Small Ruminants Flashcards
Which of the following organisms is known to be a blood sucker of the abomasum in sheep and goats?
- Fasciola gigantica
- Ostertagia ostertagii
- Strongyloides spp
- Haemonchus contortus
Answer: Haemonchus contortus
Explanation
The correct answer is Haemonchus contortus.
Ostertagia is not considered a blood sucker; instead this organism invades the abomasal wall.
Strongyloides spp are intestinal threadworms that migrate to the intestines by first penetrating the oral mucosa or the skin, entering the bloodstream, and then heading for the heart. Afterward, they travel to the lungs and trachea, where they are swallowed and enter the intestines. Fasciola gigantica is a liver fluke.
A farmer comes to you because many of his sheep are dying acutely. You perform a necropsy which shows dark blue, hemoglobin filled kidneys. This is most consistent with what condition of sheep?
- Iron deficiency
- Leptospirosis
- Urea toxicity
- Copper toxicity
Answer: Copper toxicity
Explanation
The correct answer is copper toxicity. Sheep are highly susceptible to copper toxicity. Because this causes an acute hemolytic crisis, the most common signs are acute death, icterus, depression, hemoglobinuria, increased respiratory rate, and weakness. Pathology often shows dark, hemoglobin filled kidneys (“gun metal blue”). Goats and cattle are less susceptible to copper toxicity.
***PowerLecture: Nutritional Management and Diseases
Several members of a recently shorn flock of sheep have developed abscesses in the mandibular, prescapular, parotid, and prefemoral lymph nodes. You lance an abscess and obtain some of the thick, white to greenish pus for culture. After growing on an agar plate for 48 hours you note that there are several small whitish-to-opaque colonies which can be easily pushed across the plate like a hockey puck. What is your diagnosis?
- Staphylococcus aureus
- Streptococcus ovis
- Corynebacterium pyogenes
- Corynebacterium pseudotuberculosis
Answer: Corynebacterium pseudotuberculosis
Explanation
Corynebacterium pseudotuberculosis causes caseous lymphadenitis in sheep and goats. The clinical signs and culture results are classic for C. pseudotuberculosis (especially the hockey puck feature).
***PowerPage: Top 10 Sheep and Goat Diseases
***PowerLecture: Caseous Lymphadenitis
Many young (<9 months) rams in a herd develop swelling and edema around the head and neck. There is a serohemorrhagic exudate and local tissue necrosis. What is the most likely cause?
- Clostridium novyi type A
- Corynebacterium pseudotuberculosis
- Mycobacterium bovis
- Clostridium chauvoei
Answer: Clostridium novyi type A
Explanation
The correct answer is Clostridium novyi type A. Cl novyi type B causes Black disease, a liver disorder, in sheep.
Type C is usually nonpathogenic. Type D is also called Cl hemolyticum and causes redwater (bacillary hemoglobinuria) in cattle and sheep.
This is a description of bighead, a disease in young rams where the clostridial organism, which is present in soil and feces, enters through wounds received from head butting and causes the signs described.
Treatment is generally debridement, disinfection, and penicillin.
***PowerPage: Clostridial Diseases
Infection of the pregnant ewe with what virus can result in lambs that have dark and hairy fleece around the head and shoulder that grow poorly and tremor?
- Bluetongue virus
- Akabane virus
- Cache Valley Virus
- Border disease virus
Answer: Border disease virus
Explanation
The correct answer is border disease virus. Ewes infected during gestation can have lambs that are aborted, macerated, or mummified but surviving ones may exhibit the “hairy shaker” syndrome described due to infection of hair follicles and the cerebellum. The other viruses listed can cause abortions but cause different signs in the lambs. Bluetongue can cause hydranencephaly. Akabane can cause dystocia and arthrogryposis.
Cache Valley virus can cause brachygnathia, hydranencephaly, microencephaly, and spinal cord hypoplasia.
***PowerPage: Border Disease
You are called to a goat dairy in Mississippi and asked to perform a postmortem on several 3- to 5-month old kids, which are pale. You note that the abomasum contains many Haemonchus contortus. Other animals of various ages appear anemic (pale, rapid HR, and weak). The owner has been treating all her goats with fenbendazole at two-month intervals for several years now. What is the explanation for this anemia likely to be?
- Hypobiotic larvae
- Resistant parasites
- Iron deficiency anemia
- Copper deficiency anemia
- Vitamin B12 deficiency
Answer: Resistant parasites
Explanation
Haemonchus is a blood sucker and causes anemia. Haemonchus, Ostertagia, and some other trichostrongyles can become resistant to anthelmintics. In addition, some anthelmintics are not as effective against hypobiotic larvae. You should recommend several management changes and use a new anthelmintic such as ivermectin.
