Fleas in Dogs and Cats: Signs, Treatment and Prevention

Signs to watch for

Some pets with fleas scratch only now and then, while others are very uncomfortable. These are the most common signs.

• Scratching, biting or licking the skin, often at the base of the tail, the lower back, the belly and the back legs
• Restlessness and trouble settling down
• Small red bumps or scabs, which in cats often appear along the back and around the head and neck
• Thin or missing hair
• Black specks in the coat that look like ground pepper, known as flea dirt
• Small, rice-like segments near the tail or in the stool, which are pieces of tapeworm
• Pale gums and tiredness when there are many fleas

Cats groom thoroughly and often swallow the fleas they catch, so an owner may see scratching and scabs without ever spotting a flea.

Some dogs and cats are allergic to flea saliva, a condition called flea allergy dermatitis. In these animals, even a few bites can cause intense itching, hair loss, sore skin and skin infections.

A fine-toothed flea comb is the most reliable way to find fleas at home. Run it through the coat, especially along the back and near the tail, and tap what you collect onto a damp white paper towel. Flea dirt dissolves into reddish-brown smudges because it is made of dried blood. Ordinary dirt stays dark.

When it is an emergency

Most flea problems can wait for a regular vet appointment. A few situations need care the same day.

• A puppy or kitten with many fleas that has pale or white gums, seems weak or very tired, or stops eating. Heavy infestations can cause dangerous blood loss in young, small, old or weak animals.
• A cat that twitches, trembles, walks unsteadily or has a seizure after a flea product was used on it or on a dog it lives with.

Some flea products made for dogs, especially those containing permethrin, are very toxic to cats. A cat can be poisoned if a dog product is put on it by mistake or if it rubs against a recently treated dog. It is safest to use only products labeled for the species, age and weight of each animal and to ask your vet when unsure.

Why the home needs treatment too

Adult fleas stay on the animal and feed every day. Their eggs, larvae and cocoons live in the pet's surroundings, and in an infested home they usually far outnumber the adults. A female flea starts laying eggs within a day or two of her first blood meal and can lay 20 or more a day. The eggs drop off into bedding, carpets, sofas, car seats and shady outdoor spots where the pet rests.

The eggs hatch into tiny larvae that avoid light and hide deep in carpets and under furniture. They feed on skin flakes, other debris and flea droppings. When grown, each larva spins a cocoon. The young flea inside can wait for weeks or months until warmth, movement or the breath of a nearby animal makes it hatch and jump on. This is why a home left empty for a while can suddenly fill with hungry fleas when people or pets return.

The full cycle can take as little as two weeks in warm conditions and several months in cool ones. Fleas multiply outdoors from spring to autumn, and heated homes let them keep breeding through the winter. Pets usually pick up fleas where infested animals have been, such as gardens, parks, shelters and spots visited by strays, hedgehogs or other wildlife.

How vets diagnose and treat fleas

A vet usually confirms the problem by finding fleas or flea dirt during an exam. When a pet is very itchy but no fleas turn up, the vet may still suspect a flea allergy, especially in cats. The vet may also look for other causes of itching, such as mites or other allergies. If anemia is possible, the vet may check the gums and run a simple blood test.

Flea treatments come as spot-on liquids, tablets, chews, sprays and collars. Some kill adult fleas quickly. Others stop eggs and larvae from developing. Your vet can suggest a product based on the animal's species, age, weight, health and lifestyle, and how often to repeat it. Most products have a minimum age, so ask what is safe for a very young puppy or kitten.

Good flea control usually has three parts. The first is getting rid of the fleas on the pet. The second is treating every dog and cat in the home at the same time, even the ones that do not seem itchy, because an untreated animal keeps the cycle going. The third is cleaning the home. Regular vacuuming of floors, sofas and car seats removes many eggs and larvae, and so does washing pet bedding in hot water. In heavy infestations, your vet may also recommend a product for the home.

You may keep seeing new fleas for several weeks, because fleas waiting in cocoons keep hatching and jumping onto the pet. Getting a home fully clear often takes two to three months of steady treatment. Pets with flea allergy may also need medicine for the itch and for any skin infection, and the vet may suggest a tapeworm treatment as well.

Preventing fleas

There is no vaccine against fleas. Prevention means regular parasite control, planned with your vet for each animal. Many vets recommend keeping it up all year, since fleas can breed indoors in every season. This matters most in warm areas, in homes with several pets, and for dogs and cats that go outdoors or meet other animals.

Regular combing, especially in summer and autumn when flea numbers peak, catches a problem early. Treatments work best when given on time, since gaps let fleas return. Bathing or swimming can make some spot-on products work less well, so it is worth asking your vet how to plan baths around treatment.

Fleas, other pets and people

Fleas move easily between dogs, cats, rabbits, ferrets and other small mammals in the same home. If one pet has fleas, the others are probably exposed too, so ask your vet about treating them all. Some dog and cat flea products are dangerous for rabbits, so it is best to let the vet choose for each animal.

Cat and dog fleas prefer animals. They will bite people, though, especially when many fleas hatch in a home and no pet is around. The bites leave small, itchy red bumps. Fleas can also spread germs, such as the bacterium behind cat scratch disease, which can enter the skin when a scratch is contaminated with flea droppings. People can also catch the flea tapeworm by accidentally swallowing an infected flea. Both infections are more common in children. Keeping pets free of fleas, washing hands after handling animals and cleaning any scratch with soap and water all lower the risk. People with a weak immune system may want to ask their doctor.

Rescued and newly adopted animals

Street animals usually have no parasite control, so rescued dogs and cats often arrive with fleas, and sometimes with tapeworms or anemia. Puppies and kittens are the most vulnerable. European parasite guidelines count shelters, breeders and homes with several kinds of pets as high-risk places and advise steady, year-round flea control there.

The same guidelines note that parasites are very common around the Mediterranean, a region many rescued dogs and cats come from. In the Western Balkans, a survey of dogs seen at vet clinics in Serbia, North Macedonia, Montenegro and Bosnia and Herzegovina found that about four in five fleas were cat fleas.

At Paw Squadron, the first stops after every rescue are the vet and a bath. Each animal gets a checkup, deworming and treatment against fleas and other parasites. Before adoption, every animal also receives its vaccinations and a microchip.

Flea control needs to continue after adoption. It helps to ask the rescue team which product was used and when it was last given, so your own vet can plan the next treatment. If you already have pets, it is worth checking that their flea prevention is up to date before the newcomer arrives. In the first weeks, regular combing helps you catch any problem early, and washing the new pet's bedding often removes flea eggs. If you notice fleas, flea dirt, heavy scratching or tapeworm segments, call your vet.

If you are thinking about adopting, the Adoptions page shows the dogs and cats waiting for a home.