I too am interested in this. I'm not a vet but I have a whole team of stumped vets. My cat is 14 yrs old, spayed when she was 6 months old. No tumors, no masses, perfect blood work, perfect urinalysis, and has had urine culture, xrays, ultrasound. She's fine except she is suddenly in heat. She's more than likely responding to my BHRT but since that isn't going to stop, we need to find an answer here. Vets feel if it were a bit of ovary left from her spay, it would've shown up earlier than 13 1/2 yrs later.
ANYTHING will help! We haven't slept in a week, and neither has she, because of the howling. It's awful! Rescue Remedy helps for 30 minutes maybe. I've put Feliway electric atomizers throughout the house but it could take a week to a month to see if it has any sort of calming effect.
She's miserable, we're miserable, the other cat is miserable - no sleep for any of us. So this implant sounds interesting to me.