| Scott Fritz, DVM, ABVT Toxicologist Beef Cattle Institute Kansas State University Scottfritz@vet.k-state.edu |
Sources
Feed, Protein Tubs, Fertilizer-contaminated water
Mechanism
Rumen urease cleaves urea making ammonium, that reaction causes the rumen pH to climb. At pH >8, the reaction selects for ammonia that is absorbed and transported to the liver. The liver’s ability to metabolize ammonia is overwhelmed leading to hyperammonemia.
Signs
Rapid onset (20-60 minutes) of uneasiness, bloat, dyspnea, recumbency, paddling, cyanosis, and death. The rapid progression from consumption to death precludes the formation of any reliable lesions. Rumen pH will typically remain elevated for ~24, pH paper is a cheap and effective way for in-field evaluation.
Treatment
Treatment is based on lowering the pH and diluting the urea concentration. The most effective way to accomplish this is a rumen infusion of acetic acid (vinegar) and cold water. Animals should be triaged with treatment directed towards clinical animals that are not yet recumbent. Survivors generally have no lasting effects.
Diagnosis
Post-mortem diagnosis is based on ammonia concentrations in ocular fluid as well as rumen pH. Rumen content should be frozen ASAP because the ammonia will volatize off the sample.
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