ALS and pet exposure.

To examine animal exposure in ALS patients, a case-control study was undertaken on 40 ALS patients and 40 closely matched controls. Exposure to pets of any kind and to small dogs in the period from birth until 10 years before onset of ALS symptoms was significantly increased. Affected men showed a trend toward increased exposure to neurologically ill pets, but there was no significant difference when male and female cases were grouped. No differences between ALS cases and controls were observed in exposure to any other single animal species. There may be a link between ALS and exposure to house pets.