ArticlePDF Available

Ultrasound and computed tomography of sacculitis and appendicitis in a rabbit

February 2018
Veterinary Radiology & Ultrasound 59(5)

DOI:10.1111/vru.12602

License
CC BY 4.0

Authors:

Maurizio Longo

University of Milan

Florence Thierry

University of Edinburgh

Show all 6 authorsHide

A 9-month-old neutered male rabbit was referred for lethargy, anorexia, and gastrointestinal stasis. Routine hematology, serum biochemistry, and diagnostic imaging were performed. Computed tomography revealed a wall thickening of the sacculus rotundus and appendix, which was further confirmed on abdominal ultrasound. Full thickness biopsies were collected with histopathology diagnosing a chronic multifocal heterophilic granulomatous sacculitis and appendicitis. The patient was treated medically and at 6 weeks follow-up, clinical signs and intestinal changes had completely regressed. Inflammation of the sacculus rotundus and appendix should be considered as a cause of gastrointestinal stasis in rabbits.

Available via license: CC BY 4.0

Content may be subject to copyright.

Received: 10 August 2017 Revised: 9 October 2017 Accepted: 31 October 2017

DOI: 10.1111/vru.12602

IMAGING DIAGNOSIS

Ultrasound and computed tomography of sacculitis

and appendicitis in a rabbit

Maurizio Longo Florence Thierry Kevin Eatwell Tobias Schwarz Jorge del

Pozo Jenna Richardson

Royal (Dick) School of VeterinaryStudies and

Roslin Institute, The University of Edinburgh,

Roslin, UK

Correspondence

Maurizio Longo, Royal (Dick) School of Veteri-

nary Studies and Roslin Institute, The University

of 7 Edinburgh, Roslin, EH25 9RG, UK.

Email: mlongo@exseed.ed.ac.uk

Abstract

A 9-month-old neutered male rabbit was referred for lethargy, anorexia, and gastrointestinal sta-

sis. Routine hematology, serum biochemistry, and diagnostic imaging were performed. Computed

tomography revealed a wall thickening of the sacculus rotundus and appendix, which was fur-

ther confirmed on abdominal ultrasound. Full thickness biopsies were collected with histopathol-

ogy diagnosing a chronic multifocal heterophilic granulomatous sacculitis and appendicitis. The

patient was treated medically and at 6 weeks follow-up, clinical signs and intestinal changes had

completely regressed. Inflammation of the sacculus rotundus and appendix should be considered

as a cause of gastrointestinal stasis in rabbits.

KEYWORDS

appendix, cecum, sacculus rotundus, typhilitis

1SIGNALMENT, HISTORY, AND CLINICAL

FINDINGS

A 9-month-old, male neutered, Lionhead rabbit was presented to the

Rabbit and Exotic Animal Department at the referral Hospital of the

University of Edinburgh for evaluation of a 4-day history of anorexia,

lethargy, and decreased fecal production consistent with gastrointesti-

nal stasis. The patient was neutered at 6 months of age by the refer-

ring veterinary surgeon and had no previous health concerns. The diet

offered included ad-libitum hay, with a small ration of complete com-

mercial pellet and mix of fresh green vegetables each day.

On physical examination, the patient was tachypnoeic, with a heart

rate of 200 beats/min and an elevated rectal temperature of 39.9◦C.

Body condition score was 2/5 and no abnormality was detected

on palpation of the abdomen. Gut sounds were absent on abdominal

auscultation. Complete blood count findings included a mildly elevated

white cell count of 13.1 ×109/l (reference range 5.2–12.5 ×109/l)

with left shift of the neutrophils. The patient was medically managed

with supportive care for 24 h including intravenous fluid therapy with

compound sodium lactate (Hartmann's solution, Aquapharm, Animal-

care Limited, UK) at 4 ml/kg/h divided into slow intravenous boluses.

Multimodal analgesia was provided with buprenorphine (Buprecare

[The copyright line for this article was changed on 5 March 2018 after original online publication.]

This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided

the original work is properly cited.

2018 The Authors. Veterinary Radiology & Ultrasound published by Wiley Periodicals, Inc. onbehalf of American College of Veterinary Radiology

0.3 mg/ml, Animalcare Limited, UK) at 0.03 mg/kg subcutaneously

every 6 h alongside a nonsteroidal anti-inflammatory drug, meloxicam

(Metacam 1.5 mg/ml, Oral Suspension, Boehringer Ingelheim, Ger-

many) at 0.6 mg/kg per every 12 h. Gastrointestinal prokinetic therapy

was provided with ranitidine (Zantac 15 mg/ml, GlaxoSmithKline, UK)

at 4 mg/kg per os every 12 h and cisapride (Cisapride 5 mg/ml, Summit,

UK) at 0.5 mg/kg per os every 12 h. Assisted feeding with an herbivore

critical care food (Critical Care Herbivore, Oxbow Animal Health,

USA) 25 ml was provided per os every 4 h.

