Is there a correlation between canine adult-onset demodicosis and other diseases?

Demodicosis is frequently seen in small animal practice. In older dogs, it is often associated with immunosuppression and immunosuppressive diseases. The aim of this study was to evaluate a larger number of dogs with adult-onset demodicosis (AOD) at the veterinary teaching hospitals of the University of Sydney/Australia and the University of Munich/Germany. Breed predispositions were compared with the two control populations. Of more than 20 000 dogs and 15 000 in each respective hospital population, 54 dogs in Munich and 68 dogs in Sydney were diagnosed with AOD at a mean age of 8 years. Breed predispositions were seen for West Highland White Terriers in Munich (p<0.0001) and Maltese Terriers and Shih Tzus in Sydney (p<0.01). Concurrent diseases were confirmed in approximately 40% of the dogs both in Munich and Sydney. A significant association was only found between AOD and hyperglucocorticoidism, hypothyroidism and (in Munich) leishmaniosis. Neoplastic diseases were not significantly more common in dogs with demodicosis than in the total population at both locations (p>0.05). Consequently, dogs with AOD should be evaluated for concurrent hyperglucocorticoidism and hypothyroidism, and, in areas of the world where this is prevalent, also for leishmaniosis.