A new study by researchers at the University of Pennsylvania’s Perelman School of Medicine and the School of Veterinary Medicine reviewed all opioids dispensed at the veterinary school for dogs, cats, and other small animals from January 2007 through December 2017.

The findings show that prescriptions rose 41% annually, while the number of patient visits rose only 13%.

The researchers found the ratio worrisome.

Veterinary prescription of opioids is not as heavily regulated as medical opioid prescription for humans, and the researchers say it’s possible that the misuse of veterinary prescriptions could contribute to the ongoing human epidemic because the relative ease of access could mean increased risk of diversion.

“As we are seeing the opioid epidemic press on, we are identifying other avenues of possible human consumption and misuse,” said study senior author Jeanmarie Perrone, MD, a professor of emergency medicine and the director of medical toxicology at the Perelman School of Medicine. “Even where the increase in prescribed veterinary opioids is well intended by the veterinarian, it can mean an increased chance of leftover pills being misused later by household members, sold or diverted, or endangering young children through unintentional exposure.”

The researchers reviewed pharmacy records at the veterinary school’s Ryan Hospital during the 10-year study window and analyzed trends for the four opioids prescribed or dispensed to animal patients—tramadol, hydrocodone, and codeine tablets, and fentanyl patches. Of the animals receiving some form of opioid, 73% were dogs, 22% were cats, and 5% were assorted other small pets including rabbits, snakes, and birds.

“The results of this study suggest that by assessing the rate of veterinary opioid prescriptions, we can develop strategies to reduce both human and animal health risks associated with increasing use,” Perrone said.

Drug overdose deaths in humans have tripled since 1999, and prescription opioid deaths have quadrupled, according to data from the Centers for Disease Control and Prevention.

Although there are no hard figures on veterinarian-prescribed opioids being used by people, the possibility alone has prompted legislative action by some states.

Maine now requires background checks on pet owners’ opioid prescription histories before a veterinarian can write an opioid prescription, while Colorado has guidelines in place that strongly recommend it. Alaska, Connecticut, and Virginia now limit the amount of opioids any one veterinarian can prescribe to a single patient. And 20 states now require veterinarians to report their opioid prescriptions to a central database, just as medical doctors do.

And at least one study indicates that despite the current opioid epidemic, fears of pet owner “doctor shopping” and the resultant increased availability of veterinary-prescription opioids may be less common than some fear.

The authors of the University of Pennsylvania study also note that because the university veterinary school is a referral facility, it’s “Unique caseload requires particular attention to and treatment of pain in veterinary species, which may account for increased opioid utilization in the study.”

So until the profession knows more about the potential or extent of prescription diversion from animals to humans, and what effect it might have on the human opioid crisis, it’s very much a case of better safe than sorry.

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