An exploration of potential under-recognised infectious causes of disease in dogs in Ireland

The aim of this study was to explore potential under-recognised infectious diseases in dogs in Ireland. The seroprevalence of selected vector-borne diseases (Borrelia burgdorferi, Anaplasma spp., Ehrlichia spp. and Dirofilaria. immitis) was evaluated by means of a cross sectional study including 500 dogs attending veterinary clinics for evaluation of different systemic diseases by means of a point of care enzyme-linked immunosorbent (ELISA) assay test. The included dogs were from all different Irish counties. Subsequently, a subset of 89 samples was submitted for molecular detection of Anaplasma spp., Ehrlichia spp., Babesia sp., Bartonella spp., haemotropic mycoplasmas, Wolbachia sp. and Rickettsia spp, and for detection of antibodies against Rickettsia spp. Dogs within this subset were selected aiming to ensure inclusion of all Irish counties, and preferentially including dogs with perceived higher likelihood of positivity based on final diagnosis, habitat, lifestyle, prophylactic ectoparasite therapy and clinical signs. All ELISA tests were negative other than a single positive result for D. immitis in a dog imported from Spain. Positive PCR results for a single infectious agent were obtained in four dogs and identified as E. canis, Bartonella henselae, M. haemocanis and M. haematoparvum. Exposure to Rickettsia spp. was documented in six cases: low titres in five dogs that had not travelled outside of Ireland and a high titre in the dog imported from Spain with dirofilariasis. Greyhound meningoencephalitis is a unique form of breed-restricted meningoencephalitis. Despite extensive exploration, a definitive cause has not been determined. Previous transcriptomic analysis has identified upregulated genes common to viral infection and autoimmunity pathways. A proteomic analysis of brain and cerebrospinal fluid samples from 7 affected and 7 control greyhounds was performed using mass spectrometry. Affected and control samples formed two distinct clusters on Principal Component Analysis (PCA). In total, 592 statistically significant differentially abundant (SSDA) proteins were identified in cerebral samples: 346 and 246 proteins with increased and decreased abundances, respectively. Fifty-one SSDA proteins were identified in cerebrospinal fluid samples. Proteins with the most differentially increased abundance included many associated with immunity such as interferon-induced GTP-binding protein Mx1, ISG15 ubiquitin-like modifier, two MHC class I DLA proteins, beta-2-microglobulin and integrin beta. The top upregulated proteins are known to be responsive to interferon production further suggesting a potential response to virus infection. Further exploration of potential viral causes of greyhound meningoencephalitis, and potentially other forms of meningoencephalitis of unknown origin in dogs, is warranted.