Hilar Liver Resection in Dogs

Objective— To describe hepatic vasculobiliary anatomy important to hilar liver lobe resection in the dog.
Study Design— Experimental study.
Animals— Canine cadavers (n=7).
Methods— The vasculobiliary system of 7 fresh canine livers was injected with a polymer. The parenchyma was dissected at the level of the hilus to determine the vascular and biliary supply to each liver lobe, and then macerated with a corrosion preparation. The information gathered was used to describe a surgical approach for hilar liver lobe resection.
Results— Each liver lobe had a single hepatic artery and biliary duct. The location of these structures was consistent, although minor variations existed (dorsal versus ventral to the lobar portal vein) in the left lateral lobe and papillary process in 2 specimens. Most liver lobes (34/49) were supplied by 1 lobar portal vein and drained by 1 lobar hepatic vein (39/49). The location of the portal and hepatic veins was consistent among specimens.
Conclusions— The left division is the most mobile of the liver lobes and each lobe can be removed separately or en bloc. Because of the location of the hepatic veins, the central division is best removed as a single unit. The right lateral lobe can be removed individually or together with the caudate process. The papillary process is removed by itself.
Clinical Relevance— A hilar liver lobectomy technique can provide an alternative approach to conventional procedures for tumors that encroach upon the hilus of the liver.     

Metastatic Tumor in Pregnancy: Placental Germ Cell Tumor With Metastasis to the Foal

A placental mass was observed in an otherwise-healthy Quarter Horse mare; subsequently, the mare's 52-day-old foal was examined because of hind limb ataxia, urinary incontinence, and raised lesions of the distal limbs. Clinical and biochemical findings were supportive of liver disease and lumbosacral injury. Ultrasonographic evaluation of the abdomen suggested a liver mass, which was confirmed with computed tomography (CT) and determined to be neoplastic via histopathologic evaluation of a liver biopsy sample. Initial histopathology suggested a germ cell tumor. Regions of lysis affecting both femurs and third metacarpal bones and a complete oblique sagittal fracture through the body of the first sacral vertebra were present on CT. Supportive care was provided until CT confirmation of diffuse hepatic neoplasia and vertebral fracture. Necropsy revealed a large multinodular mass within the liver and a pathologic fracture of the first sacral vertebral body. Histopathologic comparison between neoplastic cells examined from the placenta and foal confirmed metastases of a germ cell tumor. Placental tumors are rare in all species; however, when noted in horses, clinicians should be aware of the possibility of metastatic spread to the foal.     

Use of contrast ultrasonography in the diagnosis of metastatic feline visceral haemangiosarcoma

A 12-year-old cat was presented for investigation of weight loss and inappetence. Radiography and conventional grey-scale ultrasonography showed a large mid-body splenic mass. Contrast enhanced ultrasonography of the liver demonstrated a hypoechoic left lateral lobe nodular mass during the peak and late portal-phases of liver enhancement. Histopathology of the splenic mass and hepatic nodular mass confirmed haemangiosarcoma. The use of ultrasound microbubble contrast media in the diagnosis of hepatic metastasis in the cat has not been previously reported in the cat.     

Erythrocytosis and pleural effusion associated with a hepatoblastoma in a Thoroughbred yearling

A 10-month-old Thoroughbred filly was presented with a 2-month history of recurrent fever and pleural effusion. Major clinical findings were pyrexia and congested mucous membranes. Clinical pathology tests revealed an erythrocytosis, hyperfibrinogenaemia and hyperglobulinaemia. Pleural fluid was seen on ultrasonographic examination of the thorax and analysis of a thoracocentesis sample indicated a lymphocytic, modified transudate. A transtracheal aspirate was normal. The erythrocytosis persisted despite IV fluid therapy. Arterial blood gas analysis and bone marrow aspirate were normal. These findings were indicative of secondary inappropriate erythrocytosis. Ultrasonographic examination of the abdomen showed a large encapsulated heterogeneous mass in the left lobe of the liver. Histopathological evaluation of a biopsy of the mass was indicative of a hepatic carcinoma. The filly was euthanased and necropsy confirmed the presence of a hepatic tumour with no evidence of systemic metastasis. Further histopathological evaluation confirmed the tumour to be an embryonal macrotrabecular epithelial-type hepatoblastoma, a type of hepatoblastoma that has not previously been reported in a horse.     

