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Rebecca Childers, Laboratory Technician Jennifer McCarthy, Assistant Chemist
Robert Everson, Ph.D., Analytical Chemist
Laboratory Supervisor Stephen B.Hooser,DVM, Ph.D., Veterinary Toxicologist, Head, Toxicology Section

The sudden death of large numbers of previously healthy animals can often be attributed to poisoning. Within the past few months, numerous cattle and swine deaths in Indiana have been caused by a wide variety of toxic agents.  This winter, a large number of hogs died when they were fed from a bucket in which an insecticide had been transported.  Insecticides which are used for field application are so potent and concentrated that even the small amount remaining in the bucket was enough to kill a large number of animals.

Since January, three poisonings with 3 completely different toxins have resulted in the sudden death of large numbers of cattle.  In the first, the owner noticed several dead cows one morning.  As he inspected the dead animals, 2 more cows dropped dead near him.  Examination of the rumen contents of these cows showed that they had accidentally ingested clippings from Japanese yew bushes.  Japanese Yew is an evergreen shrub that is very commonly used for ornamental landscaping. Even small quantities of this plant are sufficient to kill an adult cow.

In the second case, again the owner arrived at the pasture one morning and found many dead cows.  At necropsy, no Japanese Yew plants were found in the rumen.  However, analysis of the rumen contents revealed the presence of an organophosphate

insecticide.  In this case, the insecticide was also found in the contents of the feed trough, where it had inadvertently been incorporated.

In the third case, the owner arrived at his pasture early one morning and discovered 3 dead cows. Over the next 24hrs, another 12 cows and calves died.  At necropsy, no Japanese Yew was found in the rumen.  Analysis of the rumen contents revealed no insecticides or other pesticides.  However, in this case, analysis of the hay showed that it contained high

concentrations of nitrates as did the ocular fluid of one of the dead cows. Removal of the hay prevented any further deaths.  Fortunately, in this case, the owner realized that the deaths began within a day after putting new hay bales in the pasture for the cattle. As soon as the deaths began, he removed those bales and the deaths soon ceased.  Other hay, which was baled earlier in the year, was unaffected.  We suspect that a combination of heavy fertilization, late summer drought, and the growth of nitrate -accumulating plants all contributed to the high nitrate concentrations found in these third cutting hay bales.

From these cases, it is clear that there can be numerous causes of sudden death in livestock.  Often, a rapid diagnosis is necessary to prevent further losses.  Therefore, when such cases occur, and in consultation with the owner, referring veterinarian or (pathologist), and lexicologist, a battery of tests will be started. These tests will begin analysis for all of the most common causes of sudden death in the affected species.  This will greatly speed up the time necessary to find the cause of the poisoning since we will not have to wait for a negative result of one test before proceeding onto the next. For cattle, this testing would include assays for insecticides, alkaloids, and nitrates.  For sheep, copper would also be included.  Since horses are not as sensitive to nitrates, deaths involving horses would not start with nitrate testing, but would include monensin.  While this approach will add to the initial cost of testing, beginning all of the tests immediately will allow the most rapid diagnosis of the cause of the problem.

The battery of tests which will be run for each species (and the tissues needed to run those tests) are:



organophosphates (Rumen contents, feed, brain, liver heparinized blood)
carbamatesnitrate (Rumen contents, feed)
alkaloids(Taxus) (Eyeball [frozen], feed, water) (Rumen contents, liver)



same as for cattle plus coppe (Liver, kidney, feed)



organophosphates (Stomach contents, feed brain, liver heparinized blood)
carbamates (Stomach contents, feed
alkaloids (Taxus) (Stomach contents)
monensin (Stomach contents, feed)

Pigs(cost of this screen)


organophosphates    (Stomach contents, feed, brain, liver, heparinized blood)
carbamates          (Stomach contents, feed)
Na+/Water Deprivation  (cerebrospinal fluid, brain,


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Phone: 765-494-7440
Fax: 765-494-9181

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Phone: (812) 678-3401
Fax: (812) 678-3412

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