Good afternoon, I´m a new graduate in vet from spain, I know this web for a lot of time but I have never taken part here. Well, now I´m working I have found some doubts about the luteolityc drugs. Where I usually did practices, we used luprostiol (prosolvin) at a dosage of 7,5mg IM; but the place where I am right now its easier to find dalmacin (cloprostenol) and dinoprost. And I find a lot of differents dosages for, also different for the dosage for lutalyse i find here. Please can you tell me the dosage and way of administration you use.
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In North America, LutalyseŽ (dinoprost tromethamine) is packaged at a concentration of 5 mg/ml. The dosage recommendation is "a single intramuscular injection of 1 mg per 100 lbs (45.5 kg) body weight, which is usually 1 to 2 ml" (per the package insert). Note that those instructions are from a package insert for the product in the USA. Exactly the same product in Canada is licensed for sub-cutaneous use only.
Having said the above, it should be noted that those instruction are provided by the manufacturer, who is restricted to providing dosage recommendations based upon the FDA evaluation. They are not legally permitted to vary that recommendation unless more FDA-based testing is performed. There have been several pieces of peer-reviewed research presented (if I remember correctly, Nie et. al. in 2002 and then Newcombe subsequently) that have demonstrated admirably that considerably lower doses can be used with the same luteolytic result, but avoiding the unpleasant side-effects often seen such as sweating and cramping. That research suggests that one-tenth of the "standard" dose given on two consecutive days will have the same luteolytic result in the same time frame (estrus onset in 3-5 days), so one would give 0.1 - 0.2 ml per day for two days.
Similar research has been performed with Cloprostenol ("Estrumate"), but the interesting thing is that with Cloprostenol - which is synthetic and has a longer half-life - a single one-tenth dose is adequate (i.e. not 2 days in a row).
We ourselves typically use Lutalyse at the 0.2 ml dose two days in a row, intramuscularly. It is cheaper than Estrumate, and it is not a problem for us to dose twice. If one is providing the service for a farm-call client however, one may wish to use a single one-tenth dose of Estrumate, thereby not requiring a return for the second dose, or the leaving of a dose for the client to administer.
One other useful adjunct of using the low-dose treatment (other than the lack of unpleasant side-effects) is that because it is such a low volume, one can use a human insulin syringe. Not only do these have a very small needle (which means that most mares hardly even notice it) but they are also cheaper. Incidentally, the same thing applies when using the oxytocin protocol during breeding.
Bear in mind that a fully functional CL must be present, in the absence of large (>2cm) follicles in order for there to be a predictable timing of return to estrus, otherwise you may end up asking the proverbial question why didn't the Lutalyse work?!!
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