P. 565

S. Hecht1
1University of Tennessee, Small Animal Clinical Sciences, Knoxville, USA
Silke Hecht, Dr. med. vet., Diplomate ACVR, Diplomate ECVDI
Professor in Radiology
C247 Veterinary Medical Center, University of Tennessee College of Veterinary Medicine, Knoxville, TN 37996, USA
Vomiting is a common presenting complaint in cats
and may be caused by a variety of gastrointestinal and non-gastrointestinal disorders. Diagnostic imaging plays an important role in the work-up of the vomiting cat. While advanced imaging modalities (CT, MRI) are gaining popularity in the evaluation of the small animal abdomen, radiographs and ultrasound remain the imaging techniques of choice. Contrast procedures may also be indicated in certain cases.
Abdominal radiographs (1):
Routine abdominal radiographs should include right lateral and ventrodorsal views. Due to re-distribution
of gas and  uid with gravity an additional left lateral
view is helpful in the evaluation of pylorus and proximal duodenum and is strongly recommended in vomiting animals. Additionally, a horizontal beam view may be helpful in cases of suspected pneumoperitoneum. Evaluation of abdominal radiographs includes assessment of serosal detail (increased in cases of pneumoperitoneum; decreased in cases of abdominal effusion, visceral crowding and lack of intra-abdominal fat), extra-abdominal structures, and abdominal organs which are systematically evaluated using Roentgen signs (number, size, shape, opacity, margination, location). In normal cats the liver, spleen, kidneys, urinary bladder, and gastrointestinal tract are visible. Parenchymal organs are of homogenous soft tissue opacity. The liver is sharply marginated and contained within the costal arch. The spleen is only visible on the VD view as a small triangle caudal to the gastric fundus. The kidneys are bean shaped and fairly symmetric in size. On a VD view they measure 2.4 – 3.0x length of L2 (intact cats) and 1.9 – 2.5x length of L2 (spayed/neutered cats), respectively. The urinary bladder is variable in size.
The appearance of the gastrointestinal tract (GIT) is
variable. The stomach may contain ingesta, gas and/or a small amount of  uid. The small intestine usually contains a mixture of gas and  uid, and the colon contains gas and formed faecal material. Solid material should only
be present in the stomach and the colon. Gastric and intestinal wall thickness is dif cult to evaluate on survey radiographs due to luminal contents. Overall small intestinal diameter should not exceed 12 mm or 2x the height of L2. Especially in fat cats the extremity of the left lobe of the pancreas may be visible on the VD view. Adrenal glands may be visible if mineralized. The only reproductive organ seen is the uterus in pregnant cats which is of soft tissue opacity until mineralized foetal structures appear. Normal abdominal lymph nodes are not visible.
Abdominal ultrasound (2, 3):
The ultrasonographic examination complements abdominal radiographs. Ultrasound is inferior to radiographs e.g. in the assessment of liver size, in the detection of mineralized or metallic peritoneal foreign bodies, and in the detection of a small volume peritoneal or organ associated gas. Ultrasound is superior to radiographs e.g. in the assessment of internal organ structure and the detection of a small volume effusion. Also, ultrasound allows guided tissue sampling ( ne needle aspiration, biopsy) for further evaluation. With
the exception of critically ill/unstable patients the ultrasound examination of a vomiting cat should include evaluation of all abdominal organs. The normal liver is hypoechoic to the spleen and similar in echogenicity as adjacent falciform fat. The gall bladder is thin walled (< 1mm) and contains anechoic bile. The spleen is small (<1 cm in thickness) and relatively hyperechoic. The kidneys are smoothly marginated and have a distinct corticomedullary de nition. The renal pelvis is usually empty, although a renal pelvis diameter of 1-2mm may be normal secondary to diuresis or back pressure
from a distended urinary bladder. Normal ureters are not visible. The urinary bladder is thin walled and contains urine which may contain echogenic particles in suspension. The adrenal glands are more rounded than in dogs and measure less than 5mm in thickness. The stomach, duodenum, jejunum, ileum and colon can be distinguished based on differences in position, wall thickness, appearance of the wall layers, and contents. The gastric wall measures less than 4mm in thickness and has prominent submucosal and muscularis layers. Gastric contents are highly variable; however, normal cats usually have little to no  uid within the stomach. The duodenum and jejunum have distinct layers (thick inner mucosal layer; thin submucosa, muscularis, serosa) and measure up to 2.5mm in wall thickness. These intestinal segments typically contain a small amount of gas and
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