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Cornell Richard P. Riney Canine Health Center

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Cognitive dysfunction syndrome


Cognitive dysfunction syndrome (CDS) is a common age-related disease in dogs that affects the brain, causing deterioration similar to Alzheimer's disease in humans.  

Dogs may start to develop CDS around nine years of age, or older. The condition may be underdiagnosed since the behavioral changes progress slowly, and owners may assume that some changes are a normal part of aging.  

Early intervention with environmental enrichment, diet and medical management can improve the quality of life for dogs affected by CDS.  


CDS is caused by gradual and degenerative age-related changes in the brain.  

Cells called neurons play a key role in the brain by transmitting essential information throughout the body, helping regulate mental and physical interactions. But when dogs start to age, the cells in their brain, including neurons, start to waste away.  

One of the degenerative changes that occurs is the build-up of a protein called beta-amyloid, which creates toxic conditions for neurons. As the neurons stop functioning properly or die off, the brain loses its capacity for processing information, and this breakdown of internal communication leads to the physical and behavioral changes that owners observe. 

Clinical signs 

CDS may start as one clinical sign and progress over time, or have several apparent signs. The most common may include:  

  • Disorientation — Getting lost in familiar places, stuck in corners, staring into space 

  • Interaction changes — Suddenly clingy or avoidant, not recognizing familiar people 

  • Sleep pattern changes — Wandering the house at night, sleeping more during the day  

  • House-soiling — Urinating or defecating indoors when they were previously house-trained 

  • Activity level changes — Decreased interest in playing or doing other activities, restlessness, pacing 

  • Anxiety — Increased anxiety, new phobias, irritability, aggression 

  • Learning changes — No longer responding to previously known commands or struggling to learn new ones 


CDS is diagnosed based on the demonstration of clinical signs.  

Your veterinarian will perform a thorough physical exam and recommend checking blood and urine tests to rule out other conditions with similar signs, such as pain, arthritis, seizure disorders, systemic illnesses, and vision or hearing loss. In some cases, MRIs can provide advanced imaging to rule out brain tumors or other conditions.  


There is no one treatment or cure for CDS, and research is ongoing in this area. Any concurrent health conditions, such as arthritis and obesity, must also be addressed.  

Treatment may include a combination of the following: 

  • Diet — Certain prescription diets (Hill’s B/D, Purina Proplan Neurocare, Royal Canin Veterinary Canine Mature Consult) are rich in antioxidants, fatty acids and other important nutrients that help support the brain. 

  • Enrichment — Interacting with your dog regularly through play, varied or interactive toys, regular exercise and more can help stimulate their brain. 

  • Medications — Selegiline is a medication approved for CDS treatment in North America. Your veterinarian may also prescribe medications to address specific issues, such as anxiety.  

  • Supplements — A myriad of supplements may help with CDS when combined with the tactics above, such as Senilife, Novofit (SAMe) or Aktivait. Consult with your veterinarian before starting any supplements.   


CDS is a slowly progressive disease that many elderly dogs experience.  

Early intervention with diet, enrichment and medications can help slow the progression of CDS and improve their quality of life.  

Dogs who are severely affected with CDS or who have other compounding medical problems often have a worse prognosis and may not respond well to therapies.