The heat or estrous cycle is the period of sexual receptivity in female dogs. The age and duration by which the dog begins her heat depends upon her size and the breed. Normally, the heat cycle occurs between 6-12 months of age. In smaller breeds, it can be as early as 5 months whereas in larger breeds, the cycle may not begin until the dog is 14 months old, or sometimes even later. The cycle usually occurs twice a year, and the duration is of approximately 3 weeks. During this period, the female dog is receptive to mating with male dogs and has a high chance of getting pregnant. To have a better understanding of the signs of a dog in heat, given below are the various stages of the average 3 week cycle.
Canine Heat Cycle Stages
Like humans, the canine estrous cycle has different stages that vary in duration and during which the dog undergoes different behavioral and physical changes. This cycle has four stages - proestrus, estrus, diestrus, and anestrus.
Proestrus - Symptoms
It is the first stage of the heat cycle which lasts between 7-10 days. The following are the symptoms of this stage.
- The changes in the dog may vary from quite mild to more severe. Some dogs may become more affectionate and clingy to their owners while others may seem a bit grumpy or fussy.
- It's quite unusual for your dog to undergo appetite changes, as very rarely do they go off their food or become hungry to the point of raiding the trash bin for discarded leftovers. Whatever be the change, keep it in mind as it can be a significant sign that the heat period has begun.
- Another sign is the swelling of the vulva, which can be noticed trailing up to the pelvic opening just below the anus. Along with the swelling, there will be bloody discharges from the vulva which is less during the initial few days but becomes a bit heavier till the midweek.
- The dog will try to guard the vulva, either by tucking her tail between her legs or sitting down whenever a male dog approaches the area.
Estrus - Symptoms
The onset of estrus characterizes the fertile portion in the female dog's heat cycle, where the ovaries start to release eggs for fertilization. This period lasts from 5-7 days, and the symptoms include the following.
- Pinkish-tan lightened discharge from the vulva is the first sign of the onset of estrus.
- The initial swelling of the vulva subsides and it becomes soft enough for penetration.
- Since the female dog is ready for fertilization, she will start flagging her tail to invite male dogs.
Diestrus - Symptoms
As diestrus starts, the fertile portion of the canine estrus cycle comes to an end and the female dog is less receptive towards male dogs.
- During this time, most of the swelling disappears, but the vulva still remains slightly enlarged.
- Whether bred or not, the female dog now lacks the conditions to mate and is no longer interested in mating.
- The pinkish-tan vaginal discharge turns red again but gradually tapers off over the course of the final week.
Anestrus - Symptoms
This is the resting period that lasts for 5-6 months in which the female dog undergoes no hormonal changes and prepares herself for the next heat cycle.
During the heat cycle, moderate exercises, short walks, or small periods of gentle play can keep the dog active, as neither excessive rest nor strenuous exercise is recommended for her health. A knowledge of the above will help you understand the behavior of dogs in heat, and the necessary measures and care you need to take of your pet during these days.