2IMAGING FINDINGS, DIAGNOSIS,

AND OUTCOME

To investigate causes of gut stasis, a helical-64-slice whole body

computed tomographic (CT) study (Somatom Definition AS Siemens,

Erlangen, Germany) was performed without sedation, and with

restraint provided by a VetMouseTrap (Universal Medical Systems

Inc, Solon, USA). Scan settings included a pitch of 1.5, tube potential

of 120 kVp, reference tube current of 160 mA, slice thickness of

1.5 mm, matrix 512 ×512, and reconstruction with low and high fre-

quency algorithms. Scan tube current was modulated by an automatic

Vet Radiol Ultrasound. 2018;1–5. wileyonlinelibrary.com/journal/vru 1

2LONG O ET AL.

FIGURE 1 Postcontrast computed tomographic image of the sacculus rotundus (*) and appendix (arrowhead) in transverse (A) and dorsal plane

(B). B-mode ultrasound image of the sacculus rotundus (C) (8 MHz, wall thickness 0.8 cm), with anechoic and gas content, and of the appendix (D)

(14 MHz, wall thickness 0.6 cm) showing multifocal mucosal speckles and thickened wall (between callipers) [Correction added on 5 March 2018

after first online publication: the position of figures 1 and 2 have been reversed in the text. They were originally published out of order and with

incorrect captions.]

exposure control system (Care Dose 4D, Siemens Medical Solutions,

International). Postcontrast images were acquired within 1 min after

contrast injection and reconstructed with a low frequency algorithm.

A bolus of 740 mg Iodine/kg of nonionic iodinated contrast medium

(Iopamiro, Bracco, Manno, Switzerland) was manually injected through

an auricular angiocatheter followed by 1.5 ml of saline solution flush.

On postcontrast images, a round fluid-filled structure delineated by

a contrast-enhancing wall was detected in the right caudoventral

abdomen along the lesser curvature of the cecum (Figure 1A and B).

This saccular structure contained a small amount of gas and its lumen

projected into the cecal lumen, which was consistent with the location

of the sacculus rotundus. Its wall was markedly thickened (0.77 cm).

Within the left mid-ventral abdomen, an elongated and thickened

(wall thickness 0.4 cm, Figure 1A and B) blind-ending tubular structure

was visible connected to the cecum, consistent with the appendix.

Mild peritoneal effusion and moderate mesenteric lymphadenopathy

(1.2 cm in width) were also identified. The presumptive CT diagnosis

was sacculitis and appendicitis, with associated reactive local lym-

phadenopathy and mild inflammatory peritoneal effusion. Abdominal

B-mode ultrasound was performed (MyLab Twice Esaote, Genova,

Italy) with microconvex (SC 3123) and electronic linear (LA 435) array

probes, with frequencies ranging between 8–14 MHz. Ultrasound

examination confirmed the markedly thickened wall of the sacculus

rotundus (0.8 cm) located dorsal to the cecum, without loss of wall

layering (Figure 1C). A distinct inner mucosal layer was detected, how-

ever heterogeneously hyperechoic and markedly thickened, while the

outer layer was hypoechoic (Figure 1C). Moreover, the appendix had a

moderately thickened wall (0.6 cm) containing numerous hyperechoic

speckles (Figure 1D). At this stage, an inflammatory noninfectious or

infectious sacculitis and appendicitis was suspected, while neoplastic

infiltration was considered less likely due to the extension of the

infiltration and the young age of the animal. Considering the ongoing

anorexia, with lack of response to medical treatment and the high risk

of dysbiosis, an exploratory laparotomy was recommended.

LONG O ET AL.3

FIGURE 2 Intraoperative picture of the appendix (arrow) and sacculus rotundus (asterisk) (A). Histological presentation of the appendix, with

multifocal necrotic granulomas (B, scale bar =1000 𝜇m, Hematoxylin & Eosin). Intraoperative picture of the multifocal wall microabscesses visible

at the level of the appendix (C). Appendix granuloma with necrotic core, a rim of macrophages and neutrophils (D, scale bar =50 𝜇m, Hematoxylin

& Eosin) [Correction added on 5 March 2018 after first online publication: the position of figures 1 and 2 have been reversed in the text. They were

originally published out of order and with incorrect captions.]

