Ahhhh, summer. It’s time for pool days, barbecues, and bonfires. On the not-so-fun side, it’s also peak mosquito season. You may think that their perpetual fur coats would protect dogs and cats from these blood-sucking parasites, but mosquitoes are relentless and are easily able to find their way to your pet’s skin. Mosquitoes can pass a host of dangerous diseases along to our furry friends, including heartworm disease.


What is heartworm disease?

Heartworms are actual worms that can grow up to one foot in length while inhabiting the heart and lungs of a dog. When a mosquito bites a dog that is infected with heartworm disease, it picks up microscopic larval-stage worms (called microfilaria) along with the blood meal. When that mosquito bites its next victim, it passes some of these worms into its body. Over a period of six months, the larval worms make their way to the heart and lungs of the dog and develop into mature adults.

Even if a dog is infected with only a few worms, each adult female can produce many more larval worms. Those microfilaria mature to produce more worms, and the dog’s health slowly deteriorates as his heart and lungs are taken over by the spaghetti-like parasites.

Signs of heartworm disease in dogs

Unfortunately, many dogs infected with heartworms will show no signs until the disease is advanced. If a dog does show signs, they can include persistent coughing, decreased activity (lethargy), fatigue, decreased appetite, and weight loss.


Treating and preventing heartworm disease in dogs

Heartworm disease is a serious and life-threatening disease. The presence of the foreign worms in the dog’s body causes significant inflammation. As more worms accumulate, they eventually block blood flow and cause heart failure. Treatment is available but it is costly, and dogs with advanced infection still may not survive. Even if treatment is successful, dogs can be left with lasting heart and lung damage.

The good news is that this horrible disease is completely preventable with a simple, regular preventive medication. Given orally, the preventives are flavored like treats, so they’re easy to administer. In addition to monthly prevention, every dog should be tested for heartworm infection annually to confirm that they are heartworm-free.

Can cats get heartworm disease?

Wait a minute… we’ve only talked about dogs. What about cats? While the dog is considered a natural host for heartworms, cats are a “dead-end host.” In cats, the worms often do not live to maturity and cannot mate to produce offspring. Therefore, cats are only infected with the few worms that were passed by the mosquito bite, but this doesn’t mean that heartworm disease is not a serious problem for cats.


Signs of heartworm disease in cats

As heartworms develop in cats, they can cause severe respiratory inflammation. Cats may exhibit asthma-like symptoms (coughing, wheezing), vomiting, decreased appetite, and weight loss. Unfortunately, since cats are often masters at hiding illness, the first sign may be sudden collapse or sudden death.


Treating and preventing heartworm disease in cats

Because there is no treatment for feline heartworm disease, we will work to treat and manage an infected cat’s symptoms for the rest of his life. Fortunately, similar to dogs, cats can be protected from heartworm disease with a regular preventive medication.


Does my pet really need heartworm prevention?

You may be thinking that your dog or cat does not need heartworm prevention. There are a number of reasons pet owners may have this misconception. Here are the top three:

  1. “Fluffy never goes outside.” — Mosquitoes have a knack for finding their way indoors, and even indoor-only pets are at risk of being bitten.
  2. “Mosquitoes are only a concern during the hot summer months.” — Although activity can decrease during the cooler parts of the year, mosquitoes are active anytime temperatures remain above 50 degrees. For much of California, this includes the entire year. Therefore, your pet should be given a heartworm preventive every
  3. “I have never heard of pets in my area contracting heartworm disease.” — Heartworm disease has been reported in all 50 states (yes, even Alaska!). Reporting of the disease in central and northern California is moderately high, meaning that heartworm disease definitely affects our pets.


Have questions about heartworm disease and prevention? Call our office at 916-726-2334. Even if you haven’t used prevention in the past, that’s OK! It’s as simple as confirming that your pet is currently heartworm-free with a fast, in-office test, then starting the preventive medication. After, you’ll be able to sit back and relax knowing that your pet is protected.