Hello Thomas-the-spot!
Sometimes older spayed bitches can have a hormonal inbalance that can cause them to have thin/balding patches on their backs. This tend to be in a bilateral pattern, (the same on both sides). If this is the case, I suggest that the owners take their girl to the vet for a check-up. If the patches are not bilateral, then it is probably a skin problem, eg allergy, eczema etc. I know that certain breeds are more likely to have the hormonal inbalance, for instance the dachshund and the boxer but I'm not sure abou the CKC!
Hope this helps,
Ali :)