Signs of Flea Bite Dermatitis on Dogs

The head and face often show signs of FAD.
i Felix 2 image by Westa Zikas from

Flea bite dermatitis, also known as FAD or flea allergy dermatitis, occurs when a dog is allergic to the proteins in flea saliva. The condition can appear severe, especially if the infestation is reoccurring. Understanding the signs of FAD makes it easier to promptly treat your dog and prevent further infestation.

Red Bumps

For a dog with FAD, a single flea bite can cause skin inflammation and a raised, swollen bump, similar to a mosquito bite. As your dog continues scratching and biting, these initially small red bumps can expand in size and swelling. Common areas for these spots to appear include the inner thighs, neck and head.

Hair Loss

As the flea infestation continues, your dog's constant scratching and biting causes his hair to fall out. Although this can occur anywhere on the body, the most common places for hair loss include his rear end, outer thighs, flanks and back. The irritated and broken skin tissue of a dog with FAD becomes unable to support hair growth. Proper flea treatment, therapeutic baths and proper nutrition will quickly restore your dog's hair.

Crusty Residue

Itching and scratching eventually breaks open your dog's skin. As your dog continues scratching the area, his nails or mouth deposit bacteria inside the open sores, leading to secondary bacterial infections. Scratching and biting reopens these sores before they have time to heal, leading to a crusty, scab-like residue that covers the infected area. Hair loss makes these patches of crusty patches more visible.

Smelly Skin

The constant scabbing and bacterial skin infections associated with FAD will give your dog's skin a greasy, flaky appearance along with a foul odor. Smell your dog's skin, and examine his body for patches fitting the above descriptions. Just like smelly ears or noxious stitches, any foul odor coming from your dog signifies the need for prompt veterinary care.

Always check with your veterinarian before changing your pet’s diet, medication, or physical activity routines. This information is not a substitute for a vet’s opinion.

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