At surgery, the segmental thickening was confined to both the sac-

culus rotundus and appendix, with no evidence of wall defect (Fig-

ure 2A and C). Multifocal micro-abscesses were spread throughout

the wall (Figure 2A and C). Full thickness biopsies were taken from

the sacculus rotundus and appendix walls. A firm, pedunculated, irreg-

ular nodule extending into the sacculus rotundus lumen was also

excised. Samples were sent for bacteriology and histopathology. Cul-

ture of the biopsied tissues was negative for specific fungal or bacte-

rial growth, but rather a light, mixed bacterial growth with no predom-

inant organism was identified at the level of the appendix (nonspecific

growth). On histopathology, multifocal, 500–2000 𝜇m wide, round to

oval lesions were scattered in the submucosa of the sacculus rotun-

dus and appendix (Figure 2B and D). These lesions had a large, central

area of lytic necrosis, with loss of cellular detail, hypereosinophilia, and

accumulation of cytoplasmic and nuclear debris. Around the necrotic

core, there was a poorly defined, thick rim of infiltration by large num-

bers of macrophages, with very rare bi-nucleated forms and scattered

neutrophils. The gut-associated lymphoid tissue was diffusely promi-

nent (lymphoid hyperplasia). There was moderate diffused infiltration

of the lamina propria by lymphocytes and plasma cells, and there was

trans-epithelial transmigration of the mucosal epithelium by small to

moderate numbers of heterophils. This presentation led to a histo-

logical diagnosis of severe, chronic, multifocal granulomatous sacculi-

tis, and appendicitis with necrotic heterophilic granuloma formation.

Warthin Starry (silver) and Ziehl Neelsen stains did not reveal specific

infectious agents, and bacterial infection was considered a possible dif-

ferential diagnosis.

Supportive treatment was continued, and additional oral antibi-

otics with trimethoprim sulphate (Sulfatrim 96 mg/ml, Virbac, UK) at

15 mg/kg per os every 12 h and metronidazole (200 mg/5ml, Lexon,

UK) at 20 mg/kg per os every 12 h, were added to the previous

medical therapy. The patient recovered uneventfully from surgery,

with normal gut sounds within 24 h and was discharged after 48

h. At 5 days postdischarge, the owner reported progressive return

to spontaneous eating and normal defecation. At 4 weeks follow-up,

complete regression of the clinical signs was obtained and complete

blood counts were within normal limits. A follow-up abdominal ultra-

sound revealed a moderate decrease in wall thickness of the sacculus

4LONG O ET AL.

rotundus (0.56 cm), although a focal heterogeneous area most likely

consistent with the previous biopsy site was detected. The appendix

appeared partially evaluable and gas-filled. At 6 weeks ultrasono-

graphic follow-up, the wall of the sacculus rotundus (0.3 cm) and

appendix were markedly reduced in thickness, with normal wall layer-

ing and echogenicity.

3DISCUSSION

This case highlights the important roles of CT and ultrasound as com-

plementary modalities for investigating gut stasis in rabbits. Presump-

tive sacculitis and appendicitis was diagnosed on CT based on focal

wall thickening of a saccular structure connected to the cecum. To the

authors’ knowledge, the CT appearance of the sacculus rotundus and

appendix has never been described in the veterinary literature. More-

over,only a single old reference describing the presence of granuloma-

tous appendicitis in rabbits was found.1

Further ultrasonographic examination of the abdomen provided

important additional information confirming the exact location and

nature of the lesion, affecting both the sacculus rotundus and the

appendix. In this patient, the wall thickening of the appendix and saccu-

lus rotundus measured more than twice the normal limits reported on

ultrasound.2Furthermore the diffuse thickening, preserved layering,

and mucosal speckles prompted the presumptive diagnosis of inflam-

matory or infectious disease. A neoplastic process, such as round cell

tumor, was considered less likely because of the young age of the

patient and extensive intestinal infiltrative changes without loss of

wall layering. As previously reported in cats, abnormalities detected on

ultrasonography or endoscopy at the levelof the ileocecocolic junction

should encourage histology for further evaluation. Histopathology was

performed in this case to confirm the imaging diagnosis.3

Due to the lack of information in the literature on the normal CT

appearance of the sacculus rotundus and appendix, ultrasonography

was a crucial complementary tool to confirm the nature of the lesion.

Both structures are small and challenging to detect on B-mode abdom-

inal ultrasound. They can be located in the mid-ventral abdomen at

the level of the umbilical region; however, the proximity of the cecum

hinders identification of these structures due to the distal acoustic

shadowing and gas reverberation from the adjacent cecal content. In

a previous study of 21 healthy mixed-breed dwarf rabbits, the saccu-

lus rotundus was detected in 14/21 patients, while the appendix was

always visible.2In the authors’ experience, the location of the saccu-

lus rotundus on CT is similar in most rabbits in the right caudoventral

abdomen along the lesser curvature of the cecum and it remains visible

in most of animals, while a normal appendix is often more challenging

to identify.

