Hepatic abscesses in dogs are rare (2,4). Their diagnosis is sometimes difficult owing to non-specific clinical signs and diagnostic characteristics (4,11,12). Although there are several reports on the diagnosis and treatment of hepatic abscesses in dogs (4,5,7,9,11,12), there are no reports on disease progression-associated diagnostic procedures, especially diagnostic imaging and blood tests, and treatment of canine hepatic abscesses. In this case report, we described the disease progression in a dog with hepatic abscesses.

A 15-year-old spayed female Yorkshire Terrier was referred to our hospital for evaluation following a history of anorexia and lethargy. Approximately 10 days prior, the patient was brought to a local animal hospital because of three episodes of vomiting and reported lethargy. At that time, no abnormal findings were observed on abdominal radiography or ultrasonography. Blood tests confirmed leukocytosis and increased renal parameters and hepatocyte levels. Thus, the patient was administered non-specific supportive treatments with intravenous (IV) fluids, hepatoprotective agents, renal protectants, and antibiotics for 10 days at the local animal hospital. However, the patient’s condition did not improve. The patient was subsequently referred to our hospital. Physical examination revealed abdominal pain and a slightly increased rectal temperature (39°C). A complete blood cell count (CBC) revealed moderate non-regenerative anemia (hematocrit [HCT]: 27.5% reference range [RR]: 36.9-55.0%), severe thrombocytopenia (platelet count: 61 × 10³/μL, RR: 117-490 × 10³/μL), and a moderately increased number of white blood cells (WBC: 24 × 10³/μL, RR: 6.6-17.0 × 10³/μL). Results of serum biochemistry profile revealed increased alkaline phosphatase (ALP: 1371 U/L, RR: 47-254 U/L), aspartate aminotransferase (AST: 53 U/L, RR: 17-44 U/L), blood urea nitrogen (BUN; 41.2 mg/dL, RR: 9.2-29.2 mg/dL), creatinine (1.46 mg/dL, RR: 0.4-1.4 mg/dL), phosphorus (7.9 mg/dL, RR: 1.9-5.0 mg/dL), and globulin level (4.7 g/dL, RR: 1.6-3.7 g/dL). Abdominal radiography showed hepatomegaly. Abdominal ultrasonography revealed multiple hypoechoic cystic structures, ranging from a few millimeters to 22 mm in diameter, and hyperechoic parenchyma in the left hepatic lobe (Fig. 1A). Oral administration of amoxicillin-clavulanate (13.75 mg/kg P.O. twice daily; Clavamox; Pfizer), metronidazole (15 mg/kg P.O. twice daily; Flasinyl; HK inno.N), tramadol (4 mg/kg P.O. twice daily; Tridol; Yuhan pharmaceutical), gastroprotective agents, and hepatoprotective agents was initiated, and the patient was monitored. During the three days of monitoring, there was one episode of vomiting, but the owner reported that the dog ate some food and showed some improvement. Thus, maropitant (2 mg/kg P.O. once daily; Cerenia; Zoetis) was added to the prescription as an antiemetic agent. However, the following day, the patient’s condition worsened, the HCT decreased to 25.6%, and the WBC count increased to 39.7 × 10³/μL. Her platelet count measured 144 × 10³/μL. Abdominal ultrasound revealed that the diameter of the largest cyst had increased to 30 mm and the cyst had changed from hypoechoic to hyperechoic (Fig. 1B). The size and echogenicity of other cysts in the liver were remained unchanged. The owner refused any further diagnostic procedures, including cystocentesis, due to the risk of iatrogenic bleeding and decided to continue active observations. The next day, the dog was brought to our emergency department with severe weakness and a decreased response to external stimuli. Hematologic evaluation revealed increased HCT (28.1%) and WBC (45.7 × 10³/μL) since the last visit. Serum biochemical abnormalities included increased creatinine (1.63 mg/dL) and hyperphosphatemia level (7.8 mg/dL). Abdominal ultrasonography revealed a small amount of free fluid around the largest cyst in the left liver lobe, and the cyst margin was obscure. Increased echogenicity of the perihepatic fat was also observed, but other organs had no abnormalities. After sedation with butorphanol (0.2 mg/kg IV; Butophan; Myungmoon pharmaceutical), cystocentesis was conducted. Cytology of the fluid from the cyst revealed several red blood cells (RBC) and cocci with phagocytosis (Fig. 2). Under general anesthesia with propofol and isoflurane, a CT (AlexionTM, Canon Medical Systems; Japan) scan confirmed a severely enlarged left lateral liver lobe with a multilobulated cystic lesion of 21.6 × 33.6 × 41.7 mm³ in diameter and a few small cysts (Fig. 3). No abnormalities were observed in the right lobe of her liver. Splenic parenchymal revealed heterogeneous contrast enhancement and a slightly enlarged mediastinal lymph node. An aspirated sample of hepatocystic fluid was subjected to culture and antibiotic susceptibility tests. Pending culture results, the patient was treated with ampicillin (20 mg/kg intravenously thrice daily; Penbrex; Yungjin pharmaceutical), metronidazole (15 mg/kg intravenously twice daily; Metrynal; Daihan pharm.), enrofloxacin (10 mg/kg intravenously once daily; Baytril; Bayer), tramadol (4 mg/kg intravenously twice daily; Maritrol; Jeil pharm.), esomeprazole (1 mg/kg intravenously once daily; Nexium; Astrazeneca), maropitant (1 mg/kg intravenously once daily; Cerenia; Zoetis), vitamin K (1.1 mg/kg subcutaneously twice daily; Alpha K1; Cheilbio), and fluid therapy. In consultation with the owner, the surgical procedure was decided the following day. Left lateral lobectomy was performed using the guillotine method. After surgery, the analgesic agent was changed from tramadol to fentanyl (3 μg/kg/h constant infusion rate; Fentanyl; Hanlim pharmaceutical). Eight hours after lobectomy, the HCT had decreased significantly to 20.8%. Therefore, a whole blood transfusion was performed, which increased the HCT to 34.7%. During hospitalization, the WBC count constantly increased. On the third day of hospitalization, the patient’s condition improved and she voluntarily consumed some food. However, her WBC count was high (Table 1). Thus, meropenem (8.5 mg/kg intravenously thrice daily; Meropenem; Dongkwang pharm.) was started. In addition, based on the antibiotic susceptibility test, enrofloxacin (10 mg/kg intravenously once daily; Baytril; Bayer) was changed to levofloxacin (10 mg/kg P.O. once daily; Cravit; Jeil pharm.) (Table 2). After lobectomy, the sample was sent to perform histopathologic examination. The result showed that the findings are most suggestive of a severe bacterial infection. Over 50% of the sections of liver are replaced by large multifocal to confluent regions of brightly eosinophilic lytic necrosis and hemorrhage invested with numerous viable and nonviable neutrophils, eosinophils, fibrin, necrotic cell debris and fewer foamy macrophages. Hepatocytes bordering cystic regions are swollen brightly eosinophilic and necrotic. Although no organisms were detected in histology, cultures are much more sensitive method of detection than histology. Bacterial culture of the liver abscess yielded Enterococcus faecium and Escherichia coli. The dog also presented oliguria with slightly elevated renal parameters. On the fourth day of hospitalization, the WBC count decreased, but the HCT (22%), platelet count (10 × 10³/μL), and albumin concentration (1.4 g/dL, RR: 2.6-4.0 g/dL) also sharply decreased with melena. Despite the second whole blood transfusion, the HCT and platelet count did not increase. After a large amount of bloody stool, one more transfusion was attempted, but 2 hours after the third transfusion, the patient’s SpO2 and blood pressure had declined severely. The patient was unresponsive to emergency drug treatment and died 3 h later.

