Overview of possibly diagnostic canine cognitive dysfunction indicators in magnetic resonance imaging

Abstract

Lately dementia patients of veterinary medicine have been carefully monitored. Dog-models of human Alzheimer’s disease (AD) is the reason for growing Canine Cognitive Dysfunction (CCD) syndrome awareness. CCD is a condition, that causes neurological symptoms in predominantly elderly dogs. The most usual symptoms are disorientation, impairment of house training and social interactions, mixed-up sleep-wake cycle. This disease also causes anxiety, deterioration of object recognition and memory. Luckily, certain diagnostic imaging techniques allow to achieve an early, non-invasive diagnosis. Magnetic resonance imaging of the dog’s brain in all 3 dimensions provide us the measurements that have been described to be indicative of CCD. Dorsal planes let us measure the width of the ventricles and total brain width. Transversal T1 and T2 sequences are used to calculate the size of the inter thalamic adhesion. Mid-sagittal tomograms are used to measure the area of the inter thalamic adhesion. Later, ratios and additional calculations can be acquired. During the past year, the neurology team of the Dr. L. Kriauceliunas Small Animal Clinic evaluated a handful of CCD cases. Using 0,4 Tesla APERTO Lucent Open system MRI machine (Fujifilm, Minato City, Tokyo, Japan), we examined the brains of fifteen (n= 15) elderly dogs, that met the requirements. All of the patients were overall healthy, had no additional inflammatory, neoplastic or ischemic diseases and were older than 10 years of age. The mean ± SD of brain width in our study was 50.16 ± 4.44 mm, the ventricle width was 26.08 ± 2.71 mm, inter thalamic adhesion size was 5.03 ± 1.10 mm and the inter thalamic adhesion area was 30.91 ± 7.95 mm2 (p<0.05%). After analysing the clinical examinations and manifestation of the disease, 11 dogs (n= 11) were described as severely ill. They all had similar reasons for the visit: unexplained anxiety, restlessness, vocalizations at night, decreased urinary continence, affected hearing, aimless walking and wandering. Statistic data of dogs with more expressed CCD symptoms resembles current scientific knowledge. Their mean ± SD of brain morphometric parameters were smaller: brain ventricle ratio was 0.53 ± 0.06 mm, inter thalamic adhesion size was 4.66 ± 0.95 mm and the inter thalamic adhesion area was 28.52 ± 7.41 mm2 (p< 0.05%). It is already known that canine cognitive dysfunction disease has multiple aetiology factors that are hard to distinguish in practical work. This study is a further proof that elderly dogs are predisposed to dementia and senile brain changes. Nevertheless, CCD presentation in MRI is usually directly related to the severity of clinical representation and not the animal’s age. This means, that there are multiple factors for the onset and progression of the disease, which we are yet to discover.