Dr. David A Williams is a Professor of Veterinary Clinical Medicine at College of Veterinary Medicine, University of Illinois. He founded the "GI Lab" in 1985 at the University of Florida, when he introduced assay of serum trypsin-like immunoreactivity (TLI) in the dog to the United States. His research has been focused on the development and application of new tests for gastrointestinal diseases, particularly those affecting the pancreas, small intestine, stomach and liver of dogs and cats. Students and staff working in his subsequent GI Laboratories at Kansas State, Purdue, and most recently Texas A&M Universities established several other novel tests for gastrointestinal diseases for use by veterinarians internationally. These included feline serum TLI, canine and feline serum PLI, canine and feline fecal alpha 1 -proteinase inhibitor, unconjugated serum bile acids, canine TSH, and canine and feline serum cobalamin and folate assays. He received his veterinary degree from the University of Cambridge and his PhD from the University of Liverpool (where he first developed the canine TLI assay). He was an intern and resident at the University of Pennsylvania, and has held Faculty positions at the University of Florida, Kansas State University, Purdue University, Texas A&M University, and the University of Illinois, where he is presently Head of the Department of Veterinary Clinical Medicine. He continues to work as a consultant with the GI Lab, providing telephone consultations regarding management of patients diagnosed using the GI Lab services.

Dr. David A Williams's research interests are Development and application of new tests for gastrointestinal diseases, particularly those affecting the pancreas, small intestine, stomach and liver of dogs and cats.