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Roundworms: What Are They and Why They Are a Winter Risk For Your Dog

By December 16, 2020 Uncategorized

Roundworms are the most common intestinal parasite impacting companion dogs across the country, even dogs who are well cared for and receive regular veterinary care.

They live in a dog’s intestines and feed on the intestinal contents, are light brown or white and several inches long, and resemble spaghetti when in the dog’s intestines. Dogs with roundworms may show small bits of visible evidence of the worms in their poop or vomit.

Unfortunately, roundworms are incredibly common and are spread through dogs (and other animals) shedding the eggs through their feces. Other dogs then become infected by accidentally ingesting roundworm eggs while outside playing. Dogs of any age from newborn puppies to adults can be impacted by roundworms. 

Why roundworms are the risk in the winter

Dr. Craig Prior, BVSC, CVJ, the former president of the CAPC says that the council’s work on the mapping of roundworm is beginning to show a seasonal prevalence of roundworm. Unlike many other parasites, roundworms are not susceptible to temperature changes, because as Dr. Prior explains “roundworm eggs have a strong protective layer, they are not sensitive to extreme temperatures and can survive in the environment for months — and even years.”

This means our dogs can be susceptible to infection from roundworms year-round, and the risk does not decrease in winter months regardless of where in the country you live.

Curious about roundworm risks in your local area? CAPC parasite prevalence maps give a roundworm prevalence breakdown for every province in Canada (

How to prevent roundworms in dogs

The most important thing you can do to protect your dog from roundworm is to keep areas where your dog spends time clean and to not allow your dog to spend time in parks or areas where dog feces are allowed to buildup. Dog waste is one of the primary causes of roundworm spread. All dog parents can help prevent the spread of roundworms by immediately picking up feces when walking our dogs in public areas and regularly from our backyards.

Unfortunately, CAPC has discovered that 27% of fecal samples collected in dog parks from across the country showed that roundworm was present. In response to the prevalence of roundworm, CAPC recommends that puppies be tested for roundworm at least four times in their first year of life. CAPC also recommends that adult dogs be tested at least twice a year and that dogs receive monthly broad-spectrum parasite preventative medication year-round.

What are the symptoms of roundworm in dogs?

Symptoms of roundworm infection in dogs include weight loss, diarrhea, dull coat, vomiting as well as a bloated/pot-bellied abdomens. If left untreated a roundworm infection can be fatal to dogs. Although at times you can see worms in your dog’s vomit or feces, the key way that you can check if your dog has roundworm is through a veterinary examination. “Your veterinarian can check your dog’s stool, be able to treat them if they are positive, and then put them on a preventive,” said  Dr. Prior.

Roundworms are also a risk for humans.

Not only are roundworms dangerous for our dogs, they can also pose significant health risks for people. Humans generally become infected with roundworms from handling and then accidentally ingesting dirt that contains roundworm larva. Children are particularly at risk because they are likely to spend time playing outside and dirty soil is more likely to come in contact with their mouths. Another reason to wash those hands. Symptoms of roundworm infection in humans include fever, cough, abdominal pain, and in severe cases, roundworms can lead to respiratory failure or blindness.

How Do Indoor Cats Get Roundworm?

You do everything you can to protect your beloved feline — after all, she is a part of your family. Even though you keep her inside and get her regular checkups, she may still wind up with a roundworm infestation. If Trixy is showing certain symptoms, she’ll have to see the vet.

What Is A Roundworm?

Of all the various types of worms felines can get, roundworms are the most common variety, according to the ASPCA. They are round, off-white in color, anywhere from 3 to 6 inches long and create a nest inside your kitty’s intestinal tract. If there are several present, they can get into her bloodstream and move up into the liver and lungs, leading to severe problems.

How They Get It

There are a number of ways your indoor feline companion can get roundworms. Kittens can become infected with the parasite from their mother’s milk. If you recently adopted your kitten, it’s possible she had roundworms before you brought her home. She can also get roundworms by feasting on an infected rodent. Even if she never wanders outside, if she has access to your unfinished basement or cellar, she can still come into contact with a rodent. Some type of bugs and flies also carry roundworm larvae (Adult house flies (Musca domestica) carry and transmit more than 100 human and animal diseases, including salmonellosis, anthrax, typhoid fever, tuberculosis, cholera and diarrhea as well as parasites such as pinworms, roundworms, hookworms and tapeworms.). When little Trixy swallows a larvae-carrying cockroach, for example, the eggs could hatch in her system, leading to an infestation.


Once the roundworms start thriving in your precious pal’s belly, you’ll see signs of gastrointestinal distress. She’ll have diarrhea and blood in her stool, and she may drop weight suddenly. Constipation and vomiting may also occur. Watch for worm fragments in her stool or worms lurking out of her rear end. Roundworms look similar to cooked spaghetti noodles. If the infestation spreads up into her respiratory tract, she’ll cough and have problems breathing as well.

Diagnosis And Treatment

Before taking Trixy to the vet, gather a fresh stool sample in a plastic bag and take it to the office with you. Your veterinarian will need to check her stool for larvae and worms to determine exactly which type of worm is in her gut. Medicine for each type of worm varies, so proper diagnosis is important. When roundworms are apparent, he’ll give her an oral deworming medication called an anthelmintic, Animal Planet reports. This medication forces the roundworms to come out when she has bowel movements. Depending on how badly she is infected, you may need to administer the deworming medication one or two more times, with several weeks in between doses.


Keep your purring friend away from areas that may attract rodents, like the basement or screened-in back porch. If you notice bugs in your home, get rid of them before Trixy has a chance to dine on the critters. Your veterinarian can prescribe monthly flea and heartworm medications that help fight her chances of getting stuck with a roundworm infestation.

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