question 74

What markers are we looking for with suspected FPT

(failure of Passive Transfer)

Answer 74

• ELISA Snap test is quickest and gives you a semi-quantitative result

Question 75

What markers indicate Systemic Inflammatory Response Syndrome (SIRS)

(5)

When do we see this often with equine medicine?

Answer 75

• Tachycardia
• Tachypnea
• Hypo- or hyperthermia
• Leukocytosis or leukopenia
• Presence of immature (band) neutrophils

Can see this often with Foal Septicemia (can be a result of FPT)

• common in foals
• predisposing factors:
  
  • FPT - most common
  • contaminated env’t - highly virulent diseases
  • endemic infectious diseases (i.e. salmonella)
  • overcrowding

Question 76

Most common microorganisms isolated from foals with septicemia

• gram negative? (6)
• Gram postive? (3)

Answer 76

• E.Coli = most common gram (-) bacteria isolated from foals with septicemia

Question 77

Clinical manifestations in foals with Septicemia

(6)

Answer 77

• D+ may be secondary to the endotoxin circulating in the bloodstream

Question 78

Treatment of Septicemia in Foals

Answer 78

• Supportive Care
  
  • Fluid Therapy
  • Plasma
• Antimicrobials
  
  • ​Beta-lactam + aminoglycoside (common combo used)
    
    • beta-lactam often penicillin
• Nutritional Support

Prognosis is varibale: depends on bacteria virulence, duration, financial restraints, complications (septic arthritis, umbilicus infection)

Question 79

3 main signs of Potomac Horse Fever (PHV)

Answer 79

• High Fever
• Severe D+
• Presence of laminitis

often acute in presentation and during the SUMMER MONTHS

may see concurrent dehydration and leukopenia

Tx of choice: Oxytetracycline

Question 80

African Horse Sickness

What is it and what is it transmitted by?

Answer 80

• African horse sickness (AHS) is a viral disease of equids that is transmitted by insects, primarily Culicoides.
• African horse sickness is endemic in sub-Saharan Africa and outbreaks have periodically extended to the Middle East and southern Spain.
• The primary and biological vector is Culicoides but the virus may also be transmitted by mosquitoes. The virus has been isolated from certain ticks but arthropod transmission is not believed to play a significant role.

Question 81

Clinical Signs of African Horse Sickness

Answer 81

• Clinical signs of AHS typically develop 5-7 days after infection and begin with fever and conjunctivitis. Some animals may recover but many go on to develop the pulmonary and/or cardiac forms of AHS.
• The pulmonary form consists of acute respiratory distress, coughing, sweating, and foaming from the nostrils; this form is usually fatal.
• The cardiac form consists of edema of the head and neck as well as abdominal pain and depression.
• A characteristic sign is swelling in the indentation above the eyes (also referred to as swelling of the supraorbital fossa). About 50% of animals with the cardiac form die from heart failure while the rest gradually recover after about one week

Question 82

St. John’s Wort

Answer 82

• St. John’s wort acts as a primary photosensitizer and can lead to photophobia, conjunctivitis, sloughed skin, and icterus
• can leave horse with skin sloughing due to cutaneous photosensitization
• toxicity which occurs as a result of the equine consuming the weed which contains hypericin, a chemical known to cause photosensitization in horses, sheep, cattle and goats

Question 83

Strongyloides Westeri

Answer 83

• Strongyloides pass from the host in the larvated form and are recognizable as an oval-shaped, thin-shelled embryonated egg
• Larvae of Strongyloides westeri are transmitted to foals in the mare’s milk.
• Adult horses rarely have patent infections except when larvae harbored in their tissues migrate into a mare’s milk after parturition.
• The worms are found in the small intestine and may cause diarrhea in young horses.
• Ivermectin or oxibendazole are effective in treatment of S. westeri.

Question 84

Strangulating Lipoma

Answer 84

• A lipoma is a fatty tumor that forms in a horse’s abdominal cavity. The tumor forms on the mesentery, a thin sheet of tissue that encloses the intestines
• Lipomas are a common cause of small intestinal obstruction in older horses.
• Typically, a section of the small intestine becomes intertwined with a pedunculated lipoma, resulting in obstruction and possible devitalization of the small intestine.
• Surgical correction is necessary to correct this problem.

Question 85

Onchoceriasis

Answer 85

• caused by Onchcerca cervicalis
  
  • Microfilariae in dermis.
  • Ingested by biting flies(Culicoides spp).
  • Develop to infective stage.
  • Deposited by fly on to skin during feeding.
  • Adult worms found in tendons/ligaments, typically nuchal ligament.
• When a horse is bitten by a gnat carrying onchocerca larvae, the larvae migrate through the bloodstream where they mature and release very small larvae known as microfilaria which then migrate to the skin resulting in an inflammatory reaction known as ventral midline dermatitis.
• When the lumps become abraded by the horse rubbing against a fence post or other surface causing sores. gnats and other biting insects feed on the sores and carry the microfilariea infestation to other horses.
• Culicoides midges act as intermediate hosts and transmit the microfilaria to sites such as eyes, eyelids, forehead and ventral midline.
• Ivermectin or moxidectin generally bring about marked improvement within 2 to 3 weeks

