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Heartworm Disease in Arizona

Heartworm disease is a preventable, life-threatening disease spread through mosquitos.  It primarily affects dogs, although rarely cats can also be infected.  The disease is spread from dog to dog when a mosquito bites an infected dog and then bites a vulnerable dog. 


When the mosquito bites a vulnerable dog, the heartworm parasite enters the bloodstream and eventually migrates to the heart.  Once in the heart, the heartworm parasite causes damage to the heart and vessels in the lungs.  If left untreated, heartworm disease can lead to serious and life-threatening conditions such as pulmonary hypertension, heart enlargement, kidney disease, and eventually heart failure. 

Clinical signs of heartworm disease include:

  • Cough

  • Difficulty breathing

  • Weight loss

  • Ascites (fluid retention in abdomen)

  • Exercise intolerance

  • Weakness or fainting

Is heartworm disease in Arizona?

Heartworm disease is found in all 50 states, including Arizona.  Heartworms are spread through mosquitos, not dog-to-dog contact.  While Arizona does not have as many mosquitos as the southern and eastern US states, we still experience enough mosquitos for them to be a problem.  This is especially true during the monsoon season.  Veterinary clinics throughout Arizona routinely diagnose and treat heartworm disease in our canine patients.  This is why we recommend all dogs be given year-round prevention against heartworm disease. 

How do I prevent heartworm disease?

Thankfully, heartworm disease is easy to prevent in dogs.  It can be prevented through consistent, year-round parasite prevention such as Heartgard Plus or ProHeart.  These medications require a prescription from your veterinarian as well as annual heartworm testing.  Annual heartworm testing is required for all dogs before prescribing a prevention product in order to make certain your dog is not infected with heartworms. 

Heartgard Plus (ivermectin/pyrantel) is a beef-flavored chewable tablet for the prevention of heartworm disease and some intestinal parasites such as hookworms and roundworms.  The chewable is highly palatable and tolerated by most dogs.  Heartgard Plus must by given every month in order to prevent heartworm disease!  Even missing one dose can result in a heartworm infection. 

ProHeart (moxidectin) is a long acting heartworm prevention medication that is administered by a veterinarian.  ProHeart can be given in a 6-month or 12-month long lasting injectable product.  The advantage of ProHeart is the long-lasting protection without the risk of missing a monthly dose.  

How do you treat heartworm disease?

Preventing heartworm disease is much easier and cheaper compared to treating an infection.  If your pet is diagnosed with heartworm disease, your veterinarian will recommend advanced testing (labwork, chest x-rays, and etc.) to determine the severity of infection.  Treating heartworm disease involves months of strict kennel confinement, medications, and expensive injections in order to kill the adult heartworms.  Even after successful treatment, an infected dog may have long lasting effects from the disease. 

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