Shyatt won't be with the Cowboys (14-7, 5-3 Mountain West) when they play at New Mexico on Wednesday, he said in a text message to Katz. The illness is not life-threatening, reports the Casper Star-Tribune.
The coach also missed Wyoming's 74-57 win over Utah State on Saturday.
Assistant coach Scott Duncan is hopeful Shyatt can return for Saturday's game at UNLV, he told Katz.
Said Duncan: "He still has it but not enough energy."
Shyatt coached Wyoming in the 1997-98 season before leaving for Clemson, where he was 70-84 in five seasons. After eight seasons as an assistant at Florida, he returned to the Cowboys.SI WIRE: Arizona's Brandon Ashley out for season with foot injury