The domestic reindeer (Rangifer tarandus) from northern Norway as intermediate host for three species of Sarcocystis.

Sections of skeletal and cardiac muscle of reindeer from northern Norway were examined for sarcocysts by light microscopy. In skeletal muscle 3 different types of cysts were demonstrated; thick-walled macroscopic cysts surrounded by a fibrillar layer (Type 1), thick-walled microscopic cysts (Type 2) and thin-walled microscopic cysts (Type 3). In cardiac muscle only thin-walled cysts of type 3 were found. The 3 different types of cysts are considered to be cysts of 3 different species of Sarcocystis infecting the reindeer. Dogs and foxes fed muscular tissue from reindeer started shedding Sarcocystis sporocysts measuring 13.9×10.2 µm and 14.4×10.4 µm, respectively, after a prepatent period of 11–17 days. Dogs and foxes are considered to be definitive hosts for Sarcocystis sp. with type 3-cysts. The original descriptions of Sarcocystis grueneri are critically reviewed and found to be inadequate. By comparing the size, cyst wall morphology and location of the cysts in the present investigation with those of the original papers, it is found that Sarcocystis sp. with type 3-cysts in all likelihood is identical with Sarcocystis grueneri. The name Sarcocystis grueneri is retained and assigned to the Sarcocystis sp. with type 3-cysts in cardiac and skeletal muscle of reindeer. The dog (Canis familiaris), the silver fox (Vulpes vulpes) and the blue fox (Alopex lagopus) are recorded as definitive hosts for Sarcocystis grueneri.