How Do I Know If My Pet Has a Flea Allergy?

Fleas are an extremely annoying and unfortunate nuisance to deal with if they invade your home. They are tiny pests and can multiply quickly in large numbers, making it even harder to control and get rid of. Even more unfortunate, your pet could have something called Flea Allergy Dermatitis, causing your pet to suffer more than other pets when bit by a flea. 

Flea allergies can be a very frustrating condition for you and a very uncomfortable condition for your pet. Thankfully, it is fully preventable and treatable! Flea Allergy Dermatitis, or FAD, is a leading cause of allergic reactions and the most common dermatologic disease in domestic dogs.

Keep in mind that not all pets are allergic to fleas. For the ones who are, however, the suffering can be extreme. 

In this blog, we will cover:

  • What a flea allergy is
  • Symptoms of a flea allergy in both dogs and cats
  • The danger of flea allergies
  • Diagnosis and treatment
  • Keeping your home clean from fleas

What is a Flea Allergy?

In an allergic reaction, the body’s immune system overreacts or is hypersensitive to a substance that is normally harmless, which usually causes itchiness. It’s not unusual for pets to scratch themselves, but everyday itching from a flea bite isn’t the same thing as a flea allergy. If your pet has FAD, the itching will be intense and last longer.

This disease typically appears between the ages of two and five, and pets with other allergies are more likely to be highly sensitive to flea bites and much more susceptible to FAD.

The allergic reaction occurs when a flea bites your pet, injecting their saliva into your pet’s skin. It’s the antigens in the flea’s saliva that cause an intensely itchy response for sensitive pets. The reaction can begin anywhere from 15 minutes to 48 hours after the bite. 

What Symptoms Should I Look for in Dogs? 

You may not see the fleas right away, or at all, but you will see the symptoms of the allergic reaction. For dogs with FAD, even one flea bite can cause a reaction.

Common symptoms of a flea allergy include:

  • Chewing and biting at the rear
  • Suddenly jumping up from a resting position
  • Intense itching
  • Skin hot to the touch
  • Skin flecked with scabs
  • Restlessness

Itching and hair loss in the region from the middle of the back to the tail base and down the rear legs (the flea triangle) is another symptom associated with FAD. If left untreated, the hair loss can spread all over the body, up to the head and neck.

What Symptoms Should I Look for in Cats?

Despite common belief, a normal cat experiences only minor skin irritation in response to fleabites, even if in the presence of dozens of fleas. On the other hand, a cat with flea allergies has a severe reaction to even a single flea bite.

While many of the symptoms are similar to a dog’s symptoms, there are a few differences that you should be aware of:

  • Intense itching of the skin, especially near the front of their tail
  • Constant chewing, licking, scratching
  • Scabs around the head and neck
  • Hair loss around the tail base, neck, and head

The Danger of Flea Allergies

If left untreated, your pet’s allergy can lead to hair loss spread throughout the body. In extreme cases it can even lead to infections.

Because they don’t know better, your pet will scratch, lick, or chew on the flea bite. This can cause open sores and scabs, and the moisture from the licking and chewing can lead to yeast and bacterial injections. 

Furthermore, if an infected flea is ingested as your pet grooms themselves, the larvae can develop into adult tapeworms in their intestines. Thankfully, treatment for tapeworms is simple and effective, but prevention is always preferable to treatment. 

Proper Diagnosis

The best way to properly diagnose your pet’s allergy is to first verify that fleas are present. It’s very common for pet owners to overlook them because they are so small! Fleas typically do not remain on the pet except for the minutes to hours when they are feeding. If you suspect that your pet is suffering from FAD, we recommend bringing your pet by PetWellClinic so that we can thoroughly check for fleas and flea dirt. 

Cats, on the other hand, can be such thorough groomers that it may be difficult to find evidence of fleas or flea dirt on the coat, especially if only one or two fleas are causing the problem. But don’t worry, we can conduct intradermal allergy tests or specialized blood tests to confirm a flea allergy.


At PetWellClinic, we are big fans of preventative medicine. Since the flea saliva causes the reaction, the most important treatment for flea allergy, especially for pets with FAD, is to prevent fleabites in the first place. Monthly oral flea preventives have made it easier and less expensive than ever to prevent fleas from affecting your furry friend. Other preventative options include topical medications or flea collars. Talk to your PetWellClinic veterinarian about which treatment is best for your pet.

Topical flea medicine is a popular and affordable option for rabies prevention

If your pet has already been bitten and is experiencing extreme discomfort, we will recommend a topical, oral, or injected medication to ease your pet’s itching and inflammation. We also recommend giving your pet a cool bath to soothe their skin and get off all of the dead fleas and their excrement. However, don’t use flea shampoo or other topical flea products without talking to us first as some include ingredients that could further irritate your pet’s skin. Your local PetWellClinic team will recommend what product works best for your pet’s specific needs!

After the fleas are gone, you still need to treat the skin irritation caused by the allergic dermatitis. In mild cases, you can treat your dog with Benadryl. However, always check with your PetWellClinic veterinarian for dosing instructions and to make sure this medication is safe for your pet. You should never medicate your pet with drugs or medicine made for humans without specific recommendations from your pet’s veterinary team.

Getting Rid of Fleas In Your Home

If your furry friend has fleas, it’s likely that a few of them have found their way into your home. Fleas reproduce quickly, and it only takes one to start an infestation in the home. Especially if you have carpet or rugs!

Preventing, reducing, and eliminating flea infestations in your home is crucial for your and your family’s comfort and health. 

To keep your home clean, we recommend that you regularly:

  • Vacuum all surfaces, especially areas where your pet sleeps
  • Wash your pet’s bedding
  • Wash bedding and rugs in detergent and warm water
  • Use flea spray on carpets and furniture if you know your pet has had fleas

There are times when flea infestations in the home go beyond simple cleaning or over-the-counter sprays. You may have to talk to a local exterminator if the infestation is too big for you to handle on your own. Just make sure if you have a professional come to spray for fleas, that you, your family, and all of your pets leave the home for the day. Only return when all of the fumes from the exterminator’s spray have subsided, and the fleas are dead.

Regularly vacuuming your home is a great way to prevent flea infestations

If your pet has FAD and is bitten by a flea, don’t worry! Our veterinarians will discuss the various treatment options with you during their examination and will recommend only the safest and most effective plan. Remember that prevention is essential, simple, and inexpensive. Ask your PetWellClinic veterinarian for the best flea prevention for your pet’s unique lifestyle and needs.

PetWellClinic is dedicated to being here for pet owners. Our hours of operation extend into the evenings and weekends, and our clinic environment is built with your pet’s comfort in mind. Did you know that we sell flea and tick prevention? If your pet is bitten by a flea and shows symptoms of an allergy, bring them to your local PetWellClinic so that we can discuss treatment options to help your pet feel comfortable. 

PetWellClinic provides convenient, affordable veterinary care for pet owners. PetWellClinic has locations and services built with convenience in mind. Stop by with your pet any time! No appointment necessary.

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