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.
Pseudorabies in Pigs: Quick Reference for BCSE Test Preparation
Etiology: Pseudorabies is caused by a DNA herpesvirus, primarily affecting swine but can incidentally infect other species.
Epidemiology: Transmitted through direct (nose-to-nose, fecal-oral) and indirect (aerosolized virus) contact. The virus survives in various environments.
Clinical Findings:
• Young piglets: CNS disease, high mortality.
• Weaned pigs: Respiratory disease.
• General signs: Fever, anorexia, weight loss, sneezing, dyspnea.
• Nonporcine species: Sudden death, pruritus, CNS signs.
Pathogenesis: The virus replicates in nasal, pharyngeal, or tonsillar epithelium, spreading to the brain via lymphatics and nervous tissue.
Lesions: Gross lesions are often undetectable. Microscopically, nonsuppurative meningoencephalitis and neuronal necrosis are seen.
Diagnosis: Based on CNS signs and reproductive failure in piglets, confirmed by serology, PCR, and virus isolation.
Treatment and Control: No specific treatment. Vaccination is highly effective and vital for control. Eradication strategies include whole-herd depopulation and offspring segregation.
Key Points: Pseudorabies is reportable. The USA’s commercial pig industry is pseudorabies-free due to effective vaccination programs.
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.
Several 2- to 4-year old cows in a herd have been losing weight and suffering with chronic watery diarrhea for the past eight months. Which of the following is a good differential?
- Rotavirus
- Pasteurella multocida
- Enteropathogenic E. coli
- Mycobacterium avium subsp paratuberculosis
- Trueperella pyogenes (formerly Arcanobacterium pyogenes)
Answer: Mycobacterium avium subsp paratuberculosis
Explanation
The correct answer is Mycobacterium avium paratuberculosis (Johne’s disease). This disease is known to affect cattle, goats, and sheep, as well as many species of exotic hoofstock.
Infection usually occurs when they are young, but clinical signs do not show up until the animals are stressed. Clinical signs are essentially diarrhea and weight loss due to hypoalbulinemia. The other choices are poor in that they don’t result in a herd problem of weight loss and diarrhea in adult cattle.
For the PowerLecture” on this topic, view
• Paratuberculosis - Johne’s Disease (8:50).
What is the normal presentation and position at birth of a calf?
- Anterior presentation, ventro-sacral position, front limbs extended
- Anterior presentation, dorso-sacral position, front limbs flexed at shoulder
- Posterior presentation, dorso-sacral position, hind limbs flexed
- Anterior presentation, dorso-sacral position, front limbs extended
Answer: Anterior presentation, dorso-sacral position, front limbs extended
Explanation
The correct answer is anterior presentation, dorso-sacral position, and front limbs and head/neck extended (posture). Anterior presentation describes how the head is exiting the birth canal first. Dorso-sacral position signifies that the dorsum of the fetus is against the sacrum of the cow. Front limbs and head extended is the normal posture of a calf at birth, and implies that the front limbs will be visible first, followed shortly by the nose. This is the normal presentation, position, and posture.
You are called one summer day by a local dairy because they have 40 cows down and unable to get up this morning. Several others are weak and staggering. The owner reports that the affected cows are in all stages of lactation. You rush to the farm and examine several cows. They have normal TPRs, but are profoundly weak. When you pull out the tongue to examine the mouth, the tongue stays out (see image). Masseter muscle strength also seems weak. The cows have poor rumen motility and refuse food. The eyes are dilated and pupillary light responses are poor. The ears droop and tail tone is weak. Which disease best fits these clinical signs?
- Listeriosis
- Organophosphate toxicity
- Botulism
- Milk fever
- Anaplasmosis
Answer: Botulism
Explanation
Also known as forage poisoning, botulism usually occurs in groups of animals fed either haylage improperly stored in plastic bags or feed contaminated by an animal carcass and then mixed into the total mixed ration.
A 3-week old Holstein calf was born unable to bear weight on its pelvic limbs and was often observed dog-sitting. Now, 3 weeks old, the calf is unable to bear weight on the right hindleg (see image). Radiographs show no bony abnormalities. Which of the following would likely prevent this problem in the future?
- Delivery by Cesarean section
- Supplement cows with thiamine
- Vaccinate cows against bovine viral diarrhea virus
- Remove all lupine from the pasture
Answer: Delivery by Cesarean section
Explanation
The description and appearance are most consistent with femoral nerve paralysis. This typically occurs due to excessive traction of oversized calves in anterior longitudinal presentation during calving. Rotation of the calf by 45 degrees into a diagonal orientation to align the widest dimension of the calf’s hips with the widest dimension of the maternal pelvis may assist delivery in some cases. This problem could have been avoided by Caesarean.
The femoral nerve supplies the quadriceps femoris muscle and injury results in rapid and severe atrophy and the inability to extend the stifle joint and bear weight on that leg. Bilateral femoral paralysis results in the inability to stand. Fractures of long bones following dystocia are rare but can occur. Such fractures can be detected by careful clinical examination and radiography.
After you make a diagnosis of Hypoderma lineatum in a herd of beef cattle, the owner asks how the warble got there and what its life cycle. You explain the difference between Hypoderma lineatum and Hypoderma bovis. What is the difference in life cycle between the two?
- L3 larvae of H. bovis migrate to the esophagus, while L3 larvae of H. lineatum migrate to the epidural fat of the spinal cord
- Ll larvae of H. lineatum migrate to the esophagus while L1 larvae of H. bovis migrate to the epidural fat of the spinal cord
- L3 larvae of H. lineatum migrate to the esophagus, while L3 larvae of H. bovis migrate to the epidural fat of the spinal cord
- L1 larvae of H. bovis migrate to the esophagus, while L1 larvae of H. lineatum migrate to the epidural fat of the spinal cord
Answer: L1 larvae of H. lineatum migrate to the esophagus while L1 larvae of H. bovis migrate to the epidural fat of the spinal cord
Explanation
L3 larvae of both H. lineatum and H. bovis are on the subcutaneous tissue of the back (L2 larvae migrated there and then molted to L3 larvae), where they drill an air hole and then grow before falling out on to the ground, pupating for 1 to 3 months before becoming a short-lived fly.
A 6-month old calf presents with a head tilt towards the right side and spontaneous horizontal nystagmus with the fast phase directed towards the left side. Ventral strabismus (eye drop) is present on the right side. There is drooping of the right upper eyelid and drooping of the right ear (see image). Which of the following is the best list of differential diagnoses?
- Otitis media/interna, middle ear trauma, listeriosis
- Bluetongue, bovine viral diarrhea virus, bovine spongiform encephalopathy
- Polioencephalomalacia, congenital brain tumor, thromboembolic meningoencephalitis
- Rabies, pseudorabies, cerebellar hypoplasia
Answer: Otitis media/interna, middle ear trauma, listeriosis
Explanation
The calf’s signs are most consistent with dysfunction of the peripheral vestibular system (although one cannot rule out central vestibular) and facial nerve dysfunction. Middle/inner ear infection or trauma are likely and listeria is a reasonable differential as well. Most of the other choices listed are not typically associated with vestibular signs as described in this case.
Which group of drugs cannot legally be used in an extra label manner in the United States on food producing cattle?
- neomycin, gentamicin, sulfamethazine, estradiol, sodium iodide, prostaglandins
- tetracycline, penicillin, florenicol, sulfas, ampicillin, estradiol, prostaglandins
- diethyl stilbestrol, chloramphenicol, nitroimidazoles, clenbuterol, fluoroquinolones, vancomycin, nitrofurans
- monensin, ivermectin, fenbendazole, moxidectin, lasalocid, decoquinate
Answer: diethyl stilbestrol, chloramphenicol, nitroimidazoles, clenbuterol, fluoroquinolones, vancomycin,
nitrofurans
Explanation
In addition, it is not permitted to use phenylbutazone and most sulfas in adult dairy cattle. The rules are under the FDA and part of AMDUCA, the Animal Medicinal Drug Use Clarification Act.
It is November and one of a group of 6 to 7-month old calves that entered a feedlot 50 days ago is sick. He has been observed coughing and open-mouth breathing with his head extended, and has a nasal discharge. You examine him and find his vitals to be T=105F 40.6 C, RR=70 (27-36 breaths/min), HR= 100 (60-70 beats/min). His breath is necrotic-smelling, and his larynx is swollen and painful on palpation (see image). There is inspiratory dyspnea and stertor. Based on the history and clinical signs you diagnose necrotic laryngitis (calf diphtheria), believed to be initiated by Histophilus somni, after which Fusobacterium necrophorum proliferates where the mucosa is damaged. This causes necrosis of the laryngeal cartilages. Knowing that the disease is commonly fatal, you elect to treat aggressively. Which of the following would be the best course of therapy?
