the lad i used to go lamping with bred a litter of bull/whippet x's once, and kept back a pup for himself. picked the strongest looking one, but once it was grown it went off its food, didn't want to come out of the kennel, wouldn't work, but it doted on the lads girlfriend. he took it to the vets, and the vet said that it was depressed. he thought this was a load of b******s, and persevered, but to no avail. in the end he gave the dog to his girlfriend, now it is perfectly normal, eats well, and is game as anything! so dogs can get depressed!