Shoo, Flea: What to Do About Your Dog’s Disturbing Flea Allergy · The Wildest

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Shoo, Flea: What to Do About Your Dog’s Flea Allergy

Before you say “ew David” Moira Rose-style, learn these steps to prevent and remove fleas

by Sara Greenslit, DVM
31 October 2023
Black puppy itches behind her ear due to flea allergy
Christian Müller / Adobe Stock

When humans start to scratch our scalps more than usual, we get worried. Many of us have traumatic lice stories from primary school that would rightfully elicit a disgusted “ewww” from Moira Rose. She would, no doubt, have the same reaction to a dog scratching ceaselessly because of – the horror – fleas.

If your dog has fleas, the first thing you may notice is hair loss along their neck, spine and thighs. Their skin may also be flecked with scabs and hot to the touch. Then, of course, there’s the scratching: automatic, back-foot-reaching, irrepressible itching. You may or may not see live fleas; it’s possible you’ll only see flea dirt (specks of digested blood).

Often, pet parents will think, ‘But my other dog (or cat) is just fine.’

That’s the thing: not all dogs are allergic to fleas. But for the ones who are, the suffering can be extreme. As anyone who’s gotten a mosquito bite (or lice) knows, itching causes a distinct, exasperating distress. The good news is that it’s actually pretty simple to prevent and treat fleas on dogs. Here’s how.

First of all, what is flea allergy in dogs?

Flea allergy dermatitis (FAD) arises when your dog’s immune system overreacts to flea saliva. The severity of the itching doesn’t necessarily correlate to the number of flea bites your dog has; sometimes, it only takes a few to generate a whole lot of scratching. Many dogs will also have secondary bacterial and yeast infections, as well as environmental allergies, all of which aggravate the itch.

Flea allergy symptoms

  • itchy skin causing excessive scratching

  • fur loss

  • thickened skin

  • redness

  • hot spots

  • restlessness

  • scabs or crusts

How do you prevent flea allergy dermatitis in dogs?

According to Dr William Oldenhoff, a veterinary dermatologist at LeadER Animal Specialty Hospital, there are several steps you need to take. The first is to use a flea preventative medication year-round, which takes a while to resolve the infestation because the flea life cycle ranges from one to two months, depending on environmental conditions. Plus, pupae can survive for up to a year before reaching adulthood.

Oral medications

Dr Oldenhoff has been recommending new oral flea and tick preventives like NexGard, Bravecto and Simparica – isoxazoline acaricides and insecticides for use with dogs only. He recommends these products because they are virtually foolproof. You don’t have worries like, Did I put the full vial on my dog? Did I get it right on the skin? Did I bathe my dog too quickly, thus washing it off? (Note that these are only available by prescription.)

Rigorous cleaning

Dr Oldenhoff also recommends cleaning your house thoroughly. “Vacuum all surfaces, paying particular attention to the areas adjacent to walls and corners and under furniture,” he says. “Be sure to clean the furniture as well and launder any bedding the dog sleeps on.” He does not recommend having the house itself sprayed or otherwise treated because flea preventives and meticulous environmental cleaning are usually enough to keep fleas at bay.

How do you treat flea allergy dermatitis in dogs?

The best treatment for flea allergy dermatitis in dogs is prevention. But, if your dog has fleas, after ensuring your house and your pup are clear of the pests, the next step is medical treatment. There are a couple of therapeutic options available to help soothe the irritation and relieve the secondary conditions caused by flea allergy dermatitis.

Itch treatment

A dog’s skin should be smooth and soft, but pups with flea allergy dermatitis often have red, irritated, itchy skin. To relieve the itch, some veterinarians prescribe Benadryl for dogs experiencing a mild allergic reaction. For more severe acute reactions, Dr Oldenhoff recommends oral meds such as oclacitinib or steroids.

However, he cautions, just because your dog stops their frantic scratching, it doesn’t mean the fleas are gone.

“When these therapies are prescribed, your dog will be feeling much more comfortable, but the flea infestation is still present, and thus flea prevention medication must still continue,” he notes. Other flea allergy dermatitis treatment options include antibiotic medications for secondary bacterial and yeast infections.

Allergy injections

Other integrative options include allergy injections. Because they’re based on your dog’s specific tested allergens, allergy injections may help with their concurrent atopy (the likely genetic tendency to develop allergic diseases) – but they will not directly affect flea allergy dermatitis.

Deworming treatment

A dewormer may be necessary if the dog has developed tapeworms due to fleas. Fleas harbour dipylidium caninum larvae (aka flea tapeworms). If an infected flea is ingested – for example, as the dog grooms himself – the larvae develop into adult tapeworms in the dog’s intestines. The good news is treatment for tapeworms is simple and effective. Your vet will most likely prescribe an oral medication called praziquantel.

Can fleas become resistant to flea products?

If flea control depends on flea products, and these have been used for many years, do fleas develop resistance? Hypothetically, they could. “In theory, resistance would be more likely with the products that have been on the market longer,” says Dr Oldenhoff.

A dog’s perceived resistance to flea products may also be the result of their exposure to feral cats and urban wildlife, or to other pets in the household (all of whom need to be treated year-round), in which case the infestation may continue.

Are there home remedies to treat flea allergy in dogs?

If you’re looking for a natural solution to a flea infestation, know that ‘natural’ does not necessarily mean ‘non-toxic’ or effective. Here are some common home remedies used to prevent fleas.

Diatomaceous earth and boric acid

Some people use diatomaceous earth or boric acid in their homes, particularly on carpet and around baseboards. These pesticides may kill some of the larvae to reduce the overall flea population, but it won’t be enough to gain full control of an infestation. The products can be harmful if applied directly on animals as well.

Both diatomaceous earth and boric acid have effects on humans and animals. Diatomaceous earth, a type of silica, can be an irritant to the eyes, skin and respiratory tract. Boric acid can be corrosive to the eyes and skin, cause vomiting and diarrhoea, respiratory difficulties, and (in large quantities) seizures and coma. You can take steps to reduce you and your dog’s exposure to these natural pesticides during their application, but in the end, basic house cleaning is your best tool against fleas.

Essential oil flea collars

You’ll also see flea collars made with essential oils. These collars are widely sold as unregistered repellents and not true insecticides, so manufacturers aren’t required to provide data regarding their usefulness. (Cats are especially sensitive to essential oils, so proceed with caution.)

Fish oil

Adding fish oil to a dog’s diet after initial treatments may help control flea allergy dermatitis by reducing inflammation. But applying oils – such as coconut oil – directly to the skin isn’t recommended. “I have seen animals with microbial overgrowth that I suspect was exacerbated by coconut oil application,” says Dr Oldenhoff.

A flea infestation can cause physical and emotional stress on everyone. No one wants fleas – not you and not your dogs. To keep your home flea-free, the best thing you can do is clean often. Pull out your vacuum – and if your dog runs away, tell them it’s for their own good!

sara greenslit

Sara Greenslit, DVM

Sara Greenslit, DVM, CVA, is a small-animal veterinarian and writer who lives and practices in Madison, Wisc.

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