Dog laying in the grass.

Heartworm disease is a serious problem for dogs and cats across the country, especially in California. Unfortunately, it is a disease that not many pet owners do not know enough about. Bayside Animal Hospital is excited to celebrate Heartworm Awareness Month with our readers and help animal lovers everywhere keep their pets safe from this dangerous disease.

What Is Heartworm?

As their name implies, heartworms are, in fact, worms. These worms can become up to a foot long, and reside in the heart, lungs, and nearby blood vessels. This serious parasitic infection mostly affects dogs, cats, and ferrets, but has also been found in other mammal species like coyotes and sea lions.

The natural host of heartworms, Dirofilaria immitis, are dog species. Being a natural host means that heartworms are able to complete their life cycle within this species; mating and producing young heartworms, called microfilaria.

Cats, on the other hand, are not natural hosts for heartworm. This means that they tend to have fewer worms when infected, but that the infection is less likely to be detected early. Cats are also more likely to have serious, life-threatening complications from heartworm infection. 

How Pets Get Heartworm

Some people are misinformed about how heartworm is transmitted and mistakenly think that good hygiene, a pristine yard, or limited contact with other animals will protect their pet.

Heartworms, however, are transmitted by mosquitoes. When an infected animal is bitten by a mosquito, microfilaria enter the mosquito digestive tract and mature into infective larva. In about 10-14 days, if that mosquito bites another pet, the larva can be transmitted into the new host’s bloodstream.

This means that unless we can eradicate mosquitoes from a pet’s environment entirely, heartworm disease is a risk even for indoor pets. In fact, Granite Bay is an area with a pretty dense incidence of heartworm disease

Once a pet has heartworms in its body, the worms take about six months to mature, after which time they can reproduce. An adult worm can thrive in their host for up to seven years in dogs and three in cats—causing irreversible damage along the way. 

Signs of Heartworm

Heartworm disease can be a silent disease—until it’s not. Because it takes about six months for the worms to mature after an infective bite, it is very unusual to have any symptoms at all during this time. In fact, your dog’s routine heartworm test can’t even detect an infection during this time frame.

As heartworm disease progresses, though, symptoms may begin to occur. The longer the infection is present, the more likely you are to see symptoms. Signs of heartworm disease can include:

  • Mild coughing
  • Fatigue
  • Decreased willingness to exercise
  • Decreased appetite
  • Weight loss
  • Heart failure in advanced stages (fluid in chest, abdomen)
  • Sudden collapse
  • Open mouth breathing in cats
  • Sudden death (especially in cats)

What You Can Do 

Heartworm disease can be devastating. Thankfully, though, we are better than ever at knowing how to prevent heartworm. When we take proper precautions, we are very good at nearly eliminating the risk that you will ever need to deal with heartworm disease.

All puppies and kittens should start on heartworm prevention right away. There are safe and effective options available for pets of almost any age or weight. Heartworm preventions are not 100% effective, but they are darn close when given year round.

Because heartworm prevention is not quite 100% effective, though, and because we are human and sometimes make mistakes, annual testing for heartworm infection is very important. This helps us to catch any lapse in protection early, before permanent damage to the cardiovascular system occurs.

Heartworm testing should be done:

  • Six months from when your puppy starts heartworm prevention
  • Before starting heartworm prevention (if your pet is over seven months of age)
  • Annually for adult dogs as part of their wellness care
  • Six months after any known missed dose of prevention

It is a little harder to detect heartworm disease in cats. They should be tested before starting prevention and subsequently based on risk.

In dogs, we can treat heartworms, but it is an expensive road that is not a pleasant one for you or your pet. In cats, there is currently no effective treatment for heartworm disease. A solid prevention plan is our best defense. 

If you have questions or concerns about the disease or how to best protect your pet, don’t hesitate to contact us. We are always happy to help keep our pet patients healthy.