[Shawna]

Hey Losul,

You may have already made your decision on what to do and what product to use but either way I think it is important for you to know the heartworm life cycle.

Microfilaraie circulating in the bloodstream, from my understanding, CAN NOT become adult worms without first going through L1 to L3 changes IN A mosquito. With this in mind, I don’t see how the worm burden can increase during these frigid winter months. Check with your vet to make sure about this but here’s some data.

FDA — “Microfilariae cannot become infective larvae without first passing through a mosquito. When the infected mosquito bites another dog, the mosquito spreads the infective larvae to the dog through the bite wound. In the newly infected dog, it takes between six and seven months for the infective larvae to mature into adult heartworms.” http://www.fda.gov/animalveterinary/resourcesforyou/animalhealthliteracy/ucm188470.htm

From what this and others are saying — Turbo has had this infection for at least six or seven months but maybe longer for there to be detectable L1 microfilariae in the blood.

American Heartworm Society — “Microfilariae cannot mature into adult heartworms without first passing through a mosquito.” http://www.heartwormsociety.org/pet-owner-resources/heartworm.html#lifecycle

Trifexis website — “Microfilariae are actually microscopic larvae. They live in the blood of most heartworm-infected dogs. Microfilariae are ingested by a mosquito that feeds on an infected animal, where they molt twice over a period of about 2 weeks and develop into infective larvae…. An infected dog will typically be carrying microfilariae within 6 to 7 months after first being infected by the initial mosquito bite. And the cycle continues.” http://www.trifexis.com/about-parasites/about-heartworms/heartworm-lifecycle.aspx

There hasn’t been enough time for the infection to have been caused by not giving the preventative in November and after — the infection had to have happened before that. Which also means that the heartguard you were using wasn’t working (unless you missed giving – which I doubt). I also thought I read that heartguard should not be divided into multiple doses as the medication is not uniform throughout the product. Someone please correct me if that is incorrect.

If the above mention of splitting is correct, you could have given one dose with medication in it. The very next day Turbo could have been bitten by a mosquito. The next month you could have given the non-medicated portion and then again when splitting the next month non-medicated could have been given. By the time the next dose carrying medication is given the larvae could have developed to L5 stage (young adult) where heartgard (and others) are ineffective. OR, the mosquito’s in your area are ivermectin resistant.

• This reply was modified 12 years, 1 month ago by Shawna.
• This reply was modified 12 years, 1 month ago by Shawna.