From Wiktionary, the free dictionary
From kennel + mate.
kennelmate (plural kennelmates)
- A dog from the same kennel, or the same breeder.
2010, Carol Bradley, Saving Gracie: How One Dog Escaped the Shadowy World of American Puppy Mills:For the next four and a half months, Dog 132 would be called Wilma. Her kennelmate was Patty.