The Guide to Pet Parasites


Spring is here, which means more puddles and mud to navigate on daily walks and at the dog park. In addition to being messy, this time of year can also be dangerous for your pet’s health.

Parasites are rampant in springtime, and are easily transmittable through feces and standing water. Be sure to wash and dry your pet’s fur and paw pads carefully when re-entering your home. Watching your pet carefully, keeping him up-to-date on preventatives, and knowing where he’s been are all extremely important in preventing your pet from getting infected this season.

We always advocate that the more you know, the better you can protect your pet, which is why we’ve put together this introductory guide to the parasites that threaten your pet.


Roundworms tend to be the most common of the parasitic worms, and they live and reproduce in the small intestine. For most adult animals, roundworms are low risk and don’t cause serious health problems. Many pets don’t show physical signs of infection, and roundworms may only be discovered by seeing them in feces or vomit. They are white or light brown in color, and are one to seven inches long. In some cases, especially with young puppies and kittens, pets may experience diarrhea, vomiting, weight loss, dull hair, and a bloated appearance.

Roundworms lay microscopic eggs that can be easily transmitted in environments where animals play, defecate, or share food/water. Pets can also get roundworms by ingesting infected animals such as birds or rodents.


Tapeworms are long, flat worms that attach themselves to the walls of an animal’s intestines. There are several types of hosts that tapeworms prefer, including fleas, mice, rats, squirrels, rabbits, or larger animals such as deer or sheep. If your pet ingests any of these she is at risk, and a fecal sample is recommended, since tapeworms can be hard to detect with the naked eye.

Animals with tapeworms rarely “look” sick with physical symptoms, however, as time passes you may notice a dull coat, loss of appetite, or weight loss. These parasites are generally diagnosed when a person notices segments—tiny white worms resembling grains of rice or seeds—near a pet’s anus, in their feces, or where your companion animal lives and sleeps.


Hookworms get their name from the tiny “hook” that attaches to an animal’s intestinal lining, feeding off of your pet’s blood. Hookworms are easily transmittable through soil, feces, and contact via skin or paw pads. Many adult animals develop an immunity to hookworms as they grow, however for puppies and kittens, hookworms can be dangerous. If the parasites go undetected for an extended period of time, animals may develop anemia due to the loss in blood.

As with most parasites, definitive symptoms can be hard to pinpoint, but animals may have diarrhea and vomiting, or signs of anemia which include lethargy, weakness, or pale gums.


The good news is that heart worms are nearly 100 percent preventable. The bad news is that if an animal does get them, they can be extremely devastating and even fatal.

Heartworms are transmitted by mosquitoes. Mature parasites can measure more than one foot and live in the heart and large blood vessels of the lungs. Their location means other organs, including kidneys and the liver, can be affected, so symptoms can vary. Pets may be asymptomatic early on, but as the disease progresses animals may be lethargic, have shortness of breath, or start coughing on a regular basis. Heartworms are a serious issue, and if left untreated, the infection can be fatal. It is important to discuss options with your vet, and if you choose not to administer heartworm preventatives on a consistent basis, you must do


Whipworms reside in the cecum, where the small and large intestines meet, attaching to mucus membranes and feeding off of their host’s blood. They are two to three inches long, and tapered at one end—like a whip. As with other common parasites, they are transmitted via the presence of feces in soil or water. Their eggs easily survive in the environment and can be difficult to get rid of, so reinfection after initial treatment is common. Most infected pets display symptoms such as diarrhea, vomiting, and weight loss. It is important to do a fecal test if you suspect your pet may have this parasite, since severe whipworm infection may lead to serious disease or even death.


Giardia is a single-celled parasite that attaches to an animal’s intestine—not a worm, virus, or bacteria. Any animal can be affected, but it is seen most frequently in puppies and kittens. Giardia is transmitted in water, soil, and other substances that may contain feces. Symptoms can be tricky to spot, but watch out for foul-smelling, soft-to-watery stool that may be greenish in color and contains mucus or blood. Routine fecal tests are important since living with giardiasis for a long time can cause weight loss, poor overall health, and even death.

Early parasite prevention:

While there is definitely controversy regarding the over-vaccination of our pets, it is extremely important that young animals follow their vet’s guidelines for vaccines. Being current and up-to-date on preventative vaccines can mean the difference between life or death in some cases, especially for puppies, kittens, or any pet with a compromised immune system.

Holistic ways to keep your pet healthy:

Healthy immune systems are related to the health of the gut. Fermented foods have probiotic properties and may help in preventing and even eliminating worms. Some suggestions include fermented veggies (such as sauerkraut or kimchi) or non-dairy kefir (between 1-3 tbsp/day depending on size). You can also add other raw, fresh vegetables such as carrot, pumpkin, watercress, greens, papaya, squash, or fennel. Introducing parsley or chamomile, dried coconut, or apple cider vinegar can also be effective. Always check with your veterinarian before adding any new foods to your pets’ diet.

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