A female, 1.5 years old, mixed‑breed dog, was presented for left hind limb lameness. Radiographs revealed an irregular periosteal proliferation on the left iliac wing. The clinical condition worsened with generalised enlargement of the lymph nodes, azotaemia, and pyelonephritis. The magnetic resonance imaging of the pelvis and a surgical biopsy diagnosed a mycotic myositis and osteomyelitis of the iliac wing and gluteal muscles. Aspergillus terreus was isolated from culture of urine and lymph nodes aspirates. The antifungal susceptibility test showed moderate sensitivity to Itraconazole. After one month of therapy with itraconazole, the dog presented discospondylitis of L1‑L2 and partial ureteral obstruction due to mycotic bezoar that was resolved with medical treatment and itraconazole dose elevation. After twelve months, itraconazole was suspended; a severe osteomyelitis of the left femur developed, and the dog was euthanised. The necropsy confirmed the presence of mycotic osteomyelitis of the iliac wing and femur, discospondylitis, lymphadenitis and severe granulomatous pyelonephritis. Systemic aspergillosis has rarely been reported in the literature, especially in Italy. The pelvic bone involvement is rare both in dogs and humans. Although itraconazole treatment allowed remission of the clinical signs for one year, it was not able to cure the dog.