Bovine II Flashcards
A three-week old Jersey calf presents due to an inability to walk. On physical exam, there are no signs of trauma and it is noted that the hocks will not flex due to continuous gastrocnemius tension. There were no other abnormal physical exam findings. What is your primary differential?
- Septic hocks
- Bilateral gastrocnemius rupture
- Spastic paresis
- Tetanus
Answer: Spastic paresis
Explanation
The correct answer is spastic paresis (aka Elso heel). This is a hereditary disease which produces a continuous stiffness of the hocks. There could be bilateral or unilateral involvement. It is a recessive disease; therefore, affected animals should not be bred. Treatment involves a tibial neurectomy or gastrocnemius tenectomy.
Given these signals and clinical signs, spastic paresis should be high on your differential list. Sepsis is highly unlikely because there are no other signs of systemic disease. You would see the opposite clinical signs with a gastrocnemius rupture.
A dairy farmer brings you a 6-week old calf for postmortem exam on a nice warm spring day. He has had three 5- to 7-week old calves die in the last week and this one just died an hour ago. They show depressed appetite, fever, and rapid labored breathing before collapsing within a day from the time the first signs are noticed. The calves were born on his farm and have been in good well-ventilated individual hutches with shade. They are fed 12% of their body weight per day in whole milk, plus a calf starter grain, alfalfa hay and free choice water. The major lesions are serosal and subcutaneous petechial hemorrhages and heavy wet red lungs (see image). Based on these pathologic findings, which of the following is the most likely cause of death?
- Salmonella dublin
- E. coli septicemia
- Malignant catarrhal fever (MCF)
- Bovine virus diarrhea (BVD)
- Mannheimia hemolytica bronchopneumonia
Answer: Salmonella dublin
Explanation
S. dublin tends to cause septicemia in dairy calves 4 to 8 weeks of age, and the lesions described are typical.
The organism can be transmitted by carrier cows to neonates at birth or via their milk. The most effective control measures are to cull carriers and vaccinate calves using a modified live S. dublin vaccine.
***PowerLecture: Diarrhea Part 1
You examine a valuable 4-year old black and white Holstein dairy cow in mid-lactation with the complaint of poor appetite and a sudden decrease in milk production. T=105F (40.6 C), HR=105, RR=30. The heart is muffled and difficult to auscult, and there is a moderate amount of brisket edema present. Rumen motility is poor, but no other abnormalities are noted on abdominal and rectal exams. Of the following which is the most likely cause of her drop in milk production?
- Cardiomyopathy
- Valvular endocarditis
- Traumatic pericarditis
- Brisket disease
- Ventricular septal defect
Answer: Traumatic pericarditis
Explanation
If a metallic foreign body penetrates the reticulum and the pericardium, the resulting infection will lead to large amounts of infected pericardial fluid, which in turn causes constrictive heart disease and heart failure.
Some people refer to this condition as Hardware disease or traumatic reticuloperitonitis. A muffled heart sound along with brisket edema should increase your suspicion for this disease. A ventricular septal defect or valvular endocarditis will likely not result in muffled heart sounds. Cardiomyopathy would not be expected to cause a fever or muffled heart. Brisket disease occurs as a result of lack of oxygen at high altitude. As the syndrome progresses, subacute edema develops in the brisket region. Marked distention and pulsation of the jugular veins are usually present.
***PowerLecture: Traumatic Reticuloperitonitis
The majority of abortions in cattle infected with Neospora occur in the early second trimester. You have diagnosed neospora abortion on a California dairy and the owner asks you where it comes from?
- Dogs (and coyotes) are the definitive hosts of Neospora caninum
- Cats defecate in the feed and spread the oocysts.
- The disease is venereally transmitted, so all bulls must be tested.
- Pigeons are the source. Shoot and trap all pigeons.
Answer: Dogs (and coyotes) are the definitive hosts of Neospora caninum
Explanation
Neospora abortions usually occur around 4-6 months, but can occur throughout gestation. Calves with neurologic deficits may also result. Dogs ingest infected tissues from fetus or placenta and pass oocysts in feces, which are ingested by cows.
Other causes of abortion tend to occur later in gestation (such as Brucella, Listeria, and leptospirosis). A confirmed diagnosis of N caninum is based on histologic lesions which are found in the brain (and also other organs) and consist of scattered foci of nonsuppurative cellular infiltrates with occasional foci of necrosis.
