How do I know if flea and tick prevention is working?

A dog on working flea and tick prevention should consistently show a clean flea comb, no dark specks of flea dirt on a white surface, and no ticks found attached and feeding during regular checks, even after time spent in grassy or wooded areas.

Many flea and tick products work by killing the parasite after contact rather than repelling it entirely, so finding an occasional tick that attached briefly before dying, rather than one that fed for an extended period, can still be consistent with the product doing its job.

Finding live, active fleas, multiple ticks that appear to have fed for a while, or your dog showing new, persistent itching are all signs worth discussing with your vet, since this can mean the current product is not well suited to your dog, your region, or needs a dosage or timing adjustment.

During the months when fleas and ticks are most active in your area, jotting down a quick note each time you do a flea comb or tick check, even just a tally of how many you found, helps you and your vet spot a pattern of increasing exposure that might call for a product review.

Discussing your specific findings with your vet at the next routine visit, rather than only reaching out if something seems obviously wrong, lets them catch subtle patterns across several checkups that might not be obvious from a single visit alone.