Path. vet. 4: 120-136 (1967)

From the Department of Pathology, The University of Bristol, England

Renal Calcification in the Domestic Cat A Morphological and X-Ray Diffraction Study

VANDAM. LUCKEand A. C. HUNT

The reports in the literature on spontaneous renal calcification in the cat are few and conflicting. BLOOMSdescribed calcification in the kidneys of dogs, and stated that it was a common finding in that species, but was rare in cats. BAUMANN~ described calcification in the kidneys of the dog and cat under the heading of “fatty calcareous infarcts” and considered it to be a common finding in both species. JUBB and K E N N E D Y stated ~ ~ that dystrophic calcification is common in the dog, but very unusual in other species. We have found calcification in the renal medulla in both diseased and in otherwise normal kidneys of many domestic cats.

Material and Methods The findings in this study are based on examination of kidneys from 104 cats with spontaneous renal disease and the kidneys of 33 healthy cats, which had no renal lesion except for tubular calcification. All the cats were obtained from veterinary practices in Bristol. A complete post-mortem examination was made on all cats and representative tissues from pancreas, stomach, intestine, lung, aorta (thoracic and abdominal), heart, vertebrae TS-Ts, femur, liver, thyroid and parathyroid were fixed in buffered neutral 10% formalin. At least 4 blocks of tissue were examined from each half of each kidney. All paraffin sections were stained with Weigert’s haematoxylin and eosin. Other stains used included periodic acid-Schiff (PAS), Mallory’s blue trichrome, VerhoefYs ehstic van Gieson, azure A, Alcian blue,

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alizarin red, von Kossa’s method and combined PAS and von Kossa’s method. Von Kossa’s method depends on the presence of phosphate and carbonate and as insoluble phosphates and carbonates in animal tissue are nearly always those of calcium, the method is normally regarded as sufficiently specific for this element. The formation of an orange-red lake with alizarin red is generally considered to be a good indication that a mineral is a calcium salt. All the mineral that we have demonstrated in this study stains positively by both methods. Frozen sections were stained with oil red 0 and haematoxylin, Nile blue sulphate, and Sudan black. They were also examined by polarised light and by the Schultz reaction for cholesterol and its esters and the method after F E I G I Nfor ~ ~differentiation of cholesterol from its esters. Portions of calcified renal medulla for X-ray diffraction were dissected from the fresh kidneys, vacuum dried and stored in sealed ampoules. Pieces of the dried calcified material were cut and mounted in a tube (1-2 mm diameter) made by casting several layers of Durofix glue around a fine copper wire. The tube was mounted in the specimen holder at the centre of a Phillips PW 1024 114.3 mm diameter powder camera with narrow collometers. The X-ray machine was a Phillips 11704 with Cu I< radiation filtered with a nickel foil to remove the I