Let's Talk About Parasites!

They're gross, they're creepy, they're crawly and they're….INVADING!! Yes, parasites are an unfortunate part of our world but they are a part of our world nonetheless. There are many different types of parasites out there that affect our animal friends; that live on the outside and the inside of the body and some are contagious to us too! Because they can be transmitted to us, it is important to learn about them, signs to watch for and how to prevent them to protect not only our animal friends but us too. Let's look at our little parasite "friends" a little closer shall we?

Ectoparasites vs. endoparasites

We typically categorize our parasites into two different categories called ectoparasites and endoparasites. Ectoparasites are the creepy crawlies that live on the outside of the body. These include fleas, ticks, mites and mange just to name a few. These little buggers often cause a lot of itching and skin issues for our pets. They can be very difficult to get rid of once your pet has them. Fleas, ticks and certain kinds of mites and mange can be transmissed to us as well causing us the same grief. We also know that fleas and ticks can carry a lot of diseases that can be a major problem in both the human and animal world. Endoparasites are parasites found inside the body. Example of these would be roundworm, hookworm, tapeworm, heartworm and giardia just to name a few; there are many different types out there. While most of the parasites don't cause a major problem, they are certainly not a healthy thing to have living in your body and some of these critters can also be passed to us which is never a good thing. Because there are so many, we will look at a few of the more common parasites a little bit closer.

Roundworm and Hookworm

Roundworm and Hookworm are two intestinal parasites (meaning they live within the gut) that are probably two of the most common parasites we see in veterinary medicine. They live off the nutrients absorbed into the gut every time your pet eats. The adult worms attach to the intestinal wall and that is where they live and breed. They then produce eggs which are microscopic and leave the body with the feces which is where they are introduced into the environment and then ingested by another animal and then the cycle starts all over again. This is why, even though you are not seeing worms in your pet's feces, it doesn't mean they are not infected. Healthy adult worms will not leave the intestines for any reason and the eggs are microscopic. Dying or dead worms let go of the wall and will be excreted by the feces so only then will you actually see the parasites. These worms "steal" the nutrients from your pet so you will often see symptoms such as losing weight, poor hair coat condition, off and on diarrhea and, in some severe cases, vomiting. These parasites are also zoonotic meaning they can be transmissed to us as well. The most common problem with these parasites in people is that they are what we call transmigrans meaning in people, they move out of the gut and travel to other places in the body. Roundworms often like to travel to the eyes which can cause acute blindness or permanent retinal damage, especially in children.

Roundworms can only be transmitted through ingestion so it can be harder to contract. Hookworms can actually be absorbed through the skin, they do not require ingestion to affect us, and will cause lesions, most commonly on the feet.

Thankfully, these parasites are easily prevented. For dogs and cats, monthly heartworm preventative such as Heartgard Plus, Revolution and Sentinel Spectrum protect against these gross parasites and help protect your pet but it must be given monthly in order to be effective. To help protect you, be careful with kisses! You never know where your pet's mouth has been or what they have eaten so do not allow them to kiss you on the face and always wash your hands after playing with a pet you are not as familiar with. Keep your yard clean of feces and always wear shoes when outside to protect your feet. Remember, wild animals can contract these parasites as well so do not allow your pet to ingest their feces and keep away from them as well Wash hands thoroughly after handling feces and have a fecal checked on your pet at least once-a-year, or more frequently if they are having problems.


Whipworms are another intestinal parasite that can be fairly common though less so than Roundworm and Hookworm. Whipworms are often found in rabbit feces as the main source of infection though deer can carry it as well. It produces the same symptoms as the other intestinal parasites but can often be harder to get rid as it does not always respond as well to dewormers which we use to treat parasites. This one is thankfully not zoonotic so we do not have a concern about it in us but it can affect any of your pets. For dogs, Heartgard does not protect against this parasite but Sentinel Spectrum, will so if you have a common rabbit "problem" in your area and your pet likes a little "treat" it wise to keep them on Sentinel Spectrum monthly for protection. For indoor/outdoor cats or outdoor only cats, we would recommend deworming regularly with a dewormer.


