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Itchy dog with fleas scratching

The essentials

  • FAD stands for flea allergy dermatitis — This itchy condition is caused by hypersensitivity to antigenic material from flea saliva.
  • Watch for classic FAD signs — Pet owners may notice their furry friend is restless and uncomfortable and a vet appointment may be needed.
  • The FAD clinical signs may worsen as pets age — The signs also persist and last longer! It’s especially important to prevent fleas from biting your senior dog.

If your pup has picked up fleas and seems itchier than usual, there’s a strong chance they’re suffering from flea allergy dermatitis (FAD).

Below we’ll cover everything pet parents need to know about FAD and how to prevent it.

What is flea allergy dermatitis?

Flea allergy dermatitis (FAD) is caused by hypersensitivity to a flea bite and the saliva injected by fleas during a bite.

FAD is one of the most common illnesses associated with flea infestation in dogs and cats and often includes itching, fur loss, and inflamed skin. A dog with FAD may suffer from just a few flea bites or even a single flea bite.

Clinical signs of FAD

The top signs of flea allergy dermatitis are itching, licking, and intense biting of the skin.   Other common signs look like:

  • Small, raised lesions on the lower back, tail, head, and inner thighs
  • Obvious restless and uncomfortable behavior
  • Scratching, licking, rubbing, chewing, and even nibbling at the skin
  • Hair may be stained brown from the licking
  • Sores or scabs and crusty, oozy skin
  • Presence of fleas or “flea dirt” on the skin
  • Unpleasant odor
  • Hair loss

Generally, the areas affected include the rump and tail, hind legs as well as areas of the head. Pet owners will also see itching and hair loss in the region from the middle of the back to the tail and down the rear legs (also known as the “flea triangle”). Some dogs may even have visible bite marks on their skin.

What if I don’t see fleas on my dog?

Just because you don’t see the fleas on your furry friend, doesn’t mean they aren’t there. Fleas are small and can be easy to miss, especially on dogs with dark fur. Fleas leave behind “flea dirt” or dark specs that look like black pepper. So if you don’t see fleas, this is a good sign to look out for.

Diagnosing flea allergy dermatitis in dogs

Vets will look for evidence of fleas or flea dirt on a dog’s skin when they examine the canine to determine if this parasite is the cause of the allergic response.

In addition to inspecting more obvious sights of FAD, vets will also consider an intradermal test (ELISA) and skin biopsy to confirm.

Diagnosing secondary infections

It’s common for a dog’s skin to develop a secondary infection with FAD. In these cases, a vet will use cytology to diagnose any other skin infections.

Your vet will typically collect a surface sample from a skin lesion using something simple like a piece of tape or pressing a microscope slide to the skin’s surface to gather matter for diagnostic skin tests.

Treatment for FAD

Fleas are becoming resistant to topical flea and tick preventatives, such as Frontline, Advantix, and Effitix. Therefore most vets will recommend an oral treatment product.

That being said, some topical flea/tick products may provide some repellent qualities whereas oral products can’t. If your dog is prone to fleas, your vet may recommend putting them on a comprehensive oral medication, along with a flea-repellent collar like Seresto for extra protection.

👉 Flea shampoos may kill adult fleas, but they won’t stop eggs from hatching, so these aren’t considered an effective method for treating fleas on your pet.

Treating with oral medications

Vets recommend the following combination of oral preventives for dogs and one topical for dogs with food allergies:

  • Sentinel Spectrum and Simparica monthly year-round. This combination protects your dog against heartworms, roundworms, hookworms, whipworms, tapeworms, fleas, and ticks. Simparica also has the fastest flea/tick kill compared with other flea/tick preventatives.
  • Simparica Trio is multifaceted. Is an oral monthly preventative that protects against heartworms, fleas, ticks, roundworms, and hookworms.
  • Trifexis is an oral monthly preventative. This medication protects against heartworms, fleas, hookworms, roundworms, and whipworms. There is no tick prevention with this product.
  • For dogs with food allergies use Revolution. This topical is the safest option to use as it is a topical that is applied monthly for the prevention of fleas, heartworms, roundworms, and hookworms. (This topical is an exception because of the food allergy issue).

