The lead physician who developed FeralStat passed away and it seems, since 2011, the product has not been available. No information about FeralStat is forthcoming and no one knows what happened to it.
Alternatively, people taking care of cats privately, in shelters or rescues are attempting to purchase the active ingredient in FeralStat which is Megestrol Acetate. The drug can only be sold with a veterinarian’s prescription being presented at a pharmacy.
A very small amount of the medication is necessary to act as a contraceptive – about 1/8 teaspoon of the liquid or 1/4 of a 20 mg. tablet per cat.
So far, Megestrol Acetate works well without any side effects. But check with your veterinarian as to dosage for multiple cats and drug availability.