Roundworms in Dogs
Roundworms in dogs are probably the most commonly found intestinal parasite, other than tapeworms. Toxocara canis, also called Ascarids, are a species of roundworm found in dogs and cats, with other mammals acting as carriers of the parasite eggs. These worms are not usually seen since adult roundworms live in a dog’s intestines, so it can come as a surprise to an owner to learn their dog has a roundworm infection.
There are few different ways that dogs can contract roundworms. To begin with, it can be assumed that most puppies will have roundworms when they are born, contracted from the mother dog. Though it might seem impossible for a well cared for dog to give roundworms to her puppies, it is the way most puppies end up infested with them. Parasite larvae that have been present from the time the mother was a puppy herself will encyst in muscle tissue, where they will hibernate indefinitely, waiting for a signal to emerge and complete their lifecycle.
When a pregnant dog’s hormones ‘wake up’ the encysted larvae, they emerge from body tissue and make their way to the placenta. From there, roundworm larvae then reach the puppies themselves, where they will complete their growth cycle to begin laying their own eggs around the time the puppies are born. Larvae will also enter the mammary glands, infecting puppies through their mother’s milk. Once puppies have an active infestation of roundworms, the cycle begins all over again with larvae embedding into muscle tissue, ready to infect the next generation of puppies to continue the species.
Deworming female dogs just before becoming pregnant can sometimes help kill off some of the larvae that will emerge once she does, but there will always be some that survive to infect the puppies. It is recommended that all puppies be dewormed beginning at two weeks of age, and then every two weeks thereafter, until at least eight weeks of age. By deworming every two weeks, this will greatly lessen the numbers of roundworm larvae that actually make it to embed into the muscle tissue, and will prevent any larvae from surviving to become adults. It does take a few rounds of deworming to clear the infections, however, so the bi-weekly deworming is important. Worming just once is not enough.
Other ways roundworms in dogs can occur are through puppies or older dogs ingesting parasite eggs. That can happen if a dog does eats the stools of another animal that is infected with roundworms, the eggs releasing and quickly maturing once they reach the intestinal tract. Dogs that hunt and eat what they catch, such as mice, birds, rabbits or other small mammals, will frequently develop a roundworm infestation from encysted larvae in the tissue of the eaten animal.
Roundworms in dogs are detected through routine fecal tests run by a veterinarian. For this reason, it is very important to have a dog’s stool checked for parasites at least once every year, at least twice in the first year of life. Samples are tested in such a way that microscopic parasite eggs can be isolated and identified at a laboratory, at which point the veterinarian will know to use the appropriate deworming medication to remove them.
Occasionally, if there is a very heavy parasite load, roundworms may be seen in a dog’s stools. A heavily infected dog may also vomit adult roundworms, though that is not as common. Roundworms look like a piece of spaghetti in the stool or vomit, making them easy to identify when adults. However, if mature worms are found in the stool, or are vomited up, this indicates that the parasite load in the intestines is significant. The dog should be dewormed as soon as possible, and the deworming should be repeated in two weeks.
In most instances, dogs don’t usually suffer negatively from having roundworms, but it is always possible for the dog to show signs of parasite infection if there are many. A dull coat and weight loss are the main indicators that there could be a parasite problem, since the worms are consuming much of the nutrition in the intestines before they can be absorbed by the dog. It should be noted, too, that a heavy load of roundworms in young puppies that is left untreated can cause a pot-bellied look, as well as a cough, if the worms should move into the lungs.
Infections of roundworms in dogs are generally easy to treat. Dosing the dog with pyrantel pamoate liquid, or another broad-spectrum dewormer, usually takes care of roundworms in two doses. Additionally, most monthly heartworm preventatives contain medication that will break the roundworm lifecycle, aiding in preventing full blown infections of roundworms in dogs. Also, as an additional preventive measure, dogs that frequently have parasites, or are at risk of getting parasites, should be regularly dewormed every three to six months to be safe, especially since roundworms are one species of parasite that can be transmitted to humans, most notably children.