ArticlePDF Available

Ultrasound morphology of cecal appendix in pet rabbits

Authors:
  • Centro Veterinario Specialistico

Abstract

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.
Vol.:(0123456789)
1 3
Journal of Ultrasound
https://doi.org/10.1007/s40477-018-0316-3
ORIGINAL ARTICLE
Ultrasound morphology ofcecal appendix inpet rabbits
AnnalisaNicoletti1 · NicolaDiGirolamo2· UlrichZeyen1· PaoloSelleri3· MarcoMasi3· PaoloFonti1
Received: 30 April 2018 / Accepted: 27 July 2018
© Società Italiana di Ultrasonologia in Medicina e Biologia (SIUMB) 2018
Abstract
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 morpho-
logical 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.
Keywords Appendix· Rabbit, ultrasound· Appendicitis· Gastrointestinal stasis
Sommario
Scopo L’appendice cecale rappresenta la parte terminale del cieco e tra gli animali domestici è caratteristica del coniglio.
Lo scopo di questo lavoro è di valutare la sua morfologia in ecografia.
Metodi È stato pianificato uno studio prospettico della durata di circa 1 anno. I conigli presentati per ecografia addominale
nel periodo dello studio e senza alterazioni cliniche evidenti dell’apparato gastro-enterico sono stati inclusi. L’ecografia
addominale è stata effettuata tramite contenimento manuale utilizzando una sonda lineare ad elevata frequenza (8-18MHz).
Risultati L’appendice cecale è stata visualizzata in 40/42 (95,2%) animali utilizzando scansioni mediane e paramediane sinis-
tre. La parete appare pluristratificata in accordo con la normale anatomia intestinale ed il contenuto luminale è rappresentato
in tutti i casi da pattern alimentare. La misurazione dell’AWT è stata possibile in tutti i 40 conigli in cui l’appendice è stata
visualizzata mentre la misurazione dell’AD è stata possibile in 39 conigli. Gli intervalli di riferimento per AWT sono stati
di 1,1-2,1mm e per l’AD di 3,9-8,8mm. È stata evidenziata una correlazione negativa tra l’età e AWT (r = -0,35, P = 0,027)
ed una moderata correlazione positiva tra AWT e AD (r = 0,71, P < 0,001).
Conclusioni L’appendice cecale è un organo riconoscibile attraverso l’ecografia nella maggior parte dei conigli. Descriv-
iamo l’aspetto morfologico dell’appendice e forniamo parametri di riferimento per lo spessore parietale e il diametro
dell’appendice, con lo scopo di facilitare la diagnosi delle patologie dell’appendice. La correlazione negativa tra l’età e
* Annalisa Nicoletti
annalisa_nicoletti@virgilio.it
Extended author information available on the last page of the article
Journal of Ultrasound
1 3
AWT indica valori più bassi di AWT associati all’aumento
dell’età, che potrebbe rappresentare la diminuzione della
funzione immunitaria dell’appendice nei conigli adulti.
Introduction
In rabbits, the gastrointestinal tract is composed of a relatively
large stomach that has a well-developed cardiac sphincter that
prevents vomiting and a pyloric area. The small intestine,
divided in duodenum, jejunum and ileum, ends in a rounded
structure unique to the rabbit called sacculus rotundus. The
wall of the sacculus rotundus has abundant aggregations of
lymphoid tissue in the lamina propria and submucosa. The
rabbit cecum is very large and has a capacity roughly ten times
that of the stomach, constituting around 40% of the total gas-
trointestinal tract [1]. The cecum ends with a cecal appendix,
a thick-walled, blind-ended structure whose wall is rich in
lymphoid tissue. The cecal appendix represents a site for the
antibody diversification in young rabbits and has a secretory
function of water and bicarbonate throughout the life of the
animals. The cecum is followed by the colon, which originates
from an area defined ampulla coli and is divided into proximal
and distal colon by the fusus coli [2, 3].
The rabbit has been used as an experimental model to
study acute appendicitis in humans. In these studies, surgical
ligation of the appendix or the obstruction of the appendix
obtained through the placement of a balloon catheter intro-
duced via cecostomy induced ischemic necrosis or inflam-
matory changes of the organ. These modifications were stud-
ied for their similarity with spontaneous human appendicitis
and to evaluate the response to medical or surgical treatment
[46].
Recently, a case of appendicitis and sacculitis in a
9-month-old male rabbit, diagnosed by means of ultrasonog-
raphy and computed tomography, has been reported [7].
Although a previous study reported ultrasonographic
features and size of abdominal organs in healthy rabbits,
including cecal appendix [8], it included a limited number
of cases and no information about the diameter of the organ
and the luminal content was reported.