**PowerPage: Caprine Intestinal Worms
**PowerLecture: Intestinal Worms
What is the cause of grass tetany in goats?
- Magnesium toxicity
- Calcium deficiency
- Copper deficiency
- Mycotoxins
- Magnesium deficiency
Answer: Magnesium deficiency
Explanation
The correct answer is magnesium deficiency. Magnesium is important for nervous system function and many enzymatic reactions. The skeletal reserves of magnesium are much smaller than the calcium reserve.
Magnesium deficiency leads to grass tetany. Magnesium toxicity is rare. Grass tetany usually occurs in lactating animals in the early spring on pastures that are well-fertilized with nitrogen and potassium, because high levels of these inhibit magnesium absorption from the Gl tract. Copper deficiency causes enzootic ataxia. If you chose mycotoxins, you were probably thinking of grass staggers, which is a different disease.
What species are primarily affected by both internal and external caseous lymphadenitis, a manifestation of Corynebacterium pseudotuberculosis?
- Goats and pigs
- Pigs and horses
- Cows and sheep
- Sheep and goats
- Horses and cows
Answer: Sheep and goats
Explanation
The cutaneous abscesses caused by this organism also affect cattle. Horses experience pectoral abscesses, internal abscesses, and other sites, as well ulcerative lymphangitis (also caused by C. pseudotuberculosis) of the limbs.
***PowerLecture: Caseous Lymphadenitis
Bluetongue will affect primarily which species with clinical signs of illness?
- Goats
- Cows
- Horses
- Sheep
- Pigs
Answer: Sheep
Explanation
The correct answer is sheep. Cattle may suffer reproductive losses, but they rarely show clinical signs of the systemic disease. Culicoides gnats vector bluetongue virus. Bluetongue is in the Reoviridae family. In sheep, the virus causes vasculitis and leakage of serum resulting in initial signs that include fever, edema of the face, muzzle, lips, and ears, and respiratory difficulty. Ptyalism and hyperemia will also be present. You can expect to see large amounts of mucopurulent nasal discharge. The tongue might be cyanotic (hence the name of the disease). Oral lesions will be present that will progress to ulcers and thus need to be differentiated from other ulcer producing diseases such as foot-and-mouth disease. Pulmonary edema and lameness are also often present. Bluetongue also causes teratogenic and reproductive effects both in sheep and cattle. If you see a picture of a stillborn or weak calf with “white eye calf syndrome” it is possibly a result of being infected with bluetongue. These calves have white eyes because they are born with congenital cataracts.
***PowerLecture: Blue Tongue
Which of the following disorders of goats can be controlled by genetic testing?
- Beta mannosidosis
- Penile papillomas
- Scrapie
- Corynebacterium pseudotuberculosis
Answer: Beta mannosidosis
Explanation
Beta mannosidosis is a disorder of Anglo-Nubian goats that causes fatal neurological symptoms in newborns and is an autosomal recessive mode of inheritance.
Scrapie is a prion-cused disorder. In sheep, scrapie can be controlled by genetic testing to eliminate the susceptible animals. To date that is not possible with goats. Corynebacterium pseudotuberculosis is a bacterial disease known as boils. Papillomas are viral.
What are the most common etiological agents of contagious footrot in sheep?
- Prevotella melaninogenicus and Fusobacterium necrophorum
- Dermatophilus congolensis and Fusobacterium necrophorum
- Trueperella pyogenes and Dichelobacter nodosus
- Dichelobacter nodosus and Fusobacterium necrophorum
Answer: Dichelobacter nodosus and Fusobacterium necrophorum
Explanation
Remember, these pathogens are highly contagious in sheep. As with cattle, the lesion will be in the interdigital space.
Trueperella pyogenes (formerly Arcanobacterium pyogenes) may cause footrot in cattle.
Prevotella melaninogenicus is one of the main causes of footrot in cattle, along with Fusobacterium necrophorum.
Dermatophilus congolensis is responsible for strawberry footrot in sheep. 10% zinc sulfate foot baths can be used to treat.
Lameness in sheep and goats due to infectious footrot is associated with wet conditions. What microorganism is considered essential for the disease to occur?
- Brucella ovis
- Corynebacterium pseudotuberculosis
- Campylobacter jejuni
- Dichelobacter nodosus
- Fusobacterium necrophorum
Answer: Dichelobacter nodosus
Explanation
Formerly called Bacteroides nodosus, this organism is the key to diagnosing infectious (contagious) footrot.
Fusobacterium necrophorum is also often present as a secondary invader in cases of footrot.
A male goat presents for vocalizing and straining to urinate. He has been kicking at his abdomen. You detect crystals adherent to the hairs around the prepuce (see image). What condition should you suspect and try to rule out first?
