Flea Allergy Dermatitis

itchy dog, flea allergy dermatitis, flea allergies in dogs

It can be one of the most frustrating conditions for dogs and cats, as well as their owners: itchy skin. With the background sounds of continuous licks, chews, scratches, and the associated collar jewelry jingling, you know your pet is more than uncomfortable.

Flea allergy dermatitis can be just as frustrating to vets, as many pet owners have a difficult time believe their pet has fleas or this condition. In actuality, when a pet is affected by flea allergy dermatitis (or flea bite allergy, as it is often referred to as), your dog or cat doesn’t even have to have fleas to be affected.

So what is it then? Flea allergy dermatitis arises from a negative immune response to flea saliva resulting in subsequent skin lesions and intense itchiness. In dogs, it is most common in dogs that are at least 3-years old, and rarely less than 6 months old. It can be a seasonal disease, but as some homes have indoor fleas present, it is often continuous problem.

With many dogs now visiting dog parks, pet stores, or even pet-friendly restaurants, it is virtually impossible to avoid fleas. Even if your pooch came from the most reputable breeder and remains in pristine condition, it is not a negative indicator of the care you provide your pet if your vet suspects your dog or cat suffers from flea allergy dermatitis.

Clinical signs of flea allergy dermatitis in dogs include moderate to severe itchiness, papules (small red bumps), overall redness, self-trauma from biting and scratching, hair loss, scratched or wounded skin, increase in skin pigmentation, and dandruff. The base of the tail, over the back, the backs of the thighs, and the front legs are common locations to see signs in dogs. In cats, head and neck itching, red lesions on the abdomen, small bumps and scabs, and symmetric alopecia may be seen. Fleas or flea dirt (black tiny specks in the fur that are actually flea feces and become red upon wetting with a water drop) may or may not be seen.

Hypersensitivity reactions to the flea saliva happen as the pet’s immune system is exposed to the saliva antigens repeatedly and over time. This is why a very young puppy is much less likely to be affected by this condition than an older dog. Even if your pet does not “have fleas” all it takes is one flea to jump on them and bite once. Even with religious use of flea preventatives, it is nearly impossible to keep this from happening if your pet leaves the house.

ask a vet, online vet reviews, online vet, pet medicationsWhere does this leave you if your pet has these symptoms but you’ve never seen a flea? Your vet may recommend treating for fleas before delving into other expensive tests. This is partly up to you as the owner, but it is not unreasonable, and may be considered wise to invest here before spending hundreds of dollars on advanced intradermal or blood testing. A diagnosis from the vet is based almost entirely on history and physical exam findings. Even in the absence of fleas or flea dirt, physical exam findings consistent with these described warrant flea treatment with or without other testing for other causes of itching skin.

Just as important to the treatment plan as preventing fleas is relieving your pet’s pain and extreme itchiness. A low dose of steroids, topical sprays, and even oral antibiotics may be needed. Most likely, there is a generic medication dose available that will work with your pet that you can purchase at one of the providers of the $4 prescription program, such as Target or Wal-mart. Yes, your vet can (and is obligated to) provide you with a prescription to purchase your pet’s medications elsewhere than your vet. This can bring your spending down from hundreds to $4.

As for flea medications, we have all seen ads and heard of the standards: Frontline Plus, Advantix, Comfortis, etc. The choice that is the best for you and your pet really does depend upon what part of the country you live in, as different bugs thrive in different climates, and your pet’s individual needs. They are really all great products, and are very well tolerated when applied as instructed.

Here is an example of a product that not only kills fleas, but also the eggs so that an infestation can be better treated/prevented:

Not a fan of the chemicals in these products? While I have had strong success with them, many people are turning to “natural” solutions. Sprinkle a thin layer of borax powder (found in your grocery store’s laundry section) on your floors, leave to set, and later sweep up the excess. Bonus points if you can designate an inexpensive broom to this task. Make sure you have blocked off the area from pets and children, and that you wear gloves and are not barefoot. The powder works by making holes in the fleas’ exoskeleton, thereby killing them. The downside is that it is a little messy, can be caustic to your skin, and is more effective if left down for 24 – 72 hours. It does require some planning but is a great alternative for those looking to go to extra lengths to ward off fleas.

With many dogs now visiting dog parks, pet stores, or even pet-friendly restaurants, it is virtually impossible to avoid fleas. Even if your pooch came from the most reputable breeder and remains in pristine condition, it is not a negative indicator of the care you provide your pet if your vet suspects your dog or cat suffers from flea allergy dermatitis, which unfortunately there is no cure for. If you have have any questions about your pet’s health or a diagnosis from your vet, we are here for you and your beloved pet 24/7.

Dr. Laci


Dr. Laci Nash Schaible, DVM

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February 4, 2011 at 14:17

Fingers crossed our terrier has never had fleas.

We take him to the local vets in kent every now and then for a check up.

So far hes very healthy and happy!

February 6, 2011 at 12:01

I am often faced with clients that don't believe we even have fleas in our neck of the woods, much less there precious fluffy getting them.  I would like to point out that if your pet has come across fleas it says NOTHING about how clean your house or pet is.  They are mobile parasites and you should be more worried about treating than you are about if they exist.
Personally I have had good luck in my region with monthly treatment of frontline for 3 months and then every other month treatment.  If the pet starts to itch again after reducing the medication then we go back up to monthly.  That said our flea population is smaller than  many places and is why we can reduce the medication sometimes.

February 7, 2011 at 18:01

Hi Dr. Shaw,

Thanks for reinforcing it to clients that it doesn’t reflect upon the cleanliness of health of the home / pet.

Personally, we have been lucky enough to go every other month with our indoor only cats, but not with our dogs. Then again, they go to the hospital everyday where you know what all comes through the door!

Thanks for commenting.

February 8, 2011 at 02:29

The idea of my dog having fleas would make me feel bad about myself as an owner. I think no matter how many times you can tell me it’s not my fault, I would still feel it is :-)

February 8, 2011 at 11:47


At least know that vets won’t judge you–not that that matters at all, but as a group, we’ve got to be up there with groomers for who sees the most fleas and our verdict is not guilty!

I remember the first time as a vet I found a tick embedded in my scalp. At that point, I was longing for a tick collar to wear around my ankle or some place less necklace-like. These things happen as we–pets and pet people– are in the line of fire, or creepy crawlies.

July 30, 2012 at 08:22