Across

1 single head of a herd, commonly cattle or sheep
8 horsehair
9 shepherd, one who tends sheep
10 loyal
11 to run back and forth
13 an animal, one without the skills to reason or think
15 horse
16 to graze
17 guardian

Down

2 a tail, as on an animal
3 a team of four horses
4 flock, group
5 cavalry
6 a sacrifice, such as an animal who is sacrificed
7 protect
9 animals when they are young, especially in relation to chickens and birds
10 wild, cruel
11 dog
12 sheep
14 horseman, one who takes care of horses