Ask a vet: how to tell if your pet has worms

How can I tell if my pet has worms? 

Worms, germs and creepy crawlies. Yuck. Who wants to think that their cat or dog has worms? Fortunately, your veterinarian thinks a lot about the different parasites that may harm your pet. Let’s talk about the common roundworm in cats and dogs. 

Puppies and kittens can be born with worms. 

How is that possible? Let’s look at mom’s role in passing worms to her puppies or kittens. 

• Toxocara cati and Toxascaris leonina are two species of roundworms that can live inside cats. Toxocara canis and the same Toxascaris leonina are the two species of roundworms that can live inside dogs. 

• Roundworms infect cats and dogs in three major ways; dog roundworms have one extra path. 

• Eating a mouse or other rodent (transport or paratenic host), which carry roundworm larvae (developing worms). 

• Eating dirt contaminated with infective worm eggs during normal grooming of paws and fur. 

• Kittens can be infected by nursing from a mother cat who has roundworms in her system. 

• Puppies can be infected either through nursing from an infected mother or directly in the uterus. 

Infective eggs and worm larvae of Toxocara go through a wildlife cycle in the pet’s body. 

• The eggs hatch in the intestinal tract and burrow their way out of the intestines and into other body tissues. 

• In cats and dogs, most worms will migrate to the lungs, although they can end up in the liver, muscle or mammary glands where they form little walls around themselves, becoming encysted. 

• Those larvae that reach the lungs burrow into deeper airways and eventually travel into the pet’s throat. This stage of migration causes coughing in the cat or dog, which may be mistaken for other conditions like kennel cough. In heavy infections, pets can develop severe pneumonia. 

• Coughing up these little, microscopic larvae allow them to be swallowed back into the intestines. I know. Gross, right? 

• If the larvae have moved into the mammary glands of nursing mothers, kittens and puppies can be infected by drinking contaminated milk. 

• In pregnant dogs, the larvae want to move across the placenta and directly infect the developing puppies in the uterus. 

• Once the roundworms are adults, they “rent space” inside the intestines, causing damage and blocking proper digestion of nutrients. This is where they will mate and produce eggs to be passed into the feces. The life cycle can then start all over again. 

How can I tell if my pet has roundworms? 

• Because of the weird and incredible life cycle of roundworms, we can expect most puppies and kittens to be infected.  

• Occasionally, puppies and kittens will cough up or vomit roundworms. Rarely do we see adult worms pass into the poop. Roundworms are thin and long, typically 4-6 cm in length. 

• Low-level infections may cause only subtle signs in your pet. Heavier worm burdens can steal nutrients and contribute to pot-bellied tummies, poor hair coats, vomiting, diarrhea, pneumonia and slow development in puppies and kittens. 

• Fecal examinations by your veterinary team help to determine which parasites are present, including eggs of roundworms and other worms. One-celled parasites like Giardia and coccidia may also be detected in infected pets. 

• Small, flattened segments in the feces or around the anus may actually be tapeworms. Tapeworms are a different species and may require an alternative treatment than roundworm infection products. 

• Especially, in summertime, you may see small white wriggling larvae in your pet’s poop. These creepy crawlies are generally fly larvae from the environment and not roundworms. 

• The eggs are microscopic and cannot be detected with the naked eye. Infective eggs in the backyard can become a source of chronic infection, especially in homes or kennels with breeding animals. 

• If you are not sure about your pet’s parasite status, check with your veterinary team for the best advice about diagnosis, treatment and prevention. 

How can I treat and prevent roundworms? 

Over the counter dewormers may seem like a good idea to keep your dog and cat parasite free. Most products are relatively safe. The thing is safe does not always mean effective. Parasite resistance and minimizing the worm population without addressing the encysted larvae can lead to ongoing problems for your pet. 
 

Never use a product marked for dogs in cats. Some of these products are poisonous to cats. 
 

Based on where you live in Canada, your pet’s lifestyle (indoor/outdoor), and their overall health status, your veterinarian will recommend a customized parasite treatment and prevention plan. There are very effective veterinary products to prevent serious diseases associated with intestinal parasites. Always follow the full directions and repeat treatment as directed for best outcomes. 

Do I have to worry about catching worms from my pet? 

Many parasites are species-specific, meaning they only live in dogs or cats or people. There are, however, parasites that can cause disease across species and may transfer from pets to people. Your veterinary staff can discuss which of these zoonoses or zoonotic diseases are a concern for your home. 
 

Catching roundworms (Toxacara canis and Toxocara cati) from your dog or cat is pretty difficult because it takes at least one to four weeks for eggs to become infective once they’ve passed out of the pet’s intestines. Responsible hygiene, daily poop clean up, handwashing after petting animals and discouraging face licking will avoid infection most of the time. 
 

Most roundworm infections in people come from working or playing in dirt where animals have passed feces. Uncovered sandboxes and gardens used by cats for toileting are a common source of infection in children.  
 

Because of the tendency for roundworm larvae to migrate through tissues, they can cause non-specific signs such as fever, muscle soreness, weight loss and rashes. In more severe cases, the larva can migrate to the liver, lungs, and hearts (visceral larva migrans or VLM), the brain and spinal cord (neural larva migrans or NLM) and the eyes (ocular larva migrans).  
 

Human pediatricians and family physicians should be consulted if you have questions about the health of your family. 

Pet insurance can help with the cost of vet visits 

Parasite prevention is included on Secure 4 plans for both dogs and cats. Learn what’s covered by Petsecure and get a free quote today.