- Dexamethasone
- Chloramphenicol
- IV Tetracycline followed by SC long acting tetracycline, plus NSAIDS
- Topical sprays containing iodine
- NSAIDS
Answer: IV Tetracycline followed by SC long acting tetracycline, plus NSAIDS
Explanation
The laryngeal cartilages (particularly the arytenoids) can become necrotic (see image), toxemia and bacteremia can develop, and death can ensue. Treatment must be aggressive. Start with a high blood level by giving IV tetracycline, then follow up with long acting tetracycline. Repeat as needed. Penicillin is also a good choice against Fusobacterium necrophorum, but it is more difficult to achieve high levels long-term using penicillin than it is with tetracycline. When edema, inflammation, and dyspnea are very severe, a tracheostomy may be needed, and a dose of corticosteroids may help shrink the swollen larynx. NSAIDS are also indicated. Good nursing care is also essential to recovery.
Chloramphenicol cannot legally be used in animals intended for meat or milk in the USA. Dexamethasone could be used in conjunction with antimicrobials but not alone against Calf Diphtheria. Sprays would not cure this calf.
A 4 month old Holstein heifer has a loud cough, tachypnea, diarrhea, and ill thrift of 8 days duration. However, there are no signs of sepsis, depression, or loss of appetite. On physical exam, you could hear crackles and wheezes over the lung fields and a harsh bronchial tone cranioventrally. Given this presentation what is the most likely diagnosis?
- Aspiration pneumonia
- Shipping Fever
- Enzootic pneumonia
- Moldy sweet potato poisoning
Answer: Enzootic pneumonia
Explanation
The correct answer is enzootic pneumonia. This disease is multifactorial but is mainly a result of poor housing and environment (poor sanitation and ventilation). Calves with enzootic pneumonia will have cranioventral consolidation and many times they have diarrhea as a result of being infected with Eimeria bovis (like this one).
Shipping fever (fibrinous pleuropneumonia) will most likely present with more systemic signs, which is key in differentiating the two diseases. Aspiration pneumonia will probably not result in diffuse lung pathology without also causing systemic signs. Moldy sweet potato poisoning is a good differential and will result in respiratory disease followed by death, but there was no history of exposure here. However, these animals will typically present with more acute respiratory distress and will probably not survive for 8 days, as death usually ensues 2-5 days after exposure. The principal toxin is ipomeanol which is produced by sweet potatoes infected with Fusarium javanicum or F. solani. Ipomeanol will destroy clara cells and type I pneumocytes.
You examine a 3-year old Holstein dairy cow on a small farm that pastures the animals every day in the summer. This cow, purchased as a 2-year old springer, was producing 80 lbs of milk per day in the 4th month of her lactation, but she suddenly lost a tremendous amount of weight in the last month (see photo) and developed watery green diarrhea. She has a normal TPR but is weak and rail thin. What should you tell the owner that you suspect the cow has?
- Grain overload (lactic acidosis)
- Fatty liver
- Paratuberculosis (Johne’s disease)
- Ostertagiasis
- Salmonellosis
Answer: Paratuberculosis (Johne’s disease)
Explanation
Caused by Mycobacterium avium ssp paratuberculosis, this infectious disease causes a granulomatous ileitis and colitis. Diarrhea usually results. The affected bowel dumps albumin into the lumen, and the cow can lose weight extremely rapidly, although this is highly variable. Confirmatory tests such as a serum ELISA should be done.
***PowerLecture: Paratuberculosis - Johne’s Disease
A recently freshened 4-year old Guernsey with a body condition score of 4/5 presents for decreased milk production, anorexia, and depression. On physical exam, she has a mild fever and is ketotic. No pings were auscultated during the physical exam and a rectal exam was unremarkable. What is the most likely diagnosis?
- Fatty liver syndrome
- Right displaced abomasum
- Pyrrolizidine alkaloid toxicity
- Oleander toxicity
Answer: Fatty liver syndrome
Explanation
The correct answer is fatty liver syndrome. Fat cows are more predisposed to fatty-liver syndrome when they encounter a negative energy balance. Shortly after parturition, their energy needs increase dramatically with lactation. Clinical signs are vague so you must be able to reach the answer by paying attention to the signalment. Further, an RDA will present with much more systemic signs and you will be able to hear a ping.
PA toxicity and oleander toxicity are possible but less likely given the signalment and clinical signs.
Remember, oleander is cardiotoxic and causes arrhythmias and PAs will cause chronic damage to the liver.
***PowerLecture: Hepatic Disorders
A 3-year old Holstein dairy cow, 3 weeks post partum, is presented with the complaint that she has dropped in milk production over the last several days. You perform a physical exam and the only abnormality you note is a large amount of ketone bodies in the milk and urine. You decide to administer glucose IV and insulin SQ. What else should this cow be administered?
- IV calcium gluconate
- IM tetracycline
- IM parathyroid hormone
- SQ bovine somatotropin
- Oral propylene glycol
Answer: Oral propylene glycol
Explanation
The oral propylene glycol will serve as a precursor for glucose production, and will help with the demands of lactation that are causing increased fat mobilization and ketosis. A fourth treatment that is sometimes used is corticosteroids, as they decrease milk production and increase gluconeogenesis.
PowerPage: Ketosis
A beef steer in a feedlot has moderate chronic bloat, and is eating poorly and losing weight (see image). He was treated a month ago for bovine respiratory disease complex with antimicrobials given for 3 days. You examine him and find a temp=104F (100- 102.6F) (40 C), HR=95/min (60-70), RR=64/min (37-36), and the rumen is gas-filled and has only weak motility. When you pass a stomach tube, the gas is readily removed from the rumen. The lung sounds are harsh ventrally on inspiration and expiration, with some crackles and wheezes also auscultable. On percussion, the ventral thorax is dull. The steer coughs several times while being examined. What is your diagnosis?
- Bovine respiratory syncytial virus pneumonia
- Frothy bloat
- Type 2 vagal indigestion
- Free gas bloat secondary to chronic bronchopneumonia
- Acute bovine pulmonary edema and emphysema
Answer: Free gas bloat secondary to chronic bronchopneumonia
Explanation
Cattle have relatively poor collateral ventilation (as compared to a horse for example) so they tend to get pulmonary consolidation with chronic bronchopneumonia. The inflammation and enlarged lymph nodes associated with chronic infection of the lungs can affect the vagus nerve as it passes through the chest, resulting in type 1 vagal indigestion, or free gas bloat.
Type 2 vagal indigestion is failure of omasal transport and appears as an enlarged fluid-filled rumen. It is most often associated with traumatic reticuloperitonitis. Bovine respiratory syncytial virus pneumonia tends to occur in younger calves and be much more acute and with different auscultation findings than described here. The signs and physical exam do not fit either frothy bloat or acute bovine pulmonary emphysema.
It is the middle of winter and this adult Holstein cow in the picture has just presented after developing neurologic signs including ataxia, head-pressing, nystagmus, and star-gazing. There were no significant clinical exam findings besides the neurologic signs described. The owner was questioned about the housing situation this cow was in because this cow is representing 7 other individuals who are similarly affected. The owner said that nothing has changed in the diet and they are fed a complete mixed ration. Additionally, they are provided water with automatic water feeders. Initial blood work is as follows: Sodium 164 mEq/L (normal 132-152), Chloride 115 mEq/L (normal 97-111), Potassium 4.6 mEq/L (normal 3.9-5.8), Calcium 11.9 mg/dl (normal 9.7-12.4), Glucose 78mg/dl (normal 45-75), and Protein 7.9mg/dl (6.7-7.46). Which of the following is the most likely diagnosis?
- Salt poisoning
- Blue-green algae toxicosis
- Lead poisoning
- Leukoencephalomalacia
Answer: Salt poisoning
Explanation
The correct answer is salt poisoning. Notice the markedly elevated blood sodium level. A sodium value that high is diagnostic for salt poisoning. If for some reason you are still not sure, you could perform a CSF tap and check the sodium levels and be completely certain. What probably happened to these animals is that the water pipes froze (occurs in northern US with cold winters). As a result, the cows were deprived of water for a certain period of time. During that time, their bodies began to accumulate sodium in the cells of the brain and produce these intracellular proteins to draw water in and maintain normal function. The cows then drink lots of water at the first chance they get, and the hyperosmolar environment in the brain causes water to rush into the cells and destroy them. Ingestion of blue-green algae results in a peracute intoxication which usually results in convulsions, ataxia, bloody diarrhea, and death. Leukoencephalomalacia is a disease which affects horses as a result of ingesting corn infested by the fungus Fusarium moniliforme. Lead poisoning is less likely because the history, clinical signs, and findings are not consistent with exposure to lead.
Maple syrup urine disease is a genetic disorder associated with spongiform changes in the brain and caused by a deficiency of this enzyme in Hereford and polled Shorthorn calves. It usually shows up at 2 to 3 days of age. Which of the following enzymes is the correct one?
- Pyruvate kinase
- Carnitine acyl translocase
- Branched-chain ketoacid decarboxylase
- Acetyl-CoA carboxylase
Answer: Branched-chain ketoacid decarboxylase
Explanation
The correct answer is branched-chain ketoacid decarboxylase, which will cause accumulation of 2-keto-3-methylvaleric, 2-ketoisocaproic, and 2-isovaleric acids along with their precursors isoleucine, leucine, and valine.
