Bovine CSI: Cases of Toxic or Infectious Disorders from Herd Investigations
ACVIM 2008
Christine B. Navarre, DVM, MS, DACVIM
Baton Rouge, LA, USA

Introduction

Herd investigations of disease and death in beef and dairy herds can be challenging. A good investigation starts with a thorough understanding of what the problem actually is, and a good history of the events in question. Miscommunication is the cause of many disease investigation failures. It's important to talk to the person who actually takes care of the animals on a daily basis. A good investigation also starts at the farm. Even with a very good description of a problem over the phone, there is no substitute for seeing things first hand. A thorough physical examination of sick animals should be a top priority in a disease investigation. Cattle are prey species and try to hide the fact that they are sick, so examining normal animals can also be helpful. A necropsy absolutely offers the best chance of getting a diagnosis for an ongoing problem. It can also reveal other herd health problems not related to the current problem. Many sudden death outbreaks are actually precipitated by underlying management issues which need to be addressed.

Case 1

The time of year is June. The problem is at a prison ranch with several hundred head of commercial cross-bred beef cattle. Several cows and calves in one group of about 75 head were found dead. A calf was presented to the veterinary school with neurologic signs. It had seizures and died shortly after presentation. A necropsy was unremarkable. In total 7 cows and 4 calves died over two days. No other groups on the ranch had any health issues. The cattle were on Bermuda grass pasture and drinking from a pond. There were no recent changes in location or feeding. Cattle were in excellent body condition.

What other questions might be important in this case? What would be the differential list for sudden death and neurologic signs in both adult cows and calves?

Case 2

This case occurred in a coastal parish of Louisiana in January 2006. This parish was devastated by Hurricane Rita in September of 2005. This ranch had approximately 800 commercial cows, 80 Quarter Horse mares and 15,000 alligators. The animals were evacuated prior to the hurricane then returned several weeks later after the storm surge had receded and fence repairs were done. The complaint was late term abortions in both the cattle and mares.

What other questions might be important in this case? What would the differentials be for these abortions? What tests might be helpful in determining a cause?

Case 3

This case occurred in February of 2006. A herd of about 200 commercial beef cows was having abortions in some cows and a low calving percentage compared to previous years. Bulls are turned out all year in this herd, but most cows have calved in January/February in previous years. This herd vaccinates for reproductive diseases yearly. They bought "hurricane cattle" in the fall and commingled them with the original herd.

What other questions might be important in this case? What would the differentials be for this problem? What tests might be helpful in determining a cause?

Case 4

This case occurred in the fall of 2005 in area not affected by the 2005 hurricanes. The problem occurred in a group of Brangus weanlings commingled from 3 sale barns. The main clinical signs were coughing and lameness that appeared unresponsive to multiple antibiotics treatments.

What would the differentials be for this problem? What tests might be helpful in determining a cause? What recommendations should be made to this producer?

Case 5

This problem occurred in late winter and early spring of 2007 in a group of about 50 commercial cows. The cattle are turned into marsh land to graze in the winter, then moved to pasture protected by levees in the spring. While still on marsh pasture, several cows were found dead. The cattle were moved immediately out of the marsh to spring pastures. One bull and a few cows were noted to be walking along normally before suddenly falling down. They would stay down about 5 minutes, get up and walk off like nothing had happened. They did this repeatedly. One cow made compulsive back and forth motions with her head. The affected cows were in poor body condition whereas the normal cows were in good condition. One cow was presented to the veterinary school. She had a swollen brisket that was determined to be from trauma on necropsy. No other gross or histologic abnormalities were found.

What other questions might be important in this case? What would the differentials be for this problem? What tests might be helpful in determining a cause?

Case 6

This case occurred in early June of 2007. Several adult cows out of a herd of 80 were found dead. Some died, some were euthanized. A necropsy on two revealed no lesions on gross or histopathologic examination. Several cows appear stiff, had hunched backs, and were picking up their feet alternately. Some were ataxic and dribbling urine. They did not seem to have a normal flight zone as they were much more approachable than was expected. Another necropsy revealed mild vacuolization in spinal cord.

What other questions might be important in this case? What would the differentials be for this problem? What tests might be helpful in determining a cause?

Case 7

This case occurred in November of 2007. Five Holstein calves varying age from 4-8 weeks were found dead one morning. There was a history of some anorexia problems and a few sporadic deaths. The temperature was in the 80s the previous day and dropped into the 30s over night. On necropsy the calves were thin, there was copious amounts of fluid in abdomen, chest, and pericardial sac. The liver was swollen and there was edema in omentum, lungs, other tissues. The heart was enlarged and flaccid. Two sick calves were examined and had fever, jugular distension/pulses and gallop rhythms on heart auscultation.

What other questions might be important in this case? What would the differentials be for this problem? What tests might be helpful in determining a cause?

References

1.  Beasley VR, et al. Vet Clin N Am: Food An Pract 1989; 345-362.

Speaker Information
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Christine Navarre, DVM, MS, DACVIM
Louisiana State University
Baton Rouge, LA


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