Fucosidosis in a family of American-bred English Springer Spaniels.

Fucosidosis was detected in a family of English Springer Spaniels in the United States. To our knowledge, these are the first reported cases of this disease in American-bred dogs. Affected and carrier status of dogs were determined by measuring the activity of the enzyme alpha-L-fucosidase in plasma and in leukocytes. Fucosidosis results in neurologic signs, particularly changes in behavior, in adolescent and adult dogs. Late onset of signs may result in misdiagnosis as a primary behavior problem or acquired neurologic disease. Fucosidosis is inherited in an autosomal recessive manner, and carrier dogs are clinically normal. Thus, the abnormal gene can become widespread in a population before homozygous-affected dogs are produced.