HHHeartworm (Dirofilaria immitis) is a parasitic filarial worm that lives in the right side of the heart and adjacent blood vessels of infected dogs and (to a lesser extent) cats.
The disease is transmitted to mosquitoes and it is important to know that this parasite does occur in Singapore
The adult worms can live for several years in the host and can block and damage the heart and blood vessels going to the lungs.
When the adult worms mature at about 6 months old, they produce live offspring called microfilariae – these small wriggly worms can be seen in the blood of infected dogs under the microscope.
The microfilariae are then transmitted via mosquitoes to another dog where they mature and migrate to the heart.
Dogs that are infected with heartworm disease show signs such as weight loss, anorexia, coughing, breathing problems and exercise intolerance depending on the severity of the infection. If left untreated, they eventually develop congestive heart failure and die.
Heartworm disease is more of a problem in certain districts in Singapore
Dogs living in landed properties are also more at risk. This ties in with greater incidence of mosquitoes around these residences. Furthermore, these dogs are more likely to be living outdoors.
Fortunately, heartworm disease is preventable. It is administered either with monthly oral tablets / chewables, or monthly topical solutions, or with an annual injection. It is recommended that puppies start on heartworm prevention from 4-6 months of age. Dogs above 6 months old require a blood test to ensure that they are disease free prior to starting on prevention. It can be dangerous to give prevention to an already infected dog.
To test for heartworms, a small blood sample is collected and an ELISA test kit is performed for adult heartworms (above) and a small drop of blood is visualised under the microscope for juvenile heartworms (called microfilriae).
The dark blue spot on top is the control dot (to indicate that the test is performed correctly). The faint blue spot below on the right hand side indicates this dog is positive for adult heartworms.
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| Heartworm Test Kit |
The dark blue spot on top is the control dot (to indicate that the test is performed correctly). The faint blue spot below on the right hand side indicates this dog is positive for adult heartworms.
In the instance that heartworm disease is detected, your veterinarian will be able to discuss with you the treatment options.
To Note:
- Intestinal deworm tablets such as “all-wormers” do not prevent or treat heartworms.
- Mosquitoes are required to spread the heartworm disease; therefore the dog does
not need to be directly in contact with other dogs to be infected.
not need to be directly in contact with other dogs to be infected.
By Dr Ang Yilin for Mount Pleasant Animal Medical Centre