These are excreted in the urine and result in a burnt maple syrup smell (hence the name of the disease).
This hereditary disease causes an encephalopathy. Acetyl-CoA carboxylase turns acetyl-CoA into malonyl CoA in fatty acid synthesis. Carnitine acyl translocase helps bring fatty acids across the inner mitochondrial membrane for degradation. Pyruvate kinase turns phosphoenol-pyruvate into pyruvate in the glycolysis pathway.
In paradoxic aciduria in the cow, which ion is exchanged for sodium in the renal tubules?
- Chloride
- Bicarbonate
- Hydrogen
- Calcium
- Potassium
Answer: Hydrogen
Explanation
The correct answer is hydrogen. Paradoxic aciduria can commonly occur in cows in situations where HCl trapping occurs in the abomasum such as when there is a torsion. This will lead to a hypochloremia.
Dehydration also occurs and in the process of trying to conserve sodium to maintain blood volume, bicarbonate is retained and the cows become alkalotic. Then the cow’s cells exchange hydrogen from inside the cell and take in potassium to try and return to a normal pH. This results in hypokalemia; the kidney tubules then start using hydrogen (instead of potassium) to exchange for sodium and conserve sodium. This means that they are excreting hydrogen and this is paradoxic aciduria.
***PowerLecture: Vagal Indigestion
A dairy farmer asks you to perform a post mortem exam on a mature Holstein which died suddenly last night. You find the peritoneal cavity full of rumen contents and a perforated ulcer through a rumen pillar (see photo showing rumen mucosa), as well as other ulcers in the rumen mucosa. Based on these findings, what is the correct diagnosis?
- The ulcer inducing bacteria Helicobacter pylori
- Rumen acidosis with ulceration
- Chronic stress induced ulcers
- Mycotic rumenitis from moldy feed components
- Acid reflux from the abomasum into the rumen
Answer: Rumen acidosis with ulceration
Explanation
Feeding high concentrate levels or suddenly changing the amount of concentrate fed can result in a drop in rumen pH below 5.5, ulcers and even perforation. Introducing concentrate slowly and feeding buffers such as sodium bicarbonate can help minimize these problems in high-producing dairy cattle.
Several 6-month old calves in a herd have been losing weight and showing signs of diarrhea. As part of your work up to diagnose the problem in the herd, you perform a McMaster fecal egg count. Which of the following is an appropriate minimum egg count at which you should plan to deworm the calves to promote weight gain?
- 10 eggs per gram of feces
- 1500 eggs per gram of feces
- 700 eggs per gram of feces
- 20 eggs per gram of feces
- 300 eggs per gram of feces
- 100 eggs per gram of feces
Answer: 300 eggs per gram of feces
Explanation
Once you see an egg count between 300-400 per gram, with or without compatible clinical signs, you should consider deworming. That is the level at which weight gains in growing calves will begin to be affected.
A dairyman’s favorite cow was bred by a new bull a few weeks ago and now his cow has pyometra. What agent is most likely responsible for causing the cow’s pyometra?
- Tritrichomonas foetus
- Campylobacter fetus
- Leptospirosis
- Brucellosis
Answer: Tritrichomonas foetus
Explanation
The correct answer is tritrichomonas foetus. This organism is commonly associated with a post-coital pyometra in addition to causing early embryonic death. Campylobacter is a cause of early embryonic death but does not usually result in pyometra. Brucella will result in late term abortion. Leptospirosis is a cause of mid- to late-gestation abortions and not post-coital pyometras.
Based on the figure shown, what is the truest statement about the relationship between serum copper and liver copper levels in the bovine?
- Normal liver copper levels are above 200 ppm
- A serum copper above 1.0 ppm is considered low normal
- When liver copper is below 25 ppm, serum copper will be below 0.5 ppm
- There is no important relationship between liver and serum copper levels
- The serum copper level has to fall dramatically before the liver copper decreases
Answer: When liver copper is below 25 ppm, serum copper will be below 0.5 ppm
Explanation
The liver is the major copper storage organ. Before the serum copper drops, the liver must be depleted of copper stores. Liver biopsy is thus the recommended means to identify the animal’s copper status more sensitively.
In attempting to optimize absorption of antibodies from dairy cow to calf, and prevent failure of passive transfer, which of the following is most important?
- Ingestion of adequate mass of lgG shortly after birth
- Insuring via vaccination that placental transfer of important antibodies occurs before birth
- Allowing the calf to nurse the cow for the first 24 hours after birth
- Ingestion of adequate amount of IgA in colostrum within 2 hours of birth
Answer Ingestion of adequate mass of lgG shortly after birth
Explanation
Immunoglobulin G in the total amount of 150 to 200 grams per dairy calf seems to be optimal. If average dairy cow colostrum contains 35 mg/mL of IgG1, this requires that at least 4 liters of colostrum be ingested.
A local purebred cattle herd has been increasingly affected with papillomas to the point that it is now a problem throughout the herd, and the owner is concerned. Which of the following treatment options would yield the best results?
- Treat herd with acyclovir
- Prepare an autogenous vaccine by isolating some warts from the herd
- Depopulate the herd
- Purchase commercially available vaccine
Answer: Prepare an autogenous vaccine by isolating some warts from the herd
Explanation
The correct answer is to prepare an autogenous vaccine by isolating some warts from the herd. The commercially available vaccine is thought to be effective only against the same strain; therefore, it is not curative in many cases. Treating with acyclovir is not recommended. The least desirable treatment option would be depopulation of the herd. This would potentially be financially devastating.
How many injections and at what spacing is PGF2-alpha given to synchronize a dairy cow?
- 2 injections approximately 11-14 days apart
- 2 injections approximately 5 days apart
- 4 injections approximately 11-14 days apart
- Only one injection is necessary
Answer: 2 injections approximately 11-14 days apart
Explanation
The correct answer is 2 injections approximately 11-14 days apart. This will assure that those that had an immature, unresponsive, corpus luteum during the first shot are synchronized on the second shot. Additionally, those that were synchronized on the first injection will have a corpus luteum that will be responsive to PGF2-alpha in 11-14 days. Giving 4 injections is not necessary. If you give the injections at 5 days apart you run the risk of having CLs that are unresponsive because they are not mature enough and they won’t lyse.
A 6 month old Brown Swiss presents for respiratory distress of 1 day duration. She has a moist, painful cough and a loud inspiratory stridor. On physical exam, it is noticed that the head and neck are extended, there is a swelling around the larynx, and ozena. She also has a temperature of 104.6F (40.3C) and episcleral injection. On palpation of the larynx, a cough is easily elicited along with pain and increased stridor. What is the most likely organism causing this and diagnosis?
- Trueperella pyogenes, abscess of throat
- Papilloma virus, Laryngeal warts
- Actinomyces bovis, lumpy jaw
- Fusobacterium necrophorum, calf diphtheria
Answer: Fusobacterium necrophorum, calf diphtheria
Explanation
The correct answer is Fusobacterium necrophorum (aka calf diphtheria or necrotic laryngitis). Clinical signs are seen between 3-18 months of age. The signs are usually acute, and the animals may die within the week if they are not treated. Actinomyces bovis is the cause of lumpy jaw. Trueperella pyogenes may cause laryngeal abscesses, however affected animals are not febrile and septic. Laryngeal papillomatosis is fairly common in feedlot cattle and is caused by a papovavirus. Clinical signs are usually stertorous respiration and a cough. Again, there are no systemic signs as there are with calf diphtheria.
A farmer who raises valuable registered Holstein cattle calls you in a panic to tell you that he has just mistakenly orally administered a gallon of propylene glycol to a 600kg cow with constipation, thinking it was mineral oil. He asks what toxic effects this could have and what you can do about preventing/minimizing the toxic effects. Of the following choices, what is the correct treatment at this point?
- Calcium gluconate IV
- Urinary acidification using an anionic diet
- Large doses of NSAIDs every 8 hours
- General anesthesia to prevent seizures
- Intravenous and oral fluids to cause diuresis
Answer: Intravenous and oral fluids to cause diuresis
Explanation
This amount of propylene glycol is likely to cause several problems: first the CNS effects of depression and disorientation, next at 12 to 24 hours come cardiovascular and pulmonary signs, along with severe metabolic acidosis. From 24 to 72 hours renal toxicity may predominate due to tubular damage.
The best treatment is diuresis using isotonic sodium containing fluids for the next several days.Since there metabolic acidosis, using sodium bicarbonate and some IV glucose to help maintain blood glucose are also helpful. You can also bind some of it in the rumen by giving activated charcoal immediately, but propylene glycol is poorly bound to charcoal. By three days the propylene glycol and toxic products are usually eliminated.
Daily checks on the serum creatinine can help determine when fluids can safely be stopped.
In humans they might also use a drug called Fomepizole (Antizol) and/or IV ethyl alcohol (600-800 mg/kg IV) and dialysis if needed. Other recommendations include the B vitamins thiamine and pyridoxine.
How many injections and at what spacing is PGF2-alpha given to synchronize a dairy cow?