Table 1 . Hematologic values of the patient.

	Day 0	Day 3	Day 4	Day 5	Day 5	Day 6	Day 7	Day 8	Day 9	Day 9
				Before operation	After operation	After transfusion			Before transfusion	After transfusion
HCT (%)	27.5	25.6	28.1	28.1	20.8	34.7	37.2	29.9	22.0	21.6
WBC (×102/μL)	240	397	457	58.8	26.4	82.1	107.1	83.7	62.7	41.5
PLT (×103/μL)	61			141	113	92	56	36	10	10

HCT, hematocrit; WBC, white blood cell; PLT, platelet..

Table 2 . Antibiotic susceptibility test.

Enterococcus faecium			Escherichia coli
Antibiotic agent	Result		Antibiotic agent	Result
Doxycycline	S		Doxycycline	S
Vancomycin	I		Chloramphenicol	I
Amikacin	R		Amikacin	S
Trimethoprim-Sulfamethazole	R		Trimethoprim-Sulfamethazole	S
Cefotaxim	R		Cefotaxim	S
Cefixime	R		Cefixime	S
Clindamycin	R		Cefalexin	S
Cefazolin	R		Cefazolin	S
Ciproxacin	R		Ciproxacin	S
Meropenem	R		Imipenem	S
Ampicillin	R		Ampicillin	R
Cephalexin	R		Cephalexin	S
Gentamicin	R		Gentamicin	S
Amoxicillin-Clavulanic acid	R		Amoxicillin-Clavulanic acid	I
Cefovacin	R		Cefovacin	S
Enrofloxacin	R		Enrofloxacin	I

S, sensitivity; R, resistance; I, inadequate sensitivity..