The purpose of our work is to demonstrate that in nor-
mal condition morphological and structural features of the
appendix are recognizable during basic abdominal ultra-
sonography and to provide reference size for appendix of
gastrointestinal healthy rabbits.
Materials andmethods
A prospective, reference interval, single-center study
was planned for the duration of approximately 1year
(19/12/2016–12/12/2017). All the rabbits that were pre-
sented in the study period for abdominal ultrasound and had
no history and no clinically evident alterations of the gastro-
intestinal tract were eligible for inclusion in the study. Rab-
bits included in the study had no ultrasonographic evidence
of gastrointestinal tract disease. All the rabbits were client-
owned animals. All animals underwent abdominal ultra-
sound examination performed with a GE logiq E9, equipped
with a linear multifrequency hokey stick probe 8–18MHz
with a small parts optimized setting. The animals were
prepared with trichotomy and application of a small quan-
tity of alcohol and ultrasonographic gel. The rabbits were
manually restrained for the duration of the ultrasonographic
examination. A complete abdominal ultrasonographic exam
was performed with the animal in both right and left lateral
recumbency. When possible, the appendix was visualized
in longitudinal and transversal views; wall measures were
taken in longitudinal view because in the authors’ experi-
ence the visibility of the organ and repeatability of measures
were higher. Measures were taken from the interface lumen-
mucosal layer to the serosal one obtaining the wall thickness
and from serosal to serosal layer obtaining the diameter of
the organ (Fig.1).
Statistical analysis
Summary statistics were compiled for measured variables.
Data were analyzed for normality by means of the Sha-
piro–Wilk test. In case appendix wall thickness (AWT)
and appendix diameter (AD) were normally distributed,
ninety percent reference intervals for the variables were
provided. Difference in appendix parameters (AD, AWT)
between male and female rabbits was evaluated by means
of Student t test since the distribution was normal. Corre-
lation between age and appendix parameters and between
Fig. 1 Rabbit, normal appendix, longitudinal view: mucous luminal
pattern. Wall measure from lumen-mucosa interface to sierosal layer
(measure 1). Measure of the appendix diameter (measure 2). The
blind-ended appearance can be noticed (arrows)
Journal of Ultrasound
1 3
AD and AWT was evaluated by calculation of the Pearson
r statistic. Data were analyzed using commercial software
(SPSS statistics v22.0; IBM, Chicago, IL). Two tailed P
values of less than 0.05 were considered significant.
Results
Population summary
A total of 42 pet rabbits were included in the study. The
rabbits were of mixed breed, ranging between 0.5 and 2kg
in weight. Eighteen rabbits were males (9 neutered and
9 intact) and 24 females (17 neutered and 7 intact). The
median age was 54months (2–156).
Visualization andmorphology ofappendix
In two rabbits, it was not possible to identify cecal appen-
dix. In the remaining 40 rabbits, the appendix was visual-
ized and the ultrasonographic examination was allowed to
study wall structure and luminal content. In all cases, the
appendix was visualized through median and/or left para-
median views. The appendix was recognizable as a tubular
structure with a rounded, closed end and a multilayered
wall characteristic of the intestinal tract. In all cases, the
luminal content had an alimentary pattern (Figs.2, 3 and
4), and no appendix had evidence of fluid content. In one
rabbit, the shadow generated from the luminal pattern lim-
ited visualization of the distal wall of the appendix prohib-
iting measurement of AD. Therefore, 40 rabbits had meas-
urement of AWT and 39 rabbits had measurement of AD.
Reference ranges forappendix wall thickness
andappendix diameter
Both AWT and AD were normally distributed (Shap-
iro–Wilk: P = 0.58 and P = 0.91, respectively). On aver-
age, AWT measured 1.5mm (SD: 0.3; range 0.8–2.2).
