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Canine Parasites

Fleas, ticks, worms and more


Parasites come in many sizes, shapes and levels of "severity" for our pets. This collection of parasites are those commonly found on dogs and other species, sometimes affecting humans (called a zoonotic disease).


1. Fleas

Electron micrograph image of a flea
Image © Center for Disease Control (CDC)

Fleas. They make pets' lives miserable, and humans begin to itch just at the thought of them. Vets are often asked what pill, drop, dip, collar, or shampoo works the best to get rid of these persistent parasites. The answer is that there is no single method or insecticide that will completely eradicate (or at least control) a flea problem. The flea life cycle is fairly complex, and understanding the various stages will make it easier to get rid of them.

2. Heartworm

Mosquito by tanakawho on Flickr
by tanakawho on Flickr

Heartworm disease is caused by a parasite that lives mainly in the blood vessels of the lung and in the heart, transmitted by mosquitoes. Heartworm disease has been seen in several species, but dogs are very susceptible. It can be fatal and is difficult to treat, but fortunately heartworm disease is easy to prevent.

3. Ear Mites

Image (taken through microscope) of ear mites sampled from a cat's ear. Credit: Wikimedia Commons /
Credit: Wikimedia Commons / Caroldermoid

Ear mites are tiny parasites that live out their life cycle mostly inside the ear canal. They are quite common, and can cause severe irritation and itchiness of the ears.

The most common ear mite of cats and dogs is Otodectes cynotis, and therefore an infestation with ear mites is sometimes called "otodectic mange."

4. Demodex Mite

Demodex canis taken through a microscope at 400x magnification - Wikimedia Commons / Joel Mills
Wikimedia Commons / Joel Mills

Demodex mites are microscopic normal inhabitants of dog skin. In a healthy animal, the mites are few in number and do not cause skin problems. In some cases though, the mites can take over, leading to a condition commonly called "mange" or demodicosis. Learn about the types of mange and various treatment options for this skin parasite.

5. Cheyletiella Mites

Cheyletiella mite close-up view By Kalumet on Wikimedia Commons
By Kalumet on Wikimedia Commons

Cheyletiella are mites that live on the skin, causing irritation, dandruff, and itchiness. A distinguishing feature of this mite species are the large, claw-like mouth parts. These mites can be found quite commonly on cats, dogs and rabbits, and other species. Though humans are not a natural host for this parasite, Cheyletiella mites can happily live on humans for a while, causing an itchy rash.

6. Babesia Protozoa

Adult deer tick, Ixodes scapularis - Photo credit: Scott Bauer (USDA ARS)
Photo credit: Scott Bauer (USDA ARS)

Babesia infections occur in dogs and other species, and are transmitted mainly by ticks. Babesia are protozoal parasites that attack blood cells, though the severity of illness varies considerably depending on the species of Babesia involved, as well as the immune response of the infected dog.

7. How to Remove a Tick From Your Pet Or Yourself

A male "brown dog tick" (Rhipicephalus sanguineus) - credit James Gathany/CDC
credit James Gathany/CDC

There are many ideas about the best way to remove a tick, one of the most common tricks being to put a lit match on the tick to make the tick "angry" enough to back out on its own. The truth is, this can actually make things worse for you and the tick; injecting more foreign material into you (or your pet) from the tick. Early removal of the tick is very important. Find out how to check for and remove ticks safely in this how to.

8. Cuterebra Parasite - An Opportunistic Parasite

First instar larva of Cuterebra, a genus of botfly. Credit: CDC/ Dr. George Healy
Credit: CDC/ Dr. George Healy

A Cuterebra parasite is an opportunistic parasite found under the skin of small mammals. This parasite is the larval stage of the Cuterebra fly, who uses animal hosts to complete its life cycle. Learn more about this parasite, most commonly seen in summer and fall, in this FAQ.

9. Readers Respond: Tell us about dealing with ear mites in dogs

Has your pet been diagnosed with ear mites? Please share your story - what did you notice first, was your pet's treatment successful?

Please note: This is a space to share your story (not Q & A) with other viewers. Please see the ear mite article and ask your vet about pet-specific questions and treatments.

10. Ehrlichia - Tick-bourne Bacterial Disease

A male "brown dog tick" (Rhipicephalus sanguineus) - credit James Gathany/CDC
credit James Gathany/CDC

Ehrlichia is a type of bacteria that infect dogs and other species worldwide, causing a disease called ehrlichiosis. Ehrlichiosis has also been called tropical canine pancytopenia (and several other names). Ehrlichia is commonly transmitted by ticks.

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