Cat vs Dog. Can Fleas Jump Between Species?


Fleas are a common external parasite that can infest both cats and dogs. According to studies, flea infestation rates can be quite high in pets, with one survey finding 28.1% of cats and 14.4% of dogs infested [1]. Fleas are able to jump from one host to another, allowing them to spread between cats and dogs living in the same home. If left untreated, flea infestations can cause skin irritation, infections, and anemia in pets. It’s important for pet owners to understand how fleas transfer between cats and dogs and to take preventative measures.

Flea Biology

Adult fleas feed on blood from cats, dogs, and other mammals. The adult female flea can lay up to 50 eggs per day, which fall off the animal host into carpets, bedding, grass, or soil (CDC). The eggs hatch into larvae within 2-12 days, depending on environmental conditions. The larvae feed on organic debris and mature into pupae, remaining in the pupal cocoon for 1-2 weeks before emerging as adult fleas (PetMD).

Importantly, flea eggs and larvae develop in the environment, not on the animal host. However, adult fleas can jump from one host to another when taking a blood meal, allowing them to spread between cats, dogs, and other animals in close contact (CDC).

Flea Transmission

Fleas spread primarily by jumping from one host to another. Their legs are designed for jumping long distances, allowing them to easily move between household pets and other animals.

Close contact between pets allows for easy spread of fleas within a home. Dogs and cats that sleep together, play together, or groom each other are likely to pass fleas back and forth. Fleas can jump from one pet to another any time the animals are near each other.

Fleas do not remain on a host animal when it dies, as they require live hosts for their survival. When an infested pet passes away, the fleas will rapidly seek out new hosts to provide them with blood meals. This is why flea infestations can seem to appear suddenly after the death of a pet.

While fleas prefer to live on furry or feathered animals, they can sometimes bite people as well. But they do not establish long-term infestations on human hosts. Their bites are uncomfortable for humans, but fleas cannot reproduce without an animal host.


Preventing Flea Transmission

Treating all pets in the household is crucial to preventing reinfestation of fleas. Fleas can easily spread from one pet to another, so leaving even just one untreated pet can allow the infestation to persist. Using flea collars, topicals, pills, or other prevention products on every cat, dog, and other furry pets in the home is recommended.

In addition to treating pets, it’s important to treat the home environment. Flea eggs and larvae can survive for weeks or months in carpets, bedding, and other fabrics. Frequent vacuuming and washing of pet bedding is advised. Vacuum all floors, furniture, and pet areas thoroughly to remove any signs of fleas or flea dirt. Wash all pet bedding in hot, soapy water as well. For a more thorough treatment, consider contacting a professional exterminator to treat the home and yard.

Treating both pets and premises is key to breaking the flea life cycle and preventing reinfestation. With diligent prevention and treatment, flea transmission between household pets can be avoided.

Treating a Flea Infestation

The first steps in treating a flea infestation are giving your pet a flea bath and thoroughly combing their coat to remove all fleas, eggs, and debris. According to veterinarians, bathing your pet in warm water can help kill and wash away fleas (Source). Be sure to use a flea shampoo and lather your pet well, especially around the neck, base of the tail, and other areas where fleas congregate.

It’s also important to use a fine-toothed flea comb to meticulously comb through your pet’s entire coat. Dipping the comb in a mixture of water and dish soap can help remove fleas and eggs (Source). Be sure to dip and rinse the comb frequently to dispose of any fleas you catch.

In addition to bathing and combing, your veterinarian can recommend safe, effective flea medication to kill adult fleas and prevent reinfestation. It’s crucial to follow your vet’s dosage instructions carefully and continue treating your pet until no live fleas are seen for at least a month.

Keep in mind that flea eggs can survive in carpets and bedding for weeks to months. Be patient and persistent, as it may take some time for all flea eggs in the home environment to hatch and be eliminated. Treating your pet and home thoroughly is key to getting rid of a flea infestation.

