Why horses lie down when it rains?

Horses don't actually lie down *because* it rains. There are a few reasons why a horse might lie down during a rain shower, but it's not a direct response to the rain itself. Here are some possibilities:

* They're tired or relaxed: Horses often lie down to rest. Rain can be a peaceful and calming environment, which might encourage them to relax and lie down.

* They're trying to avoid insects: Rain can deter annoying flies and other insects, making it a more comfortable time to lie down and relax.

* They're hot: Horses can get hot, especially in the summer. Rain can provide a refreshing cool-down, and lying down helps them dissipate heat.

* They're sick or injured: A sick or injured horse might be more likely to lie down, and rain could be a factor in their decision to rest.

It's important to note that horses don't always lie down in the rain. Some horses may be more sensitive to the weather than others, and some may simply prefer to stay standing.