Do Cat Fleas Also Plague Our Pups? The Truth About Cross-Infestation

Fleas are a common problem for pet owners. These tiny parasites can cause major irritation and health issues for dogs. Cat fleas are especially prevalent, even on dogs. If you’ve noticed your dog scratching more than usual, fleas may be the culprit. But where do these pests come from?

Life Cycle of Fleas

Fleas go through four distinct life cycle stages: egg, larva, pupa, and adult. Adult female fleas live on the skin and fur of dogs, cats and other animals and lay eggs. According to the University of Florida Entomology Department, adult female fleas will lay around 30-50 eggs per day[1]. These eggs fall off the animal and onto the floor, furniture, pet bedding and anywhere the pet goes. The eggs hatch into larvae within 2-12 days.

The larval stage is the longest stage, lasting 5-11 days on average. Larvae feed on organic debris and adult flea feces, which contains dried blood. Larvae dislike light and move deep into carpets, furniture or bedding material away from light. After the larval stage, the mature larva spins a cocoon around itself and enters the pupal stage. This is the transition stage from larva to adult. The pupal stage typically lasts 5-10 days before the adult flea emerges from the cocoon ready to find a host and begin the cycle again. Newly emerged adult fleas are very active and immediately seek a host for a blood meal.

The entire flea life cycle can be completed in as little as 2-3 weeks. This allows populations to grow rapidly, especially in warm, humid environments. Breaking the flea life cycle involves treating both the pet and the home environment.

Can Cat Fleas Live on Dogs?

Yes, cat fleas can and do live on dogs. Despite their name, the fleas known as cat fleas (Ctenocephalides felis) are capable of infesting dogs as well as cats (1). In fact, cat fleas are the most common species of flea found on dogs and cats in North America (2).

Cat fleas do not discriminate between dog and cat hosts. They feed on the blood of cats, dogs, and other animals indiscriminately (1). The presence of a particular host animal simply provides them an opportunity for food. So if cat fleas come into contact with a dog, they are perfectly happy to take up residence and start feeding there.

Cat fleas are well-adapted for life on dogs. Their flattened bodies allow them to move deep into a dog’s coat and remain close to the skin for feeding (3). They can survive for weeks on a dog host. Therefore, dogs living closely with flea-infested cats are very likely to pick up cat flea infestations themselves.

In summary, cat fleas do not exclusively live on cats. Dogs make perfectly suitable alternate hosts for cat fleas to thrive on. So cat flea infestations can spread rapidly between cats and dogs living in close proximity.



Do Cat Fleas Lay Eggs on Dogs?

Yes, female cat fleas do lay eggs on both dogs and cats. Cat fleas (Ctenocephalides felis) are parasites that live on the blood of their hosts and rapidly reproduce. According to, female fleas prefer laying eggs on areas with shorter hair and closer to the skin, such as around the neck on cats and near the hips on dogs [1].

After feeding on blood, the female cat flea can lay up to 50 eggs per day and around 2,000 eggs over her lifetime. These small white oval eggs easily fall off into bedding and carpets as the host animal moves around [2]. The eggs hatch into larvae in just 2-14 days, beginning the flea life cycle all over again.

So in summary, yes, female cat fleas readily deposit eggs on dogs, just as they do on cats. This allows their population to rapidly multiply. Checking your dog’s skin and bedding for signs of flea eggs can help you identify an infestation early.

Signs of Flea Infestation

There are a few key signs to look out for to determine if your dog has a flea infestation:

Itching and Scratching – One of the most common signs of fleas is excessive itching and scratching from your dog. The fleas bite and feed on your dog’s blood, causing irritation and itchiness. You may see your dog scratching, chewing and biting at his skin constantly.

Skin Irritation and Redness – The flea bites can cause red bumps, rashes and inflammation on your dog’s skin. This can lead to skin irritation, infections and hot spots from constant biting and scratching [1].

“Flea Dirt” – Flea dirt appears as tiny dark specks, similar to ground pepper. It is actually flea excrement that contains digested blood. You may see flea dirt in your dog’s coat or on his skin, especially around the belly, tail and hind legs.

Seeing Fleas – Carefully look through your dog’s fur and comb him with a fine-toothed flea comb. You may see live fleas scurrying around his coat. Fleas are brownish-red insects that are only about 1-4 mm long.

