Feline Medicine Q&A 22

This question was provided by Manson Publishing as part of the OVAL Project. See more Feline Medicine questions

The picture shows a kidney removed from a cat at post mortem.

Question	Answer		Article
Comment on the size of this kidney and how renal size is normally assessed antemortem.	The kidney pictured is close to 60 mm in length and thus clearly enlarged. Renal size can be determined subjectively by abdominal palpation, but is better determined by radiography or ultrasonography. On a VD radiograph, the normal renal size varies between 2.0 and 3.0 times the length of L2. Ultrasonographically, normal renal size in cats varies between 30 and 44 mm.		Link to Article
Is speculation on the diagnosis possible from the gross appearance in this case?	The kidney pictured is grossly enlarged and multiple pale lesions varying in size from approximately 1–4 mm in diameter are visible on the serosal surface. The lesions are slightly raised giving an uneven surface to the kidney. The lesions suggest a multifocal infiltrative or inflammatory disease. Major differential diagnoses would be lymphoma, FIP, and mycobacterial infection. In this case histology confirmed the diagnosis of FIP.		Link to Article
In general, what are the indications and precautions for renal biopsy?	A fine needle aspirate is usually sufficient to diagnose lymphoma; renal biopsy is indicated to confirm suspected FIP or other focal infiltrative/inflammatory diseases. Renal biopsy (for histology and culture) can also be valuable in investigation of significant proteinuria and in other cases of renal disease where the results could lead to significantly improved therapy (e.g. pyelonephritis). Renal biopsy should only be performed after careful patient evaluation and assessment of the risk:benefit ratio. A coagulation profile is essential prior to renal biopsy. Ultrasound-guided or surgical needle biopsy, ensuring that the needle stays within the renal cortex, is likely to be the safest method.		Link to Article