[Elvismom]

Has anyone had any experience with drug resistant heartworms? It appears that Lexy may have them - we've sent samples out for testing - but we won't have results til next week.

I was hoping someone here might have some info.

 

[Mahna]

i have friend whose dog seems to have drug resistant hookworms, but not heartworms...so far they are just giving him higher doses of meds to see if it works, but he's been treated for them for about 3 months now.

 

[Mikey T]

Has anyone had any experience with drug resistant heartworms? It appears that Lexy may have them - we've sent samples out for testing - but we won't have results til next week.

I was hoping someone here might have some info.[/b]

It is unclear what life stage of the heartworm you are refering to but in any case it is highly unlikely to ocur

Is anthelmintic resistance a concern for heartworm control? What can we learn from the human filariasis control programs?
Available online 26 April 2005.

To date, there is no evidence of avermectin/milbemycin resistance in D. immitis, also a filarial nematode. Chemotherapy against trichostrongylids of animals, human filariae, and D. immitis, relies on avermectins or milbemycins. However, control involves targeting different stages or processes in the nematode life cycles, different control strategies, different proportions of the nematode population in refugia, and different drug dosage rates. Consideration of the proportion of the D. immitis population normally in refugia, the life cycle stage targeted, and the anthelmintic dosages used suggest that it is unlikely that significant avermectin/milbemycin resistance will be selected in D. immitis with current treatment strategies.[/b]

on adultcides
Dog Hearworm

The first step in ridding a dog of the parasites is to administer a chemical to kill the adult worms. Capasolate (Arsenamide, Thiacetarsamide), and Immiticide R (Melarsomine, dihyrdochloride) are arsenical compounds used to kill adult heartworms in both dogs and cats. These compounds are given as an intravenous injection and one or two doses are given each day for two days followed by restriction of physical activity for one to two months. As the worms die they are carried by the bloodstream to the lungs. One dog in twenty may be expected to die as a result of complications from this therapy. There are fewer complications with cats. Adult female worms and immature forms are somewhat resistant to Capasolate and, consequently, this drug may be less than 100 percent effective.[/b]

Howeever capasolate is not the standard treatment and has not been for quite a few years

<a href="http://www.heartwormsociety.org/article.asp?ID=9" target="_blank">2003 Guidelines for the Diagnosis, Prevention and Management of Heartworm
</a>

The organoarsenical adulticide, melarsomine, is less toxic and more effective than its predecessor, thiacetarsamide, which is no longer commercially available[/b]

keep in mind this is not the most recent quidlines but AHS no longer felt compled to mention capasolate in the 2005 guidlines http://www.heartwormsociety.org/article.asp?id=48[/url

 

[Mikey T]

i have friend whose dog seems to have drug resistant hookworms, but not heartworms...so far they are just giving him higher doses of meds to see if it works, but he's been treated for them for about 3 months now.[/b]

hookworms differ from hearworm in the regard to resistance

<a href="http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TD7-4M0S3DY-2&_user=10&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_version=1&_urlVersion=0&_userid=10&md5=864762a941ce859e70f7d71da2b31949" target="_blank">
High-level pyrantel resistance in the hookworm Ancylostoma caninum </a>

 

[Elvismom]

It is the microfilaria, not the adult worms, that are possibly resistent. She had to 2 shots for the adult worms, then a microfilaricide. AFter 2 weeks she still had microfilaria in her blood, so she got another dose of microfilaricide. 2 weeks later she still had the microfilaria. That was Friday and vetlady sent the sample out to be tested.

We have almost no hw in NM (although it is slowly moving into the state), but she has read recent literature about potential drug resistant hw.