A filamentous fungus that caused a fatal systemic infection in a dog has been identified as the new species Sagenomella chlamydospora. When the case was initially reported, the fungus was identified as Paecilomyces sp. This study emphasizes how difficult can be the identification of the causative agent of an infection when an uncommon microorganism is involved. This is the first time that this genus has been involved in animal infections, including humans.