Electrophysiology and pathology evaluation of the Yucatan pig as a non-rodent animal model for regulatory and mechanistic toxicology studies

Abstract

Six male and six female Yucatan pigs were utilized to investigate the feasibility of this species as a non-rodent model for routine regulatory and mechanistic toxicology studies. This study evaluated disease surveillance and computerized electrophysiology, along with possible gross and micropathology changes. Two pigs were used as sentinel animals to evaluate the microbiological status of the vendor upon arrival; the other pigs were maintained as biomonitors and to provide baseline clinical chemistry, urinalysis, pathology and electrophysiology data. The electrophysiology tests conducted included electrocardiography (ECG), electroretinography (ERG) and quantitative electroencephalography (qEEG), which achieved consistent baseline values with acceptable intra subject variation. Tissue cholinesterase and histochemical staining were done to determine their suitability for testing cholinesterase compounds. Evaluation of the serum chemistry profile demonstrated increased CPK and LDH, which was likely associated with slight haemolysis or minor subclinical muscle stress during handling. There were no additional clinical chemistry changes or findings in haematology, urinalysis parameters or gross pathology. Micro pathology found an absence of background lesions which would interfere with routine toxicology studies, except for a mild rhinitis. The aetiological agent was identified by electron microscopy as being consistent with inclusion body rhinitis of swine, previously unreported in miniature swine. This would most notably interfere with inhalation studies. The anatomical and physiological similarities of the Yucatan pig, along with its ability to accept the performance of electrophysiology tests allow this species to be considered as a suitable model for organ system testing in toxicology studies.