For many good reasons, horses are NOT good lawnmowers.

“When compared to ruminants, horses ingest relatively small amounts of food at each bite and eat at a rate 3-4 times slower than sheep and cattle” (RIRDC, 1999, Feeding Horses in Australia).

There are three big, life-threatening problems with keeping horses as “lawnmowers”.

1. Many grasses contain “oxalates”, which effectively leach calcium from the horse’s body and contribute to issues such as “big head”, in which the bones swell and soften.
2. Many grasses contain too much sugar in them, and the horses develop laminitis and founder, a potentially life-threatening condition in their feet that results in the hoof walls breaking away from the inner pedal bone inside the hoof, rendering your horse potentially permanently lame. It is an extremely painful condition and one that can come on suddenly and result in very high vet bills and corrective trimming and/or shoeing, if it is caught in time.
3. There are many plants that are poisonous to horses. It’s a myth that horses know what to eat. A hungry horse will eat anything that it can find. Paddocks that have mixed species of grasses and other plants (weeds) will mean that your horse can get toxic plant matter mixed up in the one mouthful. Some weeds, such as crofton weed, are actually appealing to your horse and he may eat it by choice over grass. Sadly, crofton weed (along with many other weeds) are potentially fatal to horses.

As far as your paddock is concerned, horses are selective grazers and will not eat many grass species and plants that an animal such as a sheep or cow will eat. If you want animals to keep your grass down, a ruminant may be a better alternative.

A horse is not a ruminant (like sheep, cows, lamas and goats).

To be clear, we firmly believe that all life is valuable, and a horse does not need to “do” anything in order to secure its place in the world. That is, just because it is not “working” does not mean it cannot exist. It is perfectly fine to have horses that are retired or at leisure in your paddock. But please be aware that horses kept on grass need to be managed actively to ensure they are getting the right nutrition.

Equine nutrition is a complex field so we strongly advise you to search the Internet, take a course, or buy some books on feeding horses and to constantly update your knowledge, even if you’ve had horses for 20 years.