CANINE HEARTWORM – final episode: Heartworm Control

Well, we have surely exhausted this topic, and perhaps even supersaturated you with facts about Canine (and Feline) Heartworm.
We have dealt with the transmission, life-cycle, symptoms, laboratory diagnosis and treatment. This last episode – the series’ finale, so to speak, will deal with the control of this dreaded disease.
Note that I referred to “control”, and not “prevention”; to try to totally prevent this disease is truly being ambitious. We will, instead, today offer suggestions which will go a long way in putting a halt to the possibility of your dog contracting the Heartworm Disease. In fact, even a truly effective control of Canine Heartworm is doubtful, for the simple reason that so many of our canine wards hardly ever (if at all) see the Veterinarian. Consequently, these untreated dogs could be harbouring the disease as a reservoir from which could originate the transmission to others.
Secondly, you will recall me writing that the lowly (but deadly) mosquito is the courier. The microscopic microfilariae (immature stages of the Heartworm) are in the mosquito’s mouth parts, and are deposited on the animal’s skin, from which they actively enter the animal, growing all the time until they reach the right-side heart chambers, where they become sexually mature and produce an abundance of new offspring (microfilariae).
Obviously, our first line of attack, within the context of control, would be to reduce the mosquito population in the areas surrounding the dog’s residence. This would not always be possible in parts of the country, where hygiene and sanitation of our living environment leave much to be desired. Also, I dare say that our Malaria Prevention Units, with their Vector (Mosquito) Control personnel, are doing as good a job as they can, in spite of being strapped for adequate cash, like so many other agencies. We cannot ever hope to have a mosquito-free Coast while untreated stagnant waters (the breeding grounds for mosquitoes) abound.
On top of all of this is the fact that mosquitoes are true survivors. They were around together with the dinosaurs, and over the millions of years, they have not even found it necessary to change their shape. Mosquitoes, we have been informed, can survive in high (ergo cold) altitudes as well as in tropical (hot) zones.
The point being made is that mosquito proliferation is difficult to control. Yet, we must try – not only because of human health problems (e.g., Malaria), but because of diseases like Canine and Feline Heartworm, which attack our companion wards. Of course, I have not even mentioned the nuisance factor in mosquitoes. We must use all the weapons at our disposal:-

i) Getting rid of all stagnant pools of water in the immediate environment of our habitations.
ii) Treating – e.g., with kerosene oil – areas where pools of water tend to accumulate.
iii) Fogging the area with chemicals that would kill mosquitoes and their immature forms.

The logic, of course, is that once the mosquitoes cannot reproduce, the specific mosquito-borne diseases cannot be transmitted.
The second method of control of Canine Heartworm is to ensure that the microfilariae (once they are in the dog’s body) do not reach adulthood, when they would be able to reproduce. This means that we must kill these immature forms when they are circulating in your pet. This can be done on a routine monthly basis.
Here we are lucky. The drug manufacturers have accommodated us by producing tablets, oral liquids and injectables containing an active microfilaricide (Ivermectin) which we had mentioned and discussed previously. They have even made different strengths of the medication according to the dog’s weight. This means that, after we have checked the blood on at least two occasions in the space of four weeks, and found that there are no immature states of the Heartworm circulating, we can begin to administer the medication once a month. Every month! This way, we can hope to achieve some great degree of prevention.
Lastly, mosquitoes tend to feed mostly in the late afternoon and during the evening. One could therefore keep the dogs in a mosquito-proof kennel during these periods, especially in those areas where we know the Canine Heartworm disease to be endemic.
So, enough is enough! By now you may not want to hear the word Heartworm. Sorry, but it was necessary. The last word: Listen for the soft, deep cough which may indicate a Canine Heartworm infection.