Flea allergy dermatitis: Is your dog or cat allergic to fleas?
As if flea bites were not itchy enough, some dogs and cats might also be allergic to fleas, causing them intense irritation.
You may not have heard of it but flea allergy dermatitis (FAD) is one of the most common skin diseases in animals1. Scratch your curiosity itch to discover more about this condition and if your cat or dog is allergic to fleas.
What is flea allergy dermatitis?
Flea allergy dermatitis, or FAD, is a skin allergy to a flea bite, which affects cats and dogs. However, it is not the flea they are allergic to; in fact, it is a reaction to certain proteins in the flea’s saliva that causes intense irritation to your pet’s skin.
Dogs and cats come into contact with the saliva allergen when fleas bite and feed on them. Just a single bite can lead to severe skin discomfort, making it even more important to help keep your pet free from fleas.
Which pets are particularly at risk of Flea Allergy Dermatitis?
Any adult dog or cat of any breed can have FAD.
Dogs tend to develop clinical signs of FAD between the ages of one and three years and it’s much less common in dogs under six months. Once diagnosed with FAD, dogs have it for life.
FAD is prevalent when fleas are around. The warmer summer weather was once an indicator that ‘flea season’ had arrived. Now, due to modern houses with central heating and milder winters, a flea infestation can occur throughout the year, putting pets with FAD at risk unless an appropriate preventative treatment is given.
Signs of flea allergy dermatitis
It’s difficult not to notice if your dog or cat has FAD. This allergy doesn’t cause the normal everyday itch; instead, your pet will be scratching as though their life depended on it.
A never-ending itch is the most common sign of FAD but, if you’re unsure, signs also include:
- Excessive grooming – your dog or cat grooming more than normal, chewing and licking their skin and scratching themselves on objects. Cats with FAD may not appear to be itchy as they tend to show increased grooming behaviour rather than scratching.
- Restless behaviour – your pet is unable to relax, appearing uncomfortable.
- Visible fleas – a flea on your pet, or flea faeces, known as flea dirt, which appears as black spots on the skin of the animal and turns into a rust-coloured substance when wet.
- Unusual odour – you notice a smell from their skin, which could be a result of a secondary skin infection.
- Changes in skin texture – areas of your pet’s skin feel different from normal. In some cases, your pet may display a type of skin lesion called miliary dermatitis, which are skin spots that feel similar to millet seeds - this is typically seen in cats with FAD.
- ‘Hotspots’ – in both dogs and cats, you should also look out for red and moist areas of skin called ‘hotspots’, which indicate a secondary bacterial or fungal infection due to extreme scratching. Unfortunately, the itchy feeling at these spots will be even more intense than first signs of FAD.
Although FAD is the same condition in both dogs and cats, it can appear differently on their skin:
DogsDogs tend to lose hair in patches, while the skin will be red and can appear thicker than normal due to excessive scratching. Signs are usually at the lower back area, the base of the tail, thighs and belly.
CatsCats usually display hair loss as a result of excessive licking. You might notice thinner hair at the tail base, on the belly, and hind legs. There may also be small scabs in these areas and around the back of the neck.
How is FAD diagnosed?
If your dog or cat is scratching or grooming themselves excessively, it’s a good idea to visit the vet. You may not have noticed any fleas on your pet but that doesn’t mean they’re not there. Although in some cases, pets with FAD often groom themselves so much they actually remove fleas and flea dirt from their coat. Even so, the allergic reaction can hang around for weeks. Plus, without a preventative treatment, there is a possibility of re-infestation.
Excessive scratching may also be a result of another health problem, so it’s important to visit the vet to get the right diagnosis and treatment.
Your vet will determine whether your pet has FAD by initially looking for fleas in their fur and on their skin. But, as pets will often remove them through grooming, the vet may need to carry out skin tests to rule out other causes.
Flea treatment is often prescribed for any pet with an itchy issue because fleas can exacerbate any skin problem, not just FAD. A positive response to flea treatment can also help to confirm diagnosis of fleas in a pet with FAD.
Treatment for Flea Allergy Dermatitis
If your pet is diagnosed with FAD, always follow your vets advice, this may include some of the following steps to help get your pet back to their usual healthy happy selves.