Question 86

Anthrax

Answer 86

• Anthrax is caused by infection with bacteria known as Bacillus anthracis.
• These bacteria form spores, which are extremely resistant to environmental conditions such as heating, freezing, chemical disinfection, or dehydration that typically destroy other types of bacteria.
• Thus, the spores can persist for a long time within or on a contaminated environment or object. Horses may consume the spores while grazing in areas where anthrax has been a problem
• After exposure, the typical incubation period is from 3 to 7 days.
• Once the bacteria infect an animal or human, the organisms multiply and spread throughout the body. They produce a potent and lethal poison (toxin) that causes cell death and breakdown of the infected tissues.
• This results in inflammation and organ damage, eventually leading to organ failure. The bacteria spread throughout the body through the blood and lymphatic (immune) system.
• Human cases of anthrax may follow contact with contaminated animals or animal products. People should use strict precautions (wearing gloves, protective clothing, goggles, and masks) when handling potentially infected animals or their remains

Question 87

What is the achilles tendon composed of in a horse?

Answer 87

The equine Achilles tendon is composed of the:

• gastrocnemius tendon (GT)
• the tarsal tendon of the biceps femoris
• semitendinosus and gracilis muscles
• superficial digital flexor tendon (SDFT)
• tendon of the soleus muscle

Question 88

Conjunctival Pedicle Graft

Answer 88

• The conjunctiva is the pale pink tissue that covers the ‘white’ of the eye. It is a thin, strong tissue containing many blood vessels. These properties make it a useful graft material for corneal ulcers.
• Conjunctival pedicle grafting is performed with the aid of an operating microscope. A strip of conjunctiva is freed and rotated so that it covers the ulcer, then stitched into position using very fine dissolvable suture material.
• The conjunctival graft provides a blood supply and physical support to the ulcer to allow it to heal. The main disadvantage is that it reduces vision, at least temporarily. The graft usually thins over in the months following surgery and in many cases can be left in place long-term. However, if the graft is large or is affecting vision then it can be surgically removed under a brief anaesthetic

Question 89

A-cell graft

Answer 89

Question 90

Corneoconjunctival transposition (CCT) graft

Answer 90

A CCT graft is a form of ‘sliding’ graft in which healthy cornea adjacent to the ulcer is moved into the defect to provide structural support for repair. The conjunctiva remains attached to the healthy cornea and slides across with it bringing a blood supply. Initially the graft will be reddened but in time it becomes clearer and can lead to good vision post-operatively.

Question 91

Tendinitis

Answer 91

• Inflammation of a tendon can be acute or chronic, with varying degrees of tendon fibril disruption.
• Tendinitis is most common in horses used at fast work, particularly racehorses.
• The problem is seen in the digital flexor tendons and is more common in the forelimb than in the hindlimb.
• In racehorses, the superficial digital flexor is involved most frequently. The primary lesion is a central rupture of tendon fibers with associated hemorrhage and edema.
• intermittent lameness and bulge at the metacarpals are classic for bowed tendon or tendonitis.

Question 92

Cervical Vertebral Malformation

(CVM)

or

cervical stenotic myelopathy

or

“wobblers”

Answer 92

• CVM causes compression of the cervical spinal cord resulting in associated clinical signs.
• It is most commonly observed in 1- to 2-year old, rapidly growing, male horses -Thoroughbred and Quarter Horses are more commonly affected, although other breeds have been reported.
• A consistent pathologic finding in horses with CVM is narrowing of the vertebral canal
• Typically associated with symmetric ataxia, paresis, and spasticity.

Question 93

What should the saggital ratio be for horses normally?

(in diagnosing CVM)

Answer 93

• The sagittal ratio should be greater than 52% (C4-6) to 56% (C7)
• Myelographic studies are necessary for definitive ante-mortem diagnosis of CVM.

Question 94

Length of Oestrus Cycle in a horse?

Dioestrus?

Answer 94

• 5-7 days
• Ovulation is 1-2 days prior to the end of oestrus
• Dioestrus lasts approx. 14-16 days

Question 95

Possible side effects of PGF2a injection in horses

Answer 95

Question 96

When does “foal heat” most often occur?

Answer 96

• The first ovulation post-partum, “foal heat” ovulation, occurs about 9-10 days after foaling

Question 97

Important Causes of Diarrhoea in Foals

Answer 97

Question 98

Bacterial related Diarrhoea in Foals

+ symptoms usually seen?

Answer 98

most common bacteria cultured from sepsis was enterococcus spp. , but can be other!

Question 99

Treatment for foals with gastric ulcers

Answer 99

Question 100

Lawsonia Intracellularis in foals

Answer 100

• Obligate intracellular organism, gram negative, faecal-oral transmission
• CS’s: D+, WL, Peripheral Oedema, WL
• Diagnostics: Hypoproteinemia, Hypoalbuminemia, Anemia, Leukocytosis
• Diagnosis: CS’s and signalment, thickened intestine via US, PCR of feces, serum Ab titre
• Treatment: AB’s with intracellular penetration!
  