Male had a mean AWT of 1.53 ± 0.29mm and females of
1.48 ± 0.32mm. The mean difference between male and
female was 0.05mm (95% CI −0.14 to 0.25) and not statis-
tically significant (P = 0.59). Reference intervals for AWT
were 1.1 to 2.1mm. The mean AD was 6.1mm (SD: 1.4;
range: 2.6–9.2). Male had a mean AD of 6.07 ± 1.39mm and
Fig. 2 Rabbit, normal appendix: alimentary luminal pattern. The state
of repletion can be variable and the wall (w) shows an attenuated
echogenicity
Fig. 3 Rabbit, normal appendix in longitudinal (a) and transversal (b)
views: alimentary luminal pattern. The state of repletion can be vari-
able in normal conditions and the wall (w) shows an attenuated echo-
genicity, sierosa is visible as a hyper-echoic linear structure (arrows)
Fig. 4 Rabbit, normal appendix in longitudinal view. In this case,
the appendix shows a higher state of repletion compared to previous
images and the luminal content creates a posterior acoustic shadow
(arrows)
Journal of Ultrasound
1 3
females of 0.07 ± 1.53mm. The mean difference between
male and female was −0.004mm (95% CI −0.96–0.95)
and not statistically significant (P = 0.99). Reference inter-
vals for AD size were 3.9–8.8mm. There was no corre-
lation between age and AD (r = 0.01, P = 0.94) but there
was a weak negative correlation between age and AWT
(r = −0.35, P = 0.027), indicating lower values of AWT
associated with increasing age, and a moderate positive cor-
relation between AWT and AD (r = 0.71, 95% CI 0.53–0.83;
P < 0.001) (Table1).
Discussion
Gastrointestinal stasis is a common condition in rabbits; it is
not related exclusively to pathologies of the gastrointestinal
tract but could be the expression of several problems. As
in other animals as dogs and cats, abdominal ultrasonog-
raphy is an important evaluation in the clinical practice; it
provides useful clinical and operative information in a non-
invasive way. It consents to differentiate mechanical stasis to
functional ones, allowing to detect foreign bodies or indirect
signs of mechanical ileus, as segmental fluid or gas accumu-
lation within the stomach or part of the intestinal tract, and to
individuate signs of inflammatory bowel disease [3, 9, 10].
In our opinion, the evaluation of the appendix has always to
be included in abdominal ultrasound, because pathologies
of the organ are reported [7, 11]. In human medicine, the
visualization of normal appendix on sonography is reported
to appear advantageous in reducing the percentage of false-
negative cases of appendicitis. Moreover, ultrasonography
is considered a readily available, inexpensive, non-invasive
test with a reported sensitivity of 80–94% in the detection
of acute appendicitis [12] and it is the preferred imaging
modality in pregnant woman and in children suspected of
acute appendicitis, because radiation exposure is an impor-
tant concern in managing this kind of patients [13, 14]. Con-
sidering published works in human and veterinary medicine
and the authors’ experience, abdominal ultrasound probably
can help to detect morphological changes that involve the
wall structure and the luminal pattern in course of appendix
diseases. This work wants to focus on the ultrasonographic
features of the appendix in condition of normality; further
studies are necessary to establish the ultrasonographic
changes of the appendix in course of appendicitis. In the
present study, we found a negative correlation between
age and AWT. In young rabbits, the appendix represents
an important site for development of the primary antibody
repertoire. Although the rabbit appendix does not involute,
it changes in appearance, possibly in function, and partially
atrophies with age [15]. We suggest that probably lower val-
ues of AWT associated with increasing age could be related
to the physiological decrease in the immunitary function of
the appendix in aged rabbits.
Conclusions
Based on our study, cecal appendix is recognizable via
ultrasound through median and/or left paramedian views
in the vast majority of rabbits. We describe the normal
morphological aspect of the appendix and we provide ref-
erence intervals for wall thickness and diameter, in order
to aid in the diagnosis of disorders of the appendix. We
found a weak negative correlation between age and AWT
that suggests that lower values of AWT are associated with
increasing age, hypothesis that has to be confirmed with
further studies. We also found a moderate positive cor-
relation between AD and AWT. We suspected that AD is
positively related with the repletion state of the organ and
that can be variable in the same individual. However, fur-
ther research with multiple monitoring of the same rabbits
at different times is required to prove this hypothesis. We
also describe the normal luminal content of the appendix
that in all cases was represented by the alimentary pattern.
Compliance with ethical standards
Conflict of interest The authors declare that they have no conflict of
interest.
Ethical approval All procedures performed in studies involving animals
were in accordance with the ethical standards of the institution or prac-
tice at which the studies were conducted. This article does not contain
any studies with human participants performed by any of the authors.
Human and animal rights statement All the described animal-related
procedures were conducted according to the Directive 2010/63/EU
of the European Parliament and of the Council of September 22nd
2010 on the protection of animals used for scientific purposes (Art.1,
Par.1, letter “b”), which does not require any approval by the competent
Authorities.
Informed consent Informed consent was obtained from all individual
participants included in the study.
