Aim

To investigate the epidemiology of a recently emerging canine disorder of unknown aetiology that manifests as gastrointestinal signs in dogs soon after walking in particular woodland areas in late summer and autumn.

Method

Using a case control design, questionnaires were developed to cover four specific study areas where clinical cases resembling SCI had been initially noted in autumn 2009, and included two sites in Nottinghamshire and two sites in Norfolk. Questions were based on routine health and management of the dog, and management and behaviour of the dog during the visit to the study area. The population at risk was dogs walked in the study areas since the beginning of August 2010. Cases walked in the study area and became affected with two or more clinical signs from vomiting, diarrhoea, abdominal pain, fever, lethargy, anorexia, muscular tremors. Control dogs were walked in study areas but did not become ill. Multivariable logistic regression analyses were conducted with STATA software to examine associations between SCI and a wide range of variables.

Results

A total of 400 questionnaires were returned, 53 from cases and 347 from controls with 215 questionnaires (35 cases and 180 controls) coming from one Norfolk site. Data analysis indicated three potentially significant risk factors, although two only showed marginal statistical significance (0.05 < P < 0.1) in a multivariable model. Dogs were more than twice as likely to be a case if the owner lived more than 50 km from the study site (OR = 2.4, 95%CI 1.19–4.96%, P = 0.015). The more times per day a dog was walked in one of the study areas, the more likely it was to become a case (OR = 1.3, 95%CI = 0.98–1.85, P = 0.066) and there was decreased risk in dogs that picked up or ate sticks (OR = 0.4, 95%CI = 0.21–1.01, P = 0.054).

Conclusions and Potential Relevance

Although the specific aetiology of SCI remains unknown, the 2010 study provided insights into specific features of populations at risk and geographical sites worthy of further investigation. Site visits to one Norfolk site, conducted soon after cases recurred in September 2011 strongly suggested that blue-green algae, poisonous plants and fungi were unlikely causes of SCI. Investigations into alternative theories and pathogenic mechanisms for the disease are currently underway.

Figure 1. Temporal changes in occurrence of new cases between June and November 2010.