  • tetracycline
  • erythromycin
  • clarithromycin
• Supportive care:
  
  • colloids - due to hypoproteinemia
  • nutritional support

Question 101

In what season is anestrus normal in the horse?

Answer 101

• WINTER
• It is normal for horses to be in anestrus in the winter season.
• They will not respond to teaser stallions and have inactive ovaries and uterus.
• As the length of day increases at the end of the winter, the horses should return to normal cycling. This can be brought on with artificially increasing the length of light exposure.
• At the end of this period, it is normal for mares to have an inconsistent transitional period as they return to breeding. This is referred to as the vernal transition

Question 102

Vernal Transition in Mares

Answer 102

• During anestrus, the uterus is flaccid, and the ovaries are inactive with no significant follicles or corpora lutea. The cervix may be closed but not firm and tight, or it may be thin, short, and dilated.
• As the length of daylight increases, mares undergo a vernal transition and the ovaries become active, with numerous large (>25 mm) follicles. The cervix and uterus have minimal tone.
• Mares have three or four prolonged intervals of estrus (periods of sexual receptivity to the stallion) during the vernal transition, but ovulation does not occur.
• The end of vernal transition is marked by a surge of luteinizing hormone and subsequent ovulation

Question 103

Approximate Seasonal Oestrus of horses?

Cycle length?

Answer 103

• In aneostrus (no follicular development) from October- Spring, generally
• Duration of estrus: 5-7 days
• Ovulation: 1-2 days prior to end of estrus

Question 104

“Choke” in Horses

Answer 104

• Choke is a condition in horses in which the esophagus is blocked, usually by food material. Although the horse is still able to breathe, it is unable to swallow, and may become severely dehydrated
• Choke is one of the “top 10” emergencies received by equine veterinarians
• Xylazine is commonly used to sedate the horse in order to pass a tube and then gently flush the esophagus with water.
• Lidocaine is given to help relieve discomfort and flunixin meglumine is given as a non-steroidal anti-inflammatory.
• If the choke does not resolve on your first try, give the horse 12-24 hours and maybe some IV fluids; then try again if necessary. This usually does the trick as long as you are not dealing with an anatomical choke (esophageal diverticulum) or a very severe case

Question 105

What is the most frequently observed side effect associated with acepromazine use in horses?

Answer 105

• Hypotension
• Life Threatening SE’s: hypotension, anemia, dehydration
• Acepromazine may cause paraphimosis in male horses, but this is not very common. However, because of this, many veterinarians will not use acepromazine on stallions.
• Acepromazine actually has anti-arrhythmogenic properties. Acepromazine does reduce the seizure threshold, but seizures are not as common as hypotension.

Question 106

Average gestation length in the mare is how long?

When would a foal be considered premature?

Answer 106

• The correct answer is 345 days, although gestational length can range from 330-360 days. It is good to have knowledge of previous gestational lengths because individual brood mares have the same/similar gestational lengths every year, allowing accurate estimate of foaling date.
• Additionally, this is important because many horse owners want mares to foal in mid-January for the reason that in racing, all horses have an artificial birthday on January 1st. In order to achieve this, it is recommended to breed in mid-February.
• Since the horse is seasonally polyestrous and would naturally start cycling in April or May, artificial lighting is often used starting in mid-December to promote estrus in mid-February.
• Most foals are considered premature if born prior to 320 days and prolonged gestation is typically associated with greater than 365 days.

Question 107

Tyzzers Disease in Foals

Answer 107

• Tyzzer’s disease is caused by a bacterium named Clostridium piliforme (Bacillus piliformis). –> causes acute necrotizing hepatitis
• acute: fever, icterus, D+
• This organism is an obligate intracellular pathogen and can be grown only in tissue cultures.
• The disease in horses occurs as an acute, typically fatal disease of foals around one month of age - It affects only foals from about 1-6 weeks of age

Question 108

Subsolar Abscesses

Answer 108

• Subsolar abscesses result from a puncture wound in the hoof from a penetrating foreign body or poor farrier work. Lameness is usually severe.
• Clinical signs may include pointing of the affected foot and increased heat and pain, which progresses to the coronary band.
• Edematous swelling of the pastern and fetlock may occur.
• In neglected cases, draining at the coronary band may occur in 2-3 weeks.
• Treatment consists of disinfectants and poultices.
• Ensuring adequate drainage is the mainstay of therapy.
• If a foreign body is present, it should be found and removed, and adequate drainage should be established

Question 109

Left Dorsal Displacement of the Colon in Horses is….

