A dog can get worms anywhere. Intestinal worms are acquired through contact with infected grass, dirt or feces. Dogs get heartworms through a bite from an infected mosquito. According to Healthy Happy Dogs, you may never even know your dog has worms. Small infestations may cause no symptoms, but large worm infestations can be a threat to your dog's health. There are many chemical de-worming medications available through your veterinarian or from your local pet store; however, Precious Pets reports that those chemicals are toxic to both the worms and the dog, they cause weakness, vomiting, diarrhea and convulsions in some dogs. There are much safer alternatives.
Ground pumpkin seeds will expel intestinal worms from both animals and humans. Pumpkin seeds are recommended by research chemist Mark Pedersen in his book "Nutritional Herbology: A Reference Guide to Herbs" for the elimination worms and parasites from the digestive tract. Blue Star Product Pet Boutique also recommends pumpkin seeds for worming dogs.
Black walnut is an astringent and contains a substance called juglone. According to Rosemary Gladstar, in her book "Herbal Remedies for Vibrant Health," juglone is responsible for the antifungal and anti-parasitic properties of black walnut. Precious Pets recommends black walnut for dogs.
Probiotics are the name given to beneficial intestinal bacteria. In an healthy digestive tract, probiotics are plentiful. Worms cannot thrive in an environment that contains large amounts of these healthful bacteria. Giving your dog probiotics will both flush out existing parasites and prevent new ones from taking up residence in your dog. Your vet may be able to recommend a probiotics formula for your dog.
If you're looking for a commercial product to rid your dog of worms, there are several natural de-wormers on the market. Parasite Doctor contains wormwood, cloves, neem, herb of grace and rice powder. It is available through Pet Alive.
Artemisia Combo is an commercial product for the natural prevention and removal of heartworms. This preparation contains a proprietary blend of ginger root, elecampane root, mugwort, clove flower buds, garlic, turmeric, olive leaf, wormwood and spearmint. This preparation is recommended by Precious Pets as part of the NSP Natural Heartworm Prevention Program.