Heartworm

Heartworm is a serious disease that can be fatal.  It usually affects dogs, and occurs more rarely in cats, foxes, wolves, coyotes, ferrets, sea lions and, in exceptional cases, even humans.  This disease is named heartworm because the parasite that causes the disease, in its fully matured and reproductive adult life cycle stage, resides mainly in the pulmonary artery of the host animal’s heart, where it can survive for many years.

Heartworm is a disease is caused by an infection of the parasite Dirofilaria immitis, that is initially transmitted through the bite of a mosquito.  This parasite goes though several life stages before it infects the animal.  The heartworm in the youngest stage called ‘microfilaria’ resembles microscopic worms, and survives in the bloodstream.  Once it is ingested by the sucking of the mosquito into the mosquito’s gut, it undergoes an intermediate stage of maturation and after 2 to 6 weeks the parasite then moves to the salivary glands of the mosquito and is transmitted to the animal through the mosquito’s bite.  The period of infection of your pet, when the heartworm fully matures from a larvae released in the blood into adult stage, and settles in its home in the heart of the animal, takes 6.5 to 7 months in dogs and is called the ‘prepatent period’.   When your pet becomes infected , the parasite worm continues to mature and grow and once it reaches the mating stage, the ‘patent stage,’ reproduces into thousands of microscopic ‘microfilarie’ in a continuous cycle.  This parasitic invasion causes devastating damage to the animal’s heart, pulmonary artery, and lungs.

Information on the Heartworm Life Cycle

It is very important to look for these common signs of illness in your pet, that are displayed only after the heartworms have fully matured and are causing organ damage:

1. weight loss
2. lethargy
3. reduced exercise tolerance
4. coughing

These are not all the possible signs of heartworm disease, and the majority of cases indicate that the signs of heartworm are not always evident.  The only way to ensure that your dog or cat does not have heartworm is to bring them to a veterinary clinic and have heartworm testing done on a regular basis.  If your pet remains untreated with a heartworm infection, they will eventually die from it, and even a late stage treatment may pose a risk and fail to save them.  The most effective defense for your pet against heartworm disease is the veterinarian’s prescription of prophylactic treatment that is administered on a monthly basis.  The preventive medications prescribed protect the dog or cat and other pets by preventing any heartworms that the pet has been infected with from reaching the last stages of maturation in their life in the heart. Some of these preventive treatments for heartworm also offer protection against parasites that attack the intestine and ticks and fleas.
Although cats are a less likely candidate for contracting heartworm disease, because they have higher resistance to it, they can also be a target.  To give your cat the greatest chance of protection from this parasite, it is strongly recommended to discuss the latest tests available for heartworm identification and prevention in cats.

Testing is Important  

Eliminating the possibility of your pet having contracted heartworm in the past, through regular heartworm testing, will ensure your pet has the best chance possible to fight this dangerous disease.  Current heartworm preventative treatments are very effective but must be administered carefully and medication doses cannot be missed so that the chance for infection does not happen.
Heartworm in combination with Wellness testing, is very valuable in determining your pet’s heath and for the prevention of diseases. Besides testing for heartworm disease and additional wellness tests, regular fecal exams will indicate your pet’s health. 

Heartworm Testing and Fecal Examinations

Fecal examinations provide the evidence of intestinal parasites if they are present in your pet’s system. Intestinal parasites pose a risk to the health of your pet and need to be addressed.  These parasites not only endanger the health and quality of life of your pet but also pose a threat to the pet’s human family.  Several types of intestinal parasites are ‘zoonotic,’ meaning they can be transmitted to humans.  The Companion Animal Parasite Council (CAPC) recommends that pet owners have their pets undergo regular check-ups with a veterinarian and have parasite preventative treatments that include the regular worming of dogs, and fecal exams done 1-4 times per year.  Fecal exam frequency is dependent on the age and lifestyle of your pet and their human family.    

The parasites that affect the intestines, are referred to as ‘internal gastrointestinal parasites,’ do the greatest extent of tissue and organ damage in their adult stage and are: roundworms, hookworms, and whipworms.  These worm parasites are usually not excreted in stools, and using stool alone without further testing procedures makes the identification of these parasites inconclusive.  The eggs of the parasites are present in the stool, but cannot be detected in their microscopic size by the naked eye.  Further laboratory testing using a process called ‘fecal flotations’ needs to be done.  This process involves the mixing of the collected stool sample with a special solution in a cylinder.  The solution acts to dislodge the eggs and make them float to the liquid’s surface where they collect on a microscopic slide that is positioned on the cylinder top.  The results of the test identify the presence of the parasite eggs and also other parasites such as giardia and coccidia that may be present.  Proper treatment can then be prescribed and your animal’s illness and suffering can be cured.  

Wellness Testing

Wellness testing involves the careful evaluation of an animal’s blood sample.  One of the times this is obtained is at the same time when collecting your pet’s heartworm sample.  From these tests, organ function can be evaluated and the animal’s red and white blood cell count and function can be studied to determine if any illnesses are present.  Indicators of disease are many and varied, and can be traced through the blood.  Abnormalities of kidney, liver, heart, thyroid and pancreatic function are several important organs that studied.  The blood test results that are gathered will remain in your pet's file to be used as a baseline for comparison studies with future wellness tests and blood work done during regular checkups and for the helping to tailor a treatment plan in the event of injury or illness.

Would you like more detailed information on Heartworm? Click on these links to reputable veterinary medical sources:
The Companion Animal Parasite Council (CAPC)
American Heartworm Society
American Animal Hospital Association (AAHA); Healthy Pet