Starry Sky Hepatic Ultrasonographic Pattern in Horses: 18 Cases (1989-2010)

The starry sky hepatic ultrasonographic pattern was associated with hepatic granulomas. The pattern seemed to be unrelated to the primary disease process in most cases. Authors’ addresses: Department of Veterinary Clinical Medicine, College of Veterinary Medicine, University of Illinois, 2001 South Lincoln Avenue, Urbana, IL 61802 (Carlson); Department of Large Animal Clinical Sciences (Chaffin and Schmitz) and Department of Veterinary Pathobiology (Corapi and Snowden), College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, 4475 TAMU, College Station, TX 77843-4475; e-mail: [email protected].

1. Introduction

The starry sky pattern is an unusual and dramatic ultrasonographic appearance of the equine liver characterized by numerous small hyperechoic foci, some of which cast an acoustic shadow. The pattern is differentiated from hepatoliths, which are found within the biliary ducts rather than diffusely throughout the hepatic parenchyma. The objectives of this retrospective study were to describe the signalment, clinical signs, clinicopathological findings, primary disease processes, and ultrasonographic findings of horses that exhibited this pattern and to determine the gross and histological changes of the liver and possible etiologies associated with this pattern.

2. Materials and Methods

Ultrasonographic images and case records were reviewed for all horses that exhibited the starry sky pattern.

3. Results

The starry sky pattern was identified in 18 adult horses of mixed sex and breed. Weight loss and anorexia were the most common clinical signs. Liver size and echogenicity were normal in most horses. The hyperechoic foci frequently caused acoustic shadowing. Biliary dilation was uncommon. The pattern was the result of numerous hepatic granulomas in all cases evaluated histologically. Gamma-glutamyl transferase (GGT) was increased in fewer than one-half of the horses. Fifteen horses had an additional disease process that was the apparent primary cause of clinical signs. 

4. Discussion

Practitioners should recognize this dramatic ultrasonographic pattern and its association with hepatic granulomas. The etiology of the granulomas is unknown. The pattern seems to be associated with another primary disease process in most cases.