Sudden or Unexpected Death in Animals

[Kvet Forum]

When an animal is found dead without having been previously observed to be ill, a diagnosis, even after necropsy examination, is often difficult because of the absence of a detailed history and clinical findings.

"All death is sudden, but the focus on an investigation of sudden death is that it was unexpected."

It is necessary to point out that there is a difference between “found dead” and “sudden and unexpected death.”

This list applies particularly to cattle.

1. SUDDEN OR UNEXPECTED DEATH IN SINGLE ANIMALS.

• Spontaneous Internal Hemorrhage: This condition could be caused by cardiac tamponade in cows, ruptured aorta or atrium, inherited aortic aneurysm, or verminous mesenteric arterial aneurysm in horses and esophagogastric ulcer or intestinal hemorrhagic syndrome in pigs.
• Rapture of Internal Carotid Artery Aneurysm: Condition may occur secondary to mycosis of the guttural pouch of the horse.
• Peracute Endogenous Toxemia: Can arise from rupture of the stomach of horses, abomasum of cows, and the colon in mares at foaling. Large amounts of gastrointestinal contents are deposited rapidly into the peritoneal cavity.
• Transportation Stress: This can result in sudden death in stress-susceptible animals. The best known example of this is porcine stress syndrome (PSS), during which stress appears to be the sole causative factor in death.
• Trauma: Causes death by either internal hemorrhage or damage to the CNS, especially the brain or atlantooccipital joint sufficient to damage the medulla oblongata.
• Gastrointestinal Conditions: Include: Gastric rapture, gastric impaction, peracute enteritis, bloat, volvulus (esp. in pigs).
• Iatrogenic Deaths: These may be caused by rapid administration or overdose with intravenous medications, anesthetics, fluids etc.

2. SUDDEN OR UNEXPECTED DEATH IN A GROUP OF ANIMALS.

• Lightning Strike or Electrocution: Usually affects a number of animals that are found together in a pile or group. History and an examination of the environment usually reveals the cause.
• Nutritional Deficiencies & Poisoning: May come from the sudden exposure of the cattle to plants that cause bloat, hypomagnesemia, cyanide or nitrite poisoning, fluoroacetate poisoning, microcystins(produced by algae in a stagnant lake or pond) etc.
• Access to Potent Poisons: A select number of herbicides, insecticides, rodenticides, and metals account for the majority of poisonings, with country to country variation and species differences.
• Diseases Associated with Infectious Agents: These diseases cause septicemia or toxemia, and include anthrax, blackleg, hemorrhagic septicemia. In pigs, mulberry heart disease and perhaps gut edema. In horses, colitis. In sheep and young cattle, enterotoxemia associated with Clostridium perfringens. Etc.
• Neonates and Young Animals: In very young, including neonatal, animals, congenital defects that are incompatible with life - prematurity, septicemia because of poor immune status or toxemia associated with particular pathogens, especially E. coli, and hypothyroidism - are important causes of sudden death.
• Anaphylaxis: Anaphylaxis after injection of biological materials, including vaccines and sera.

PROCEDURE FOR INVESTIGATION OF SUDDEN DEATH

• Take a careful history, which may indicate changes of feed composition or source, exposure to poisons, or administration of potentially toxic preparations.
• Make a careful examination of the environment to look for potential sources of pathogens.
• Carefully examine dead animals for signs of struggle, frothy nasal discharge, unclotted blood from natural orifices, bloat, pallor or otherwise of mucosae, burn marks on the body (especially on the feet), or signs of trauma or of having been restrained.
• Ensure that cadavers are examined at necropsy (post-mortem), preferably by specialist pathologists.
• Collect samples of suspect materials for analysis. Preferably, collect two samples, one to be analyzed and one to be made available when required.