What are Roundworms in Pets?

By: Trupanion Staff / Updated Oct 7, 2019

Roundworms in pets, of all the different types of parasitic worms found inside dogs and cats, is the most common. Almost every dog will be infected with roundworms at some point in its life, and often puppies are born with them, passed on from their mother. At up to 12 cm long and often found in large numbers, roundworms can cause your pet discomfort.

While roundworms are more common in dogs, there are three main types of roundworms that can affect both dogs and cats:

• Toxocara canis, which use dogs as a host
• Toxocara cati, which are found in cats
• Toxascaris leonina, which affects both animals

While the life cycles and genealogies vary, all three variants of this parasite survive by living on your pet’s sustenance and can cause risks to long-term health.

3 quick things to know about roundworms

• Roundworms are extremely common in young animals. Most dogs will be infected at some point in their early lives.
• Roundworms can also infect humans, another reason to visit the veterinarian if your pet shows symptoms.
• Different symptoms of roundworms in pets can indicate different stages of the worms’ life cycle. The parasites begin in the intestines, causing diarrhea and vomiting, but later move to the lungs and cause the dog to cough.

What do roundworms look like?

Roundworms can be 10-12cm in length and are usually white/cream or brown in color. They look like cooked spaghetti. They are generally thin and smooth-skinned, compared to tapeworms which are thicker and have bumps or ridges on their surface. This is because the tapeworm is made up of individual segments, while the roundworm is one, continuous body. On average, roundworms are also considerably longer than tapeworms.

Infection timeline

1. Pet inhales or consumes live roundworms or roundworm eggs, from food, milk, vegetation or soil.

2. If eggs were consumed, they hatch during the host’s digestion process, releasing the larvae.

3. If the animal is a suitable host, the larvae migrate to the lungs. From here, it may be coughed up.

Roundworm infection symptoms

Roundworms in pets produce a variety of symptoms. One of the most common is abdominal swelling, so be on the lookout for your pet’s stomach area appearing larger than normal. If you notice a change, gently feel the area with your hand to see if it seems bloated or firmer than normal.

Other symptoms may include lethargy, vomiting, abnormalities in the feces, or weight loss caused by the parasites feeding on your pet’s food intake. The animal is likely to be weaker than normal, too, expressing signs of fatigue. If you notice a combination of these symptoms in your pet, take them to the veterinarian for an exam.

Roundworms might also be spotted in a dog’s feces or vomit. The roundworm is long and smooth-coated and will appear as light strands.

Unlike many other conditions, the symptoms of roundworms may indicate the stage of infection. Roundworms start in the intestines and digestive system, causing vomiting, diarrhea and stomach inflammation. However, as roundworms develop into their adult stage, they move to the lungs and respiratory system. Your pet may cough and show signs of breathing interference. Spotting these symptoms can help diagnose how far along the infection is.

How can my pet become infected?

A domestic animal can be infected with roundworms in a variety of ways. Puppies and kittens are especially susceptible to infection, especially because an infected mother will often pass roundworms to her infants prior to birth through umbilical feeding, or shortly after birth via her milk.

Roundworms — and other similar parasites — are one reason puppies are commonly de-wormed by a veterinarian soon after birth. However, roundworms pose a risk to adult pets, too. A fully-grown dog or cat can pick up the parasites by eating infected food or water or feces found in soil, thereby ingesting roundworm eggs too small to see.

Are roundworms in pets dangerous?