Renal Amyloidosis in Cattle: An Abattoir-Based Pathological Study in Urmia, Iran

Serum-associated amyloidosis is the most common form of amyloidosis in domestic animals and can lead to death. In this study, 1294 cattle (with a total of 2588 kidneys inspected) were inspected at the Sahand Abattoir, Urmia, Iran, over one year. Of these, 2462 kidneys were healthy (95.1%) while 126 kidneys had lesions (4.9%). There was no significant correlation between the frequency of gross lesions in the kidney and the sex or breed of the cattle (p>0.05). Additionally, the frequency of macroscopic changes in all cattle aged 4.5 years and older was significantly higher than that of younger ones and calves (p<0.05). Microscopic examination using hematoxylin and eosin, periodic acid schiff, and congo red tissue staining methods revealed the relative frequency of kidney lesions as follows: hemorrhage (27%), hydropic degeneration (16.7%), congestion (15.9%), interstitial nephritis (8.7%), glomerulonephritis (7.1%), acute tubular necrosis (6.3%), hydronephrosis (4.8%), cysts (4%), fibrosis (3.2%), amyloidosis (1.6%), pyelitis (1.6%), and renal lipidosis (0.8%). In two kidneys with amyloid deposits, one belonged to a bull with localized pulmonary tuberculosis, while the other belonged to a different bull with no other lesions detected in any organs. The most involved structures were glomeruli (98%), and only 2% of cortical tubules had amyloid deposits. Although renal amyloidosis is rare in slaughtered cattle in Urmia city, its heat resistance and potential transmission through food, especially to individuals with chronic inflammatory diseases, require careful inspection in slaughterhouses and condemnation of suspicious carcasses.