Veterinary Handbook

Toxicological testing in cats and dogs – general guidelines

Veterinary clinics are often confronted with a dog or cat with clinical signs suggesting exposure to a toxic substance. Clinical signs of many poisonings are similar and may be unable to be reliably differentiated on clinical grounds alone. A careful clinical history can often narrow the differentials. In some cases, owners are concerned that their animal has been deliberately poisoned and are seeking testing to confirm or rule out this possibility. Owners will often request a “toxin screen” in cases of suspected intoxication. Client communication and education is vital so that expectations of testing are not unrealistic. Toxin testing requires a specific toxin to be nominated as there is no suite of tests that covers all possibilities. Toxin testing is inherently expensive, requires specific sample types and false negatives can occur; for instance the toxin may have been eliminated from the body or be undetectable, but clinical signs may persist.

Awanui Veterinary can offer specific testing for a range of toxic substances, however it is important to consider the specific sample requirements and testing limitations for each toxin when advising your clients. Many tests are referred to external laboratories and may have extended turnaround times.

Specific toxin testing is NOT available for the following compounds: Fe-EDTA molluscicides, cholecalciferol based rodenticides, tick paralysis toxin, tetrodotoxin, lily toxin, amatoxin (mushrooms). Please contact the laboratory if you need testing for a specific toxin not listed here; we can often source unusual tests as needed from our network of referral laboratories.

General guidelines for sampling where toxin type is uncertain should aim to provide a wide range of samples for potential testing. Fresh tissue samples should be chilled or frozen for transportation to the laboratory.

Pre mortem sampling:

  • Suspected intoxicant (food, bait, water, medication)
  • Vomitus
  • Urine
  • Faeces

Post mortem sampling:

  • Fresh liver, kidney (ideally enough to fill a yellow-top pot, or the whole organ minus a small histology sample for smaller animals) 
  • Urine (yellow top pot) 
  • Stomach contents, small intestinal contents (yellow top pot)
  • Representative histological samples (the most important organs are liver and kidney, upper GIT). Remember formalin to tissue ratio should be at least 10:1 to allow adequate fixation.

Clinicians should also consider syndromes which may mimic intoxication such as hypocalcaemia, hypoglycaemia, hepatic encephalopathy, peripheral neuropathies and primary CNS diseases.

If litigation is threatened then you will need to:

  • Have a detailed record of all findings
  • Record the identity of the animal(s)
  • Collect and label specimens
  • Seal specimen containers
  • Maintain continuity of possession
  • Obtain a receipt of specimens.

Examples of intoxicants that can be tested are provided below. See individual tests for sample requirements. 

Biological control agents

  • Carbamates
  • Metaldehyde
  • 1080 (sodium fluoroacetate)
  • Strychnine
  • Synthetic pyrethroids
  • Organophosphates
  • Organochlorines
  • Anticoagulant rodenticides (warfarin, pindone, coumetetryl, bromadiolone, difenacoum, brodifacoum)

 Heavy metals

  • Arsenic
  • Lead

 Human medicinals

  • Paracetamol
  • Aspirin
  • Drugs of addiction (opiates, sympathetic amines, benzodiazepines, cannabinoids, barbiturates, cocaine, methadone)
  • Antidepressants (Amitryptyline, tricyclic antidepressants)
  • Phenobaritone, pentobarbitone

 Biological toxins

  • Cyanobacteria
  • Botulism
  • Mycotoxins