Diagnosis of chronic active hepatitis in a miniature schnauzer

Abstract

A 12-year-old male castrated miniature schnauzer was presented with a history of abdominal distension. Serum biochemical analysis and abdominal ultrasonography indicated hepatic disease. A wedge biopsy provided a diagnosis of chronic active hepatitis. A therapeutic regime was initiated to improve the quality of life and slow the progression of this disease is described.

A 12-year-old, castrated male, miniature schnauzer was presented to the Western College of Veterinary Medicine (WCVM) with a 6-day history of abdominal distension. The dog had been bright, alert, and eating normally prior to presentation. On physical examination, the abdomen was severely distended and had a palpable fluid wave. The dog was tachycardic (168 beats/min) and had a grade 2/5 systolic murmur. No other significant abnormalities were noted.

Lactated Ringer’s solution was administered because of an initial concern about gastric dilation and volvulus; the dog was then taken for thoracic and abdominal radiography. Abdominal radiographs revealed that the abdomen contained a large volume of peritoneal effusion that obscured most structures. The pylorus was displaced caudally, suggesting possible enlargement of the right lobe of the liver. There were also multiple calculi in the urinary bladder. The thoracic radiographs appeared to be normal.

A blood sample was collected and submitted for a complete blood (cell) count (CBC) (Abbott Cell-Dyn 3500R; Abbott Laboratories, Saint-Laurent, Quebec) and serum biochemical panel (Roche Hitachi 912; Roche Hitachi, Montreal, Quebec). The CBC showed no significant abnormalities. Serum biochemical analysis revealed a mild hyperglycemia (7.1 mmol/L; reference range, 3.1 to 6.3 mmol/L), likely due to stress. Alkaline phosphatase (ALP) (1907 mmol/L; reference range 9 to 90 mmol/L), alanine aminotransferase (ALT) (274 mmol/L; reference range 19 to 59 mmol/L), and sorbital dehydrogenase (SDH) (10 mmol/L; reference range 0 to 4 mmol/L) were elevated, which together strongly suggested hepatobiliary disease. A urine sample, collected via a urinary catheter, had no significant abnormalities on urinalysis and no bacterial growth on urinary culture.

On ultrasonography of the abdomen, a large volume of anechoic peritoneal effusion, which obscured the stomach and intestines, was observed. The central part of the liver contained a large distinct area, measuring 8.53 cm by 8.91 cm, that was very heterogeneous and composed of many cavitary anechoic areas interspersed between hyperechoic and hypoechoic areas. Additionally, a small hypoechoic mass, measuring 1.12 cm by 1.23 cm, was visible in the ventral caudal lobe of the liver. The spleen was mildly heterogeneous with a small hypoechoic mass, measuring 0.918 cm by 0.584 cm, located in the mid-body. No other abdominal abnormalities were noted.

Cardiac ultrasonography was carried out because of the systolic murmur. There was moderate smooth thickening of the mitral valve leaflets and slight regurgitation, consistent with mitral insufficiency due to endocardiosis. The left ventricle was slightly dilated, but the left atrium was not significantly enlarged.

A sample of the peritoneal effusion was obtained by abdominocentosis for analysis. The fluid was slightly cloudy, pale yellow, and slightly blood tinged; it was categorized as a modified transudate with a nucleated cell count of 1.86 × 10⁹ cells/mL, a red blood cell count of 0.025 × 10¹² cells/mL, total solids of 48 g/L, and a specific gravity of 1.031. The cells were primarily activated macrophages, many of which contained leukocytes and erythrocytes. No organisms or neoplastic cells were seen. The most likely causes of a modified transudate in the abdomen are cardiac disease and hepatic disease. Cardiac disease can cause it through increased vascular volume, secondary to activation of the renin-angiotensin-aldosterone system (1). Liver disease can cause it through portal vein hypertension or hypoproteinemia due to decreased albumin production (1). In this case, hepatic disease seemed the likelier cause, since there was no anatomical evidence of significant cardiac disease on thoracic radiographs and cardiac ultrasonographs.

Fine needle aspirates of the liver were taken by using a 22-gauge needle with ultrasonic guidance. Smears were of low cellularity and contained normal hepatocytes, numerous erythrocytes, leukocytes, and platelet clumps in the background, consistent with peripheral blood. There was no evidence of neoplastic cells in the smears. The most likely differential diagnoses were primary hepatic neoplasia, neoplastic metastases to the liver, nodular hyperplasia, or chronic hepatitis, but further diagnostic work was needed to confirm a diagnosis.

