MRI of the canine (& feline) Adrenal glands...

The adrenal glands in both dogs and cats are very well demonstrated using MRI. In both species the adrenal glands lie just to the medial aspect of the cranial pole of each kidney. The right gland lies between the kidney and the caudal vena cava while the left lies between the kidney and abdominal aorta. On sagittal examinations of the Lumbar spine both are often seen at the level of the coeliac and mesenteric arteries (L1-2). The animal will sometimes be cushingoid but some tumours don’t result in Cushings disease (depending on the cell type involved). Tumourous glands will often be markedly enlarged but also look out for loss of differentiation between signal from cortex and medulla. In adrenal dependant Cushings disease, over secretion of the affected gland can lead to atrophy of the contra-lateral side so don’t be surprised if it’s difficult to see the ‘normal’ adrenal. Case 1 shows a dog with Cushing’s disease. Ultrasound examination of this dog was said to have shown a normal left adrenal with the right being absent or difficult to demonstrate. MRI clearly demonstrated a small but normal right adrenal while the left is slightly enlarged and shows a clear loss of signal differentiation between cortex and medulla.