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Common Questions About Heat Cycles in Dogs and Cats

Common Questions About Heat Cycles

               Dogs and cats experience an estrus or “heat” cycle similar to menstruation in women in order to prepare the uterus for pregnancy.  Cycles vary somewhat between dogs and cats. Here is a brief overview of what occurs during a heat cycle and answers to common questions regarding the heat or estrus cycle.

               Female dogs reach puberty and have their first estrus cycle around 6-10 months of age, though occasionally the first heat can occur as late as 12-18 months. Smaller dogs tend to experience their first cycle earlier than larger dogs.  Dogs have approximately two cycles per year. 

               During the phases of the heat cycle, dogs will experience swelling of the vulva and a bloody vaginal discharge typically lasting one to two weeks.  As the cycle progresses, there is a period of about 5-9 days where the female ovulates and can be bred and become pregnant.  Females will often be more interested in males and allow themselves to be mounted by a male dog. If the female does not become pregnant, her cycle will end and the swelling and discharge resolve.  If she does become pregnant, she will carry puppies for about 63 days before they are born.

               Cats have a slightly different cycle—the first cycle typically occurs at 6 months of age.  Female cats can cycle multiple time during the breeding season or throughout the year. A heat cycle typically lasts about seven days.  If the female is not bred or does not become pregnant, she will go out of heat for one to three weeks then her cycle can occur again.  An average heat cycle occurs about once every three weeks unless the female is bred or spayed.  Cats will exhibit some light vaginal discharge but will have significant behavior changes in which they display overly friendly behavior rubbing on things, rolling on the floor, vocalizing, and raising their back ends in response to touch.   They may also display increased urination or urine marking. If bred, cats are also pregnant for about 63 days.

               What if I want to breed my dog?  Cells from the vagina can be examined by your veterinarian and blood tests checking progesterone may be performed to try to determine the optimum time to breed dogs during their cycles.  Work with your veterinarian to determine the best strategy if you are breeding dogs or cats.

               How do I prevent my cat or dog from getting pregnant?  Keep intact females who in heat indoors and do not allow them to interact with any intact males.  Strict vigilance is needed to prevent accidental breeding.  Of course, having your pet spayed is ultimately the best way to prevent pregnancy.  

               When should I spay my cat or dog?  Ideally cats should be spayed between 4 to 6 months of age BEFORE their first heat cycle occurs.  Dogs are a bit trickier.  Small dogs should be spayed around 6 months of age, but current recommendations for large breed dogs are to wait until the dog is mature at approximately 8-12 months of age.  These dogs may experience one heat cycle before being spayed. Discuss the pros and cons of when to spay with your veterinarian to find the best time for you and your pet.

               Can my pet be spayed while she is in heat?  Yes, cats and dogs can be spayed even if they are in heat. However, if it is possible to schedule their surgery during a time when they are not in the midst of their estrus cycle, the surgery may be a bit easier and there tends to be less bleeding during surgery.

               What does a spay surgery entail?  Spay refers to the removal of both the ovaries and uterus or an ovariohysterectomy.  This will prevent future estrus cycles and your dog or cat will no longer go into heat and cannot get pregnant. Spay also prevents development of a serious uterine infection known as pyometra, prevents ovarian and uterine cancers and drastically reduces the development of breast tumors in dogs, especially if spayed before they go into heat.

               This blog brought to you by the Patton Veterinary Hospital serving Red Lion, York and the surrounding communities.