I know most of you in California don't use heartworm prevention since the threat is normally so low. Something to discuss with your vets.
Rare Mosquitoes Threaten Dogs in L.A. County
KTLA News
7:11 AM PDT, May 12, 2010
WEST COVINA -- A sudden jump in the population of rare mosquitoes in the San Gabriel Valley could endanger dogs, according to health officials.
So far this season, 300 western tree hole mosquitoes have been trapped from Altadena to Claremont, compared to 60 in the previous 17 years, according to the San Gabriel Valley Mosquito and Vector Control District.
The rare mosquito is a frequent carrier of heartworm, which, without treatment, can be fatal to dogs, L.A. County health department Dr. Emily Beeler said.
Monthly treatments can avoid heartworms. Mosquito Threatens Dogs: Rare Mosquito Species Threatens Dogs in L.A. County - KTLA