Answer 109

• the same as Nephrosplenic Entrapment
• In this case, the colon becomes trapped in the renosplenic space

Question 110

Theiler’s Disease

Answer 110

• Theiler’s disease, or equine serum hepatitis, is an infrequent but sometimes life-threatening liver disease of adult horses
• Theiler’s disease will cause and acute multifocal to diffuse hepatitis along with necrosis too
• In North America, the majority of recent cases have been associated with the administration of tetanus antitoxin, although commercial plasma products also have been incriminated.
• The number of horses that become ill following administration of a specific lot of incriminated blood product is estimated at 1 to 2%, although more horses might have subclinical disease
• virus has now been associated in cases as well: Theiler’s disease-associated virus (TDAV) is a newly discovered equine flavivirus
  *

Question 111

Structures of the Stay Apparatus

(Hindlimb)

Answer 111

• Patellar locking
• Reciprocal Apparatus: peronius tertius, Superficial DFT, Gastrocnemius
  
  • Damage to the peroneus tertius muscle disrupts the stay apparatus of the hind limb. The characteristic diagnostic feature is the ability to extend the hock and flex the stifle simultaneously because an intact peroneus tertius prevents this.
• Check Apparatus: accessory ligament of the DDFT

Question 112

Navicular Disease

Answer 112

• associated with any of these structures: navicular bone, navicular suspensory or deep digital flexor tendon, navicular bursa, or several other heel areas
• Results in palmar foot pain
• pain of hoof testers, stilted gait, narrow heels
• It most commonly describes an inflammation or degeneration of the navicular bone and its surrounding tissues, usually on the front feet.
• It can lead to significant and even disabling lameness.

Question 113

Horses living in a sandy region such as California and Florida tend to be predisposed to developing sand enteropathies. If one is suspected, which of the following treatments will be most effective?

Answer 113

• Psyllium
• Psyllium is a hemicellulose laxative that has the ability to bind with sand and help remove it from the gastrointestinal tract.
• Feeding the horse in a stall and/or utilizing hay racks will also help the inadvertent consumption of sand that may be ingested if a horse is eating on sandy ground.

Question 114

Combined Immunodeficiency (CID) in Foals

Answer 114

• Arabian foals are susceptible
• Arabian foals can develop combined immunodeficiency (CID) characterized by a lack of production of functional lymphocytes.
• No curative treatment exists, and foals will succumb to infection.
• In a CID foal, the foal typically has immunity from maternal antibodies for the first few months of life.
• However, as maternal antibodies begin to wane after 2-3 months, foals with CID will begin to develop recurrent infections that are responsive to antimicrobials.
• Once antimicrobials are discontinued, infection returns. Owners should be advised on the heritable nature of this disease.
• A genetic blood test is available to determine if a horse is a carrier of the CID trait.

Question 115

hyperkalemic periodic paralysis (HYPP)

Answer 115

• Autosomal Dominant mode of transmission
• Hyperkalemic periodic paralysis (HYPP) is an inherited disease of the muscle which is caused by a genetic mutation.
• In affected horses, a point mutation exists in the sodium channel gene (SCN4A) that can be passed on to offspring.
• HYPP was one of the first genetic disorders to be elucidated in the horse - This trait is a point mutation traced back to a single sire named Impressive that causes a single amino acid substitution and the resulting phenotype
• results in an excessive amount of potassium in the blood (hyperkalemia).
• This causes the muscles to contract more readily than normal.
• Horses with HYPP can experience unpredictable attacks of muscle tremors or paralysis, which in severe cases can lead to collapse and sudden death due to cardiac arrest or respiratory failure

Question 116

The auriculopalpebral nerve is a branch of the…

what does the block affect?

Answer 116

• FACIAL NERVE (VII)
• Therefore the block affects MOTOR ONLY
• The auriculopalpebral block is useful in providing eyelid akinesis by blocking motor innervation primarily to the orbicularis oculi, thereby allowing manipulation of the eyelids without putting pressure on an already painful eye.
• This block is motor only and does not provide any desensitization

Question 117

Suprorbital Nerve Block

Answer 117

• The supraorbital/frontal nerve block can be used to block a branch of the ophthalmic division of the trigeminal nerve, desensitizing the middle two-thirds of the upper eyelid and forehead skin.
• It may also provide some motor block of the levator palpebrae superioris due to a branch of the oculomotor nerve which runs adjacent.

Question 118

Duodenitis-proximal jejunitis (DPJ)

Answer 118

• Duodenitis-proximal jejunitis (DPJ) is an inflammatory process of the proximal part of the small intestine and occurs sporadically in horses. It is clinically characterized by an acute onset of ileus and nasogastric reflux leading to systemic signs of toxemia
• also known as either anterior enteritis, or proximal enteritis ad has the characteristic reflux, fever, peritoneal fluid characteristics, rectal findings, the depression and relatively less pain than would be expected with an obstruction.
• The cause is still uncertain, but a relationship of this disease to positive cultures of reflux for Clostridium difficile has been found.
• Typically these cases are treated medically, which would include repeated decompression of the stomach, IV fluids, replacement of electrolyte deficiencies, analgesics and correction of any acid-base abnormalities.

