Equine Flashcards
What kind of organism causes equine granulocytic ehrlichiosis? A. Spirochete B. Anaplasma C. Ehrlichia D. Protozoa E. Chlamydia
B
Which one of the following management recommendations is most helpful to reduce the incidence of mare reproductive loss syndrome?
A. Cut down all the black walnut trees on premises
B. Vaccinate mares and stallions against equine coital exanthema
C. Remove the horses from affected pastures
D. Progesterone supplementation between 4-6 months of pregnancy
E. Spray paddocks to kill Habronema muscae larvae
C
Removal of mares from affected pastures is necessary for control of mare reproductive loss syndrome (MRLS).
The exact pathogenesis of MRLS is still unknown, however, it is associated with exposure to/ingestion of “hirsute” or hairy catepillars.
The eastern tent caterpillar was associated with the first outbreak in Kentucky in 2001-2 where over 3000 pregnant mares aborted.
Other episodes have been seen in Florida (2005) and Australia (2007) with exposure to other animals of hirsute catepillars.
The most current theory - damage to the oral mucosa or intestinal lining by the setae (spines) of the catepillars introduces bacteria that causes bacteremia and subsequent infection of the fetus and/or placenta.
Early embryonic loss, abortion, stillbirths, weak foals, and infected foals are seen. Swollen umbilical cords are also often seen in aborted fetuses.
Feeding hay and removal of wild cherry trees, a major food source for the caterpillars, is also beneficial in reducing the incidence of MRLS abortion.
Retained placenta and metritis can predispose to which one of the following secondary conditions in horses A. Laminitis B. Postpartum dysgalactia syndrome C. Contagious equine metritis D. Cystic endometriosis
A
In horses, retained placenta and septic metritis can cause acute laminitis.
Other causes of equine laminitis include:
Grain overload
Overeating lush spring grasses
Insulin dysregulation
Colic, endotoxemia
Exposure to black walnut (Juglans nigra) shavings
Over-exercise on hard surfaces
Lameness on one limb requiring overdependency on opposite leg, which then develops laminitis.
What recommendation should be given to the owner of a mare that has had Caslick’s vulvoplasty surgery?
A - Mare has a higher than normal risk for metritis
B - Mare has a decreased risk for perineal laceration
C - Mare should not be bred by a stallion
D - Mare should not be bred
E - Mare will need an episiotomy before foaling
E
The mare will need an episiotomy (a surgically planned incision on the perineum and the posterior vaginal wall) prior to foaling. Sometimes an episiotomy may be needed prior to breeding by stallion if the remaining vulvar cleft is too small to permit intromission. A Caslick’s operation (vulvoplasty, a superficial form of the episioplasty) is used to treat pneumovagina in horses to prevent genital infections and infertility.
Which one of the following choices is a major clinical complication of equine pituitary pars intermedia dysfunction?
A - Dyshormonogenetic goiter B - Circling, Head-pressing C - Diabetes insipidus D - Colic E - Laminitis
E
The major clinical complication of pituitary pars intermedia dysfunction (PPID, hyperadrenocorticism) is laminitis. Laminitis affects more than 50% of the horses with PPID
A 4-year-old Thoroughbred mare is presented with a sudden onset of profuse, watery diarrhea and marked depression.
The mare has been treated intermittently with phenylbutazone over the last 2 months for minor lameness and was recently transported to the racetrack by trailer for 9 hours.
On physical exam the horse is dehydrated, with a slow capillary refill time, purplish mucous membranes, and cold extremities.
No gastric reflux is present. No distention or displacement of bowel is found with rectal exam, but the rectal wall feels thickened.
T=97.0 F (37.8 C)..[N 99-101.3 F, N=37.2-38.5 C]
HR=92 bpm………….[N 28-40 bpm]
RR=50 brpm…………[N 10-14 brpm]
PCV=70%…………….[N 32-53%]
Total protein 4.0 g/dl …….[N 5.8 - 7.5 g/dl]
The horse dies 3 hours later. On necropsy the walls of the cecum, large colon, and rectum are edematous and hemorrhagic; intestinal contents are primarily serosanguinous fluid.
