Flea Allergy Dermatitis in Cats

There are a number of reasons cats can suffer with skin conditions, therefore it is not always easy for a veterinary surgeon to make definitive and swift diagnosis, without various tests. If you own a cat that has fur loss, is itchy and seems generally unhappy, one of the conditions they may have is feline flea allergy dermatitis.

What is flea allergy dermatitis?

Flea allergy dermatitis (FAD) is a form of skin hypersensitivity in cats (and it is also found, just as common, in dogs). It is a very distressing disease for the animal as well as the owner, who can only help their cat with guidance from their vet.

What causes flea allergy dermatitis?

Skin hypersensitivity is caused by exposure to flea saliva through flea bites. When a flea bites they inject their saliva into the animal. Flea saliva contains a variety of histamine compounds, enzymes and various amino acids amongst other things. When a cat is first bitten by a flea it will not cause any sensitisation, but after repeated exposure to flea saliva, the cat may develop a hypersensitivity to flea saliva, setting off a big reaction in the skin.

What are the signs of flea allergy dermatitis?

Clinical signs of dermatitis in cats can be from any number of sources, however in flea allergic dermatitis owners will see:

• Intense itching (pruritus)
• Fur loss (alopecia)
• Facial dermatitis (skin lesions around the face area)
• Miliary dermatitis (small papules which become crusted)

It must be remembered that other causes must be ruled out, as dermatitis in cats can be caused also by:

• Food allergy
• Mite infestation (mange, cheyletiella etc)
• Atopic dermatitis (a type of eczema)
• Dermatophytosis (ringworm)
• Drug hypersensitivity
• Bacterial infections
• Idiopathic dermatitis (skin inflammation with no known cause)

How is flea allergy dermatitis diagnosed?

The diagnosis of FAD needs to take into account the following factors:

• Clinical history - has the cat had this condition before? Are there any changes in the environment? What is the cat fed? What flea treatments to use on your cat? Do you treat the home with flea insecticides? These are the kind of questions that need to be answered as honestly as possible, for the veterinary surgeon to make an accurate diagnosis. It is not worth feeling that everyone will think your home is dirty, as a cat with hypersensitivity only needs one flea bite to set them off.
• Presence of fleas or flea dirt on the cat - the veterinary surgeon will visually check for fleas on the cat, or flea dirt (excrement). If the cat is very sensitive there may be no evidence of live fleas on the cat, especially as most will self-groom excessively. In this situation the vet or nurse may use a fine tooth comb to examine the coat. If flea dirt is suspected, it can be detected by the use of a damp paper test, where the dirt is crushed onto the paper. If the paper produces a reddish brown colour then there is evidence of flea dirt. (Flea dirt itself is dried blood).
• Allergy testing - in extreme cases the owner may be offered allergy testing of the cat to see if they are allergic to flea saliva. This process can be very expensive and does not always indicate the condition is flea allergy dermatitis; a positive result will still need to take into account all the factors above to reach diagnosis.

How is flea allergy dermatitis treated?

The biggest and most important treatment for flea allergy dermatitis is the control of fleas. Only by eradicating the flea population around the animal can the dermatitis be fully treated. This is often easier said than done, as most cats spend much of their time outdoors where they may be prone to be bitten by fleas. To have the best chance of controlling fleas the cat owner will have to take a four pronged approach:

• Flea treatment of the cat - eliminating fleas on the cat can be achieved by using safe and effective flea insecticide preparations. These can be spot-on flea applications, sprays or oral treatments. There are numerous preparations available and owner must be aware that just one application will not be enough. F cat that has suffered flea allergy dermatitis will need regular strict treatment for flea infestation.
• Treatment of all other animals - if there are other animals, especially dogs, in the home then they must also be treated regularly, even if they show no signs of flea activity.
• Treatment of the environment - fleas in the developmental and immature stages can be found in the environment. For one adult flea found on the cat, another 9 will be in the home. Flea eggs, larva and pupa can develop in any normal household. By using an insecticidal spray, not just on soft furnishings and carpets but on hard, wooden and laminate flooring as well (eggs can find their way into any tiny crevice), flea development can be stopped. Since immature fleas move away from light, skirtings and along the edges of rooms must also be paid attention to.
• Cleaning of bedding - regular vacuuming and hot washing of pet bedcovers, cushions and anywhere where the cat lies or sleeps will help reduce the environmental flea burden. Some owners even choose to place a flea collar inside their vacuum cleaner!

To support the cat, various medications can be given by the veterinary surgeon to bring the disease under control and to help heal the cat's skin.

• Steroid therapy - steroid use in cats can help control inflammation and calming the itch/scratch cycle. This is only a temporary measure while flea control is achieved and due to side effects long-term therapy with steroids should be avoided.
• Antibiotics - antibiotics are commonly used to control secondary bacterial infections often caused by flea allergy dermatitis.

Owners of affected cats must be made aware that recurrence of flea infestation and flea allergy dermatitis are common, once therapy has been stopped. Only vigilance and proper flea control on their part can help prevent future FAD occurrences from happening.