Changing the food that you give your dog is an option, as some brands offer complete food for different life stages of a dog. This will help ensure that your dog continues to get the vitamins and supplements it needs. An older dog may develop a more sensitive stomach, so ensure its food is easily digestible and low in protein.
As a dog ages, it requires less exercise: more frequent, but shorter, walks may prove more beneficial. As it begins to exercise less, you should monitor its weight: an overweight dog will have more difficulty keeping stiffening joints supple, and excess weight worsens the symptoms of arthritis. Additionally, it will want to sleep more, so make sure it has warm bedding which is in a draught-free part of the house.
Consider what you can do to make your home easier to negotiate. You could consider an ergonomic feeder, or raising the food bowls, so that the dog does not have to bend to the floor to eat and drink. Try to minimise the number of steps your dog has to climb by moving his bed and food to the same level, or installing ramps. A pet ramp will help your dog in and out of cars as well. You can use a harness round its hindquarters to help you take weight off back legs when walking. It is important to keep your dog moving a little bit each day.
The pain from arthritis and other joint injuries can measurably reduce your dogs quality of life. Discuss with your vet the possibilities of using an anti-inflammatory drug to help ease joint pain. Dont use aspirin, there are medications which have the same effect, but are licensed especially for dogs. Giving your dog cod liver oil will help keep joints flexible, as well as improving its coat.
Physiotherapy and massage really help. Spend a few minutes every day rubbing up and down your dogs legs, especially the hips, in firm, circular motions to warm them up and ease them. Give your dog a rub down before and after walks as well. Your dog might respond well to acupuncture and other complementary therapies; it is worth exploring these options with your vet.