Because many of these compounds are excreted in the urine, kidney and urine samples should also be submitted. Salt poisoning or water deprivation causes sodium imbalance which can be detected by analyzing brain tissue and serum. Suspected feed is the best submission for diagnosis of toxicosis due to nonprotein nitrogen feed additives . Abnormal levels of ammonia and urea may be detected in the stomach or rumen contents and heparinized whole blood or serum if these samples are collected immediately after death and are frozen immediately after collection and remain frozen during transportation to the laboratory. This is another exception to the general rule of never freezing whole blood samples.
Autolysis greatly decreases usefulness of analysis.
A set of tissues in formalin should also be sent to the laboratory. When warfarin or other anticoagulant poisoning is suspected, samples of liver, kidney, stomach content, feed, heparinized whole blood, blood found in body cavities, and formalinized tissues should be sent. In most cases, a complete diagnostic examination is necessary to establish the cause of death. Therefore, the samples for histopathology should include brain, lung, heart, liver, spleen, kidney, urinary bladder, gastrointestinal segments, and samples of any organ with gross lesions. In addition, brain, lung, liver, spleen, kidney, and any organ with lesions should be submitted refrigerated for culture for bacteria and viruses.