The peak time of urban horse use was the end of the 19th century. Trains were bringing people and goods into cities, but horses were still used for transport within cities. They were used for short-haul trucking, delivery, and for street cars.
The average working life of an urban draft horse was apparently about 6 or 7 years. I assume they were slaughtered after that when they broke down.
Urban work horses were almost all geldings. The mares were too valuable as broodmares for producing more horses for this endless market.
My guess is that underfeeding was more of a problem for these horses than overfeeding. They would have no access to pasture. The SPCA in Britain was I believe first created to address the problem of cartage horses in London. They handed out the novel “Black Beauty” for public education.
I would assume that any Cushing’s symptoms in horses that lived into their late teens would just be considered signs of old age, Certainly even in the 1970s, when I was a kid, Cushing’s was not generally known about, and when I saw old horses with shaggy hair, warped feet, and prominent back bones I just though that was what happened to old horses. BTW, we though a horse over ten was old!