- Lower intestinal obstruction
- Urinary tract obstruction
- Acute severe pyelonephritis
- Upper intestinal obstruction
Answer: Urinary tract obstruction
Explanation
The correct answer is urinary tract obstruction due to calculi. This should be suspected in all male and castrated male goats (and sheep) with non-specific signs of disease or discomfort because it is so common. Common clinical signs associated with urinary tract obstruction are vocalization and dribbling of urine. Heaving or forceful abdominal contractions may be seen. Hematuria, dysuria, prolonged urination, and apparent abdominal pain are also common signs. The most important step of evaluation is exteriorization of the penis and examination of the urethral process because this is the most common site of blockage. In severe cases the entire urethra may be filled with calculi.
***PowerLecture: Urolithiasis In Ruminants
Several young sheep (3-4 months old) in a flock are showing signs of depression, head pressing, opisthotonos, diarrhea and blindness. As you investigate this problem, you realize that the farmer has been mistakenly feeding them horse feed. What disease do the sheep most likely have?
- Polioencephalomalacia
- Brain abscesses
- Hepatic encephalopathy
- Listeriosis
Answer: Polioencephalomalacia
Explanation
The correct answer is polioencephalomalacia (thiamine deficiency). This most commonly occurs in lambs being fed diets that are high in concentrates or molasses such as horse feed. This occurs because in normal lambs, ruminal bacteria produce sufficient thiamine to meet their requirements. Excess feeding of concentrates leads to ruminal acidosis, decreases the population of thiamine-producing bacteria, and increases production and activity of ruminal thiaminase. Other causes of polioencephalomalacia are bracken fern ingestion due to thiaminase in the plant, overdose of amprolium which is a thiamine analog, and high dietary sulfate.
Clinical signs include cortical blindness, head pressing, and incoordination progressing to recumbency, opisthotonos and convulsions. Treatment is with thiamine replacement. Diagnosis is usually based on clinical signs and necropsy findings, but blood thiamine levels and erythrocyte transketolase activity can be measured.
Classic necropsy lesions are a soft, edematous cerebral cortex with gray-yellow discoloration and flattened gyri.
***PowerPage: Top 10 Sheep and Goat Diseases
A farmer complains to you that many of his sheep have been doing poorly. You visit his flock and find many listless, emaciated adult sheep that are dyspneic and tachypneic. The sheep have normal temperatures, appetites, and no adventitious lung sounds. What is your top differential?
- Oestrus ovis infestation
- Ovine Progressive Pneumonia
- Pasteurella pneumonia
- Chlamydia psittaci pneumonia
Answer: Ovine Progressive Pneumonia
Explanation
Ovine Progressive Pneumonia is caused by a lentivirus, also known as Maedi-Visna virus. This generally causes a chronic, progressive condition, and affected sheep tend to be afebrile and maintain their appetites as long as they do not develop secondary bacterial pneumonia. This is in contrast to Pasteurella pneumonia, which tends to be much more acute. Clinical signs of Oestrus ovis tend to be more confined to the nares. Chlamydial pneumonia is rare in sheep.
Which of the following organisms is known to be a blood sucker of the abomasum in sheep and goats?
- Haemonchus contortus
- Strongyloides spp
- Fasciola gigantica
- Ostertagia ostertagii
Answer: Haemonchus contortus
Explanation
The correct answer is Haemonchus contortus. Ostertagia is not considered a blood sucker; instead this organism invades the abomasal wall. Strongyloides spp are intestinal threadworms that migrate to the intestines by first penetrating the oral mucosa or the skin, entering the bloodstream, and then heading for the heart. Afterward, they travel to the lungs and trachea, where they are swallowed and enter the intestines. Fasciola gigantica is a liver fluke.
An adult sheep presents with clinical signs of shaking its head, rubbing its nose, and stomping its feet. It has mucopurulent nasal discharge, stridor, and is sneezing. What insect is most likely responsible for this sheep’s signs?
- Simulium
- Culicoides
-Melophagus ovinus - Oestrus ovis
- Tabanus
Answer: Oestrus ovis
Explanation
The correct answer is Oestrus ovis. This fly deposits larvae in the nostrils of the sheep using its ovipositor. The larvae migrate up the nasal passage into the dorsal turbinates and sinuses where they develop for weeks before coming out. Excessive infestations result in clinical signs and may elicit a hypersensitivity reaction.
What is the most common cause of infectious abortion in sheep in North America?
- Leptospira
- Bluetongue virus
- Campylobacter
- Coxiella
- Brucella
Answer: Campylobacter
Explanation
Campylobacter infection (or vibriosis) is the most significant cause of abortion in sheep in North America. C. jejuni is the most common and C. fetus is the other main cause of abortion. Other common causes are Toxoplasma and Chlamydia psittaci. Bluetongue is much less common. Brucella ovis rarely causes abortion in sheep although it does cause epididymitis. Sheep are not very susceptible to abortion from leptospirosis. Q fever, or Coxiella burnetii, is an uncommon cause of abortion and is more of concern due to zoonotic potential.
