Yes, farm animals do get struck by lightening unfortunately as do other animals and things. In fact some farmers actually have insurance in case that happens so they don't lose the money the cow was worth which sometimes can be over $100,000 even!
Here are a couple of websites that you may find interesting. Be sure to let me know after reviewing if you've any questions? Otherwise just click "accept" and leave a positive feedback as I will for you also. God Bless,Don
Cows & more ~
Not a horse or a cow but even a Giraffe was killed by lightening at Disney! (see next link)