Heat (oestrus), Mating and Pregnancy

Heat (oestrus) is the period when the female show a desire for the male. After a successful mating the animal becomes pregnant Pregnancy lasts for 11 months in the horse and 12 months in the donkey. Donkeys and horses can be mated to produce hinnies or mules.

Recognising heat in the Equine

The Donkey and Horse comes into heat in spring or early summer. The female horse (mare) comes into heat for the first time at about 18 months of age. However the mare should not be allowed to mate (mounted) until she is 3 years old when she will give birth at 4 years of age. The female donkey (jenny) comes into heat for the first time when she is 1 year old. The mare is in heat for 7 days while the donkey is in heat for 2 to 7 days. During this time the female will accept the male. It is best to mate the animals in the last 2 days of the period of heat. The signs of heat are very clear. The female frequently urinates and mucous is discharged from the vagina, she shows a strong desire to mate. If mating is not successful and pregnancy does not result the mare will come into heat again 14 to 16 days later while the jenny donkey comes into heat after 2 to 3 weeks.


Choosing a good male for mating is very important. To produce a good foal you need good genetic characteristics from both parents. If you have valuable horses it is a good idea to apply a twitch to the mare and hobble her before bringing the stallion to her as she may otherwise kick and injure the stallion.


Pregnancy lasts for 11 months in the mare. She will show an enlarged abdomen during the last 3 months of the pregnancy. The udder will develop in the last month of pregnancy. The donkey is pregnant for 12 months. Pregnant animals should not be ridden or worked in the last 3 months of pregnancy.

Caring for pregnant animals

The pregnant animal should be fed well especially during the last 3 months as the foal may die if the mother is not well fed.

Hinnies and Mules

The father of the hinny is a horse and the mother is a donkey. The size of the hinny will depend on the size of its mother, the bigger the mother the bigger the young. The mother of a mule is a horse. Mules are powerful animals while hinnies have endurance (stamina).