A goat dairy is experiencing diarrhea 2 to 3 weeks after weaning at 6 weeks of age. You find numerous Eimeria oocysts in the feces. In addition to improving sanitation in the kid pens and decreasing exposure to Eimeria, which of the following can also be recommended?
- Feed coccidiostat preventative to kids starting at weaning
- Treat all kids at weaning with tetracyclines for 5 days
- Treat all kids for 5 days with Ivermectin at weaning
- Vaccinate against Eimeria caprina
Answer: Feed coccidiostat preventative to kids starting at weaning
Explanation
Amprolium and other preventive drugs can be effectively used to suppress clinical coccidiosis. There is no vaccine.
***PowerPage: Top 10 Sheep and Goat Diseases
A farmer complains to you that many of his sheep have been doing poorly. You visit his flock and find many listless, emaciated adult sheep that are dyspneic and tachypneic. The sheep have normal temperatures, appetites, and no adventitious lung sounds. What is your top differential?
- Ovine Progressive Pneumonia
- Chlamydia psittaci pneumonia
- Oestrus ovis infestation
- Pasteurella pneumonia
Answer: Ovine Progressive Pneumonia
Explanation
Ovine Progressive Pneumonia is caused by a lentivirus, also known as Maedi-Visna virus. This generally causes a chronic, progressive condition, and affected sheep tend to be afebrile and maintain their appetites as long as they do not develop secondary bacterial pneumonia.
This is in contrast to Pasteurella pneumonia, which tends to be much more acute. Clinical signs of Oestrus ovis tend to be more confined to the nares.
Chlamydial pneumonia is rare in sheep.
A 3-year old Nubian male goat presents with a history of breaking into a bag of grain meant for horses. What disease process are you concerned about?
- Rumen acidosis (grain overload)
- Acute hypocalcemia
- Rumen alkalosis
- Abomasal impaction
Answer: Rumen acidosis (grain overload)
Explanation
The correct answer is acute rumen acidosis. Excessive consumption of grain or other readily fermentable carbohydrate will lead to replication of Streptococcus bovis and other gram positive bacteria in the rumen at first, lowering the rumen pH precipitously to below 4.5 and causing an increase in lactic acid. Lactobacilli will subsequently multiply due to the favorable conditions created. The goat cannot metabolize the D-lactic acid made by bacteria (mammals can only process L -Lactic acid which they produce themselves), and a systemic lactic acidosis results. Clinical signs include rapid HR, depression, anorexia, fluid-filled rumen, scleral injection, staggering, diarrhea after 24 hours, and damage to rumen mucosa.
***PowerPage: Top 10 Sheep and Goat Diseases
Which of these routes are likely methods of transmission of Mycoplasma pneumonia in goats?
- Venereally and via insect vector
- Transmammary and aerosol
- Transplacental and fecal-oral
- Via blood transfusion and urine contamination
Answer: Transmammary and aerosol
Explanation
The correct answer is transmammary and aerosol. In goats, Mycoplasma pneumonia is caused by the Mycoplasma mycoides subspecies mycoides ( large colony type) and M. capricolum. The organism is transmitted orally to kids through contaminated milk or colostrum. In adults, it is thought to be transmitted through the external auditory meatus or direct inhalation. The incubation period is approximately 6-10 days but can be up to several weeks. Affected animals will typically show signs of respiratory disease (fibrinous pneumonia).
Several kid goats age 10 to 12 weeks on a large goat dairy have developed high fevers, swollen and painful joints, and respiratory signs including tachypnea and dyspnea. One has died, and a post mortem exam reveals fibrinopurulent polyarthritis and interstitial pneumonia. Which is the agent most likely to be the cause of this outbreak?
- Corynebacterium pseudotuberculosis
- Trueperella pyogenes (formerly Arcanobacterium pyogenes)
- Mycoplasma mycoides ssp. mycoides
- Pasteurella multocida
- Mannheimia hemolytica
Answer: Mycoplasma mycoides ssp. mycoides
Explanation
Mycoplasma mycoides subsp. mycoides of the large-colony (LC) type is responsible for major problems in the US goat population. It can also cause acute septicemia and CNS signs in kids. Carrier goats maintain the infection in a herd, where it is transmitted to kids through milk or colostrum.
A sheep presents to you with a history of rubbing its wool raw in areas along the lumbar regions. The sheep has had substantial weight loss in the past few months and has become quite fractious. What is the most likely diagnosis?