The rabbit cecum is a highly developed and differentiated organ,

compared to the cecum of other species, such as dogs and cats.4–7

The sacculus rotundus is an ampullar distension of the intestine rep-

resenting the distal end of the ileum, located on the first haustral-like

pouch of the corpus ceci. The appendix is located at the caudal tip

of the cecum, similar to humans.8–11 In Angora rabbits, the sacculus

rotundus is described to have a thick wall with a wide lumen, short

thick villi, large amount of crypts, and numerous lymphoid follicles.5

Moreover, on histopathology it differed from other parts of the diges-

tive system and was considered a novel lymphoid organ, because of

its high dense lymphoid accumulation.5,11 The ‘vermiform’ appendix of

the rabbit plays a fundamental role for development of the primary

(preimmune) antibody repertoire. It partially atrophies with age in this

species however it is fundamental for the immunological development

of gut-associated lymphoid tissues.11

Despite representing one of the most common surgical diseases in

children, to the authors’ knowledge, spontaneous sacculitis and appen-

dicitis in rabbits has only been reported once before.12,13 A previous

old publication described the histopathological findings in 25 with

rabbits affected by granulomatous appendicitis, with similar findings in

the sacculus rotundus.1In a more recent publication, an experimental

model of appendicitis was created by ligating the appendix of rabbits

in view of measuring blood markers of acute appendicitis.14 Medical

treatment is commonly included as a suitable alternative in humans

in nonacute and nonperforated cases of appendicitis.3In the rabbit

of this case report, the clinical signs of gastrointestinal stasis and

anorexia were believed to be secondary to the disease. This was

further supported by the prompt response to medical treatment

postsurgical diagnostic biopsies and the complete regression of clinical

and ultrasonographic abnormalities 6 weeks after diagnosis.

The authors speculate that the presence of intramural microab-

scesses is supportive of a potential infectious process as the trigger

of the inflammation. Despite specific stains, no infectious agents were

identified, and culture yielded a light mixed growth, but no specific

prominent organism. A bacterial cause was considered a possibility

given the biopsy results, pyrexia, and neutrophilia. Clostridiosis was

highly unlikely due to the atypical localization of the lesions and lack

of necrohemorrhagic lesions.

In conclusion, granulomatous sacculitis and appendicitis should be

included among the potential causes of gastrointestinal stasis in rab-

bits. In the authors’ opinion, the sacculus rotundus and appendix

should always be assessed during CT or ultrasonographic abdominal

examinations of the rabbit, especially in young patients presenting for

gastrointestinal stasis.

LIST OF AUTHOR CONTRIBUTIONS

Category 1

(a) Conception and Design: Longo M, Thierry F, Richardson J,

Schwarz T

(b) Acquisition of Data: Longo M, Thierry F, Richardson J, Eatwell

K, Pozo Jd

Eatwell K, Schwarz T, Pozo Jd, Richardson J

Category 2

(a) Drafting the Article: Longo M

(b) Revising Article for Intellectual Content: Longo M, Thierry F,

Eatwell K, Schwarz T, Pozo Jd, Richardson J

Category 3

(a) Final Approval of the Completed Article: Longo M, Thierry F,

Eatwell K, Schwarz T, Pozo Jd, Richardson J

LONG O ET AL.5

ACKNOWLEDGMENT

The authors would like to thank Dr. Emma Keeble for her kind assis-

tance with the case.

ORCID

Maurizio Longo http://orcid.org/0000-0002-6838-8430

Florence Thierry http://orcid.org/0000-0003-4175-4397

REFERENCES

1. Fujiwara H, Uchida K, Takahashi M. Occurrence of granulomatous

appendicitis in rabbits. Jikken Dobutsu. 1987;36:277–80.

2. Banzato T, Bellini L, Contiero B, Selleri P, Zotti A. Abdominal ultra-

sound features and reference values in 21 healthy rabbits. Vet Re c.

2015;176:101.

3. Hahn H, Pey P, Baril A, et al. Ultrasonographic, endoscopic and histo-

logical appearances of the caecum in cats presenting with chronic clin-

ical signs of caecocolic disease. J Feline Med Surg. 2017;19:94–104.

4. Snipes RL. Anatomy of the rabbit cecum. Anat Embryol (Berl).

1978;155:57–80.

5. Besoluk K, Eken E, Sura E. A morphological and morphometrical study

on the sacculus rotundus and ileum of the Angora rabbit. Vet Me d.

2006;51:60–65.

6. Harriet H, Freiche V, Baril A, et al. Ultrasonographic, endoscopic and

histological appearance of the caecum in clinically healthy cats. JFeline

Med Surg. 2017;19:85–93.

7. Barone R. Intestine. In: Barone R, ed. Comparative Anatomy of Domestic

Mammals. Tome 3. Splanchnology. Paris: Vigot; 1997:385.

8. Snipes RL. Anatomy of the rabbit cecum. Anat Embryol. 1978;1:57–80.

9. Lord C, Broadhurst J, Sleight S, McGee S, Wills M. The appendix: A

spectrum of benign and malignant disease. Br J Hosp Med. 2017;78:82–

87.

