Most of us are familiar with the connection between indiscriminate overbreeding and the increase in abandoned horses, fly-grazing and welfare cases.

We may be quick to apportion blame, yet the problem of saturating the market with poor-quality stock begins closer to home than many of us would like to admit.

Positive discrimination

Putting a mare in-foal because she is too old to be ridden, has a behavioural problem under saddle, has gone lame or has been outgrown is never a good reason to breed.

Before they breed from their mare, both professional and amateur owners should make a realistic assessment of their chances of finding a market and a good home for the foal.

There will always be a demand for high performance horses among professional riders, yet that market is limited. Many amateur riders have moved, for financial reasons, towards breeds and types which can undertake multiple roles and be ridden by several members of the family.

Honest assessment of whether a mare has good enough conformation and temperament to breed from, and careful choice of stallion to match the foal to the market, will be key to responsible breeding over the next few years.

Don’t pass on the problem

Media coverage in recent years has highlighted the need for dog breeders to select against hereditary traits which cause welfare problems.

The same is true of horse breeders. A review by Bettley and co-authors in 2012 suggested that 21.2% of horse breeds worldwide are predisposed to one or more inherited disorders.

Some of these inherited disorders are caused simply by a genetic abnormality.

For those where the genetic mutation has been identified and individuals can carry the gene without exhibiting symptoms themselves, pre-breeding genetic testing to identify carrier mares and stallions can be used to avoid welfare problems in offspring which could be created by crossing two carriers.

Examples of this are testing for the genetic abnormalities which cause the neurological condition cerebellar abiotrophy in Arabians, and fragile foal syndrome (extreme skin fragility) in warmbloods.

Other types of welfare problems which seem to have an inherited component are harder to avoid. Osteochondrosis (OC), for example, a developmental orthopaedic disease of growing horses, which can cause lameness and affect athletic performance, is known to occur in some breeds more than others. It appears, however, that OC is caused not simply by genetic effects — it is also influenced by nutrition of the pregnant mare and of the foal, skeletal growth rates, endocrinological factors, exercise and biomechanics.

There is no simple genetic test for predisposition to the condition, but some studbooks have implemented a policy of not allowing stallions who show signs of OC on X-rays to be licensed for breeding.

A humane approach

Although there are some very good surveys of British equine welfare in general, there is little information about welfare problems relating specifically to breeding animals. Anecdotally, lack of regular foot care, dental care and parasite control for broodmares can be a concern.

There is also increasing awareness of the welfare issues which can arise as a result of the way in which stallions are sometimes kept, either in isolation or in stallion barns. Such systems are a long way removed from the way in which a stallion would interact with his “harem” of mares in the wild, and can cause stress which results in behavioural abnormalities.

Recent work by Burger and colleagues in Switzerland suggests that housing stallions alongside mares may both reduce stress and increase fertility.

Equine embryo before and after biopsying

Equine embryo before and after biopsying

Morals and modern techniques

Anyone who has been following the recent debate in the UK about “three-parent babies” (mitochondrial transfer) will be aware that the use of assisted reproductive techniques (ARTs) often throws up ethical dilemmas.

At the recent Equine Symposium of the International Embryo Transfer Society (IETS) in France, a whole session was devoted to the ethics and social acceptability of these techniques.

ARTs can be used to enhance equine welfare. The use of shipped semen, for example, whether chilled or frozen, can abolish the need to expose horses to the stress, disease and injury associated with transporting stallions internationally, or with sending mares and foals away to stud to live in unfamiliar groups.

The development by Choi and co-workers of a technique for biopsying equine embryos to diagnose genetic diseases such as hereditary equine regional dermal asthenia (a genetic defect in the collagen that holds the skin in place) also has positive welfare connotations. Using this technique, painful hereditary diseases which often require humane euthanasia at an early age can be avoided, since only those embryos without the genetic abnormality are transferred to develop into foals.

3 AI pic1

There are good welfare and ethical arguments, then, for embracing ARTs in equine breeding. However, it is also true that we are lacking information about the possible welfare costs of using such techniques.

The most obvious example of this lack of information relates to equine cloning, which, particularly since the FEI changed its rules in 2012 to allow clones and the offspring of clones to compete, is now a reality.

Concerns still exist about the abnormalities and illnesses which are known to occur in clones of other species at all stages of their lives, and about which we know relatively little in horses.

Such problems are likely to be technique-related and may diminish as techniques improve. Work by Katrin Hinrichs’ group in the USA has shown that cloned foals suffer a higher rate of abnormalities than non-cloned foals, and require intensive care if they are to survive the neonatal period. Partly because there are, to date, few equine clones to study, the long-term health of cloned foals is as yet unclear.

Discussion among international equine reproduction experts at the IETS meeting demonstrated that it is not just cloning about which we are lacking information — in fact, we know very little about the welfare effects of all equine ARTs.

There have been no controlled studies assessing whether techniques as simple as artificial insemination or embryo transfer, or as technically demanding as oocyte (egg) retrieval, cause pain or stress to the mares involved. Nor do we have much evidence about the long-term health of foals produced by methods such as intracytoplasmic sperm injection, an in-vitro technique where one sperm cell is injected, under microscope guidance, into the oocyte as a method of creating an embryo.

Research which provides this information, combined with careful selection of breeding animals and thought about their management, is necessary to make equine breeding as ethical and as welfare-friendly as possible.

Ref: Horse & Hound; 9 April 2015