Help! My Cat Has Fleas! (Vet Answered)
This question has been answered by a vet
Veterinarian & Animal Behaviorist
With nearly two decades in veterinary medicine, Dr. Paola brings hands-on experience across multiple species. A graduate of the University of Guadalajara, she specializes in preventive care, animal welfare, and positive reinforcement training.
The Question
“Dear Dr. Paola,
Recently, my cats, Peach and Birdy, contracted fleas, probably because our back yard is like a train depot for squirrels, possums, and other cats. I’ve even seen a rat out there!
Anyway, I had previously covered them both, effectively, with Soresto flea collars, but my vet says that collars aren’t effective for flea control. They suggested a prescription topical med that they will need every month instead of a collar every 7 months.
I had inadvertently let their collars go over the effective range; that’s why they got fleas. Can I have your thoughts on collars vs topicals?“– Tuth
Quick Info about Peach and Birdy
Hi Tuth,
Thank you for sharing your experience. It sounds like you’re navigating a very common but frustrating challenge, especially in a backyard that’s essentially a crossroads for wildlife. Fleas thrive in these environments, and cats that spend any time near these high-traffic zones are at increased risk. You’re absolutely right that efficacy often comes down to timing and consistency, which is where many products, even good ones, can fall short if they’re not maintained on schedule.
The Seresto collar has been widely used and, for many pets, has provided effective flea control through its sustained release of imidacloprid and flumethrin. However, safety concerns have been raised in the past few years. The U.S. Environmental Protection Agency (EPA) received tens of thousands of adverse event reports, including over 1,700 pet deaths allegedly linked to the collar. Although the EPA and the manufacturer have stated that no direct causal link was confirmed and that most incidents involved mild skin reactions, the volume of reports led to increased scrutiny, updated warning labels, and a voluntary withdrawal from the Canadian market.
These concerns, paired with the possibility of decreased effectiveness as the collar nears the end of its active period, have prompted many veterinarians to prefer monthly prescription preventatives. Topical prescription treatments, like those containing fluralaner, selamectin, or imidacloprid combined with moxidectin, tend to be more consistent in maintaining therapeutic levels across the skin because they are reapplied monthly and are less affected by outdoor exposure or grooming habits. These medications also often target multiple life stages of the flea and may protect against other parasites like mites or intestinal worms, depending on the product.
In terms of efficacy and resistance management, many veterinarians lean toward prescription topicals or orals for more dependable control, especially in high-risk environments. That said, if a pet parent is diligent with collar replacement and the pet tolerates it well, collars like Seresto can still play a role. What’s most important is selecting a product that fits your lifestyle and sticking to a strict schedule.
I hope this helps!
Dr. Paola