Thymomas in Rabbits: Clinical Evaluation, Diagnosis, and Treatment

Abstract

Thymomas are rarely recorded in rabbits, and the literature includes comparatively few cases. Medical records were reviewed to identify all pet rabbits in which a mediastinal mass was diagnosed between Feb 2007 and Jan 2010. Signalment, history, clinical signs, diagnostic work-up (including laboratory data, diagnostic imaging, and ultrasound-guided fine-needle aspiration of the mediastinal mass), treatment modalities, survival time, and histologic findings were evaluated. Cytologic and/or histopathologic examinations revealed thymomas in all rabbits with mediastinal masses (n=13). Rabbits with thymomas showed clinical signs of dyspnea (76.9%), exercise intolerance (53.9%), and bilateral exophthalmos (46.2%). In seven rabbits the thymoma was removed surgically. Two rabbits were treated conservatively, and four rabbits were euthanized because of their poor clinical condition. The two rabbits that underwent surgery were euthanized 6 mo and 34 mo later. Mediastinal masses in rabbits appear to be more common than previously believed and consist primarily of thymomas rather than thymic lymphomas. Cytology of samples collected by ultrasound-guided fine-needle aspiration is an accurate diagnostic tool for the identification of thymomas in rabbits. Due to a high rate of perioperative mortality, intensive perioperative care and the provision of a low-stress environment are recommended for a successful thoracotomy.

Feasibility for Using Hypofractionated Stereotactic Volumetric Modulated Arc Radiotherapy (Vmat) With Adaptive Planning for Treatment of Thymoma in Rabbits: 15 Cases

“…Reported therapies for local control of thymoma in rabbits include surgery and radiation therapy. Regardless of the surgical approach, surgery for thymoma in rabbits is associated with a reported mortality rate of up to 71% in the perioperative period . The reported clinical signs on presentation including dyspnea, exopthalmos and anorexia are consistent with what has been previously reported in the literature .…”

“…They are generally slow growing with the potential for local invasion and only rarely metastasize . Reported therapies include surgery, radiotherapy, and adjuvant chemotherapy . While most of these studies are case reports one study evaluated 19 rabbits that received various radiotherapy protocols treated at multiple institutions, with a reported median overall survival of 313 days .…”

“…In this study, three rabbits died acutely during the course of radiotherapy on the day of anesthesia and two developed radiotherapy side effects including radiation pneumonitis and myocardial necrosis . In most of the previously reported cases, conventional radiotherapy planning techniques were used although a few cases were treated with intensity modulated radiotherapy (IMRT) …”

T-lymphocyte-rich Thymoma and Myasthenia Gravis in a Siberian Tiger (Panthera tigris altaica)

“…Spontaneously-occurring thymomas have been reported in a range of domestic animals including dogs and cats (Day, 2008), cattle (Ecco et al. , 2006), rabbits (Kunzel et al. , 2012) and goats (Hadlow, 1978) as well as in various laboratory primates and rodents (Walsh and Poteracki, 1994; Brandes et al.…”

Thymom - ein unterdiagnostiziertes klinisches Problem beim Kaninchen?

“…Zum Thema Thymome beim Kaninchen dominieren in der Literatur lediglich Fallberichte [2,3,6,10,11]. In den letzten Jahren wurden einige retrospektive Studien, die in erster Linie verschiedene Therapiemaßnahmen des Thymoms beim Kaninchen beinhalten, publiziert [1,[7][8][9].…”