All About Heartworms
Heartworm is one of the most common internal parasites that may infect your beloved pet. Most animals are at risk even though the degree of risk varies between species and areas. The heartworm infestation may cause serious symptoms and even be fatal unless the animal is treated on time. Effective prevention methods are readily available.
Heartworm is an internal parasite. It is spread by mosquitoes. When a mosquito containing the larvae bites your pet, they will continue to grow and develop into adult worms. The adults inhabit the right chamber of the heart. That is why the parasite is called heartworm. Infestation can occur anytime anywhere.
What pets are at risk?
Most animals kept as pet’s may be infested. These include cats, dogs, ferrets and horses. Rabbits and guinea pigs are not susceptible to heartworm, however. Statistics show that dogs are the pets with highest risk of infestation. Male dogs are more than four times more likely to have worms in their heart compared to females. Canines kept outdoors are at higher risk as well. They are five times more likely to develop the disease.
Pets in warm coastal areas, slow river and moor areas are at higher risk of heartworm. These are areas where mosquitoes thrive and bite pets more often. Generally, other geographic and climatic traits may also make an area a high-risk one. That is why it is best to check with your vet how safe your town is.
L3 infective heartworm larvae enter your pet’s system via a mosquito bite. The larvae live underneath the skin. There they undergo two transformations. The transformation from L3 to L4 occurs between 1 and 12 days after infestation. The larvae remain in the L4 stage of development for 50 to 68 days. Then they molt into L5 life stage. At this stage, they are immature worms.
Immature worms find their way to the heart through a peripheral vain. Their final stops are the right chamber of the heart and the pulmonary arteries. The parasites develop into adult worms around 6 months after first entering the body. Adult worms are between 4 and 12 inches in length. They can live up to five years. In heavily infested pets, especially dogs, the number of worms in the heart may reach 250 or higher.
Adult worms thrive in the heart of the host. If male and female worms are present, they reproduce. Female worms give birth to microfilariae which are able to survive in the host for as long as three years. These cannot develop into adults unless they are transferred to a secondary host, a mosquito, through a bite. The microfilariae develop into L3 larvae for 10 to 17 days, depending on the climate.
The L3 larvae move to the mouth of the mosquito so they can be transferred to another animal. In this way, an infested pet can actually spread the disease to his/her neighbors without direct contact.
Heartworm Infestation Symptoms and Diagnosing
The initial symptoms of heartworm disease include tiring easily after exercise, overall exercise intolerance and soft but deep cough. If your pet seems lethargic and you notice him/her coughing, you should call the vet timely. As the disease develops, the symptoms worsen. More rapid breathing than normal and weight loss are common. Your pet may cough heavily after exercise even up to the point of fainting. The ribs become easy to see while the chest begins to bulge.
There are two main types of blood tests used for the diagnosis of heartworm disease. One of them is the heartworm antigen. It is designed to identify the presence of a specific adult female antigen. If only a few adult males are present the results may be inaccurate. That is why another blood test is used as well. The microfilarial concentration test allows for parasites present in the blood sample to be recognized when the sample is inspected under a microscope. A chest x-ray is the best test that will confirm the presence of heartworms in the heart.
The main treatment of the disease involves killing the adult worms and the microfilaria, if possible. This is done through the administration of medications. The most commonly used active ingredients in heartworm drugs are thiacetarsamide and melarsamine. Most types of medications contain arsenic. That is why toxic reactions are possible in treated animals. Both of the main active ingredients produce effective results, but it is best to consult your vet which would be better for your pet.
Surgical removal of the adult worms is the recommended option when the infested animals are heavily infested, critically ill and suffer from vena cava syndrome with increased risk of toxic reaction. Microfilariae are usually killed with the use of preventive medication after all adult worms have been removed. Your pet insurance provider will cover your pet if He or she was to contract heartworm, as it’s in the best interests of the animal to remove this parasite as soon as it is possible.
Heartworm prevention methods are highly effective and much cheaper to use compared to treatment. Taking basic measures to repel mosquitoes from your house and yard during the warm months is highly recommended. Consider using flea and tick control medication that protects your pet from mosquito bites. This kind of protection is not 100% guaranteed, but it is useful.
Administering medications that can kill the larvae at stage L3 and the immature worms at stage L4 is the most effective method for prevention. This is the most effective prevention option for dogs. Since cats are at lower risk, your vet may recommend that your feline pet is not given preventive medication.
Diethylcarbamazine is effective for killing L3 larvae while ivermectin, selamectin, and milbemycin are effective for killing both L3 and L4 parasites. As the larvae and immature worms never develop into adults your pet is perfectly well protected.
Most preventive medications are administered monthly during the high-risk seasons. In some areas, pets may require preventive drugs all year round. You should consult your vet about the best option for your pet as soon as you get him/her home. The veterinarian will give you advice on what drugs, if any, are useful for preventing heartworm in your pet and how they should be administered.
If your pet contracts heartworm it’s very important that you deal with this parasite as soon as you can before your pet get any other complications. Make sure you check your pet insurance policy to see if you are covered for heartworm. Most insurance providers offer this as standard, however check your policy to be safe in knowing your vet fees will be covered in the event of heartworms.