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External parasites live on the outside of a dog’s body. According to the American Veterinary Medical Association (AVMA), at some point in their lives, many pets experience discomfort caused by external parasites, such as fleas, ticks, or mites, on their skin or in their ears. These parasites can cause serious skin problems or carry disease. Modern medicines make treatment, control, and prevention of many external parasites much easier than in the past.


Fleas are tiny wingless insects that feed on mammals, including dogs. They thrive in warm, moist weather and may be seasonal or active all year, depending on the region of the country. Fleabites make some dogs so miserable that they bite and scratch themselves raw. Fleas may cause young dogs to become anemic. Also, dogs can become infected with tapeworm by swallowing fleas carrying tapeworm eggs.

You may be able to see the dark fleas scurrying around on your dog’s skin. Their favorite spots include the base of the ears and the rump. Look closely in sparsely haired places, like the groin. Another way to diagnose fleas is to part the fur and look for black specks the size of poppy seeds. These specks are flea feces, composed of digested blood. If you’re not sure whether you’re looking at “flea dirt” or just plain dirt, place some on a damp piece of white tissue. After a minute or so, a small red spot or halo will become apparent if it’s flea feces, since the blood rehydrates and diffuses into the tissue.

If you see evidence of fleas on your dog, it’s essential to get rid of them as quickly as possible, before the population grows. Hungry fleas sometimes bite humans, too, leaving small, red, itchy bumps most commonly on wrists and ankles. Your best bet is to protect your dog from becoming infested with fleas in the first place by using a preventative product your veterinarian recommends.


Ticks can cause a number of serious illnesses, and canine tick-borne diseases, including Lyme disease, Ehrlichiosis, and Rocky Mountain Spotted Fever. There are more than 800 species of ticks worldwide, and they all feed on the blood of mammals, birds, and reptiles. Ticks go through four life stages, which can take up to three years to complete. Once the eggs hatch, they must eat blood to survive.

The Kansas State Veterinary Diagnostic Laboratory reports that annually, thousands of dogs and humans are infected with tick-borne diseases, and that rate is climbing due to the increasing range of the various tick species, encroachment of wildlife species into the traditional urban environments, and an increase in pet travel. The wide variation in the disease onset, the variable clinical signs exhibited, and the response to therapy can make a definitive diagnosis of the specific tick-borne disease difficult. They suggest that a tick-borne disease screening panel can be very helpful in identifying the type of tick-borne infection. Disease is not spread between dogs and humans; a direct bite from a tick is the only way to become infected.

Check your dog for ticks daily after he spends time outside, and whenever you see a tick, take it off immediately. The best way is to numb the tick with rubbing alcohol or petroleum jelly and pull it off with fine-point tweezers. Once removed, kill the tick by putting it in a container of alcohol. Prevent an infestation by treating your dog with a medication, dip, spray, or powder recommended by your veterinarian.

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Lice and Mites

Lice and mites are microscopic organisms that feed on your dog’s skin and cause itching, hair loss, and infection. Generally speaking, lice and mites are two different species, but they function and behave in a very similar way.

Lice live in a dog’s hair and can be killed with an insecticide used for ticks or fleas. Note that dog lice and human lice are different species — dog lice need dog blood and human lice need human blood. While humans may occasionally be bitten by dog lice, they will not get an infestation.

Various kinds of mites inhabit different areas of the dog, and the problems they cause are generally known as mange.

Demodectic mange causes hair loss around the forehead, eyes, muzzle, and forepaws. These microscopic mites aren’t highly contagious, although mother dogs can pass them to puppies. They appear as redness and scaly skin around the mouth and eyes and are unlikely to be itchy. Some cases clear up on their own, while others require special shampoos or oral medications. When an adult dog develops demodectic mange, the dog usually has another medical condition that is compromising the immune system.

Otodectes or ear mites are fairly common in young dogs. Your dog may have mites if he shakes his head and scratches his ears. You may also see a thick brown discharge. Excessive scratching can result in sores or broken blood vessels. Ear mites are contagious and can travel from the ears of an infected dog to other dogs close by. Your vet will treat your dog with medication, usually in the form of ear drops, and ear cleaning.

Scabies or sarcoptic mange is highly contagious and affects humans as well as dogs. It’s caused when microscopic mites burrow into the dog’s skin and cause intense itching. Scabies usually affects the ears, elbows, legs, and face. Hair loss, skin rash, and scabs are common. Veterinarians will prescribe medications to kill the mites, relieve itching, and heal the skin. Careful cleaning of the dog’s bedding and environment is also critical.

Cheyletiella mites cause what is called “walking dandruff” on a dog’s head, back, and neck. This mite also causes itchy red spots on humans. It’s uncommon, but highly contagious and treated by clipping long hair, using topical insecticides, and repeated medicated baths.

How to Prevent and Treat Dog Parasites

When it comes to preventing and treating the external parasites that can plague your dog, the AVMA recommends that dog owners:

  • Use a preventative treatment such as a topical medicine, a flea & tick collar, or another method.
  • Look for fleas, ticks, and coat abnormalities any time you groom your dog or when you return home from areas that are likely to have higher numbers of these parasites.
  • Consult your veterinarian if your pet excessively scratches, chews, or licks the coat, persistently shakes the head, or scratches the ears.
  • See your veterinarian as soon as possible to find out the best treatment for your dog. Prompt treatment of parasites lessens your pet’s discomfort, decreases chances of disease transmission, and may reduce the degree of home infestation.

This article is intended solely as general guidance, and does not constitute health or other professional advice. Individual situations and applicable laws vary by jurisdiction, and you are encouraged to obtain appropriate advice from qualified professionals in the applicable jurisdictions. We make no representations or warranties concerning any course of action taken by any person following or otherwise using the information offered or provided in this article, including any such information associated with and provided in connection with third-party products, and we will not be liable for any direct, indirect, consequential, special, exemplary or other damages that may result, including but not limited to economic loss, injury, illness or death.

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