It's possible to spay a cat during the heat cycle, although many vets prefer not to do so. During the estrus cycle, the feline's reproductive organs and related blood vessels become engorged with blood. It takes more time to complete the surgery, so your vet or the facility might charge more
Spaying your cat is an important part of basic cat health care. Cat spaying at a young age prevents mammary cancer and spaying at any age prevents unwanted kittens, noisy heat cycles, and possibly even urine marking in the house.
Though spaying a cat in heat is not ideal, it can be done. However, there are some disadvantages to this. When a cat is in heat, the blood vessels that supply the reproductive organs and surrounding tissues become engorged with blood. The tissues may be more prone to tearing
You can spay a cat while she is in heat, and most but not all vets will do this. It will likely cost a bit more because there is more blood and it takes longer, but it is not significantly riskier, and is less risky than waiting around with a cat in heat. Cats can be in heat almost constantly until they get pregnant, so even if you did try to wait, you'd probably have the same problem later
The cat will stay in heat for a couple of weeks until the hormones in her bloodstream dissipate. She would not get pregnant if bred, but the act of breeding could rupture her internal stitches and result in severe internal bleeding and infection. She should be kept away from males for at least 3 to 4 weeks, then she is fine to be with them again