Flea allergy dermatitis is a common and extremely frustrating problem in dogs and cats. It tends to occur in well cared for pets, which have had low-level intermittent exposures to fleas. In some pets, a genetic predisposition to overreact to flea bites occurs in much the same way that some people are allergic to bee stings.

Generally, these pets are not flea infested. In fact, it can be very difficult to find any fleas on these animals. This is because animals that are allergic have a delayed reaction to flea bites. This hypersensitivity reaction to even a single flea bite can cause extreme itchiness for 7 to 10 days!  Oftentimes, we witness the itching that occurs for the next week even in the complete absence of subsequent bites.

People are not appealing to fleas. As Dr. Jean Greek our local board certified Dermatologist likes to say “We humans taste like Brussels sprouts, whereas our pets taste like chocolate cake”.  Therefore, by the time we humans are being bitten by fleas, it typically means your pet’s environment has a major flea infestation. In fact, it is likely there are far more fleas than the tiny number needed to drive a flea allergic pet up the wall.

Most normal pets will have mild to moderate itching associated with flea infestation. This explains why sometimes a single pet in the household may have severe signs while others seem to be minimally affected. This is a true allergy, and these animals cannot tolerate any flea exposure!

Typical clinical signs in dogs include severe pruritus (itching) over the back to the base of the tail and in the groin. Dogs with other allergies will have a worsening of signs. Secondary bacterial skin infections causing rashes and scabs are very common. Flea allergy is the most common cause of hot spots.  (See Hot Spots information too).

Cats have more variable clinical signs. These may include any combination of the following: Over-grooming leading to hair loss with or without damage to the skin, crusting/scabs over the back, pruritus, and/or plaque/ulcerated lesions.

Diagnosis is usually made based on history and physical appearance of the pet.  Fleas or flea dirt (flea poop) support the diagnosis.  But, not finding fleas or flea dirt is not crucial to having a high index of suspicion as to their presence.  Often, the best way to make a flea allergy diagnosis is to aggressively treat for fleas and observe for improvement.

With the research and development of newer products, the safety of flea control treatments has improved tremendously. Scientists have developed agents which specifically target systems of the flea that are not present in dogs, cats and humans.  This makes toxic reactions extremely uncommon.

However, it is still very important to read product labels as there are products suitable for use in dogs that can be dangerous to cats!  Not all flea products are comparable.  And, cheaper is not usually better.

Although there are a number of excellent products on the market, Foothill Pet Hospital (FPH) feels it is important to ask your veterinarian or their staff which products they are currently recommending based on success, efficacy and safety.

Dr. Jean Greek, DVM, DACVD, Dermatology & Allergy Clinic for Animals.

If you have any questions or concerns, PLEASE FEEL FREE TO ASK US.