Heartworm Awareness Month

Heartworm disease is transmitted by mosquitoes and can be deadly, if left untreated.  “Dogs get heartworms by being bitten by mosquitoes,” says Dr. Rhoades, Medical Director for the Pet Alliance of Greater Orlando. “Keeping dogs on a heartworm prevention is required year-round to keep them healthy here in Florida.”  Prescription heartworm prevention is available for dogs who have tested negative for the disease for about $10 a month.

 

What do heartworms do to a dog?

It takes about seven months, once a dog is bitten by an infected mosquito, for the larvae to mature into adult heartworms.  Adult heartworms can grow up to a foot long and can live for 5-7 years.  They can fill the heart chambers, lungs and clog major blood vessels leading from the heart.  Heartworms can cause difficulty in breathing and reduced blood flow to major organs of the body.  The heart, lungs, liver and kidneys can all be caused to malfunction by an infection of adult heartworms.

heartworm3The signs of heartworm disease depend on the number of adult worms present, the location of the worms, the length of time the worms have been in the dog and the degree of damage that has been sustained by the heart, lungs, liver and kidneys.

The most obvious clinical signs of heartworm disease are a soft, dry cough, shortness of breath, weakness, nervousness, listlessness and loss of stamina. All of these signs are most noticeable following exercise, when some dogs may even faint or become disoriented. Your veterinarian may notice abnormal lung and heart sounds when listening to the chest with a stethoscope. In advanced cases, congestive heart failure may be apparent and the abdomen and legs will swell from fluid accumulation. There may also be evidence of weight loss, poor condition and anemia. Severely infected dogs may die suddenly during exercise or excitement.

It usually takes time before the dog displays clear signs of infection. Consequently, the disease is diagnosed mainly in two to eight year old dogs. Unfortunately, by the time clinical signs are seen, the disease is usually well advanced.  This is why we cannot stress the importance of testing your dog annually and then keeping them current on heartworm preventative.

 

How is heartworm disease spread?

Since transmission requires the mosquito as an intermediate host, the disease is not spread directly from dog to dog. Spread of the disease coincides with mosquito season, which last year-round in Florida.

The mosquito usually bites the dog where the hair coat is thinnest. However, having long hair certainly does not prevent a dog from getting heartworms.

 

How is heartworm disease treated?

heartworm2The treatment consists of both oral and injectable drugs and takes approximately four months to complete.  Initially, thirty days of oral antibiotics (doxycycline) are prescribed followed by two sessions of injectable drugs a month apart.  It is critical to restrict exercise during this treatment period while the adult heartworms die and are reabsorbed by the body.  Your veterinarian will determine the specific treatment schedule according to your dog’s condition.

The adult worms die in a few days and start to decompose following the injectable phase of the treatment. As they break up, they are carried to the lungs, where they lodge in the small blood vessels and are eventually reabsorbed by the body. This can be a dangerous period so it is absolutely essential that the dog be kept as quiet as possible and is not allowed to exercise for one month following treatment. The first week after the injections is critical because this is when the worms are dying. A cough is noticeable for seven to eight weeks after treatment in many heavily infected dogs

 

What is the response to treatment and prognosis?

Dog owners are usually pleasantly surprised at the improvement in their dog following treatment for heartworms, especially if the dog had been demonstrating any clinical signs of heartworm disease. Many dogs display renewed vigor and vitality, improved appetite and weight gain.

 

How can I prevent my dog from getting heartworms?

You can prevent your dog from getting heartworms by using a heartworm preventive. When a dog has been successfully treated for heartworms, it is essential to maintain them on a heartworm prevention program to prevent future recurrence. With the safe and affordable heartworm preventives available today, no pet should ever have to endure this dreaded disease.