- 4 injections approximately 11-14 days apart
- Only one injection is necessary
- 2 injections approximately 11-14 days apart
- 2 injections approximately 5 days apart
Answer: 2 injections approximately 11-14 days apart
Explanation
The correct answer is 2 injections approximately 11-14 days apart. This will assure that those that had an immature, unresponsive, corpus luteum during the first shot are synchronized on the second shot.
Additionally, those that were synchronized on the first injection will have a corpus luteum that will be responsive to PGF2-alpha in 11-14 days. Giving 4 injections is not necessary. If you give the injections at 5 days apart you run the risk of having CLs that are unresponsive because they are not mature enough and they won’t lyse.
You arrive at a dairy in Northern California that has several lactating cows that are pale, icteric, and showing lemo globinuria. You perform blood work and se no signs of methemoglobinemia or Heinz bodies, Phosphorus levels range between 1.6 and 2.0 mg/dl. What is your diagnosis?
- Anaplasmosis
- Babesia
- Onion toxicosis
- Copper toxicity
- Postparturient hemoglobinuria
Answer: Postparturient hemoglobinuria
Explanation
The correct answer is postparturient hemoglobinuria. The key to correctly answering this question is to know that phosphorus levels less than 2.0 mg/dl will most likely result in hemolysis. Paying attention to the fact that these cows are lactating should also help you to reach the correct diagnosis. Copper and onion toxicity will both cause methemoglobinemia. Anaplasmosis does not result in hemoglobinuria.
You are called to examine and treat a valuable 3 year old show cow that appeared normal yesterday but has collapsed and is too weak to get up (see photo). You examine her and find T=102F or 38.9 C, HR=130, and RR=42. Her heart is pounding very loudly. The mucous membranes of her eyes, mouth and vulva are all very pale. You diagnose an acutely bleeding abomasal ulcer. What is the most important treatment?
- 40 liters balanced electrolytes orally
- 40 liters of saline IV
- 20 liters of 1.3% sodium bicarbonate IV
- 4 to 8 liters of fresh whole blood IV
- 4 liters of commercial plasma IV plus vitamin K
Answer: 4 to 8 liters of fresh whole blood IV
In the case of an acute blood loss such as this, the most important treatment is whole blood.
Other sodium-containing fluids may be beneficial while the blood is being collected if this will not result in losing time in getting the whole blood into this cow. In most cases the single blood transfusion results in recovery.
After about 24 hours the cow will exhibit melena as the digested blood reaches the rectum.
An owner wishes to abort a fetus in his cow which may be pregnant because it was bred by the neighbor’s bull that had jumped over the fence 1 week previously. What is the best way to induce abortion?
- Give PGF2-alpha
- Give dexamethasone
- Give oxytocin
- Give estrogen
Answer: Give PGF2-alpha
Explanation
The correct answer is to give PGF2-alpha.
Remember that PGF 2-alpha will lyse the corpus luteum. If it has been less than 4 months (which it likely has) the corpus luteum is still the main contributor of progesterone and destroying it will induce abortion. After 4 months, the placenta helps contribute progesterone for a few months.
However, during the last month of pregnancy the placenta does not contribute significantly to progesterone production. Therefore, just giving PGF2-alpha during the last month will also cause abortion. To induce abortion anywhere in between you will need PGF 2-alpha and dexamethasone.
Additionally, to induce parturition during the last month of pregnancy, dexamethasone can be used because it will mimic the fetal rise of cortisol, followed by parturition, including production of fetal pulmonary surfactant.
A herdsman is concerned about Johne’s disease affecting his herd. He comes to you and asks what the treatments of choice for the affected cattle are. What is your response?
- Treat with penicillin
- Treat with chloramphenicol
- Treat with tetracycline
- Cull all cattle that test positive
- Treat with rifampin
Answer: Cull all cattle that test positive
Explanation
The correct answer is to cull all cattle that test positive. Johne’s disease in cattle is caused by Mycobacterium avium subsp paratuberculosis affecting the small and large intestine. Clinical signs include emaciation, wasting, and edema, with variable diarrhea. Diagnosis is by serology and identification of the acid fast bacteria. There is no effective treatment for the disease.
Positive animals must be culled from the herd.
***PowerLecture: Paratuberculosis - Johne’s Disease m
In mid-autumn you attend a group of 64 housed beef cattle aged 9-12 months, purchased from numerous markets over the previous 3 weeks. Frequent coughing has been heard in the group over the past week. The farmer has selected two inappetant animals with purulent ocular and nasal discharge for veterinary examination. Clinical examination reveals pyrexia of 105.4F and 106.OF (40.8 to 41.1 C). The respiratory rate is increased and auscultation of the chest reveals referred upper respiratory tract noise. Visual inspection of the remainder of the group reveals a number of cattle with mucopurulent ocular and nasal discharge and tachypnea, as well as several cows who have a swollen vulva with erosions and ulcers. Six animals are selected and examined, all of which have a rectal temperature > 105F (40.6 C). Which of the following recommendations is best?
- Report this outbreak to the state veterinarian
- Vaccinate all cattle with intranasal vaccine against the virus and treat sick animals with intramuscular procaine penicillin for 3 days
- Treat all animals with ivermectin now and repeat in 3 weeks
- Treat all animals with oxytetracycline for 7 days
Answer: Vaccinate all cattle with intranasal vaccine against the virus and treat sick animals with intramuscular procaine penicillin for 3 days
Explanation
The clinical course of this case is strongly suggestive of infectious bovine rhinotracheitis (IBR), caused by Bovine Herpesvirus-1. Antimicrobial therapy is indicated to prevent or treat secondary bacterial infection. Both intramuscular and intranasal vaccines are available and effective (although the intramuscular vaccine may cause abortion in pregnant cows). In the future, breeding and replacement animals should be immunized at 6-8 months of age. before breeding, and then yearly. Feeder calves should be immunized 2-3 weeks prior to entering the feedlot.
A 3 week old Guernsey calf presents with fever, anorexia, and depression. The calf had diarrhea and the owner had tube fed it several times a few days ago. On physical exam, you auscultate harsh lung sounds and crackles cranioventrally on both sides of the chest. Which of these is a likely differential?
- Fibrinous pleuropneumonia
- Pneumothorax
- Aspiration pneumonia
- Fog fever
Answer: Aspiration Pneumonia
Explanation
The correct answer is aspiration pneumonia. Cranioventral lung disease is the classical finding with aspiration pneumonia. If you think about it, you realize that if an animal inhales particulate matter, gravity will influence its path and thus there will be cranioventral involvement.
Potential causes of aspiration pneumonia in calves include leaking nipples from milk bottles, mineral oil drenches, pharyngeal paralysis (due to white muscle disease), gastric reflux, improper intubation, and hypoglycemia.
A pneumothorax results in no audible lung sounds dorsally.
Fibrinous pleuropneumonia is a good differential, however the clinical signs will be more severe and lung pathology will be more diffuse. For example, you will be able to hear crackles and wheezes in all areas, appreciate a soft cough, see nasal discharge, and at times, pleural rubs may be audible if there is pleural effusion or a septic pleuritis.
Fog fever is a respiratory disease of adult cows that results when they suddenly consume lots of lush pasture. At this point, the plants are high in tryptophan which is subsequently metabolized in the rumen to 3-methyl indole (toxic to the lungs).
Pulmonary emphysema, edema, and Interstitial Pneumonia in Cattle
Pulmonary Emphysema, Edema, and Interstitial Pneumonia in Cattle
Definitions and Causative Agents:
• Acute Bovine Pulmonary Emphysema and Edema (ABPEE): Also known as “fog fever”, caused by metabolites of L-tryptophan in lush pasture. • Pathogenesis: L-tryptophan is converted by ruminal microorganisms to 3-methylindole, which is pneumotoxic.
Clinical Changes and Symptoms:
• Symptoms: Mild to severe dyspnea, tachypnea, hyperpnea, mouth breathing, drooling, expiratory grunt, minimal coughing. • Lesions: Pulmonary edema, emphysema, alveolar epithelial hyperplasia, hyaline membrane formation.
Diagnosis:
• Assessment: History of pasture change, clinical signs, necropsy findings. • Histopathology: Congestion, alveolar edema, epithelial hyperplasia.
Treatment:
• No effective treatment: Manage affected animals with caution to prevent further stress and possible sudden death.
Prevention:
• Pasture Management: Gradual introduction to lush pastures, use of hay before grazing, strip grazing, grazing with less susceptible animals first. • Medications: Monensin or lasalocid to inhibit bacteria converting L-tryptophan to 3-methylindole.
For detailed information, visit the Merck Veterinary Manual - Pulmonary Emphysema, Edema, and Interstitial Pneumonia in Cattle.
A 4 year-old dairy cow that is 2 weeks post-partum is experiencing low milk production and appears to not be eating well, spending less time at the feed bunk than herd mates. She has also been heard grinding her teeth, swishing her tail, and repeatedly lying down and getting up after a short time. You examine her and find a fever of 105F (40.6 C), HR=90/min, rumen quite empty, rumen motility poor, and a gaunt abdomen. On rectal exam the left kidney appears to be enlarged and painful; no other abnormalities are noted. You take a urine sample and note blood and pus in it. What is the most likely diagnosis?
