Reasons why you might see worms despite worming

You gave your pet their regular wormer, so everything is good right? You took your dog out and there it was. The worm. Your cat came to curl up next to you and there was a little grain of rice and it was moving. We get questions about sources of parasites in pets regularly. Occasionally we’ll get questions from pet owners who are using parasite prevention but unfortunately still find worms from their pet. Albeit less common, we encourage people to have faith and go over these reasons why you might be seeing breakthrough parasites in your pet.

They didn’t actually eat the wormer.

• Some pet parents put their wormer tablet directly into their pet’s food and walk away to do other things, especially dog owners. This works great for good eaters like my goofy golden retrievers, but the pickier pets will sneak around that tablet like they’re Gordon Ramsey judging a food competition. You need to ensure your pet consumes the wormer. We know this may seem silly but pets can find all sorts of ways to get around eating pills, even when hidden in the best treats!

Your pet is exposed to heavier levels of parasites on a regular basis.

• Pets that are often in the following scenarios have a much higher potential of parasite exposure/infection: dog parks, dog daycares, group play boarding facilities, training events, flat/rental properties with common pet relief areas, areas with heavy wildlife populations (many can carry parasites), neighborhoods with high numbers of outdoor cats, pets that like to hunt (cats for rodents/birds) etc. More animal exposure means more opportunities for potential infection.

You are not worming regularly.

• Worming 1-2 times per year is not enough to keep parasites away. Many of our common parasites have life cycles that are completed in as little as a few weeks up to 2-3 months. Because of this, wormers are often recommended to be administered monthly to every 3 months to break the life cycle of the parasite if your pet has become infected. Checking with a vet to ensure you are using the right product for your pet and are treating frequently enough is a must!

The wormer you are using does not cover the type of parasite your pet contracted.

• There is not ONE wormer that protects or treats ALL types of parasites. We wish there was, however this makes appropriate and targeted worming for your pets lifestyle all the more important. Most of the common wormers on the market will prevent the major culprits including roundworms and hookworms, however not all products will also cover additional parasites like tapeworm or lungworms. Again, being aware of WHAT your wormer covers is important and can be discussed with a vet. There are some parasites out there that are not covered by common wormers and require a more specific treatment from a vet. For this reason, faecal testing is essential so we know what parasite is actually present. Side note – don’t forget many intestinal parasites are microscopic, so regular worming along with faecal checks at the vet are recommended.
• Common scenario: Pet owner giving cat a wormer that only treats roundworms and hookworms and cat becomes infected with tapeworms (contracted from eating a dead rodent), much to the owners dismay and frustration. The first assumption is the product does not work, when in reality the product is not a drug that treats tapeworms!

Your wormer works great, but your pet was infected in between doses.

• It’s important to make a distinction between wormers vs. flea/tick preventatives. Wormers are not preventing EXPOSURE to the parasite, but rather stopping the life cycle/killing off the parasite upon administration. Wormers do not remain in the system persay between doses to prevent infection like flea and tick monthly preventatives do. The hope is that regular targeted worming stops development of specific parasites and is given at appropriate intervals so that these parasites do not have the opportunity to grow into adults then shed eggs to infect other pets. Rarely pets, particularly those with higher exposure risk, will manage to pass an adult in between doses which may indicate a need for a change in worming frequency. Also note, pets may pass dead worms as well.

These are important considerations we like to cover with pet owners when they ask questions about wormers, their efficacy, and how they work. The wormers used in the veterinary community are extremely safe and effective products. We would say by far the most common reasons for people to have issues is they don’t realize what their wormer actually protects against or are not giving it at appropriate intervals! That’s what vets are here for, to be the reliable source of this information and make guided recommendations for what is best for your pet based on their needs.

Dr. Kirsten Ronngren, DVM MRCVS

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Common Gastrointestinal Parasites of Dogs and Cats

It’s probably safe to say that every pet owner wants their pet to be worm free. When I say worms, I’m talking about gastrointestinal (GI) parasites. Those pesky worms that we think only puppies and kittens get can actually infect pets of all ages. There are several types of parasites that infect our furry family members, but in this post we’re going to focus on a few common GI parasites you should be aware of as a pet owner. 

