You have a few options. One you could apply to some of the following organizations who might help finance your dog's treatment.
Veterinary Bill Assistance Programs:
1. The Big Hearts Fund: http://bigheartsfund.org/
2. Cats in Crisis: http://www.catsincrisis.org/
3. Diabetic Cats In Need: http://fdmb-cin.blogspot.com/
4. The Dog And Cat Cancer Fund: http://www.dccfund.org/
5. Frankie's Friends: http://www.frankiesfriends.com/
6. Handicapped Pets Foundation: http://hpets.org/
9. The Mosby Foundation: http://themosbyfoundation.org/
10. The Onyx and Breezy Foundation: http://www.onyxandbreezy.org/
11. Paws 4 A Cure: http://www.paws4acure.org/
12. The Pet Fund: http://thepetfund.com/
13. Pets-DC: http://www.petsdc.org/
14. Shakespeare Animal Fund: http://www.shakespeareanimalfund.org/
This site may have additional resources as well.
However, it is not unusual for people not to be able to afford expensive heartworm treatments. In that case an owner may elect a slower kill method. With this methd you would need to be giving the dog monthly heartworm preventative and usually the vet will also prescribe an antibiotic such as doxycycline for a month or so. Your vet will periodically retest for heartworms and is likely to prescribe antibiotics as well. This method is often used on dogs who have health issues which would make them poor candidates for traditional treatment. It does not kill the adults but does kill any larva produced so once the adults dies off, the dog no longer has heartworms. heartworms can live a long time even up to 7 years. The sooner you start preventative, the better since any that mature into adults will take a long time to die off naturally.
you can read more on heartworms here:
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