What clinical criteria support a diagnosis of canine cognitive dysfunction and which interventions have evidence?

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Canine cognitive dysfunction syndrome (CCDS) is diagnosed by identifying progressive DISHAA behavioral signs, excluding comorbidities through physical, orthopedic, neurologic examination, and laboratory work, and confirming either a normal neurologic exam or symmetrical diffuse forebrain dysfunction with sign persistence after comorbidity management. This constitutes a Level 1 diagnosis; Level 2 adds brain magnetic resonance imaging (MRI) showing cortical atrophy with cerebrospinal fluid (CSF) cell counts within normal limits.1 The DISHAA domains — disorientation, social interaction changes, sleep-wake cycle disruption, house soiling and loss of learned behaviors, activity changes, and anxiety — are the core clinical framework. In dogs, the most commonly reported signs are daytime sleeping with nighttime restlessness, decreased interaction, disorientation at home, and anxiety; visual impairment, smell disturbance, tremors, and falling are also associated with the diagnosis and can aid early recognition.5 Severity is staged as mild (subtle, low-frequency signs with preserved function), moderate (more apparent signs requiring management adjustments), or severe (debilitating, overt deficits impairing basic functions and requiring comprehensive support).1 Prevalence increases sharply with age: approximately 14–22.5% of dogs older than 8 years are affected, rising to 23% of dogs aged 11–12 years and 68% of dogs aged 15–16 years with at least one consistent sign. Despite this prevalence, in one cohort of dogs aged ≥8 years with a 14.2% prevalence of CCDS, only 1.9% had received a veterinary diagnosis.38 Validated questionnaires are the primary diagnostic instruments in clinical practice. The Canine Dementia Scale (CADES) and the Canine Cognitive Dysfunction Rating (CCDR) scale both assess DISHAA domains and stage severity; the CCDR carries a reported diagnostic accuracy of 98.9%.413 CADES scores correlate with markers of neuronal death, amyloid pathology, and behavioral t