Pets are extraordinary creatures with complex inner lives that we can only admire and hypothesize about. Unfortunately, an unpleasant but natural part of this inner life may include internal and external parasites.

Gross, right? But before you shun your Shih-tzu or dismiss your Devon Rex, know that parasites—and most parasitic diseases—are easily diagnosed and treated. Most importantly, they are preventable. So go ahead and snuggle your schnoodle—but first check out this Village Veterinary Hospital guide to parasitic diseases in pets.

Microscopic most wanted—common pet parasites

Pet parasites come in various shapes and sizes, but don’t let their diminutive stature fool you—these insects, worms, and protozoans can inflict large-scale damage. The most common dogs and cat parasites include:

  • Heartworms
  • Toxoplasma
  • Gastrointestinal (GI) parasites:
  • Roundworms
  • Hookworms
  • Whipworms
  • Tapeworms
  • Giardia
  • External (i.e., ecto-) parasites:
    • Ticks  — Tick-transmitted diseases including Lyme disease, anaplasmosis, ehrlichiosis, Rocky Mountain spotted fever, and tick paralysis.
    • Fleas — Infected fleas can transmit tapeworms, various blood parasites, and  Yersinia pestis (i.e., the bacteria that causes plague).

Sick as a dog—how parasites affect pet health

Let’s face it—all parasites are gross and unwanted, but they vary in how they affect your pet. Young, elderly, and immunocompromised pets are always at the highest risk for experiencing severe parasitic illness. Healthy adult pets may live asymptomatically with some parasite types (e.g., GI parasites). However, all pets are equally vulnerable to dangerous parasites, including heartworms, tick-borne diseases, and blood parasites.

Depending on your pet’s health and age, and the parasite type, parasitic disease signs can range from mild to more extensive, and may include:

  • Vomiting
  • Diarrhea
  • Dehydration
  • Anemia
  • Fever
  • Malnutrition-induced weight loss
  • Skin lesions
  • Neurologic signs
  • Paralysis
  • Heart failure
  • Respiratory disease

Infected pets can also transmit parasitic diseases to other dogs and cats and, in some cases, people, so treating all parasitic infections—whether your pet is visibly sick or not—and keeping all pets on a year-round parasite prevention protocol is essential.

Share not—parasitic diseases you can get from your pet

Zoonotic parasitic diseases are those that can be transmitted from animals to humans, most often through direct exposure to infected waste, bodily fluids, or contaminated soil. As with pets, young, old, pregnant, and immunocompromised humans are at the highest risk for parasitic infection. Zoonotic parasites include:

  • Hookworms
  • Roundworms
  • Tapeworms
  • Toxoplasma
  • Fleas and ticks

If your pet is diagnosed with a zoonotic parasite, at-risk family members should speak with their primary care provider to determine if they should take additional precautions.

Where did you get that?—Parasite disease transmission routes in pets

You may be shocked to discover that your pet has a parasitic infection or disease. Naturally, you’ll want to know where and how your trusted companion became host to a nasty bug or worm. Fortunately, parasitic disease transmission is quite predictable and includes:

  • Fecal-oral route — Pets infected with GI parasites shed infective eggs in their stool. Other pets or people become infected by close contact with the contaminated waste (e.g., after disposing of pet waste, you touch your face, or you eat before washing your hands) or the surrounding soil.
  • Transplacental or transmammary — A pregnant dog or cat passes roundworms to their offspring in utero or through their milk. 
  • Bite wounds — Fleas and ticks transmit various parasitic diseases by injecting pathogens through their saliva, and mosquitoes transmit heartworm disease the same way. External parasites are obtained in the environment, either outdoors, or—in the case of fleas—close contact with infested pets or wildlife.
  • Transcutaneous — Juvenile hookworms can be transmitted through the skin, in a process known as visceral larval migrans, which is commonly seen in people or children who walk bare-footed over infected soil or play in a contaminated sandbox.

Flea bomb, anyone?—Parasitic disease treatment for pets

If your pet is diagnosed with a parasitic disease, your Village Veterinary Hospital veterinarian will provide a treatment plan. With the exception of heartworm disease—which requires specific testing, monitoring, and restrictions—most parasitic disease treatment protocols include:

  • Anti-parasitic or antibiotic medications — Dewormers and other medicines can eliminate internal parasites or resolve bacterial infections.
  • Repeat testing — To ensure efficacy, you must recheck your pet’s stool sample or blood at specific intervals. 
  • Strict hygiene and waste disposal protocols — Promptly remove pet waste, routinely disinfect litter boxes and other pet equipment, and perform thorough hand washing after any pet interactions.
  • Environmental control — Make your pet’s area less parasite-friendly by routinely vacuuming and laundering indoor surfaces, removing wildlife feeders, picking up pet waste, cutting tall grass, pulling weeds, and eliminating standing water.

Parasite non grata—protecting your pet from parasitic disease

A close-up of a Rottweiler being fed a treat by a veterinarian's hand. The gentle dog carefully takes the treat with its mouth, showcasing trust and care. The blurred background highlights this special bond.

Like it or not, parasites are part of the natural world. Fortunately, with routine wellness care and a veterinary-recommended parasite prevention plan, you can make pest threats a thing of the past. Village Veterinary Hospital encourages all pet owners to adopt a comprehensive parasite prevention plan that includes:

  • Year-round preventive use — Ensure your pet stays current on flea, tick, and heartworm medications—many contain a broad-spectrum dewormer to protect against GI parasites.
  • Annual wellness exam — Healthy pets are more resilient against parasitic disease, so stay up to date with preventive care.
  • Yearly screening tests — Annual heartworm and tick-borne disease tests and intestinal parasite screenings (i.e., fecals) ensure your pet’s prevention is working appropriately.
  • Proper pet hygiene and husbandry — Keeping your pet and their environment clean and tidy reduces exposure risks. Regular grooming or frequent “tick checks” can help you identify and safely remove external parasites before they bite.

Perhaps the only thing that makes us squirm more than parasites is the thought of our dog or cat plagued by preventable disease. If your pet isn’t up-to-date on parasite prevention or testing, contact Village Veterinary Hospital to schedule an appointment.