A 5 month-old Angus calf in a beef herd in northern California has died and another is sick with lethargy and coughing. The herd owner has also seen stiff calves that had difficulty walking and died shortly after being observed. You perform a post-mortem on the dead animal and find pale areas and fibrosis in the cardiac muscles (see image); therefore, a diagnosis of white muscle disease is made. You plan to take blood samples to test for what?
- Clostridial infection of the heart
- Genetic trait linked to myocardiopathy in calves
- Selenium deficiency
- Copper deficiency
- Vitamin A deficiency
Answer: Selenium deficiency
Explanation
Nutritional myodegeneration (white muscle disease) is associated with low dietary selenium levels and compounded by low dietary vitamin E. Unsupplemented cattle grazing soils of volcanic origin are at high risk, and calves born in these herds may show skeletal or cardiac muscle syndromes. Measurement of whole blood selenium in 10 animals will indicate if the herd needs supplementation with selenium.
A 2-year old Brown Swiss with an abomasal torsion is likely to have which electrolyte abnormalities?
- Hyperglycemia, hypochloremia, and hyperkalemia
- Hyperchloremia, hypokalemia and metabolic acidosis
- Paradoxic aciduria, hypochloremia, and hyperkalemia
- Hyperkalemia, hypocalcemia, and metabolic alkalosis
- Hypochloremia, metabolic alkalosis, and hypokalemia
Answer: Hypochloremia, metabolic alkalosis, and hypokalemia
Explanation
The correct answer is hypochloremia, metabolic alkalosis, and hypokalemia. As a result of torsion, affected animals sequester HCl in the abomasum, get hypochloremia and metabolic alkalosis. Additionally, animals become dehydrated and try to maintain adequate blood pressure by conserving sodium through renal mechanisms. Because there is an alkalosis, potassium is sequestered even more than usual in cells leading to hypokalemia. Normally the kidney excretes some potassium because of the need to maintain an equal number of anions and cations in the urine. But when there is insufficient potassium available, in order to reabsorb sodium to maintain blood pressure, hydrogen ions are excreted rather than potassium. This results in acidic urine at the same time as metabolic alkalosis, a condition known as paradoxic aciduria.
It is summer in the hills of coastal California. During spring and early summer, cattle in the area were eating the plant shown in the photo, before other forage was available. Which of the following disorders might occur in cattle which ate a large amount of the plant shown?
- Cardiac arrhythmia
- Bone marrow suppression
- Liver failure
- CNS signs
- Cyanide toxicosis
Answer: Bone marrow suppression
Explanation
The plant is bracken fern and it contains a toxic glycoside (ptaquiloside) plus thiaminase. In cattle, chronic bracken fern ingestion (consumption of the animal’s body weight over several months) can result in bone marrow suppression, as well as alkylation of DNA leading to tumors. The problem will manifest as hemorrhages, hematuria, and/or cancers in the bladder or other organs. The bone marrow suppression leads to anemia and neutropenia.
The thiaminase seems to affect horses more than cattle. Horses develop thiamine deficiency manifested as weight loss, ataxia, lethargy, tremors, recumbency, and death.
Regarding normal reproductive physiology, the cow differs from the sow, the mare, the ewe, and the nanny/doe in which of the following ways?
- Only the cow is normally in estrus for fewer than 5 days
- Only the cow is a seasonal ovulator
- Only the cow has an epithelio-chorial placenta
- Only the cow ovulates after the end of estrus
- Only the cow normally ovulates a single oocyte per cycle
- Only the cow does not have an epithelio-chorial placenta
Answer: Only the cow ovulates after the end of estrus
Explanation
An unusual feature of bovine reproductive physiology is the fact that the cow ovulates after she goes “out” of estrus. The practical implication of this is that one can successfully breed by artificial insemination later, relative to estrus.
The mare, the ewe, and the nanny/doe are all seasonal breeders, but generally, the cow is not.
All the animal species listed in the question have an epithelio-chorial placenta.
Although twin births do occur in a minority of cows, the cow normally ovulates a single oocyte per cycle, as does the mare. Sheep and goats have been selected for fecundity, with the result that multiple ovulations/cycle are the rule, rather than the exception. Litter-bearing pigs ovulate large numbers of oocytes per estrous cycle.
The sheep and goat are in estrus for only 1.5-3 days; the pig is similar. Only the mare, of the species listed, is physiologically in estrus for 5 days or more.
There are 5 dead cows and 3 dead birds next to a pond. The cows have no other medical history. What is your most likely diagnosis?
