The days before surgery can be a slightly nervous time, even when the surgery is as routine as it gets. Your cat might be blissfully unaware that she's about to be desexed, but you certainly know, and a few concerns are perfectly natural. Since she's about to be desexed, you might not be paying close attention to her heat cycles. After all, they'll soon be a thing of the past. So what should you do if your cat goes into heat just before she's scheduled to be desexed?

Different Stages of a Heat Cycle 

Your cat's heat cycle has different stages. The preliminary stage is called proestrus, and is largely an internal process, meaning you're unlikely to notice any effect. The primary stage is called oestrus, when behavioural changes can be seen, and your cat is receptive to males, inviting breeding. Cats are subject to induced ovulation, meaning they only ovulate when stimulated to do so (via mating). Without ovulation, your cat enters a stage called interestrus, when the physical manifestations of the heat cycle subside, leading to an interval before proestrus begins again. It's certainly possible for pet desexing to be performed during proestrus and interestrus, but oestrus is another matter.

Slightly More Complex

During oestrus, your cat's reproductive organs (and the blood vessels that feed them) become engorged with blood. It's possible for desexing to take place during oestrus, but a routine procedure can become more complex due to the engorgement of the site. The risk of complications can be increased when a cat is desexed during oestrus, even though the risk is low. The added delicacy of the procedure can also mean you will be charged more for the service.

Time to Reschedule

If your cat should appear to come into heat just before her scheduled desexing, contact your vet. Desexing is rarely a medical emergency, and so it's just a case of rescheduling. Oestrus can last for 14 to 21 days, although there can be some significant variances, depending on your cat's age, health and even the amount of daylight they receive. Your vet can also opt to perform the desexing procedure in the early or later stages of oestrus, when engorgement of the reproductive organs is less pronounced.

While You Wait

If desexing is delayed due to oestrus, it's wise to keep your cat inside during her heat cycle in order to prevent an unwanted litter of kittens. Your cat's behaviour might be problematic if she's confined to your home during oestrus, so be on the lookout for destructive habits such as urine spraying and scratches to doors and windows as she tries to escape.

Desexing a cat depends on an available window of opportunity. Oestrus can close this window, but it's not going to be long before it opens again.