Table 1 Summary of measurements of appendix wall thickness
(AWT) and appendix diameter (AD) obtained in 40 and 39 rabbits,
respectively
Both variables were normally distributed (Shapiro–Wilk > 0.05)
AWT (mm) AD (mm)
Mean 1.51 6.07
Standard Deviation .30 1.45
Minimum .80 2.60
Maximum 2.20 9.20
Journal of Ultrasound
1 3
References
1. Jenkins J (1999) The veterinary clinics of North America. Exotic
animal practice. WB Saunders, Philadelphia
2. Quesenberry KE, Carpenter JW (2012) Ferrets, rabbits and
rodents. Clinical medicine and surgery, 3rd edn. Elsevier/Saun-
ders, section2
3. Selleri P, Di Girolamo T, Collarile T (2017) Medicina e chirur-
gia degli animali esotici, vol 415. Poletto Editore, MI Italia, pp
386–387
4. Nunes FC, Silva AL (2005) Acute ischemic appendicitis in rab-
bits: new model with histopathological study. Acta Cir Bras
20(5):399–404
5. Pieper R, Kager L, Tidefeldt U (1982) Obstruction of appendix
vermiformis causing acute appendicitis. An experimental study
in the rabbit. Acta Chir Scand 148(1):63–72
6. Simsek G, Servinc B, Onlu Y, Hasirci I, Kurku H, Karahan O
(2016) Effect of medical treatment on histological findings in
rabbits with acute appendicitis. Ulus Travma Acil Cerrahi Derg.
22(6):516–520
7. Longo M, Thierry F, Eatwell K, Schwarz T, Pozo JD, Richardson
J (2018) Ultrasound and computed tomography of sacculitis and
appendicitis in a rabbit. Vet Radiol Ultrasound 1–5. https ://doi.
org/10.1111/vru.12602
8. Banzato T, Bellini L, Contiero B, Selleri P, Zotti A (2015)
Abdominal ultrasound features and reference values in 21 health
rabbits. Vet Rec 176:101
9. Penninck D, D’anjou MA (2008) Atlas of small animal ultra-
sonography, 1st edn. Wiley-Blackwell, Ames IA, p 287
10. Baez JL, Hendrick MJ, Walker LM, Washabau RJ (1999) Radio-
graphic, ultrasonographic and endoscopic findings in cats with
inflammatory bowel desease of the stomach and small intestine:
33 cases (1990–1997). J Am Vet Med Assoc 215(3):349–354
11. Fujiwara H, Uchida K, Takahashi M (1987) Occurrence of granu-
lomatous appendicitis in rabbits. Jikken Dobutsu. 36:277–280
12. Rioux M (1992) Sonographic detection of the normal and abnor-
mal appendix. AJR 158:773–778
13. Kazemini A, Reza Keramati M, Fazeli MS, Keshvari A, Khaki S,
Rahnemai-Azar A (2017) Accuracy of ultrasonography in diag-
nosing acute appendicitis during pregnancy based on surgical
findings. Med J Islam Repub Iran. 31:48
14. Sola R Jr, Theut SB, Sinclair KA, Rivard DC, Johnson KM,
Zhu H, St Peter SD, Shah SR (2018) Standardized reporting of
appendicitis-related findings improves reliability of ultrasound in
diagnosing appendicitis in children. J Pediatr Surg. 53(5):984–987
15. Dusso JF, Obiakor H, Bach H, Anderson AO, Mage RG (2000) A
morphological and immunohistological study of the human and
rabbit appendix for comparison with the avian bursa. Dev Comp
Immunol 24:797–814
Aliations
AnnalisaNicoletti1 · NicolaDiGirolamo2· UlrichZeyen1· PaoloSelleri3· MarcoMasi3· PaoloFonti1
1 Diagnostica perimmagini, Centro Veterinario Specialistico,
via S. Giovannini 51-53, 00137Rome, Italy
2 Tai Wai Small Animal andExotic Hospital, 69-75 Chik Shun
street, Tai Wai, Shatin, ShaTin, HongKong
3 Clinica peranimali Esotici, Centro Veterinario Specialistico,
via S. Giovannini 51-53, 00137Rome, Italy
... It has been observed that appendix size decreases with age both in laboratory rabbits 32 and in client-owned rabbits. 23 Therefore, it is possible that acute appendicitis affects rabbits that are undergoing involution of the organ. In humans, appendicitis affects all age groups, although the incidence is increased between the ages of 10 and 20 years. ...
... Recently, our research group investigated the ultrasonographic morphology of the appendix in 42 clinically normal rabbits and determined overall appendix diameter and appendix wall thickness for 40 and 39 rabbits, respectively. 23 The appendix was observed in median or left paramedian views in 95.2% (40/42) of the rabbits. 23 The appendix appeared as a tubular structure with a multilayered wall, a luminal content with alimentary pattern, and a rounded, closed end. ...
