Management of Morbidity and Mortality in a New Zealand White Rabbit Model of Steroid-Induced Osteonecrosis of the Femoral Head

• Published in: Comparative medicine Vol. 71; no. 1; pp. 86 - 98
• Main Authors: Casey, Kerriann M, Gore, Felicity, Vilches-Moure, José G, Maruyama, Masahiro, Goodman, Stuart B, Yang, Yunzhi Peter, Baker, Samuel W
• Format: Journal Article
• Language: English
• Published: American Association for Laboratory Animal Science 01-02-2021
• Subjects: Case Studies
• ISSN: 1532-0820
• DOI: 10.30802/AALAS-CM-20-000071

Steroid-induced osteonecrosis of the femoral head (SONFH) is a condition documented in humans and animals exposed to chronic steroid administration. The rabbit has become a preferred animal model for investigating the pathogenesis and treatment of SONFH due to its shared femoral vascular anatomy with human patients, relative size of the femoral head, and general fecundity. However, morbidity and mortality are frequent during the steroid induction period, prior to surgical manipulation. These problems are poorly reported and inadequately described in the literature. In this study, we report the clinical, gross, and histopathologic findings of New Zealand white (NZW) rabbits undergoing the steroid induction phase of the SONFH model. Severe weight loss (>30%), lipemia, hypercholesterolemia, hyperglycemia, and elevations in ALT and AST were consistent findings across all rabbits, although these changes did not differentiate asymptomatic rabbits from those that became clinically symptomatic or died. Euthanized and spontaneously deceased rabbits exhibited hepatomegaly, hepatic lipidosis/glycogenosis, and hepatocellular necrosis, in addition to a lipid-rich and proteinaceous thoracic effusion. A subset of rabbits developed opportunistic pulmonary infections with
Bordetella bronchiseptica
and
Escherichia coli
and small intestine infections with
Lawsonia intracellularis
superimposed on hepatic and thoracic disease. Together, these findings allowed us to establish a clinical decision-making flowchart that reduced morbidities and mortalities in a subsequent cohort of SONFH rabbits. Recognition of these model-associated morbidities is critical for providing optimal clinical care during the disease induction phase of SONFH.