What are aare you in?
Heartworm wasn't prevelrnt here either - then KAtrina happened and southern dogs (where heartworm is rampant) were transported all over the country with little to no vetting. My vets heartworm patients tripled.
And 2 years ago we adopted a HW Shiba from Ohio - once she was here who knows if she got bit by a mosquito or how many times or where that mosquito went.
All it takes is one HW dog to start the spread in your area.
I would do heartguard every 6 weeks for the wamrest months of the year at least. I say 6 weeks because it actually dows work for that long - the comapny jsut doesn't think pwoplw are smart enough to remember to admister it 6 weeks apart so they say the 1st of every month.
Oh and ttoally muzzle Beni at home happy muzzles has some very cute ones so they don't make people think you have a "bad dog". I would take the muzzle on and off at home randomly use it for a bit here and there so that he doesn't think vet time everythime he sees it at home.
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Alicia,Owned by 2 Shibas, Niko and Avari, 3 cats, Miss Kitty, Mr. Grobbles and Al E. Cat and 2 beautiful daughters, Gwen and Penelope