I just read an article published by the Australian Veterinary Association that said that the American Heartworm Association argues against the use of ‘slow kill’ in an effort to prevent population drug resistance to the macrocyclic lactones (ivermectin, moxydectin) that are used in this approach. In other words, not on the grounds of treatment efficiency.
The article, by Mark Rishniw:
Queensland News March 2015 - Heartworm Disease – dilemmas, dramas and dogma - Mark Rishniw | Australian Veterinary Association
The relevant paragraph:
“
The American Heartworm Society (AHS) and Companion Animal Parasite Council (CAPC) are advising strongly against the slow-kill protocol. Should I listen to them?
The argument proposed by AHS and CAPC against slow-kill (aka trickle-kill) protocols is that microfilariae produced by the adults in these dogs are exposed to the same sorts of selection pressures as described in the experiment above – that it leads to a selection of microfilariae with a resistant genotype. These microfilariae can then mature in mosquitoes to L3 larvae that are able to withstand preventative macrocyclic lactone administration, leading to adult patent infections in the face of preventative administration (“loss of efficacy”). With sufficient spread of these resistant genotypes through the population, widespread loss-of-efficacy issues arise. HOWEVER, all the studies performed to date have administered preventative doses of ivermectin alone.”
And I noticed also that the American Heartworm Association is sponsored by Zoetis, which is the US distributor for melarsomine.
Also....When there are a number of treatment options, as there are here, it usually means that there is no standout one that is obviously much better than the rest.
So, I wouldn’t rush to the conclusion that your vet hasn’t chosen the best treatment for Carbón.