Steroid responsive meningitis-arteritis (SRMA) is a well-recognised inflammatory syndrome of the dog, the diagnosis of which remains unsatisfactory based on current clinical criteria and non-specific laboratory investigations. The aim of this study is to report the value of acute phase proteins (APP) and IgA in the diagnosis and management of SRMA.

APPs have become an important tool in diagnosing, managing and prognosticating inflammatory diseases in humans and are developing a similar utility in domestic species. Our laboratory has previously demonstrated that C-reactive protein (CRP), serum amyloid A (SAA), haptoglobin (Hp) and alpha-1-acid glycoprotein (AGP) are significantly elevated at initial presentation of SRMA and that the remission of clinical signs, induced by immunosuppressive therapy, reduces but does not eliminate this increase in serum concentrations. Raised serum IgA has been described as a feature of SRMA.

A prospective study recruited ten dogs with a clinical diagnosis of SRMA, and no history of prior steroid administration, presenting to the University of Glasgow Small Animal Hospital between May 2006 and May 2007. Dogs were treated with a standard protocol for SRMA using immunosuppressive doses of prednisolone. Serum samples were collected from all dogs at initial investigation, two weeks into treatment (when all dogs were in remission) and disease resolution (four weeks after treatment).

CRP, SAA, Hp and AGP concentrations were measured using immunoturbidimetry, ELISA, haemoglobin binding and radial immunodiffusion respectively. IgA concentration was measured using a commercial dog IgA ELISA quantitation kit (Bethyl Laboratories, USA).

Serum IgA concentrations were elevated above the reference range at diagnosis exhibiting a trend of increasing between diagnosis and remission (9/10) (p=0.2406) and reducing, but not normalising, at resolution (10/10) (p=0.0615). Conversely CRP, SAA and AGP were significantly increased at presentation compared to remission and resolution (p<0.001), with Hp increasing slightly during treatment due to steroid induction (p=0.0524).

Serum APP concentration correlates with the clinical course of SRMA with resolution of clinical signs corresponding to a decrease in concentration. Conversely, IgA appears to increase initially suggesting different aspects of the disease process are reflected by these different classes of peripheral markers. In conclusion APPs would appear to offer greater clinical utility in the management of SRMA, particularly in the recognition of remission and resolution, whilst serum IgA concentration may provide support to the initial diagnosis, though the reason for the elevation of this immunoglobulin in SRMA is unknown.