- Bacterial meningitis
- Listeria monocytogenes
- Rabies
- Scrapie
Answer: Scrapie
Explanation
The correct answer is scrapie. Scrapie is an afebrile neurologic disease of sheep that is a chronic, progressive, degenerative neurologic disease. It is one of the transmissible encephalopathies (like mad cow disease) caused by a prion. Clinical signs depend on the regions of the brain that are affected but usually include behavior changes including aggressiveness, failure to herd, unsteady gait, floppy ears, self-mutilation (pruritus), and in end stages, blindness, seizures, and an inability to swallow. Rabies is a differential for this sheep although clinical signs of rabies are usually more rapid in progression, with an ascending paralysis. However, aggression and any other neurologic signs can be seen with rabies. Bacterial meningitis in sheep is frequently associated with tail docking and presents as a progressive ascending paralysis. Neck pain is also frequently present. Clinical signs of listeriosis are usually loss of the ability to eat, dehydration, and often asymmetrical cranial nerve V or XII signs, including dropped jaw, loss of saliva, and dysphagia.
**PowerPage: Top 10 Sheep and Goat Diseases
**PowerLecture: Scrapie
Several ewes in a large flock, all of which are in late gestation, have not been able to rise to the standing position. They are being fed good quality grass and alfalfa hay. It is December and the weather is cold. They have reduced feed intake and the most severely affected individuals appear blind and depressed. The physical exam is otherwise not very revealing except that all have significant ketonuria. Which of the following disorders is the most likely and must be ruled out?
- Hypomagnesemia
- Amsinckia toxicity
- Liver flukes
- Pregnancy toxemia
- Type 2 ostertagiasis
Answer: Pregnancy toxemia
Explanation
Pregnancy toxemia is the result of multiple fetuses and insufficient energy intake in late gestation. Cold weather increases energy needs and often precipitates this disorder. Being overweight initially seems to make this disorder more likely. Affected ewes often have low calcium and potassium and high beta-hydroxybutyrate levels.
***PowerLecture: Reproductive Management
A sheep presents in a sitting position with apparently normal forelimbs and hyperreflexia of the hind limbs. Where would you localize the lesion to?
- Cerebrum
- C6-2 myelopathy
- L4-S3 myelopathy
- T3-L3 myelopathy
- Brainstem
Answer: T3-L3 myelopathy
Explanation
The correct answer is T3-L3 myelopathy. With a T3-L3 myelopathy, thoracic limbs would be normal because the nerve roots to the limbs emerge from the spinal cord cranial to the injury. Hyperreflexia to the pelvic limbs is an upper motor neuron sign indicating a lesion cranial to L4. A C6-2 myelopathy would cause lower motor neuron signs to the thoracic limbs. Cerebral and brainstem lesions would be unlikely to cause this type of lesion distribution.
A sheep presents to you for nasal discharge and face rubbing. You perform cytology on the copious discharge and note numerous eosinophils and mast cells. What is the most likely diagnosis?
- Actinomyces sinusitis
- Melophagus ovinus infestation
- Oestrus ovis infestation
- Enzootic nasal tumor
- Sheep diphtheria (Fusobacterium necrophorum)
Answer: Oestrus ovis infestation
Explanation
The correct answer is Oestrus ovis infestation. Adult flies deposit larvae around the animals’ nostrils; the larvae then migrate up the nasal passages into the turbinates and sinuses. With time and multiplication of the larvae, hypersensitivity develops with the marked clinical signs of nasal discharge and face rubbing and shaking.
Secondary bacterial infection can occur. The discharge usually contains numerous eosinophils and mast cells, which confirms the diagnosis in this case. Further confirmation could be achieved with radiographs showing mineralized bots or with endoscopy, but this is not usually necessary.
Enzootic nasal tumor could have similar clinical signs but tends to cause more dyspnea and would not have the eosinophils and mast cells seen in the discharge.
Fusobacterium causes necrotic laryngitis in sheep when there is perforation to the mucous membranes. Clinical signs are more of coughing and dyspnea; there would not be nasal discharge.
Actinomyces pyogenes infection is also unlikely to cause nasal discharge and if it did, you would not observe eosinophils and mast cells in the discharge.
Treatment of Oestrus ovis is with ivermectin.
You examine a herd of sheep and find that many sheep have proliferative, crusting lesions of the mucocutaneous junctions of the mouth and nose. They are otherwise relatively healthy, although some of the nursing females have similar lesions on their udders. The farmer reports that many of his sheep have had these before and that it eventually just goes away. What is the most likely diagnosis?
- Vesicular stomatitis
- Foot-and-mouth disease
- Bluetongue
- Contagious ecthyma
Answer: Contagious ecthyma
Explanation
The correct answer is contagious ecthyma. FMD, VSV, and bluetongue cause vesicles and ulcers rather than proliferative, crusting lesions and usually will have other systemic signs as well; also, they are unlikely to recover spontaneously. Contagious ecthyma is a zoonotic poxvirus.
