Hyperphosphatasemia in Scottish Terriers: 7 Cases

Abstract

Increased serum alkaline phosphatase (ALKP) activity in dogs is commonly encountered. In the study reported here, 7 Scottish Terriers were identified with hyperphosphatasemia, for which a cause could not be determined. The clinicopathologic findings of the syndrome are described and correlated with hepatic pathologic changes in biopsy specimens and in specimens obtained at postmortem examination. Five of the 7 dogs were related. The ALKP activity ranged from 1.7 to 17 times the reference value at the time of biopsy. Increased ALKP activity was present for >6 months in 2 dogs and >12 months in 5 dogs; activity was > 1,000 U/L for at least 1 measurement in 5 dogs. Results of liver function testing, adrenocortical function testing, and hepatic ultrasonography were reviewed. Results of histological examination were normal in 6 dogs. One dog had regional, chronic cholangitis without evidence of cholestasis. The lesion was judged unlikely to account for the degree of hyperphosphatasemia. This study provides evidence of possible benign hyperphosphatasemia in Scottish Terriers or of another familial disorder causing asymptomatical hyperphosphatasemia without corresponding histopathological abnormalities in the liver. Prospective studies of ALKP isoenzyme characterization, investigation of skeletal integrity, evaluation of additional related dogs to determine prevalence, and longer follow-up evaluation are necessary to better characterize this finding.