The cause of death may not be determined despite a very thorough examination. A number of possible causes should, however, be eliminated. Postmortem examination and sample selection should take place as soon after death as possible.
If in doubt about how to proceed, please consult a pathologist at the AHL for sampling recommendations
A. Anesthetic deaths
These include deaths in previously healthy animals during induction of anesthesia, and in the immediate post-anesthetic period.
According to the Veterinarians Act, Regulations, 17.23, misconduct includes: "If an animal has died unexpectedly or from an anesthetic, failing to promptly inform the client about the availability of a necropsy through a veterinarian independent of the attending veterinarian but, having provided the information, the attending veterinarian or an associate, upon the client’s request, may perform the necropsy".
Body temperature recordings at the time of death may be helpful in ruling out malignant hyperthermia.
Accurate body weights and heart weights are needed to rule out myocardial hypertrophy, e.g., hypertrophic cardiomyopathy.
B. Previously healthy, found dead
Circumstances may indicate possible samples to submit. Rule-outs include:
All species: anaphylaxis, adverse drug reaction, bleed-out, electrocution (lightning), physical trauma (moving vehicle, self-trauma), gunshot, drowning, intestinal accident, botulism, septicemia (leptospirosis, salmonellosis), heat stroke, poisonous plants (Japanese yew), other poisons.
Horses - trauma, fractured skull or broken neck, aortic rupture, colitis, exercise-induced pulmonary hemorrhage, ruptured uterine artery.
Cattle - bloat, ruptured liver abscess, anthrax, blackleg, coliform mastitis, Histophilus somni, hypomagnesemia, lead poisoning, hypocalcemia, nutritional myopathy.
Pigs - edema disease, Glasser’s disease (Haemophilus parasuis), Actinobacillus suis, Actinobacillus pleuropneumoniae, Streptococcus suis, mulberry heart disease, porcine stress syndrome, gastrointestinal accidents, manure gas poisoning.
Sheep/goats - copper poisoning, clostridial enterotoxemia (“pulpy kidney”), septicemia (Bibersteinia trehalosi), bloat, including abomasal, in lambs and kids.
C. Suspected poisonings
Most such cases are not proven to be poisonings. Other causes of death (as in B above) should be ruled out before toxicology is undertaken. Known exposure to a toxicant would be useful; we can conduct a wide variety of assays, but have very few screening tests - a request to “check for toxins” is not adequate.
D. Submitting samples
1. Give a complete history, including number affected and number at risk, and when the animal was last seen alive.
2. Submit either the entire carcass OR conduct a routine postmortem, record your findings in detail and submit:
- Formalin-fixed samples for histology (brain, thyroid, thymus, lung, heart, liver, spleen, adrenal, kidney, pancreas, stomach, duodenum, jejunum, ileum, colon, urinary bladder, skeletal muscle); appropriate samples for bacteriology.
- In case of a suspected cardiac cause of death, submit the whole heart (dog, cat), OR after weighing the carcass and heart and dissecting the heart, weigh right ventricular free wall and left ventricle + septum, and submit sections of both atria, both ventricles, and septum. Remember that lung and liver are also very useful for histologic examination in cases of suspect cardiac failure.
- Freeze and hold tissues for possible toxicology [brain (for organophosphates and carbamates), liver, kidney, stomach content, fat, and, if available, serum, EDTA blood, urine].
3. Hold feed or water samples, if suspicious of either as the source of a toxicant.
4. Submit sample of suspected toxicant and/or its container.