After approximately age seven, the domestic dog requires closer observation and special treatment. There are now available many foods for senior dogs. These foods cut down the amount of protein and add certain, much needed supplements to the diet. These supplements assist the dog's ability to withstand certain conditions, such as arthritis.
Additionally, there are often behavioral changes in senior dogs. As a dog develops adult cataracts (approximately age nine in most breeds), certain behaviors may also be seen. These may include excessive barking, "staring", inability to find the back door without voice signals, inappropriate urination/defecation under windows, etc. Deafness can also result in behavioral changes, the most prominent being inappropriate vocalizing. Your senior dog requires a Veterinary examination every SIX MONTHS. It is no longer unusual to see aggressive cancers in older dogs. This condition will cause drastic loss of muscle mass and weight and will give no other warning in many cases. Your senior dog should have a full body x-ray and super chemistry to begin with, and then a six month followup to be certain s/he is still in good health. Do not overexercise a senior dog nor expect that dog to begin an exercise regimen with you, unless your Veterinarian gives the go ahead!
Your dog has been a good friend to you and, during his/her senior years, it is your job to be certain that quality of life is as good as it gets. S/he can't speak, can't tell you if something hurts. Senior dogs are marvelous companions but they DO require extra care. If your dog begins to demonstrate unusual behavior, do NOT hesitate! See your Veterinarian immediately.