- Selenium toxicity
- Moldy sweet potato toxicity
- Bracken fern poisoning
- Blue green algae toxicity
- Sudan grass
Answer: Blue green algae toxicity
Explanation
The correct answer is blue green algae toxicity. The fact that they died right next to the pond and the species affected are key factors. Unfortunately, vague presentations are likely to be common on board examinations.
Any living animals would have miosis, ptyalism, bradycardia, and diarrhea as potential clinical signs. The algae produces toxins that are absorbed through mucous membranes and cause a post-synaptic depolarizing block.
Affected animals can die within minutes of drinking the water. As little as 1.5L can kill a cow.
You have diagnosed interdigital necrobacillosis (infectious footrot) in a herd of 300 female beef cattle. It is a rainy summer, and the animals have been confined for artificial insemination in muddy conditions. In addition to treating the obviously lame cattle with oxytetracycline, which of the following recommendations should be made to effectively aid in controlling and preventing the spread of this problem?
- Spray the entire pasture with 2% copper sulfate to eradicate the organism
- Vaccinate herd against Dichelobacter nodosus
- Test all animals and remove Fusobacterium necrophorum carriers
- Put several tons of crushed stones in one area for the cattle to stand on
- Either disperse the group or provide a dry area on which to stand
Answer: Either disperse the group or provide a dry area on which to stand
Explanation
The high density of animals, wet muddy conditions, combined with interdigital trauma from rocks, can be the major culprits. Break that cycle if possible.
Bovine spongiform encephalopathy (BSE or mad cow disease) is not only a health concern for the management of cattle but also has potential public health implications if bovine nervous tissue from infected cows is consumed by humans. BSE has been implicated in a condition that mimics which of the following human diseases?
- Charcot-Marie-Tooth disease
- Churg-Strauss syndrome
- Cockayne syndrome
- Crigler-Najjar syndrome
- Creutzfeldt-Jakob disease
- Crohn’s disease
Answer: Creutzfeldt-Jakob disease
Explanation
BSE is a transmissible spongiform encephalopathy suspected to be caused by a prion.
True Creutzfeldt-Jakob disease (CJD) is a rare disorder that can occur due to a genetic mutation or may occur sporadically. Patients may experience psychiatric symptoms such as depression or a schizophrenia-like psychosis. Unusual sensory symptoms may also occur. Neurological signs progress to difficulty walking and involuntary movements, and, by the time of death, patients become completely immobile and mute.
Variant Creutzfeldt-Jakob disease (vCJD) typically affects younger people and has been strongly linked to exposure, probably through food, to cattle BSE.
You DO NOT need to know about the other human diseases listed here but for your information:
Crohn’s disease is a form of inflammatory bowel disease involving chronic inflammation of any part of the gastrointestinal tract.
Crigler-Najjar syndrome is a rare autosomal recessive disorder of bilirubin metabolism.
Churg-Strauss syndrome is a type of systemic vasculitis.
Charcot-Marie-Tooth disease refers to a group of disorders, usually passed on genetically that are from disorders of myelin or nerves and cause weakness.
Cockayne syndrome is an inherited disorder of DNA repair that causes individuals to be sensitive to ultraviolet light.
You are examining a group of 20 yearling beef heifers in a late summer in Alberta, Canada that has been cooler and wetter than normal. The heifers have been experiencing poor growth and diarrhea. The farmer reports that the cows have developed a frequent, non-productive cough after exertion in the past week. You examine the cows and find their vital parameters to be within normal limits with the exception of several mildly tachypneic cows. There is no ocular or nasal discharge seen. You auscult occasional crackles in many of the cows. Fecal examination reveals Dictyocaulus viviparus L3 in three of six samples. You treat the cows with ivermectin and see cessation of coughing and diarrhea within a few days. Which of the following would be the best way to prevent this problem next year now that there is a known risk?
- Control of snails
- Persistent use of anthelmintics 2 to 3 times during the grazing season
- Control of ticks
- Control of earthworms
- Injectable vaccine administered 4 weeks before the grazing season
Answer: Persistent use of anthelmintics 2 to 3 times during the grazing season
Explanation
Based on the presentation and diagnostic findings, this is a case of Dictyocaulus viviparus, the bovine lungworm and cause of verminous bronchitis. Although the worm is more common in Europe, cases can be seen worldwide including in North America, particularly when weather conditions permit (cooler, moist summers).
