COMPARISON BETWEEN THORACIC RADIOGRAPHIC FINDINGS AND POSTMORTEM DIAGNOSIS OF THORACIC DISEASES IN DYSPNEIC COMPANION RATS (RATTUS NORVEGICUS)

Abstract

Companion rats are often presented to veterinarians for respiratory difficulties. Dyspnea in rats is most commonly due to infectious pneumonia, and thoracic neoplasia can go undiagnosed ante mortem due to a mistaken interpretation of pneumonia. In domestic carnivores, pulmonary nodular patterns have been shown to correlate with lung neoplastic diseases and infectious diseases. The main objective of this retrospective case series study was to determine whether certain radiographic criteria could be correlated with the presence of thoracic infectious disease and neoplastic disease in companion rats. A secondary objective was to determine whether the patient's sex and age were different between rats diagnosed with infectious versus neoplastic disease. Medical records and thoracic radiographs of dyspneic companion rats presented to the University of California at Davis, William R. Pritchard Veterinary Medical Teaching Hospital during the time period from January 2000 to December 2014 were reviewed. Rats with postmortem confirmation of thoracic lesions were included in the study. Thoracic radiographs were evaluated for positioning, lesion distribution, lung lobe involved, pulmonary pattern, mediastinal and pleural lesions by three observers blinded to diagnosis. Thirty rats were included in the study, including 23 rats with an infectious disease and seven with neoplasia. Mediastinal lesions were significantly more prevalent in the group diagnosed with thoracic neoplasia (P = 0.031), in particular cranially (P = 0.048). Although there was an overlap between the two groups, findings indicated that the presence of cranial mediastinal lesions may be helpful for differentiating neoplastic from infectious disease in rats.

Clinical presentation and treatment of lymphoma in companion rats (Rattus norvegicus; 2008–2020)

“…It is known that thoracic radiographs present limitations regarding the ability to differentiate between infection and neoplasia. 22 A previous study indicated that the presence of cranial mediastinal lesions on radiographs may be helpful to differentiate neoplastic from infectious disease in rats, although mediastinal lesions were often difficult to detect on radiographs in this study. 22 In case 6, a blood smear was obtained just prior to euthanasia, which would have resulted in antemortem diagnosis of lymphoid leukemia had the animal not been euthanized.…”

“…5,21 In a study evaluating rat thoracic radiographs in comparison with the postmortem diagnosis, lymphoma represented 72% of the neoplastic group, with lesions most commonly located in the cranial medias-tinum. 22 In this study, the radiographic interpretation was challenging and there were some difficulties differentiating pulmonary changes, cardiac changes, and mediastinal changes on radiographs. Additionally, some of the cases had evidence of suspected mediastinal change, such as widening, but no distinct mass noted.…”

The Rat Thoracic Ultrasound protocol: scanning technique and normal findings

“…It has been shown to improve procedural efficiency whilst decreasing complications, increasing success, and reducing financial strain ( 53 ). In the medical treatment of pet rats, the main advantage of RATTUS is the possibility of evaluating the thoracic wall without anaesthesia (in contrast to TXR or CT) ( 43 ). Due to the size of the thoracic cavity and the use of a linear probe, the examination is relatively quick and easily conducted.…”