Hi losul,
First I’m so sorry for what you and your dog are going through. I myself have nightmares that I get that dreaded call in which I’m told my dog has heartworms. I know that giving less of the pill and less frequently than recommended is likely playing heavily on your mind. In actuality we don’t know what role that played as sometimes dogs on full prevention protocols come up positive too.
I’m sure this is scarey. I’ll try an answer your questions to the best of my ability.
Do you need a second opinion? If you want to look further, have a different type of test done vs a different vet who may be using the same brand test. There can be false positives on a heartworm test, but they are rare.
The fact that they saw microfilaria kinda clinches the diagnosis. There are other microfilaria that can be seen in blood, Dipetalonema comes to mind and a parasitologist can likely identify them for you. The sample may need to be sent to a university vet school. But really the chance you have both a false positive and a different type of microfilaria seems unlikely …I think you would be grasping at straws …
Should you consider slow kill? I’ll give you my opinion for what it is worth, I wouldn’t. I can’t put my hand on it at this moment. Will look for it if you want but as I remember in dogs treated with slow kill considerable ongoing lung damage occurred UNLESS the dogs were on complete exercise restriction for the entire duration. Your dog is young, I’m guessing active, and would be difficult to keep continually crated for nearly a year plus(?) of his life. There also is some speculation that slow kill may be contributing to resistance. Unless your dog is clear of microfilaria during a slow kill treatment ( meaning your dog has microfilaria because of your dosing and not strain) your dog will be infecting others with a resistant strain and spreading resistance.
Should you use moxidectin? So far as I know of only one study that compared efficacy head to head and moxidectin was more effective when given as a single dose. Time will tell if that holds: one study one strain. The moxidectin treated dogs didn’t develop heartworm with only one dose post exposure whereas dogs given 1 dose ivermectin or milbemycin did develop worms. Dogs given 3 monthly doses of milbemycin post exposure were also clear. As I recall this test was done with a strain thought to have resistance.
Moxidectin is also the drug in Pro Heart injections. Is a continuous yet decreasing amount of moxidectin as effective as monthly peak doses? I don’t have any answers for you, I think though it has failed whereas the monthly topical has not due to higher blood concentrations with monthly pulse doses.
I’ve noted on Trifexis (milbemycin) commercials it states to give for 3 months post exposure whereas Sentinal Spectum (milbemycin) has upped that to 6 monthly doses post exposure. For now my dogs get milbemycin, same day each month year round. If I lived in heartworm land… southern states where resistance is being seen I’d choose moxidectin. Likely if my vet was saying moxidectin topical I’d go with it trusting that he/she understands the local strains. I don’t mess around with heartworm prevention.
The preventatives I can think of are ivermectin ( heartgard and others), selamectin( Revolution) milbemycin( sentinal, trifexis,) moxidectin( advantage multi, proheart) diethylcarbamazine (daily still available???)
Should you vaccinate? This is beyond my ability to answer. I think your vet is the best person to answer this one.
Trembling/ fearful…. two things come to mind: pain and fear unrelated to pain. Fears can be to unusual scents, sounds (electrical equipment, ultrasonic, rodents etc ) Pain… any lip licking swallowing drooling that might help you pinpoint it?
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Again I’m so sorry you are going through this…your vet is the best one to help you through this. The American Heartworm Society guidelines are written as they are for a reason…. If it was me I’d make use of them: 3 injections and doxy. Best of luck
