Risk factors and predictors of angiostrongylosis in naturally infected dogs in the southeast of England

Abstract

Canine pulmonary angiostrongylosis is a snail-borne parasitic infection caused by the nematode Angiostrongylus vasorum. The spread of A. vasorum across the UK in recent years, alongside the launch of new pharmaceutical products licenced for its treatment and prevention, has led to raised awareness of this parasite among veterinarians and the public alike. This raised profile has been beneficial in reducing canine morbidity and mortality associated with infection, especially in parts of the country where it had not previously been routinely diagnosed. It is vital, therefore, given raised public awareness and geographical spread of the parasite, that the veterinary professionals have demographic data to help give accurate risk-based advice. This study retrospectively evaluated demographic factors (age, gender and breed) and clinical presentation of 100 dogs with natural A. vasorum infection by reviewing the clinical record database at private practices, spanning the period from 2003 to 2009, alongside 100 dogs presenting for other reasons as a control sample. A significant relationship was detected between young age and A. vasorum infection (P<0.001), with dogs less than 1 year of age 4.2 times more likely to fall into the infected group. Gender was not identified as a significant risk factor for A. vasorum infection in dogs. Breed was a significant risk factor, with Cocker Spaniels over-represented in the infected group, and Staffordshire Bull Terriers and cross-breeds under-represented. The strongest contrast was between cross-bred and pure-bred dogs as a whole, with the latter 23 times more likely to present with angiostrongylosis. Significant associations were found between A. vasorum infection and dogs presenting with cough, coagulopathy, vomiting/diarrhoea and/or lethargy (P<0.05). The diagnostic value of clinical signs for the presence of disease, expressed by area under the receiver operating characteristic curve, was >0.7, indicating that correct diagnosis (discrimination between dogs with or without the disease) can be achieved in 70% of the clinical cases by accurate history taking. These findings provide important clues regarding the risk of infection to an individual dog, and thus may facilitate improved recognition of infection based on clinical presentation, and implementation of preventative strategies to combat A. vasorum infection.