Prior to obtaining percutaneous needle biopsies of the large abnormal area of the liver, a blood sample was taken to evaluate clotting times, because there is potential for prolonged clotting times with hepatic disease, since clotting factors are synthesized in the liver. Hemorrhage is always a possible consequence of needle biopsies, which may be exacerbated with alterations in clotting pathways (2). The prothrombin time (PT) was within reference range (8.3 s; reference range, 7.5 to 9.9 s), as was the partial thromboplastin time (PTT) (12.5 s; reference range, 9.6 to 13.8 s), so the dog was considered to be a stable candidate for needle biopsies. The dog was sedated with acepromazine (0.05 mg/kg bodyweight [BW]) and oxymorphone (0.05 mg/kg BW) (Numorphan; Bristol-Myers Squibb Canada, Montreal, Quebec), administered IM. By using ultrasonography to focus on the large abnormal area, 3 percutaneous liver biopsies were obtained with a Tru-Cut device (Travenol Laboratories, Deerfield, Illinois, USA) from the left lobe of the liver.

The biopsied samples consisted predominantly of clotted blood, with small areas of normal hepatocytes and mature collagenous connective tissue, and were considered to be nondiagnostic because of the large amount of blood and the small amount of hepatic tissue present.

The dog was administered spironolactone, 1 mg/kg BW, PO, q12h, and furosemide (Salix; Intervet Canada, Whitby, Ontario), 0.5 mg/kg BW, PO, q12h, in order to decrease the peritoneal effusion (3), and hydromorphone (Hydromorphone; Sabex), SC, as needed, for pain control. Phlebitis developed at the site of the cephalic catheter, so ampicillin (Novo-ampicillin; Novopharm, Toronto, Ontario), 22 mg/kg BW, IV, q6h, was administered. Prophylactic sucralfate, 0.5g, PO, q12h, and ranitidine (Zantac; GlaxoSmithKline, Mississauga, Ontario), 1 mg/kg BW, IV, q24h, were given to protect against gastric ulceration that may be induced by hepatic disease (3).

Three days after the initial blood analysis, a second CBC and serum biochemical analysis were carried out. The results of the CBC demonstrated a moderate leukocytosis (28.4 × 10⁹ cells/L; reference range 4.80 to 13.9 ×10⁹ cells/L), characterized by a moderate neutrophilia (22.72 × 10⁹ cells/L; reference range 3.0 to 10.0 × 10⁹ cells/L) with a mild left shift (1.988 × 10⁹ cells/L; reference range 0.0 to 0.1 × 10⁹ cells/L), likely due to inflammation as a result of the phlebitis, the fine needle aspirates, and the percutaneous needle biopsies. Results of the serum biochemical analysis revealed a mild hyperglycemia (8.4 mmol/L; reference range 3.1 to 6.3 mmol/L), probably persisting due to stress. A mild hyperbilirubinemia (7 μmol/L; reference range 1 to 4 μmol/L) was present, indicating hepatocellular disease, which was consistent with the clinical status. There was also a mild hypoproteinemia (47 g/L; reference range 55 to 71 g/L), characterized by a mild hypoalbuminemia (24 g/L; reference range 28 to 38 g/L) with normal globulin levels. The probable mechanism for the hypoproteinemia in this case was decreased production of albumin by the liver. Protein loss into a third space, such as the peritoneal cavity, was less likely because of the relatively low protein in the abdominal transudate. There was no significant change in the liver enzymes from the previous samples.

The dog was now considered to be a stable candidate for surgery, and a laparotomy was carried out to examine the liver and obtain surgical wedge biopsies. He was sedated with fentanyl, 10 μg/kg BW, IV, and diazepam (Diazepam; Sabex, Boucherville, Quebec), 0.1 mg/kg BW, IV; induced with propofol (Rapinovet; Schering Plough, Pointe Claire, Quebec); and maintained with isoflurane (Aerrone; Baxter, Mississauga, Ontario) and oxygen. He was placed on a fentanyl constant rate infusion (CRI), 0.5 to 1.0 μg/kg/BW/min, during surgery to decrease the isoflurane required to maintain a surgical plane of anesthesia. The significant findings on abdominal exploration included an enlarged liver with a grossly nodular appearance and little visible normal hepatic tissue. There was 1 nodule on the spleen, which appeared consistent with benign nodular hyperplasia. Several wedge biopsies of representative hepatic tissue were taken by using a ligature (“guillotine”) technique (4). No other significant abnormalities were seen in the abdomen.

Examination of wedge biopsies revealed chronic active hepatitis that was multifocal and moderate with prominent telangiectasis, which was the likely cause of the hypoechoic, cavitated areas that were visible on ultrasonography (5). There was also hepatic atrophy that was multifocal, chronic, and moderate to severe. The pattern of liver lesions in this case was also suggestive of peliosis hepatis, which is a vasculoproliferative disorder causing cystic blood-filled spaces in the liver (5). Some proposed causes of this pattern of damage include vascular anomalies, hypoxemia, ischemia, and hypervolemia (5). Several toxic or therapeutic substances, such as pyrrolizidine alkaloids, azathioprine, medroxyprogesterone acetate, and corticosteroids, have been shown to induce peliosis hepatis in various species (5). A recently identified cause of peliosis hepatis in dogs is parasitic infection with Bartonella henselae (6). There have been no reported cases of this in Canada, but blood samples have been saved from this case for future investigation into Bartonella henselae as a possible cause for this dog’s pathologic condition. Most often, no cause is determined for this pattern of liver lesions, which is true with most cases of chronic active hepatitis (5,7).