Question 119

Polysaccharide Storage Myopathy

(PSSM)

Answer 119

• A subset of horses have a storage disorder in which there is an accumulation of glycogen and abnormal polysaccharide within the skeletal muscle.
• seen in up to 50% of draft horses!
• PSSM has been linked to an autosomal dominant mutation of the glycogen synthase gene in Quarter Horses.
• However, other breeds, such as Paint, Appaloosas, Warmbloods and draft horses can also be affected. Horses with PSSM often have elevations in creatine kinase and aspartate aminotransferase; rhabdomyolysis in PSSM likely results from an energy deficiency within the contracting muscles
• may get intermittent signs of: exercise intolerance, weakness, muscle fasiculations and a stiff abnormal hind-limb gait
• Excessively high insulin sensitivity and a build-up of glycogen in the muscle fibers are also characteristic of PSSM. Research suggests that PSSM-affected horses use stored glycogen for energy normally, and therefore the problem may lie in excessive production and storage of glycogen.
• Horses with clinical signs of PSSM have been known to benefit from diets lower in starch and higher in fat than traditional equine rations.
• commonly diagnosed by muscle biopsy or PCR

Question 120

Gasterophilus spp.

Answer 120

BOT FLIES

• Gasterophilus intestinalis, which is the common bot, typically will lay their yellowish eggs on the medial aspect of the forelimb cannon bones
• yellowish eggs are noted on the medial aspect of the cannon bone

Question 121

What drug is useful in correcting an arrhythmia in a horse, such as ventricular tachycardia?

Answer 121

Lidocaine

• Lidocaine has been reported as the drug of choice to control ventricular dysrhythmias in horses (1).
• Lidocaine decreases the conduction of cardiac impulses, abolishes abnormal spontaneous electrical activity originating from diseased heart tissue, and increases the refractory period

Question 122

Mast Cell Tumors in Horses

Answer 122

• prognosis is good!
• They are often benign and excision is usually curative
• They can occur anywhere on the horse, but are often found in the dermis or subcutis of the head or legs. The tumors may also invade underlying musculature, but are often walled off by aggregates of fibrous stroma.

Question 123

Ethmoid Hematoma

Answer 123

• An ethmoid hematoma 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.
• Serosanguinous → mucopurulent nasal discharge - uni- or bilateral - may precede or follow low volume epistaxis; can be intermittent.
• An expanding lesion on the ethmoid turbinate or adjacent paranasal sinuses that causes a low-grade intermittent nasal hemorrhage

Question 124

What parasite is common in foals?

What is the lungworm of adult horses?

Answer 124

• Parascaris equorum
• This is a roundworm that undergoes migration through the lung. It is common in foals, and during its migration, it can damage the lower respiratory tract and carry in bacteria
• Dictyocaulus arnfeldi is the equine lungworm, but it generally does not cause clinical signs in foals; however it can cause cough and respiratory signs in adults.

Question 125

About how much protein does a horse require in their dry matter intake?

Answer 125

• A horse requires about 1.3 g protein per kilogram body weight or about 40 g 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

Question 126

What is the most appropriate treatment for a horse with equine protozoal myeloencephalitis?

Answer 126

• Trimethoprim-sulfa (broad AB) and pyrimethamine (treatment for toxoplasmosis and cystoisosporiasis)
• Equine protozoal myeloencephalitis is caused by Sarcocystis.
• This combination of drugs blocks folate metabolism by the protozoan at multiple steps and is generally agreed to be the most effective treatment for this condition.
• Recently, ponazuril has been approved and labeled for the treatment of EPM in horses and works by the same general mechanism.

Question 127

On which side do horse teeth need to be floated?

(Maxilla/Mandible)

Answer 127

Maxilla buccal and mandible lingual

This is because the mandible is narrower than the maxilla thus predisposing points and hooks to form at the buccal surface of the maxilla and the lingual surface of the mandible. If these become sharp they can irritate tissues, cause difficulty in mastication, lacerate the tongue and cheek, and result in weight loss

Question 128

Ileocolonic agangliosis

Answer 128

“Lethal White Foal Syndrome”

• This is an autosomal recessive trait seen in Overo horses.
• The foals are white with blue irises.
• Diagnosis is confirmed by histopathology showing a lack of ganglia in the colon.
• Most develop colic and die by 2 days of age

Question 129

Kenney Categories for Uterine Biopsies

Answer 129

• Uterine biopsies in horses are most commonly used to determine the amount of fibrosis present in an older mare’s uterus, which indicates her ability to carry a foal to term.
• Biopsies can be categorized into Kenney categories, which is a scoring system from 1-3 where a “1” means there are minimal changes and a “3” indicates marked changes.
• A mare with a score of “3” has approximately a 5% chance of carrying a pregnancy to term. However, she may still be able to get pregnant.
• Biopsy will show some changes that reflect the phase of the cycle, but is not an accurate way to determine a mare’s current phase.

