Service Animal:an animal that has been specially trained to help someone, for example a guide dog (a dog trained to help a blind person move around safely)
Noun/ my dog is registered in service animal
sheepdog: an animal that has been specially trained to help someone, for example a guide dog (a dog trained to help a blind person move around safely):
Noun/ I have a sheepdog on my farm.
Herd: a large group of animals of the same type that live and feed together
Noun/ there is a flock of sheep outside my house.