What is the most common site of obstruction in male goats with urolithiasis?
- External urethral sphincter
- Urethral process
- Trigone
- Internal urethral sphincter
Answer: Urethral process
Explanation
The correct answer is the urethral process. The most common sites of obstruction in male goats are the urethral process and the distal sigmoid flexure. This is because these regions are narrower intraluminally and are physically predisposed to getting calculi stuck. Other sites including the trigone, ureter, and renal pelvis can obstruct from stones but are less common sites. Even when this obstruction is removed, re-obstruction commonly occurs as more stones leave the bladder.
***PowerLecture: Urolithiasis In Ruminants
A 3-day-old Suffolk male lamb presents in sternal recumbency with increasing abdominal distension and mild colic (see image). The lamb was bright and alert for the first 2 days of life but has since stopped suckling its dam. Clinical examination reveals that the lamb has no anus. What should you recommend?
- Medical management with antibiotics and analgesics are necessary until the problem resolves
- This is normal in lambs and will resolve within 1-2 weeks
- Surgical correction is frequently successful
- There is no effective treatment and the lamb should be euthanized
Answer: ** Surgical correction is frequently successful
Explanation
Atresia of the colon, rectum and anus can all occur congenitally. Often, the clinical sign first noted is progressive abdominal distension. In this case, atresia ani was detected on clinical exam but atresia of the colon or rectum may require radiography to diagnose. Surgical establishment of anal patency can be performed for atresia ani whereas a permanent colostomy may be required for atresia of the colon and rectum.
If surgical correction is attempted, the animal should probably be neutered because of the potential genetic basis for this condition. To perform the surgical correction, a slight bulge in the skin may be present where the anus should be located in lambs or ultrasound can be used to detect the fluid filled rectum. After surgical preparation and local anesthetic injection, an incision to remove the skin over the rectum should be made.
Dost-cureically antibiotice and either mineral oil DeS or stool coftenere chould he diven as needed if noccible Post-surgically, antibiotics and either mineral oil, DSS, or stool softeners should be given as needed. If possible, twice daily insertion of a thermometer to prevent stricture is preferred.
You have encountered white muscle disease in a large commercial flock of sheep, and wish to examine the selenium status of the flock. You decide to collect samples. What samples should be collected in order to accurately assess the selenium status of the flock?
- Urine for 20 random sheep to determine
glutathione peroxidase activity - Blood from 20 random sheep for creatine
kinase levels - 20 random pasture samples for Selenium
analysis - Serum from 20 random sheep to determine
vitamin E levels - Whole blood from 20 random sheep to determine selenium levels
Answer: Whole blood from 20 random sheep to determine selenium levels
Explanation
Whole blood selenium is preferred over plasma or serum levels.
If animals fall below 0.05 ppm Se, most of the animals will benefit from Se supplementation.
Those with marginal Se (0.05 to 0.06 ppm) may sometimes also benefit, while those over 0.07 ppm are considered normal.
The image shows a one-month old lamb from an unvaccinated commercial flock which is unable to stand and shows muscle spasms and rigidity when stimulated. The lamb was tail docked and castrated at 3 days of age using elastrator bands on the tail and scrotum. What is the most likely diagnosis?
- Selenium deficiency and white muscle disease
- Spina bifida
- Cerebellar hypoplasia
- Tetanus
- Spastic syndrome
Answer: Tetanus
Explanation
Since the lamb was from an unvaccinated ewe and was neither given tetanus antitoxin nor vaccinated against tetanus, the compatible clinical signs make tetanus the most likely correct diagnosis.
A 2-year old registered Suffolk sheep has developed weight loss, nervousness, and pruritus, resulting in loss of much of its wool (see image). It has recently developed ataxia and teeth grinding. On the basis of these clinical signs you make a tentative diagnosis of scrapie. If scrapie is confirmed, what is the best approach to managing the flock?
- Treat affected animals for 2 weeks with IM tetracyclines
- Use stem cell therapy to insert the PrP gene into affected animals and related animals
- Use corrals and pastures where the affected animal had been only for lambs under a year of age for the next year
- Cull positive animals and treat all others in the flock with immunostimulants
- Cull positives and breed for resistant flock based on pedigree
Answer: Cull positives and breed for resistant flock based on pedigree
Explanation
Scrapie is a spongiform encephalopathy, caused by a prion. The PrP gene appears to play a role in susceptibility.
Using known pedigrees (breed only unaffected animals) or genetic testing, a resistant or less susceptible flock can be bred. Affected and related animals should be culled and destroyed, as the prion may otherwise spread the disease.
