Heartworm In Dogs: What It Is And How To Prevent It

By February 17, 2020 Uncategorized

Heartworm In Dogs: What It Is And How To Prevent It | Bickford Park Animal Hospital | Toronto Veterinary Clinic & Pet Care

One of the most well-known diseases that affects dogs today is heartworm.

Heartworm disease is a potentially fatal parasite, specifically caused by the organism Dirofilaria immitis.

Thankfully, there are many preventative treatment options for you and your pet.

Ask your veterinarian today about heartworm treatments for dogs and how they can help you protect your pup from contracting this pesky parasite.

But what is heartworm disease, what are the signs and symptoms, and what does treatment look like?

Let’s dive into the details of what every pet owner should know about heartworm.

What Is Heartworm?

Heartworm is a disease that occurs after your pet has been infected with Dirofilaria immitis, an organism — specifically, a nematode — known as roundworm.

The severity of your dog’s illness will vary depending on how many worms are present, the length of infection, and the response of your dog’s body.

These worms are spread through bites by mosquitoes carrying heartworm larvae, which gradually travel to your dog’s heart and lungs.

After travelling through your dog’s body (which takes around 6 months), the worms will grow and reproduce, releasing their young into your dog’s bloodstream.

These immature heartworms, or microfilariae, can be passed from dog to dog via mosquito bite, spreading the disease.

Heartworm has been diagnosed in various climates all across the world, but it is prevalent in subtropical and tropical areas.

This disease can range in severity, which we divide into four classes.

Each class has slightly different symptoms.

Class I

Class I is the least severe of the four classes of heartworm disease.

Dogs with Class I heartworm often do not display any symptoms at all, other than an occasional cough.

Class II

The symptoms of Class II heartworm are mild, but more noticeable than the previous class, including coughing and exercise intolerance.

Class III

With Class III heartworm comes a general degradation of body condition.

This includes weight and muscle loss, extreme exercise intolerance, dry or greasy hair, difficulty breathing, and a distended stomach/the appearance of a potbelly (due to fluid accumulation as a result of heart failure).

Class IV

Dogs with class IV heartworm have so many worms in their heart that the flow of blood is obstructed.

This is known as caval syndrome, and it is a sign that heartworm disease has progressed too far to treat.

What Causes Heartworm In Dogs?

Heartworm disease is one of the many diseases transmitted by mosquito bite.

Not just an itchy pest, mosquitoes carry microfilariae (heartworm larvae) that mature inside the body of the insect.

They can bite an infected animal and subsequently transmit the disease from dog to dog.

Symptoms Of Heartworm

As mentioned in the class sections above, there are varying symptoms that range from coughing and lack of appetite to exercise intolerance, fatigue, and coat condition.

If you suspect your dog may have heartworm, it’s best to visit your veterinarian immediately to run a quick blood test.

Heartworm blood tests are performed regularly as a preventative measure for pups who are on preventative heartworm treatments.

Once a positive blood test has been performed, additional tests will be needed to support the initial diagnosis, such as a blood chemistry panel, urinalysis, chest X-rays, and a blood cell count.

learn all about heartworm in dogs | Bickford Park Animal Hospital | Toronto Veterinary Clinic & Pet Care

Risk Factors For Heartworm

There are three major risk factors that affect your dog’s likelihood of contracting heartworm disease, although preventative measures should be taken no matter what.

The first is living in an endemic region, where the disease is prevalent.

Tropical and subtropical climates are especially high risk areas.

The second big risk factor is exposure to mosquitoes, since they are the only way your dog can contract the disease.

If you live in an area where mosquitoes are common pests, heartworm prevention should be at the top of your list.

Thirdly, the most important risk factor is a lack of preventative heartworm medication and care.

Treating your dog to avoid ever contracting heartworm is a simple process every dog owner should do.

Heartworm disease can be difficult to catch until it’s too late to treat, and it’s much easier on you and your furry friend to make sure you never have to worry.

Treatment For Heartworm In Dogs

The treatment and prognosis for dogs with heartworm disease depends entirely on the class, or severity, of the disease.

For dogs who have received some heartworm treatment for mild to moderate cases, the prognosis is often good.

This treatment involves multiple medications, including three injections to kill the adult heartworms, prednisone and doxycycline, anti-inflammatory meditation, and preventative medication to prevent any further infection.

Oxygen therapy is also sometimes utilized as part of this treatment.

Surgery is sometimes necessary for particularly bad cases, to remove the larger worms from the heart and blood vessels within the lungs.

Surgery always comes with risks though, for dogs, people, or anyone else, so it’s best to take preventative measures instead.

Exercise restriction is also a key part of heartworm treatment and is absolutely required during the entire process, which usually takes around 9 months.

It’s at this post-treatment point that your vet will start testing to see if your dog tests negative for heartworms.

Pain and anti-nausea medication may help your dog feel more comfortable during treatment.

If left untreated, most cases of heartworm are eventually fatal.

Preventing Heartworm

The number one step you should take as soon as you add a dog to your family is to speak to your vet about monthly heartworm medicine.

Before prescribing this medication, your vet will test your pup for worms just to be sure.

There are many different kinds of preventative heartworm medicine that are extremely effective and safe.

To learn more about your options, talk to your veterinarian.

Unfortunately, and like most medications, these meds are not 100% effective (especially if you miss a dose or if a dose was given late).

Routine heartworm screening is necessary as a preventative measure, to ensure your dog is clean of worms — and if they do have worms, it’s extremely important to catch them early.

It’s not only more cost-effective to prevent rather than treat heartworm disease, but we both know it’s about more than just the cost.

The best course of action for your dog’s health is to protect them against ever contracting heartworm.

Book An Appointment At Bickford Park Animal Hospital

If you have any questions about heartworm disease and how you can prevent it, we can help.

Book an appointment with us at Bickford Park Animal Hospital.

We understand that your dog is a member of your family and should be treated as such.

Heartworm disease is easily preventable, with care and energy from both you and your veterinary care team.

We would love to get to know you and your dog, and help you develop a preventative treatment plan that works for you and your family.

Call us at Bickford Park Animal Hospital today.

In yours and your pet’s health,

Dr. Helen Foster, DVM
Bickford Park Animal Hospital
807 Bloor St W,
Toronto, ON M6G 1L8


Bickford Park Animal Hospital is a veterinary clinic in Toronto, located across from Christie Pits park, committed to the highest level of caring and treatment for cats and dogs.