Finding and removing fleas on dogs

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As a dog owner, few things can be quite as frustrating as fleas on your dog. One of the most common causes of skin conditions and itching in dogs, fleas can give painful bites, cause allergic reactions and, in some cases, transmit disease. Some people also worry that fleas somehow mean their house or their dog is dirty. Rest assured, however, that this is not the case; fleas are very common and every dog will get them from time to time, simply from going for walks and going out in the garden. While an infestation is irritating, it is manageable. With just a little work, fleas can be treated and prevented. Read on to learn how.

What are fleas?

The first step in dealing with fleas is to understand them. Fleas are small, flightless insects that feed on blood. They should be visible to the naked eye, but if your dog has dark fur, you may have an easier time seeing them against the skin. Otherwise, you have to hunt for them.

Fun fact: the vast majority of flea infestations in dogs are actually a species of cat flea that’s hopped on for a taste of something different. They can survive on dogs and other pets, but cats are still more likely to be their main form of food/transport.

Lifecycle of a flea

A flea goes through four stages in its lifetime: egg, larvae, pupae and adult. Adult females lay eggs in batches of around 20. Eggs are very small, oval-shaped, and grey or white in colour.

Eggs are laid on the host but are usually quick to fall to the ground. Eggs can fall off your dog when they shake, scratch, or simply walk around the house. They can then hide in carpets, soft furnishings, and even cracks or gaps in hard floors. 

Bear in mind that once dropped, flea eggs can survive for weeks and even months without a host, just waiting for the right conditions to hatch. During this time, they can be carried around the house by slippers, paws, and other things. This is why the spring season following an infestation is often a peak time for flea activity in your home, as the rising temperature helps surviving flea eggs to develop and hatch. These days, with central heating, fleas can also be a problem all year round.

Once flea eggs hatch, larvae emerge, feeding mostly on debris such as faeces, dead insects, or vegetable matter. Within a week or two, the larvae will spin cocoons and “pupate” for another one to two weeks. Adult fleas will then emerge and must immediately find a host for a source of blood.

Fleas tend to specialise in a particular kind of host. The type you'll find on your dog won't normally feed on humans, but there are always exceptions.


It is much better to prevent a flea infestation in the first place, rather than try to eliminate one later. There are plenty of preventative treatments available nowadays, such as spot-ons that you can apply at various intervals throughout the year, depending on the product.

Spotting the signs of a flea infestation

The most common signs of fleas on your dog are itching and scratching, especially around the neck and the base of the tail. You may also notice hair loss and crusts on the skin. 

Fleas don’t spend much time on the animal, so they can be difficult to spot unless there are lots of them. But for every one you see on your dog, there are 100 in the house! A great way to detect fleas is to look for flea poo. Comb your dog onto a piece of white paper towel and moisten what comes out. If it stays dirt-coloured, it’s dirt. If it goes red, it’s flea poo full of blood!

Flea treatment

Your vet can recommend a number of treatments to help quickly eliminate fleas and their eggs. These usually work by killing adult fleas or by weakening larvae.

Because treatment usually only affects fleas in one of their life stages, it’s important to supplement any treatment with diligent cleaning of your dog's bedding and any furniture or blankets they like to lie on. 

Be wary of flea treatment products not provided or recommended by your vet, as it can be harder to ensure their effectiveness and safety. As ever, it’s always wise to consult with your vet before beginning any sort of treatment on your dog. Only ever treat your dog with a flea treatment intended for dogs, and do not treat cats, rabbits, or other pet species with your dog’s flea treatment. Using a flea treatment intended for another species can be deadly.

You should treat the house, too. Ask your vet for a treatment recommendation, as it’s important to make sure the product is safe for other pets and family members in the home, too. Careful vacuuming with particular attention paid to nooks, crannies, and upholstered furniture will go a long way towards getting rid of eggs, larvae, and cocoons. When you treat the house, the vibrations of the vacuum cleaner will stimulate the eggs to hatch and the treatment will be more effective.

Reviewed by Dr. Hein Meyer, DVM, PhD, Dipl-ECVIM-CA and Dr. Emma Milne BVSc FRCVS