Parasites: The Threat to Your Pet

By: Taylor Cox, Veterinary Assistant at Lebanon Small Animal Clinic

Here it is again, your pet’s annual trip to the vet. Every time you go it seems like the doctor wants to run a bunch of expensive tests and every year you wonder the same thing; are these tests really necessary? Well, one would think if the tests were not necessary they wouldn’t be run, or for that matter, they wouldn’t even exist. So they are important enough to exist but, every year? Absolutely!

What are parasites and what are common types of parasites? defines a parasite as, “an organism that lives on or in an organism of another species, known as the host, from the body of which it obtains nutriment” (“Parasite”). More simply put, a parasite is an organism that uses another organism to survive and grow without providing anything in return. While this sounds more like a mild annoyance rather than a life threatening situation, this definition leaves out some important details. Often parasites take valuable nutrients that your pet needs, leaving them malnourished. In some cases, parasites can even spread diseases that can be life threatening. The tick, for example, is known to transmit at least 7 major diseases to dogs in the United States (“Canine Tick-Borne Disease”).

What parasites should you be looking out for? The best answer is, of course, all of them. There are many parasites that can negatively impact your pet and have the potential to affect humans as well. This could be a threat to your pet, you and your family. Watching out for parasites seems like a lot of work, and it can be. Luckily, we have preventatives to help. What preventatives do your pets need? That depends on what parasites your pet can get. There are two major types of parasites, internal and external. Internal parasites include but are not limited to: heartworms, roundworms, whipworms, hookworms, tapeworms and protozoa, such as, giardia and coccidia. External parasites can include but are not limited to; fleas, ticks and mosquitos.


Of all the parasites, the most deadly is the heartworm. Heartworms are a blood-borne parasite. People

Figure 1: An example of a heart filled with heartworms (“Heartworm Disease”)

often ask if heartworms are tested for in fecal matter. Due to the nature of the heartworm and the fact that they live in the blood vessels, primarily those of the heart and lungs, they can only be tested for in the blood. Heartworms are transmitted by mosquitos, which is why heartworms are so difficult to prevent without preventative medication. Heartworms have been diagnosed in every state in the United States (“Heartworm in Dogs”). Mosquitos live almost everywhere, including inside of the house. Even though many people are very careful to keep these nuisances out, they can still sneak in. While heartworms can affect both cats and dogs, dogs are most commonly affected. Cats can be damaged by heartworms, but it is less common for them to be affected than dogs. Preventatives are always a good idea for cats and dogs as they are the best way to ensure your pet is safe. Heartworm tests are often the most expensive parasite-related test, but usually the most important. Animals with heartworms often do not show symptoms until the disease has progressed significantly. While the tests can be costly, the treatment is even more expensive, up to thousands of dollars. Not to mention, heartworms can leave lasting damage to your pet, even after they are cured. It is always best to keep up on prevention and yearly heartworm tests.

Internal Parasites

Almost all intestinal parasites can be found in fecal matter. Roundworms, whipworms, hookworms, tapeworms, giardia and coccidia are all simply tested for

Figure 2: Whipworm eggs, one of the many parasites found in dogs (“Fecal Float Parasite Pictures Gallery”)

by bringing a fecal sample in to your vet and letting them take it from there. Fecal tests take about ten minutes to run and are often inexpensive. While many of these parasites can be prevented with the same type of medication used to prevent heartworms, parasites can still pop up. Common symptoms include scooting, vomiting, diarrhea, bloody stool, a distended abdomen, weight loss, and occasional coughing (“Intestinal Parasites in Dogs”). Tapeworms are very large and can often be seen in the stool. These parasites do not always present with symptoms so it is important to have a fecal test done yearly as these parasites can have a negative impact on your pet’s health. Often these parasites are quickly and easily taken care of with a prescription for a dewormer from your veterinarian. It is important that you get the correct dewormer as certain parasites are susceptible to different classes of dewormers. Many of these parasites are communicable to humans so it is important to have them treated right away. Your veterinarian will be able to provide the best treatment for your pet.

External Parasites

Figure 3: Some tick Species contractible by pets (Ticks).

External parasites include fleas, ticks and mosquitos. As mentioned previously, mosquitos can spread heartworms and other diseases to your pet. Mosquito bites are hard to prevent but a good heartworm preventative can help save your pet from deadly heartworms. Ticks also carry a number of diseases including but not limited to Lyme disease, two strains of Canine Ehrlichiosis and Canine Anaplasmosis, all of which can be tested for in combination with a heartworm test (“Canine Tick-Borne Disease”). It is best to check for ticks frequently even if you use a preventative. Always check your pet after being in wooded areas or areas with tall grass as ticks like to hide there. Ticks can even be seen during colder months like January and February. Deer ticks, which carry Lyme disease, can be out in temperatures as low as 30 degrees Fahrenheit. Fleas are more of a nuisance than anything but some animals can have an allergic reaction or hypersensitivity to flea bites on top of the itchiness they already cause. The easiest way to prevent these parasites is to use an oral or topical preventative. There is also a vaccination available for Lyme disease if there are a high number of ticks in your area. Some topical preventatives can be purchased from pet stores but make sure that they are good quality and will work well in your area. Often veterinary clinics are the best place to purchase these preventatives and will carry the most effective products. It is important to note that with oral preventatives these parasites often need to bite your pet to die this way the parasite is not attached long enough to transmit diseases. If you use a preventative and you see fleas or ticks on your pet it is likely dead or dying but it is always better to be safe than sorry. If you have any concerns call your veterinarian.

*It is important to use all preventative and treatment products as directed by your veterinarian as incorrect dosing can potentially harm your pet.

*For further questions about Heartworms and other parasites, or if you are concerned that your pet might have a parasite, you can call us or schedule an appointment.

*If you have specific heartworm questions you can also visit American Heartworm Society for more information.


“Canine Tick-Borne Disease.” AKC Canine Health Foundation. N.p., n.d. Web. 19 July 2017.

“Fecal Float Parasite Pictures Gallery.” Pet-Informed – complete, practical, free veterinary advice for pet owners. N.p., n.d. Web. 19 July 2017.

“Heartworm Disease.” N.p., n.d. Web. 19 July 2017.

“Heartworm in Dogs.” American Heartworm Society – Heartworm in Dogs. N.p., n.d. Web. 19 July 2017.

“Intestinal Parasites in Dogs.” Pet Health Network. N.p., n.d. Web. 19 July 2017.

“Parasite.”, n.d. Web. 19 July 2017.

Ticks. N.p., n.d. Web. 19 July 2017.