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Flea Infestation In Dogs – Treatment & Prevention

Flea Infestation In Dogs

What Is Flea Infestation In Dogs?

Fleas are wingless, parasitic insects that feed off the host's blood. Fleas are the most common canine external parasite. There are more than 2000 types of fleas all over the world. Ctenocephalides canis (the dog flea) and Ctenocephalides felis (cat flea) are the most common ones. Paradoxically, cat fleas are the most common fleas found on dogs. They can not only transmit infection but also can cause itching and irritation as well.

Fleas have four life stages - egg, larva, cocoon or pupae, and adult. If not properly treated, they can survive in your dog for a long time. Adult females lay their eggs 1 to 2 days after their first blood meal. On average, every day 40 eggs are laid by female fleas. For the eggs to develop, it can take anywhere from two days to two weeks and they will hatch only under the right environmental conditions. The eggs will take a longer time if temperatures are cold and dry.

After hatching a flea egg, emerging larvae readily feed on pre-digested blood (flea dirt) that the adult fleas pass along with organic debris. After 5-20 days of hatching from their eggs, larvae will spin a protective casing called a cocoon and encase themselves to develop into a fully-developed flea, which takes approximately 6 to 20 days. When the host is nearby, the larva may stay latent in this cocoon for up to six months. Cocoons cannot be easily removed by sweeping or light vacuuming as they have a sticky outer coating that helps them to hide deep in the carpeting.

After a flea has emerged from the protective casing, adult fleas need blood meal from the host. Soon after the first meal, female fleas will breed and start laying eggs within a few days. New adult fleas are very dark in color and have a flat-bodied appearance. After the initial feeding from the host, they will become lighter in color and larger, changing to the more typical flea shape.

Flea Allergy Dermatitis (FAD) is the leading cause of allergic reactions in dogs. Also called fleabite hypersensitivity, this is an allergic reaction produced in dogs in response to the injection of antigenic material (flea’s saliva) from flea bites.

The clinical signs can be seasonal or occur year-round depending on the geographic region. In the regions in which there are defined cold weather seasons clinical signs are most common.

Symptoms Of Flea Infestation In Dogs

  • Pruritus (Scratching, Itching, Rubbing, Licking)
  • Reddening and thickening of the skin
  • Papulo-crustous lesions and erythema may be present
  • Greasy skin
  • Patchy or inconsistent hair loss
  • Secondary bacterial and yeast infections
  • Fleas or flea dirt
  • Large amounts of black debris in ears

Treatment Options For Flea Infestation In Dogs

Flea allergy dermatitis treatment is multifactorial.

  • Allergy injections, also known as desensitization
  • Topical adulticides: (fipronil, imidacloprid, metaflumizone, selamectin, indoxacarb)
  • Oral adulticides: (nitenpyram, spinosad)
  • Adulticides with insect growth regulators: pyriproxyfen and methoprene
  • Insect development inhibitors: lufenuron
  • Antihistamines - Chlortrimeton, Benadryl, Atarax, Clemastine, Claritin and Zyrtec
  • Pruritus: pruritic skin disease via antipruritic drugs
  • Antibiotics and Antifungal Medications - these are required to treat secondary infections
  • Corticosteroids and Immunosuppressive Agents - Cortisone (dexamethasone, prednisone, prednisolone) and Cyclosporine (Atopica)

Home Remedies For Flea Infestation In Dogs

  • Keep the dog clean and dry
  • Use a pet-friendly anti microbial wipes
  • Clean food and water bowls daily
  • Use ointments/Creams to ease itching & irritation
  • Use Cold compresses when needed.
  • For a chewy or scratchy dogs, Consider using an inflatable/ Elizabethan collar

Prevention Of Flea Infestation In Dogs

  • When you find out your dog is allergic to fleas allergy, avoidance is the best method of control.
  • Discourage your dog from roaming freely in grassy forested pathways and wooded tick-infested areas.
  • Keep the skin and fur clean. Use medicated wipes containing a skin disinfectant.
  • Use clean paper towels (or a clean washcloth) and medicated dog shampoo (e.g. Nolvasan medicated shampoo).
  • Dogs with skin folds can be cleaned daily with a clean, damp cloth, shampoo, wipes, ointment, lotion, spray, skin cleanser, etc.
  • If you bathe your dog less often, you’ll have to spot clean the area daily to get rid of trapped food and moisture.
  • Consult with your veterinarian dermatologist for hypoallergenic vaccinations.

Affected Dog Breeds Of Flea Infestation

There is no sex predisposition.

Golden Retriever, Labrador Retriever, Shar Pei, Dalmatian, Wirehaired Fox Terrier, Old English Sheepdog, Boxer, Boston Terrier, Scottish Terrier, West Highland White Terrier, Lhasa Apso, Shih Tzu

Causes And Types Of Flea Infestation In Dogs

1. Causes:

Dogs get infected by fleas by

  • Exposure to other flea-infested animals
  • Pet daycare, dog park, or from the boarding facilities
  • Outdoors during warm, humid weather
  • Wandering in grassy or wooded areas

2. Types:

Flea bite hypersensitivity reactions bear the trademarks of cutaneous basophil hypersensitivity reactions, immediate (type I), and delayed (type IV) hypersensitivity reactions.

Type I hypersensitivity: This is an immediate hypersensitivity reaction. It is a humoral response aggravated by re-exposure to a specific type of antigen. Immunoglobulin E binding to mast cells triggers the reaction which leads to the release of inflammatory mediators, such as histamine.

Type IV hypersensitivity: They are delayed-type hypersensitivity that is cell-mediated. This involves interactions of antigen-specific effector T cells. Copious amounts of lymphokines are activated which results in the release of pruritogenic inflammatory mediators.

Basophil hypersensitivity: This lymphocyte-mediated hypersensitivity is a transient delayed-type reaction. This sequence of reactions includes basophils in the papillary dermis and less indurated erythema.

3. Mortality:

There is no documented mortality due to this condition.

4. Diagnosis:

  • Complete blood count, chemistry panel
  • Specialized blood tests (IgE blood tests).
  • Intradermal testing (IDT)
  • Serological allergy testing using ELISA
  • Flea saliva antigen (FSA)

5. Prognosis:

The prognosis for flea allergy dermatitis is really good. As the existing condition is not life-threatening, no rigorous treatment is usually necessary. However, relapse will be a problem following medical treatment in affected dogs. Proper hygiene and home care are the best defenses against future recurrences.

When To See A Vet For Flea Infestation In Dogs?

Contact your vet right away, if you notice any of the following:

  • Pruritus (Scratching, Itching, Rubbing, Licking)
  • Reddening and thickening of the skin

Food Suggestions For Flea Infestation In Dogs

A well-balanced diet is a precautionary measure for this condition.

  • Avoid providing meals that might have fats
  • Omega3 fatty acids- Mackerel, Salmon, Herring, Sardines
  • Lean meats, such as chicken breast, sirloin, or pork
  • Leafy green vegetables, cauliflower, and broccoli
  • Low fat, high protein foods- White-Fleshed Fish, Skinless, White-Meat Poultry, Beans, Peas, and Lentils


Flea infestation prognosis is good with treatment. The recovery time for dermatitis is different for every dog. Monitor your dog for any unusual symptoms. Don’t delay in reporting any flare-ups of symptoms to your veterinarian.

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