Flea Allergy Dermatitis: Symptoms and Treatment for Dogs

One of the first signs that you dog has fleas is the frequent scratching.  This is a natural reaction to a flea crawling about on its skin.  For some dogs however, the scratching can take a more serious turn.  One of the complications fleas trigger is flea allergy dermatitis (FAD).  If you suspect that your dog is a victim of FAD you need to act before the condition gets out of hand.

Flea allergy dermatitis needs swift treatment to prevent your dog suffering discomfort. Photo Credit: annankkml/FreeDigitalPhotos.net

This post deals with:

  • What causes flea allergy dermatitis;
  • The symptoms of flea allergy dermatitis;
  • The treatment of flea allergy dermatitis.



The Causes of Flea Allergy Dermatitis

Flea allergy dermatitis (FAD) is caused by the bite of a flea.  It’s a common condition, but it doesn’t affect all dogs.  Those dogs that get FAD are allergic to the saliva in the flea’s bite.  The allergic reaction makes the dog’s skin extremely itchy and it scratches incessantly often causing the skin to break.  This can allow secondary skin infections.

Not all dogs will develop FAD; you may have two dogs in the same house one of which develops the problem, whilst the other one doesn’t.  Some dogs can be infested with fleas and not have FAD, others may have only a few fleas and develop FAD.  There isn’t a type of flea that causes FAD, it is that the dog has a predisposition to FAD.

The Symptoms of Flea Allergy Dermatitis

The number one indicator of FAD is going to be excessive scratching, nibbling and grooming.  These don’t necessarily mean FAD (we will look at other problems that cause itching and scratching in a future post), but it should set your alarm bells ringing and get you to investigate further.

A note of caution.  Don’t look for fleas on your dog and think that an absence of fleas means he can’t have FAD.  For one thing, it is always difficult to spot fleas on a dog.  In the case of a dog with FAD it can be doubly hard.  Because he is grooming so much he can often remove all evidence of fleas.

Flea Allergy Dermatitis Symptoms:  This is what you should be looking for:

  • Licking, nibbling and chewing around the base of his tail, his rump,  the tops of his back legs and even down his front legs.
  • Broken hairs from nibbling and wet patches from licking.
  • Lesions on his skin.  If you part his fur and look at his skin you may find oozing sore spots, caused by licking and biting his skin.
  • Red bumps (papules) on the skin.  (Run your fingers gently over his skin to find them.)
  • Thickened patches of skin.
  • Fur missing; the dog has pulled it out through chewing.
  • “Hot spots” which are areas of skin inflammation and infection.   The area will be red, often oozing and intensely itchy.    These will typically be on the back, near the rump and occasionally around the face (from scratching with the back legs).

At the first sign of FAD you should take action to treat your dog.  There are plenty of photographs on the internet of dogs whose FAD has gone untreated.  They look horrific; imagine how the dog must feel.  Take action before your dog develops hot spots; investigate as soon as he starts grooming excessively.  If you fail to treat FAD you will have a miserable dog and treatment will involve the vet, along with his bills.

Treatment for Flea Allergy Dermatitis

The first thing you need to do is to get rid of the fleas on your dog.  In order to eradicate the fleas quickly I would use a tablet that kills them within 24 hours.  This would be in addition to a spot-on treatment that would take care of fleas in the long term.  You would also need to control fleas in your house.

Removing the fleas should stop any further biting and stop the FAD becoming a prolonged problem.  The next step is to treat your dog’s skin and alleviate his existing discomfort.

If he is just itchy with minor skin irritation and no sign of infection, use a gentle, soap-free hydrating shampoo.  Sebocalm by Virbac (called Epi-Soothe in the US) is ideal; it is hypoallergenic and leaves a protective film on the dog’s skin.  My dog’s skin sees a positive improvement immediately on using this product.

Also recommended for minor FAD is aloe vera.  Find a product that is 100% pure aloe vera and apply it topically to any itchy areas.

Should your dog have more serious FAD, with a hot spot for instance, you will need to see your vet.  Often he will need a steroid injection, a course of antibiotics or perhaps a spray or cream.

If your dog has FAD he will always have FAD so you will need to be extra vigilant in keeping on top of fleas.  Even a few bites will set off the allergic reaction, so you must ensure that you keep your dog and home flea-free.


  • Some dogs’ immune system makes them allergic to flea saliva.
  • Investigate excessive scratching and grooming early.
  • Eradicate fleas at the first signs of FAD and don’t allow the problem to escalate.
  • Treat FAD yourself in the early stages if it is minor.  Consult your vet if it becomes more serious.
  • A dog with FAD will always have FAD; practise a rigorous system of flea control for your dog and your home.


Photo Credit:  annankkml/FreeDigitalPhotos

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