Clinical Signs, Infectious Diseases, and Natural Treatment Options for Fleas

Patrick Mahaney, VMD, CVA, CVJ
By Patrick Mahaney, VMD, CVA, CVJ on Jul. 3, 2012

Fleas are a subject of much disdain for people and pets alike. No pet owner wants to see their beloved Fido or Fluffy subjected to the blood sucking physiologic needs of the flea. Preventing flea infestation takes a consistent effort on behalf of the caretaker and requires attention to our pets, environment, and lifestyle choices.

Flea Appropriate Climate

Fleas require a climate sufficiently warm and humid to support their lifecycle. Yet, indoor climates can be sufficient year-round regardless of geographic location. Temperatures between 70-90 °F and humidity levels of 50-75 percent are needed for fleas to hatch and thrive on pets, wildlife, and in our shared environment.

Fleas lay eggs in clusters of approximately 20 at a time; one to two weeks are needed for eggs to hatch into larvae. Another one to two weeks are required for larvae to develop into pupae, and a final one to two weeks is needed for the adult flea emerge. So, only four to six weeks must pass for flea eggs to develop into adults.

Considering there are only 52 weeks in a year, this process is relatively quick. A single flea needs only to get onto your pet or into your home to start this process. You may not even know that this is happening unless your pet starts to clue you in on the annoying presence of fleas.

Clinical Signs of Flea Infestation

Fleas are opportunistic arthropods that seek out our pets as a food source. Yes, they need blood to survive. Once fleas get on your pet by jumping or crawling, they typically set up their habitat in hard to reach places, like the head, neck, tail, axilla (armpits), or inguinal area (groin). Licking, biting, or scratching at these places usually indicates the presence of nagging parasites.

Flea bite saliva is very allergenic (with some animals’ response being more pronounced than others), so flea allergy dermatitis (FAD, or skin inflammation due to flea bites and saliva) is not exclusive to the bitten body part. Additionally, the appearance of tapeworm proglottids (body parts) in a pet’s feces is another giveaway that a flea problem must be addressed.

A pet’s furry coat provides shelter for fleas, so our companion animals are often more affected by flea infestation than relatively hairless human bodies (plus, we bathe more frequently). The fur also helps to create the appropriate microclimate for flea eggs to develop into adults, and hides the flea excrement (AKA flea dirt).

Evidence of flea infestation can manifest as "ground black pepper-like" specks on your pet’s skin and coat. To differentiate flea dirt from day to day environmental debris, simply add water; moisten a white cloth and dab the area harboring the flea dirt. If the cloth becomes pink or red, then your suspicion of fleas has been confirmed.

Fleas Carry Disease

Fleas play host to a variety of infectious organisms, including bacteria, viruses, and parasites; Bartonella felis (the bacteria that causes cat scratch fever), Enterovirus (one of the causative agents of viral meningitis), Cestodes (tapeworm), and others.

These agents can be transmitted into dogs, cats, and other animals through multiple routes. When a flea feeds from its prey, the passage of blood allows for transfer of bacteria (and viruses). When irritated pets chew at themselves, they may consume the flea during their attempt to stop the nagging sensation.

Fleas act as an intermediate host for tapeworm, as adult fleas consume the tapeworm eggs. When the flea is consumed by the definitive host (your personal pet), the tapeworm then develops into an adult inside the host’s intestines. Tapeworm proglottids (body segments) appear like squirming grains of rice once the host’s feces exits the rectum. This is a big turn off for those of us who love rice with our sushi and creates the motivation to resolve and prevent infestations.

Naturally Rid Your Home of Fleas

Pet owners shouldn’t exclusively rely on topical and oral flea treatments to keep their dogs, cats, and households free of fleas (and ticks). Keeping the environment as flea-free as possible is my primary recommendation. Preventing your pet from going to heavy flea burden areas is my secondary recommendation.

Vacuuming your home has no direct toxic effects on your environment, home, or pet. Commit to performing a thorough vacuum job at least every seven days, including all rugs, upholstery, and even your car (if your pet accompanies you on vehicular excursions). Dispose of the canister or bag in a sealed container away from the house, as fleas and eggs may survive being sucked up into the vacuum and then emerge back into the environment.

Diatomaceous earth and boric acid can be sprinkled around your home and yard; both have a drying effect on flea eggs and adults. Use common sense when applying these agents, as both can create aerosolized debris that can be inhaled by pets and people. Keep your cats, dogs, and children out of the treated area until the dust has settled.

Adding garlic (fresh or powder) to your dog’s meals is another option (not for cats — garlic is toxic for cats!), yet there is not the same degree of established effectiveness as compared to vacuuming and drying agents. Garlic is a GRAS (Generally Recognized as Safe) ingredient according to AAFCO (American Association of Feed Control Officers). Garlic also has anti-inflammatory benefits, as well as anti-infectious organism and anti-cancer properties.

Additionally, reducing the ability for outdoor creatures (raccoons, skunk, rabbit,etc.) to enter your yard, closing windows and doors, repairing construction defects that could harbor fleas, and preventing your pets from going to areas potentially infested with fleas (boarding facilities, dog parks, etc.) are other ways humans can prevent a parasitic invasion.

Dr. Patrick Mahaney

Image: Steve Yager / via Shutterstock

Patrick Mahaney, VMD, CVA, CVJ


Patrick Mahaney, VMD, CVA, CVJ


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