Internal Parasites

Internal Parasites are worms or other pets that live inside your pet, usually in the intestines where they get their energy from the food that your pet eats, or from sucking blood from the gut wall. There are many different, very effective dewormers that you can get from your veterinarian. These come in pill form or topical preparations that you put on your pet’s skin. Here are some internal parasites you should be aware of to keep you and your pet safe, happy, and healthy!

Hookworms are small worms that live in a dog or cat’s intestines. The pet contracts hookworm from eating an infected small mammal (like a rat), through the milk of a mother dog, or from accidentally eating the tiny larvae in the environment (usually from eating grass). Signs of hookworm include blood in the feces, and low red blood cells (anemia).

Finding hookworm in a pet is done by collecting some of your pet’s feces, mixing them with a special solution and looking at the result under the microscope. This procedure is called a fecal floatation. The eggs of a hookworm are easily recognized by both veterinarians and veterinary technicians. Hookworm can be transmitted to transmit to humans through the environment when bare skin (usually hands or feet) touch ground infected with the larvae. If you have a dog or an outdoor cat, wear shoes outside – or better yet, deworm your pet!

Roundworms also infect both cats and dogs, and this worm is fairly common almost everywhere. They are long, large white worms that look like spaghetti (sorry pasta lovers!). An infected dog or cat passes the inactive eggs in their feces. Once the eggs hit the environment, they become active and infective, and dogs and cats can get infected (or reinfected) by eating those active eggs. If this happens, the egg will hatch into a larva that travels around the pet’s body, including the liver and lungs before settling in the intestines.

Young animals infected with roundworm show a typical pot belly and diarrhea. Adult animals often pass worms in the feces or vomit them up – this is sometimes the only way that people know their pet has roundworm. Roundworm can infect people, but the larvae get confused and migrate to the nervous system, eyes, or liver instead of the intestines. To make sure your pet doesn’t carry this parasite, deworm monthly, or have a fecal float performed regularly if you don’t want to deworm year-round.

Tapeworms are long segmented worms that pass in feces as small flat pieces. The tapeworm larvae look like grains of rice and are often seen hanging out by the back end of your pet. Pets (both cats and dogs) get tapeworm from eating fleas or eating mice. Because often the only sign of tapeworm is seeing the little larvae at your pet’s bottom, and tapeworm eggs are hard to find under a microscope, deworming any animal with fleas or access to small mammals to eat is an excellent idea. Treating your pet for fleas regularly will also help prevent tapeworms. Some types of tapeworm can be passed to humans so was your hands if you see grains of rice on your pet!

Different medications are needed to treat tapeworm than hookworm and roundworm, so make sure to talk to your veterinarian if you suspect that your pet has a tapeworm.

Heartworm is a worm that lives in the blood vessels of the heart. With this worm, prevention is KEY! There are many effective heartworm medications and all dogs and cats, especially those travelling to other provinces or the USA should be on one of those dewormers. Heartworm is spread by mosquitoes – they bite an infected dog then spread the infection when they bite another dog. This means that mosquito season is heartworm season!

In dogs, heartworms clog up the blood vessel by simply taking up space. Because the heart has to work harder to pump blood through the clogged vessel, a cough, lethargy and exercise intolerance can occur. In severe cases, with lots of worms, shock, heart failure, and pale gums can occur. Treatment is tricky and controversial, but all forms of treatment involve at least 120 days of strict cage rest while the worms die off. Prevention is better than treatment!!

Many monthly oral and topical preparations are available for dogs – these medications often include an ingredient that kills roundworm and sometimes tapeworm as well. As for cats, mosquitos spread the worms from infected dogs to uninfected cats. Usually, only a small number of worms survive in cats, but they can still block small blood vessels and produce an immune response. Most cats present with increased breathing rate and trouble breathing. No treatment is available for cats because they are highly allergic to dead or dying worms. Like with dogs, many topical and oral products are available for prevention of heartworm in cats.

As you can tell, while treatment of most of the above internal parasites is possible, prevention is much easier, safer and healthier for both you and your pet. Talk to your veterinary care team about parasite prevention for your pet!

Written by Dr. Teigen Bond DVM