Heartworm (Dirofilaria immitis) is a fairly large worm, up to 14 inches long, that in adulthood lives in the heart and pulmonary arteries of an infected dog. Dogs acquire this infection through mosquito bites as mosquitoes readily pick up larval heartworms from infected dogs and carry them to new dogs. Some geographic areas have severe heartworm problems while other areas have virtually none.

In a normal dog, blood is pumped with ease through the arteries of the lung. With the arteries plugged with worms, the heart must pump harder against the pressure of the plugged arteries. This condition is called pulmonary hypertension and the right side of the heart must drastically increase its ability for the heart to work. If worms begin backing up into the heart, there will be less space in the pumping chamber for blood to be pumped. In order to meet the body’s oxygen demand, the heart must pump faster and stronger still. There may come a point when the heart simply is not strong enough.

Early after infection, many dogs feel normal and show no signs of illness. Eventually, however, dogs with heartworm disease will become sick. Their clinical signs can include coughing, exercise intolerance, difficulty breathing, and in progressed cases, congestive heart failure. Fortunately, heartworm disease is both treatable and preventable!

The first step in treatment is clearing the migrating immature worms. By addressing the migrating immature worms first, we minimize the number of adult worms we must kill in the second step. Fewer adult worms dying at once means less risk. Fortunately, the immature worms can all be killed by monthly heartworm preventive products (i.e. Sentinel®, Interceptor®, Heartgard®, etc.). The American Heartworm Society recommends 1 to 3 months of a preventive prior to treating the adult worms. The only product currently available for the treatment of adult heartworms is Immiticide®. Treatment can be done in two to three doses, depending on how severe the infection.

Heartworm testing and the use of heartworm preventative is mandatory to prevent infection in your dog.  Even if your dog stays in the house much of the time, a heartworm preventative is still important.  Considering the severe damage that heartworms can cause and that treatment of the disease is expensive, prevention of the disease with a single monthly tablet is a great deal.

Sentinel® is the preventative that the doctors at The Drake Center recommend. It is a once-monthly tablet that clears immature worms and will suppress the female worm’s ability to reproduce. It also provides a broad spectrum of parasite control (roundworms, hookworms, and whipworms) as well as prevents any fleas feeding on the dog from laying viable eggs.

Heartworm in Cats

Heartworm disease in cats is quite a bit different from dogs. The cat is not a natural host for the heartworm, which means the migrating larval heartworm is not likely to complete its life cycle. The cat’s immune system is extremely reactive against heartworms, and for this reason, it is virtually impossible to detect immature worms in an infected cat. (The cat’s immune system removes them too quickly.) Also, symptoms of infection tend to be more immune-related than heart-failure related, unlike dogs. Cats develop lung disease, complete with respiratory distress, and chronic coughing or vomiting. Feline heartworm disease is often misdiagnosed as feline asthma. Because cats are more resistant to infection and the prevalence is low in San Diego, the doctors at The Drake Center don’t routinely recommend a monthly preventative.

Since the major signs of disease in cats are due to inflammation and immune stimulation, a medication such as prednisone (steroid) can be used to control symptoms. In general, if the cat does not appear sick, the American Heartworm Society recommends attempting to wait out the worm’s 2 to 3 year life span and simply monitor chest radiographs every 6 months.

The same heartworm adulticide therapy used in dogs is best not used in cats as it is extremely dangerous to do so and is considered a last resort. The good news is that feline heartworm infection is preventable, with monthly preventatives such as Revolution® or Advantage Multi®.

On November 6, 2008, Governor Arnold Schwarzenegger called for an increase in the California state sales tax to address the multi-billion dollar deficit in the budget and proposed a sales tax on all veterinary services. This was part of a larger combination of program cuts and revenue increases to balance the state budget. This proposal would have added approximately 10% to the cost of veterinary care. 

The CVMA mobilized our 6,000 members and they answered. Thousands of letters were sent to legislators and the Governor’s office by CVMA members. In turn, they mobilized their clients and the opposition grew. Our voices were so loud that a special extension was added to the Governor’s budget voicemail line to handle the opposition to the veterinary tax. 

We are grateful to our members, their clients, and friends in industry, breeder groups and the animal welfare arena who assisted in this effort. We also thank our state legislators who recognized that this tax would ultimately harm the animals that we cherish and the safety of our food supply.

While this is a great accomplishment, there is still work to do as there may be budget revisions in the future. The CVMA will continue to monitor the special tax commission appointed by the Governor to restructure and modernize California’s tax system and any proposals that could affect the taxation of veterinary medicine in the future.

We are very pleased, however, that our voices have been heard and veterinary services will not be taxed in the 2009-2010 budget!

Ultrasound is a valuable diagnostic tool offered at the Drake Center. It gives a 3 dimensional, real-time image of internal organs. It provides different information than an x-ray and is often used in addition to x-rays to get the most information on what may be going on within a pet.

X-rays are great at high-lighting structures containing air (such as the lungs or gas in the intestines) and dense things (bone, bladder stones). However, x-rays have a difficult time penetrating fluid and give a more obscure or hazy picture if fluid is present. Ultrasound, on the other hand, is excellent at penetrating fluid at can evaluate some structures that are not visible on x-ray, such as lymph nodes, adrenal glands, pancreas, and gall bladder. X-rays can tell an overall organ’s size and location but Ultrasound can look within the organ for signs of a tumor, abscess, or abnormal vessels. Having an Ultrasound quickly available helps us rule out many disease processes and reach a diagnosis more quickly. It even allows us to perform Ultrasound-guided biopsies and aspirates which are extremely valuable in providing a specific diagnosis.

Ultrasonography provides you with more information to make educated decisions about the care of your pet. The Drake Center is committed to providing  you with the best diagnostic tools available so you can make informed choices about your pet’s care.