Facts about fleas

Flea Factsby Robert B. Duncan, DVM
Spring Branch Veterinary Hospital


How do pets get fleas?

Cats and dogs are two of the preferred hosts for fleas. The cat flea (Ctenocephalides felis) is by far the most common flea found on cats and dogs. When a flea finds an unprotected dog or cat, it will bite and feed on the pet’s blood. The next step is reproduction. Like the life cycle of a butterfly, flea development involves an egg, larva, pupa (cocoon) and adult. The flea eggs are laid in the pet’s hair coat but fall off and hatch in the environment. A female flea will start laying eggs 20 -24 hours after its first blood meal off the pet. A female flea can lay as many as 50 eggs per day! Also keep in mind that the adult fleas on a pet with an infestation represent only 5% of the fleas involved. 95% of the related fleas are in the egg, larva, and pupa form wherever the pet likes to rest.

How do I know if my pet has fleas?

Red flags for fleas on your pet include biting or scratching at skin, hair loss (often times over rump area), and the presence of ”flea dirt” (flea feces) in the pet’s hair coat and/ or bedding. “Flea dirt” often appears similar to coffee grounds having been sprinkled. An absence of regular flea prevention along with the symptoms mentioned above is usually enough to suspect flea involvement.

What problems can fleas cause?

Flea allergy dermatitis is the most common skin disorder or dogs in the United States. Not only do fleas produce skin irritation and allergic dermatitis in pets, but they also transmit tapeworms (Dipylidium caninum) to dogs and cats. For puppies, kittens, and smaller adult pets, fleas can be a life-threatening cause of anemia (red blood cell deficiency). Flea feces will often times contain the bacterium Bartonella hensalae which is responsible for cat scratch disease in people.

How can fleas be controlled?

All pets in the household need to be on a monthly flea preventative recommended by a veterinarian. The all-inclusive parasite preventatives used most commonly at SBVH (Trifexis and Advantage Mulit) include a flea adulticide which kills adults before they have a chance to reproduce, thus breaking the flea life cycle.

What if I’m still seeing fleas on my pet even with a monthly preventative?

Fleas still have to get on the pet in order for the products to work. So if fleas are still seen on pets that are current on a monthly preventative, most likely there is a high flea burden in the environment. This means they are either inside or outside or both. A high flea burden can still be seen indoors if all pets in household are not on a preventative or if the pet(s) were only recently placed on prevention after having a flea infestation. As mentioned above, 95% of fleas involved with a pet infestation will be I the pets bedding, the carpet, or wherever the pet likes to be. These pre-adult fleas will develop into adults between 3-6 weeks in typical household conditions. This means that new fleas will be emerging in the house for up to 6 weeks after a pet infestation! In this case, it is best to have the home treated by a professional exterminator or have the home steam cleaned. If it is suspected that the fleas are coming from the yard, outdoor treatments may be necessary.