Maria Grazia Pennisi qualified from the faculty of Veterinary Medicine, University of Messina (Italy) in 1979. She obtained her PhD in applied Microbiology in 1982 and won scholarships to attend the Istituto Zooprofilattico Sperimentale del Mezzogiorno (Portici, Naples) and the National Research Council (Consiglio Nazionale delle Ricerche, Rome).
From 1983 to 1991, she was appointed researcher in Clinical Veterinary Medicine at the University of Messina.
In 1991, she became Associate Professor and in 2000 Full Professor at the same department. Since 2002, she is also Head of the Internal Medicine Clinic for Companion Animals at the same University. She has a particular interest in feline medicine, feline infectious diseases, clinical immunology and small animal arthropod borne diseases and is Board member of the Associazione Italiana Veterinari Patologia Felina (Italian Veterinary Study Group for Feline Diseases).
She is author or co-author of some 140 papers published in peer reviewed journals, book chapters, and is a frequent invited speaker at national and international congresses.