A 2-year-old Chihuahua had a 4-month progressive history behavioral change and yelping episodes. The dog presented for investigation due to a recent onset of 'air-licking' and bruxism.

An MRI of the brain was performed - see pictures below.

There is a generalized mild widening of the cerebral sulci and moderate widening of the cerebellar fissures. In addition, there is generalised thinning of the cerebral cortex and mild reduction in the size of the interthalamic adhesion. The ventricular system is markedly dilated, especially the lateral and fourth ventricles. The lateral ventricle/brain index is 0.78 consistent with moderate hydrocephalus. The lateral recesses of the fourth ventricles are markedly dilated. Both the third and fourth ventricles mildly expand into the supracollicular space, causing mild mass effect on the rostral cerebellum.

One of the differentials for such generalised brain atrophy in a young dog is neuronal ceroid lipofuscinosis (NCL). Upon testing the dog was found to be homozygous for the causative mutation for NCL in the MFSD8-gene, previously documented in this breed (https://www.sciencedirect.com/science/article/pii/S109671921630083X?via%3Dihub)

Bruxism is a repetitive masticatory muscle activity characterized by clenching or grinding of the teeth, or by bracing or thrusting of the mandible, or both. For more information, click on the link below.

Courtesy of Dr. Koen Santifort.