10. Popesko P, Rajtová V, Horák J. A Colour Atlas of Anatomy of Small Labo-

ratory Animals. Vol 1. Philadelphia: Saunders; 2002:p91.

11. Dasso JF, Obiakor H, Bach H, Anderson AO, Mage RG. A morphologi-

cal and immunohistological study of the human and rabbit appendix for

comparison with the avian bursa. Dev Comp Immunol. 2000;24:797–

814.

12. López JJ, Deans KJ, Minneci PC. Nonoperative management of appen-

dicitis in children. Curr Opin Pediatr. 2017;29:358–362.

13. Adolph VR, Falterman KW. Appendicitis in children in the managed

care era. JPediatrSurg. 1996;31:1035–1036.

14. Katz E, Hana R, Jurim O, Pisuv G, Gutman A, Durst AL. Experimental

model of acute appendicitis in the rabbit with determination of leucine

amino peptidase (LAP) and acid phosphatase (acid-P) activities in por-

tal blood samples. JSurgRes. 1990;48:230–236.

How to cite this article: Longo M, Thierry F, Eatwell K, Schwarz

T, Pozo Jd, Richardson J. Ultrasound and computed tomography

of sacculitis and appendicitis in a rabbit. Vet Radiol Ultrasound.

2018;1–5. https://doi.org/10.1111/vru.12602

Computed tomographic findings of the gastrointestinal tract in rabbits (Oryctolagus cuniculus)

Article

Mar 2022
J EXOT PET MED

Background Gastrointestinal (GI) diseases are common in rabbits. Although diagnostic imaging studies can assist clinicians in selecting therapeutic approaches, there are few reports of advanced imaging findings in normal rabbits. Computed tomography (CT) is recognized as a useful tool in dogs and cats, but there are few reports of normal findings on multidetector computed tomography (MDTC) in rabbits. The goals of this study are to describe the CT anatomical imaging appearance of the GI tract and their normal variation in healthy pet rabbits and to obtain the normal wall thickness measurements of normal GI tract structures. Methods Twenty-three rabbits were scanned under general anesthesia and the CT abdominal images were analyzed by two experienced radiologists. Location and size of the major GI organs and structures were determined, and wall thickness of the stomach, small and large intestines were measured, including the interobserver agreement. Statistical analysis of quantitative and qualitative variables were performed. Results Wall thickness values were established for the different parts of the stomach (cardia: 3.4 ± 0.4mm; fundus: 1.4 ± 0.2mm; body: 1.4 ± 0.1mm; pylorus: 2.9 ± 0.5mm), small intestines (duodenum: 1.4 ± 0.1mm; jejunum: 1.2 ± 0.1mm; ileum: 1.4 ± 0.1mm), and large intestines (cecum: 1.2 ± 0.1mm; colon ascending: 1.4 ± 0.3 mm and descending: 1.3 ± 0.3mm). When distended the stomach did not extend beyond the caudal limits of the L2 vertebra. The cecum occupied the ventral abdominal region from T12/T13 to L7/S1, the sacculus rotundus was identified in 11 of the 23 rabbits. The sacculus rotundus and vermiform cecal appendix were identified only in rabbits with mild large intestinal distension. Conclusions and clinical relevance It was possible to use CT to evaluate the different portions of the GI tract that are not normally readily visible on radiographs and ultrasound (US). Normal wall thickness values of the different portion of the GI tract were stablished. These results provide new and important reference values for CT studies in normal pet rabbits and provide data for further studies in rabbits with GI diseases.

Sectional Anatomy with Micro-Computed Tomography and Magnetic Resonance Imaging Correlation of the Middle and Caudal Abdominal Regions in the Syrian Hamster (Mesocricetus auratus)

Article

Full-text available

May 2025

The abdomen is a key region in small animal veterinary practice, with the middle and caudal sections housing various organ systems that are susceptible to dysfunction, necessitating medical intervention or surgery. Sectional imaging techniques like CT and MRI are commonly used in small mammals, but no studies have focused on rodent abdomen. This study aimed to correlate micro-CT and MRI images of the middle and caudal abdominal regions with corresponding anatomical sections in Syrian hamsters (SHs), which are popular pets and experimental models. Ten healthy male SHs were used, and anatomical structures from frozen sections were compared with corresponding MCT and MRI images. Clinically relevant structures identified in anatomical sections were discernible on MCT and MRI scans. The key findings include the presence of glandular and non-glandular stomachs, the stomach and cecum primarily located on the left side, the absence of ampulla coli, sacculus rotundus, and cecal appendix, and sacculation of the colon, as well as the jejunum, mainly on the right side. The vesicular, coagulating, and prostate glands were also present, and the right kidney did not extend to the last thoracic vertebra. The results were similar to abdominal anatomical and radiologic studies in rats, mice, and guinea pigs, regardless of the rat’s and mice’s sacculated cecum and the guinea pig’s glandular stomach. However, significant differences were observed compared to the rabbit abdomen’s sectional anatomy and CT findings. This study highlights the diagnostic value of MCT and MRI in SHs and provides a valuable reference for interpreting cross-sectional abdominal images in SHs.