Dictyocaulus often affects younger cattle more severely. Signs include cough and frequently tachypnea. The diagnosis is frequently suggested by the seasonal incidence although confirmation with fecal examination (Baermann) is important to achieve a definitive diagnosis. Treatment with an anthelmintic of clinically affected animals is usually effective.
Dictyocaulus has a direct life cycle and does not require a snail, earthworm, or tick for transmission. There are 2 main methods of prevention. A strategic anthelmintic program entails administration of an anthelmintic such as ivermectin at 3, 8, and 13 weeks post-turnout. There are approximately 28 days of residual activity against lungworm. Vaccination is used in some areas (mainly Europe) and involves an attenuated oral vaccine of 1,000 irradiated L3 Dictyocaulus viviparous at 6 and 2 weeks pre-turnout.
The image shows a radiograph of a valuable three-week old dairy calf which is very lame. What is the correct diagnosis?
- Arthritis
- Fractured distal third metacarpal
- Osteosarcoma
- Fescue foot
- Septic arthritis and osteomyelitis
Answer: Septic arthritis and osteomyelitis
Explanation
The destructive lesions in both joint and bone in an animal this age means infectious process. This needs to be cultured, vigorously lavaged or surgically opened and flushed, followed by aggressive systemic antimicrobial drug therapy with appropriate drugs.
Yellow arrows: There is severe soft tissue swelling circumferentially
Red circle: Severe lysis of the proximal interphalangeal joint of the lateral digit
Blue arrows: Marked osseous proliferation.
Radiographs provided by Adrien Hespel, DVM, MS, DACVR and University of Tennessee College of Veterinary
Medicine
Recently, there has been an outbreak of several cows with an acute onset of ataxia, nystagmus, circling, strabismus, and depression followed by strange behavior, vocalization, convulsions, and death in just two days. A few cows appear to be initially less severely affected and have intense pruritus and alopecia which is then followed by similar clinical signs as above. The only recent change in environment is the acquisition of fifty pigs that are housed close by. What is the most likely diagnosis?
- Pseudorabies
- Rabies
- Polioencephalomalacia
- Salt poisoning
- Hypomagnesemia
Answer: Pseudorabies
Explanation
The correct answer is pseudorabies. This question is kind of tough because all the choices are great differentials.
The key here is the history of introducing new pigs and the pruritus with alopecia. Pigs are the primary host of pseudorabies and are usually asymptomatic. Some of these pigs were probably infected and being in close proximity somehow the disease has been introduced to the cattle. Even though there is an outbreak going on, it is probably not going to be self-perpetuating among the cattle since they don’t shed virus for long periods of time. In cases that are not as peracute to acute the first clinical signs are often paresthesia hence the name “Mad Itch”. However, you must be careful because sites of rabies virus inoculation are also pruritic and result in alopecia from scratching. Unfortunately, there is no treatment and most affected animals die. The best thing to do is remove the pigs.
It is March in the foothills, the grass is 2 inches high, and the oak trees are in early leaf stage. The calves are 4-5 months old, grazing alongside their dams. There are some 12,000 calves scattered around the county. A huge sudden spring snowstorm deposits 10 inches of wet snow, completely covering the grass and causing many oak branches to break and fall to the ground. Ranchers remember that when this last happened 20 years ago, many of their calves died or became very sick from eating nothing but oak leaves and buds for a week. What can you recommend to them now to avoid a repeat of such a scenario?
- Administer IV fluids to all calves to flush out the oak toxins
- Quickly spread hay out in the hills where the calves can eat it
- No action is necessary, the calves will simply suckle their dams and avoid the oak
- Catch calves and administer calcium hydroxide to each one daily
- Apply for disaster aid
Answer: Quickly spread hay out in the hills where the calves can eat it
Explanation
The best way to prevent oak (Quercus) toxicity is to allow the animals to fill up on hay, since the grass is covered by snow. None of the other solutions are practical (or possible).
Oak tannins are hydrolyzed in the rumen to toxic gallic acid, pyrogallol. Cattle can normally eat some oak and handle the tannins, but when the diet consists of mainly oak the high levels of tannins disrupt the Gl mucosa, and the gallic acid and pyrogallols destroy renal tubules. Some hydrolyzed tannins are absorbed and bound to plasma proteins and endothelial proteins, leading to vascular damage and fluid and blood loss from vessels, resulting in edema.
Ruminants are more susceptible than horses because of the hydrolysis of gallotannins in the rumen.