Question 130

Eastern equine encephalitis

(EEE)

Answer 130

• Eastern equine encephalitis (EEE) is an extremely rare but serious and often fatal infection that causes encephalitis or inflammation of the brain. It is spread by the bite of a mosquito infected with EEE virus (EEEV).
• EEEV can also infect a wide range of animals including mammals, birds, reptiles, and amphibians
• likely get progressive neurological signs
• depression –> circling, head pressing —> recumbent
• Horses are normally vaccinated for it!! - check Hx

Question 131

Clostridium difficile

Answer 131

• Clostridium difficile is a spore-forming bacteria commonly associated with enterocolitis and diarrhea in adult horses and foals.
• Transmission of C. difficile occurs via the oral-fecal route
• C. difficile is a Gram-positive, rod shaped, obligate anaerobe
• C. difficile can survive for prolonged periods of time in the spore form
• The 2 main virulence toxins are toxin A and toxin B.
• Risk factors for the development of disease include antibiotic treatment and hospitalization, but does not include administration of NSAID

Question 132

Glanders Disease

Answer 132

• short- or longterm, usually fatal disease of the horse family caused by the bacterium Burkholderia mallei.
• The disease is characterized by the development of ulcerating growths that are most commonly found in the upper respiratory tract, lungs, and skin
• It is thought to be endemic in regions of the Middle East, Asia, Africa, and South America. Glanders can cause disease in donkeys, mules, and small ruminants. Glanders is primarily a concern in horses because they can be chronic or occult carriers that intermittently shed this deadly and potential zoonotic pathogen.
• Burkholderia mallei causes 3 different forms of disease; nasal glanders, pulmonary glanders, and cutaneous glanders (also referred to as Farcy).
• Burkholderia mallei can be identified in smears made from fresh lesions as mainly extracellular straight Gram-negative rods with rounded ends. Several diagnostic tests exist including PCR, ELISA, and Western Blot but the two that you actually need to know about because they are used in international trade are complement fixation (CF) serology and the mallein test.
• The mallein test is considered the most reliable, sensitive, and specific test; it involves injection of mallein purified protein derivative intradermally into the lower eyelid. The test is read at 24 and 48 hours and a positive reaction is characterized by edematous swelling or purulent discharge.
• Horses should not be treated; local authorities should be notified if a case is suspect and if disease is confirmed, horses must be humanely destroyed and affected carcasses should be burned and buried

Question 133

You have diagnosed gastric ulceration in a 3-year old horse via endoscopy and wish to pursue the most effective possible medication for reducing gastric acidity and increasing gastric pH. Which drug most effectively accomplishes this in the horse?

Answer 133

• Omeprazole
• Omeprazole is a proton pump inhibitor, and has been found in comparative trials to be more effective in the equine at reducing gastric acidity and raising gastric pH than the others.

Question 134

Osselets

Answer 134

• Osselets are inflammation of the periosteum on the dorsal distal epiphyseal surface of the third metacarpal bone and fetlock joint.
• As in this case, they are often (but not always) bilateral.
• Osselets typically begin from chronic stress injury to the front fetlock(s) from repeated concussive forces during racing and hard training.
• Horses with long or upright pasterns may be predisposed.
• The major clinical signs are increasing lameness and a short choppy gait.
• Thickening and soreness of the fetlock are also frequently seen.
• Early diagnosis and intervention is important because once the condition progresses to osteoarthritis, the prognosis is much worse.
• If recognized early and treated with rest, anti-inflammatory medications, and intra-articular sodium hyaluronate injections, many horses can recover completely.

Question 135

Low vs. High Ringbone

Answer 135

• Low ringbone is osteoarthritis of the distal interphalangeal (coffin) joint.
• High ringbone is osteoarthritis of the proximal interphalangeal (pastern) joint

Question 136

You perform a physical exam on a horse and note pale mucous membranes. A CBC is submitted for analysis. What would you expect to see on your CBC if this horse has hemolytic anemia that has been going on for 10 days or more?

Answer 136

Normocytic, Normochromic Anemia

• In the horse, it is very uncommon to see morphologic changes to red blood cells, even if there is a strong regenerative response.
• Therefore, most types of anemia in the horse will be normocytic, normochromic.

Question 137

Horses are predisposed to developing enteroliths in California. What food item is considered to be playing a role in the formation of enteroliths?

Answer 137

Alfalfa Hay

• Alfalfa hay in California is thought to be particularly high in magnesium. This may be a predisposing factor which results in magnesium ammonium phosphate enteroliths

Question 138

What is the treatment of choice for a Rhodococcus equi infection in a foal?

Answer 138

• Erythromycin (or other macolide antimicrobial such as clarithromycin or azithromycin) and rifampin
• This is a must-know fact, as this disease is very commonly encountered.
• Treatment is usually for about 2 months but should be based on resolution of clinical signs, radiographic signs, and bloodwork.
• More recently, newer macrolide antimicrobials such as Clarithromycin and Azithromycin have been used in foals with R. equi pneumonia.
• One clinical study demonstrated better outcome with Clarithromycin and rifampin; additionally, Clarithromycin is typically administered twice daily, whereas erythromycin may have to be administered four times a day.

Question 139

What is the treatment of choice for atrial fibrillation in the horse?