Anatomical evaluation of hepatic vascular system in healthy beagles using X-ray contrast computed tomography

Liver contrast X-ray computed tomography (CT) has been used for evaluation of hepatic vessels for liver transplantation, liver lobectomy, interventional radiology and diagnosis of hepatocellular carcinoma in humans. However, there remains scant available anatomical information on normal hepatic vessels in the veterinary field. In this study, visualization of hepatic vessels was evaluated in 32 normal beagle dogs by X-ray contrast CT using triple phase images. The following hepatic vessels were clearly visualized: arterial, portal and hepatic veins. With regards to the running patterns of the portal vein and hepatic vein, there were no significant differences between the dogs. However, the hepatic artery exhibited some differences in each dog. In particular, the hepatic artery of the quadrate lobe and the right lateral lobe had many running patterns. The results of the present study could be useful for veterinary diagnosis, surgery and interventional radiology.     

Gross Anatomy of the Ringed Seal (Pusa hispida) Gastro‐Intestinal Tract

The gross anatomical structure of the ringed seal (Pusa hispida) gastrointestinal tract is poorly described and often veterinary anatomical terminology is not used. Although the basic abdominal visceral pattern corresponded to domestic carnivores, significant differences were noted. The stomach was an elongated sharply bent tube (u‐shaped) with the pylorus and fundus juxtaposed. The elongated jejunum measured up to 15.6 times body length and had 37 jejunal arteries from the cranial mesenteric artery. The pancreas was asymmetrical with a small right lobe and a large left lobe. The unusually short greater omentum negated formation of deep and superficial leaves. The most remarkable difference was the separation of the liver parenchyma into three physically separate masses, held together by hepatic ducts, veins and arteries. The topography and position of the liver was dependent on the amount of blood in the hepatic sinus (distended hepatic veins and hepatic portion of vena cava). Thus, as the hepatic sinus filled, the lateral liver masses separate from the central mass by moving caudolaterally. This was facilitated by modified coronary and triangular ligaments which did not attach directly to the liver, but instead to the hepatic sinus. These anatomical adaptations are apparently advantageous to ringed seal's survival in a deep marine environment.     

Ataxia and weakness as uncommon primary manifestations of hepatic encephalopathy in a 15‐year‐old trotter gelding

A 15‐year‐old trotter gelding was evaluated because of an acute onset of ataxia in all 4 limbs. There was no known history of trauma. The gelding showed grade 2/5 ataxia in all 4 limbs, which was localised after clinical neurological examination to the cervical vertebral spinal cord. Initial therapy consisted of oral anti‐inflammatory doses of prednisolone and antimicrobial treatment with potentiated sulphonamides. The ataxia progressed to grade 3/5 at Day 10 of hospitalisation. Additionally, the horse was slightly depressed and showed spontaneous yawning during examination. Facial sensation was blunted. Blood chemistry revealed a marked elevation of liver specific enzymes and blood ammonia levels. Transcutaneous abdominal ultrasonography revealed hepatomegaly. Due to a guarded prognosis, the horse was subjected to euthanasia. At necropsy the left lateral liver lobe was markedly enlarged and showed a firm texture, whereas the cranial part and the right and quadratic liver lobe displayed a severe and diffuse atrophy. Histopathologically, the left lateral liver lobe revealed a moderate to severe cirrhosis with a severe, diffuse hepatocellular iron‐accumulation. Increased numbers of Alzheimer type II astrocytes in the cerebral cortex and cerebral white matter vacuolisation were indicative for encephalopathy. These findings were interpreted as haemosiderosis and cirrhosis of the liver with consecutive hepatic encephalopathy. Aetiologically, haemosiderosis should be considered as a cause of liver cirrhosis with consecutive hepatic encephalopathy. Although hepatic encephalopathy in horses usually presents with predominating cerebral signs, it has to be taken into account as a differential diagnosis in cases of acute onset generalised ataxia.     

Long-term survival in a dog with primary hepatic neuroendocrine tumor treated with toceranib phosphate

Primary hepatic neuroendocrine tumors (PHNETs) are rare in dogs, and limited information exists about the treatment of these tumors. A 12-year-old castrated male French bulldog was presented to our clinic with gastrointestinal signs. Diagnostic tests revealed increased hepatic enzyme levels, a mass in the hepatic quadrate lobe, multiple intrahepatic nodules, and enlarged hepatic hilar lymph nodes. The liver mass was diagnosed cytologically as a malignant epithelial tumor suspected to be of neuroendocrine origin. The dog was treated with single-agent toceranib phosphate (TOC) and survived 25.1 months after the initial presentation. On necropsy, a liver mass was found and was subsequently diagnosed as a PHNET on histopathology. To the best of our knowledge, this is the first report of long-term survival in a dog with PHNET treated with TOC.     

