Internal Parasites of Dogs and Cats

February 2012, Dr. Bridget Overbey, DVM

Internal parasites as opposed to external parasites, such as fleas and ticks, can often go unrecognized by pet owners. While it can be difficult to identify if your pet has internal parasites, it is very important to treat infected animals as this can lead to health problems for them and your family. In this article we will have a brief discussion on the major internal parasites of dogs and cats, signs your pet could be infected, and the available treatments.

Roundworms
Roundworm is a generic term for several species of worms that can affect dogs and cats. Roundworms are very common, especially in puppies and kittens. Most puppies are born with roundworms since they can be passed from their mother. Kittens while not born with roundworms like puppies but can be infected by their mothers during nursing. Signs of roundworm infection include a potbelly, rough hair coat, diarrhea, vomiting up of worms, anemia, and any indication that your puppy or kitten is not thriving. It is very important to treat your dogs and cats for roundworms, as some species of worm can also infect humans. Children are the most prone to infection as they can inadvertently consume worms eggs while playing outside (via eating dirt). Since humans are not the correct host for these worms they get lost and migrate through the body, which can lead to blindness.

Hookworms
Hookworms are similar to roundworms in many respects. There are multiple species of hookworms, they can infect dogs and cats, and some species can be passed down through birth and nursing. Signs of hookworm infection are also similar to roundworm infection but can be more severe in some cases leading to a fatal anemia.

Whipworms
Whipworms are more common in older dogs and only rarely infect cats. Like the previously discussed parasites, they can cause diarrhea, constipation, unkempt appearance, and weight loss.

Tapeworms
Tapeworms can occur in both dogs and cats and are commonly acquired after they have been infected with fleas. If a pet eats a flea infected with a tapeworm they can develop an adult worm. Pets can also get tapeworms if they are outdoor hunters, i.e. eating mice or rabbits. Owners may be able to identify infected pets by finding tapeworm segments (which look similar to rice grains) in the pets’ feces or attached to the hair around the anus.

Giardia
Unlike the parasites discussed above giardia is not a worm but a protozoal organism (a single celled organism) that can cause similar symptoms. It can infect both dogs and cats, and is transmitted through contaminated water. Signs of Giardia include diarrhea and weight loss with a normal appetite.

All of these parasites can be diagnosed by testing a fecal sample from your pet. If an infection is diagnosed or suspected they are typically treated with a combination of oral medications. Yearly fecal tests and deworming is recommended for all dogs and cats. Please speak to your veterinarian about the many options for keeping your pet parasite free.

Dr. Bridget Overbey, DVM