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Roundworms: all you need to know
Of the different types of parasitic worms found inside dogs, the roundworm 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 in an infected animal, roundworms can cause your pet real discomfort.
While roundworms are more common in dogs, there are three main types of roundworm 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 nasty parasite survive by living on your pet’s sustenance, and can cause discomfort and even risks to long-term health.
FACT FILE: 3 things to know
- Roundworms are extremely common in young animals. In fact, the majority of dogs will be infected at some point in their early lives.
- Roundworms can also infect humans, even more reason to visit the veterinarian if your pet is showing symptoms.
- Different symptoms of roundworms can indicate different stages of the 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 a bit 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. Roundworms are also considerably longer than tapeworms, on average.
Infection timeline - what happens?



What are the symptoms of roundworms?
In both dogs and cats, roundworms produce a variety of symptoms which can indicate the problem. 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 you 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 intake of sustenance. The animal is likely to be weaker than normal too, expressing signs of fatigue and lethargy. If you find a combination of these symptoms in your pet, take them to the veterinarian for examination.
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 in your animal’s excrement.
Unlike many other conditions, the symptoms of roundworms may actually indicate the stage of infection. Roundworms start in the intestines and digestive system, causing symptoms of vomiting, diarrhea and stomach inflammation. However, as time passes and the roundworms develop into their adult stage, they move to the lungs and respiratory system, so your pet may cough and show signs of breathing interference. Spotting these symptoms can help to diagnose how far along the infection is.
How could 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, since 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 that 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 be noticeable.
Are they dangerous? - the health implications
In adult pets, roundworms pose little threat to the animal’s health. An adult pet will likely suffer the symptoms listed above (vomiting, swelling and weakness), but should return to their usual bouncy-self once treated.
However, in young pets, the roundworm can present the risk of more worrying long-term damage. Roundworms thrive by feeding on the sustenance consumed by its host, draining large portions of their food intake and not leaving enough for the hungry pet to remain healthy. Over time, if untreated, this greedy snatching of all the good stuff in your pet’s food can lead to malnutrition, which in turn can impact growth and development. A young pet with untreated roundworm could grow up frail and weak compared to its siblings, and not reach its full potential as an adult. For this reason, it is crucial that if you notice the symptoms associated with roundworms you take your pet to be examined by a veterinarian right away.
Getting rid of roundworms - recommended treatments
Treating roundworms — like many pet parasites — is a simple and painless procedure. Your veterinarian will give your pet a single oral dose of de-worming treatment, and the pests will find their way out of the system. You may be asked to take samples of their stool at weekly or fortnightly intervals after treatment, to ensure that the problem has been cleared. Your veterinarian may also recommend a heartworm de-wormer, which often also tackles and prevents roundworms.
Home de-worming treatments are also available over the counter, though their reliability and effectiveness varies. To be sure of a healthy pup or kitten, and to minimize the risk of the problem reoccurring, it is best to seek the help of a veterinarian.
Thinking ahead - tips for preventing infection
There are a number of easy steps owners can take to minimize the chances of picking up parasites. Here’s our simple 4-step plan to keep your pet roundworm-free:
- DE-WORM IN EARLY LIFE: Get rid of roundworms passed from your pet’s mother by arranging de-worming treatment fortnightly until the age of 8 or 10 weeks.
- THINK HYGIENE: Keep your pet’s living areas clean, removing and disposing of any feces in a sanitary way to prevent transmission.
- LESS BUTT-SNIFFING: They love to do it, but sniffing around the behind of a fellow canine or feline could see your pet inhaling dangerous roundworm larvae.
- NO WILD SNACKS! Try to discourage your pet from catching and eating wild animals, such as squirrels or rodents, which may be carrying roundworms.
This article is intended as an informative guide for pet owners, but is not a replacement for veterinary care. If you believe your pet may be infected with roundworms, seek professional advice from a veterinarian.