Evaluation of virtual non-contrast detector-based spectral CT images in comparison to true unenhanced images in 20 rabbits

Article

Full-text available

Mar 2025

Introduction Spectral detector Computed Tomography (SDCT) enables generation of virtual non-contrast (VNC) images derived from a post-contrast scan, as previously investigated in healthy dogs. This technique is especially promising for awake scanned rabbits where motion between the pre- and the post-contrast scans makes comparison challenging. This study aimed to determine the reliability of VNC images for assessing abdominal organs in 20 rabbits by evaluating their qualitative and quantitative parameters compared to true unenhanced (TUE) images. Our hypothesis were that the VNC series would be comparable to TUE series and that the quality of the VNC images would be equal to or even superior to the native images. Methods Attenuation values of VNC and TUE series were assessed using a two one-sided t-test (TOST) and the signal-to-noise ratio was calculated for each ROI in the different series. Additionally, a qualitative assessment of the VNC images relative to TUE images was performed in consensus by a board-certified radiologist and a second year diagnostic imaging resident by evaluating the iodine subtraction, image quality and noise of VNC images based on a 5-point Likert scale. Results A total of 219 regions of interest (ROIs) where drawn in abdominal organs. 72.1% of the ROIs displayed differences of less than 15 Hounsfield Units (HU) between TUE and VNC images. The differences in attenuation values of TUE and VNC were statistically significant (p < 0.05) for ≤ 5 HU in the spleen, for ≤ 10 HU and ≤ 15 HU additionally in the liver, musculature and renal cortices. These findings support the equivalence between VNC and TUE images. An average score of 4.4 was achieved for iodine subtraction across all patients, which encompasses all organ values, with no individual patient scoring below 4.0. Discussion VNC images present a promising alternative to TUE images for abdominal organs without pathology in rabbits with the benefit of eliminating motion between the compared series and reducing examination time and radiation exposure by replacing pre-contrast scans. Further research is necessary to demonstrate the applicability of the technique to morphologically diseased organs.

Rabbit Gastroenterology

Article

Dec 2024
Vet Clin Exot Anim Pract

Appendizitis beim Kaninchen – eine Erkrankung auf dem Vormarsch?

Article

Sep 2024

Anja Böttcher

The use of a focussed abdominal ultrasonographic technique in sick rabbits: Five cases

Article

Apr 2024

Sarah A. Band

A focussed abdominal ultrasonographic imaging technique was evaluated in five rabbits. Five sick rabbits presented to a veterinary exotics centre were imaged using a rapid, focussed ultrasonographic technique via four acoustic windows, as part of the clinical investigation. During imaging, the rabbits were either fully conscious, or sedated with midazolam if they showed signs of stress. Appendicitis, megacolon, splenic pathology and an intestinal wall abscess were identified using this technique, the diagnosis being confirmed on laparotomy, histopathology or computed tomography. A liver lobe torsion was suspected in one case, with supporting evidence from subsequent monitoring and response to medical management. This rapid ultrasonographic technique identified abnormal abdominal organs providing valuable diagnostic information, without the need for profound sedation or causing undue stress to the patient, demonstrating the potential value of focussed imaging in this species.

Advanced Imaging of Small Mammals

Article

Jul 2024

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

Article

Jul 2023
VET RADIOL ULTRASOUN

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.

Diagnosing and treating appendicitis in rabbits

Article

Jun 2023

Background: Appendicitis in rabbits is rarely described but is part of the differential diagnosis of acute and chronic gastrointestinal disorders in rabbits, and should be suspected as a priority in cases of hyperthermia. Imaging such as ultrasound or CT scan are essential for the diagnosis and should be included systematically in the exploration of gastrointestinal stasis syndrome. Treatment of such cases can be medical and/or surgical. It is important that practitioners understand the pathology, know when to suspect it and that they are able to select appropriate diagnostics to guide therapeutic management of these cases. Aim of the article: This article reviews cases of appendicitis in rabbits described in the literature and provides clinicians with the most up‐to‐date information on this condition.

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

Article

Full-text available

Mar 2022

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.

