Serum biochemistry of captive and free-ranging gray wolves (Canis lupus)

Peter Constable, Ken Hinchcliff, Nick Demma, Margaret Callahan, Bruce Dale, Kevin Fox, Layne Adams, Ray Wack, Lynn Kramer

Research output: Contribution to journalArticlepeer-review


Normal serum biochemistry values are frequently obtained from studies of captive sedentary (zoo) or free-ranging (wild) animals. It is frequently assumed that values obtained from these two populations are directly referable to each other. We tested this assumption using 20 captive gray wolves (Canis lupus) in Minnesota, USA, and 11 free-ranging gray wolves in Alaska, USA. Free-ranging wolves had significantly (P < 0.05) lower sodium, chloride, and creatinine concentrations and significantly higher potassium and blood urea nitrogen (BUN) concentrations; BUN to creatinine ratios; and alanine aminotransferase, aspartate aminotransferase, and creatine kinase activities relative to captive wolves. Corticosteroid-induced alkaline phosphatase activity (a marker of stress in domestic dogs) was detected in 3 of 11 free-ranging wolves and in 0 of 20 captive wolves (P = 0.037). This study provides clear evidence that serum biochemical differences can exist between captive and free-ranging populations of one species. Accordingly, evaluation of the health status of an animal should incorporate an understanding of the potential confounding effect that nutrition, activity level, and environmental stress could have on the factor(s) being measured.

Original languageEnglish (US)
Pages (from-to)435-440
Number of pages6
JournalJournal of Zoo and Wildlife Medicine
Issue number4
StatePublished - Dec 1998


  • Activity level
  • Corticosteroid-induced alkaline phosphatase
  • Exercise
  • Gray wolf

ASJC Scopus subject areas

  • Animal Science and Zoology
  • veterinary(all)


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