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How to Prevent Parasites in Dogs

Parasites pose a very real risk to the overall health and longevity of your pet, but preventing parasites has never been easier. In today's post, our Seymour vets discuss the ways parasites affect pet health and how parasites are prevented.

What is a Parasite?

A parasite is an organism that lives on or in your pet and then feeds on him or her to survive. Parasites can deplete your pet's vital nutrients, cause irreversible organ damage, and, in some cases, cause painful skin conditions or infections. So, which parasites should you be concerned about? Every geographical location has its own set of problematic parasites, so your vet will be able to tell you which parasites are common in your area. Having said that, there are a number of parasites that are commonly found in pets across North America.

Types of Parasites

Parasites are defined as organisms that live inside or on another organism - known as the host - and feed themselves off the host, often causing the host to experience a range of health issues.

Parasites fall into two main categories, those that are external (live on your pet's skin) and those that are internal and make their home within your pet's body and vital organs.

Parasite Control for Dogs

When it comes to parasite control in dogs, most vets agree that parasites are far easier and often cheaper to prevent than to treat once a pet has been infected. Preventing parasites also protects your pet against having to deal with the uncomfortable and sometimes deadly health effects of parasites. When it comes to heartworm in particular, prevention is considered to be the best possible way to save your dog or cat's life (see more information on heartworm below)!

Below are some of the most common parasites seen in dogs and cats, the conditions caused by these parasites, and what you can do to protect your pet.

External Parasites Commonly Seen On U.S Pets

There are a number of different parasites that can make their home on the skin or in the fur of your dog or cat. Fleas and ticks are two of the most common.


Fleas are external parasites that rely on a host animal, in this case, your dog, for survival. Once these tiny parasites have established themselves on your pet, they will multiply at an alarming rate. According to some estimates, for every adult flea found on your pet, there could be 100 or more immature fleas hiding throughout their coat. Not only that, but if your pet has fleas, these parasites are likely to infiltrate your home, hiding in carpets and soft furnishings.

Many dogs and cats are allergic to the proteins left behind by flea bites, causing the bite area to become unbearably itchy. When this occurs, pets frequently scratch and groom themselves excessively, resulting in raw damaged patches of skin, fur loss, and, in some cases, infections. Fleas pose an additional risk in that infected fleas can transmit tapeworms to your pet.


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

Ticks are extremely common all over the world, and many different species can be found in North America. Each type of tick poses serious health risks to both pets and humans. Tick saliva contains germs and bacteria that can be passed on to the animals and humans they prey on. These bacteria can cause Rocky Mountain spotted fever, Canine Bartonellosis, Anaplasmosis, Ehrlichiosis, alpha-gal allergy, or Lyme disease in the host.

Internal Parasites Seen in U.S Dogs & Cats

There is also a variety of internal parasites that can threaten the health of your pet and (in some cases) your family. 


Roundworms are common parasites in dogs and cats. They are large roundworms that live in the intestines and cause ascariasis, as the name implies. Roundworms are typically transmitted to kittens and puppies through nursing and can be contracted by eating the larvae found in the feces of other infected animals. Roundworms are zoonotic parasites, which means they can infect humans as well.

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 or cat's stool or vomit. Since roundworm infection symptoms aren't always easy to spot, it is important to keep 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 small intestine walls. Dipylidium canine species infect cats and dogs the most frequently, but several types are known to infect pets. Most pets become infected by swallowing a flea that has been infected with the tapeworm, which can happen while grooming or as a reaction to flea bites.


    Heartworms, also known as Dirofilaria immitis, are protozoan parasites that live in dogs' and cats' hearts, lungs, and surrounding blood vessels. Cats are more resistant to heartworm infection than dogs, but infection can still occur. This disease is spread by infected mosquito bites, when eggs enter your pet's bloodstream; the larvae travel through the bloodstream for several months before settling in the heart and pulmonary arteries.

    Heartworm infections can go undetected for months until the condition progresses and damage to the pet's internal organs begins. Heartworm disease treatment is available, but it is toxic to pets and can be very expensive. As a result, many pet parents are forced to make the heartbreaking decision to euthanize beloved pets diagnosed with heartworm disease.

    Parasite Prevention Made Easy

    As you can see, parasites pose a very real threat to the overall health and longevity of your pet, but in many cases, parasite prevention is both easy and affordable. Not only that, many parasite prevention medications available from your vet protect your dog against multiple parasites in just a single monthly dose.

    By bringing your dog to the vet once or twice a year for fecal testing and routine exams, as well as keeping your pet on appropriate parasite prevention, you are helping to safeguard your beloved dog against the negative impact of common parasites.

    To find out more about the parasites in your area that could negatively impact your pet's health, speak to your vet. Your veterinary professional understands the risk level of various parasites in your geographical area and can assess your pet's risk based on their lifestyle and other factors.

    Preventing Tick-Borne Diseases

    However, no medication is 100% effective against ticks. To help protect your dog from tick-borne diseases, use a tick prevention medication on your pet whenever ticks are active in your area, and check your animal's skin on a regular basis. Ticks are typically dark brown or black in color and can resemble a dark mole or bump on your pet's skin. Ticks must be removed correctly and as soon as possible to avoid infection. Bring your pet to the vet to have ticks safely removed and to learn how to remove ticks from your pet in the future.

    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.

    Want to find out about parasites and how to protect your pet? Contact Seymour Veterinary Hospital today to book an appointment with one of our vets.

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