Tapeworms are a much more common type of intestinal parasite than people realize. There are a few different types of Tapeworm. The most common variety is spread by fleas. When your pet has a flea problem, they will scratch and bite at themselves because they itch. When they do this, they will often unintentionally swallow a few fleas which can carry the tapeworm larvae that will then mature and develop inside of your pet causing a Tapeworm infection. The two other types are carried by rodents and small mammals but the concept is the same. If they ingest their feces or eat those rodents, they can get a Tapeworm infection as well. Tapeworms are much harder to find through fecal testing and we will often get a negative result even though they are there because they shed their eggs differently. Instead of laying their microscopic eggs, they shed segments of themselves that contain tons of eggs at once. These segments are then ingested by a flea, rodent or your pet and then the cycle starts again. Without the segments, sometimes, there can be no evidence of them at all and sometimes tests will not show their presence. We usually discover them when an owner tells us they are finding little white things in their pet's poop that are about the size of a grain of rice, these are the segments of the tapeworm. These segments will often be found in bedding, feces or around your pet's rectum. If your pet is a big hunter, they are at a higher risk for Tapeworm infections. Once your pet has the infection, it is best to call your veterinarian to find out what to do next. For dogs, Tapeworm can be prevented with monthly Sentinel Spectrum. For cats that go outside, a monthly deworming medication may be recommended but you should speak to your veterinarian for the best plan.


Giardia is a type of protozoa that prefers a wet environment to survive. This parasite tends to breed in moist soil and loves stagnant water sources such as ponds, puddles, outdoor water dishes and river/creek banks. This parasite is microscopic so you will never see it in the stool and their eggs are also microscopic. It tends to cause more problems in younger animals but can affect older ones too. This parasite lives in the GI tract and will often cause off and on diarrhea, bloody diarrhea and sometimes vomiting. This parasite is very tricky to get rid of in comparison to other parasite friends. There is no drug specifically designed to kill this type of parasite but there are a few that can assist in killing it. This parasite is also hard to get rid of because it is easily found in the environment and can stay dormant for years, so even when you think it is beaten, your pet can catch it again. The eggs, also known as cysts, can live in the soil burrowed deep down until conditions are just right and then hatch out burrow out of the soil and affect your pet. This means that your pet licking where giardia has buried in the soil can affect them. The cysts also do not live inside the body or just drop out in the feces like other parasites. When your pet poops, the cysts can be in the feces but can also stick around the edges of your pet's rectum. Then, when your pet licks back there to clean, they can re-infect themselves. Giardia is a hardy little protozoa that likes to live! It takes a combination of drugs, cleaning and diligence to defeat this little guy. Once a pet is infected and diagnosed with a fecal test, it is important to keep the yard free of all feces including wild animal and bird feces as they can be sources of infection. Pick up all feces immediately so it does not have a chance to contaminate the soil and keep your pets away from all stagnant water sources which are the breeding grounds for this parasite. Though it is rare, this parasite is also contagious to us! People with compromised immune systems such as children, the elderly and the sick are at risk for contracting this protozoa. It is important to practice good hand washing, no kisses on the mouth and keep the house and countertops especially where food is prepared clean to lower the risk. There is, sadly, no preventative for this protozoa so it is important to practice clean habits to prevent.


Fleas are everywhere and extremely hard to get rid of! These small bugs can be found in any environment and breed at an unbelievable rate. One flea can produce about 500 eggs during her lifespan which means, if you see one flea, there are hundreds you don't see! Half the population of a flea infestation is the eggs. These eggs typically take about 12 days to hatch. The female flea takes a "blood meal" and immediately begins laying eggs. These eggs are usually out in the environment and are triggered to hatch when they sense vibrations such as you or your pet walking by. The larvae hatch out of the eggs and begin growing. The larvae eventually spin a cocoon around themselves and become pupae. They can stay in this stage for up to 1 year! Which means if conditions aren't right, they stay in the protective stage until food aka your pet becomes plentiful again, they will then emerge as adult fleas and the cycle starts all over again.

Adult fleas are fairly easy to kill with different types of pesticides and the eggs/larvae can be killed as well but the pupae's hard outer shell is extremely difficult to penetrate making them extremely difficult to kill. This is why getting rid of fleas is so hard. You can treat your house and pets but if you are not consistently doing it, the pupae will continue to hatch and more fleas will appear.