Which one of the following choices is the most likely cause of death in this mare?
A - Non-steroidal anti-inflammatory toxicity B - Parascaris equorum infestation C - Sand enteropathy D - Granulomatous enteritis E - Colitis X
E
This is the clinical picture of colitis X, a lethal diarrheal disease of horses with an acute to peracute-onset.
The specific cause is unknown, but infectious and toxic etiologies are most likely. Anaphylaxis also produces similar intestinal lesions. Look for signs of shock, peracute severe diarrhea and a packed red cell volume (PCV) above 65%, and sudden death. Some cases may die before diarrhea is seen. The cause is unknown but stress (like transport) or surgery often precedes disease. This is a diagnosis of exclusion
Which two diseases would be on a differential diagnosis list for equine urinary incontinence?
A - Cauda equina neuritis, herpesvirus myeloencephalopathy
B - Equine degenerative myelopathy, botulism
C - Nigropallidal encephalomalacia, locoweed poisoning
D - Bracken fern toxicity, equine encephalomyelitis
E - Tetanus, West Nile virus encephalopathy
A
Cauda equina neuritis and herpesvirus myeloencephalopathy.
Horses with cauda equina neuritis (also called polyneuritis equi) have a progressive symmetric LMN paresis of the tail, bladder, rectum, anal sphincter.
Look for urinary incontinence, fecal retention, and a weak or paralyzed tail. May see hind limb paresis if lumbosacral spinal cord is affected.
Cranial nerves can also be affected, but typically cranial involvement is asymmetric. May see temporal or masseter atrophy (cranial nerve 5), facial paralysis, and exposure keratitis (cranial nerve 7), head tilt, or other CNS signs.
Cause is unknown, may be an autoimmune process. Grave prognosis. Eventually euthanized.
Herpesvirus myeloencephalopathy (EHV-1) may also present with urinary incontinence, but this is a relatively uncommon manifestation of equine rhinopneumonitis. You would expect to hear a history of the more common EHV signs in other horses from the same farm, like respiratory disease (“snots”) in foals and abortions in mares.
Bracken fern toxicity (Pteridium aquilinum) causes thiamine deficiency in monogastrics (like horses) and bone marrow depletion, aplastic anemia, and bladder tumors in ruminants.
In horses, look for signs of anorexia, weight loss, incoordination, and a crouching stance with feet placed wide apart. Horses may have trembling muscles when forced to move.
A 5-year old Arabian mare expels the placenta 2 hours after foaling.
On examination, it appears that the placenta has passed “inside out”, with the allantoic side of the allantochorion exposed.
What is the correct interpretation?
A - Normal finding B - Sign of placental insufficiency C - Suggests premature placental separation D - Do not rebreed this mare E - Foal at risk for peripartum asphyxia
A
It is normal for a horse to expel the placenta “inside out”, with the allantoic side of the allantochorion exposed.
Following parturition, the placenta should be expelled within 3 hours, or it is considered retained in the horse.
A newborn foal is examined two hours after birth.
The foal has a heart rate of 100 bpm [N=100-120], and a continuous murmur loudest on the left side.
Which one of the following choices is the most likely explanation for these findings?
A - Incipient septicemia B - Hypoxic ischemic encephalopathy C - Foal dysmaturity D - Normal in a neonatal foal E - Ventricular septal defect
D
These findings are NORMAL in a neonatal foal.
The heart rate and a finding of a continuous murmur on the left side (due to slight opening of the ductus arteriosus, which usually closes within 4-5 days) are normal in newborn foals.
Persistent patent ductus arteriosus is rare in horses.
Which choice is the pastern joint?
A - Carpometacarpal joint
B - Proximal interphalangeal joint (PI-PII)
C - Distal interphalangeal joint (PII-PIII)
D - Metacarpophalangeal joint
E - Intermetacarpal joint
B
The proximal interphalangeal joint (PI-PII) is the pastern.
