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BackgroundThere is limited information on the epidemiology of canine mammary tumours. This study aimed to estimate the incidence and risk factors for mammary tumours in UK bitches.MethodsA nested case–control study was conducted within VetCompass to estimate the frequency and risk factors for clinically diagnosed mammary tumours during 2016 (VetCompass study). A second case–control study explored further breed associations for cases confirmed histopathologically compared to the VetCompass controls (laboratory study). Multivariable logistic regression was used to evaluate associations between risk factors and mammary tumours.ResultsThe incidence of mammary tumours was 1340.7/100,000 per year (95% confidence interval: 1198.1–1483.3). A total of 222 clinical cases (VetCompass study) and 915 laboratory cases (laboratory study) were compared to 1515 VetCompass controls in the two analyses. In the VetCompass study, Springer and Cocker Spaniels, Boxers, Staffordshire Bull Terriers and Lhasa Apsos had increased odds of developing mammary tumours. Neutering was associated with reduced odds, while odds increased with increasing age and a history of pseudopregnancy. In the laboratory study, increasing age was associated with greater odds of mammary tumours, and the breeds most at risk were similar to those identified in the VetCompass study.LimitationsThe timing of neutering was not consistently available. Comparing laboratory cases to VetCompass controls provided only exploratory evidence for the breed associations identified.ConclusionsThe study provides an update on the frequency of canine mammary tumours.

Chronic hepatitis C virus (HCV) infection reduces immune function through exhaustion and repertoire reduction. Sofosbuvir-based direct-acting antiviral (DAA) therapies offer >90% sustained virologic response (SVR) for HCV infection, but the extent of immune recovery and relationship with clinical factors are unknown. The longitudinal Alaska Hepatitis C Cohort provides an opportunity to evaluate immune recovery following sofosbuvir-based DAA and determine the influence of an extensive clinical and laboratory history. Forty-two persons (genotype 1; mean age 50 ± 12 years; 69% female) received 8 or 12-week sofosbuvir-based DAA therapy. Mean HCV RNA detection date was 2007 (range: 1994–2017). Pre-treatment HCV RNA levels averaged 4.9×106 IU/L (range: 4.9×104–2.4×107), were not detectable in any person after 4-weeks of therapy, and all achieved SVR. 18% (n=7) of persons had a fibrosis score of ≥F2 (moderate fibrosis to cirrhosis). Peripheral blood mononuclear cells (PBMCs) were evaluated at four time points: Pre-treatment (Pre), 4-weeks treatment (4wk), End of Treatment (EOT), and SVR post 12-weeks EOT (SVR-12) by flow cytometry to evaluate memory, exhaustion, and functional immune markers. Initial analysis revealed a significant increase in the CD4:CD8 from 4wk to EOT (p=0.007). Regulatory T-cells significantly increased at EOT and SVR-12 compared to 4wk (p=0.04 and 0.03, respectively). TIGIT showed a significant increasing trend in T-cells and NK cells throughout sampling timeline. Preliminary analysis indicates sofosbuvir-based DAA supports immune recovery to some extent. Additional analysis of immune recovery markers, determination of estimated date of HCV infection, and correlation of morbidity factors continues.