Vascular Anatomy of Canine Hepatic Venous System: A Basis for Liver Surgery

Detailed knowledge of the vascular anatomy is important for improving surgical approaches to the liver. Twelve canine livers were skeletonized to describe the anatomy of their portal and hepatic veins in details. Our data suggest that the liver can be divided into two sections, three divisions, seven lobes and two to four sub‐lobes. This differs from the classic division into four lobes, four sub‐lobes and two processes. The right section was perfused by the right portal branch and drained by independent hepatic veins, while most of the left section, perfused by the left portal branch, was drained by the main hepatic vein deriving from the middle and the left hepatic vein confluence. Part of the right medial lobe, and in some cases the papillary process of the caudate lobe, drained directly into the caudal vena cava. A proper right hepatic vein draining blood from more than one lobe was never observed. Portal connections between the quadrate and the left medial lobe were frequently recorded. Two sub‐lobes with different portal blood supply and venous drainage could be identified in the right lateral (33.3% of cases) and the left lateral (100% of cases) lobes. From our results, the classic nomenclature of the liver lobes does not reflect their vascularization. Based on similarities between canine lobes and human segments, a new nomenclature is possible and may be less confounding in surgical settings.     

IMAGING DIAGNOSIS—ULTRASONOGRAPHIC AND CT FINDINGS IN A GRAY SEAL (HALICHOERUS GRYPUS) WITH HEPATIC CIRRHOSIS,PYELONEPHRITIS, AND NEPHROLITHIASIS

An immature gray seal was presented with lethargy, weight loss, vomiting and hematuria. Hepatic disease and urinary tract infection were suspected. Abdominal ultrasound showed hyperechoic structures with marked acoustic shadowing spread throughout both kidneys, but incomplete visualization of the liver. Abdominal CT showed mineral densities scattered throughout both kidneys and poor delineation of the liver. Due to the poor quality of life, the seal was euthanized. Postmortem examination showed ammonium urate nephroliths, pyelonephritis, and hepatic cirrhosis. This case report emphasizes the difficulty of characterizing liver disease with conventional 2D‐ultrasound and CT in a deep‐chested animal with minimal intra‐abdominal fat.     

IMAGING DIAGNOSIS—NUCLEAR SCINTIGRAPHIC,RADIOLOGICAL, AND PATHOLOGIC CHARACTERISTICS OF METASTATIC PILOMATRICOMA IN A DOG

A 6‐year‐old castrated Goldendoodle dog was presented for left‐sided lameness of 3 weeks’ duration. Focal, moderate to marked increased ^99mTc‐methylene diphosphonate (^99mTc‐MDP) uptake was detected in the right caudal lung lobe, caudal angle of the left scapula, and the distal aspect of the left femur with whole body bone phase scintigraphy. Radiographs identified a well‐circumscribed, oval‐shaped soft tissue opaque mass in the right caudal lung lobe; a suspect oval‐shaped osteolytic lesion in the proximal third of the left scapula; and an osteolytic lesion in the distal aspect of the left femur. Metastatic pilomatricoma was confirmed histologically at all three sites.     

Temporal Evolution of Hepatic Anatomy During Gestation and Growth in the Sheep

In mammals, the liver undergoes a series of spectacular anatomical changes during development, particularly in domestic ruminants. In all domestic mammals, the liver retracts cranially until it reaches its definitive diaphragmatic position; however, in the sheep, it also withdraws from the entire left side of the diaphragm and seems to rotate through 180°. An anatomical study reveals that the hepatic conformation evolves very little during this topographical change. The latter occurs in two phases: an initial phase of marked regression of the left lobe, which starts from the beginning of the foetal period (44th day of gestation), followed by marked regression of the entire liver, which starts between the 90th and 117th days and ends between the 2nd and 3rd month of life. The path of hepatic regression is dictated by the particular layout of the liver's attachments in the sheep. The left triangular ligament, which holds the L lobe to the left in other species, is almost completely absent in the sheep, whilst the right lobe is fixed to the top of the diaphragm. As the liver regresses, the right lobe therefore draws the left lobe with it to the right‐hand side. A statistical study shows constant regression of the hepatic surface area during the topographical evolution of the liver, with a particularly marked and sudden reduction between the end of the 4th month and the middle of the 5th month of gestation. It also shows that the regression of the left lobe is consistently greater than that of the right lobe and that the topographical regression of the liver cannot be predicted by measuring the weight of the liver, which behaves independently to the surface area of the liver.     

