Heartworm testing is a big money maker for veterinarians. Since monthly preventives are virtually 100% effective and 18 months of one preventive (Heartguard which contains ivermectin) will actually cure an animal of the infection, yearly testing is very hard to justify. When your vet insists that testing is mandated before giving the preventitive, implying it would be harmful if given to an infected dog, remember this: The American Heartworm Society’s recommended TREATMENT for an infected dog is to give nothing but Heartguard monthly for the first six months. This sterilizes the female worms and they shrink in size which results in much less lung damage when they later die and deposit in the lungs. Then the Heartworm Society wants you to take the dog back to your vet so he/she can treat the animal but the Society reluctantly admits that 12 more months of monthly Heartguard will cure the animal. This is obviously much cheaper and safer than the vet treatment. I’m sure you vet will disagree!!
Also if it’s too cold for mosquitoes, there can be no danger of catching heartworm. Year around preventitive in areas of the country with seasons is a waste of your money. A new book “How to Afford Veterinary Care without Mortgaging the Kids” by Dr. Busby explains this and much more. Purchased locally, Amazon or Itasca Books. How to Afford Veterinary Care Without Mortgaging the Kids.