Radiographic diagnosis of liver disease in dogs and cats

Body Weight as a Preferred Method for Normalizing the Computed Tomography-Derived Liver Volume in Dogs without Hepatic Disease

The assessment of liver size is usually performed using radiography in dogs. However, due to wide variations in patients' sizes and body conformations, accurate diagnosis of hepatomegaly or microhepatia is difficult. Computed tomographic (CT) volumetry can quantitatively and accurately measure liver volume. However, a reliable method for the standardization or normalization of volume in dogs without hepatic disease using CT has not yet been established. The purpose of this study was to assess seven different anatomic measures for normalizing liver volume in dogs and determine the tentative range of liver volume in dogs without hepatic disease. We retrospectively searched medical records from 1 January 2017 through to 1 June 2020 and included dogs with abdominal computed tomography without hepatic disease. The liver volume, lengths of four vertebrae (T11, T12, L2, L3), diameter of the abdominal aorta, body weight, and body condition scores (BCSs) of the dogs were recorded. Forty-one client-owned dogs without evidence of hepatic disease were included. The CT-derived liver volume was 813.8 ± 326.5 cm3 (mean ± SD). Body weight was determined to be the most reliable single-variable method for normalizing liver volume, with a raw CT-derived liver-volume-to-body-weight ratio of 22.1 cm3/kg (95% CI: 12.9-31.3 cm3/kg) and regression prediction model of volume = 19 × BWkg + 97. However, a better normalizing factor would likely be provided by the fat-free mass if it can be accurately measured.

Retrospective quantitative assessment of liver size by measurement of radiographic liver area in small-breed dogs

OBJECTIVE

To determine the feasibility of radiographic measurement of liver area in small-breed dogs and to assess correlations between CT liver volume measurements (reference standard) and radiographic liver size measurements.

ANIMALS

107 small-breed dogs (body weight, ≤ 10 kg) that had previously undergone orthogonal thoracic and abdominal radiography and abdominal CT.

PROCEDURES

In a retrospective study design, dogs were allocated to groups (normal liver [n = 36], microhepatia [34], and hepatomegaly [37]) on the basis of radiographic liver size and clinicopathologic findings. Radiographic liver area (RLA) was automatically calculated from archived radiographic images by free-hand outlining of the liver margins by use of DICOM viewer software, and other standard radiographic measurements were performed. Liver volume was measured on CT images. Intraoperator repeatability of RLA and CT measurements was assessed (duplicate measurements 2 weeks apart). To control for various breed conformations, radiographic values were normalized to body weight and T11 area.

RESULTS

Mean ± SD ratios of RLA to T11 area and RLA to body weight for dogs with normal livers were 32.7 ± 6.2 and 7.0 ± 1.4, respectively. Excellent intraobserver agreement was observed in RLA measurements within groups (intraclass correlation coefficients, 0.861 to 0.989), and RLA measurements had the highest correlation with CT liver volume measurements (r = 0.94) of all radiographic measurements.

CONCLUSIONS AND CLINICAL RELEVANCE

Findings indicated that RLA measurement in small-breed dogs with or without liver disease was useful and accurate for estimation of liver size, compared with CT measurement, and might be particularly useful for monitoring of changes in liver size.

Diagnostic imaging of canine hepatobiliary affections: a review

Hepatic disease is often treatable and has a predictable prognosis when a definitive diagnosis is made. The aim of clinicopathological evaluation of hepatobiliary affections is to identify and characterize hepatic damage and dysfunction, identify possible primary causes of secondary liver disease, differentiate causes of icterus, evaluate potential anaesthetic risks, assess prognosis and response to xenobiotics, and monitor response to therapy. This paper describes the different diagnostic methods and imaging techniques employed in diagnosis of hepatobiliary affections in dogs. Besides reviewing the significant clinical manifestations and imaging structural abnormalities in diagnostic approach to different hepatic affections, it also depicts radiographic, ultrasonographic, and wherever applicable, the laparoscopic characterization of different hepatic affections and target lesions encountered in clinical cases presented in the Teaching Veterinary Clinical Complex, COVAS, Palampur in the year 2007-2008.