- Urolithiasis
- Metritis
- Pyelonephritis
- Renal tumor
- Glomerulonephritis
Answer: Pyelonephritis
Explanation
Pyelonephritis occurs most commonly in post-partum cows when bacteria enter via the urethra due to a postpartum uterine infection and vaginal damage at calving. The most common organisms found are coliforms or Corynebacterium renale. The resultant ascending infection causes renal swelling and pain (grinding teeth, swishing tail, repeatedly up and down), fever, and loss of appetite.
Urolithiasis is rare in dairy cows and urolithiasis in female ruminants is rarely symptomatic, as the stones usually pass readily. Glomerulonephritis would not be so painful and would not result in blood and pus in the urine.
Metritis could result in seeing pus and blood in a free catch urine sample, but the cow is unlikely to be colicky with metritis, and 2 weeks post-partum is a long delay in acute metritis (usually occurs a few days post-partum).
Claviceps purpura is the causative agent for which of the following?
- Aflatoxicosis
- Moldy corn poisoning
- Moldy sweet clover poisoning
- Ergotism
Answer: Ergotism
Explanation
The correct answer is ergotism. Claviceps purpura is a parasitic fungus found on rye, oats, wheat, and Kentucky bluegrass. Its toxicity comes from alkaloids and causes vascular constriction, thrombosis, gangrene, and vomiting, colic, diarrhea, and constipation.
Diagnosis is made by identifying ergot on the grain.
Comprehensive Summary of Ergotism in Animals
Important Concepts:
• Ergotism: Caused by ingestion of sclerotia from Claviceps purpurea affecting grains and grasses.
Infectious Agents:
• Claviceps purpurea: Produces ergot alkaloids like ergotamine and ergonovine.
Clinical Changes:
• Signs: Lameness, necrosis of tail/ears/hooves, poor reproduction, agalactia. • Species Affected: Cattle, pigs, sheep, and poultry.
Pathological Changes:
• Vasoconstriction: Leads to reduced blood flow, thrombosis, and necrosis. • Gangrene: Affects extremities in cold environments.
Diagnosis:
• Feed Analysis: Detecting ergot alkaloids via liquid chromatography-mass spectrometry.
Treatment:
• Cessation of Exposure: Remove contaminated feed. • Supportive Care: Provide shade, cooling, warmth, good bedding, and antimicrobial treatment if necessary.
For more details, visit the Merck Veterinary Manual on Ergotism.
You are presented with a Holstein heifer that is normal in size for her age but has severe skin lesions, resembling sunburn, over much of the body. Only the white areas seem to be affected (see image). You also find that several other heifers from the same pasture have milder skin lesions with the same distribution. You examine the pastures and feed and find that this Washington State pasture is full of Hypericum. What is the correct diagnosis?
- Primary perloline photosensitization
- Hereditary porphyria
- Phylloerythin photosensitization
- Primary Hypericin photosensitization
- Liver failure with hepatogenous photosensitization
Answer: Primary Hypericin photosensitization
Explanation
The plant Hypericum perforatum contains the chemical hypericin which, when ingested, localizes in skin and acts as a primary photosensitizing agent. Ingestion of other plants such as buckwheat, ryegrass, and whiteheads can also have this effect.
Secondary, or hepatogenous photosensitization, occurs when the liver fails to excrete phylloerythrin, the compound derived from the breakdown of a chlorophyll. Phylloerythin accumulates in the skin, resulting in photosensitization.
You are called out to see a 2-month old beef calf that collapsed this morning (see image). The farmer reports that the calf appeared well-nourished and was doing well a couple of days ago. You examine the calf and find temperature 100.6 F or 38.1 C, pulse 120 bpm, and respiratory rate 32 bpm with a slight expiratory grunt. The calf’s eyes are sunken and you estimate that it is 7-10% dehydrated based on decreased skin turgor. The ocular and oral mucous membranes appear congested. The abdomen is distended and palpation elicits a painful grunt. A quick field ultrasound shows several liters of peritoneal fluid and abdominocentesis yields blood tinged fluid. You quickly prepare the calf for a midline exploratory laparotomy and you identify a single, focal 1.5 cm perforating abomasal ulcer. With appropriate surgical and medical intervention, what is the calf’s prognosis?
- Grave (<10% chance of survival and recovery)
- Good (80-90% chance of survival and recovery)
- Excellent (>95% chance of survival and recovery)
- Guarded (20-40% chance of survival and recovery)
- Fair (50-70% chance of survival and recovery)
Answer: Grave (<10% chance of survival and recovery)
Explanation
This calf has an abomasal perforation and acute septic peritonitis based on the description. The prognosis is grave, even with prompt veterinary attention. The calf’s signs of dehydration, weakness, and expiratory grunt are additional poor prognostic indicators. Very few animals recover from diffuse peritonitis and those that do will have massive abdominal adhesions. Acute abomasal perforation through a single 1-2 cm ulcer occurs sporadically in young (2-4 month old) beef calves and the cause is unknown.
Abomasal ulcers in cattle are lesions where necrosis of the abomasal wall extends into the submucosal layer, surpassing the lamina muscularis mucosae. In contrast, more superficial lesions are termed erosions. These ulcers can manifest in various forms, each with distinct clinical implications.
Classification of Abomasal Ulcers:
1. Type I: Erosions or ulcers without hemorrhage. 2. Type II: Hemorrhagic ulcers. 3. Type III: Perforated ulcers with acute localized peritonitis. 4. Type IV: Perforated ulcers with acute diffuse peritonitis. 5. Type V: Perforated ulcers with peritonitis within the omental bursa.
This classification is primarily utilized during necropsy, as assessing the exact type through physical examination can be challenging.
Etiology and Pathogenesis:
The precise causes of abomasal ulceration remain not well understood. However, several factors have been associated with their development:
• Neoplastic Conditions: Lymphosarcoma of the abomasum. • Viral Infections: Erosions of the abomasal mucosa can develop in viral diseases such as bovine viral diarrhea, bovine leukemia virus, and malignant catarrhal fever. • Physiological Stress: High-producing, mature dairy cows are particularly susceptible within the first six weeks postpartum. Prolonged inappetence may lead to sustained periods of low abomasal pH, contributing to ulcer formation. • Mechanical Factors: Conditions like abomasal displacement or volvulus can increase luminal pressure, causing ischemia of the abomasal mucosa. • Stressors: Events such as transportation, introduction to new groups, heat exposure, and dehorning in calves may contribute to ulcer development.
In milk-fed calves aged 4–12 weeks, subclinical and nonhemorrhagic abomasal ulcers are common. Occasionally, calves younger than two weeks may develop acute, hemorrhagic ulcers that can perforate, leading to rapid mortality.
Clinical Findings:
The clinical presentation of abomasal ulcers varies based on the presence and severity of hemorrhage or perforation:
• Bleeding Ulcers: Cattle may be asymptomatic except for intermittent occult blood in the feces or may die acutely from massive hemorrhage. Common signs include mild abdominal pain, bruxism, sudden onset of anorexia, tachycardia (90–100 bpm), and fecal occult blood or melena that may be intermittent. • Perforated Ulcers: Signs include acute rumen stasis, generalized abdominal pain with reluctance to move, audible grunting or groaning with each breath, weakness, and dehydration. As the condition progresses, body temperature drops, and the animal becomes recumbent and dies within 6–8 hours.
In calves, perforating ulcers are more common than bleeding ulcers. Affected calves may exhibit a distended, gas- and fluid-filled abomasum palpable behind the right costal arch. Deep palpation may reveal abdominal pain associated with local peritonitis due to a perforated ulcer.
Diagnosis:
Diagnosing abomasal ulcers involves a combination of clinical evaluation and diagnostic tools:
• Clinical Examination: Observation of signs such as anorexia, bruxism, abdominal pain, and melena. • Fecal Occult Blood Test: To detect hidden blood in the feces. • Ultrasonography: Useful for detecting peritonitis associated with perforated ulcers. • Laboratory Tests: Hematology may reveal neutrophilia with a marked left shift and hemoconcentration in cases with diffuse peritonitis. In bleeding ulcers, the packed cell volume (PCV) can help determine the extent of hemorrhage, although PCV decreases only 4 hours after an acute hemorrhage. • Abdominocentesis: To assess peritoneal fluid for signs of peritonitis, such as increased total protein or d-dimer concentration and nucleated cell count.
Treatment:
Management strategies depend on the severity and type of ulcer:
• Dietary Management: Encouraging the animal to eat is crucial, as food acts as a buffer, increasing abomasal pH. • Antimicrobial Therapy: Broad-spectrum antibiotics are indicated for perforating ulcers to prevent or treat peritonitis. • Acid Suppression: H2-receptor antagonists like cimetidine and ranitidine, as well as proton pump inhibitors such as omeprazole, can effectively increase abomasal pH. However, the required dosages can be high, making treatment expensive. • Blood Transfusion: In cases of significant hemorrhage, transfusions may be necessary. A single transfusion of 4–6 liters of blood is often sufficient, but some cattle may require multiple transfusions over several days.