A 5-year old ewe presents as a result of isolating herself. She had just twinned two months ago and she is not vaccinated. On physical examination, she has an enlarged left half of the udder. It is cold, blue, and black (see image). Serosanguinous milk can easily be expressed, and it is foul-smelling. With treatment, what is the prognosis for sheep with this condition?
- Excellent (over 90% of affected sheep recover fully)
- Grave (over 80% of affected sheep die or are euthanized)
- Good (over 80% of affected sheep will recover and have adequate function)
- Fair (less than 50% of affected sheep die or are euthanized)
Answer: Grave (over 80% of affected sheep die or are euthanized)
Explanation
Gangrenous mastitis is caused by Mannheimia spp. and Staphylococcus aureus and occurs sporadically during the first 3 months of lactation. It is generally associated with poor milk supply related to ewe undernutrition and over vigorous suckling by the lambs.
Despite antibiotic and supportive therapy, the prognosis is grave, and gangrenous udder tissue eventually sloughs leaving a large granulating surface with superficial bacterial infection. The granulation tissue continues to proliferate over the coming months. These ewes are unsuitable for breeding stock. The infected granulation tissue and resultant drainage lymph node enlargement would result in carcass condemnation (and raise genuine welfare concerns). The fleece is very poor because growth has occurred during this period of illness.
Affected ewes should be euthanized for welfare reasons at first presentation.
Control measures include ensuring ewes are well fed. Concentrates should be supplied to ewes and lambs when pasture is poor. No ewe should be expected to rear triplets. Teat lesions should be identified and treated with topical antibiotics.
Obstructive urolithiasis (see image of stones in bladder) is most likely to occur in which of the following animals?
- Bull
- Boar pig
- Wether goat
- Female goat (doe)
- Cow
Answer: Wether goat
Explanation
Castration in young animals reduces the diameter of the urethra and goats tend to be prone to developing uroliths. Obstructive urolithiasis occurs most frequently in castrated pygmy goats, then next is castrated males of other breeds of goats. The signs of obstruction are repeatedly posturing to urinate, straining, and vocalizing.
Intact bulls and pigs rarely experience obstructive urolithiasis and females have a large enough diameter urethra to pass most stones.
A 6-month old wether sheep has been straining to urinate. You find the animal to be non-febrile but to have a rapid heart rate and respiratory rate. Ultrasound demonstrates a distended urinary bladder. Using sedation, you find several small stones lodged in the urethral process as shown in the picture. What is the best next step to take?
- Place a percutaneous Foley catheter in the urinary bladder
- Amputate the urethral process and observe for urination
- Pass a retrograde urinary tract catheter and flush the stones back into the bladder
- Perform surgery and pass a catheter from the bladder down the urethra and flush out all stones
- Give urinary acidifiers per os
Answer: Amputate the urethral process and observe for urination
Explanation
Some sheep will only have stones in the urethral process, as it tends to be the narrowest diameter in the urethra. But in many cases there are additional stones in the urethra and/or bladder, and the animal will re-block. At that point, more aggressive procedures are indicated.
***PowerLecture: Urolithiasis In Ruminants
Several young goats under one year of age in a herd of 50 goats have scabby lesions around their mouths and noses, as shown in the photo. They also have low-grade fever and appear reluctant to eat hay, so they are falling behind the group. The owner is concerned because this condition appears to be spreading. You examine three affected kids and find that under the scabs is what appears to be proliferative granulation tissue. You advise the owner that the diagnosis is_______?
- Foot-and-mouth disease
- Bovine papular stomatitis
- Contagious ecthyma
- Malignant catarrhal fever
- Pseudocowpox
Answer: Contagious Ecthyma
Explanation
Also known as orf or soremouth, this parapoxvirus disease is common in lambs and kids. Humans can also be affected. Rarely fatal, it nonetheless can make affected kids or lambs end up smaller than their age mates.
Lesions occasionally also occur on the teats of the dams. The scabs dry up in 2 to 4 weeks and fall off, with the virus overwintering in the scabs on the ground until more susceptible animals appear next year.
***PowerPage: Top 10 Sheep and Goat Diseases
A 1-year old pet wether sheep presents at your clinic with a complaint of restlessness, teeth grinding, vocalizing, stretching out, and straining. When you tickle the preputial opening, only a drop of urine appears. The wether has tachypnea and tachycardia, and is mildly bloated. When you palpate the abdomen externally using both hands, you detect a large turgid structure in the caudal abdomen; you diagnose urethral obstruction due to urolithiasis. You sedate the sheep and extrude the penis, where you find several stones in the urethral process and amputate it (see image of amputated process). The animal is still unable to urinate. What is the best treatment option for this pet now?
