Changes in Serum and Urine SAA Concentrations and Qualitative and Quantitative Proteinuria in Abyssinian Cats with Familial Amyloidosis: A Five-year Longitudinal Study (2009-2014)

BackgroundDiagnosis of familial amyloidosis (FA) in Abyssinian cats usually is made on postmortem examination. Hypothesis/ObjectivesSequential analysis of serum SAA (sSAA), urinary SAA (uSAA), urinary protein:creatinine (UPC) ratio, or sodium-dodecylsulfate agarose gel electrophoresis (SDS-AGE) may facilitate early identification of cats with FA. AnimalsTwenty-three Abyssinian cats belonging to cattery A or B (low and high prevalence of FA, respectively). MethodsProspective longitudinal study using 109 blood and 100 urine samples collected over 4-year period every 4months, if possible, or more frequently in case of illness. Cats that died during study were necropsied. Health status of live cats was checked 5years after enrollment. Serum amyloid A (sSAA) and urinary SAA (uSAA) were measured using ELISA kit. The UPC ratio and SDS-AGE also was performed. ResultsFamilial amyloidosis was not identified in cattery A, whereas 7/14 cats from cattery B had FA. Serum amyloid A concentrations were not significantly different between cats in catteries A and B or between cats with or without FA, despite frequent peaks in cats from cattery B. Conversely, uSAA was significantly higher in cattery B, especially in the terminal phases of FA. Proteinuria occasionally was found in cats from both catteries, especially in those with FA. Urine protein electrophoresis identified mixed proteinuria only in cats with FA. Conclusions and Clinical ImportanceSerum amyloid A and UPC ratio are not helpful for early identification of Abyssinian cats with FA. Conversely, increases in uSAA with or without mixed proteinuria may be found before onset of clinical signs in cats with FA.