Effects of Fleas on Dogs

Fleas can cause a variety of health issues in dogs beyond just itchy irritation from bites. Some of the most common flea-related conditions include:

Flea Allergy Dermatitis

Flea allergy dermatitis (FAD) is one of the most common skin conditions in dogs. Dogs with FAD are allergic to flea saliva, and just a few flea bites can trigger intense itching, scratching, hot spots, and hair loss. FAD can result in significant skin damage and secondary skin infections if not treated properly (


Young, old, or sick dogs with heavy flea infestations can develop flea bite anemia. Fleas feed on blood, and a high number of fleas can cause blood loss leading to anemia. Signs include lethargy, pale gums, and rapid heart rate (


Tapeworms are transmitted by fleas. Flea larvae ingest tapeworm eggs, which develop into adult tapeworms inside the flea. When the dog swallows an infected flea while grooming, the tapeworm is transmitted. Tapeworm segments resembling rice grains may be visible in the dog’s feces or around the anus (

Treating Fleas in Dogs

Treating a flea infestation requires attacking all stages of the flea life cycle. There are several effective treatment options to kill adult fleas and prevent future infestations.

Topical Treatments: Topical flea prevention products like Frontline Plus ( and Advantix are applied to the skin and distribute medication across the body. They kill adult fleas and prevent eggs from hatching.

Oral Treatments: Oral flea medications like Nexgard or Simparica contain insecticides that spread through the bloodstream when absorbed. They begin working within hours to kill fleas and break the life cycle (

Flea Collars: Flea collars like Seresto release small amounts of insecticide that spread across the fur. They provide continuous protection for months.

Cleaning: Thoroughly clean your home and wash all bedding to remove eggs and larvae. Vacuum regularly and dispose of the bag to prevent reinfestation.

Treating both your dog and home environment is key to getting rid of fleas. Consult your vet to determine the best treatment plan.

Preventing Fleas in Dogs

There are several effective ways to help prevent fleas in dogs. Some key prevention methods include:

Treatments – Giving your dog regular flea and tick prevention medication is crucial. Products like Nexgard, Advantix, Frontline, and Seresto collars can kill and repel fleas for up to a month with each application.

Cleaning – Vacuuming floors, furniture, and pet beds frequently can help remove flea eggs and larvae. Also wash your dog’s bedding regularly in hot, soapy water. Be sure to empty the vacuum after each use.

Keeping grass short – Fleas thrive in tall grass and shrubbery. Keep your lawn mowed short and trim back overgrown areas in your yard. This will help reduce flea populations outside.

Check for fleas – Examine your dog’s coat thoroughly each week and look for signs of fleas like black specks (flea dirt). Catching an infestation early makes treatment easier.

With diligent prevention and prompt treatment if fleas are found, you can help keep your dog flea-free and comfortable.

When to See a Vet

In most cases, you can treat a flea infestation at home with topical and oral medications, frequent bathing, and thorough cleaning of your home. However, it’s important to see your veterinarian if the infestation persists despite your best efforts.

Signs that warrant a veterinary visit include:

  • Fleas remain after treating your dog and home multiple times
  • Your dog is excessively scratching, biting, or licking themselves
  • You notice skin irritation, hair loss, scabs, or hot spots on your dog
  • Your dog develops skin infections from excessive biting and scratching

Veterinarians have access to prescription-strength flea treatments that are more effective than over-the-counter options. They can also diagnose and treat any secondary skin infections caused by flea bites (1). Your vet may recommend shampoos, antibiotics, or anti-inflammatory medications to soothe your dog’s irritated skin and treat infections.

Don’t delay in seeking veterinary care if your dog has signs of persistent flea infestation or skin infections. The sooner the underlying cause is addressed, the quicker your dog will feel relief and recover.


In summary, while cat fleas and dog fleas are different species, cat fleas can and do live on dogs. Cat fleas will readily feed on dogs, lay eggs in the dog’s coat, and complete their entire life cycle on canine hosts. Therefore, dogs living in close proximity to cats may become infested with cat fleas. The signs of flea infestation in dogs include excessive scratching and licking, flea dirt in the coat, skin irritation, and hair loss. Flea infestations can cause significant irritation, discomfort, and even anemia in dogs. Preventing fleas through monthly treatments and diligent housekeeping is key. If a dog develops a flea infestation, speak to your veterinarian about safe and effective treatment options to kill adult fleas and their eggs. With proper prevention and prompt treatment, dog owners can protect their beloved pets from the nuisance of cat fleas.

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