This week we are going to talk about worms. Not the very helpful earthworms that keep our gardens healthy, but the very unhelpful and unhealthy ones that can make all animals – including humans – very sick. Gross to think about, gross to talk about, but even more gross if you ignore them and don’t take the steps to protect yourself, your family and your animals.
The worms that we are worried about are the type that need animals as part of their life cycle to survive, and that cause a variety of problems depending on where they are in the host’s body. For example, heartworms grow to their adult size in the heart, lungworms in the major airways, some worms stay in the gut and others like to migrate around the body. It would be nice to think that these are only problems of exotic countries, but the reality is that we do live in an area where some worms are a problem. We are now also more mobile with our pets, taking them with us on our travels and exposing them to worms that we may not have here. Heartworm is a great example of a risk that is not present in our area, but southern Alberta and the Okanagan areas are predicted to have a very high-risk summer for heartworm exposure.
In our area, the particular concerns are roundworms and tapeworms. As well as their effects on our animals, certain species can cause disease in humans, especially the young or unwell. A species of tapeworm is currently causing concern in the human health world — a European species that is known to cause high mortality in less than 10 years for untreated humans. Four cases were diagnosed in humans last year in northern Alberta alone. It is contracted by humans being exposed to the eggs from infected dogs, coyotes, foxes, wolves or cats. The highest areas of infected feces sampled have been in downtown Calgary, Saskatoon and areas in BC. Previously, tapeworm species of concern were in animals that ate large amounts of raw meat, not likely the case in those urban areas sampled.
Unfortunately, it is not easy to see if your pet has worms. By the time there are changes, either in the body as a whole or by seeing evidence if the feces, the infestation is likely to be severe and longstanding. Physical signs of worms look very much like other diseases that draw heavily on the body reserves – weight loss, poor coat, distended belly, changes in the stool, colic in horses, or signs like coughing and lethargy may be seen, but the majority of animals with worms look completely normal! Seeing evidence of worms in the feces is equally misleading. Roundworms passed are the typical ‘spaghetti’ stool that grosses everyone out (horse roundworms can be up to 40m in length!) but other worms and their eggs are not that obvious. Eggs of all species of gastrointestinal worms can be found in stool, but only with the aid of a microscope and they are not necessarily passed regularly. This means that if eggs are seen on a single stool sample, it is definitely positive, but not finding eggs does not mean that there aren’t any worms. Your veterinarian will often ask you for several samples to minimize the chance of a false negative result.
Due to the difficulty in diagnosing, it is commonly recommended to keep your animals on a regular deworming program to control their worm load. Deworming programs are created by your veterinarian based on your animal’s risk, and the dewormer appropriate for the species. Dewormers typically kill adult worms, and reinfestation occurs at the next exposure. Deworming once a year is often not enough. Very high risk dogs and cats may need deworming monthly. Deworming programs may also need to change if your animal is leaving the area.
Another basic way to protect yourself and your loved ones is to thoroughly wash hands after having contact with your animals or their feces, BEFORE eating or touching your face. Washing your hands well after gardening also minimizes your exposure to eggs in the soil, as well as washing all vegetables and fruit thoroughly, especially if they come from plots that dogs or wild canids can access and deposit feces. If you have any questions or concerns about worms, your veterinary team is a great resource of how to protect humans and animals alike.
Dr. Katharine North has been a resident and active participant in the Fort St. John community since her family immigrated to Canada from the United Kingdom as a child. Dr. North spent many hours at the North Peace Veterinary Clinic as a student and joined the practice as a veterinary associate upon graduation.