Roundworms 

Among our friends in the GI parasite family, roundworms are extremely common among dogs and cats. They are one of the most widely recognised, resembling spaghetti on their best days. Species causing infection are usually Toxocara, though others exist in the environment as well. But where do these parasites come from? Transmission between pets is typically faecal-oral, meaning your dog/cat gets faecal material from an infected animal in their mouth and swallows the eggs. You may think, “well my dog doesn’t eat other dogs’ poo” and that may be true. We have to remember that contact with faeces can be in many forms such as sniffing another animal’s rear end in the park, or even just stepping in soil that had faeces in it and then your dog licks its paws to clean them. The egg grows into an adult worm along the gut and then sheds eggs to be passed out in your pets faeces. Not very nice! Now let’s think about the sheer number of eggs that are passed. We’re talking thousands of parasite eggs from one adult worm, with the worst part being these eggs are microscopic. You won’t be able to see these with the naked eye. Not all pets will pass adult worms into the faeces, meaning that your pet could be infected and you may not even realise. This can end up being a problem for your pet, you and your family (we’ll talk more about this in our “Zoonosis” blog), and other pets that could become infected. Puppies and kittens can also be infected directly in the uterus from their mother, making roundworms in our young babies common and important to address. In addition to the roundworm issue being disgusting, it can cause medical issues for your pet including diarrhoea, vomiting, weight loss, and potentially even intestinal blockage in severe cases. Roundworms are found far and wide including places like the park, the beach, walking paths; anywhere that dogs might poo. It is important we recognise this is a risk and make sure we are deworming our pets regularly with the direction of a licensed vet.

Hookworms

Similar to roundworms, hookworms are also in the same family, however they contain a hook like mouth on the adult worm that allows them to behave a little more aggressively. Hookworms are also spread via the faecal-oral route. Signs of infection may include diarrhea, but in severe cases we may also see blood in the stool or anemia (low red blood cell count) due to bleeding in the intestinal tract from the parasite. Both hookworms and roundworms may also try to migrate  to other organs and cause serious disease. Hookworms in particular are known to cause conditions in humans called visceral larval migrans (migration and trauma to other organs) and cutaneous larval migrans (migration to worms under the skin). This makes deworming your pet even more essential for you both.

Tapeworms

There are thousands of parasites that can infect our pets, but I think one that people recognise above others are tapeworms. Tapeworms are commonly spotted by owners with or without clinical signs like diarrhea. Vets get many calls about “small worms coming out of the patient’s behind”. These little worms resemble moving grains of rice, and are the major indicator of tapeworm infestation. The most common origin of tapeworm infestation is actually a flea infestation. Fleas harbour the immature form of the tapeworm Dipyllidium, and when pets groom/lick themselves and swallow adult fleas, they also consume the tapeworm egg. The worm then matures in the gut and both segments of the adult worm as well as eggs are passed in the faeces. There are other common species of tapeworms, primarily of the Taenia family, that our pets contract by consuming what is called the intermediate host. This is a host that helps the parasite complete its life cycle and mature, such as a rabbit or rodent. 

Some other common gastrointestinal parasites include coccidia, giardia, whipworms, and lungworms (these are actively passed through faeces even though they reside in the lung). I could write pages and pages on these, however I think that it’s important pet owners are familiar with some of the most common to help them be proactive when it comes to prevention. Prevention is always better than treatment if we can help it.

Top Five Parasite Tips for Pet Owners

1. Make sure a vet is involved in deciding which wormer is best for your pet.
2. There is not ONE dewormer that treats ALL parasites, meaning there is not a one shot treatment for all species. This makes #1 all the more important. 
3. Most intestinal parasites are NOT visible to the naked eye and may or may NOT cause clinical signs like diarrhea. It is important that we regularly deworm our pets AND regularly have a faecal sample checked by a vet to make sure we aren’t missing low grade infections. 
4. Prevention is typically cheaper and safer than treatment after a problem is detected. 
5. HUMANS can also become infected and ill from parasites that infect our pets, making awareness and treatment essential to all of our health. 

Dr. Kirsten Ronngren, DVM – MRCVS

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