The diagnosis depends largely on the owners and the veterinarians to observe and diagnose the disease, which is in most cases overlooked and symptoms attributed to the aging of dogs. To facilitate the detection of CCD, veterinarians can use a screening questionnaire that includes a list of possible signs. Several questionnaires are available and based on the scores the stage of dog’s cognitive decline can be identified (Colle et al., 2000; Neilson et al., 2001; Osella et al., 2007; Azkona et al., 2009; Golini et al., 2009; Salvin et al., 2011; Landsberg et al., 2012; Rosado et al., 2012; Fast et al., 2013b; Madari et al., 2015). Madari et al. (2015) have proposed criteria for discrimination of three stages of the disease, these are mild cognitive impairment, moderate cognitive impairment, and severe cognitive impairment. The severity and progression of CCD disease is identified by Canine Dementia Scale (CADES), which contains 17 items distributed into four domains related to changes in dogs’ behavior (spatial orientation, social interactions, sleep–wake cycles, and house soiling) (Madari et al., 2015). The Canine Cognitive Dysfunction Rating Scale (CCDR) is another questionnaire (Salvin et al., 2011), which is comprised of 13 behavioral items distributed into four domains, namely orientation, memory, apathy, impaired olfaction, and locomotion (Salvin et al., 2011). The cognitive deficits in dogs with CCD with regards to affected brain regions are summarized in Table 1. Cognitive impairment parallels the symptomology of AD. Performance on tasks involving complex learning and working memory are impaired first, along with executive function, visuospatial ability and complex learning deficits, with disease progression impairments in discrimination learning and behavioral changes are common (Neilson et al., 2001; Tapp et al., 2003; Studzinski et al., 2006; Madari et al., 2015).