Many therapeutic regimes have been suggested for use in chronic active hepatitis, but results from clinical trials are limited, so most information comes from individual cases (3). In this case, a postoperative therapeutic regimen to slow the progression of the liver damage and to treat secondary effects of chronic active hepatitis was followed. The diuretic administration that was started previously was maintained to decrease the peritoneal effusion. The antifibrotic drug colchicine (Colchicine; Abbott, North Chicago, Illinois) was given at 0.03 mg/kg BW, PO, q24h. Fibrosis is a major destructive feature of chronic active hepatitis and contributes to some of the secondary effects seen with chronic hepatitis (3). Colchicine is believed to slow hepatic fibrosis by inhibiting procollagen secretion, and it may have hepatoprotective effects through stabilization of hepatocyte plasma membranes (3). Several hepatoprotective drugs were also prescribed to mitigate the ongoing hepatocyte damage caused by free radicals and bile salts, which are increased due to cholestasis associated with the liver lesions (3). These were ursodeoxycholic acid (Actigall; Novartis, Mississauga, Ontario), 10 mg/kg, BW, PO, q24h; vitamin E at 400 i.u. PO, q24h; and s-adenosyl-l-methionine (Denosyl 5D4; Vétoquinol, Lavaltrie, Quebec), 18 mg/kg BW, PO, q12h. The antifibrotic and hepatoprotective treatment will be lifelong, provided the dog tolerates the drugs. The dog will be checked periodically to monitor the progression of his chronic active hepatitis and the effectiveness of the therapy through clinical visits and repeated biochemical panels.

This case demonstrates the necessity for thorough diagnostic procedures when there is a suspicion of liver disease. Based on a biochemical panel and medical imaging procedures, it was not possible to differentiate among neoplastic disease, chronic hepatitis, or any other potential liver disease.

A definitive diagnosis is essential, as the treatment protocols and prognosis are greatly different for the potential disease processes. In this case, 3 diagnostic procedures for obtaining liver samples were employed: fine needle aspiration, percutaneous needle biopsies, and surgical wedge biopsies. Fine needle aspirates are commonly used as an initial means for obtaining hepatic tissue due to the minimal invasiveness of the procedure, very small risk of complications, and the minimal cost to the client (8). They can often be performed without sedation, making them a quick procedure in practice. They are most useful in liver disease with focal lesions, provided that ultrasonographic guidance is used (8). They do not provide any information on the architecture of the liver, as only cytological smears are obtained (8). Cytologic examination has minimal value in assessing hepatic inflammation, as the liver is highly vascular, so the majority of samples contain leukocytes from peripheral blood (9).

If fine needle aspirates are not diagnostic, or if diffuse liver disease is suspected, percutaneous needle biopsies may be attempted (8). Definitive diagnosis in humans regarding the architecture of the hepatic parenchymal typically requires a sample spanning 5 portal triads to make accurate judgments regarding hepatobiliary and vascular structures, as well as the distribution of the lesions, and it is likely that requirements are similar in veterinary medicine (10). One study evaluating the Tru Cut biopsy instrument found a range of 4.67 to 5.33 portal triads per sample, so many of these samples provided sufficient information to reach a morphological diagnosis (11). Percutaneous biopsy techniques are popular due to the low frequency of complications and minimal invasiveness, compared with surgical biopsies, while still providing a potential for a morphological diagnosis (10). This technique is limited by significant fibrous tissue, which can impair the ability to collect a useful sample (10).

Wedge biopsies are often essential to characterizing liver lesions accurately, but they should only be performed if the patient is stable enough to tolerate the procedure (2). It is a more invasive technique than needle biopsies, particularly when done in conjunction with an exploratory laparotomy; however, it does permit direct examination of the liver and other abdominal organs, and does allow representative biopsy sites to be chosen. Wedge biopsy samples are longer than percutaneous needle biopsies and have a median surface area 4 times larger, which is beneficial, as smaller sample sizes increase the risk of sampling error (10). One prospective study determined that the morphological diagnosis for a needle biopsy agreed with the definitive diagnosis determined by wedge biopsies in only 48% of animals tested (10). Incorrect morphological diagnosis based on needle biopsies may lead to erroneous diagnosis of the disease process and inappropriate treatment of the patient. Once a conclusive diagnosis has been made through whatever means necessary, appropriate treatment can be initiated.