When you notice worms in a dog’s stool or persistent scratching, it’s tempting to try a pantry remedy first. The problem is that “parasites” include many different organisms, and a treatment that works for one may do nothing for another. Some can affect people as well as pets.
Internal and external parasites are different problems
Roundworms, hookworms, whipworms, tapeworms and some protozoa affect the digestive tract, while fleas, ticks and certain mites affect the skin or other tissues. Heartworms live in the cardiopulmonary system and require entirely different diagnosis and care. A dog may have an intestinal parasite without visible worms; diarrhea alone does not identify the cause.
Why garlic, herbs and “natural dewormers” are risky
Garlic can damage dogs’ red blood cells, and there is no dependable evidence that household foods, oils or unapproved herbal mixtures safely clear intestinal worm infections. Using a home remedy may delay effective treatment, increase environmental contamination or expose the dog to an additional toxic ingredient. Do not use livestock dewormers or leftover prescriptions without veterinary instructions.
How the right treatment is selected
The veterinarian reviews symptoms, age, weight, travel and parasite-prevention history. They may examine a fecal sample or use other testing. One test may not detect every infection, and persistent symptoms can require additional testing. Product choice, administration schedule and rechecks depend on the organism and the animal’s condition.
The Companion Animal Parasite Council (CAPC) recommends parasite testing and year-round broad-spectrum protection tailored to the pet’s risk. Its April 2025 general guidelines recommend frequent fecal testing during the first year of life, and at least twice yearly for healthy adult animals with veterinary tailoring.
When veterinary care is urgent
Prompt examination is important if your dog has bloody diarrhea, repeated vomiting, pale gums, a swollen abdomen, weight loss, weakness or a heavy worm burden. Puppies can be especially vulnerable to dehydration and anemia from some parasites. Collapse, breathing difficulty or severe weakness require emergency care.
Practical prevention at home
- Pick up dog waste promptly in the yard and on walks.
- Wash hands after handling feces and before eating.
- Keep dogs on a veterinarian-recommended heartworm, flea, tick and intestinal parasite prevention plan.
- Prevent hunting, scavenging and access to animal feces when possible.
- Discuss boarding, travel and local parasite risks during checkups.
Do not assume a topical flea product also covers all intestinal worms or heartworms; check the exact label with your veterinarian.
What if the dog still has diarrhea after deworming?
Other infections, diet issues or inflammatory illnesses may explain the symptoms, or the original parasite may require a different approach. Call the prescribing veterinarian rather than automatically repeating treatment. Bring a fresh stool sample if requested.
Sources: CAPC: General Guidelines for Dogs and Cats; CAPC: parasite-specific guidelines.
Educational information. Testing and medication selection must be individualized by a veterinarian; no veterinary review is claimed.
This article is for general education and is not a substitute for care from your own veterinarian. Learn about The Pet Vet and our editorial policy.