Clinically important because one of the 3 most important nerve blocks, the foot block (also called pastern or abaxial sesamoid nerve block (ASNB)) is done just above the pastern.
Can use a pastern block to make a horse with acute laminitis comfortable.
A 10 year old Quarterhorse gelding pastured in the northeastern United States is presented for weakness and depression.
The owner reports that the horse’s urine is an unusually dark brown color.
On physical exam, the horse is tachycardic and tachypneic. The mucous membranes are a dark yellowish brown.
The horse’s plasma has a pink tinge.
A CBC, blood smear, biochemistry panel, and urinalysis indentify intravascular hemolytic anemia, hemoglobinemia, methemoglobinemia, and hemoglobinuria.
Erythrocytes are seen on the blood smear with Heinz bodies and eccentrocytosis.
Ingestion of which one of the following plants is most likely to cause of this spectrum of clinical signs in this case?
A - Tetradymia spp (Horsebrush) B - Quercus spp (Oak) C - Acer rubrum (Red maple) D - Veratrum spp (Skunk cabbage) E - Xanthium spp (Cocklebur)
C
When a foal is being treated with erythromycin (for Rhodococcus equi for example), the mare is at risk of developing enterocolitis due to which one of the following organisms?
A - Escherechia coli B - Clostridium novyi C - Lawsonia intracellularis D - Rhodococcus equi E - Clostridium difficile
E
A history of recent antimicrobial therapy is common in cases of Clostridium difficile associated diarrhea.
Adult horses exposed to erythromycin are particularly at risk for C. difficile enterocolitis.
Clostridium novyi is the cause of infectious necrotic hepatitis, which is primarily seen in sheep but can also be seen in cattle, hogs, and horses.
Rhodococcus equi is a notable cause of pneumonia in older foals characterized by pulmonary abscessation as well as some extrapulmonary manifestations
Foal heat diarrhea is typically associated with which choice?
A - Hemorrhagic enteritis B - Neutropenia and fever C - Decreased suckling D - Alterations in diet E - Warm and humid weather
D
Mild, self-limiting diarrhea in a foal 7-14 days of age is called foal heat diarrhea, because it coincides with the first estrus cycle post-foaling in the dam.
Causes of foal heat diarrhea are poorly understood, but are thought to be related to a foal’s tendency to start sampling hay and grain and practice coprophagy by 5 to 7 days of age, with consequent alterations in bacterial flora.
Foals are active and alert, with a normal appetite and vital signs.
Clinical signs such as fever and lethargy, hematochezia or melena, and laboratory findings such as neutropenia are not routinely observed.
A herd of 12 multiparous broodmares housed on a 25 acre pasture in the southeastern United States are having reproductive problems.
Of the three mares that have foaled so far this year, none have produced milk.
Another mare is now 12 months in foal and has no udder development.
Which one of the following choices is the most likely diagnosis?
A - Mastitis B - Malnutrition C - Placentitis D - Fescue toxicity E - Retained placentas
D
Ingestion of fescue grass contaminated with the endophyte fungus Acremonium coenophialum causes agalactia, thickened placentas, and prolonged pregnancy in mares by suppressing prolactin release.
Mares should be removed from fescue pastures (and not fed fescue hay) for the last 90 days of gestation to reduce the incidence of fescue-associated problems.
Treatment with domperidone can help affected mares produce milk.
Mares with malnutrition are more likely to abort than carry a pregnancy over term.
Retained placenta and metritis can predispose to which one of the following secondary conditions in horses?
A - Laminitis B - Postpartum dysgalactia syndrome C - Contagious equine metritis D - Cystic endometriosis E - Colic
A
In horses, retained placenta and septic metritis can cause acute laminitis.
Other causes of equine laminitis include:
Grain overload
Overeating lush spring grasses
Insulin dysregulation
Colic, endotoxemia
Exposure to black walnut (Juglans nigra) shavings
Over-exercise on hard surfaces
Lameness on one limb requiring overdependency on opposite leg, which then develops laminitis.