Answer 139

• Quinidine Sulfate
• Ideally, you would begin oral dosing of quinidine via a nasogastric tube at 2 hour intervals until there is conversion or toxicosis.
• An increase in the QRS duration of greater than 25% as compared to before initiation of treatment is considered a sign of toxicity.
• Clinical signs of toxicosis include colic, ataxia, hypotension, diarrhea, and edema.
• Digoxin will not convert an atrial fibrillation to a normal rhythm. However, it is indicated as adjunctive therapy when the vagolytic effect of quinidine causes a significant acceleration in ventricular response rate, the resting heart rate in excess of 90 beats per minute, if the horse is exhibiting a low vagal tone, or if conversion has not been achieved within 24 hours of initiating quinidine therapy.

Question 140

Which antibiotic is contraindicated in foals?

Which are commonly used?

Answer 140

• Enrofloxacin is a fluoroquinolone and thus, its mechanism of action involves the inhibition of DNA gyrase. The reason you don’t want to use it in foal is because it can result in arthrotoxicity and subsequent erosion of cartilage.
• Ampicillin, gentamicin, and amikacin are commonly used to provide broad-spectrum coverage against potential septicemia. Ampicillin is a penicillin; gentamicin and amikacin are both aminoglycosides. Cefazolin is a first-generation cephalosporin that is occasionally used in the face of septicemia if a penicillin is not available

Question 141

What is the drug of choice for treatment of Anaplasma phagocytophilum infection?

Answer 141

• Oxytetracycline
• Anaplasmosis (formerly Ehrlichi equi) infects primarily neutrophils and form inclusion bodies which consists of one or more coccobacillary organisms within these cells, known as morula.
• The complete pathogenesis of this disease is not fully elucidated but the organism is spread via tick bites

Question 142

What are 3 general signs you would see with a horse with an unstable joint?

(ex: hock - which is actually pretty stable as a joint!)

Answer 142

• effusion
• lameness
• osteoarthritis

Question 143

Describe Osteochondrosis dessicans in 4 words?

Answer 143

• Failure of Endochondral Ossification

Question 144

Older equine patient comes in for quidding.…

Answer 144

• consider DIASTEMA of the cheek teeth
• Diastema is the word we use to describe a gap between adjacent teeth
• food can get stuck in there and cause periodontal disease and be extremely painful for horses!
• There are various different ways of treating diastema. The first approach is to flush out the gap with a special instrument to remove all the food material.
• We can then place dental impression putty into this gap to allow the gum time to heal and prevent further trapping of food.
• We normally combine this treatment with rasping the opposing tooth to prevent the continued compressing of more food into the gap.

Question 145

9 cartilages of the laryngeal skeleton

Answer 145

• the thyroid cartilage (largest)
• cricoid cartilage
• epiglottis
• arytenoid cartilages (involved with laryngeal hemiplegia in horses)
• corniculate cartilages
• cuneiform cartilages.

The first three are unpaired cartilages, and the latter three are paired cartilages

Question 146

Pre-pubic tendon rupture

Answer 146

• 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.

Question 147

Carpal fractures in horses occur most commonly in which carpal bones?

Answer 147

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 frequently the treatment of choice

Question 148

Repair of a pneumovagina in the mare involves which of the following?

Answer 148

• Placing horizontal sutures at the dorsal aspect of the labia and increase the weight of the mare
• Usually it is seen in older, thin mares due to abnormal perineal conformation. In these mares, the anus is pulled forward, which leads to tipping of the vulva dorsally, causing opening of the vagina.
• Therefore, in the surgical repair, it is the dorsal portion of the labia that is tipped cranially that needs to be sutured, and increasing the weight of the mare tends to realign the anatomy appropriately.

Question 149

neonatal encephalopathy

(hypoxic-ischemic encephalopathy)

Answer 149

• This disease can arise from hypoxic conditions in utero or during parturition (dystocia, premature placental separation) resulting in a cascade of biochemical derangements within the body.
• Clinical signs include lethargy, failure to find and nurse from the udder, seizure activity, and in more severe cases damage to the gastrointestinal system and/or kidneys from hypoxia.
• Many foals are hypercapnic because the respiratory center within the CNS is not operating normal.

Question 150

Fistulous Withers

Answer 150

• Inflammation of the Supraspinous bursa
• Fistulous withers is a chronic inflammatory disease of the bursa, the sac-like container of lubricating fluid near the spine of the horse, caused by either infection, parasites, or physical factors.
• Swelling of the withers, drainage of pus from an open lesion resulting from inflammation, and infection that spreads from the infected bursa to surrounding tissues are common characteristics of the disease
• This bursa is variable in size and location but is usually found between the second and fifth thoracic vertebrae and can extend ventrolaterally to the margin of the scapular cartilage. The etiology is thought to be infectious.
• Brucella abortus has been identified in up to 80% of clinical cases by serology and culture.
• Treatment consists of flushing the fistula and appropriate antibiotics

Question 151

Treatment options for EPM

Answer 151

Treatment options for EPM include:

1) Ponazuril (Marquis) antiprotozoal paste
2) Diclazuril (Protazil) antiprotozoal pellets
3) Nitazoxanide (Navigator) antiprotozoal paste
4) Sulfadiazine-pyrimethamine combination

Question 152

Infections from ____ are most commonly associated with melting corneal ulcers in horses

Answer 152

• Pseudomonas

Question 153

Thoroughpin

Answer 153

• Thoroughpin is the term for effusion of the tarsal sheath (sheath of the deep digital flexor).

