SENILITY IN DOGS AND CATS

Now that dogs and cats are living longer lives, we see more older pets with signs of mental deterioration.  In dogs there is a specific syndrome called "Cognitive Dysfunction", which is similar to Alzheimer's Disease in humans.  Older cats also commonly show senile symptoms.
The signs of senility in dogs include sleep problems (restlessness at night or sleeping abnormally deeply with difficulty rousing), disorientation, forgetting to be housetrained, or anxiety.  In cats, the most common sign of mental deterioration is aimless vocalization (often at night) and changes in housetraining.
Because the signs of many physical diseases make it hard to evaluate the behavior of the older pet, a thorough physical and blood and urine tests are necessary to rule out physical causes for geriatric behaviors. 
Once physical causes are ruled out, there are a number of treatment options for senile dogs and cats.  Initially, exercise and mental stimulation will help keep the mind more fit and slow mental deterioration.   For dogs, regular walks have a very positive effect (another reason for treating your dog's arthritis to allow more activity).  All types of games and toys that keep your pet's mind active will be beneficial.  Rituals and predictable activities make the pet with an aging mind more secure and happy; invent enjoyable activities that can be performed in the same way at the same time every day.
A number of nutritional substances have been shown to improve brain function, including Omega 3 Fatty Acids and a variety of antioxidants, including Vitamin E.  These nutrients have been combined at optimal levels in a diet called B/D (for "brain diet"), produced by Hills and available at Sacajawea Healthcare for Pets.  The research results on this diet have been surprisingly good, and we have a number of dogs that have shown definite improvement in their brain function after a month on the diet.
There are also a variety of drugs that have shown reasonable effectiveness on restoring brain function.  The only one approved for use in dogs is Anipryl, but a number of human Alzheimer's drugs also show promise.
Ginkoa Biloba is an herb that has been claimed to improve brain circulation and memory in humans.  Recent studies have been contradictory, so we don't really know if Ginkoa has any positive effects, but it does appear to be safe.  Another "natural" product that has been used (but scientific evidence is thin) is lethicin, which is an emulsifier found in many food products.  Lethicin is a good source of choline, which is the raw ingredient of the brain neurotransmitter acetylcholine.  Again, even thought the evidence is scanty, the nutrient is safe and inexpensive.
Finally, some senile pets (especially dogs) suffer from anxiety due to their mental deterioration.  These dogs often wander around anxiously at night, and are very distressed.  Mild antidepressant medications are occasionally used to improve the quality of life of these dogs.
Ask your veterinarian about ways to improve your pet's mental function and quality of life.  There is help for senility.