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

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. Companion Animal Parasite Council (CAPC) which tracks infection rates nationally noted that dog fecal samples across the United States showed that  30 percent of dogs younger than 6 months shed roundworm eggs making this an issue impacting dogs of all ages from puppies to adults. In addition, CAPC studies have found that positive cases of roundworm infection have been detected in dogs in all 50 states across the country.

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. The CAPC releases a monthly update of US cities that have the highest positive percentage increase of roundworms. Bookmark the monthly study (here) to check for updates.

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 county in the United States.

roundworms in dogs

A small pack of dogs play at a public, off-leash dog park. Photo: Darwin Brandis/ Getty Images

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.

Related: Potty Training Dogs — 9 Tips for Success

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.

Featured photo: chabybucko/Getty Images

Read Next: Keep Your Dog Safe From These 10 Outdoor Dangers


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