Worm Symptoms in Pets

Written by: Dr. Jean Hofve, Holistic Veterinarian, DVM

The most common internal parasite problems in companion animals are intestinal worms (roundworm, tapeworm, hookworm and whipworm) and heartworm. Many dogs and cats can have a mild parasite infestation and show no symptoms. A healthy animal may fight off an infestation without their guardian ever knowing of it. Dogs and cats with stressed or weakened immune systems, however, will succumb to a more severe infestation if left unchecked.

Intestinal Worms

It seems that new pets often arrive with worms. Most puppies and kittens will have intestinal worms from birth. The worms are passed on from the mother, and the undeveloped immune systems and gastrointestinal systems of very young animals cannot keep the parasite population in check. Rescued animals should also be checked for parasite infestations as stress and crowded conditions contribute to the animal's vulnerability to parasites.

Animals can become infested by eating feces, ingesting fleas, hunting rodents, coming into contact with dead animals or eating contaminated food. Common symptoms can include:

  • Diarrhea

  • Weight loss

  • Gastrointestinal disturbances

  • Anemia

  • Scratching, particularly around the base of the tail

  • Vomiting

  • Mild to severe coughing

  • Eating a great deal without putting on weight

  • Bad breath

Puppies and kittens with roundworms may appear to have a pot belly and exhibit slow growth. They can be born with a roundworm infection or become infected from the mother's milk. The mother does not have to have an active worm infestation to pass worms to her puppies or kittens–the roundworm larvae may encyst in her system for years until the hormones of pregnancy signal the larvae to migrate and develop. Rodents are also common carriers, so if you have a hunter in the household, it is wise to regularly check for roundworm. If the roundworm infestation is severe, long, whitish worms may be seen in the stools, but they are more commonly detected through a fecal examination by a veterinarian that reveals the presence of eggs. The life cycle of these worms includes a trip through the respiratory system (as microscopic larvae), they are then swallowed and complete their development in the intestinal tract.

Hookworms are more common in dogs than cats. As with roundworms, puppies and kittens can be infested in-utero or from the mother's milk. Hookworms attach to the wall of the intestine and suck blood. If the infestation is severe, the animal will develop anemia. Older dogs with a weakened immune system are also susceptible and may show signs such as poor weight maintenance, poor stamina, progressive weakness, and possibly bloody diarrhea. It is important that older animals visit their veterinarian for regular checkups, as not all decline in activity can be written off to "old age."

Whipworms are also more common in dogs than cats. They are difficult to detect as they are seldom seen in the stool and they produce relatively few eggs, so a single fecal exam may not reveal the problem. The most common signs of whipworm are chronic weight loss and stools that seem to have a mucous covering–particularly on the last bit of stool passed. Whipworm infestation has also been known to manifest the same symptoms as Addison's Disease. If a dog shows the signs and symptoms of Addison's Disease such as a waxing and waning weakness with inability to conserve salt - ultimately resulting in dehydration, and the tests for Addison's come up negative, then de-worming for whipworm may be in order.

If you are seeing small worms in your dog or cats' stools, fur or bedding, then you are likely seeing tapeworms. Tapeworms look like flattened grains of rice, and are usually found on your companion's bedding and/or the fur around the anus, or sometimes in the stools. They often do not show up in a fecal exam by a veterinarian, so watching your pet's bedding and fur are the best ways to detect them. Tapeworms come with flea infestations, as they are carried by fleas. Before treating for tapeworm, you must first eradicate any fleas in the environment (home and yard) or your pet will likely become re-infested with tapeworm after the de-worming treatment. (See our article, The Natural Approach to Flea Control for more information on dealing with fleas). Consuming rodents with tapeworms or fleas may also cause infestation, so again if your companion likes to hunt, regularly check for tapeworm.

If you suspect your companion may have worms, it is very important to have a stool analysis performed by a veterinarian to determine the type of worm for which treatment is needed.

Prevention and Treatment

A healthy animal with a strong immune system eating a high-quality, raw food diet is may be less susceptible to worms and parasites of all kinds. Cleaning litter boxes regularly or "scooping" the yard on a regular basis is also important.

In treating puppies and kittens I generally recommend using prescription de-wormers. The newer prescription worm medications available to veterinarians are very effective and relatively safe and gentle. I do not recommend over-the-counter worm medications – many are harder on the animal's system and less effective. As worm medications only kill the worms in the animal's intestines, a fecal analysis should be done approximately 3 weeks after the initial de-worming to ensure that no migrating worms were able to re-infest the animal's intestines.

Herbal worm remedies have been used successfully for many years. They are particularly effective for less severe infestations and are safer and gentler than over-the-counter medications. There are no rigorous tests of the natural de-worming remedies available since there is no money to be made there, but these remedies have been used for many years for humans and animals.

Digestive Enzymes and Probiotics are also good companions to any de-worming program, conventional or herbal, to help support the digestive tract. Follow the de-worming process with a course of a herbal gastrointestinal supplement, like Only Natural Pet GI Health Herbal Formula or Only Natural Pet GI Support capsules, both of which support the intestinal tract and make the animal less susceptible to further infestation.


Depending on where you live, choosing a method of heartworm control may be a difficult decision. Residents of the Pacific Northwest are fortunate and do not have a heartworm problem. Those living in the Southeastern states and on the Gulf Coast, however, must deal with the issue year-round. If you live in an area where the risk of heartworm infestation is high, the decision of whether or not to use conventional heartworm medications to prevent heartworm infestation is one that should be guided by careful research and consultation with a holistic veterinarian. If it snows where you live, then year-round heartworm protection is over-kill.

Overuse of insecticides for flea and heartworm control are believed, by most holistic veterinarians, to contribute to the increasing prevalence of cancer and chronic disease in our companion animals. The long-term health of the animal needs to be weighed against the risks of chemical prevention.

Chemical heartworm preventatives work by continual administration of a low dose of insecticide to kill any developing microfilaria in the animal's bloodstream. Herbal preventatives work in a similar fashion, only using herbs instead of pesticides, and they also make the animal less appealing to mosquitoes in the first place. NEITHER method kills adult heartworms, which is why regular testing for heartworm is absolutely necessary regardless of what method you choose for prevention.

As with all herbal remedies and treatments, the healthier the animal overall, the more effective the treatment will be. Providing your companion with the best diet along with proper supplements for optimal health will go a long way to preventing disease and making them less appealing and susceptible to parasites.

Please see our article "The Truth About Heartworm in Pets" for more information.