Becoming a veterinary detective

There are many great detectives, fictional and nonfictional, solving crimes and keeping their communities safe—much like veterinary professionals. Each day, a “mystery” presents itself at clinics across the country: pets vomiting worms, dogs that will not stop itching, cats eliminating outside the litter box, and more. It is up to the veterinary team to solve the case and get justice—or, as they would call it, a treatment plan.

In his keynote address kicking off day 2 of Fetch Charlotte, Christopher Lee, DVM, MPH, DACVPM, DACVM (Parasitology), invited attendees into the world of parasitic cases to help determine the crime, the motive, and the correct “sentence” for the crimes in question.

Set the scene

To begin the investigation, Lee invited everyone into the Clinical Crimes Division (CCD), where Detective Canis Holmes, DVM, and Felina Watson, DVM, MSc, DACVM (Parasitology), are greeted by socialite Madame Bijou, a 3-year-old female intact standard poodle. Madame Bijou is in the CCD because she vomited a worm that morning. She asks the detectives whether she can just receive a vaccine and something to treat the worm so she can be on her way. However, although it seems like a straightforward request, it places veterinary professionals at a crossroads to determine whether they should merely "treat the moment."

After discussing the worm, Lee asked the audience whether the next step should be a fecal exam. He agreed with those who raised their hands, but he followed up with more questions: Do we run it in-house? Do we send it out? Is it a direct smear? Sedimentation? Centrifugation? What about polymerase chain reaction (PCR)?

“PCR is always awesome. Anytime we can run PCR, it is great. We want that fecal because we don’t know [the full story]. We want to make sure we know who the culprit is, and maybe they have friends. Some people said they would not necessarily run a fecal, and I don’t think that is necessarily wrong either,” Lee said to attendees. “A lot of my work has been with a low socioeconomic status clientele base, and they’re like, ‘I love my dog; I can either deworm her or do the fecal you want.’

“So again, there are a lot of right ways of doing this. What about vaccines? Do we give them?” he continued. Lee then told the audience that the detectives identified the worm based on testing: Toxocara canis.

The case

For this infection, Lee explained that the clinical goal is to not only kill the adults but also reduce the chance of future contamination and human exposure. Regarding the life cycle of T canis, Lee noted that transplacental transmission is a key route for puppies, whereas older dogs more commonly develop somatic larval arrest, leading to less frequent patent infections.

For dogs, especially young ones, Toxocara spp infections are common, but they pose a significant risk because they are zoonotic. The detectives then needed to do a “quick sweep“ of Madame Bijou’s house to assess the threat she poses to children in the home or anyone immunocompromised, as well as her sanitation routines and dog park habits. In this case, deworming is appropriate; however, prevention plans reduce a pet’s chance of reinfection and environmental egg shedding.

Toxocara spp infections also lay a trap for veterinary detectives: the “one and done“ approach. Lee said to avoid this trap because it has the potential to teach clients that episodic treatment is a sufficient plan.

Sentencing

The case of Madame Bijou is just 1 of several cases Lee presented during his address. Although it is an entertaining way to present a lecture as a "play-along" detective game, Lee warns that parasitic cases are rarely simple. Each time they enter the veterinary clinic, parasites are often the first visible clue to a much larger problem that can lead to exposure risks, preventable coinfections, problematic client behavior, and One Health implications. Understanding these risks will ensure your patients receive only 1 life sentence: prevention.

Reference

1. Lee C. CSI: Canine scene investigation: cracking the case in veterinary medicine. Presented at: Fetch Charlotte 2026; March 13-14, 2026; Charlotte, NC.