... 23 The appendix was observed in median or left paramedian views in 95.2% (40/42) of the rabbits. 23 The appendix appeared as a tubular structure with a multilayered wall, a luminal content with alimentary pattern, and a rounded, closed end. In healthy rabbits, the appendix had no evidence of fluid content; in only 1 of 40 healthy rabbits, the luminal pattern generated a posterior acoustic shadow that limited visualization of the distal wall of the appendix. ...
Article
Full-text available
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.
... The normal appendix wall thickness measured by ultrasound is 1.1-2.1 mm, and the normal appendix diameter is 3.9-8.8 mm (5). The wall shows an attenuated echogenicity, and the serosa is visible as a hyperechoic linear structure (5). ...
... mm (5). The wall shows an attenuated echogenicity, and the serosa is visible as a hyperechoic linear structure (5). The contents can be a variable amount in normal conditions. ...
... Nicolletti et al. (5) described a negative correlation between age and appendix wall thickness, suggesting that lower values of thickness are associated with increasing age, caused by a physiological decrease in the immune function of the appendix in adult rabbits. In presented cases, appendix wall thicknesses were 4.2 and 3.7 mm, respectively. ...
Article
Full-text available
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.
... Arthur and Gates (1988) reported a soil intake of a magnitude of more than 6% of dry matter in free-ranging black-tailed jackrabbits (Lepus californicus), and Rödel (2005) described the presence of sand in the faeces of European rabbits. The lagomorph GIT anatomy is characterised by an elongated caecum that ends in a voluminous appendix (Snipes, 1979), which is situated on the left side of the abdomen (Nicoletti et al., 2018;Rees Davies & Rees Davies, 2003). The lagomorph GIT thus comprises a distinct dead-end structure that might be particularly prone to the accumulation of soil. ...
... These depictions obliterate the observation that the appendix crosses the abdominal cavity from the right to the left side, so that its tip can typically be detected via ultrasound in the left abdomen (Nicoletti et al., 2018). We provide an interpretative graphic depiction of the (a) A r (b) B r (c) C r (d) C gp ...
... As a side note, in one of 40 domestic rabbits in which Nicoletti et al. (2018) visualised the appendix tip via ultrasound, the content of the appendix created an acoustic shadow that prevented the view of the appendix' distal wall; possibly, this was radiodense sand. To which extent such appendix sand occurs in rabbits kept as pets, and in freeranging animals, remains to be investigated. ...
Article
Full-text available
We determined location and amount of accumulated sand in the gastrointestinal tract (GIT) of rabbits (Oryctolagus cuniculus) and guinea pigs (Cavia porcellus) fed diets containing external (silicate) abrasives. Computed tomographic abdominal images of rabbits (n=44) and guinea pigs (n=16) that each received varying numbers (4-7) of different diets for 14 days each (total n=311 CTs), and radiographs of dissected GIT and presence of silica in GIT content (n=46 animals) were evaluated. In rabbits, the majority of accumulated sand was located in the caecal appendix, an elongated, intestinal structure in the left side of the abdomen. The ‘wash-back’ colonic separation mechanism in rabbits may be partly responsible for a retrograde transport of sand back to the caecum, where dense, small particles accumulate in the appendix. The appendix likely acted as a reservoir of these particles, leading to significant effects not only of the momentary but also of the previous diet on recorded sand volumes in the rabbits. Guinea pigs have no caecal appendix and a colonic separation mechanism not based on a ‘wash-back’. Less sand accumulation was found in their GIT without a specific location pattern, and there were less previous diet effects in this species. None of the rabbits or guinea pigs developed clinical signs of obstruction during the study, and the recorded sand volumes represented 1.0 ±1.2% of the 14-d sand intake in rabbits and 0.2 ±0.2% in guinea pigs. Accumulation of sand in volumes up to 10 cm³ in the gastrointestinal tract of rabbits does not seem to cause clinical health impairment. Large inter-individual differences in rabbits indicate inter-individual variation in proneness to sand accumulation. The reason for the presence of a sand-trapping caecal appendix in animals that are, due to their burrowing lifestyle and feeding close to the ground, predestined for accidental sand ingestion, remain to be unveiled.
... Diagnostic imaging is an essential diagnostic tool for veterinarians working with exotic companion mammals [11,12,27,32]. Ultrasonographic evaluation of the GI tract in rabbits is challenging due to reverberation artifact caused by the normal large amount of gas and ingesta, mainly in the cecal region [11,[26][27][28][29][30]. Radiographic examination can be useful in the diagnosis of some GI diseases, but its use is limited when GI syndrome is suspected [1,7,8,14,32]. ...
