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identified as well. Chronic renal injury can also lead to uremic gastropathy which sonographically appears as hyperechoic mucosal borders. Cryptococcus and feline infectious peritonitis can both lead to chronic renal injury and the sonographic findings are variable.
Renal neoplasia in the cat is often due to lymphoma which can appear a nodules or diffuse cortical echogenicity and enlargement. Specific to cats is a hypoechoic halo around the kidney that can be present with lymphoma, but also with renal infection such as with FIP.
Bladder: Suspended echoes that do not cause acoustic shadowing, reverberation, or twinkle artifact distal to
the echo may be due to urine lipid. Clumping of these echoes may be present. Hyperbilirubinemic animals can have similar findings as can those with hematuria. Cystic calculi are hyperechoic and dependent and shadowing, not suspended. Cats may have accumulations of fine crystals that collect and shadow but when agitated break apart and look like a snow globe. Chronic cystitis can affect the cranioventral wall which becomes focally thickened with an irregular mucosa. Cats will develop
a hyperechoic and sometimes shadowing border
facing the lumen due to mucosal necrosis gas bubble entrapment, much like an ulcer. Pedunculated and broad- based masses can develop and can be benign polyps as well as malignant neoplasms. Pancreas
Chronic pancreatitis is poorly described in cats. The pancreas may be of normal size or enlarged with a heterogenous appearance. Hyperechoic foci with acoustic shadowing may represent mineralizations. Multiple hypoechoic round foci of a few millimeters in diameter may also be recognized. These may represent nodular hyperplasia or dilated pancreatic ducts.
Cavities of the pancreas cats are typically either due to abscesses or pseudocysts and appear as anechoic or hypoechoic cavities, possibly with a thickened wall. A number of investigators have attempted to assess the sensitivity and specificity of ultrasound compared to other imaging modalities for diagnosing pancreatitis in cats, however, with greatly varying results. Ultrasound will most likely remain one of the most important diagnostic tools in both dogs and cats as it allows not only assessment of the pancreas, but also that of other organs that may be involved in the inflammatory process.
Identifying important landmarks is critical to localizing
the pancreatic limbs as the pancreatic parenchyma can be difficult to differentiate initially from the surrounding mesentery. It may have indistinct margins and be isoechoic with the mesentery in the normal situation. The left lobe of the pancreas and body are easier to see than the right. Pancreatic ducts are easy to see in most cats. Also, the major duodenal papilla is the common entrance of the pancreatic and common bile duct in cats. The main landmark for identifying the left lobe and body in the cat is the portal vein. The pancreatic body lies directly ventral
to the portal vein caudal to the stomach. The left lobe
is caudal to the stomach and cranial to the transverse colon on the left side of the portal vein. It may continue caudally for a small distance to the level of the splenic hilus. The pancreatic duct is more commonly identified in cats and is seen as a small anechoic tubular structure in the body and left pancreatic lobe. The right lobe of the pancreas is small in the cat and is more difficult to identify. It is adjacent to the duodenum and follows it caudally. A small pancreatic duct can also be identified in it. The major duodenal papilla appears as a small nodule attached to the duodenal wall close to the cranial flexure.
The following are parameters that should be assessed when examining the feline pancreas:
The left and right limbs as well as the body should be examined and measured for thickness in the sagittal plane. Normal: Body: 0.5-0.9cm thick, Left lobe: 0.4=10cm thick, right lobe: 0.3-0.6cm. In acute disease, the pancreas may become enlarged as in dogs. However, this finding
is much more inconsistent in cats. In chronic disease the pancreas may be of normal size or smaller. Unremarkable changes do not rule out pancreatitis in cats. Pancreatic size does not increase with increasing age.
Echogenicity: Normal: iso- to hypoechoic with the mesentery. Abnormal: The pancreas usually becomes hypoechoic in acute disease. In chronic disease the pancreas may have a normal, hypo or hyperechoic appearance. Pancreatic echogenicity does not change with increasing age.
Abnormal Echotexture: Often the pancreas appears heterogeneous. It can become nodular with irregular borders. Nodular hyperplasia has the appearance
of small hypoechoic distinct nodules throughout the parenchyma. It is commonly seen in older cats. Nodules may be up to 1cm in diameter and the pancreas may be enlarged.
Pancreatic duct size: Normal:0.5-2.5mm diameter. Too little is known about the size of the duct in disease. However, there is a slight increase in size of the duct in older cats.Adrenal glands
Normal feline adrenal glands are 1cm in length, 3.7- 4.9mm pole height, have an ovoid shape and are hypoechoic and can have mineralizations in older animals. Cats with hyperthyroidism may have 20% larger glands, which can be explained by the stimulation of the hypothalamic-pituitary-adrenocortical axis by hyperthyroidism. Treated hyperthyroid cats had a length of 1.1cm and up to a 4.9mm pole height. Untreated hyperthyroid cats can have a gland length of 1.5 cm
and pole height of up to 4.9mm. Adrenal tumors most always lead to much greater size changes, rather in the centimeter rather than mm range. Adrenal tumors in cats with hyperaldosteronism are typically 2-4cm in size. Cats with acromegaly can have bilateral enlargement also.
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