Skin and respiratory diseases, as well as tumours are the most frequently diagnosed diseases in pet rats. From among all the types of tumours found in this species of animals, fibrosarcoma is rarely observed. In this clinical case, a fast growth of fibrosarcoma and it is expansion in the left middle and inner ear led to a head tilt (torticollis) and facial nerve paralysis on the same side and were a decisive argument for euthanasia. The aim of the study was to reveal that the individual approach to each patient and a thorough clinical examination are extremely important. They allow to avoid mistakes, put a correct diagnosis and start an appropriate treatment.

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