Why is CCDS considered a 'diagnosis of exclusion'?

• A. Because it can be diagnosed with a simple blood test
• B. Other neurologic, endocrine, or metabolic diseases must be ruled out first
• C. Because it does not require clinical signs
• D. Because it is contagious

Answer: (B)

A diagnosis of exclusion means CCDS is confirmed only after you have ruled out other conditions that could cause similar cognitive and behavioral changes. In senior dogs, signs such as disorientation, altered interactions, sleep-wake cycle disturbances, or house-soiling can arise from many problems, not just CCDS. Because there isn’t a single test that definitively confirms CCDS, a thorough workup is done to exclude neurologic, endocrine, or metabolic diseases that could mimic it. This typically includes a complete exam, basic blood work and metabolic panel, thyroid testing, and any imaging or additional tests guided by the dog’s signs. Only after these conditions are reasonably ruled out do you attribute the symptoms to CCDS. It isn’t diagnosed by a simple blood test, it does require clinical signs, and it isn’t contagious.