COMPARISON BETWEEN COMPUTED TOMOGRAPHY AND 99m TC‐ PERTECHNETATE SCINTIGRAPHY CHARACTERISTICS OF THE THYROID GLAND IN CATS WITH HYPERTHYROIDISM

Scintigraphy is currently the reference standard for diagnosing feline hyperthyroidism; however, computed tomography (CT) is more widely available in veterinary practice. The purposes of this prospective study were to describe the CT appearance of thyroid glands in cats with hyperthyroidism and compare CT findings with findings from ^99mTc–pertechnetate scintigraphy. Twenty‐five adult hyperthyroid cats were included. Plain CT images were acquired for each cat and the following characteristics recorded for each thyroid lobe: visibility, delineation, position, attenuation, shape, and subjective size. Scintigraphic images were also acquired and the following characteristics recorded: radiopharmaceutical uptake, delineation, ectopic foci, shape, and subjective size. In CT images, thyroid lobes were most commonly found between the second and fourth cervical vertebrae, dorsolateral to the trachea. Affected thyroid lobes (based on scintigraphy reference standard) were most commonly oval and moderately enlarged in CT images. A heterogeneous attenuation pattern (isoattenuating to adjacent soft tissues with hypo‐ and hyperattenuating foci) was most commonly found in affected thyroid lobes. A positive correlation (P < 0.01) was identified between CT and scintigraphy for left‐to‐right thyroid lobe size relationship and subjective size of the larger thyroid lobe. The CT estimated mass was significantly higher (median = 148.8; range = [0;357.6]) for the more active thyroid lobe compared to the less active thyroid lobe (median = 84.6; range = [0;312.3]); (W = 154; P < 0.01). Findings indicated that CT may not reliably differentiate unilateral vs. bilateral hyperthyroidism in cats; however, CT may be a reliable alternative test for correctly identifying the more active thyroid lobe.     

Use of computed tomography and minimum intensity projection in the detection of lobar pneumonia mimicking lung lobe torsion in a dog

A 10‐year‐old female spayed Dachshund was referred with progressive coughing for 1 month. The dog was tentatively diagnosed with right middle lung torsion based on pleural effusion, vesicular emphysema, abruptly ending bronchus in consolidated right middle lung, and no contrast enhancement of the affected lobe on radiography and computed tomography (CT). There was no evidence of torsion upon thoracotomy, and histological examination confirmed lobar pneumonia. The CT images were reevaluated using minimum intensity projection and revealed normal bronchial courses. The minimum intensity projection technique can be to assist in evaluation of the bronchial tree for dogs with suspected lung lobe torsion and other pulmonary diseases.     

ASSOCIATIONS BETWEEN DUAL‐PHASE COMPUTED TOMOGRAPHY FEATURES AND HISTOPATHOLOGIC DIAGNOSES IN 52 DOGS WITH HEPATIC OR SPLENIC MASSES

Ability to noninvasively differentiate malignant from nonmalignant abdominal masses would aid clinical decision making. The aim of this retrospective, cross‐sectional study was to identify features in dual‐phase computed tomographic (CT) studies that could be used to distinguish malignant from nonmalignant hepatic and splenic masses in dogs. Medical records were searched for dogs that had an abdominal dual‐phase CT examination, a hepatic or splenic mass, and subsequent histopathologic diagnosis. Computed tomographic images for all included dogs were acquired prior to and <30 s (early phase) and >60 s (delayed phase) after intravenous contrast administration. Fifty‐two dogs with 55 masses were studied: 24 hepatic, including 14 (58%) malignant and 10 (42%) non‐malignant; 31 splenic, including 18 (58%) malignant and 13 (42%) nonmalignant. There was substantial overlap in the pre‐ and postcontrast CT features of malignant and nonmalignant hepatic and splenic masses. Regardless of histologic diagnosis, hepatic masses most frequently showed marked, generalized enhancement in early phase images that persisted in the delayed phase. Splenic hemangiosarcoma and nodular hyperplastic lesions most frequently showed marked, generalized enhancement in early phase images that persisted in delayed images whereas most splenic hematomas had slight enhancement in early phase images. All splenic hematomas and 77% of the hemangiosarcomas had contrast accumulation compatible with active hemorrhage. There were no other significant differences in quantitative or categorical CT data between malignant and nonmalignant hepatic or splenic masses. Dual‐phase CT of dogs with hepatic or splenic masses provides limited specific diagnostic information.     

