As the weather starts to become a bit warmer and the days begin to lengthen, entire female cats start to come on call - this is also known as coming on heat or into season. Their behaviour can appear quite alarming to anyone that has not seen a cat on heat before and can be mistaken for an injury or illness such as urinary tract infections, a broken back or behavioural problem. If you are unsure if your cat is in season, your veterinary health care team will be happy to provide advice.
What does being on heat mean?
This is just another term for a cat being in oestrus or being receptive to being mated and becoming pregnant.
When do cats come on heat?
Oestrus begins when female cats reach puberty, which can be as early as 4 months right through to 10 months of age.
Exactly when a cat starts coming on heat is determined by a number of factors including: the days becoming longer (ie Spring/ Summer), the cat’s weight, age, general health and their breed. Although, it should be noted that cats can come on heat and produce kittens at any time of the year if the situation is right
How often do cats come on heat?
Cats are known as a polyoestrus species. This means they can come on heat multiple times in a calendar year (compared to dogs that are dioestrous and only come on heat twice per year).
Female cats will generally continue to come on heat until they are mated and become pregnant. Oestrus lasts for 7 to 10 days and there are 3 possible outcomes:
- The cat mates and becomes pregnant. She will generally come back into season approximately 8 weeks after the birth of the kittens (with a range of 1-21 weeks) . This usually coincides with the time the kittens are weaned.
- The cat mates, but does not become pregnant and has what is called a pseudo or “false” pregnancy. In this situation she can show all the signs of being pregnant (gain weight, increase in appetite and even produce milk) but won't actually have any kittens. She will return to being on heat approximately 4-6 weeks later.
- The cat does not mate. She will come back in to season 1 day to 2 weeks later and this cycle can continue multiple times unless she is mated or the breeding season ends.
How do I know if my cat is on heat?
The signs of oestrus are mainly behavioural and can include:
- Increase in vocalisation - This is often described as a yowl and is louder than your cat’s normal meow. It can sometimes be confused with an expression of pain or anxiety.
- Increase in affection towards people and cats alike. Rubbing against or weaving between legs and rolling around on the floor. Although contrary to this some female cats can become aggressive towards their owners and other cats.
- Change in mannerisms - When you stroke your cat along her back she will lower her front half, raise her bottom in the air, start to tread up and down and move her tail from side to side.
- Increased attention to the genital region (licking).
- Reduced appetite.
- Spray urine on walls and other surfaces.
- Increased insistence to go outside.
Some cats are known as 'silent callers' and may display none of the above signs.
Breeding your cat
A litter of kittens can be a wonderful experience if you are well informed and prepared. Children especially can learn a great deal from the experience of caring for the mother cat and the kittens.
Some things to consider are:
- Your cat’s temperament (as she will pass this on to her offspring).
- Whether you will be able to find good homes for all of the kittens.
- Is your cat free from hereditary diseases? These will also most likely be present in her kittens.
- Cats do not need to have a litter of kittens, people in general breed cats for their own sake, not their cats.
- Is your cat healthy? For example, free of feline AIDS (FIV), cat flu and feline leukaemia.
- Are you prepared for all possible outcomes? For example, if your cat has trouble during the birthing process or becomes unwell during the pregnancy.
Please contact your veterinarian for information about breeding your cat, her nutritional requirements during her pregnancy and lactation. They will be able to discuss what the possible risks with her particular pregnancy may be and how best to avoid them.
When kittens reach around 8 to 12 weeks old, it is time for them to find a new loving home, ideally someone who will adore them as much as you do. Here are some tips for achieving this.
Ensure the kittens are completely weaned. This normally occurs around 3 to 4 weeks of age, but can continue much longer. This process can be assisted by limiting the access to the milk source and encouraging the kittens to eat wet kitten food on their own.
- Handling the kittens will ensure they are used to being patted and held. It is also important that they spend time as a litter and with their mother to develop normal cat behaviour.
- Have the kittens vaccinated and vet checked at 6 to 8 weeks of age. They will need to be regularly treated for intestinal worms.
- Ask for a small fee to cover your feeding and vaccination costs. Many places recommend this as they feel it places a value on the kitten and that they are more likely to be well cared for.
- Discuss with potential owners that the cats need to be desexed at 5 - 6 months of age, require a series of vaccinations and treatment for fleas and intestinal worms. Ensure that it is understood that they can return the kitten if they need to. Encourage that they take their new kitten for a “new kitten check,” where the vet and the vet nurse will discuss the best way to care for their kitten.
- Ask your vet or vet nurse if they know of anyone looking for a kitten that would be a good owner. You can also ask if you can place up a notice in the waiting room with details of the kittens.
Importance of cats being spayed or desexed
Spaying is a surgical procedure that removes the ovaries and the uterus in female cats, meaning that they are no longer able to come on heat and become pregnant.
Apart from the prevention of unwanted kittens, spaying also has a number of medical benefits for your cat. These include preventing an inflammation of the uterus (metritis) or infection in the uterus (pyometra), mammary gland tumours and other neoplasm of the reproductive system and ovarian cysts.
Many people decide to get their female cat desexed as they are concerned about her getting out when she is on heat. Not only is there a risk of her getting pregnant, but there is also a very high risk of her getting hit by a car or getting injured as her only focus is on finding a male to mate with.
There are many things to consider when deciding whether to breed or desex your female cat (Queen). Please feel free to contact your veterinarian or veterinary nurse to discuss any queries that you may have.
 "Compendium of Animal Reproduction” Intervet International 1995