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If you’re thinking of breeding from your mare, there are physical conditions you should take into account, either because they can be inherited or because they may affect whether a mare can carry a foal to term. Below are some examples…
Sweet itch: It has been well established that there are genetic aspects to susceptibility to this serious skin condition, known scientifically as Culicoides hypersensitivity or insect bite hypersensitivity.
A breed predisposition is well documented for Icelandic and Welsh ponies. In addition, the disease does seem more common than would be expected in shire and Friesian horses and Shetland ponies.
Again, many environmental factors can affect the seriousness of the condition in any particular horse or pony. Nevertheless, a recent article suggested that, because of the probable inherited predisposition with the disease, affected animals should be removed from breeding programmes.
Sarcoids: There are degrees of susceptibility of horses to sarcoids and this has a heritable component. It is known that some families of horses are very badly affected with sarcoids and this can be seen through many generations.
However, if the environmental conditions are not right, the horse will not be affected no matter how susceptible it is. This is one of the reasons why it is difficult to give definite advice about the advisability or otherwise of breeding from horses with sarcoids: even if there is, as thought likely, inherited susceptibility to sarcoids, other factors also need to be present.
In broodmares it may be important to consider the location of the sarcoids; if they are around the udder it may be better not to put the mare in-foal as there is evidence for transmission by contact.
Weak hindlegs: In some horses, as they get older, the fetlock and suspensory apparatus of the hindlimbs begins to lose their strength and the fetlocks get nearer and nearer the ground. An in-foal mare carries an enormous extra weight, so it is important to consider carefully the ability of the mare to carry this as she gets to the end of a long pregnancy.
For the full article on assessing your mare for breeding, see the sport horse special issue of Horse & Hound (10 March, 2011)
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