Intestinal parasites are among the most common health concerns affecting both dogs and cats. Many pets can carry parasites without obvious symptoms, which is why routine screening and prevention are essential parts of veterinary care. More than just being gross, some of these parasites can also pose a risk to human health, making early detection and prevention even more important.
Below is an overview of several common intestinal parasites, including how they are transmitted, diagnosed, treated, and prevented.
Giardia
What it is:
Giardia is a microscopic protozoan parasite that infects the small intestine. It is not a worm but a single-celled organism. Some strains of Giardia are zoonotic, meaning they can be transmitted between animals and humans.
Transmission:
Pets become infected by ingesting contaminated water, soil, or feces. This is especially common in areas with standing water or high animal traffic, such as dog parks, kennels, or shelters. Giardia can form cysts that can survive for months in the environment.
Diagnostics:
Giardia is typically diagnosed through fecal testing, including antigen tests or microscopic examination. Because shedding can be intermittent, multiple samples may be recommended.
Treatment:
Treatment usually involves prescription medications such as fenbendazole and/or metronidazole. Bathing the pet during treatment is often recommended to reduce reinfection. Monthly parasite preventions do not treat or prevent Giardia.
Prevention:
- Avoid allowing pets to drink from puddles or standing water
- Promptly clean up feces
- Maintain good hygiene in multi-pet environments
- Routine fecal screening
Roundworms
What they are:
Roundworms are long, spaghetti-like intestinal worms. While they can be found in animals of any age, they are commonly found in puppies and kittens. Some species of roundworms are zoonotic.
Transmission:
- Passed from mother to offspring (through the placenta or milk)
- Ingestion of contaminated soil or feces
Diagnostics:
Roundworms are diagnosed through fecal examination, where eggs are identified under a microscope.
Treatment:
Deworming medications are highly effective and are often administered in a series, especially in young animals.
Prevention:
- Routine deworming protocols for puppies and kittens
- Monthly parasite preventatives
- Proper disposal of feces
Hookworms
What they are:
Hookworms are small, thin worms that attach to the intestinal lining and feed on blood. Humans can also become infected with hookworms.
Transmission:
- Larvae in contaminated soil can penetrate the skin
- Ingestion of contaminated material
- Passed from mother to offspring
Diagnostics:
Fecal examination is used to identify hookworm eggs.
Treatment:
Treatment involves deworming medications and, in severe cases, supportive care for anemia.
Prevention:
- Monthly parasite prevention
- Keeping environments clean and dry
- Routine fecal testing
- Avoiding areas with heavy fecal contamination
Whipworms
What they are:
Whipworms are parasites that reside in the large intestine and can cause chronic irritation.
Transmission:
Pets become infected by ingesting whipworm eggs from contaminated soil or environments. Whipworm eggs are particularly difficult to eliminate in the environment and can remain infectious for years.
Diagnostics:
Whipworms can be more difficult to detect, as eggs are shed intermittently. Multiple fecal tests may be needed.
Treatment:
Treatment requires specific deworming medications, often given over several months to fully eliminate the infection. Dogs that frequent a contaminated environment may become reinfected after treatment. Once an area contains whipworm eggs, environmental control is challenging and can require the removal of several inches of topsoil to eliminate them.
Prevention:
- Regular fecal screening
- Monthly preventatives that cover whipworms
- Environmental hygiene (picking up feces promptly), especially in yards
Coccidia
What it is:
Coccidia are microscopic, single-celled protozoan parasites that live in the intestinal lining. They are most commonly seen in puppies and kittens, but pets of any age can become infected, especially in high-stress or high-density environments. Coccidia can cause diarrhea ranging from mild to severe, particularly in young or immunocompromised pets. Early detection and treatment help prevent complications and reduce environmental contamination.
Transmission:
- Pets become infected by ingesting infective oocysts (eggs) from contaminated environments. This can occur through:
- Contact with contaminated feces
- Grooming contaminated fur or paws
- Exposure to crowded or unsanitary conditions (shelters, breeding facilities, daycare)
- Ingestion of infected prey
Unlike some other parasites, coccidia are highly species-specific, meaning dogs and cats typically do not transmit the same types to each other.
Diagnostics:
Coccidia are diagnosed through fecal examination, where oocysts (eggs) are identified under a microscope. Because shedding can vary, repeat testing may occasionally be recommended.
Treatment:
Treatment typically involves prescription medications such as ponazuril, which help control and eliminate the organism. Supportive care may also be needed in pets experiencing diarrhea or dehydration. There are no monthly preventatives at this time for coccidia. Coccidia is resistant to most disinfectants and it is nearly impossible to eliminate from grass and soil.
Prevention:
- Prompt and thorough fecal cleanup
- Regular disinfection of living areas (specific products or steam cleaning may be recommended)
- Routine fecal screening, especially in young pets
- Minimizing stress and overcrowding
- Maintaining good hygiene, including washing hands after handling pets or cleaning litter boxes
Tapeworms
What they are:
Tapeworms are flat, segmented worms that live in the intestines. Dried segments may appear like small grains of rice around the pet’s rear or in bedding. Humans can become infected with some species of tapeworms. Tapeworms are commonly seen in pets with flea infestation.
Transmission:
- Most commonly transmitted through ingestion of infected fleas
- Consumption of infected prey
Diagnostics:
Tapeworms are often identified by visible segments rather than fecal testing, although eggs may sometimes be detected.
Treatment:
A specific deworming medication (such as praziquantel) is required to eliminate tapeworms. Many monthly preventatives do not treat or prevent tapeworms, but those that control fleas will reduce a common route of transmission.
Prevention:
- Consistent flea control
- Preventing hunting and ingestion of prey
- Maintaining a clean living environment
The Importance of Prevention
Many intestinal parasites can be effectively controlled with routine veterinary care. Regular fecal testing, year-round parasite prevention, and good hygiene practices are the cornerstones of keeping your pet—and your family—safe. Pets that have a higher risk lifestyle, such as outdoor cats or dogs that frequent dog parks, may need more frequent testing for parasites.
Even pets that live primarily indoors are at risk, as parasites can be brought into the home on shoes, through other animals, or via fleas.
Signs of intestinal parasites may include:
- Diarrhea or soft stool
- Abdominal pain
- Vomiting
- Weight loss
- Pot-bellied appearance (especially in young pets)
- Scooting or visible worms
However, many pets show no symptoms at all. That’s why routine testing is so important.
If you have questions about parasite prevention or would like to schedule a screening, Friendship Animal Hospital is here to help guide you in choosing the best plan for your pet.
Protecting your pet from parasites is a simple step that makes a lasting impact on their overall health and well-being.
