Guy Grinwis is appointed at the Veterinary Pathology Diagnostic Centre (VPDC) in Utrecht since 1990 where he currently is an associate professor in veterinary pathology. As such, he plays a leading role in the diagnostic service of the VPDC and is involved in post-graduate training of residents in veterinary pathology and residents in clinical veterinary sciences (e.g. internal medicine, ophthalmology, and oncology) as well as teaching students of veterinary medicine.

He has special interest in liver pathology and ocular pathology, and participates in (inter)national research projects on regenerative medicine and stem cells in the fields of liver disease, pathologies of the intervertebral disc, and tumours of endocrine organs.