A dog in the Iditarod Trail Sled Dog Race died Saturday. The 7-year-old male, named Zaster, is the first dog death in this year’s race.

Rookie musher John Stetson left the dog with officials at the Ophir checkpoint early Friday. The dog had been showing signs of pneumonia. Iditarod race marshal Mark Nordman says tests will be done to determine the cause of death.

Stetson is from Duluth, Minn., and is 60th in the standings. He was at the Cripple checkpoint, 503 miles into the 1,100-mile race.