Shawna thanks much and I’ve been reading the prior links you provided also. I’m positive doxy is going to be a part of whatever treatment we go with. I’m getting that the doxy will cause the female worms to abort and expel their babies (larvae) well before the mama ever dies, and become sterile, the females shrink some, causing a little less congestion? It helps weaken the worms, shortens their life, lessens pathology, and disrupts transmission. When the mamas do die, they should be virtually empty of the larvae that is believed to cause much irritation and reactions in the system when the large worms die? I didn’t word that very well, I know, but does that sound somewhat right?
The slow kill ivermectin/doxy treatment. Does that require extra ivermectin treatments, I think I saw somewhere every 15 days. And also concerning would be repeated rounds of the doxy? too much antibiotic treatment concerns me also.
I read that in order to be antigen detectible that there has to be at least 6 to 9 mature worms and at least 3 of those must be female. But there may be more sensitive tests used currently according to the A.H.S.. I don’t know how many he could have at the upper end. And we know that if the microfilaria test is correct that there are both males and females. We are supposed to be getting another ice/snow storm tonight and through tommorrow, they’re saying the roads are extremely slick already, but if I can get out tommorrow, I’m going to take him to the Vetco clinic (at Petco) for another HW antigen check.
The vet said I could always later change HWP’s, and with only a 30 day gap but I don’t think he meant during treatment. I think it would concern me going from moxidectin to ivermectin. I researched this before, but just going off the top of my head for now. Ivermectin has a short half life, it seems maybe 6 or 8 hours or something like that. It’s rapidly metabolized by the liver, after a day it’s mostly gone, and after a couple of days it’s nearly completely gone.
The way I understand it, the topical moxidectin builds up gradually to levels before tapering off to more constant levels (3 to 4 months.) During that period and supposedly even on the first dose it goes to work on L3, L4, and even immature L5, and supposedly it works well on those, the proponents say better than the others, and with a narrower suceptibility gap. But evidently it isn’t so effective on microfilaria (L1) until it accumulates for some reason. It seems to me that if moxi takes that much time to build up, it would also take a long time to completely leave the system, so I am surmising that it would probably be fairly easy to switch from ivermectin to moxidectin, but maybe not vice versa, because, even after a month of nothing, I think there would still be substantial moxidectin in the system, and then to be adding something else (ivermectin).
AHS guidelines about seasonal preventative usage;
“To be maximally effective, heartworm prophylaxis should be given year-round, but if seasonal treatment is chosen, administration should begin at least one month prior to the anticipated start of heartworm transmission and should continue for at least 3 months after transmission typically ceases. The latter 3-month recommendation emanates from new knowledge regarding resistant strains, which showed that extended treatment after exposure is required to prevent infection. Current data demonstrate that not all compounds and formulations necessitate this extension.” ( they may be referring to
moxidectin here?)
I think Ivermectin will cause a very rapid die-off of L1 microfilaria which is not usually desired in cases where the L1 count is moderate or high, due to risk of severe reaction, so the slower kill off of L1 could be an advantage with moxi. I think I read somewhere that is actually the only one FDA approved as a microfilaricide.
A.H.S. guidelines;
” Topical moxidectin is now FDA-approved for use in heartworm-positive dogs to eliminate microfilariae. No adverse reactions due to high microfilarial counts were observed in the
laboratory or field studies conducted for approval of this label claim.”
also they say this about other combos with doxy may have similar results as the ivermectin/doxy combo. for weakening the adults, but only going by anecdotal reports;
“Select macrocyclic lactones coupled with doxycycline individually suppress embryogenesis
and weaken adult heartworms. As mentioned previously doxycycline reduces Wolbachia levels in all stages of heartworms. Studies have shown that administration of doxycycline in combination with ivermectin provided more rapid adulticidal activity than ivermectin alone as well as more efficiently reducing Wolbachia numbers more effectively than doxycycline alone. Anecdotal reports on other macrocyclic lactones with adulticidal properties suggest similar results but no confirmatory studies have been published.”
“In cases where arsenical therapy is not possible or is contraindicated, the use of a monthly heartworm preventive along with doxycycline at 10 mg/kg BID for a 4-week period might be considered. An antigen test should be performed every 6 months and the dog not considered cleared until two consecutive negative heartworm antigen tests have been obtained. If the dog is still antigen positive after one year, repeat the doxycycline therapy. Exercise should be rigidly restricted for the duration of the treatment process.”
Shawna, Dr. Garner is a big proponent of advantage multi, and he advocates and uses a similar protocol as what my vet is recommending (excepting all the prednisone), and also as the AHS guidelines. You can see my vets protocol in my initial post. I realize now, his was the HW surgery video I watched. I EMailed him with some questions, including one about using advantage multi/doxy in a slow kill, hopefully he will find time to reply. If you get a chance could you take a look. Maybe you can tell me your opinion about using multi/doxy in either the full 3 treatment immiticide plan or the slow kill possibilty using multi/doxy. As of now I’m leaning towards the fast kill, but at the very least I need to decide quickly which monocyclic lactone (moxidectin,ivermectin, or?) to get him on. Then I can decide more from there.
Heartworm Treatment Dogs
Thnx Shawna!