This is why it is recommended to treat all of your pets and your household for at least 3 consecutive months. This will break the flea life cycle and finally get rid of them. Fleas can also survive a freeze/thaw cycle meaning if our winter is not cold enough, they will live. They can also survive the winter in your home so once they are inside; cold weather will not stop them because they are protected. Because fleas feed on the blood, they are also notorious for spreading disease. The bubonic or black plague was believed to be started by rats originally but it turned out it was the fleas on the rats passing it around. Fleas can carry different kinds of blood-borne pathogens that affect pets and people alike. They can also carry parasites like Tapeworm as we discussed previously. This is another reason it is extremely important to prevent fleas. As you can see, this is quite a process and can become very costly in the end between home treatments and pet treatments. This is why prevention is the best medicine. Products such as Frontline Gold for cats and dogs, Simparica for dogs and Nexgard for dogs given monthly will kill any fleas that decide to jump on your pets from the outside and will die before they get a chance to create a problem in your home. We don't just recommend treating your pets that go outside but treating your indoor-only pets too! We are not the fleas' preferred target but are easy to hitch a ride on. Even if you are treating your pets that go outside that doesn't mean you're not bringing them inside. Protecting your indoor-only pets will make sure the fleas do not have a blood source of any kind to prevent a problem. You can also discuss treating the outside of your home with professionals. Always make sure to let any exterminators know that you have pets and find out the restrictions on different products they may recommend.


Ticks are becoming more and more of a problem every year. Ticks are not just a "southern" problem anymore. There are several species of ticks and almost all of them can be found in Michigan this means tick protection is becoming more and more necessary to keep ourselves and our pets safe. Ticks feed off blood and they do not care who their source is. They will feed off any living creature including reptiles, wild animals, birds, our pets and us! Ticks are members of the arachnid family which means they are related to spiders, gross!! When the weather gets warm (anything higher than 40 degrees F is acceptable to these guys), they begin to climb up taller vegetation and put their little legs out and wait for an unsuspecting creature to walk by them. Ticks that have not taken a blood meal are extremely small and will often not be noticed just sitting on a blade of grass or plant. When the animal walks through the grass, the tick grabs hold and then burrows into the fur to find a good place to bite. The tick inserts its head into the skin along with a numbing agent so the victim does not suspect it is happening and then begins to take a blood meal. A tick can stay attached anywhere from 24-48 hours depending on how much blood it needs, so finding an engorged tick on you or your pet means that little bugger has been on there a long time! Like fleas, because ticks feed on blood, they can carry different blood-borne pathogens as well. Lyme disease is a fairly common disease that affects both people and animals. This disease can live dormant in dogs or people for periods of time and then they will begin to show symptoms. Symptoms are often very vague in our dog friends, they can have lethargy, generalized pain, stop eating or just act like they don't feel good making it often hard to diagnose. This is one of the reasons Westarbor performs a heartworm test that also checks for 4 tick-borne illnesses including Lyme disease; to try and catch it even when your dog is not showing symptoms. This disease is typically treated with antibiotics and is curable but can come back. Thankfully, a positive dog cannot give this disease to people directly. It must be contracted through a tick. There are other tick-borne diseases that can affect our pets and some are deadly. It is very important to protect all of our pets from these awful creatures. Frontline Gold for dogs and cats, Simparica for dogs and Nexgard for dogs are all designed to kill ticks before they can transmit diseases. Ticks have an extremely hard exoskeleton that can be hard to penetrate making ticks very hard to kill. They also can survive some of the harshest conditions. It can take up to a month of frozen conditions to actually kill a tick but often they will just go dormant which means the moment it becomes 40 degrees outside, they will come to life again and begin searching for their prey. That means winters that are not consistently freezing will allow the ticks to live. All of these products are proven to work, work well and keep working for up to a month to keep your pets safe. Tick infestations are EXTREMELY difficult to get rid of and will require an exterminator to help your home so the best medicine is preventative medicine.

Parasites are disgusting but unfortunately they are a part of our world just like every other living creature. We cannot re-iterate enough that prevention is the best medicine. This is why Westarbor Animal Hospital doesn't just recommend seasonal prevention but recommends it all year round! It is impossible to predict the type of weather we will have and our parasites are hardy creatures set on survival so they will do whatever it takes to survive. Year-round prevention means you are doing your absolute best to make sure they don't win. Protecting your pets will help protect you! Contact Westarbor Animal Hospital today to learn more about the different preventative we offer, their specials and to pick more up today!

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