Skin treatments for irritation

For mild itching with FAD, over-the-counter topical sprays that have hydrocortisone can be used for several days to help control itching. Benadryl can also be used as an OTC treatment in mild cases. However, always check with your veterinarian for dosing instructions and to make sure this medication is safe for your pet.

Corticosteroids, most commonly prednisone, are widely used to treat acute episodes of extremely itchy FAD. However, while steroids can bring about almost miraculous relief from the itching, they have significant side effects and should only be used as a short-term treatment for FAD. Many of today’s oral treatments, like Cytopoint and Apoquel, also help address itching and inflammation without the use of steroids.

Your veterinarian will discuss the pros and cons of the various treatments for FAD with you during the examination and will recommend the safest and most effective treatment for your pet’s needs.

👉 Whenever you give something new to your dog, watch them closely for 24-48 hours. Call your vet if you notice any hives, vomiting, or diarrhea.

Prevent fleas from biting your dog

The most important tip for pet owners is to give your dog a monthly flea control medication. Many effective long-term flea control medications will prevent fleas from reproducing.

Once a flea infestation is eradicated, most pet owners stop administering flea products. Instead, all pet owners need to talk to their vet about a monthly flea control medication year-round.

Also, it’s important for all pets (dogs and cats) in the household to be on flea prevention. Talk to your vet about flea preventatives for cats as they are different from dogs.

Long-term monthly treatments

Pet owners should have their vet prescribe a flea/tick prevention medication for their dog and also treat for itchiness with either Apoquel (oral medication) or Cytopoint (injection). Your vet can talk to you about the best monthly treatment for your dog.

Flea sprays to help with the environment

There are sprays to help eradicate fleas from bedding, the yard, and furniture. Pet owners can spray carpets and hardwood floors. Treating the areas of the yard your dog spends a lot of time in will also help eliminate fleas.

Knockout spray is the best option to eliminate fleas from the environment. Also, it’s important to wash any bedding in the washing machine and vacuum your home thoroughly to eliminate as many flea eggs as possible.

Shampoos to soothe skin

An oatmeal shampoo like Douxo Calm can be used to help soothe your pet’s skin but shampoos are often not needed as long as the fleas are treated quickly with oral flea/tick prevention. If you’re using a flea shampoo remember that any medicated shampoos can strip topical flea prevention products away.

No matter what climate you live in, fleas are a year-round problem and your vet will typically recommend a monthly flea control medication to protect Fido regardless of the season.

If you notice your dog itching, licking, or excessively biting at their skin, this may be an indicator your dog has FAD. Pay attention to other warning signs like skin lesions, scabs, and loss of hair, and take your pup to the vet for a professional diagnosis and treatment.

Frequently asked questions

How do you treat flea allergy dermatitis?

Since the injection of flea saliva causes the allergic response associated with FAD, it’s important to get to the root of the cause for treatment and prevent fleas from biting your dog. Even if you don’t see fleas on your dog, consistent flea control is essential for treating and preventing FAD. After eradicating fleas with an oral treatment, you’ll need to treat the skin irritation.

In mild cases, Benadryl can provide some relief. However, most dogs with FAD need more help beyond over-the-counter medication. Talk to your veterinarian about the need for steroids or other allergy meds such as Apoquel or Cytopoint.

How long does flea dermatitis last?

Once fleas are controlled it can take up to two weeks after a bite for your dog to stop itching. If a rash has developed on your pet’s skin or they have raw, irritated, or bleeding areas on their body, it can take significantly more time for those lesions to heal.

Can you have flea allergy dermatitis but no fleas?

The absence of live fleas doesn’t rule out FAD. A dog can experience FAD with a single bite, depending on how sensitive their skin is to a flea’s saliva. Some dogs experience a more adverse reaction than others.

Is flea allergy dermatitis an emergency?

Flea allergy dermatitis is not a life-threatening emergency. However, it is extremely uncomfortable for dogs. Severely itchy dogs often show signs of distress and are unable to sleep well or get comfortable. If you notice signs of FAD, be sure to get your dog to a veterinarian as soon as possible for treatment.

What does flea dermatitis look like?

If your dog has flea allergy dermatitis, their skin will appear red, be mild to severely itchy, and may have bumps, crusts, or lesions.