Ultrasound-guided percutaneous portocentesis in 21 cows

An ultrasound-guided portocentesis was performed in 21 clinically healthy cows, and blood was collected for haematological, biochemical and blood-gas analyses. At the same time blood samples were collected from the left jugular vein of each cow for the same analyses. Immediately after the centesis, portal blood pressure was measured. The cows were examined daily thereafter for eight days and then slaughtered for postmortem examination of the internal organs. The mean (sd) portal blood pressure was 37.1 (5.47) mmHg, and ranged from 24 to 49 mmHg. There were small but significant differences between many of the haematological and biochemical parameters in jugular and portal blood, and the concentration of bile acids was on average 2.7 times higher, and the concentration of ammonia was 19.3 times higher in portal blood. The demeanour and behaviour of the cows, and their appetite and rectal temperature remained normal during the eight-day observation period. The haematocrit, total and differential leucocyte counts, and the concentrations of total solids and fibrinogen were not affected by portocentesis. On postmortem examination, no lesions were apparent in the peritoneum, liver and portal vein.

Transvenous coil embolization of an intrahepatic portosystemic shunt in a dog

To treat an intrahepatic portosystemic shunt in a young dog, thrombogenic material was placed into the vessel lumen (transvenous coil embolization) under fluoroscopic control. One coil was placed into the shunt, followed one month later by two additional coils. Transvenous embolization may become a useful method in the treatment of some portosystemic shunts.

Gallbladder perforation associated with cholelithiasis and cholecystitis in a dog

A four-year-old female Japanese akita was admitted with icterus, ascites and chronically elevated serum bilirubin and liver enzymes. Abdominal ultrasonography revealed a diffusely thickened, hyperechoic gallbladder wall with a focal defect, hepatic lymphadenopathy and a large volume of anechoic fluid within the peritoneal space. Diagnosis of biliary tract rupture with bile peritonitis was based on the findings of bile and suppurative exudate in peritoneal aspirates. A perforated gallbladder and cholelithiasis were found on exploratory celiotomy, while histopathology revealed chronic suppurative cholecystitis. The dog recovered uneventfully after cholecystectomy. Although rare, the triad of cholelithiasis, cholecystitis and gallbladder perforation should be considered after detection of one of these conditions.

Radiographic abnormalities in canine multicentric lymphoma: a review of 84 cases

The thoracic and abdominal radiographs of 84 dogs with multicentric lymphoma were examined to identify the radiological abnormalities. The frequency of occurrence of individual changes, role of radiography in diagnosis, relationship of radiographic changes to hypercalcaemia and prognostic relevance of radiographic findings were assessed. Multiple abnormalities were more commonly seen than solitary changes. No radiographic abnormalities were seen in approximately one quarter of thoracic radiographs and one fifth of abdominal radiographs. Lymphoma could not be diagnosed on the basis of radiographs alone. Many of the features of lymphoma were non-specific, having numerous possible causes. Cranial mediastinal disease was neither a prerequisite for, nor a disproportionately common finding in, hypercalcaemic patients. The absence of radiological abnormalities may be a positive prognostic indicator for the individual patient. The differential diagnoses for the radiographic abnormalities seen in lymphoma are discussed.

Hepatic imaging with radiology and ultrasound

Radiographically, the diseased liver may change in size, shape, position, or opacity. Contrast studies such as peritoneography, cholecystography, portography, and arteriography may be performed to increase the specificity of the radiographic diagnosis. Ultrasound can be used to detect the changes in liver echogenicity associated with disease, identify focal verses diffuse disease processes, detect vascular and biliary abnormalities noninvasively, and direct needle aspirates and biopsies for culture, cytology, and histopathology.

Radiographic and ultrasonographic diagnosis of liver diseases in dogs and cats

Various techniques utilized for the clinical investigation of small animal patients with signs of liver disease are discussed. The author reviews the evaluation of survey radiographs and selected radiographic contrast techniques, such as cholecystography. The author also outlines the basic principles of hepatic ultrasonography and includes examples of normal and abnormal hepatic ultrasonograms to demonstrate the application of this new imaging modality to the diagnosis of liver diseases.