Heartworm infection in dogs is caused by Dirofilaria immitis, a thread-like worm that is transmitted by mosquitoes while they feed on the animal. The adult worms generally migrate to the heart, blood vessels, and lungs where they mature and reproduce. The eggs produced by these heartworms – microfilaria, then traverse the bloodstream. It almost takes 6-7 months for the microorganism to mature and reproduce.
Types Of Heartworm Diseases In Dogs And Symptoms
Heartworms disease is generally of type 1 and type 2, type 3 and 4 classes. The type 1 is asymptomatic and thus produce no obvious symptoms through which the condition cannot be detected. Whereas, Type 2, 3 and 4 heartworm disease does show symptoms which typically include:
- A cough
- Lethargy and deteriorating physical tolerance of the body
- Nose bleeding
- Shortness of breath
- Weight loss
- Bulging appearance
- Lung dysfunction
- Heart attack
Caval syndrome or Type 4 heartworm disease is extremely fatal where the microfilariae accumulate in the heart and block the arteries and thus prevent blood flow. This blockage eventually leads to heart attack.
Lifecycle of Heartworms
It takes almost four stages for heartworms to mature and transform into adults.
- The first two stages of his lifecycle are completed in the mosquito. As the mosquito takes the blood from an infected animal, the microfilariae are transferred into its body.
- Virtually, they take 2 weeks to transform into larvae which then migrate into the salivary glands of the mosquito.
- Now, these larvae are transmitted to your dog as and when the infected mosquito takes blood-
- The larvae then start maturing into the juvenile worms which migrate themselves into different body tissues, lungs and
- It takes almost 70-90 days for the juvenile forms to mature into adult heartworms once they reach the heart.
- These adult worms then attach themselves to the heart and lung linings in large numbers restricting the blood to circulate properly through ventricles.
- This condition causes heart dysfunction, lungs failure and in advanced stages leads to heart attack. While still attached to the tissues, they reproduce hundreds of microfilariae which enter the bloodstream and repeat the lifecycle.
Adult heartworms can stay inside the host undetected for even up to 5 years.
A blood sample of the infected dog is collected for the detection of adult heartworms, microfilariae and the antigens produced by them. ELISA test, SNAP test, antigen test are some of the common diagnostic procedures conducted for discerning the severity levels of the disease.
Complete blood count (CBC) and electrolyte test are performed to check the functioning of the liver and kidney. Radiographs reveal any swelling or enlargement of heart or its arteries. Electrocardiogram(ECG) may also be recommended by the vet to check for the proper functioning of the heart.
Treatment And Prevention
If the dog is diagnosed with the presence of heartworm and increased level of severity, specific drugs formulated to kill adult heartworms are injected by the vet. Most commonly these injections are continued for a month to eliminate the heartworms completely from the dog.
If the region you stay in has high mosquito population, it is recommended to put your pet on preventives.These preventative like Advantage multi, Interceptor, Revolution for dogs, and RSPCA monthly heartworm tablets kill the microfilariae that eventually transform into adult heartworms.Thus, in short, these products kill the very origin of infection. So isn’t it wise enough to safeguard your dog in advance than waiting for the heartworms to do the damage?
Heartworm is a very serious disease which may threaten your pet’s life. Therefore, it is important that you stay aware of the causes and treatment. Eliminating mosquitoes from your surroundings should definitely be your first priority and administering the preventives to your pet, the second. So, get on your toes and proof your pet from heartworms now.
David joined CanadaVetCare in 2013 as a product analyst and veterinary assistant. Being a passionate pet lover and keen animal health researcher, David had always found ways and solutions to help pet parents to improve their pets’ health. He is always happy to answer pet health-related queries and recommending pet parents for the right pet product for their furry companions.