We've all seen the unique variety of things dogs will put in their mouths, which makes it easy to see why parasite treatment and prevention is necessary. In Manitoba, we have plenty of ticks and mosquitoes, making diseases like Heartworm disease and Lyme a danger to our dogs. With the increased number of dogs travelling with their humans, and puppies brought home from afar, we are also seeing some parasites not typically found in Manitoba.
Read below for some information on the parasites we commonly find in our pets.
There are several intestinal worms that we worry about infecting our dogs - Roundworms, Hookworms, Whipworms and Tapeworms. These intestinal parasites can affect growth and development in our puppies, cause decreased health in adult dogs, and can also be a dangerous zoonotic risk if passed on to humans (especially children)! Most infections can be picked up through routine fecal analysis looking for worm eggs. Treatment of intestinal worms often involves multiple treatments of medication spaced several weeks apart in order to ensure all adult worms are removed from the intestines. Below is some information on the most common intestinal worms we see in our dogs.
Roundworms - Infection occurs through ingestion of infective eggs from the environment - either from contaminated soil, from ingesting an infected rodent, or through the mother's placenta and/or milk in newborn puppies. Once ingested, the larvae migrates throughout the dog's intestines, liver and lungs (depending on species) before growing into an adult and laying eggs that pass in the dog's feces. These worms can grow up to 7 inches in the intestines. This worm does pose a risk to humans! If a human ingests an infective egg, the larvae travel randomly throughout the body before dying, and in many cases, end up in the eye, causing blindness. Eggs are fairly hardy in the environment and can survive freezing temperatures.
Hookworms - Infective larvae found in the environment can infect its host in several ways - either directly by penetrating the animal's skin through the feet or belly or any skin touching the ground (these little guys have teeth!), or by the dog self-grooming after contact with infected soil, or by ingestion of an infected animal or insect. These worms can also be passed onto a newborn litter of puppies via an infected mother's placenta and milk. Hookworms actually suck blood from their host, which can cause anemia in severe infections. These infective larva can also burrow into human skin if contact occurs with contaminated soil. Direct ingestion of contaminated dirt will also cause infections in humans.
Whipworms - These worms are also ingested from contaminated soil. They live in the dog's intestines, sucking blood and producing more eggs. Treatment for these worms is especially lengthy considering it takes almost 3 months for the life cycle to be completed. Furthermore, the eggs are VERY difficult to remove from the environment, leaving soil where an infected dog has defecated contaminated for years. These worms can not readily infect humans.
Tapeworms - There are several types of tapeworms that can infect our dogs. All tapeworms go through a cycle which includes an intermediate host (that is, the dog sheds the tapeworm eggs, which are ingested by either a flea, a grazing mammal, or a rodent for example, where the tapeworm develops further. The dogs must then ingest the immature tapeworms from the intermediate host to finish the life cycle). Luckily tapeworms are easily treated, but care must be taken to treat flea infestations and/or prevent scavenging of carrion to prevent re-infection from occurring. Tapeworms can also infect humans through the same mechanisms, but not directly from our dogs.
Heartworm disease is a real risk in our area. It is literally, a worm, transmitted by mosquitos, that grows into an adult in a dog’s heart. This results in an inflammatory response, and can lead to heart failure and death. Luckily we have a simple blood test that can detect heartworm disease before heart failure develops, leading to a better prognosis (the 4Dx "heartworm/lyme" test). And if a dog does contract heartworm disease, the treatment to get rid of the worms can be life-threatening in itself, and it can be quite expensive. Therefore, we always aim to prevent it from occurring in the first place with monthly heartworm prevention. It is important to remember that the heartworm parasite lingers in the area mainly due to dogs who are not on prevention, and in our wild animals such as foxes and coyotes. Also, because mosquitos often make it indoors, it is still important for dogs (and cats!) who mostly live indoors to be on prevention as well.
Often, we can visualize external parasites on our dogs (ticks, fleas and lice) if we look closely enough. However parasites such as mites (which can burrow under the skin and hide) and even some cases of flea infections (they can jump on and off of our dogs) can be almost impossible to visualize. Diagnosis often requires skin scrapings to look under the skin and in some cases medication trials. There are also several options for treatment that will prevent infection of fleas and ticks.
Ticks - We see several types of ticks in Manitoba including the common dog tick and deer ticks, which can transmit the parasite responsible for Lyme disease. Tick bites themselves can cause an inflammatory reaction that can predispose to the formation of hot spots (a very uncomfortable/painful rash)
Mites - There are many different types of mites that can infect our dogs. Ear mites, Sarcoptic mites (causing Scabies or "Mange"), Demodex mites and so on. Some of these infections cause extreme itchiness and secondary infections. Some are transmissible to humans.
Lice - These little guys can cause itchiness and secondary bacterial infections in dogs. Luckily, dog louse are species specific so will not be passed to humans or other animals.
Fleas - these little guys are often dropped off by infected wildlife and can quickly infect entire homes. Flea bites can cause allergic reaction in our dogs leading to intense itchiness. Furthermore, fleas are the intermediate host in one type of tapeworm infection. These guys will bite humans too and can give tapeworms to humans if ingested.
Giardia - this protozoan parasite is picked up from a contaminated environment (often dirty water), similar to other intestinal parasites that are passed in the feces. It typically causes diarrhea and can readily infect humans. This parasite is hardy in the environment.
Coccidia - this small parasite infects the intestine, causing diarrhea (sometimes bloody). Small infections will not always cause diarrhea, but will act as a source of infection for other animals by contaminating the environment. Some species of coccidia can infect humans (cryptosporidium is a particularly unpleasant example). Routine fecal analysis often will lead to detection of these little oocysts.