The prognosis varies:
• Localized Peritonitis: Generally favorable with appropriate medical therapy and dietary management. • Diffuse Peritonitis: Grave prognosis; affected animals rarely respond to treatment.
Prevention:
Preventive measures focus on minimizing stress and maintaining consistent feed intake:
• Stress Reduction: Avoid unnecessary stressors such as transportation, regrouping, and overcrowding. • Diet Management: Ensure animals have continuous access to feed to prevent prolonged periods of inappetence and low abomasal pH.
A new feedlot owner purchased several new cattle two days ago. All appeared well at the time of purchase. He kept them isolated, starting them on the same feeding program as the rest of his herd. Yesterday he noticed that several of the animals had diarrhea and appeared painful in the abdomen. This morning, one has died and others appear to be even more ill. You examine an ill cow and find that the temperature is 100.8°F, heart rate is 110 bpm, and respiratory rate is 60 bpm. You note the absence of ruminal sounds and mild neurologic deficits, including a slow pupillary light reflex and sluggish palpebral reflex. Similar findings are observed in other animals. You obtain a ruminal sample and find that the pH is 4.8. How can this facility prevent this problem in the future?
- Maintain the cattle on pasture or hay diet
- Deworm all of the new cattle to address intestinal parasites
- Increase the amount of grain fed to cattle gradually
- Utilize finely-ground grain instead of whole grain
Answer: Increase the amount of grain fed to cattle gradually
Explanation
The cattle are showing signs of rumen acidosis. Changing cattle to a grain diet quickly/abruptly is not recommended as this can cause rumen acidosis from grain overload.
The best way to prevent this condition in cattle that are being changed to a grain diet is to gradually increase the amount of grain fed to the cattle and make sure they have plenty of roughage during the transition.
Deworming may have benefits, but will not impact this particular condition.
Maintaining the cattle on pasture is not realistic in a feedlot.
Whole grain is less likely to induce this condition than finely-ground grain.
The 35-day postpartum recumbent dairy cow in this image has normal vital parameters, appetite, and milk production but has mucus and pus draining from her vulva. Speculum exam shows this material exiting the cervix. Rectal exam shows that she has an involuting uterus and normal ovaries. Which of the following treatments should be administered to help treat this condition and have the fewest negative economic effects such as prolonged milk withdrawal?
- Intrauterine chloramphenicol
- Systemic diethylstilbestrol
- Intrauterine penicillin
- Systemic ceftiofur
- Intrauterine metronidazole
Answer: Systemic Ceftiofur
Explanation
The diagnosis is endometritis. This is based on the involuting post partum uterus and the normal vital signs (TPR).
Intrauterine penicillin (after 30 days) or tetracycline or ceftiofur can be beneficial. The negative impact can be antibiotic residues in milk (up to 80 hours for penicillin and 96 hours for tetracycline in milk) and in tissues (up to 12 days for penicillin), so some prefer to use dilute povidone iodine, or uterine lavage with saline.
Systemic ceftiofur achieves adequate intrauterine levels and is thus the safest and best of the options listed.
Prostaglandins can also be given to “short cycle” the cow which will aid in treating the endometritis.
The other drugs listed are not legal for use in the USA, and could cause harmful residues to appear in milk.
While you are visiting a hobby farm to address other concerns, the farm owner mentions that he has a question about his small cattle herd. A few years ago, two of his cows died after being moved from a sparse, overgrazed pasture to a lush, green pasture. His veterinarian advised him that the cattle had signs of acute bovine pulmonary emphysema and edema (ABPEE), which was confirmed on necropsy. The farm owner recently purchased additional land and is planning to relocate his cattle to a new pasture later this week, but is concerned because the new pasture is very lush and green. Is there any medication that he can give to prevent ABPEE in his herd?
- Treat all cattle with monensin one day before turning out on pasture
- Treat all cattle with monensin on first day of clinical signs
- Treat all cattle with lasalocid one day before turning out on pasture
- Treat all cattle with lasalocid on the first day of clinical signs
Answer: Treat all cattle with monensin one day before turning out on pasture
Explanation
There are a number of strategies to prevent ABPEE in cattle herds. Increasing hay prior to moving the cattle and limiting access to the new pasture are both management methods that would decrease risk.
Monensin and lasalocid are medications that are effective at preventing ABPEE, by inhibiting the bacteria that convert L-tryptophan to 3-methylindole.
Both medications are ineffective once clinical signs set in. Lasalocid needs a 6 day pretreatment window to be effective, while monensin is effective when given one day before turning out to pasture. Therefore, if the farmer wants to move his cattle in 2-3 days, monensin is the best available treatment option.
What is the approximate gestation length of a cow?
- 250 days
- 320 days
- 300 days
- 280 days
Answer: 280 days
Explanation
The correct answer is 280 days.
The normal respiratory rate of an adult cow resting in the shade at 60F is
- 8 to 12 breaths per minute
- 36 to 48 breaths per minute
- 12 to 36 breaths per minute
- 48 to 60 breaths per minute
Answer: 12-36 breaths per minute
Explanation
This cow, because it is resting in the shade on a cool day, would be likely to have a rate toward the lower end of the range, whereas a cow in the sun on a hot day or an excited cow might approach the upper limit. Calves have a higher normal resting rate in the area of 30 to 60 breaths per minute.
Cows ovulate after which of the following?
- Ovulation is induced when male mounts a cow
- 24-30 hours after onset of estrus
- 12-16 hours before onset of estrus
- 36-48 hours after the onset of estrus
Answer: 24-30 hours after onset of estrus
Explanation
The correct answer is 24-30 hours after the onset of estrus. Cows actually ovulate after they are out of estrus because estrus usually lasts 8-18 hours.
You are called out to visit a feedlot experiencing an outbreak of disease among its beef cattle during the early spring. Several animals are anorectic and appear disoriented, getting stuck in corners, circling, and leaning against objects. One heifer has a drooping ear, deviated muzzle and flaccid lip on the right side as well as a decreased menace response. The same animal is salivating continuously. You perform cerebrospinal fluid analysis on that animal and note an elevated protein concentration of 100mg/dl (normal 11-30mg/dl) and a mild increase in CSF cell count of 50/ul (normal O-10/ul), all monocytes. You perform a necropsy on a recently deceased affected animal and note congestion of the meninges. CNS histopathology shows microabscesses of the pons, medulla oblongata, and anterior spinal cord. Which of the following is the best treatment option for the animals on the feedlot?
- Ivermectin
- Penicillin
- Cull all exposed animals
- Thiamine supplementation
Answer: Penicillin
Explanation
The clinical description is highly suggestive of Listeriosis.
The SF findings (elevated protein and monocytosis) and description and location of CNS microabscesses make Listeria the clear top differential.
High doses of penicillin are generally considered effective against Listeriosis although more severely affected animals have a poorer prognosis.
It is not considered necessary to cull all exposed animals.
Progesterone levels are highest in cattle during what period?
- Estrus
- Diestrus
- Proestrus
- Metestrus
Answer: Diestrus
Explanation
The correct answer is diestrus. Progesterone levels begin to drop during prostrus and are at their lowest in estrus.
During metestrus, progesterone levels begin to rise again.
A group of Angus heifers were turned into an old corral area 8 hours earlier in the day. Now one heifer has convulsed and died and several have dyspnea, polypnea, and weakness. You arrive and, after a quick physical exam on one, take a blood sample, which is chocolate-brown in color. The plants shown in the photo contain what toxic principle?
- Nitrate
- Oxalates
- Cyanide
- Tryptophan
- S-methylcysteine sulfoxide
Answer: Nitrate
Explanation
The plant shown in the picture is Amaranthus.
Amaranthus is commonly called pigweed and accumulates nitrates. Nitrates are converted in the rumen to nitrites, which convert hemoglobin to methemoglobin (Fe+3), which cannot bind or transport oxygen.
Even if you cannot identify the plant in the photo, the chocolate-brown color of the blood should lead you to the correct answer of nitrate poisoning.
You are presented with a 5 week old female Jersey calf with fever, tachypnea, tachycardia, lethargy, poor appetite and dyspnea. On auscultation, the ventral thorax is bilaterally harsh on both inspiration and expiration, with wheezes, crackles and popping sounds. The lateral view radiograph of the thorax is shown. What can be determined from the radiograph?
- There is severe ventral consolidation of the lung
- There is a large volume of fluid in the thoracic cavity
- The cardiac shadow is enlarged
- There is a pneumothorax and the lungs have collapsed
- The middle sized and large airways are open and normal
Answer: There is severe ventral consolidation of the lung
Explanation
This is a radiograph of severe pneumonia in a calf with air bronchograms in the ventral lung fields. Air bronchograms indicate consolidation of the ventral lung. On exam of this calf, you would expect the lung to percuss dull ventrally, and be meaty and consolidated on post mortem.
Enzootic Pneumonia of Calves
Definition:
• Common respiratory disease in young dairy, veal, or beef calves caused by viral and bacterial pathogens.
