Prospective ultrasonographic phenotyping and infectious polymerase chain reaction screening of canine hepatobiliary disease in southern Vietnam.

Background and Aim: Canine hepatobiliary disorders are frequently encountered in small animal practice; however, prospective clinic-based studies integrating ultrasonographic phenotyping with infectious molecular screening remain limited in tropical Southeast Asia. This study aimed to determine the frequency of ultrasonographically detected hepatobiliary abnormalities, identify associated host factors, characterize ultrasonographic phenotypes, and assess infectious etiologies in dogs with suspected hepatobiliary disease in southern Vietnam. Materials and Methods: A prospective observational study was conducted at the Veterinary Teaching Clinic, Can Tho University, Vietnam, between January and November 2025. Among 1,278 canine presentations, 111 dogs meeting predefined clinical and clinicopathologic criteria underwent abdominal ultrasonography, and 63 dogs with confirmed hepatobiliary abnormalities were enrolled. Hematologic and serum biochemical analyses were performed in all enrolled dogs. Cases classified with a hepatitis ultrasonographic phenotype underwent conventional polymerase chain reaction (PCR) screening of ethylenediaminetetraacetic acid (EDTA)- anticoagulated blood samples targeting vector-borne pathogens, Results: Hepatobiliary abnormalities were identified in 63/1,278 dogs (4.93%) and in 63/111 clinically suspected dogs (56.76%). Ultrasonographic positivity was significantly associated with exotic breed (odds ratio [OR] = 2.29), age >8 years (OR = 13.93), obesity (OR = 4.78), and underweight body condition (OR = 3.38). Hepatitis was the predominant ultrasonographic phenotype (57.14%), followed by hepatic lipidosis (30.16%) and cirrhosis (12.70%). Dogs with hepatitis commonly exhibited anorexia, vomiting, diffuse hepatic hypoechogenicity, hepatomegaly, and gallbladder abnormalities. PCR screening detected infectious agents in 55.56% of hepatitis cases, including vector-borne pathogens (41.67%), Conclusion: Ultrasonography effectively identified distinct hepatobiliary imaging phenotypes in dogs and provided a practical diagnostic framework for referral-based clinical settings in resource-limited regions. Integration of ultrasonography with clinicopathologic evaluation and targeted PCR screening enhanced preliminary etiologic assessment, particularly in dogs with inflammatory hepatopathies. Older age and abnormal body condition were important host-associated factors linked with ultrasonographic positivity. Although imaging-based classification may assist clinical triage, histopathological confirmation remains necessary for definitive diagnosis.