AVMA 2017: Recognizing and Reporting Adverse Drug Events

July 23, 2017
Nicola M. Parry, BVSc, MRCVS, MSc, DACVP, ELS

Adverse drug events are inevitable in veterinary patients, and it’s imperative for veterinarians to know how to identify them and understand the importance of reporting them.

Veterinarians’ understanding of adverse drug events (ADEs) has increased significantly in recent years, according to Cynthia Cole, DVM, PhD, DACVCP, general manager at Mars Veterinary and adjunct professor at the University of Florida in Gainesville.

Presenting at the American Veterinary Medical Association Convention in Indianapolis, Indiana, Dr. Cole noted that the World Health Organization defines an ADE as “any untoward medical event that may occur during treatment with a pharmaceutical product, but which does not necessarily have a causal relationship to that product.”

More specifically, an adverse drug reaction (ADR) is a type of ADE that occurs in response to a drug, is noxious and unintended, and occurs at normal doses used for prophylaxis, diagnosis, or treatment of a disease or modification of a physiologic condition.

However, it can be difficult to determine whether an ADE is an ADR, she added, so the two terms are often used interchangeably.

Because all drugs have the potential to cause ADEs, clinicians should be aware of how ADEs may present—particularly because they play a key role in recognizing ADEs.

In humans, rash is among the most commonly occurring signs that may indicate an ADR, Dr. Cole said. But many other signs are also possible, including fever, diarrhea, seizures, or anaphylaxis, as well as changes in heart rate and respiratory rate. Indeed, any sudden, unexpected change in a patient’s status could indicate an ADR. Dr. Cole, therefore, advised clinicians to warn clients that if they see any reaction or change in their pet after administration of a drug, clients should contact their veterinarian immediately.

Larger studies correlating reports of ADEs after administration of veterinary medicines are lacking in the veterinary literature, said Dr. Cole. However, she shared findings from a 2014 study in Switzerland that evaluated 250 adverse reactions to veterinary medicinal products. The data showed that most ADRs were related to use of antiparasitic agents (46.4%) or anti-infectives (9.3%), and dogs were predominantly affected (n=144).

She encouraged clinicians to consider the risk:benefit ratio associated with using any drug before administering it to a patient. This balancing act is especially important when clinicians are considering using long-acting drugs, because once the drug is in the body it is difficult to eliminate it if an ADE arises.

“All drugs have side effects—we should expect that, we should accept it,” she said. And because ADRs tend to occur when a drug is reaching its steady-state concentration in the body, Dr. Cole stressed that clinicians should consider a drug’s half-life before administering it to a patient.

Dr. Cole also advised clinicians not to obtain all their information about a specific drug solely from a company’s drug representative. Data from objective research studies that are not funded by drug companies are valuable sources of information, she said, as are data from drug company—funded research that are available through the US Food and Drug Administration.

Dr. Cole emphasized that clinicians must report ADEs, either to the drug’s manufacturing company or directly to the US Food and Drug Administration. Owners may also make the report, she noted.

Failure to report an ADE may have negative consequences, said Dr. Cole. If an owner believes that a pet has experienced an ADE but the veterinarian declines to report it, the owner may decide to inappropriately distribute information about the ADE, via social media or online blogs, for instance. Often, this involves overreaction and sharing of misinformation, she said.

“Report ADEs,” Dr. Cole stressed to attendees, “you are an important part of the process.”

Dr. Parry graduated from the University of Liverpool, England, in 1997, and is a board-certified veterinary pathologist. After 13 years working in academia, she founded Midwest Veterinary Pathology, LLC, where she now works as a private consultant. She is passionate about veterinary education and serves on the Indiana Veterinary Medical Association’s Continuing Education Committee. She regularly writes continuing education articles for veterinary organizations and journals, and has also served on the American College of Veterinary Pathologists’ Examination Committee and Education Committee.