- Xylazine and intravenous fluids
- Perineal urethrostomy
- Bladder marsupialization
- Tube cystostomy
- Penectomy
Answer: Tube cystotomy
Explanation
Using local anesthesia, a Foley catheter is inserted percutaneously into the bladder immediately in front of the pubis and sutured in place. This option allows the urine to drain, and the relief often allows the urethal stones to pass. After one or two weeks the animal may once again be able to urinate through the urethra, and the catheter can be removed. The stone type should be determined by analysis and a corrective dietary measure initiated. The other surgical treatments listed are less likely to have favorable long term outcomes and are considered salvage procedures; the other medical treatments would likely result in a ruptured bladder.
***PowerPage: Urethral Obstruction (Small Ruminants)
***PowerLecture: Urolithiasis In Ruminants
You are asked to perform a post mortem examination on a 2-year old sheep recently moved to a feedlot after giving birth to twins in the early summer. The farmer noted no signs of illness prior to finding the sheep acutely dead in the morning. An image of the gross post-mortem finding is shown below. You note widespread necrosis of the small intestine with fetid smelling contents. No volvulus is seen. You evaluate the urine and find glucosuria. There is softening of the brain and kidney tissues. Which of the following management considerations should you look into?
- Evaluate the density of the herd and other causes of stress
- Evaluate pasture for toxic plants and the medication history of the flock
- Evaluate vector control program and shearing protocols
- Evaluate breeding soundness evaluation program and quarantine program for newly introduced sheep
- Evaluate herd vaccination program and diet
Answer: Evaluate herd vaccination program and diet
Explanation
You should be suspicious of type D Clostridial enterotoxemia based on the acute mortality and necropsy lesions in the intestines. Additional findings consistent with enterotoxemia are the glucosuria and soft kidneys.
Enterotoxemia is sometimes referred to as overeating disease because of its association with changes in diet to concentrates or higher grain concentrations. It is also sometimes referred to as pulpy kidney disease because of the changes that occur to the kidneys.
Enterotoxemia caused by Clostridium perfringens type D affects sheep and goats of all ages (from 1 week to several years of age).
A diagnosis of enterotoxemia is suggested when the sudden death of concentrate-fed animals that have not been vaccinated for Clostridium perfringens type D occurs.
In young animals, this commonly occurs after abundant nursing or grazing on improved pastures, high quality hays and/or concentrates/grains. In older animals as in this case, the disease corresponds with the finishing or feedlot period and is often associated with a high grain diet. Enterotoxemia is one of the most common causes of death in feeding lambs.
Prevention depends on vaccination against Clostridial toxoid and avoiding rapid changes in diet.
A 6-month old lamb presents with a left-sided head tilt and spontaneous horizontal nystagmus with the fast phase directed towards the right side, and changes with the position of the head. Ventral strabismus is present on the left side and there is drooping of the left upper eyelid and left ear (see image). Which of the following is the most appropriate differential diagnosis list with most likely conditions listed first?
- Listeriosis. Otitis media
- Facial nerve neuritis, salt poisoning,
- Brain tumor, Mycoplasma mycoides bacteremia
- Rabies, polioencephalomalacia
Answer: Listeriosis. Otitis media
Explanation
Based on the presentation, there is a vestibular lesion as well as a facial nerve lesion. This can occur commonly with middle ear lesions or brainstem disease.
Unilateral peripheral vestibular lesions are commonly associated with otitis media and ascending bacterial infection via the eustachian tube. Sheep typically present with a head tilt towards the affected side. There may be evidence of otitis externa and purulent aural discharge in some cases, but rupture of the tympanic membrane is not a common route of infection. Pasteurella, Streptococcus, and Arcanobacterium have been isolated from infected lesions. Middle ear trauma can also occur. This is usually treated effectively with procaine penicillin if disease is recognized early.
Listerosis is a bacterial infection that may or may not be associated with ingestion of contaminated silage. It usually presents as a bacterial infection limited to one side of the brainstem and involving a few cranial nerves.
Affected sheep may have unilateral weakness, drooping ear and eyelid, and deviated muzzle. If recognized early, it can be effectively treated with antibiotics (penicillin).
This animal is young, making brain tumor unlikely. (It is also rare in ruminants).
Mycoplasma mycoides subsp mycoides is a problem of young goat kids, not lambs. The clinical signs are typically polyarthtitis rather than CNS.
Salt toxicity can develop in sheep if a high percentage of mineral supplement is used and water supply is limited. Signs include salivation, increased thirst, vomiting, abdominal pain, diarrhea, ataxia, blindness, and seizures.
Facial nerve neuritis (due to virus) is not recognized in sheep.
Rabies is usually associated with livestock exhibiting dysphagia, paresis, and paresthesia.
Polioencephalomalacia usually causes clinical signs that include star-gazing, blindness, and aimless wandering which is less consistent with the clinical description here. It is treated with high doses of thiamine.
***PowerPage: Top 10 Sheep and Goat Diseases
