Computed tomography is commonly utilized for investigation of rabbits, and more recently, for evaluating abdominal pathology. The spleen, however, is an often-overlooked organ, with limited information published. The aims of this retrospective, observational, study were to document the visibility, size, and shape of the normal rabbit spleen and potential correlations with signalment. Institutional imaging archives were reviewed for diagnostic-image-quality abdominal CT studies of rabbits. . In 115 cases, the inclusion criteria were met. Pre- and postcontrast CT studies were evaluated by two reviewers for visibility of the spleen. For precontrast CT images, the interrater agreement for identification of the spleen was fair. For postcontrast CT images, interrater agreement was moderate . There were significantly more spleens clearly identified on postcontrast studies compared with precontrast CT . Splenic location, volume, shape, X-ray attenuation, and length were measured, and the splenic-volume-to-body-weight ratio was calculated. The mean splenic volume was 1 mL (range 0.2-3.9 mL), mean length 40 mm (range 20-61 mm), mean attenuation (precontrast CT 80 HU and postcontrast CT 320 HU), and mean splenic volume/body weight ratio was 0.5 mL/kg (range 0.17-1.2 mL/kg). There was a significant relationship between splenic volume and body weight , which was weakly positively correlated . There was no correlation between splenic volume, age, and sex. The most commonly identified splenic shapes were "banana", "tongue", and "elephant trunk". The rabbit spleen can be identified on CT images, but more reliably on postcontrast CT images, which underlines the usefulness of contrast-enhanced CT in this species.

In 2022–2023, the first survey of clinicians regarding Encephalitozoon cuniculi infection of rabbits was undertaken. The purpose was to assess the current worldwide knowledge of clinicians regarding influence of breed and age, clinical presentations, use of various diagnostic tools, and treatment regimens and to explore how responses may differ by geographic location. Identifying mostly as exotic animal clinicians, 339 respondents participated, with nearly half from the United States and the remainder from 35 other countries. Neurological signs were most consistently reported as associated with Encephalitozoon cuniculi and the most recurrent clinical case presentation. Other responses showed differences by geographic location. For example, age predilection for disease varied, with 71.1% of international respondents indicating that infection was more common in young rabbits versus 28.9% who suggested it was more frequent in older rabbits. This was significantly different (p = 0.001) from the information from respondents from the United States, where 48.0% indicated that younger rabbits had an increased incidence versus 52.0% who indicated that older age increased occurrence. While some differences may be related to the practice composition and the training level of respondents, many responses were in alignment with the existing literature. Future inquiries should focus more on these discrepancies to aid in generating guidelines for the diagnosis and treatment of this infectious disease.

Members of the microsporidial genus Encephalitozoon have the capacity to infect both mammals and birds, and E. cuniculi is most commonly found in rabbits. With a seroprevalence ranging up to 85%, E. cuniculi can be a problem in pet rabbits as well as in food production and laboratory animal science. While most infections are likely subclinical, there are three main clinical presentations: neurological, renal, and ocular. Typical clinical signs including vestibular disease and phacoclastic uveitis may develop with initial or relapsing infection, while renal infection is usually progressive and associated with non-specific clinical signs. High-sensitivity/specificity ante mortem diagnostic options are lacking, and serological testing most often provides adjunct rather than definitive information such that physical examination and other diagnostics are used more so for ruling out other differentials and comorbidities, rather than confirming infection. In the veterinary community, treatment regimens are variable given the lack of thorough studies and a consensus. The aim of this document is to present the available literature to give a concise review of this organism and its infection of rabbits as well as to propose guidelines and protocols for diagnostics and treatment regimens. In addition, the current challenges and recommendations for further studies are discussed.