I currently have two Ex racehorses and have re-homed many out of training over the years.
The official figures are approx 3,000 horses come out of training each year, of which 2,000 or so are re-homed to private homes, polo yards and hunting. This of course does not take into account the number of horses that don't even make it into training !! I would hate to guess how high that number could be. A lot of horses find themselves going back through the sales rings, and the ones with serious injury are often sent straight to the hunt kennels or Potters (one of only two horse abattoirs in England)or PTS by a vet. I think the figure you have been quoted of three months 'waiting' possibly relates to the current economic problems where private horse owners are unable to afford the upkeep of their 'pets' and due to the Animal Rescue centre's being full to bursting, are having no choice but to have their horses PTS. It's very expensive to have a horse PTS by a vet and disposed of by cremation. I'm sure many people would choose this route, but just cannot afford it, hence the increase in turnover at the abattoirs ??. Horses/ponies are not keep waiting at the abattoir, you would have to call and book them in just like you do with lambs/pigs/cattle.
I was talking to our Huntsman last week about the number of horses they have had in this winter, they normally have a 'flush' of elderly horses when the bad weather kicks in, but this year he has had a steady stream of 5/6 horses a week and they are still coming.
Back to the racehorses, I have to agree there's far too much indiscriminate breeding in this country. At least Thoroughbred Studs, like Darley are taking responsibly and have set up a re-homing program for the horses they breed. There's a lot of things I don't agree with in the Racing industry though, like the backing of yearlings and racing of two year olds - far to young in my opinion.
Either way it's all very sad