... If the GI tract was more distended by gas and/or ingesta, there was more compression and displacement of the sacculus rotundus and appendix, making their identification difficult. Other researchers have previously reported reference values for appendix wall thickness in rabbits [23,29]. Identification of structures was easiest in animals with emptier intestines and more abdominal fat. ...
Article
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.
... Diagnostic imaging is an essential diagnostic tool for veterinarians working with exotic companion mammals [11,12,27,32]. Ultrasonographic evaluation of the GI tract in rabbits is challenging due to reverberation artifact caused by the normal large amount of gas and ingesta, mainly in the cecal region [11,[26][27][28][29][30]. Radiographic examination can be useful in the diagnosis of some GI diseases, but its use is limited when GI syndrome is suspected [1,7,8,14,32]. ...
... If the GI tract was more distended by gas and/or ingesta, there was more compression and displacement of the sacculus rotundus and appendix, making their identification difficult. Other researchers have previously reported reference values for appendix wall thickness in rabbits [23,29]. Identification of structures was easiest in animals with emptier intestines and more abdominal fat. ...
Article
Background There are few studies describing characteristics of the urinary tract in rabbits using multidetector computed tomography (CT). The aim of this study was to describe the CT appearance and main features of the urinary tract in healthy pet rabbits. Methods Twenty-three healthy rabbits underwent plain and contrast-enhanced CT scan under general anesthesia. Results Normal renal length was 3.27-3.43 cm. The ureters were identified in the pre-contrast phase, but better delineated in post-contrast phases. Some focal filling defects were observed in the middle and caudal third of the ureters in more than 50% of the animals on post-contrast exams. There was interobserver disagreement regarding the measurements of renal pelvis, ureters, and the exact position of the kidneys in relation to the lumbar vertebrae. Conclusions and clinical relevance This study provides a detailed anatomic description of the urinary tract in rabbits from CT imaging and reference values for further investigations.
... In fact, rabbits have a voluminous cecumcolon, detectable by ultrasonography, at the level of the right hemiabdomen, in contact with the abdominal wall. On a cadaveric model, the presence of fermentations and meteorism creates artifacts that make the ultrasound visualization of the three muscle planes more complex [23,24]. We hypothesize, therefore, that visualization of the abdominal wall on live rabbits should be better. ...
Article
Full-text available
The aim of this study was to describe one-point (preiliac approach) and two-point (preiliac and retrocostal approach) blocks of the Transversus Abdominis Plane (TAP) on a cadaveric model. For this purpose, ultrasound-guided infiltration of the plane between the internal oblique and transversus abdominis muscles was performed and, after dissection of tissues, the areas and percentage of nerve fibers involved were analyzed. Injection into the TAP plexus of a 1 mL/kg solution of 2% lidocaine and 1% methylene blue (1:1) was performed in 30 rabbit cadavers. In fifteen rabbits (group S), the solution was inoculated at the preiliac level. In the other 15 rabbits (group D), the solution was divided into two inoculations (0.5 mL/kg at the retrocostal level and 0.5 mL/kg at the preiliac level). All cadavers were then dissected and stained spinal nerve branches were measured. Moreover, the percentage of length, height and the total area of the stained tissue were calculated. In the S group, T10, T11 and T12 nerve eminences were successfully stained in 18%, 52% and 75% of cases, respectively. Furthermore, L1, L2, L3 and L4 were stained in 95%, 100%, 60% and 40% of cases, respectively. In group D, the ventromedial eminence of T10, T11 and T12 were stained in 68.1%, 100% and 98% of cases, respectively, and L1, L2, L3 and L4 were stained in 88%, 100%, 62% and 31% of cases, respectively. In conclusion, a two-point TAP block is more effective in covering the nerve eminences of the cranial abdomen than the preiliac approach alone.
Article
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.
Article
Objectives: Thermal stress negatively affects the productive performance and immunity responses of rabbits. In this study, we examined the effects of two allicin (AL) and lycopene (LP) levels on performance index, a liver tumor necrosis factor (TNF-α) gene expression, histological parameters of liver, and small intestine of V-line growing rabbits exposed to thermal stress. Methods: In nine replications of three rabbits per pen under thermal stress, 135 male rabbits (5 weeks old, average weight 772.02 ± 6.41 g) were randomly allocated to five dietary treatments in nine replications of three rabbits per pen under thermal stress (temperature-humidity index average 31.2). The 1st group served as the control, receiving no supplements; The 2nd and 3rd groups received 100 and 200 mg AL/kg of diet supplements; and the 4th and 5th groups were supplemented with 100 and 200 mg LP/kg diet, respectively. Results: show that AL and LP rabbits had the best final body weight, body gain, and feed conversion ratio compared with the control. compared with control, rabbit liver TNF- α levels significantly decreased in diets containing AL and LP In contrast, AL rabbits were slightly more effective in downregulating the expression of the TNF-α gene than LP groups. Furthermore, dietary supplementation of AL and LP significantly improved antibody titers against sheep red blood titers. Compared with other treatments, AL100 treatment significantly improved immune responses to phytohemagglutinin. In all treatments, histological analysis revealed a significant reduction in binuclear hepatocytes. The diameter of the hepatic lobules, villi height, crypt depth, and absorption surface of heat-stressed rabbits were all positively affected by both doses of LP (100-200 mg/kg diet). Conclusion: rabbit dietary supplementation with AL or LP could positively affect performance, TNF-α, immunity, and histological parameters of growing rabbits under thermal stress.
