Appendix A.

Definitions of normal imaging findings for canine abdominal ultrasound.

Organ system	Normal description	Reference
Peritoneal space	The peritoneal space was evaluated for increased fluid or gas volume, as well as any identifiable masses or change in echogenicity.	(23)
Lymph nodes	Lymph centers examined included, but were not limited to the jejunal, hepatic, splenic, colic, mesenteric, gastroduodenal, medial iliacs, and sublumbar lymph nodes. The lymph nodes were relatively isoechoic to surrounding normal soft tissues with regular margins. Normal lymph nodes had a short axis diameter to long axis diameter of < 0.4 cm.	(24,25)
Pancreas	Pancreatic tissue margins were indistinct, and the echogenicity was isoechoic to slightly hypoechoic to that of surrounding mesenteric fat with thickness < 1 cm.	(26)
Adrenal glands	Adrenal glands were hypoechoic to the surrounding fat. Identification of a corticomedullary rim was considered insignificant if appropriately sized. On longitudinal view, the normal glands appeared bilobed to oblong with a maximum width less than 0.81 cm for the right adrenal gland and 0.74 cm for the left adrenal gland.	(27,28)
Liver	Hepatic parenchyma was uniformly hyperechoic/isoechoic to right renal cortex and hypoechoic to spleen with more course echotexture. The caudal margin of the hepatic parenchyma was cranial to the stomach with a sharp angle.	(29)
Gallbladder and biliary tract	Gallbladder wall was a thin echogenic line between anechoic bile (in the normal patient) and the hepatic parenchyma. The gallbladder tapered into the cystic duct. The common bile duct was < 0.3 cm. Dependent echogenic luminal material in the gallbladder was interpreted as sludge and considered insignificant.	(30)
Spleen	Normal splenic architecture was homogeneous with fine echotexture that was hyperechoic the left renal cortex and liver.	(31)
Gastrointestinal tract	The GI tract was evaluated for wall thickness, appearance of wall layers, luminal contents and diameter, and motility. Wall thickness was measured from the inner luminal interface to the outer serosal surface, and considered normal if within published reference ranges (stomach: 2 to 5 mm, duodenum: 3 to 6 mm depending on body weight, jejunum: 2 to 5 mm depending on body weight, ileum: 2 to 4 mm, and colon: 2 to 3 mm). Wall layers were considered normal if all layers were clearly visible, had normal relationship with each other, and were of normal echogenicity.	(32,33)
Urinary tract	The kidneys had a distinction between the cortex and medulla with a normal shape. Size was fairly subjective and if felt abnormal then a renal length to aorta ratio was calculated; abnormal was considered < 5.5 or > 9.1. The ureters were indistinct with acute tapering at the renal hilus. No luminal hypoechogenicity within the ureter. The renal pelves were < 2 mm on transverse image. The bladder was evaluated for content, wall layer appearance, and wall thickness according to published reference ranges depending upon bladder distention (minimally distended ~2.3 mm, moderately distended ~1.4 mm) and body weight.	(34–36)
Genitals	If present, ovaries/uterus or the testes were identified. The ovaries were hypoechoic to region peri-renal fat with homogeneous appearance with similar echogenicity to the renal cortex. Uterine horns and body did not have luminal fluid. The testes were located within the scrotum with symmetry and a distinct hyperechoic mediastinum that dissects through homogeneous parenchyma.	(37,38)