It can certainly be the case that your dog has fleas without you being able to find one of these tiny, sneaky critters.
Dogs that are sensitive to fleas will often groom any sign of fleas from their coats i.e. they will groom the fleas and the flea dirt out of their coats. However fleas could still be breeding and dropping thousands of eggs into the environment.
Flea dirt is essentially flea poop! A good way to check for fleas is to look through your dog’s coat to see if you can see anything that looks like curly dirt. This can look very similar to normal dirt, but a good way to check is to wet a piece of white tissue paper and smudge the dirt onto this. Flea dirt is blood, so you see a pink stain to the tissue paper.
If your dog is chewing itself or grooming a lot, especially around its tail or back end, fleas are by far the most likely diagnosis. Dogs that are sensitive to fleas will often groom themselves so much that they start to lose hair. This is often worse around the tail base.
Dogs will not always overgroom or chew themselves if they have fleas. This can make it really difficult to tell if your dog has fleas.
Allergy to the flea saliva is one of the most common skin allergies and this will usually make your dog very itchy.
Regular flea treatments are recommended and in hot and humid (perfect for fleas) climates, treatments should continue through the winter as well. All flea treatment products are not created equal, and the efficacy of some products is not great as they only last for a couple of hours after application!
Therefore, when the flea eggs inevitably hatch, the fleas just jump back on your dog. Ask your veterinarian to provide the correct product for your pet, but Frontlineand Advantix are excellent products.
In my opinion, the best product on the market for fleas is Comfortis which is a monthly tablet. This will kill all fleas on your dog within 2-4 hours and will last all month. Note that Comfortis is not registered for tick prevention however, so if you live in an area where Tick paralysis is a concern, Advantix or Frontline every 2 weeks in the tick season is crucial.