Parasites are an annoying fact of life for our dogs. Parasites can cause a range of problems, from bothersome scratching to more serious medical issues, such as infections and dangerous or even deadly diseases. How dangerous these problems are depends on the type of parasite, the degree of infection or infestation, and your dog's reaction to the parasite.

Most parasites that affect dogs pose no risk for humans. However, a few parasites, like sarcoptic mange mites, are zoonotic, meaning they can be transmitted from animals to humans. Your veterinarian can recommend methods to prevent, treat or control many canine parasites to reduce the chance of human exposure and to keep your dog healthy.


Adult fleas are small, flat, wingless parasites that feed on the blood of their hosts. Fleas can bite humans, although they prefer dogs, cats and other mammals. Because fleas prosper in warm, humid environments, temperature and humidity changes can affect the length and success of their life cycles. The adult flea spends all of its time on a pet; this is the life cycle stage that you are most likely to encounter. Prevention is the best way to keep fleas away from you and your dog.

Signs and Complications of Flea Infestation

Scratching may be the first sign that your dog has a problem with fleas. Other signs include:

  • Hair loss
  • An unusual amount of chewing and licking
  • Black specks found on the skin and coat or on your dog's bedding

Flea bites can also trigger secondary bacterial infections and more serious allergic reactions, including flea allergy dermatitis (FAD) - an uncomfortable inflammatory skin disease. Because fleas feed on blood, blood loss can result in anemia and even death with severe infestations, with puppies at particular risk. In addition, fleas can transmit tapeworms, and there are occasional reports of children being infected following ingestion of an infected flea.1

What You Should Know About Fleas

It is important to realize that the fleas you see on your dog are only a small percentage of the entire flea population. Fleas lay eggs that fall off your dog into your home, particularly where your dog spends most of its time (such as in bedding). These eggs hatch into larvae, which spin cocoons and become pupae. The pupae develop further and emerge as adult fleas in response to animal activity.

In the right environment, fleas can breed indoors all year, and adult female fleas may produce up to 40 or 50 eggs per day.

How to Check for Fleas on Your Dog

Look for irritated areas on your pet's back, abdomen, neck and rump and on the inside of the thighs. You can also check for flea "dirt" (which is actually flea feces) by running a fine-toothed metal flea comb through your dog's hair and wiping off the comb with a wet white paper towel. If any black flecks turn reddish (because of your dog's blood in the flea's feces) when wet, you've found flea dirt.

What You Can Do to Help

If you think your dog has fleas, call your veterinarian. It's important to remove fleas not only from your dog, but also eliminate them from your dog's environment. Your veterinarian can recommend treatment such as REVOLUTION® (selamectin) to kill fleas and prevent flea eggs from hatching. REVOLUTION will help resolve infestations, and prevent flea infestation.  In addition, REVOLUTION in clinical trials was shown to improve the signs associated with flea allergy dermatitis. Ask your veterinarian about REVOLUTION.

Once you apply REVOLUTION, adult fleas will be killed and flea reproduction will stop by preventing eggs from hatching. But remember that the fleas you see on your dog are only a small percentage of the problem. For an established flea infestation to be resolved, all of the stages of the infestation must be considered. It may take several months for lifestages, including eggs, larvae and pupae to mature and be removed from the environment. This can result in a small number of adult fleas being seen on your dog periodically as the
environmental stages are exhausted. When the environmental flea population has been destroyed, the problem will end, but keep using REVOLUTION to prevent a new flea
infestation from beginning.

Preventing future infestations is far easier than treating (and having to deal with) a flea
problem once the parasites are established on your pet and in your home. Protect your pet
and your family by keeping your dog on REVOLUTION year-round.


This parasite got its name because the adult worm lives in or near a dog's heart, however, heartworms can also be found in a pet's lungs. Adult worms look a lot like cooked spaghetti - long, white and slender-and can grow up to 12 inches in length.1

Mosquitoes transmit heartworms. A mosquito bites an infected animal and takes in microfilariae, which grow to become infective, immature worms inside the mosquito. The infected mosquito then transfers the immature worms to a host, such as a dog. The worms then live inside the dog's tissues, eventually maturing into adult worms and migrating to the heart and large blood vessels inside the lungs.

Left untreated, heartworm disease can kill a dog and many pet owners don't even realize their dog may be infected. Fortunately, canine heartworm disease is preventable, and heartworm prevention in dogs is safe, effective and easy to administer. Preventing heartworm infection is also far easier than treating it. By keeping your dog on a heartworm preventive year-round, you'll be protecting your pet from these parasites and avoiding the cost - both financial and emotional - of dealing with heartworm treatment.

Signs and Complications of Heartworm Disease

In the early stages of the disease, many heartworm-infected dogs show no visible symptoms. But the continued presence of adult worms can cause changes that damage the heart and lungs. If left untreated, the reaction to adult heartworms can result in heart failure.

