The sites are among 15 animal burial sites left underwater by the worst flooding in the region in more than 100 years, RIA Novosti reported.
Health Minister Veronika Skvortsova said tests have not found any evidence anthrax from the sites had spread to other areas. Spores of the bacteria that cause anthrax can live at burial sites for decades.
The Russian defense ministry said Saturday it had evacuated 8,400 people from flood-hit areas in the region. The rescue effort has so far involved 5,200 service members, 941 military vehicles, nearly 50 aircraft and 40 boats.
Skvortsova said mobile hospitals had provided medical assistance to more than 37,000 people. More than 3,000 people were hospitalized.
Saturday morning, the region's Amur River was almost 6 feet above flood stage, having risen 4.7 inches in the previous 24 hours, the local weather service said.
Flooding has affected the Amur Region, the Jewish Autonomous Region and the territories of Khabarovsk and Primorye, as well as the Siberian republic of Yakutia.
Russian meteorologists say the flooding is the worst in 120 years.
A presidential envoy said Tuesday damage from the flooding is estimated at $1 billion.