Flea Allergy Dermatitis

Some pets have an allergy to flea saliva that can cause a condition called flea allergy dermatitis (FAD) (1). When a flea bites a dog or cat with FAD, the saliva triggers an allergic response that leads to intense itching, hair loss, and skin infections (2). The itching is often focused around the base of the tail, thighs, abdomen, and neck but can be generalized in severe cases (3).

If you suspect your pet has FAD, it’s important to get veterinary help for proper diagnosis and treatment (2). Treatment focuses on preventing fleas to control the allergy signs. Your vet may recommend flea prevention products, anti-itch medications, antibiotics for secondary skin infections, medicated shampoos, immunosuppressive therapy, or immunotherapy (3). Keeping your home and yard flea-free is also critical for managing FAD (1).



Flea infestations can lead to severe anemia, especially in vulnerable animals. Young, old, or weak animals may be unable to withstand the blood loss from frequent flea feeding and develop anemia as a result (Source).

A single flea can ingest up to 15 times its body weight in blood daily. With a heavy infestation, this can amount to a significant blood loss for the pet. The ensuing anemia occurs because the fleas ingest more blood than the pet’s body can replenish (Source).

Signs of flea-induced anemia include pale gums, lethargy, weakness, collapse, and rapid breathing or panting. These symptoms indicate a dangerous depletion of red blood cells that requires prompt veterinary attention and treatment.

Severe flea anemia can be fatal if left untreated. At the first signs of anemia, pets should be brought to a veterinarian for blood tests, iron supplements, fluids, and medications. Getting the flea infestation under control is also essential for allowing the pet to recover from the anemia.


Fleas can transmit tapeworm eggs to pets when swallowed during grooming, particularly flea larva that contain tapeworm cysts. According to the CDC, “A dog or cat may swallow a flea while self-grooming. Once the flea is digested by the dog or cat, the larval tapeworm is able to develop into an adult tapeworm.”[1] Once inside the pet’s digestive tract, the tapeworm causes issues like digestive upset and pets may show signs such as vomiting or diarrhea. Owners may also notice tapeworm segments in their pet’s stool or around their hindquarters.

If a pet has a flea infestation and shows signs of tapeworms, they likely need to be dewormed. According to VCA Animal Hospitals, “You cannot get Dipylidium caninum tapeworms directly from your dog, as it depends on the flea as the intermediate host.”[2] So treating both the tapeworm infection and flea infestation is key. Pet owners should bring a fresh fecal sample to the vet so the right dewormer medication can be prescribed.

When to See the Vet

If you notice signs of a severe flea infestation or complications from flea bites, it’s important to see your veterinarian. Some reasons to make an appointment include:

  • Flea treatments don’t seem to be working. Your vet can recommend alternative products or treatment methods.
  • For signs of infection, allergies, or anemia. Flea bites can lead to secondary skin infections. Pets with flea allergy dermatitis may require medications. Severe infestations can cause anemia from blood loss.
  • To diagnose and treat tapeworms. Tapeworms are transmitted by ingesting fleas. Your vet can provide tapeworm medication.
  • For skin issues related to flea allergy dermatitis. Anti-itch shampoos, oral antihistamines, steroids, or immunotherapy may be recommended.
  • If your pet seems very weak or lethargic. This could signal anemia from flea bites and may require a blood transfusion.

See your vet promptly if you notice any of these signs. They can help diagnose the underlying issue and get your pet appropriate treatment.


Fleas readily spread between cats, dogs, and other hosts. These pests can travel easily between close contacts, and just a few fleas can lead to a large infestation. Prevent fleas and treat all pets in a household to control infestations. Use a combination of oral/topical medications, thorough home cleaning, and environmental control like sprays or foggers. Monitor closely to ensure fleas don’t persist after treatment. Seek veterinary care if fleas cause health issues like anemia, allergies, or tapeworms, or if they don’t respond to diligent treatment efforts. Staying on top of flea prevention and control can help pets stay happy, healthy, and itch-free.

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