There have been some contraceptive pills for cats available in the past but as I understand it, they produce side effects that were unwelcome and/or they are not a hundred percent effective which is why people go for the surgical route on feline contraception.
There is a third option which is artificial stimulation of the vagina. It’s a non-chemical method but it requires skilful expert handling and only by a veterinarian or vet tech. Although I’d expect some breeders to do it from time to time.
It involves stimulating the female cat on heat with a glass rod, a blunt-ended plastic rod or a cotton-tipped swab. An assistant holds the cat by the scruff of the neck and her tail is raised to allow the insertion of this object into her to about 13 millimeters and rotated.
The female cat exhibits all the signs of mating including crying out and the postcoital rolling over behaviour. She should exhibit these signs if you want to be sure that the process has been effective.
Great care is required which is why it should be carried out in a veterinary clinic. There is the risk of injury with repeated attempts.
Because the mating acting cats induces ovulation, the female cat ovulates when stimulated like this as if she is carrying male sperm.
Because she is not, the eggs that she sheds will be wasted and in effect contraception will have been achieved.
Her sexual appetite passes and she will be quiet again until her next heat. She will have experienced a phantom pregnancy because of this treatment.
My veterinary reference book tells me that after this procedure is carried out successfully the female breeding cat will go out of heat in 3 to 4 days. She shouldn’t be allowed outdoors while still in heat because if she should meet a tomcat i.e. an unneutered male cat, pregnancy will almost certainly result.
Many queens will go back into heating after about 44 days “when the ovaries stop manufacturing progesterone”.