Canine cognitive dysfunction (CCD) is a common canine geriatric disease and also a behavioral problem in aged dogs. A definitive diagnosis of CCD is established only by β-amyloidosis in various brain tissues observed after necropsy, whereas the clinical diagnosis is usually based on subjective and clinical signs-related questionnaires.
The purpose of this study was to set up various visual-discrimination learning and memory (VDLM) tests for CCD clinical diagnosis.
Thirty healthy owned-dogs, in which 15 were younger than 7 years old (young dog group), and the other 15 were 7 years old and up (aged dog group) were participated in this study. In order to further clarify the influence of aging on dogs' learning abilities, elder dogs which were older than 10 years old were especially designed as "elder dog group" in this study. The VDLM tests, including reward approach learning (RAL), object approach learning (OAL), delayed non-matching to position (DNMP) and size-discrimination (SD), were carried out in a modified Wisconsin General Testing Apparatus. Both correct approach time (t) and error frequencies (e) were recorded.
There were significant differences between young dog group and aged dog group, not only in RALt (P=0.036) and SDt (P=0.012), but also in OALe (P=0.002). There were also significant differences between young dog group and elder dog group in DNMPt (P=0.043) and OALe (P=0.018).
RAL, OAL, DNMP and SD tests could be good diagnostic methods for suspected CCD patients in clinical application.