Step 1: Treat your dog or cat against fleas
Treatment against fleas is essential to bringing an end to your pet’s misery. An effective flea control product will help to reduce your dog or cat’s exposure to flea saliva.
There are many different flea treatments available:
Flea collars can vary in how they work; Seresto Flea and Tick Control collar kills fleas (and repels and kills ticks) through contact without the need for them to bite your pet2. Just put it on your pet like a normal collar and with Seresto they’re protected for 7-8 months.
Spot-on treatments, such as Advantage Spot-on, contain a small amount of liquid that is applied to the skin at the base of the cat's head or between the dog's shoulders once a month. Many pet owners find them convenient as they are easy to apply. Advantage Spot-on kills fleas within 24 hours and and prevents further infestations for 4 weeks. Fleas are killed through contact with the treated pet and do not have to bite to die2.
Tablets are another commonly used method to protect dogs and cats from fleas and can be given either by putting the tablet in with your pet's food or treats, or by gently giving it directly into their mouth. An example of a tablet available for preventative flea control is Advantage Chewable Tablets. This a tasty, meat-flavoured chewable tablet for dogs that provides fast-acting, reliable protection, killing fleas in just 4 hours and ticks in 8 hours3. Speak with your vet about preventative flea control for cats. If your pet already has an infestation of fleas, one Capstar tablet starts killing adult fleas in just 15-30 minutes and lasts 24 hours; to prevent a re-infestation of fleas, you'll need to use a longer-acting preventative product afterwards too.
Remember, your pet will only be fully protected from fleas when regularly using a preventative flea product. It can help to make a note of the date that you first gave the product, so you know when to re-treat. When applying flea treatments, you will need to choose the right product for your pet’s age and weight; always make sure you read the label and consult your vet or local pet retail store if you’re unsure.
Responsible use of medicines in pets
When we use pet health treatments, be they for parasites or for other health issues, it's essential that they are used responsibly. Find out more about the principles of responsible use of medicines in pets.
Flea treatment options
Step 2: Soothe the itch
Once flea treatment has been given, your vet will then relieve the desperate itch.
If your pet has picked up a secondary infection as a result of scratching and biting their skin to relieve their allergy symptoms, the itching will have become even more intense. To tackle this, your vet may prescribe antibiotics.
Your vet may also recommend medication to directly ease and soothe your pet’s inflamed skin.
Step 3: Treat your home against fleas
To help prevent reinfestation, you will need to ensure your home is free from fleas, as well as your pet.
When your pet has fleas, the adult fleas feeding on them make up a small fraction of the infestation, as there will be flea eggs and immature life stages hidden in carpets, soft furnishings and cracks in the floorboards throughout your house.
You can remove fleas from your home with these steps:
- Regularly clean your bedding and your pet’s bedding on a hot wash
- Vacuum your house frequently, paying particular attention to your pet’s favourite areas and under furniture
- Vacuum or clean cushion covers on your couch
- Regularly empty your vacuum cleaner and, for bagless vacuums, clean the cylinder where the dust collects to fully remove fleas from your home
- Finally, you may want to use an additional household flea treatment to prevent the development of any flea eggs and larvae you have missed, or are hiding in hard-to-reach areas. Speak to your vet or local pet retail store for more information about the use of these products.
Step 4: Avoid irritating pet flea sprays and shampoos
If you are thinking of using a topical flea treatment to rid your dog or cat of fleas, speak to your vet first. When skin is already inflamed, shampoos and sprays designed to repel or kill fleas contain chemicals that could easily irritate skin further. Even ‘natural’ remedies such as essential oils can make the situation worse.
Step 5: Attend check-ups after treatment
When your pet has suffered an infection, (as advised by your vet) it is important to attend the check-up appointment following treatment to ensure the antibiotics are working and the infection has cleared.
Want to know more?
- Small animal dermatology, 4th edition, 2017.
- Mehlhorn et al. Parasitol Res (2001) 87:198-207, information is regarding mode of action and is not intended to relate to speed of kill or to imply parasites can be completely stopped from biting.
- Advantage Chewable Summary of Product Characteristics.