Article
Full-text available
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.
Article
Full-text available
Background: Acute appendicitis is the most common nonobstetric surgical problem in pregnancy. Common signs and symptoms of appendicitis are less reliable during pregnancy due to physiological changes; thus, the role of imaging becomes prominent. Thus, in the present study, we aimed at assessing the accuracy of sonography in diagnosing acute appendicitis during pregnancy. Methods: In this prospective analytic study, among 1000 patients diagnosed and treated as acute appendicitis, clinical and sonographic findings of 58 consecutive pregnant patients, who underwent appendectomy, were recorded and analyzed. All surgically resected samples were evaluated and confirmed through histological evaluation. Sonographic criteria were utilized to judge the results for appendicitis. Diagnostic test performance characteristics (sensitivity, specificity, predictive values, and likelihood ratios) were calculated. Results: The mean age of the patients was 27.1±4.9 years, and the most common clinical symptom was right lower quadrant pain. There was no significant difference in the mean leukocyte count between the appendicitis group and normal appendix group (p=0.768). Left shift was also unrelated with the appendix pathology (p= 0.549). The sensitivity, specificity, predictive values (positive and negative), and likelihood ratios (positive and negative) were 80%, 75%, 91.4%, 52.9%, 3.2, and 0.26, respectively during all trimesters of pregnancy. Conclusion: Ultrasonography is the initially preferred imaging modality in pregnant women suspected of having acute appendicitis with an acceptable sensitivity; however, application of other imaging modalities such as CT scan or MRI is recommended after inconclusive ultrasonography results.
Article
Full-text available
Background: Acute appendicitis (AA) is the most common reason for abdominal surgery in the world. The aim of this study was to evaluate the effect of medical treatment on histological findings in rabbits with AA. Methods: Twenty-one male New Zealand rabbits were divided into 3 groups: appendix ligation and medical treatment, appendix ligation and no treatment, and control group, which underwent only laparotomy. Results: In appendix ligation without treatment group, AA findings were much more severe. Conclusion: Medical treatment reduced inflammation of AA.
Article
Full-text available
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.
Article
Purpose Our objective was to increase ultrasound reliability for diagnosing appendicitis in an academic children's hospital emergency department (ED) through a multidisciplinary quality improvement initiative. Methods A retrospective review of ultrasound use in patients diagnosed with appendicitis in our ED from 1/1/2011–6/30/2014 established a baseline cohort. From 8/1/2014–7/31/2015 a diagnostic algorithm that prioritized ultrasound over CT was used in our ED, and a standardized template was implemented for the reporting of appendicitis-related ultrasound findings by our radiologists. Results Of 627 patients diagnosed with appendicitis in the ED during the retrospective review, 46.1% (n = 289) had an ultrasound. After implementation of the diagnostic algorithm and standardized ultrasound report, 88.4% (n = 236) of 267 patients diagnosed with appendicitis had an ultrasound (p < 0.01). The frequency of indeterminate results decreased from 44.3% to 13.1%, and positive results increased from 46.4% to 66.1% in patients with appendicitis (p < 0.01). The sensitivity of ultrasound (indeterminate counted as negative) increased from 50.6% to 69.2% (p < 0.01). Conclusions Ultrasound reliability for the diagnosis of appendicitis in children can be improved through standardized results reporting. However, these changes should be made as part of a multidisciplinary quality improvement initiative to account for the initial learning curve necessary to increase experience. Level of Evidence. Level II, Study of Diagnostic Test.
Article
A concise guide to the care of small mammals, Ferrets, Rabbits, and Rodents: Clinical Medicine and Surgery covers the conditions seen most often in veterinary practice. The book emphasizes preventive medicine along with topics including disease management, ophthalmology, dentistry, and zoonosis. More than 400 illustrations demonstrate key concepts related to radiographic interpretation, relevant anatomy, and diagnostic, surgical, and therapeutic techniques. Now in full color, this edition adds coverage of more surgical procedures and expands coverage of zoonotic disease. From editors Katherine Quesenberry and James W. Carpenter, along with a team of expert contributors, the "Pink Book" provides an authoritative, single source of information that is hard to find elsewhere.
