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)

Abstract

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 4 months, if possible, or more frequently in case of illness. Cats that died during study were necropsied. Health status of live cats was checked 5 years 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.

Serum paraoxonase 1 activity in cats: analytical validation, reference intervals, and correlation with serum amyloid A and alpha-1-acid glycoprotein

“…Similarly, results of PON1 activity recorded in specimens with normal and high SAA, using the cutoff of 26.7 mg/L defined in a previous study, were compared. 24,42 Finally, the PON1 activity of cats with normal (< 26.7 mg/L), medium (26.7–135.0 mg/L), or very high SAA (> 135.0 mg/L, ~ 5-fold the cutoff) were compared.…”

“…Feline AGP was measured using a single radial immunodiffusion (SRID) kit (Tridelta Development) as described previously. 42 Feline SAA was measured using a human immunoturbidimetric assay (LZ test SAA; Eiken Chemical), validated previously in cats, 24 on an automated spectrophotometer (ILAB 300 Plus; Instrumentation Laboratory).…”

Multi-omic analyses in Abyssinian cats with primary renal amyloid deposits

“…The proteomic analysis identified three different isoforms of the SAA protein, two of which corresponding to partial sequences, according to the databank. The presence of abundant wild type AA in the deposits but not constant high SAA concentration, as experienced in the practice and reported in a longitudinal story on affected Abyssinians 67 , has suggestive similarities both with the suggested mechanism of rapid incorporation of wild type AA into the deposits drastically reducing the circulating SAA concentration, recorded in a mouse model 68 and with the unresolved issue of a short seeding and nucleation that could make unnecessary chronic high SAA concentrations for docking and misfolding in the tissues 69 .…”

Hepatic AA amyloidosis in a cat: cytologic and histologic identification of AA amyloid in macrophages

“…Familial amyloidosis, commonly seen in Siamese and Abyssinian cats, has also been reported in DSH and Oriental cats; however, the family history was not available in this case to investigate this possibility. In addition, the possible increase in inflammatory cytokines inducing familial amyloidosis in Abyssinian cats is debated . Another potential explanation for this cat's amyloidosis given the low measured SAA concentration might be the production of an atypical SAA which is not reacting with the validated testing antibodies.…”