If you own an old mare you may be considering putting her in foal.
Many mares continue to successfully produce foals into their late teens and early twenties.
However as a horse ages getting her into foal can become more difficult - mainly due to changes in the ovaries that occur as a mare gets older.
When attempting to breed a foal from an older horse or pony there are many things to think about and more to be aware of.
Mares will often successfully produce foals at an old age and suffer no ill effects from the pregnancy.
This is more often true in general of horses that have bred foals regularly; it is often more difficult to get an old mare in foal if she has not foaled before.
If you are thinking about putting an old mare in foal, you must consider the chances of the foal being carried to term.
There is a gradual decline in a horse's chance of conceiving with increasing age, and also more chance of losing the foal if the mare actually becomes pregnant.
Overall there is roughly a 50-55% chance of an old mare over 20 years old conceiving and carrying a foal to term, whereas a four-year-old mare would have more like a 75% chance.
In addition you are likely to have more success if the mare has had a foal before.
Before sending a horse to stud to be put in foal a general health check of your mare by a vet is advisable to examine her heart and lungs, for example, to see whether they can withstand the extra load of supporting the life of a foal as well as maintaining her own wellbeing.
An external and internal physical examination is recommended as, with advancing years, ageing changes can occur within the reproductive structures that may make a horse less likely to conceive and to maintain a pregnancy to full term.
A swab is usually taken by a vet for a fertility check- the best time is while the mare is in season.
This will tell you whether there are any undesirable bacteria present and also a microscopic examination of the smear would give information on the healthiness of her womb.
Generally you would want to avoid breeding from a mare with inherited problems . But conditions such as arthritis, unless very severe, in an older mare are unlikely to have any bearing on a horse's well-being during pregnancy.