What kills old horses?

So, yesterday I talked about how horses don't get heart disease. What do old horses generally die of?

Obviously, in fiction, you don't have to be specific. "Old age" is as good as anything. And, depending on your culture, horses may not get to die of old age anyway - even growing up in England I saw old horses sent to the "hunt" - to be fed to the hounds. That practice isn't as common as it was, but...

But let's say your hero has put his beloved steed out to pasture behind his castle to live out his days? What's most likely to carry the old equine off.

1. Getting so arthritic he can't move or lies down and can't get up. Horses, like many large quadrupeds, will actually die from pressure on the internal organs if they stay down for extended periods of time. In modern times, sick horses are sometimes put in a sling to prevent that from happening. This would likely be a common fate of war horses, especially destriers, who worked hard in much the same way as modern sport horses. I've personally known about five animals this happened to. Once a horse gets to this point, the kindest thing to do is euthanasia. Sometimes you can get them up, but they often just go down again.

2. Colic. Colic, which I'll discuss separately, is the number one killer of horses of all ages. Old horses are less likely to recover.

3. Choke. I've already said that old horses lose their teeth. This makes it harder for them to chew their food. This means they're more likely to choke on it - which can easily be fatal in an animal with no gag reflex.

4. Nutrition failure. Best way I can put it. Between their teeth disappearing and their digestive system aging, old horses sometimes just become malnourished and starve to death. With modern care there's no excuse for this to happen - we now have special feed designed for ancient horses and there's ways you can make their life easier without teeth. But at lower tech levels, this would have happened all the time.

5. Liver or kidney failure. The liver is often the organ that goes first in old horses because their diet - and the supplements we give them - puts quite a bit of strain on it.

6. Cancer. Horses get cancers of various kinds just as much as any other species. Grey horses have a particular problem. The greying process is not a lack of pigmentation in the hair so much as all the pigmentation being concentrated in the skin. This results in a high incidence of "grey horse melanoma" - skin cancer. In most cases, grey horse melanoma just results in unsightly lumps, most commonly around the tail head, but it can spread into internal organs.

So, there you have it - a few problems your old nag might have. Note that the equine lifespan has increased dramatically in the last twenty years or so, with more and more horses surviving into their thirties.

In his twenties in this shot, Cowboy is now 35 years old and still teaching little kids to ride.

How Old Does A Horse Need To Be Before Being Ridden?

There's actually some argument about this. Depending on who you ask, you'll get answers varying from 18 months to 6 years old - and you'll hear good arguments on either side.

I grew up with an answer of "Three and a half - with full work not starting until 4." Most racehorses, however, are broken to ride at about 18 months - long before they stop growing. And in the United States, riding horses are usually broken somewhere between 18 months and 2 so they can be shown in under saddle futurities.

It's easier to train a younger horse, but training them too young can cause joint and back damage. Breaking horses in younger than three is a relatively recent thing that came out of the popularity of 2 year old races (the Kentucky Derby used to be considered a "futurity" for young prospects, not the peak of a horse's career). So, for wordbuilding purposes, it's probably best to assume that most people are breaking horses at 3-4. In modern horse training circles we talk about whether the joints have "closed" and many feel it is cruel to ride a horse before certain joints have closed, that is, stopped growing and developing. I still hold to the "four years for full work" rule.

Harness horses can be trained a little younger as pulling is easier on their bones and muscles than carrying. Leaving it much past 5 means your horse starts to mature a little too much mentally and then they take, like older people, longer to learn everything.

Mules and donkeys/burros take longer to mature, and the muleskinners I've talked to recommend 5 for breaking and 6 for full work.

How Long Do Horses Live?

Anecdotally, this looks to be the most common question non horse people ask. They want to know how long they live.

The simple, uncomplicated answer is that the expected lifespan of a horse is about 25 years. Ponies live longer.

However. In the UK we have a saying called "Donkeys' Years" - it means a long time. The average lifespan of a donkey is 45-50 years.

Mules live 30-35 years on average.

Also, the 25 year estimate is an average. I have known horses to live much longer, including one pony that made it to an estimated 48 (He had no papers) and was believed to be the oldest equine in the state of Maryland. I also know two horses that are both celebrating their 35th birthday this year. A well cared for animal with good conformation and genetic health can live longer, and advances in geriatric medicine are pushing the 25 year estimate closer to 30 - providing the horse isn't overworked at a young age, neglected, etc.

The horse year "ratio" is 4 to 1, but this method definitely breaks down. Here's a better pattern for a horse's lifespan:

Gestation: 11 months.
Weaning: 12 months in the wild, usually 6-8 months when domesticated.
Puberty: Somewhere between 18 months and 2 years. Unlike in humans, colts hit sexual maturity faster.
Full physical maturity: 4-6 years.
Old age: 18 years plus. (Some people put it at 15).

So, horses are fairly long-lived animals, with donkeys and mules living even longer.