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Animal Skin and Allergy Clinic Blog

Fleas and Mites and Lice, Oh My! Ectoparasites and Pets

A big fluffy puppy scratchingIt is autumn and the pollens are flying. Many pet owners are quick to blame their pet’s itchiness on seasonal allergies, but it is important not to jump to conclusions too quickly. Many itchy pets can blame critters such as fleas, mites, and lice for their woes. If your pet is unusually itchy this fall, or if the normal treatments aren’t working, it is important to take a step back and determine whether your pet’s skin might be harboring an unwanted visitor. Read on to learn more about ectoparasites and pets.


Fleas are one of the most common (and definitely one of the most annoying) external parasites that we deal with. We often see flea populations explode in the fall, as the optimal temperature for flea development is between 70 and 86 degrees Fahrenheit. In fact September and October are often the height of flea season. Fleas can continue to be a problem in the cooler months as well, especially if they have made it indoors. If a pet (or person) carries a flea into the home, that flea can lay about 50 eggs in one day. It is easy to see how the flea population indoors can get out of control quickly. Fleas can be annoying and cause itching in any pet, but some animals actually experience an allergy to flea saliva called flea allergy dermatitis. These pets can be extremely miserable even if a large infestation is not present. We can often find evidence of fleas on our patients, however even if we don’t we will likely recommend treating for fleas to eliminate them as a cause of itching.


Another ectoparasite commonly found on our four-legged friends is skin mites. These microscopic creepy-crawlies live on the skin and can cause some pretty intense itching. The layman’s term for a mite infestation is mange. There are two main types that we see:

  • Sarcoptic mange – Sarcoptic mange, also called scabies, is caused by a mite that burrows into the skin and can be contagious. Pets with scabies are often very itchy. Common locations to find the mite include the ear flaps, elbows, hocks, and hairless areas of the belly. Because the mites can be hard to find, we may treat for this condition if it is suspect even if we can’t demonstrate an infection.
  • Demodectic mange – Demodectic mange, or demodex, is caused by a specific mite that lives in the hair follicle in the dog. Most dogs have this mite in their skin. Normally the host defenses keep the mites from causing any problems. However, if something happens to impair the normal immune system the mites are allowed to take over. This can happen in young puppies when their immune system is not completely developed or in adults when drugs or disease suppress the normal immune function. It is typically not contagious.
  • Mite infestations are typically diagnosed with a plucking of hairs or by a skin scrape in which the surface of the skin is gently scraped with a surgical blade. The hairs plucked or scrapings are examined under the microscope for evidence of mites. Sometimes a surgical biopsy will reveal the presence of demodex mites.


Pets can get lice, just like people! While the species that plague humans are not the same ones that affect our dogs and cats, they are the same organism. Lice (on pets) are fairly uncommon here in the United States, but we do find them on occasion. These ectoparasites lay eggs (nits) on the hair shafts. On close examination you can see the little white nits on the hair. A trained eye can see these organisms easily. Luckily they are not too hard to treat with environmental control and treatment with special shampoos and topical insecticides.

What You Need to Know About Ectoparasites and Pets

Most ectoparasites such as fleas, lice and even mites are controllable using one of the newer oral monthly parasite preventative products. Sometimes, however, these unpleasant creatures make their way onto our pet’s skin even when preventative measures are taken. It is important when you notice a skin problem on your pet to have it evaluated right away. While it is easy this time of year to blame itching, hair loss, and redness on seasonal fall allergies, it is vital to be sure that nothing else is going on. Pets who have an ectoparasitic infection often do not respond, or will worsen, with typical allergy treatments. When it comes to ectoparasites and pets, it is also important to diagnose the problem early as they all reproduce rapidly, making them harder and harder to control with each day that passes.

If your pet is a little extra itchy this fall, be sure to make an appointment to have him or her evaluated. We are happy to help identify the problem and recommend the best course of treatment.

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