Clinical and histologic outcome in a dog surviving massive hepatic necrosis

This report describes the clinical and histologic recovery of a 2‐year‐old mixed‐breed dog presented with hypovolemic shock, markedly increased serum alanine amino transferase activity, and hemoabdomen. Emergency exploratory surgery revealed a friable liver with multiple capsule hemorrhages necessitating removal of the left lateral lobe. Histologic evaluation showed acute massive hepatic necrosis with centrilobular and midzonal distribution. The dog survived, and all monitored laboratory values normalized within 7 weeks. A liver biopsy taken 8 weeks after presentation revealed normal hepatic architecture with a few, randomly distributed neutrophilic foci. Follow‐up included intermittent determination of liver variables including liver function tests for a period of 7 years. The dog's health status, and all test results remained normal during this time. Complete recovery and good long‐term quality of life after life‐threatening acute liver failure secondary to massive hepatic necrosis is possible in dogs.     

Negative hepatic computed tomographic attenuation pattern in a dog with vacuolar hepatopathy and hepatic fat accumulation secondary to cushing's syndrome

This report describes an unusual computed tomographic (CT) hepatic pattern, characterized by negative attenuation values (from –19.59 to –28.85 Hounsfield Units, HU) in a canine patient with severe Cushing's syndrome. Attenuation values of the splenic parenchyma (63.26 HU) and abdominal fat (–118.34 HU) were within normal limits. The negative hepatic attenuation values allowed a CT diagnosis of severe hepatic fatty infiltration that was subsequently confirmed by tissue‐core biopsy and histopathological examination.     

ANATOMY OF THE PORTAL AND HEPATIC VEINS OF THE DOG: A BASIS FOR SYSTEMATIC EVALUATION OF THE LIVER BY ULTRASONOGRAPHY

The objective of this study was to define, in detail, the anatomy of the portal and hepatic veins in the dog in order to establish a procedure for the systematic evaluation of the liver by ultrasonography. Anatomical details were obtained from the formalin fixed livers of ten dogs. The hepatic and portal veins were removed intact from these livers so that a detailed pattern of distribution could be established and the numbers of branches could be counted. Silastic casts were also made of the hepatic and portal veins of two livers, one in situ and one in which it had been removed. The former was to enable the relationship of the portal to the hepatic veins to be established as closely as possible within the animal and the other to provide a model of the distribution of each venous system within the liver. Contrast medium was infused into two other livers and radiographs taken to establish the relationship of each branch to each lobe. It was found that there was a consistent pattern of venous branching to each lobe of the liver in the dog with little variation between individual specimens. All liver lobes contained definite venous branches so that the left lateral and medial, quadrate, right medial and lateral, caudate and papillary veins could be distinguished in each venous system. We believe that an appreciation of this venous distribution will aid in the systematic evaluation of the liver during ultrasonography by enabling identification of each liver lobe. It should be of value for differentiating portal from hepatic veins and veins from dilated bile ducts.     

Hepatic lobe torsion in 3 dogs and a cat

OBJECTIVE: To describe the clinical features of hepatic lobe torsions in 3 dogs and 1 cat. STUDY DESIGN: Retrospective clinical study. ANIMALS: Three client-owned dogs and 1 client-owned cat. METHODS: Medical records were reviewed, and information regarding signalment, clinical signs, physical-exam findings, diagnostic tests performed, treatment, outcome, and follow-up was retrieved. RESULTS: Clinical signs existed for 4 hours to 1 week before examination. Signs were nonspecific in 2 animals that did not have an obvious cause for the hepatic torsion. These signs consisted of lethargy (2), polyuria/polydypsia (2), and anorexia (1). In the other 2 animals, signs were suggestive of the underlying cause of the hepatic lobe torsion. In 1 dog, the torsion was associated with a traumatic diaphragmatic hernia. The cat had a concurrent hemoabdomen secondary to a ruptured hepatocellular carcinoma. Bloodwork abnormalities were nonspecific. Twisted liver lobes included the left lateral lobe (2), the caudate lobe (1), and the right medial lobe (1). Surgical resection (2) or repositioning (1) of the affected liver lobe was attempted in the 3 dogs, and was successful in 2. CONCLUSION: Hepatic lobe torsion is a rare problem but has been reported in humans, rabbits, dogs, pigs, a cat, and a horse. The left lateral liver lobe is most frequently affected. This condition may be idiopathic or associated with neoplasia or absence of ligamentous support (congenital or traumatic) to the liver. CLINICAL RELEVANCE: Prompt surgical resection or repositioning of the involved liver lobe can lead to a successful outcome, avoiding the deleterious effects of venous obstruction such as thrombosis and subsequent necrosis.