Etiology:
• Pasteurella multocida, Mannheimia haemolytica, Histophilus somni, Mycoplasma bovis. • Environmental stressors: poor ventilation, high humidity, crowding, poor immunity.
Clinical Signs:
• Depression, lethargy, anorexia. • Respiratory distress, fever, nasal discharge. • Coughing, increased respiratory rate.
Diagnosis:
• Clinical signs, thoracic ultrasonography. • Culture and sensitivity testing.
Treatment:
• Broad-spectrum antimicrobials: oxytetracycline, florfenicol, ceftiofur. • NSAIDs: flunixin meglumine, meloxicam.
Control:
• Colostrum intake, vaccination protocols, proper ventilation. • Avoid crowding, “all-in/all-out” management.
You are called over to a beef ranch to evaluate a herd with a history of diarrhea, reproductive problems, and occasional cerebellar hypoplasia. You suspect an underlying infection with bovine viral diarrhea. How is this virus most likely being maintained in the herd?
- Wildebeest carriers of the virus which are asymptomatic
- The insect reservoir Culicoides sonorensis
- Persistently-infected carrier cattle that were infected as fetuses
- Sheep carriers of the virus which are asymptomatic
- Cattle that were persistently infected with both the noncytopathic and cytopathic biotypes of BVD virus shortly after birth
Answer: Persistently-infected carrier cattle that were infected as fetuses
Explanation
A susceptible non-immune cow carrying a fetus between 60 and 150 days gestation, if infected by a non-cytopathic biotype of BVD, can pass the virus to her fetus which may become persistently infected. This calf can spread virus to herd mates for the duration of its life.
***PowerLecture: Bovine Viral Diarrhea
Comprehensive Information on Bovine Viral Diarrhea (BVD) for NAVLE Preparation
Definition & Etiology:
• Bovine Viral Diarrhea (BVD): A disease caused by Bovine viral diarrhea virus (BVDV), a Pestivirus in the Flaviviridae family. • Transmission: Mainly through direct contact with infected animals or contaminated fomites. Vertical transmission can lead to persistently infected (PI) calves.
Pathophysiology:
• BVDV can cause immunosuppression, leading to secondary infections. • Cerebellar Hypoplasia: In utero infection during mid-gestation can result in cerebellar hypoplasia in calves, characterized by ataxia, tremors, and inability to stand properly.
Clinical Signs:
• Diarrhea, fever, nasal discharge, immunosuppression, and mucosal disease in PI animals. • Neurological signs in calves with cerebellar hypoplasia include ataxia, intention tremors, and hypermetric gait.
Diagnosis:
• PCR and virus isolation are used to detect BVDV. • Serology to identify antibodies in the dam or calf.
Prevention:
• Vaccination: Prophylactic vaccination of breeding animals is essential to prevent vertical transmission and cerebellar hypoplasia in calves.
Treatment:
• No specific antiviral treatment; focus on supportive care and prevention of secondary infections.
For more details, refer to the Merck Veterinary Manual
Which of the following does not play a role in transmitting and causing infectious bovine keratoconjunctivitis?
- Sunlight
- Ticks
- Flies
- Moraxella bovis
Answer: Ticks
Explanation
The correct answer is ticks. Flies are involved in transmission. Most outbreaks occur during the summer when UV light is at its strongest, and Moraxella bovis is the causative agent to IBK or pink-eye.
***PowerPage: Infectious Bovine Keratoconjunctivitis (Pinkeye)
Infectious Keratoconjunctivitis (Pinkeye) in Animals
Definition:
• Infectious Keratoconjunctivitis: Inflammatory condition of the conjunctiva and cornea caused by various infectious agents.
Causative Agents:
• Cattle: • Bacteria: Moraxella bovis, M. bovoculi, M. ovis, Mycoplasma spp (M. bovis, M. bovoculi), Chlamydia pecorum. • Viruses: Bovine herpesvirus type 1, IBR virus. • Other: Listeria monocytogenes, Thelazia spp (eyeworms).
Symptoms and Clinical Changes:
• General Signs: Photophobia, blepharospasm, epiphora, conjunctivitis, keratitis, corneal opacity/ulceration, mucopurulent discharge, polyarthritis (in sheep and goats). • Severe Cases: Corneal rupture, permanent blindness.
Diagnosis:
• Clinical Signs: Photophobia, discharge, corneal changes. • Microbial Culture: From affected eyes. • PCR: Detects Chlamydia, Mycoplasma spp.
Treatments:
• Antibiotics: • Cattle: Long-acting oxytetracycline (20 mg/kg, IM/SC), tulathromycin (2.5 mg/kg, SC), ceftiofur (6.6 mg/kg, SC), florfenicol (20 mg/kg, IM). • Sheep/Goats: Topical oxytetracycline. • Supportive Care: NSAIDs, atropine (1% ophthalmic ointment), eye patches, third-eyelid flap, tarsorrhaphy. • Management: Improved hygiene, fly control, vaccination (controversial).
Prevention:
• Management Practices: Reduce dust, provide shade, separate infected animals, use insecticides. • Vaccination: Controversial but may help some herds.
Key Points:
• Early Identification: Reduces animal suffering and disease spread. • Risk Factors: Addressing these is crucial for control.
For detailed information, visit the Merck Veterinary Manual
Which of the following hormones would be most effective and economical in raising the amount of milk produced by a dairy cow?
- Parathyroid hormone (PTH)
- Calcitonin
- Insulin
- Somatotropin
- Thyroid stimulating hormone (TSH)
Answer: Somatotropin
Explanation
Also called growth hormone, injections of bovine somatotropin (BST) every 14 days can significantly prolong the lactation curve and result in increased milk production.
Louse infestations in cattle sometimes require veterinary intervention. Which of the following statements is false?
- Mallophaga are biting lice
- Lice are usually species-specific
- Anoplura are sucking lice
- Adult lice have 8 legs
Answer: Adult lice have 8 legs
Explanation
The false statement is adult lice have eight legs. Adult lice have 6 beautiful little legs.
The other statements are true. Remember that Anoplura lice can cause anemia if their numbers are sufficient.
Lice infestations, or pediculosis, are a significant concern in cattle, particularly during the winter months when animals are housed closely together. These infestations can lead to discomfort, decreased productivity, and, in severe cases, anemia. Understanding the pathogenesis and transmission of lice in cattle is essential for effective management and control.
Pathogenesis:
Lice are obligate ectoparasites that complete their entire life cycle on the host. They are typically transmitted through direct contact between animals. However, Haematopinus quadripertusus, the cattle tail louse, can also be transmitted by the horn fly (Haematobia irritans).
Infestations tend to be heaviest in the winter, decreasing greatly as summer approaches. Cattle, especially young animals, may be infested with multiple species of lice simultaneously. Solenopotes capillatus and Haematopinus eurysternus infestations are more often recognized on mature animals, whereas Linognathus vituli is more common on calves and on dairy cattle. 
Disease Transmission:
While lice are primarily transmitted via direct contact between animals, Haematopinus quadripertusus can also be transmitted by the horn fly (Haematobia irritans). 
Lice infestations can lead to secondary dermal infections, and lice can transmit diseases and be intermediate hosts for other parasites.
Predilection Sites of Cattle Lice:
Different louse species prefer specific areas on the host:
• Chewing Lice: • Bovicola (Damalinia) bovis (cattle biting louse, red louse): Most commonly found on the dorsum; infestations may extend cranially to the head and caudally to the tailhead. • Bloodsucking Lice: • Linognathus vituli (long-nosed cattle louse): Most commonly found over the withers, lateral shoulders, and dewlap; may have a generalized distribution over the animal. • Solenopotes capillatus (little blue cattle louse): Found in distinct clusters, mainly on the head and face; heavy infestations may extend to the dewlap or surround the eyes. • Haematopinus eurysternus (short-nosed cattle louse): Often found on the front half of the host, from ears to dewlap; infestations tend to be heavier in cranial portions of the body, including ears, during warm weather. • Haematopinus quadripertusus (cattle tail louse): Adults often confined to the tail; eggs commonly noted on the tail switch.
Recognizing these predilection sites aids in the diagnosis and targeted treatment of lice infestations in cattle.
Effective management of lice in cattle involves regular monitoring, maintaining good husbandry practices, and implementing appropriate treatment strategies when infestations are detected.
A cattle herd has recently been introduced to a lush, green alfalfa pasture. In the days since this transition, the producer has found several cattle dead in the pasture. He calls you out to his farm to address this issue. When you arrive, he has identified three cows that are reluctant to move and do not appear to be grazing. On exam, you observe that these cattle have abdominal distention, most prominently on the left side. You also notice an increased respiratory rate, with one of the cows holding its neck extended as if struggling to breathe. In addition to providing emergency treatment for the affected cattle, what management change do you recommend?
- Feeding finely ground grain rations
- Twice daily drenching with anti-foaming agents
- Administration of anti-foaming agents via stomach tube
- Feeding hay as 1/4 of the diet
Answer: Twice daily drenching with anti-foaming agents
Explanation
The history and clinical signs in this case suggest a diagnosis of pasture bloat (primary ruminal tympany, aka frothy bloat). This condition is most common in cattle that have recently been turned out onto lush legume pasture. The best way to effectively prevent frothy bloat is twice daily drenching with anti-foaming agents.
