Andrea Rosebrock 
I just received this email alert and wanted to pass the information along in the case that it may pertain to you. It is directly mainly at pet owners located in the Gulf region. If this is you, you may want to talk to your vet and have your dog tested for heartworm, just as a safety measure.
I want to share something with everyone, not to cause panic or anything, but because this is something everyone with dogs/who deals with dogs needs to know. Last month, one of my dogs, Rosey (small Beagle), tested positive for heartworm. I was absolutely floored. Of COURSE I have all my dogs on preventative. I am religious about it. How could Rosey have gotten heartworms???? The vet suggested that, because I was giving her the “0-to-25 pound” dosage (she is 25 pounds), that perhaps she should have been getting the “25-to-50 pound” dosage. Hmmm… ok.
Then he shared with me that there is a growing concern in the vet community that there is now a strain of heartworm in the Gulf region that has become resistant to Ivermectin. My heart sank. Really? He assured me they were questioning the makers of the preventatives…..
Well, yesterday, Satchmo, one of my Bassets, went for his annual…. And guess what…. he tested positive for heartworm. He is 58 pounds and takes the “50-to-100 pound” dose no under-dosing there!
My vet) and I talked for a long time. There is indeed apparently now a strain of heartworm that is resistant to Ivermectin, they are thinking. They suspect it is related to the effects of Katrina. She said more and more dogs in the Gulf area are testing positive…. Dogs who are ON preventative, regularly, religiously, like mine. I’m so upset, I can’t even think.
Now, it’s not every dog, of course. She said many are testing negative, as expected. But I know, in my house, 2 of 6 dogs have been infected, while on preventative.
I give Iverheart, which is the same as HeartGuard, and like HeartGuard, they have a guarantee that they will pay “reasonable” charges for treatment if a dog gets heartworm while taking their product. So I will pursue that. I just finished paying for Rosey’s hw treatment, but that’s a separate issue – cost.
The most most most distressing thing is that our dogs are not protected!
I would suggest that if you live in the Louisiana/Mississippi area, you get your dogs tested. And that the manufacturers of HeartGuard and Ivermectin be held to the task of finding out why their products are failing….. and what are they doing about it.
And for all the rescues? I have no idea what we are going to do in that situation. I know the no-kill shelter that I am associated with here in Lafayette houses over 70 dogs. All on Ivermectin.
IMPORTANT: just giving Ivermectin (preventative in some form) to treat heartworms, as some rescues do, will obviously not be an option anymore.
The preventative is not even PREVENTING; there is no way it will actually KILL heartworms. And until they figure out what’s going on…
Update: I did speak with the Ivahart people today. They want 2 years documentation that I’ve been giving Satchmo Ivahart. I told them they have to get that from my vet. She said she would call her. We’ll see… My vet had already placed a call to them, and the Ivahart lady was aware of that. I suggested she call my vet right away.
Oh, the Ivahart person acknowledged that they are aware of the problem, FOR OVER A YEAR!!!!
Who’s Saying What