Immunoassay testing for barbiturates using alternative matrices in postmortem tissues from cats and dogs

Area of Science:

• Veterinary Forensics
• Toxicology
• Animal Health

Background:

• Pentobarbital is a common euthanasia agent for domestic animals.
• Determining chemical euthanasia status is crucial in veterinary forensic autopsies.
• Validated methods for barbiturate screening exist for urine, but alternative matrices are underexplored.

Purpose of the Study:

• To validate the use of alternative postmortem matrices for screening barbiturates in dogs and cats.
• To compare the efficacy of bead homogenization and sonication methods for sample processing.
• To assess the reliability of human immunochromatographic tests for pentobarbital detection in various tissues.

Main Methods:

• Postmortem heart, liver, spleen, skeletal muscle, blood, and urine samples were collected from 20 dogs and 26 cats.
• Samples were processed using bead homogenization and sonication techniques.
• Barbiturate screening was performed using a human immunochromatographic test, with a subset confirmed by gas chromatography-mass spectrometry.

Main Results:

• The sonication method achieved 100% agreement with reported euthanasia status for both species.
• Bead homogenization showed high agreement (93.3% for dogs, 96.7% for cats) but yielded some invalid results.
• Gas chromatography-mass spectrometry confirmed 100% agreement with immunochromatographic test results for canine and feline liver samples.

Conclusions:

• Sonication processing with immunochromatographic testing is a reliable method for postmortem barbiturate screening in dogs and cats.
• Alternative postmortem matrices (heart, liver, spleen, muscle, blood) can be effectively used when urine is unavailable.
• This study validates broader applications of immunochromatographic tests in veterinary forensic toxicology.