Ultrasound and computed tomography of sacculitis and appendicitis in a rabbit

Computed tomographic features of the normal spleen in rabbits (Oryctolagus cuniculus domesticus)

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.

Safety of intravenous iodinated contrast medium injection in rabbits undergoing conscious computed tomography

Background

Contrast media in CT is widely used in dogs and cats to provide superior tissue delineation and increase the diagnostic capabilities. These contrast-enhanced imaging techniques are gaining popularity in rabbits; published studies reporting the safety of doing so are lacking.

Methods

This retrospective observational study aimed to determine the incidence of adverse events following the intravenous administration of iodinated non-ionic contrast medium in 350 rabbits. The medical records of this subset of rabbits admitted between January 2009 and November 2018, that underwent CT examination and received intravenous contrast media, were evaluated.

Results

From the 350 rabbits, 342 rabbits were still alive 7 days after the scan. A total of eight rabbits died within 7 days of the scan, seven of which within the first 24 h. All deaths were presumed to be sequelae to the diseases they were being investigated for and not thought to be related to the administration of intravenous contrast medium.

Conclusions

The results indicated that the use of intravenous non-iodinated contrast medium was well tolerated and safe in rabbits undergoing conscious CT examination.

Clinical, surgical, and pathological findings in client-owned rabbits with histologically confirmed appendicitis: 19 cases (2015-2019)

OBJECTIVE

To report clinical, surgical, and pathological findings in client-owned rabbits with histologically confirmed appendicitis.

ANIMALS

19 rabbits.

PROCEDURES

Medical records for client-owned rabbits that had a histologic diagnosis of appendicitis were reviewed.

RESULTS

Median age of the rabbits at presentation was 24.0 months (range, 4 to 84 months). Seventeen cases occurred during the summer and fall seasons. Decreased appetite (17/19 rabbits), abnormal rectal temperature (hyperthermia, 9/16 rabbits; hypothermia, 4/16 rabbits), hypocalcemia (8/11 rabbits), and hypoglycemia (7/15 rabbits) were common signs. Abdominal ultrasonography and CT findings were suggestive of appendicitis in 6 of 8 rabbits and in 1 of 2 rabbits, respectively. Of the 6 rabbits that received medical treatment, 3 died at 48 hours, 1 died at 24 hours after hospitalization, and 1 died at 10 days after presentation; 1 rabbit was alive at 1,030 days after presentation. Of the 8 rabbits that underwent appendectomy, 3 died before discharge from the hospital and 1 died 113 days after surgery; 4 rabbits were alive at 315, 334, 1,433, and 1,473 days after presentation. The remaining 5 rabbits either died or were euthanized before treatment could be instituted. In each of the 19 rabbits, the appendix had evidence of severe inflammation with mucosal ulceration, heterophilic inflammation, and necrotic debris.

CLINICAL RELEVANCE

For rabbits with decreased appetite and an apparently painful abdomen, hyperthermia, hypocalcemia, or hypoglycemia, appendicitis should be considered as a differential diagnosis. Further comparisons of medical and surgical treatments are required to establish treatment recommendations for rabbits with appendicitis.

Case Report: Spontaneous Appendicitis With Suspected Involvement of Klebsiella variicola in Two Pet Rabbits

Although laboratory rabbits are commonly used as models of appendicitis in man, spontaneous appendicitis was only described ante-mortem in one pet rabbit with an acute abdomen. The aim of this article is to describe two spontaneous cases of appendicitis in pet rabbits, to describe therapeutic appendectomy, and to discuss the microbial flora of the inflamed appendix. A 5-month-old intact female and a 16-month-old, neutered male were presented to the veterinary clinic with restlessness, anorexia, and reduced faecal output. The main clinical findings were restlessness, severe discomfort on abdominal palpation, a mid-abdominal palpable tubulous mass and an elevated rectal temperature. Blood analyses showed lymphocytosis, monocytosis, and hyperglycaemia. Radiography was inconclusive. Abdominal ultrasound revealed a presence of a tubular structure with wall thicknesses of 4.2 and 3.7 mm in the two rabbits, respectively. The tubular structure had a rounded, closed end, and a multilayered wall, suggestive of appendicitis. Due to metabolic acidosis and poor prognosis, the first rabbit was euthanized. In the 16-month-old rabbit, appendectomy was performed. Recovery was uneventful, and 4 h after surgery, the rabbit started to become normally active. Postoperative care consisted of fluid therapy, multimodal analgesia, supportive care and prokinetics. Follow-up examinations at 10 days, 1 month, and at 11 months after the surgery did not show any abnormal clinical or laboratory findings. Histopathological examination of appendices from both rabbits showed gangrenous appendicitis. Aerobic cultivation showed the presence of pure culture of Klebsiella variicola sensitive to enrofloxacin, marbofloxacin, tetracycline, cefuroxime, trimethoprim sulphonamide, neomycin, and gentamicin. Restlessness associated with anorexia, abdominal pain, palpable abdominal mass, hyperglycaemia, lymphocytosis, and elevated rectal temperature may be indicative of inflammation within the gastrointestinal tract. Abdominal ultrasound is recommended in rabbits with showing these clinical signs because radiography can be inconclusive. Appendicitis is a life-threatening condition, which should be included into the list of differential diagnoses; for the rabbit, an acute abdomen and gastrointestinal stasis syndrome and must be treated immediately. K. variicola may be associated with appendicitis in rabbits as a causative agent or in association with appendix intraluminal dysmicrobia.

Technological Advances in Surgical Equipment in Exotic Pet Medicine

Surgery can be challenging in exotic pets owing to their small size and blood volume, and their increased anesthetic risk compared with small animals. Various devices are available to facilitate suturing, cutting, and hemostasis in the human and veterinary fields. These surgical equipment improve the simplicity, rapidity, and effectiveness of surgery. Vessel-sealing devices, radiosurgery, lasers, and ultrasound devices are commonly used because of their ease of use and increase in surgical efficiency. Other surgical devices are available (eg, stapling devices) but are not discussed in this article.

Ultrasound morphology of cecal appendix in pet rabbits

PURPOSE

Cecal appendix is the terminal part of cecum and is characteristic of rabbit, among domestic animals. The purpose of this work is to evaluate its morphology upon ultrasound.

METHODS

A prospective study was planned for the duration of approximately 1 year. Rabbits presented in the study period for abdominal ultrasound with no clinically evident alterations of the gastrointestinal tract were eligible for inclusion in the study. Abdominal ultrasound was performed under manual restrain with a high frequency linear probe (8-18 MHz).

RESULTS

Cecal appendix was visualized in 40/42 rabbits (95.2%) with median or left paramedian views. The wall appeared multilayered in accordance with normal bowel anatomy, and the luminal content showed in all cases an alimentary pattern. Measurement of appendix wall thickness (AWT) was possible in all 40 rabbits in which the appendix was visualized while measurement of the appendix diameter (AD) was possible in 39 rabbits. Reference intervals for AWT were 1.1-2.1 mm, and for AD were 3.9-8.8 mm. There was a negative correlation between age and AWT (r = - 0.35, P = 0.027) and a moderate positive correlation between AWT and AD (r = 0.71, P < 0.001).

CONCLUSIONS

Cecal appendix is recognizable via ultrasound in the vast majority of rabbits. We describe the normal morphological aspect of the appendix and we provide reference intervals for wall thickness and diameter of the appendix, in order to aid in the diagnosis of disorders of the appendix. The negative correlation between age and AWT indicates lower values of AWT associated with increasing age that could represent the physiological decrease in the immunitary function of the appendix in aged rabbits.