WHEN you decide to keep a dog, one of your main considerations will be which sex to go for - dog or bitch. It is generally considered that bitches are less aggressive (particularly towards other dogs) and make better companions than male dogs.

But keeping a bitch does present extra problems and responsibilities when your pet comes into season. A bitch in season is generally known as being 'on heat' and it is important for bitch owners to know what happens during this time and what actions should be taken.

The proper term for the season is the oestrus cycle and all female animals experience this in one way or another. It is a period of sexual activity and fertility when mating and pregnancy can occur.

The oestrus cycle of a bitch generally consists of two halves - a preparatory stage known as pro-oestrus and oestrus itself when the bitch is ready for mating. During pro-oestrus the vulva becomes swollen and a blood stained discharge appears which originates from the womb. The bitch frequently licks herself to keep clean but spots of blood will often be seen nearby, especially in her bedding.

Special nappie-like hygiene pants are available if the mess presents too much of a problem. The bleeding from a bitch during pro-oestrus is often mistakenly thought to be similar to menstruation in humans and other primates, but it is actually quite different. Bleeding in a bitch occurs before ovulation whereas menstruation follows ovulation in non pregnant primates.

Most bitches will begin their first season between six to seven months of age, but this can vary. As early as four months or even as late as two years have been known. The frequency of the season can also vary between bitches, but typically it is every six to nine months. A few days before heat commences some bitches may become more excitable and be less inclined to eat, possibly showing signs of abdominal discomfort from the onset of heat the bitch produces pheromones which can be detected as scent by male dogs from considerable distances.

Many male dogs will show interest in the bitch and again this can cause problems for the owner. During pro-oestrus, which last for about seven to 10 days, the bitch will not permit mating by the male, but after pro-oestrus comes the stage of oestrus itself when mating and pregnancy occur. This stage also lasts for about seven to 10 days making the duration of the whole season up to about three weeks.

After finishing a season, it is very common for a bitch to show signs of false pregnancy. Milk production to varying degrees and displays of nursing behaviour take place. This is quite normal and needs no treatment provided the signs are not too severe, in which case consult the vet.

Possible unwanted pregnancy and messy bleeding, combined with the need to keep your pet confined twice a year and deal with the attentions of the neighbourhoods randy dog population, should make the bitch owner consider some method of heat control. Whilst there are over the counter tablets and sprays to help mask the scent produced by a bitch on heat, the only truly effective methods are spaying or the use of artificial hormone treatment. Each method has advantages and disadvantages and the matter should be thoroughly discussed with the vet to find which method best suits you and your pet.

Dave Ashcroft - Owner of The Pets Emporium, College Street and Sutton Corn Stores, Junction Lane.