• Cognitive dysfunction is an age-related neurodegenerative disease that impairs memory and learning.
• Symptoms and histopathological findings of CDS resemble forms of dementia seen in Alzheimer patients (Dementia Alzheimers Type (DAT)).
• CDS can manifest itself in multiple unspecific clinical signs that increase in quantity and severity over time in affected dogs. Print off the owner factsheet on Cognitive dysfunction to give to your client.

Presenting signs

• Summary:changes in cell function and neurotransmission in the brain of the CDS patient lead to malfunctions of short term memory, loss of learned behavior, impairment of the processing of sensory information, reduction in cognitive capacity, and alterations of mood. Taken together these create typical patterns of signs that owners recognize.
• Progression:the progress of CDS is related to the general rate of aging in the canine. Quite significant changes can occur in the space of weeks or months. Worsening of the condition may be precipitated by stressful events such as hospitalization, kenneling, surgery or a house move. Ideally, dogs should be behaviorally assessed before these events.
• Emotional changes:mild emotional changes may be the first signs of the onset of dementia. Signs include depression (reduction in activity, play and interest in activities the dog formerly enjoyed). A depressed mood is also a common sign of chronic pain and ill health. Increases in anxiety and fear leading to irritability and aggressiveness.
• Defects of short-term memory:the dog repeatedly performs certain actions such as asking for attention, food and other rewards. These behaviors may also be learned as a result of owner reinforcement. Malfunction of short-term memory is at the root of many of the problems seen in CDS.
• Disorientation:the dog has trouble recognizing people, locations, or objects. This may lead to secondary problems, such as house soiling and trouble to find locations in the home, eg door to outside, water and food dish.
• Changes in sleep-wake cycle:the dog tends to sleep mostly during the day and appears restless at night. Pain and illness are also significant factors in nighttime restlessness in dogs, eg chronic arthritic pain may make rest uncomfortable.
• Loss of learned behaviors:failure to respond to commands and social signals that inhibit unwanted behavior. This contributes to loss of social inhibition and alterations in relationships with people and other animals in the home.
• Loss of house training Lack / loss of or inadequate housetraining (example of a learned behavior):a previously house trained dog will suddenly urinate and/or defecate inside the house. This symptom can be caused by numerous medical and behavioral problems that have to be ruled out. Once the underlying cause of CDS has been treated the dog may need to be housetrained from scratch.
• Changes in interaction with the environment:reduced greeting of the owner, familiar persons or pets, decreased response to commands. A depressed mood and lack of interaction tends to isolate dogs from their owners, who may not instigate play or give attention. Through a loss of stimulation and reward of normal activity the degradation of the human-animal bond leads to social isolation that contributes to worsening signs of CDS.
• Neurological:in the latter stages of CDS, neurological impairment may be seen. These include ataxia Ataxia , apparent sensory loss (loss of vision/hearing) and changes in locomotor reflexes. Dogs can progress to this stage quite rapidly (within a few weeks). Any neurological signs must be investigated thoroughly as there are numerous other potential medical causes.

Age predisposition

• The onset of clinical signs is seen in older dogs, depending on individual differences, breed and size.
• CDS might occur as early as 7-9 years of age in large size dogs.
• Smaller breeds are typically affected later in life (10-12 years of age).
• In one study, 25% of dogs of 11-12 years were affected, compared to 68% of dogs of 15 years or older.

Breed/Species predisposition

• All breeds are equally affected, but some, eg the Beagle, may be predisposed.
• Smaller dogs are typically presented at an older age than large or giant breeds of dogs.