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Importance of Parasite Prevention in Dogs

Parasites can cause diseases and uncomfortable symptoms both internally and externally depending on the type. Here, our Novato vets talk about internal and external pests and share information about parasite prevention for dogs.

What are the effects of parasites on dogs?

Parasites are pests that can live externally on the fur and skin of your pet or internally, usually in the gastrointestinal tract. These parasites live strictly off of the blood and vital nutrients provided by your pet's blood.

Some cause irreversible, severe damage to your dog's organs. The many types of dog parasites include hookworms, heartworms, tapeworms, lice, ticks, and fleas. 

In this post, we'll take a look at some common parasites in-depth and explain why parasite prevention in dogs is so essential to their health, and how your vet can help.

How does a dog contract a parasite?

Some of the parasites that most commonly infect dogs, but are also preventable, include:

External Parasites

External parasites live on the skin of your canine companion, biting on the surface and feeding. The two most common are fleas and ticks:


Fleas are a type of external parasite that need the blood of a host, such as your dog, to survive. Once these tiny parasites have made themselves at home on your pet they will begin to multiply at an astonishing rate. Some estimates calculate that for every adult flea you find on your pet, there may be 100 or more immature fleas hiding throughout their coat. Not only that, but if your pet has fleas there is a good chance that these parasites are also invading your home, hiding in carpets and soft furnishings.

Many dogs are allergic to the proteins left behind when fleas bite, which causes the area of the bite to become intolerably itchy. When this happens pets often scratch and groom excessively leading to raw damaged patches of skin, fur loss, and in some cases infections. Additionally, fleas have an added danger in that infected fleas can also transmit tapeworms to your pet.


Ticks are external parasites that rely on 'hosts' for transportation and food. A host is a person or animal that the tick lands on and begins feeding on. Ticks feed on the blood of their hosts, including humans and animals.

These pests are common around the world and many different species are found across North America. Each type of tick comes with serious risks to pet health and human health. Tick's saliva contains a variety of germs and bacteria which can be transmitted to the animals and people they prey on. These bacteria can lead the host to develop conditions such as Rocky Mountain spotted fever, Canine Bartonellosis, Anaplasmosis, Ehrlichiosis, alpha-gal allergy, or Lyme disease.

Internal Parasites

Internal parasites are most commonly found in the intestinal system of animals and people. Some of the most common internal parasites are:


Roundworms are a common parasite in pets. As the name implies, they’re large roundworms that live in the intestines and cause ascariasis. Kittens and puppies generally become infected with roundworms through nursing and can catch contact with this parasite by eating the larvae found in the feces of other infected animals. Roundworms are a zoonotic parasite, which means humans can also become infected with roundworms.

If your pet has roundworms you may notice symptoms such as diarrhea, lack of energy, weight loss, or vomiting. In pets with few worms present, there may be no signs of infection, but you may see them in your dog's stool or vomit. Since roundworm infection symptoms aren't always easy to spot, it is important to have your pet attend annual checkups at your vet's office and have yearly fecal exams.


These are flat, long, segmented parasites that attach to the walls of the small intestine. Dogs are most commonly infected by the Dipylidium canine species, but several types are known to infect pets. The way most pets get infected is by swallowing a flea that has been infected with the tapeworm, which can easily happen while they are grooming or as a response to flea bites.


Heartworms or Dirofilaria immitis, are protozoan parasites that live in the heart, lungs, and surrounding blood vessels of dogs. This disease is transmitted by infected mosquito bites, when eggs find their way into your pet; the larvae travel through the bloodstream for several months, finally settling in the heart and pulmonary arteries.

These infections can go undetected for months until the condition reaches more advanced stages when damage to the pet's internal organs has already begun. Treatment for heartworm disease is available however it is toxic to the pet, and can be very expensive. For this reason, many pet parents find themselves having to make the heartbreaking decision to euthanize cherished pets diagnosed with heartworm disease. 

How to Prevent Parasites in Dogs

Naturally, after discovering how many parasites our dogs can contract and the potential effects on their health, the next question pet owners have is, 'How are parasites prevented?'.

The best way to protect your dog and prevent parasites is to keep up with their vaccinations. Your vet will be able to advise you of a vaccine schedule that suits the needs and lifestyle of your pet. Make sure your dog goes for an annual wellness check so your vet can test for infestation.

Why do dogs need parasite prevention?

Parasites can pose a significant danger to even the healthiest dog. That's why parasite control for dogs including a variety of parasite prevention practices and products is important to protect your pooch and your family. 

Preventive care for dogs is an essential part of their routine healthcare. During your pet's annual exam, your veterinarian in Novato can check your dog for any signs of parasites and recommend parasite control measures or products that would be suitable for them based on your location, your dog's risk factors, health status and more.

Note: The advice provided in this post is intended for informational purposes and does not constitute medical advice regarding pets. For an accurate diagnosis of your pet's condition, please make an appointment with your vet.

Is it time for your dog's annual preventive care visit? Contact our Novato vets today to book an appointment for your pup. 

New Patients Welcome

Bel Marin Animal Hospital is accepting new patients! Our experienced vets are passionate about the health of Novato companion animals. Get in touch today to book your pet's first appointment.

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