Figure 1. Changes of the hepatic lesions in abdominal ultrasound. (A, B) Day 0. (A) Biggest cyst in the ventral left liver lobe. It shows an anechoic feature and 22.0 × 7.2 mm in diameter. (B) Multiple hypoechoic nodules with unclear border and hyperechoic parenchymal regions in dorsal part of left liver lobe. (C) Day 3. Three days later, the cyst was 28.0 × 19.1 mm in diameter and revealed increased echogenicity. (D-F) Day 4. (D) The size of the biggest cyst was slightly increased, and the margin was unclear. Echogenic fluid and materials were also observed in the cyst. (E) Mesentery thickening in the left upper abdomen adjacent to the biggest cyst. (F) Free fluid around the lesions.

Figure 2. Cytology images of the fluid aspirated from the biggest hepatic cyst in the left liver lobe. The aspirate consists of infectious agents (arrowhead), RBC (white arrow), and inflammatory cells (black arrow, neutrophils). Diff-Quik stain, 1000×.

Figure 3. Contrast-enhanced CT images of the liver and spleen in the dog. The transverse image revealed splenic parenchymal heterogeneity (white arrow) and multiple lesions in the left lateral liver lobe. The biggest multi-lobulated cyst measured 21.6 × 33.6 × 41.7 mm in diameter (black arrow).

Hepatic abscesses are uncommon in dogs (2,4). These abscesses are characterized by the number of lesions, their location, and causative agents. In dogs, the majority of abscesses are located in the left liver lobe, whereas the right liver lobes are the most common sites of hepatic abscesses in human (1,6,11). Predisposing causes include alterations in blood flow, trauma, ascending biliary infections, liver lobe torsion, immunosuppression, and neoplasia, but the most common etiologic agents and routes are considered pyogenic bacteria throughout the biliary tract or hematogenous infection (3,5,8,9,10). The primary cause and exact route of the hepatic abscesses were not identified in this case, but they could be throughout the blood stream based on no history of trauma or underlying diseases such as immunosuppressants or neoplasia. In addition, on the CT scan, the splenic parenchymal showed heterogeneous contrast enhancement. During the surgical procedure, the anesthetic state of the patient was not stable. Therefore, we could not perform a splenectomy or obtained sample of the spleen. However, we suspected that the spleen, as well as the liver, was infected.

Recently, percutaneous drainage and alcoholization have been considered effective and minimally invasive methods for hepatic abscesses in veterinary medicine (9,11,12). However, surgical treatment may be performed in the presence of other problems (4,11). In this case, the patient was suspected to have peritonitis due to the rupture of the largest cyst and spleen infection on diagnostic imaging tests. Therefore, we performed a surgical resection, instead of providing percutaneous procedure.

In dogs, approximately 50% of infections are polymicrobial, and Escherichia coli, Staphylococcus spp., and Enterococcus spp. are the most commonly isolated agents. Anaerobic cultures are usually negative (5,11,12). Similar to the results of previous studies, the culture from our patient yielded multiple organisms with E. coli and Enterococcus spp. without anaerobic agents. After surgery, based on the guidelines for infectious hepatopathies in dogs (8), we prescribed broad-spectrum antibiotics for common enteric isolates, as the culture results were pending. In our case, E. coli showed sensitivity to several antibiotics including the drug that we used already, but Enterococcus faecium showed resistance or inadequate sensitivity to almost all antibiotics including meropenem. Both infectious agents were sensitive to doxycycline. However, at that time, doxycycline was not supplied to our country due to COVID-19.

Despite surgical interventions and treatment with several broad-spectrum antibiotics, the patient did not recover. We thought that these poor results were due to infection with multi-drug resistant bacteria and failure to provide more rapid diagnosis and aggressive treatment. In this case, hepatic abscess due to bacterial infection was diagnosed 4 days after the patient was brought to our hospital. However, the patient showed clinical signs 10 days before visiting our hospital. In dogs with hepatic abscesses, the clinical signs are often non-specific, and the diagnostic images may be inconclusive. If treatment is not initiated quickly, the infection can progress systemically. Thus, early detection of hepatic abscesses may contribute to more favorable results. If a hepatic abscess is suspected, an aggressive diagnostic approach including cystocentesis and CT scan is necessary.

Hepatic abscesses are rare condition in dogs but, diagnosis of this condition is difficult because of non-specific clinical signs and variety features of diagnostic tests. For favorable results in such patients, the clinician should conduct aggressive diagnostic procedures and treatments.

The authors have no conflicting interests.