July 2019

Over the Counter Illicit Drug Screens in Companion Animals

By Dr. Scott Fritz

The Toxicology department at KSVDL fields questions on a large variety of toxicant exposures. Companion animal calls are generally centered on rodenticides, acetaminophen, NSAIDS, ethylene glycol, consumption of human drugs, and topical parasiticides. One class of exposures that is becoming more common is illicit human drugs (drugs of abuse).

Tetrahydrocannabinol (THC) poisonings are becoming commonplace after the recent legislation legalizing marijuana in certain states. Less common cases include amphetamines/methamphetamines, opiates, barbiturates, cocaine, phencyclidines (PCP), methadone, and benzodiazepines.

Drug Class
Barbiturates, Benzodiazepines, and THC Depressant
Amphetamines and Methamphetamines Stimulant
Opiates Analgesic
Cocaine Initial stimulation followed by depression
PCP Dissociative

Cases of exposure in companion animals – mainly dogs - can be difficult to diagnose. Dogs exhibit clinical signs similar to their human counterparts when exposed to these substances, and can be confusing to interpret. Another difficulty arising when diagnosing or managing these cases include owners who are unaware of exposure or are reluctant to provide an accurate history.


Gas chromatography/mass spectrometry (GC/MS) is the gold standard for identifying illicit drugs in humans and animals alike. GC/MS takes time and can be costly making it impractical in an emergency situation. Over the counter human drug screen kits take minutes to test urine. The kits can be used in animal patients and are useful on an emergency basis.

These kits are reliable for amphetamines/methamphetamines, barbiturates, opiates, and benzodiazepines. Tetrahydrocannabinol, cocaine, and PCP results are unreliable when using these kits.

Please keep in mind that like many other tests, there are a number of compounds that can cause false positive results. The kits are cost effective, fast, and reliable when used for the aforementioned substances and can be a vital tool in a practitioner's arsenal.

Dr. Scott Fritz is a Toxicology resident in the Kansas State College of Veterinary Medicine.

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