Obesity is a very big problem in our society, and this problem goes for dogs as well. All dogs are susceptible to gaining weight as they become less active in old age. But some breeds have been reported to be more likely to become obese than others as they watch the birthdays fly by. West Highland white terriers, beagles, cocker spaniels, collies. cairn terriers, and retrievers are breeds that are noted for obesity in old age.

Fear induced aggression or pain induced aggression is a something that may affect all older dogs at some stage.  This is simply because many dog owners don't realize their aging dog is very sensitive to feelings of pain, surprises, and aggressiveness - even from innocent play.