Comparison of serum amyloid A and C-reactive protein as diagnostic markers of systemic inflammation in dogs.

The diagnostic performance of canine serum amyloid A (SAA) was compared with that of C-reactive protein (CRP) in the detection of systemic inflammation in dogs. Sera from 500 dogs were retrospectively included in the study. C-reactive protein and SAA were measured using validated automated assays. The overlap performance, clinical decision limits, overall diagnostic performance, correlations, and agreement in the clinical classification between these 2 diagnostic markers were compared. Significantly higher concentrations of both proteins were detected in dogs with systemic inflammation (SAA range: 48.75 to > 2700 mg/L; CRP range: 0.4 to 907.4 mg/L) compared to dogs without systemic inflammation (SAA range: 1.06 to 56.4 mg/L; CRP range: 0.07 to 24.7 mg/L). Both proteins were shown to be sensitive and specific markers of systemic inflammation in dogs. Significant correlations and excellent diagnostic agreement were observed between the 2 markers. However, SAA showed a wider range of concentrations and a significantly superior overall diagnostic performance compared with CRP.

Comparaison de la protéine amyloïde sérique A et de la protéine C réactive comme marqueurs diagnostiques de l'inflammation systémique chez les chiens. La performance diagnostique de l'amyloïde sérique canine A (SAA) a été comparée à celle de la protéine C réactive (PCR) dans la détection de l'inflammation systémique chez les chiens. Le sérum de 500 chiens a été inclus rétrospectivement dans l'étude. La protéine C réactive et la SAA ont été mesurées en utilisant des bioanalyses automatisées validées. La performance de chevauchement, les limites de décision cliniques, la performance diagnostique globale, les corrélations et la concordance dans la classification clinique entre ces 2 marqueurs diagnostiques ont été comparés. Des concentrations significativement supérieures des deux protéines ont été détectées chez les chiens avec une inflammation systémique (plage de la SAA : de 48,75 à > 2700 mg/L; plage de la PCR : de 0,4 à 907,4 mg/L) comparativement aux chiens sans inflammation systémique (plage de la SAA : de 1,06 à 56,4 mg/L; plage de la PCR : de 0,07 à 24,7 mg/L). Il a été démontré que les deux protéines étaient sensibles et des marqueurs spécifiques de l'inflammation systémique chez les chiens. Des corrélations significatives et une concordance diagnostique excellente ont été observées entre les deux marqueurs. Cependant, la SAA a indiqué un écart plus vaste pour les concentrations et une performance diagnostique significativement supérieure comparativement à la PCR.(Traduit par Isabelle Vallières).

Canine serum amyloid A (SAA) measured by automated latex agglutination turbidimetry is useful for routine sensitive and specific detection of systemic inflammation in a general clinical setting.

Canine serum amyloid A (SAA) is a useful diagnostic marker of systemic inflammation. A latex agglutination turbidimetric immunoassay (LAT) was validated for automated measurements. The aim of the study was to evaluate the clinical applicability of SAA measured by the LAT. SAA was measured in 7 groups of dogs with and without systemic inflammation (n=247). Overlap performance was investigated. Diagnostic performance was compared to body temperature and leukocyte markers. Clinical decision limits for SAA were estimated. In dogs with neurological, neoplastic or gastrointestinal disorders (n=143), it was investigated whether a higher proportion of SAA positive dogs could be detected in cases of complications with risk of systemic inflammation. Significantly higher concentrations of SAA were measured in dogs with (range [48.75; 5,032 mg/l]), compared to dogs without systemic inflammation [0; 56.4 mg/l]. SAA was a more sensitive and specific marker of systemic inflammation (area under the receiver-operating characteristic curve (AUC) 1.00), compared to body temperature (0.6) and segmented neutrophils (best performing leukocyte marker, 0.84). A clinical decision limit of 56.4 mg/l was established giving close to perfect discrimination between dogs with and without systemic inflammation. Higher proportions of SAA-positive dogs were observed in dogs with neurological, neoplastic and gastrointestinal disorders with complications known to increase risk of systemic inflammation, compared to uncomplicated cases. The automated LAT makes SAA applicable as a relevant diagnostic marker of systemic inflammation in dogs for routine random-access real-time use in a general clinical setting.