A morphological and morphometrical study on the sacculus rotundus and ileum of the Angora rabbit

Article

Full-text available

Feb 2006

The aim of this study was to reveal morphological and morphometrical properties of the sacculus rotundus (SR) and ileum in the Angora rabbit. For this purpose, a total of thirteen adult healthy Angora rabbits of both sexes were used. At the level of the junction of the ileum and SR, the ileum invaginated into the SR by protruding in 9 Angora rabbits, but joined directly the SR in 21. Numerous aggregate lymph follicles located just under the tunica serosa formed outstanding macroscopic polygonal areas on the external surface of the SR. In the inner wall of the SR, irregular projections were seen grossly. The saccorotundocecal orifice was found to be bordered laterally by two folds facing the cecum. These folds enclosed small polygonal spaces with mushroom shaped protrusions. The mean lengths and weights of SR and ileum in male were larger than those in female, and the related values also had statistical significance ( P < 0.05). Compared with the ileum, the SR had short and thick villi, had a large amount of crypts and aggregated lymphoid follicles, and had a much thicker wall and much wider lumen. The crescent- like-hollows were detected between the lamina propria and the apical portions of the lymph follicles. The results from this study are thought to shed light on future studies on the digestive system and proper diagnosis of pathological disorders related to it in the Angora rabbit, and to contribute to the present morphological knowledge on the SR and ileum in this species.

Ultrasonographic, endoscopic and histological appearance of the caecum in clinically healthy cats

Article

Full-text available

Aug 2015
J FELINE MED SURG

The aim of the study was to describe the ultrasonographical and endoscopic appearance and characteristics of the caecum in asymptomatic cats, and to correlate these findings with histology. Ex vivo ultrasonographical and histological evaluations of a fresh caecum were initially performed. Then, 20 asymptomatic cats, privately owned or originating from a reproductive colony, were included. All cats had an ultrasonographical examination of the ileocaecocolic junction, where the thickness of the caecal wall, ileocolic lymph nodes and the echogenicity of the local fat were assessed. They all underwent a colonoscopy with a macroscopic assessment of the mucosa and biopsies for histology. An ultrasonographical hypoechoic nodular inner layer, which corresponded to the coalescence of multiple lymphoid follicles originating from the submucosa and protruding in the mucosa on histology, was visible in all parts of the caecum. The combined mucosa and submucosa was measured ultrasonographically and defined as the follicular layer. Although all cats were asymptomatic, 3/19 cats showed mild caecal inflammation on histology. The most discriminant ultrasonographical parameter in assessing this subclinical inflammation was the thickness of the follicular layer at the entrance of the caecum, with a cut-off value of 2.0 mm. All cats (20/20) showed some degree of macroscopic 'dimpling' of the caecal mucosa on endoscopy. Lymphoid follicles in the caecal mucosa and submucosa constitute a unique follicular layer on ultrasound. In asymptomatic cats, a subtle non-clinically relevant inflammation may exist and this is correlated with an increased thickness of the follicular layer on ultrasound. On endoscopy, a dimpled aspect to the caecal mucosa is a normal finding in the asymptomatic cat. © The Author(s) 2015.

Abdominal ultrasound features and reference values in 21 healthy rabbits

Article

Full-text available

Oct 2014

This study aimed to determine the ultrasonographic features and reference values of the abdominal anatomy in mixed-breed dwarf rabbits. Complete abdominal ultrasonographic examination was performed in 21 mixed-breed rabbits (12 males and 9 females) referred for examination to the Department of Animal Medicine, Production and Health, University of Padua, Italy. All animals were sedated during the procedure. The ultrasonographic anatomy of the abdomen was determined, including measurement (mean±SD) of the right kidney (length 2.87±0.34 mm; width 1.62±0.17 mm; height 1.66±0.14 mm) and left kidney (length 2.86±0.33 mm; width 1.72±0.19; height 1.58±0.15 mm), left adrenal gland (width 0.38±0.11 mm; length 0.71±0.14), right adrenal gland (width 0.34±0.08 mm; length 0.73±0.15 mm) and thickness of the walls of the stomach (0.10±0.01 mm), pylorus (0.28±0.04 mm), duodenum (0.19±0.04 mm), sacculus rotundus (0.22±0.06 mm), caecum (0.08±0.01 mm), appendix (0.19±0.04 mm), spiral loop of the ascending colon (0.14±0.04 mm) and distal colon (0.10±0.02 mm). A significant positive correlation between bodyweight and kidney size, adrenal gland length, stomach wall and sacculus rotundus wall was detected.

Nonoperative management of appendicitis in children

Article

Mar 2017

Purpose of review: The aim of this review is to summarize the recent literature investigating nonoperative management of uncomplicated and complicated appendicitis and highlight recent data establishing its safety and efficacy. Recent findings: Recent studies and clinical trials have demonstrated the efficacy of nonoperative treatment of both uncomplicated and complicated appendicitis, defined as perforated appendicitis with or without formed abscess or phlegmon. Nonoperative management of uncomplicated appendicitis has been reported to be effective in approximately 71-94% of cases. In complicated appendicitis, treatment with antibiotics alone or antibiotics with interval appendectomy has been shown to be a well tolerated and reasonable treatment alternative. Summary: Appendicitis is one of the most common surgical diagnoses in children. The standard of care for many years has been surgical appendectomy; however, it carries with it risks including bleeding, wound complications, injury to surrounding structures, and the potential need for reoperation. Nonoperative management of both uncomplicated and complicated appendicitis in children is well tolerated and efficacious in select populations.

