Heartworm Testing

If you're not using monthly heartworm preventives year round you should have your dog tested between now and April 15. This is the optimum time to test since there is a 6 month lag between the time heartworms are contracted from an infective mosquito to when the heartworm test can first detect adult worms in the heart. We are actually testing for last summer's infections. As soon as your dog tests negative you can begin the preventive again. You should give it monthly at least from April 15th through December 15th. Many people stop heartworm preventives after the first frost which is usually way before December 15. Since the preventive doesn't kill the immature heartworms until they have been in the body for 6-8 weeks stopping prior to then will allow the immature heartworms to enter the heart and mature into adults. The safest method of heartworm prevention is to just give it year round. It's only an additional 3 months and you get intestinal worm prevention which is present in most heartworm preventives year round. Another reason to give it year round: we've had mosquito hatches in the past during that 3 month period.
If you're using 12 month protection you can test your dog 1 year after the last heartworm test regardless of the time of year. Check with us if you missed any doses though.