Article
A prospective study of 170 patients with suspected appendicitis was performed to assess the value of sonography in detecting the normal and abnormal appendix. The wall thickness (normal, less than or equal to 3 mm), compressibility of the appendix, and echogenicity of surrounding fat were the primary criteria used to determine the status of the appendix. Of 60 patients who underwent surgery, appendicitis was proved in 45. The remaining 110 patients who did not have surgery, contacted by telephone at the end of the study, had no clinical follow-up evidence of acute appendicitis. A normal appendix was clearly identified in 102 (82%) of 125 patients without acute appendicitis. The sensitivity of sonographic examination in detecting appendicitis was 93%, the specificity was 94%, and the accuracy was 94%. The predictive value of a positive test was 86%; that of a negative test was 98%. Ruptured appendicitis was predicted in all cases (11/11). Sonography is useful in detecting acute appendicitis and can clearly show the normal appendix more frequently than previously reported.
Article
Granulomatous appendicitis was observed in all of the 45 Japanese white rabbits examined. Histologically, multiple microgranulomas were accompanied with foreign body giant cells and focal calcifications in lymph nodules of appendix. Foreign body giant cells contained hair coat and larvae of Passalurus ambiguus. In addition, the sacculus rotundus and mesenteric lymph nodes were affected with the same lesions. PAS- and Gram- positive bacilli were phagocytized in the microgranulomas and macrophages. They were also stained positively with the immunoperoxidase method for the auto-sera of rabbits. Isolation of these bacilli in pure culture has not yet been accomplished. The occurrence of granulomatous lesions due to tuberculosis, pseudotuberculosis, tularemia and actinomycosis seems unlikely in the present cases because none of these organisms nor characteristic lesions were detected. It was suggested that the Gram-positive bacilli appeared to play a role in granulomatous appendicitis.
Article
In an experimental model using the rabbit, the role of obstruction in the pathogenesis of acute appendicitis was studied. Twenty-one animals were anaesthesized and underwent laparotomy. The appendices were obstructed by a balloon catheter introduced via a caecostomy. Pressures inside the obstructed appendices were measured by a balloon at the tip of the catheter. The abdominal cavity was closed, anaesthesia was continued, and pressure were registered regularly up to 12 hours afterwards in those animals which remained alive during this period. The animals were then sacrificed, and at autopsy evidence of obstruction, distention and inflammatory changes, both gross and microscopic, was registered. In a total of 15 rabbits, experimental obstruction of the appendix resulted in inflammatory changes in the wall of the appendix, which histologically in all respects were similar to appendicitis in man. In the remaining 6 rabbits, either spontaneous release of obstruction or death early during the experiment occurred. Our experimental data suggest that obstruction is an important agent in the causation of acute appendicitis.
Article
To characterize imaging findings in cats with confirmed inflammatory bowel disease (IBD) of the upper gastrointestinal tract (i.e., stomach and small intestine) and relate these findings to clinical signs and histologic changes. Retrospective study. 32 cats with clinical and histopathologic diagnoses of IBD. Medical records were reviewed for signalment, clinical signs, clinicopathologic findings, radiographic and ultrasonographic findings, and results of endoscopic examination. Histologic findings were reviewed and characterized by severity and type of inflammatory infiltrate. All cats had 1 or more clinical signs (e.g., vomiting, diarrhea, weight loss, and anorexia) consistent with IBD. Lymphocytic and plasmacytic infiltrates were observed in histologic sections of gastrointestinal tissue. Crypt distortion, villous blunting and fusion, and fibrosis were most commonly seen in cats with moderate or severe IBD. Clinicopathologic findings of some cats included anemia, leukocytosis or leukopenia, hypocholesterolemia, and hyper- or hypoproteinemia. Abnormalities were not found on abdominal radiographic views in 9 of 9 cats. However, contrast studies using barium revealed radiographic abnormalities in 1 of 3 cats. In 13 of 17 cats, abdominal ultrasonography revealed several intestinal abnormalities (e.g., poor intestinal wall layer definition, focal thickening) and large mesenteric lymph nodes with hypoechoic changes consistent with IBD. Endoscopic observation revealed findings (e.g., erythema, plaques, mucosal friability) consistent with inflammation in 9 of 18 cats. Compared with endoscopy of the gastrointestinal tract or abdominal radiography, clinical signs and ultrasonographic findings appear to have the best association with histologic grade of IBD in cats.