Chondrosarcoma is a malignant tumor that is characterized by the formation of cartilage by tumor cells. The tumor is commonly observed in regions where cartilage is already present. It is the second most common primary tumor of the bone in both humans and dogs that accounts for approximately 5% to 10% of all canine primary bone tumors. Golden retrievers have about 3 times greater risk of developing chondrosarcoma than any other breed. Nasal chondrosarcoma is the most common tumor of the nasal passages in the dog (28.8%), followed by the ribs (17.5%), appendicular skeleton (17.5%), extraskeletal sites(13%), and facial bones. Because chondrosarcoma is highly resistant to chemotherapy and radiotherapy, surgical treatment is the only option for curative treatment. The median survival time for dogs with skeletal chondrosarcoma varies between 201 and 1080 days, with treatment, depending upon the location and type of the tumor.3.
Two common types of chondrosarcoma are recognized: myxoid, the most common type found in skeletal tumors, and mesenchymal, a rarer type found more often in extraskeletal sites. Most chondrosarcomas develop from the skeletal cartilage, but some extraskeletal chondrosarcomas occur in the tissues that possess preexisting cartilage. In dogs, some extraskeletal chondrosarcomas occur in the heart and lung, including cartilage, whereas others were seen in the spleen, where no cartilage originally existed.
Extraskeletal mesenchymal chondrosarcomas in the lungs, heart, skull, and spleen are extremely rare tumors (1%).4 Rib-based chondrosarcomas may have few or no clinical problems, but intranasal chondrosarcomas often present with sneezing, bleeding nasal obstruction, discharge, and gurgling sounds from the nares.2 The most frequently reported clinical sign in dogs with chondrosarcoma involving the facial bones (included all the bones of the skull not associated with the nasal cavity or paranasal sinuses) is a mass or swelling over the affected area.5
The tumor tends to grow more slowly and develop metastasis later and with much less frequency than osteosarcoma. Metastasis, when it does occur, is usually to the lungs, but other organs, such as the kidney, heart, liver and skeleton may also be affected. Surgical removal of chondrosarcomas in accessible locations, such as ribs and limbs is curative more often than for osteosarcomas. For dogs with long bone chondrosarcoma, the average survival time after limb amputation alone (no chemotherapy) is about 1.5 years. Untreated canine intranasal tumors carry a poor prognosis.6 Chemotherapy does not decrease the metastatic rate or improve survival time in dogs with chondrosarcoma.
Chondrosarcoma of the skull is a slow-progressing malignant disease which occurs locally, aggressive with invasion into the surrounding tissues. It can develop out of the tissues where cartilage normally does not exist. Dogs with chondrosarcoma of the skull have life expectancy between 210 and 580 days. In cases of retrobulbular chondrosarcoma, due to impossibility of the eye closure, the cornea gets dry and keratitis and conjunctivitis can be observed. The eye affected by CS of the orbit is non-functional, and due to destruction of the nasal septum and expansion of the tumor, a thick nasal discharge, difficult breathing and nasal stridor are also present. Prognosis for the orbital tumors is poor since the surgical treatment does not solve the issue of recurrences.7
- A Handbook of Veterinary Parasitology: Domestic Animals of North America. Henry Joseph Griffiths
- Textbook of small animal medicine. John K. Dunn
- Canine Medicine and Disease Prevention
- Primary splenic mesenchymal chondrosarcoma in a dog
- Primary chondrosarcoma in the skull of a dog
- Intraoperative acridine orange photodynamic therapy and cribriform electron-beam irradiation for canine intranasal tumors: A pilot study
Takuya Maruo, Koichi Nagata, Yasuhiro Fukuyama, Yuki Nemoto, Shinpei Kawarai, Yukihiro Fujita, and Tomohiro Nakayama
- Retrobulbar chondrosarcoma in a dog. M. Ralić, J. Vasić, M. Jovanović, and B. Cameron