The appendix: a spectrum of benign and malignant disease

Article

Feb 2017

This article discusses the radiological appearances and subsequent management of a diverse spectrum of benign and malignant appendiceal pathologies, including those masquerading as acute appendicitis.

Ultrasonographic, endoscopic and histological appearances of the caecum in cats presenting with chronic clinical signs of caecocolic disease

Article

Sep 2016
J FELINE MED SURG

Objectives: This study aimed to describe the ultrasonographic, endoscopic and histological characteristics of the caecum and ileocaecocolic junction in cats suffering from chronic clinical signs compatible with caecocolic disease. Methods: Cats presenting with clinical signs suggestive of a caecocolic disease were prospectively recruited. All cats underwent an ultrasonographic examination of the caecum, ileum, colon, ileocolic lymph nodes and local mesenteric fat, in addition to comprehensive abdominal ultrasonography. This was followed by a colonoscopy with a macroscopic assessment of the caecocolic mucosa; caecocolic tissue samples were systematically collected for histologic analysis. Results: Eighteen cats were included. Eleven of 18 cats had ultrasonographic abnormalities adjacent to the ileocaecocolic junction (lymphadenopathy, local steatitis) and 13/18 cats had abnormalities directly related to the junction (wall thickening, loss of wall layering). Seventeen of 18 cats had at least one ultrasonographic abnormality. Endoscopically, hyperaemia, oedema, discoloration and/or erosions, were found in all cats. Each cat was classified with mild or moderate-to-severe lesions according to endoscopic results; no classification could be established statistically for ultrasonographic results. The accentuation of the dimpled pattern tended to be inversely related to the severity of endoscopic lesion scoring. Histologically, a large proportion of cats showed typhlitis (13/16), one had lymphoma and two were normal. All cats with typhlitis also had colitis. There was only a slight agreement between endoscopic and histological caecal results on the severity of lesions. Loss of caecal wall layering on ultrasound was found in 7/18 cats and, surprisingly, did not appear as a reliable predictor of the severity of inflammation or of malignancy, and neither did local steatitis nor lymph node size. Conclusions and relevance: Ultrasonography and endoscopy should not be used as the sole methods to investigate the ileocaecocolic region in cats with clinical signs suggestive of caecocolic disease. The presence of chronic clinical signs should routinely prompt histological biopsy.

Comparative anatomy of domestic mammals

Article

Jan 1996
Angiology

R. Barone

A Colour Atlas of the Anatomy of Small Laboratory Animals. Vol. 1, Rabbit. - Guinea Pig

Article

Anatomy of the Rabbit cecum

Article

Jul 1979

Robert L. Snipes

The anatomy of the rabbit cecum was investigated using macroscopic dissections, vascular injections, dried total specimens, light microscopy, and scanning and electron microscopy. The morphology of the three portions of the cecum (ampulla coli, corpus ceci and appendix vermiformis) is described. For comparison, the proximal colon, ileum and sacculus rotundus were also investigated. The thickness of the different layers of the intestinal wall of each area was measured. The arterial supply and mesenteries of the cecum were also studied. The rabbit cecum represents structurally a highly developed organ.

Experimental model of acute appendicitis in the rabbit with determination of leucine amino peptidase (LAP) and acid phosphatase (Acid-P) activities in portal blood samples

Article

Apr 1990

The activities of leucine amino peptidase (LAP) and acid phosphatase (Acid-P), conceivable markers of acute appendicitis, were determined in the portal blood of rabbits with acute appendicitis. An experimental model of acute appendicitis was established using No.-O silk ties to block the base of the appendix. The clinical and histopathological picture of acute appendicitis was seen after 12 hr in all the rabbits in the model group (9/9) and in none of the control group. Catheterization of the superior mesenteric vein was performed in rabbits with acute appendicitis, and portal blood samples were taken at 0, 6, and 12 hr for assay of LAP and Acid-P activities. No statistically significant difference between the experimental group and the control group, in the activities of LAP and Acid-P, was found at any time interval. The experimental model of acute appendicitis in the rabbit which is described here is simple and carries a high rate of success. This is probably the first report of using continuous catheterization and repeated sampling of portal blood, for the measurement of enzyme activities, in an experimental model of acute appendicitis. It was concluded that serum LAP and Acid-P activities cannot be used as markers for acute appendicitis.