About Us

Tox Path Specialists, LLC was founded in July 2007 to provide preclinical neuropathology and neurohistology support to companies and other institutions developing neuroactive pharmaceuticals, devices, and other therapies, with emphasis on therapies delivered directly to the central and peripheral nervous systems.


Our team of experts also conduct morphometric and stereologic investigations of the brain, spinal cord, peripheral nerves and dorsal root/sympathetic ganglia, and coordinates these efforts into a larger anatomic pathology effort.



Click here to see more about our pathology services.


Dr. Mark Butt, DVM

President, Neuropathologist


The President and Chief Scientific Officer of Tox Path Specialists is Mark T. Butt, DVM, Diplomate, American College of Veterinary Pathologists. Dr. Butt has more than 20 years of experience evaluating the nervous system in a wide variety of laboratory species. Prior to founding Tox Path Specialists, Dr. Butt was a neuropathologist and manager for the Frederick, MD division of Charles River Laboratories [formerly Pathology Associates (PAI)] for 13 years, and for the last six of those years, was the General Manager with full financial and professional oversight of an organization with over 200 employees and 35 veterinary pathologists.


As the principal investigator/study neuropathologist of over 500 preclinical investigations, Dr. Butt consults with numerous global pharmaceutical and pathology companies and is a regulatory consultant on matters concerning the nervous system. For his expertise in neuropathology, he is a frequent speaker at national/international meetings, educational symposiums, and FDA sponsored events. Click here to view Dr. Butt's resume.


Dr. Sarah Cramer, PhD, DVM

Senior Research Pathologist


Dr. Cramer joined Tox Path Specialists in 2016 after completing PhD training in the laboratory of Dr. Scott Durum with the Comparative Biomedical Scientist Training Program, a graduate partnership program between the National Institutes of Health, National Cancer Institute, and University of Maryland Department of Veterinary Medicine. Prior to this, Dr. Cramer completed a residency in veterinary anatomic pathology at Oklahoma State University and earned a Doctor of Veterinary Medicine from Cornell College of Veterinary Medicine. 

Beth Taylor

Research Associate


Bridgette Glass

Research Associate





Click here to see more about our histology services.


Dave Hodge, HT (ASCP)

Director of Laboratory Services


TPS houses a laboratory with full general histology and specific neurohistology capabilities. Our laboratory is headed by Dave Hodge, HT (ASCP) with over 25 years experience in histology and laboratory management. Mr. Hodge has extensive experience as the director of histology laboratories.

The laboratory at Tox Path Specialists provides a wide range of neurohistology services: frozen, paraffin and resin-embedded sections, numerous special stains, and a range of morphometric/stereologic services. We specialize in complex and in-depth trimming procedures for tissues/specimens not typically harvested in the course of a preclinical study. Glial and neuronal immunohistochemical markers, stains to detect neuronal necrosis, and other specialized tissue processing methods, are all a part of our histopathology specialty.

Quality Assurance

Laura Caccese

Director of Quality Assurance


TPS is a fully GLP-compliant facility and maintains an in-house Quality Assurance Unit which monitors our facility for GLP-compliance. In addition to general facility inspections, each GLP study is monitored to ensure that the facility, equipment, personnel, methods, records, and controls comply with FDA 21 CFR Part 58 through a series of study-specific inspections including an in-process critical phase inspection, inspection of laboratory data, and inspection of the final pathology report. The QAU provides a quality assurance statement at the completion of the final pathology report or study phase completion, detailing the quality assurance activities that have taken place during the study phase at TPS.


Jake Butt

Director of Research and Development


Susan Butt

Director of Operations


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