Logo Whiskers, Paws and Love Inc.
Articles WPL Friends Donate Volunteer Shirts Paws Together®

Diseases That Commonly Affect Dogs: Parasites

Author Photo

Whiskers, Paws and Love Inc. Team

Blog Post Image

Table of Contents


    FLEA ALLERGY DERMATITIS (FAD), the most common skin disease in dogs in the US, is caused by an allergic reaction to flea saliva resulting in skin irritation and infections. This type of allergy is different from normal itchiness in response to a bug bite. Dogs that have other known skin allergies are more likely to also have a flea allergy because their immune system is hypersensitive. When adult fleas bite a dog, they inject saliva into the skin before falling off, and it is the proteins in the flea saliva that result in itch and inflammation in dogs that are allergic. A single flea bite can cause a skin flare-up within 15 minutes. The itching will be intense and may last for up to two weeks. Even if you haven’t seen any live fleas on him, flea bites may still be the cause of your dog’s skin problem. Though flea allergies are more common in warmer months, fleas can live year-round indoors. Once they lay eggs, new fleas hatch and then lay more eggs, which means your pet is constantly exposed.


    SYMPTOMS include: redness and mild to severe itching; crusts or small red or pink raised bumps that look like pimples and can become scabs; “hot spots” or infected sores (usually located on the dog’s legs, hind end and tail); a rash or raw, irritated, or bleeding areas on your dog’s body (they usually have it near their back legs, stomach, or tail area); constant itching, biting, rubbing, clawing, or grooming; and hair loss (especially in areas where the bites happened, often starting around the base of the tail and back legs and spreading along the dog’s back towards his head)


    DIAGNOSIS is difficult because fleas don’t actually live on your dog. They live in carpets, bedding, and other surfaces in your home and outdoors, and they jump onto your dog to eat. If you took your dog out for a walk and he was bitten by a flea which fell off, that one bite could cause a skin reaction that lasts up to a week. Flea bites on dogs can also be hard to see - they appear as small, raised, red lumps that disappear within a couple of days. Some dogs have a raised, red rash on hairless areas of their skin such as in the groin or armpits. Another way to check for fleas is to use a flea comb to search for flea dirt (the droppings that fleas leave behind). Flea dirt looks like pepper, and it can be distinguished from regular dirt because it will leave a blood smear on wet paper. Although fleas and flea allergies are common, your dog could have another health problem, like a tick bite. It’s important to get the right diagnosis before starting treatment.


    TREATMENT relies on a two-pronged approach of (1) ridding your dog of fleas and (2) treating the dermatitis and skin lesions. There are many topical treatments, oral medications or shampoos that kill fleas on your dog. Topical flea treatments (like Frontline or Revolution), and oral pills or chewables (like Bravecto and Capstar) kill adult fleas and break the flea life cycle. It is important to treat all animals in the household for fleas even if the others don’t have a flea allergy. It is best to work with your vet to pick flea prevention products that are best for all your pet’s needs. While many vet-approved or prescribed sprays and topicals are considered safe, some pets may still be sensitive to their ingredients. Stop any treatment if you notice that it’s causing irritation or another kind of allergic response. Your vet is also likely to prescribe a topical, oral, or injected medication to ease the itching and inflammation, as well as treatment for any sores or lesions on your dog’s skin; and he may perform skin scrapes or swabs to look for other parasites or bacterial skin diseases as well as allergy testing. Dogs with severe flea allergies or with combined skin allergies may benefit from desensitization (or hypo-sensitization) which was discussed in Part 1 of this article. Desensitization therapy doesn’t cure the flea allergy, but it can help dogs with severe allergies react less to flea antigens. It’s possible for FAD to improve within two weeks of treatment, particularly if the underlying flea infestation has been successfully eliminated.

    Home remedies you can try: oatmeal (to calm redness in the skin and soothe the itch), Vitamin E (to boost the production of collagen and promote the regeneration of skin cells, and it is also a powerful antioxidant that helps protect skin cells), rosemary extract (which has anti-inflammatory properties), coconut oil (to moisturize the skin and help reduce inflammation), avocado oil (to encourage skin collagen production and reduce inflammation), hemp seed oil (to help repair skin cells and reduces inflammation). A cool bath can also provide relief (but it is important to remember that many flea products require the coat to stay dry for 48 hours after application). You can help manage the itch by using a cone collar to prevent your pet from scratching

    Home remedies that are NOT recommended for the prevention of fleas or for the treatment of flea allergies: citronella, eucalyptus, peppermint, and tea tree oil to repel fleas because they have not been proven to kill fleas, nor to break the flea life cycle, and they are likely to be irritating to inflamed skin; garlic and onions because they are toxic to dogs; essential oils and products that contain them because they irritate the skin, especially the skin of a dog with a flea allergy; flea shampoos and sprays that contain alcohol and other chemicals which could make a rash or wounds worse; human antihistamines because they not strong enough to ease inflammation for many pets with a flea allergy.


