Yes. I knew a family who had three and found out after racing how many
were just put down. My sister used to be a veterinary nurse and they
had to put down a dozen one morning. I was brought up with dogs and i
vowed to give a greyhound a home when i could be around during the
day.

Suzi was one who then turned out not to be able to cope alone - Xmas
2007 with my brother's three Whippets made an impression. Wouldn't
walk anywhere when we got back and i had to take her for walks with a
friend's dog. So a companion was required and Zak was the result -
Lurcher [Whippet/Irish Terrier] from a dog's home. It can happen with
greyhounds - they are kept in their litters through their racing
careers and some can't get used to being alone. Zak is a very
different dog from Suzi - for poaching a sighthound with its speed and
agility is crossed with a working dog [Collie or terrier] resulting in
an intelligent and highly obedient working dog.