Sandy Weltan
Serum amyloid A is a major acute phase protein in many species. We have upgraded to a veterinary specific test (Vet-SAA) which is adapted to react to SAA in multi-species, including horses, dogs, cats, ruminants and rabbits. The reporting units have also changed from ug/mL to mg/L to comply with WHO International Standard NBSc code: 92/680.
SAA is useful for detecting and monitoring inflammation, due to its rapid response and marked increase (10x or more) above the normal reference interval. Because of the non-specificity of an acute phase protein (APP) response, a clinical decision limit is more useful. The interpretation of results for the new test is different from those reported previously and will be provided for each test result.
Horses: The clinical decision limit suggested for VET-SAA in horses is >30 mg/L. The peak is usually at 36-48 hrs. The average concentration with non-inflammatory disease is 45.1 mg/L. Horses with inflammatory disease generally have a marked increase in amyloid A levels (>250 mg/L).
Cats: The clinical decision limit suggested for VET-SAA in cats is >20 mg/L. Interestingly, a small percentage of hyperthyroid cats have VET-SAA concentrations close to this cut-off. The most likely explanation is that those cats have concurrent inflammatory disease. SAA was shown in a previous study to have low sensitivity for some diseases, notably immune mediated anaemia but that was using the previous LZ-SAA and sample numbers were low.
Dogs: CRP has been the APP of choice in dogs for a long time. SAA is also a major acute phase protein in dogs and the VET-SAA has been shown to give comparative results SAA peaks later than CRP (3 and 1 day, respectively) and decreases later (7 and 3 days, respectively). The clinical decision limit suggested for VET-SAA in dogs is 63.8 mg/L.
References:
· Behling-Kelly E et al. Acute phase protein response and changes in lipoprotein particle size in dogs with systemic inflammatory response syndrome. J Vet Intern Med. 36:993-1004, 2022.
· Bulgarelli et al. Apolipoprotein A1 and serum amyloid A in dogs with sepsis and septic shock. Front Vet Sci. 10:1098322, 2023.
· Jacobsen S et al. Validation of an equine serum amyloid A assay with an unusually broad working range. BMC Vet Res.15:462, 2019.
· Lofqvist K et al. Usefulness of C-reactive protein and serum amyloid A in early detection of postoperative infectious complications to tibial plateau levelling osteotomy in dogs. Acta Vet Scand. 60:30, 2018.
· Tamamoto T et al. Verification of Measurement of the Feline Serum Amyloid A (SAA) Concentration by Human SAA Turbidimetric Immunoassay and Its Clinical Application. J Vet Med Sci. 70:1247-1252, 2008.
· Waugh EM et al. Validation of an automated immunoturbidimetric assay for feline serum amyloid A. BMC Vet Res.18:359, 2022.