Abstract: The present investigation was conducted to explore the prevalence of cholecystic disorders through ultrasonographic evaluation in 130 dogs of different age, sex and breed irrespective of their health status. Sludge, ultrasonographically characterized by echogenic bile or sediments within dependent part of gallbladder without acoustic shadowing was diagnosed in 54 (41.53%) dogs without any sex, breed and age predisposition. Mucocele, ultrasonographically characterized by stellate or striated gravity independent bile pattern and cholecystitis with uniformly thickened reflective gallbladder wall was diagnosed in four (3.07%) and three (2.30%) dogs, respectively.
INTRODUCTION
Cholecystic diseases may be defined as the disorder of the gallbladder and its associated structures. Because of the diagnostic paradox, very few holistic and comprehensive studies are available on cholecystic disorders thus remained as uncommon clinical entities (Holt et al., 2004; Voros et al., 2001; Besso et al., 2000). However, in view of increasing urbanization, environmental pollution, unscientific feeding, stress and abuse of common therapeutic drugs, importance of biliary diseases cannot be ignored. It appears that a detailed and systematic study is really lacking to reflect the magnitude of the problem in India (Tiwari, 2002). Therefore, the present investigation was undertaken to carry out an ultrasonographic survey of cholecystic disorders in dogs.
MATERIALS AND METHODS
The study was conducted in the Referral Veterinary Polyclinic, Indian Veterinary Research Institute, Izatnagar, Bareilly, India for a period of eight months (2002-03). Total one hundred and thirty dogs irrespective of their breed, sex, age and health conditions were included for the study.
Ultrasonographic examination of the liver and gallbladder of these dogs were performed with scanner 200 vet (Pie medical, Netherlands) using a 5.0 MHZ AAS transducer. The animal was prepared by overnight fasting whenever required. Activated charcoal was administered in the morning to reduce gas in gastrointestinal tract. An area from 11th rib to the umbilicus on either side of ventral abdomen was taken after proper shaving, cleaning of the area and placing the animal on dorsal recumbency.
Entire hepatic area was examined by placing the scanner head dorsally or laterally to the caudal area of xiphi-sternum. Both the longitudinal and transverse images of the gallbladder were obtained. Each sonogram was evaluated for hepatic echogenicity, vascularity, gallbladder contents and diseases (like, sludge, mucocele and cholecystitis).
RESULTS AND DISCUSSION
Sludge was identified ultrasonographically as echogenic bile or sediment in the dependent part of gallbladder without acoustic shadowing (Bromel et al., 1998) in 54 dogs (Table 1, 41.53%). Recently Tiwari et al. (2002) also recorded cases of biliary sludge in India. Bromel et al. (1998) reported 53, 62 and 48% incidences of gallbladder sludge in healthy dogs, dogs with hepatobiliary and other diseases, respectively. Though, sludge is considered as precursor of gallstone in human beings, its clinical importance in canine is still not known (Bromel et al., 1998). Mild degree of inflammation or biliary stasis was conjectured to be associated with gallbladder sludge (Voros et al., 2001). However, a close and careful investigation is required owing to its resemblance with tumour (Voros et al., 2001) mucocele (Pike et al., 2004) and cholelithiasis (Jensen et al., 1994; Ward, 2007) with acoustic shadowing.
In the present study, two patterns of sludge were ultrasonographically evident. One was characterized by a clear line of interface between the echogenic sludge and anechoic bile (Fig. 1) as seen in human beings (Bromel et al., 1998). While in other, ill defined accumulation of echogenic materials (Fig. 2) was observed in gallbladder. The gallbladder wall was mostly isoechoic with liver (Bromel et al., 1998) except in three dogs where it appeared hyperechoic. Interestingly in two cases of biliary sludge where there was no obstruction, cystic duct as a continuation of gallbladder neck was discernible unlike earlier findings.
Biliary sludge was not restricted in any specific canine breed (Table
2). The cases were distributed in Pomeranians (27.77%), German Shepherd
(16.66%), Labrador (3.7%), Dobermann (3.7%), Great Dane (5.55%), Bhootia (5.55%),
Dalmatian (7.42%), Boxer (3.7%) and Non-descripts (25.92%). Sex (male 59.35%,
female 40.74%) or age (up to 1 year 35.18%, 1-5 year 46.29%) and over 5 year
(20.37%) did not influence the predisposition of biliary sludge (Table
2) agreeing with the earlier observations of Tiwari (2002) except little
higher incidence in 1-5 year age group. On the contrary, Bromel et al.
(1998) observed a little higher mean age of the dogs with sludge. Of 54 cases
of sludge, 25 were associated with hypoechoic liver (Table 2)
and rest were other wise clinically healthy dogs with no liver involvement.
| Table 1: | Prevalence of cholecystic diseases in dogs |
| Values in parenthesis indicates total population of dogs in the study. Out of 130 dogs 54 were recorded with gallbladder sludge, 4 with mucocele and 3 with cholecystitis | |
| Table 2: | Age, sex and breed wise distribution of cholecystic diseases in dogs |
| Fig. 1: | Ultrasonographic image of canine gallbladder with sludge. There is a clear line of interface between echogenic sludge and anechoic bile |
| Fig. 2: | Ultrasonographic image of canine gallbladder with ill defined accumulation of sludge particles |
Mucocele was ultrasonographically characterized (Reed and Ramirez, 2007) by
immobile gravity dependent stellate (Fig. 3) or finely striated
bile pattern (Fig. 4) and could be diagnosed in four dogs
(3.07%). All the cases were recorded (Table 2) in large sized
(more than 30 kg) aged dogs of both sexes (male-2: female-2). Of these four
cases, three were detected in German shepherd. Due to limited observations,
breed predilection could not be ascertained. However, mucocele was reported
in Cocker Spaniel, Basset, Miniature Schnauzer, Daschund, Poodle, Labrador and
mixed breed in association with biliary stasis and mucosal hyperplasia (Besso
et al., 2000; Pike et al., 2004). The thickness of gallbladder
wall was found to be less than 3.5 mm. No specific clinical sign was observed
in dogs detected with mucocele.
| Fig. 3: |
Transverse ultrasonographic image of canine gallbladder. Distal and central bile form a stellate pattern but the peripheral bile is anechoic. The bile did not move when the position of the patient was changed suggesting that it is gravity independent |
| Fig. 4: |
Ultrasonographic image of canine gallbladder with striated pattern of mucocele |
Cholecystitis was observed in three (male-2: female-1) middle to aged dogs
of small breed (two in Pomeranians and one in Labrador). Ultrasonographically
it was characterized by uniformly thickened (more than 3.5 mm), reflective,
well-delineated (O’Neill et al., 2006) gallbladder wall (Fig.
5). In India sporadic incidences of cholecystitis were recorded (Vijay Kumar
et al., 2001; Tiwari, 2002). Cholecystitis was reported in various diseases
like cystic mucosal hyperplasia, infectious canine hepatitis, pancreatitis,
chronic bile duct obstruction, renal failure and over-hydration in dogs (Jubb
et al., 1993; O’Neill et al., 2006).
| Fig. 5: |
Ultrasonographic image of canine gallbladder with uniformly thick and hyperechoic wall (Thickness 0.55 mm) |
From the above study it may be concluded that ultrasonographic study of the canine gallbladder both in diseased and healthy conditions is a useful weapon to carry out survey of biliary diseases of the dogs. However, an extensive, in-depth and region wise investigation encompassing larger number of patients will be required to get an complete and clear appraisal of status of the canine cholecystic disorders in India.