The desire to improve the lives of horses was at the core of the RSPCA's original foundation, with all of the founders being passionately concerned for their welfare in spite of differing views on how this might be achieved.
As large, charismatic mammals who are highly visible, horses are responsible for a large number of complaints about the RSPCA's inaction in the face of conditions which are not quite bad enough to be illegal. Animals who are not in fact suffering any welfare issues may be the subject of complaints if members of the public do not appreciate that native ponies are adapted to life outside during the winter (and may indeed be more likely to have problems in very hot weather or when unnaturally rich grass pasture is available).
Horses are also the subject of high-profile debate about acceptable working conditions and sporting events with a high degree of risk.
At one end of the scale there are native moorland ponies and ponies grazed by travellers on pieces of rough ground. The RSPCA may be pressed to take action when they are at risk in adverse weather conditions and also if pony owners dispose of surplus animals to the horsemeat trade.
At the other extreme are high-value sport horses who may be at risk of fatal accidents (e.g. in jump racing) and may be kept in restrictive conditions which do not satisfy their behavioural needs. If they cease to be valuable because of age or injury they may also be disposed of to the meat trade or may enter a downward spiral of less and less competent owners.
They are extremely expensive to care for and raise the ethical dilemma of what to do with animals who have been rescued but may never be fit enough to be placed in a normal working home.
The RSPCA attempts to place unrideable horses as companions, thereby incurring some criticism that this is a sentimental waste of funds.
What an enquiry might comment
In many ways the RSPCA's difficulties in coping with the current equine welfare situation mirror its problems with dogs in that there is a high demand for it to take action in situations where it has limited ability to do so, either because there are no legal powers to act or because it is limited by resource constraints.
If the legal position on horses left on grazing land without the owner's permission and horses straying on the highways is changed to permit landowners to dispose of animals there will probably be pressure for the RSPCA to take them in to prevent them from being euthanised. It is difficult to see how the society will cope unless more people are prepared to give practical or financial support.