    Every adult flea that lands on your dog and bites to feed will lay eggs. Each adult flea can lay up to 50 eggs per day and some fleas have developed resistance to medications and insecticides. The eggs fall from your dog’s fur and land in the environment around your dog before hatching into larvae, and pupae, and then becoming adults ready to repeat the life cycle. A single adult female flea can produce up to 2,000 eggs in her lifetime. These eggs may be laid in any number of places (in your dog’s fur, on your dog’s toys, in his bedding, in your bedding, in couch cushions, deep in the carpet, in the dust and debris in small nooks and crannies of hardwood floors, in any crevices and tight spaces, in tall grass, et cetera). Fleas usually evolve from egg to adult within 2 to 3 weeks and they can live for up to 100 days. Since the flea has multiple life stages (egg, larvae, cocoon, adult) it is assumed all these stages are present throughout your house when there are fleas.

    As with most things, an ounce of prevention is better than a pound of cure! After you treat your dog (and other pets) both to remove fleas on him and to prevent any fleas that bite him from reproducing, your next step is to treat the environment to eliminate fleas permanently. Depending on your pet’s boundaries, the environment may include your house, your car, and your yard. We don’t recommend that you use insecticides or other chemical treatments such as aerosol sprays and foggers to kill fleas. Even if you’re extremely cautious and you and your pet(s) stay out of the house for hours after using them, many are toxic to humans, pets, and the environment. We also don’t recommend flea collars which can be highly toxic and irritate your dog’s skin.

    Instead of risking your dog’s health as well as your own by using dangerous chemicals, we recommend the using the following tested and proven effective method for cleaning the house:

    • A powerful vacuum cleaner that uses bags
    • At least 21 vacuum bags
    • Moth balls (to kill the fleas before they can crawl out of the vacuum cleaner)
    • A flea trap *
    • 2-4 weeks of hard work, persistence, and patience

    Put a few moth balls into the vacuum cleaner bag and vacuum all flooring, upholstery, mattresses, larger rugs, and chair and sofa cushions every single day for a two-week period, followed by every other day during the third week. Seal up the vacuum bag and toss it in the trash after each cleaning session. Thoroughly wash your dog’s bedding and toys, your bedding, and throw rugs in hot, soapy water every couple of days (make sure any cleaning chemicals or soaps used are pet-friendly) and dry them on the highest heat setting. You can also use a steam cleaner for carpets and upholstery, including pet beds. The combination of high heat and soap is the enemy of fleas in all stages of life. Set out the flea trap and keep it plugged in 24 hours a day. Pay special attention to any spots where your pet usually lies down or spends a lot of time. Move the flea trap around until you start catching fleas. Since that is the location fleas are congregating, you need to run the vacuum over that area two or three times during each cleaning session. If your dog travels in the car, you also need to vacuum inside the car as part of your cleaning routine.

    We recommend that you limit your dog’s time playing on the lawn if you have a flea infestation. Other tips for preventing fleas in our yard are:

    Mow your lawn regularly and rake the exposed surfaces thoroughly (bag the contents rather than adding them to your compost pile); avoid over-watering, which can create the exact humid conditions for fleas to thrive; remove debris, such as dead leaves and twigs, from flower beds and from under bushes; expose as much of the shady areas to sunlight as you can; spread cedar chips under bushes and on flower beds where your dog might lie down; encourage wild animals like opossum, mice, and squirrels to move elsewhere since they carry fleas (set up barriers in the yard, put up bright lights, leave rags soaked in cider vinegar, or play loud music - unless it bothers the neighbors!)

    The prognosis for pets with FAD is good if flea bites are prevented. After that has been accomplished, the long-term goal for managing FAD includes an effective year-round flea preventative for all pets in the household and environmental control to reduce exposure to fleas.

    Flea traps consist of a small light bulb that is usually suspended over a sticky glue paper (or it can be a dish of soapy water). The adult flea is attracted to the warmth of the light, and it jumps toward it and falls onto the sticky board where it dies. When you use a flea trap you will only catch adult fleas (flea traps have no impact on eggs, larval and pupal flea stages). However, they are still valuable because you will find out where the fleas are congregating and laying their eggs so that you can pay special attention to vacuuming those areas. Leave the flea trap plugged in 24 hours a day as a preventive measure so that you can catch a new batch of fleas before they can reproduce.