I chatted with a vet recently who told me that Lupron depot 1 month, 3 month, and 4 months are essentially the same product, and how long it actually last depends on how fast your body absorbs it. this vet is extremely knowledgeable and one of the best vets all around. so say you use dose X for your ferret for a month. then the 3 month version is just using a dose of 3 X. the reason 3 months may not work as well is that the ferret may be absorbing the lupron faster, so X may last just under 3.5 weeks, and 3 X may last about 10 weeks, which means your ferret is short on the drug the couple of weeks before a re-check. we used to have a couple of ferrets on 3 months, but eventually switch to all 1 month because they do better with close monitoring. the main reason for using 3 or 4 month is probably costs. when we did use the 3 month a few years ago, the ferret was monitored on the 1 month dose for a year before switching over. Selina, Clef, Popcorn, Sorin, Mochi, Jolt & Cola [Posted in FML 5465]