Once daily drenching is not adequate. It is also less practical to pass a stomach tube on each cow to administer the anti-foaming agents.
Feeding finely ground grain rations can contribute to bloat in feedlot cattle.
If using grass hay to prevent frothy bloat, the hay must constitute at least 1/3 of the diet.
Bloat, or ruminal tympany, is a condition characterized by excessive accumulation of gas in the rumen, leading to distension and potential respiratory or circulatory compromise. It is predominantly observed in cattle and can be classified into two primary types:
1. Frothy Bloat (Primary Ruminal Tympany): This form involves the entrapment of fermentation gases within a stable foam, preventing their release through eructation. 2. Free-Gas Bloat (Secondary Ruminal Tympany): In this type, gas accumulates freely above the ruminal contents due to physical obstructions or motility disorders that impede eructation.
Etiology and Pathogenesis of Frothy Bloat:
Frothy bloat occurs when normal fermentation gases are trapped in a stable foam within the rumen, inhibiting their coalescence and subsequent expulsion. Several factors contribute to foam formation:
• Dietary Factors: Grazing on legume-rich pastures, such as alfalfa, ladino, and red and white clovers, is a common cause. These forages are high in soluble proteins and rapidly digestible carbohydrates, which can lead to foam formation. Other contributing forages include young green cereal crops, rape, kale, turnips, and legume vegetable crops. In feedlot settings, high-grain diets with finely ground feed particles can also predispose cattle to frothy bloat. • Foaming Agents: Soluble leaf proteins, saponins, and hemicelluloses are believed to be primary foaming agents. They form a monomolecular layer around gas bubbles, stabilizing the foam, especially at a ruminal pH of around 6. • Saliva Production: Salivary mucin has antifoaming properties; however, the production of saliva is reduced when animals consume succulent forages, decreasing its protective effect. 
Clinical Findings:
The clinical presentation of frothy bloat includes:
• Abdominal Distension: Notably on the left side, due to ruminal enlargement. • Discomfort: Manifested as restlessness, kicking at the abdomen, or frequent lying down and rising. • Respiratory Distress: Difficulty breathing, open-mouth breathing, and extension of the head and neck, resulting from pressure on the diaphragm. • Sudden Death: In severe cases, compression of thoracic structures can lead to circulatory failure and death.
Diagnosis:
- Diagnosis is based on clinical signs and the inability to relieve the distension by passing a stomach tube, as the foam prevents gas release. Confirmation can be achieved by administering an antifoaming agent via the tube; rapid improvement supports the diagnosis of frothy bloat.
Treatment:
Immediate intervention is crucial:
• Antifoaming Agents: Administration of agents such as poloxalene (25–50 g) as a drench or via a stomach tube can reduce foam stability, allowing gas release. Other agents include polymerized methyl silicone (30–60 mL) or vegetable oils like peanut, sunflower, or soybean oil (60 mL). • Emergency Measures: In life-threatening situations where other methods are ineffective, rumenotomy may be performed to release the gas directly.
Control and Prevention:
Preventive strategies focus on dietary management:
• Pasture Management: Avoid grazing on high-risk pastures during peak bloat seasons. Introducing cattle to legume pastures gradually and ensuring they are not overly hungry can reduce risk.
• Feed Additives: Incorporating antifoaming agents like poloxalene into feed or providing it in molasses blocks can help prevent frothy bloat. Ionophores, such as monensin, have also been shown to decrease the incidence of frothy bloat in feedlot cattle. 
• Dietary Composition: Ensuring a balanced diet with adequate roughage can promote normal ruminal function and reduce the likelihood of bloat.
Regular monitoring and prompt management of at-risk cattle are essential to prevent the severe consequences of frothy bloat.
A three-year old Jersey cow presents for decreased milk production and weight loss. On physical exam, a hard, non-painful swelling of the mandible is identified. Radiographs of this region show lysis and productive bone lesions, with distortion of the teeth in the area. What is the most likely cause for these findings?
- Vesicular stomatitis
- Actinomycosis
- Actinobacillus lignieresii
- Osteosarcoma
Answer: Actinomycosis
Explanation
This cow has become infected with Actinomyces bovis (lumpy jaw) as a result of sustaining an injury in the mucous membranes, often from eating hard scabrous feeds. Actinomyces bovis is part of the normal oral and rumen flora and can become a source of infection when cows consume items that traumatize their mouths.
The lesion classically causes a hard non-painful swelling of the mandible or maxilla along with productive and destructive bony changes. Teeth may be lost.
Osteosarcoma is very uncommon in cattle and is therefore a poor answer choice.
Vesicular stomatitis will not cause a hard non-painful swelling. Instead, you may see oral ulceration as a result of ruptured vesicles along the tongue. This virus can also cause lesions of the feet and teats. Cows infected with vesicular stomatitis will most likely be salivating, not eating, depressed, and febrile.
Actinobacillus lignieresii is the causative agent of woody tongue. In this case, you would expect to see a large firm tongue on physical exam. Sodium iodide has been used to treat lumpy jaw, but this will only arrest the lesion.
***PowerLecture: Oral Cavity Diseases
You are hired by the potential buyer to examine a valuable 3-month old calf for purchase as part of a pre-purchase examination. You note that the calf appears healthy other than having a temperature of 103F, 39.4 C and having some small raised lesions in the mouth around the gums of the incisors and on the dental pad, as shown in the photo. You suggest some lab tests and another exam in three weeks, and tell the buyer that you think the calf most likely has
- Pseudocowpox
- Foot-and-Mouth disease
- Bovine papular stomatitis (BPS)
- Bovine viral diarrhea (BVD)
- Contagious ecthyma
Answer: Bovine popular stomatitis (BPS)
Explanation
BPS is one of two parapox viruses that affect cattle; the other is pseudocowpox. The third parapoxvirus is contagious ecthyma of sheep and goats. Humans can get all three.
BPS is a common and usually mild “calfhood” disease, often unnoticed, but it has caused significant mortality in some groups of calves (perhaps due to some immunosuppression).
The best course of action is to isolate this calf and rule out BVD by testing for it, then wait to see if the calf recovers in about three weeks. The raised lesions, and lack of other oral lesions, and lack of Gl signs tend to make BPS more likely here than BVD.
You are called by a beef rancher located in the northern California oak foothills one day in March after an unusual spring snowstorm that dumped a foot of wet snow two days earlier. You are asked to diagnose and treat several calves in the 3- to 5- month old age range which are listless and weak. You do a physical exam and find elevated heart and respiratory rates, but normal rectal temperatures. The most remarkable finding is marked edema of the perineum and vulva of the calves (see image). What is the best diagnosis based on these signs and history?
- Clostridium hemolyticum infection (redwater)
- Lead toxicity
- Acute oak toxicosis
- Bovine virus diarrhea
- Malignant catarrhal fever
Answer: Acute oak toxicosis
Explanation
The reason that oak toxicosis may occur in this scenario is as follows: the snow knocks down the budding oak limbs which are eaten by curious calves who cannot reach the grass.
The calves develop both renal and Gl signs as the tannins damage the mucosa. Many develop hemorrhagic diarrhea and renal tubular necrosis. Some tannins are hydrolyzed in the rumen to gallic acid and pyrogallol, which are both very toxic to the renal tubules.
Treatment is aimed at flushing out the toxins (intravenous fluids) and protecting the gastrointestinal tract.
Prevention is best; and the animals will avoid eating the oak if they are offered hay immediately during the storm.
A California dairy herd has been experiencing repeat breeders, several abortions, weak calves and some congenital defects including cerebellar hypoplasia, cataracts, and thymic hypoplasia. Which of the following disease agents should you investigate as the most likely cause of these problems?
- Mycobacterium avium subsp paratuberculosis
- Malignant catarrhal fever virus
- Vesicular stomatitis virus
- Mycoplasma bovis
- Bovine viral diarrhea virus (BVDV)
Answer: Bovine Viral Diarrhea Virus
Explanation
BVD virus causes all these problems, as well as persistently infected neonatal calves when the fetus is infected with the NCP biotype of BVD at 2 to 5 months gestational age.
***PowerLecture: Bovine Viral Diarrhea
What is the proper anatomical location for performing a lumbosacral CS tap in cattle?
- Between the dorsal spinous process of L4 cranially and L5 caudally and the tuber sacrales laterally
- Between the dorsal spinous process of S1 cranially and S2 caudally and the tuber sacrales laterally
- Between the dorsal spinous process of L7 cranially and S1 caudally and the tuber sacrales laterally
- Between the dorsal spinous process of L6 cranially and S1 caudally and the tuber sacrales laterally
Answer: Between the dorsal spinous process of L6 cranially and S1 caudally and the tuber sacrales laterally
Explanation
The correct answer is between the dorsal spinous process of L6 cranially and S1 caudally and the tuber sacrales laterally.