Signs that your dog might have heartworm disease include:

  • Cough
  • Difficulty breathing
  • Exercise intolerance
  • Lethargy
  • Loss of appetite
  • Weight loss
  • Swollen abdomen (caused by fluid accumulation)

What You Should Know About Heartworm Infection

Heartworm infection has been diagnosed in all 50 states.2 The damage that heartworms cause depends on the number of worms present and the dog's activity level. Although signs of heartworm disease can have an acute (sudden) onset, chronic (long-term) infection is more common. If not promptly and properly treated, infection can damage the dog's heart, lungs, liver and kidneys. Canine heartworm disease is much easier to prevent than to treat.

What You Can Do to Help

The American Heartworm Society recommends that all dogs receive a heartworm preventive year-round.2 Your veterinarian can recommend appropriate testing and ongoing preventive treatment such as REVOLUTION. Monthly administration of REVOLUTION prevents heartworm disease in dogs and in puppies as young as 6 weeks. Ask your veterinarian about REVOLUTION.

Ear Mites

These tiny, troublesome pests generally live in a pet's ear canal. They can also migrate to other areas on the skin. Left untreated, ear mites can cause dogs' severe discomfort, but are usually easy to get rid of with prompt and proper veterinary treatment. Prevention is the best plan to prevent your dog from suffering from these unpleasant parasites.

Signs and Complications of Ear Mite Infestation

Ear mites can cause inflammation of the external ear. Signs of ear mite infestation include:

  • Intense/frequent head shaking
  • Scratching and pawing at the ears
  • Itchy skin around ears, head and neck
  • Crusting around the outer ear or in the ear
  • Red and painful ears
  • Possible crust and scales on the neck, rump and tail

Infestation by ear mites can be complicated by secondary bacterial infections. Dogs with ear mites may have ears with an unpleasant odor and a dark, crusty brown, waxy discharge that looks like coffee grounds.

What You Should Know About Ear Mites

Ear mites are highly contagious and are easily spread from pet to pet through direct contact. Some animals may harbor ear mites, but not show any clinical signs of infestation.

On very rare occasions, people have been infested with ear mites.1*

What You Can Do to Help

REVOLUTION® (selamectin) is highly effective against ear mites. All pets within a household should be treated with an appropriate product, not just the visibly affected dog. Monthly use of REVOLUTION treats and controls ear mite infestations in dogs and in puppies as young as 6 weeks.

Even better, simply give your dog a monthly dose of REVOLUTION to keep these irritating parasites away from your pet in the first place. Ask your veterinarian about REVOLUTION.

Sarcoptic Mange (Scabies)

Sarcoptic mange, or scabies, refers to skin disease (dermatitis) caused by microscopic mites that burrow under a dog's skin and lay eggs. Skin problems caused by mites will continue if the life cycle is not broken, which is why treating and controlling scabies is so important.

Signs and Complications of Scabies Infestation

Sarcoptic mites can cause your dog severe discomfort. Signs of infestation include:

  • Intense itching, scratching and biting, especially around the ears and elbows.
  • Red bumps, reddened or inflamed skin
  • Crusty scabs or scales
  • Hair loss

If the infestation is not treated promptly, it may spread over a larger area of the dog's body. Dogs with scabies may also develop secondary bacterial and yeast infections.

What You Should Know About Sarcoptic Mites

Scabies mites tend to prefer areas on a dog with no or little hair, such as ear margins, elbows, hocks, and underside. Although dogs are the primary host, mange is easily transmitted to other animals, including humans, through direct contact. Mites can live in the environment for 2-6 days at room temperature, and this can be a source of infection for other animals in the house.1 Some animals may be carriers of these mites, but not show any clinical signs of disease.

What You Can Do to Help

Your veterinarian can recommend REVOLUTION® (selamectin) for the treatment of current scabies infection and control over future infections in dogs and in puppies as young as 6 weeks. All dogs within the household should be treated, not just the visibly affected animal. For peace of mind regarding these unpleasant parasites, give your dog a monthly dose of REVOLUTION.

Ask your veterinarian how REVOLUTION can keep your dog safe from scabies and other harmful parasites.


The American dog tick is found throughout much of the United States. Because ticks can cause serious illness in dogs, control of tick infestations is the best way to keep your dog safe.

What You Should Know About American Dog Ticks

As the name suggests, this tick's preferred host is dogs. The American dog tick is a primary carrier of Rocky Mountain spotted fever, a disease that can cause canine tick paralysis, which can be fatal in dogs.

What You Can Do to Help

Keeping your dog safe from ticks is important. Even if you avoid wooded areas and carefully check your dog after being outside, it's still easy to miss ticks that may have crawled under the fur or in the ears. Help keep your dog safe from ticks and tick borne diseases by giving your dog a monthly dose of REVOLUTION® (selamectin). With monthly dosing, REVOLUTION controls American dog tick infestations in dogs and in puppies as young as 6 weeks.

Ask your veterinarian how REVOLUTION can protect your dog from ticks and other harmful parasites.

IMPORTANT SAFETY INFORMATION:  Do not use REVOLUTION on sick, weak, or underweight dogs. Use only on dogs 6 weeks and older. Prior to administration, dogs should be tested for heartworms. In people, REVOLUTION may be irritating to skin and eyes. Wash hands after use.
See full Prescribing Information.

References and for more information:

1. Companion Animal Parasite Council (CAPC). CAPC Recommendations for Parasites: Fleas. Updated September 2017. Accessed July 10, 2018.

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