Here's some information from Lap of Love Veterinary Hospice
What is it? In dogs with Cognitive Dysfunction Syndrome (CDS), the brain undergoes a series of changes that result in a decline in the mental faculties associated with thinking, recognition, memory, and learned behavior. Fifty percent of dogs over age 10 will exhibit one or more symptoms of CDS. Cognitive dysfunction is a progressive disease with increasing signs of senile behavior, similar to the behavior demonstrated by humans with Alzheimer’s disease, even though physiologically it is more similar to Parkinson’s Disease.
How is it treated? The only effective treatment at this time is an oral medication known as deprenyl (Anipryl) that treats the associated signs and increases brain concentrations of dopamine. Some dogs show a marked improvement while others do not respond at all. It may take up to 2 to 3 weeks to see improvement of clinical signs. Some herbal remedies have shown to be beneficial.
What is the prognosis for cognitive dysfunction syndrome? Prognosis of this disease is dependent on the response to treatment. Prognosis is poor for those dogs that do not respond to medical therapy, as their condition will continue to deteriorate. Progressive disease will eventually lead to a static lifestyle for your pet or may cause him/her to be put in harmful situations. Often there is not a crisis situation, but rather a steady decline in quality of life. It can be a difficult decision to end the life of a pet whose body may be functioning well, but whose mind is not. A personalized treatment plan is important to manage CDS. Talk to your veterinarian regarding the best treatment protocol for your pet.