Question 154

Which condition is associated with apical fracture of the proximal sesamoid bones, avulsion fractures of the palmar aspect of the third metacarpal bone, or fractures of the distal third of the small metacarpal bones in horses?

Answer 154

• suspensory ligament desmitis

Question 155

In a foal with uroperitoneum, the creatinine in the abdominal fluid will be at least _______ as much as the serum creatinine

Answer 155

TWICE

• This finding is diagnostic for a uroperitoneum. In a foal, this is usually due to urinary bladder rupture at the time of parturition due to large pressures exerted on the urinary bladder during parturition.

Question 156

“Scratches”

Answer 156

• Scratches is a condition of chronic seborrheic dermatitis of the palmar/plantar aspect of the pastern.
• The condition is sometimes referred to by several other names including “grease heel”, “dermatitis verrucosa”, “dew poisoning” and “mud fever”.
• It is not specific to the underlying infectious cause but the condition is generally associated with horses kept in wet or muddy environments.
• Treatment involves removing the horse from the wet environment, clipping the surrounding hair, and gently washing and cleaning the area with a disinfectant followed by careful drying.
• Topical ointments or astringent dressings may sometimes be used. The best prevention is to keep horses in a dry and clean environment and maintain good hygiene practices.

Question 157

Prognosis of Horses with EPM

Answer 157

• Most horses improve with treatment but relatively few make a complete recovery
• 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 parasite or re-exposure

Question 158

Large Colon Volvulus

Answer 158

• A volvulus is when a loop of intestine twists around itself and the mesentery that supports it, resulting in a bowel obstruction
• Typically, horses with this problem demonstrate rapid onset of severe unrelenting pain and often occurs in postpartum broodmares.
• Gas distension of the colon may be significant and result in respiratory compromise because the distended colon presses on the diaphragm.
• Gastric reflux may not be present as the small intestine may not be obstructed in this process
• This is a surgical emergency; if surgery or necropsy is performed, the volvulus is typically located at the mesenteric attachment of the colon to the dorsal body wall.
• Because of the rapid onset, the prognosis is guarded to poor in many cases.

Question 159

How is equine viral arteritis transmitted?

(EVA)

Answer 159

Venereally

• EVA may also be transmitted via aerosolized secretions.
• Most infections are asymptomatic in adults, but clinical signs may include fever, lethargy, anorexia, edema, oculo-nasal discharge, and petechia.
• In foals, severe respiratory distress, leukopenia, thrombocytopenia, and death after 12-24 hours can occur.

Question 160

Is Strangles a reportable disease in the USA?

Answer 160

• YES
• As of 2017, S. equi is a reportable disease in all states within the US

Question 161

What is the definitive host for the causative agent of equine protozoal myelitis/myeloencephalitis?

Answer 161

• OPOSSUM
• This is a must-know fact. The opossum is the definitive host for Sarcocystis, the causative agent of equine protozoal myelitis.​
• Other definitive hosts of sarcocystis: coyotes, snakes

Question 162

Equine Aural Plaques?

Tx?

Answer 162

• Lesions do not typically regress but a 2010 study (Veterinary Dermatology; 21(5) 503-509) showed that topical application of imiquimod cream was efficacious in causing resolution of the lesions.
• Environmental insect control is also a wise recommendation in this case but would not lead to regression of the lesions.

Question 163

Mare Reproductive Loss Syndrome

Answer 163

• In the Spring of 2001, a syndrome later termed Mare Reproductive Loss Syndrome, also known as MRLS, occurred in central Kentucky
• Abortions occurred in either early or late gestation and were called early fetal loss and late fetal loss, respectively.
• noted neonatal foal deaths and fibrinous pericarditis as well
• The exact pathogenesis of MRLS is still unknown, but the presence of eastern tent caterpillars was strongly associated with the disease.
• Later, experimental studies in which pregnant mares were exposed to or fed, via NG tube, eastern tent caterpillars resulted in early and late fetal loss.

Question 164

Sidebone

Answer 164

• Sidebone is a common condition of horses, characterized by the ossification of the collateral cartilages of the coffin bone.
• These are found on either side of the foot protruding above the level of the coronary band
• Sidebone develop more commonly in the front rather than the hind feet and are more frequently seen in the heavy (draft) breeds of horses than the lighter breeds
• Sidebone can be associated with lameness but many horses with sidebone are not lame and horses with sidebone are not thought to be predisposed to developing lameness as a result.
• Therefore, it is generally believed that in the absence of lameness or local sensitivity, sidebone should not affect the purchaser’s opinion of a horse’s soundness

Question 165

What is the most common neoplasia seen in the equine stomach?

Answer 165

Squamous Cell Carcinoma