Prostatic adenocarcinoma with osseous metastases in a dog

Bone scintigraphy was used to diagnose osseous metastasis of prostatic adenocarcinoma in a 10-year-old dog with neck pain and ataxia and a large, sensitive prostate gland. Although radiography revealed a normal spine, prostatic fluid cytologic and ultrasonographic findings were compatible with prostatitis or neoplasia. Scintigraphic hot spots were seen in the axial skeleton, ribs, pelvis, humerus, and femur and corresponded to sites of metastatic prostatic adenocarcinoma.     

Choroidal melanoma in a dog

A 7-year-old intact female golden Retriever was referred for evaluation of an intraorbital mass of the left eye. Based on ophthalmoscopy, ultrasonography and magnetic resonance imaging (MRI), the tentative diagnosis was made as an intraocular neoplasia, especially choroidal melanoma. The orbital exenteration of the affected eye was performed. The mass was histologically diagnosed as malignant choroidal melanoma. No signs of recurrence and metastasis were detected by thoracic radiographs, blood examinations and MR images, and the dog was clinically healthy for 23 months after operation.     

Limb salvage in a dog with chondrosarcoma of the tibia

Limb salvage was accomplished by using a frozen allograft bone and arthrodesis of the stifle joint in a 5-year-old male German Shepherd Dog with a chondrosarcoma in the proximal tibia. At 17 months after surgery, limb function was satisfactory, and thoracic radiography did not reveal evidence of pulmonary metastases.     

Malignant melanoma of the larynx in a dog

Laryngeal dysfunction due to neoplastic disease is rare. Consequently, little is known about the behaviour or treatment of these tumours (Crow 1980). Clinical signs common to most laryngeal tumours include hoarseness and sometimes complete loss of voice (Wheeldon and others 1982). The signs develop over many months and later include stertorous breathing and dyspnoea (Harvey 1981). This case report was a malignant melanoma of the larynx and perilaryngeal tissues.     

Multiple osseous metastases of a carotid body tumor in a dog

Metastasis of malignant carotid body tumor to multiple bones was detected in a 13-year-old female Siberian husky dog. Radiographs exhibited an abnormal mass in the retropharyngeal site and osteolytic lesions in the vertebral bodies, spinous process, tibia, and ribs. At necropsy, multiple masses were observed in the bones as well as at the dorsal area of the retropharynx. Histologically, the tumor cells, arranged in sheets and clusters, had eosinophilic finely granular cytoplasm. Immunohistochemistry showed the tumor cells were positive for neuron-specific enolase and synaptophysin. Electron microscopy demonstrated a number of dense membrane-bound granules in the cytoplasm of the tumor cells. Based on these findings, this case was diagnosed as multiple bone metastases of a malignant carotid body tumor. Spinal cord damage induced by the tumor mass was the cause of the hind limb paralysis of the present dog.     

Intranasal malignant melanoma in a dog

A 10-year-old, female Newfoundland-cross dog was presented for evaluation of chronic intermittent unilateral epistaxis, nasal stertor, and sneezing. Nasal magnetic resonance imaging revealed a 3 x 5-cm mass in the left nasal cavity. Histopathological evaluation of nasal biopsies determined that the mass was a malignant melanoma. The mass was surgically resected and treated with bilateral opposed photon-beam radiation. This is the first report to describe the presentation, diagnosis, and treatment of an intranasal malignant melanoma in a dog.     

Perianal malignant melanoma in a dog

Melanocytic tumors are relatively common in dogs and most often occur in the oral cavity, lip, skin, digit, and eye. There are notable differences in the behavior of these tumors, depending on their anatomical location. The majority of oral melanomas and two-thirds of melanomas arising from the digit are malignant, whereas most of melanomas originating from the haired skin are benign. The anus and perianal areas are very uncommon sites for melanocytic tumors in domestic animals except horses, and most of those tumors in horses are malignant. To our knowledge, perianal malignant melanoma has not been reported in the dog and its prognosis is unknown.     

Malignant ocular melanoma in a dog

A mongrel male dog of three years old was referred to the Seoul National University Veterinary Teaching Hospital following a one month history of glaucoma. On ophthalmic examination, hyphema, glaucoma, uveitis, iridal mass, and loss of vision were noted in the right eye. Ultrasonography and computed tomography revealed a mass with involvement of the entire uvea. Radiographic evaluation did not reveal any evidence of distant metastasis. The right eye was surgically removed because of the high likelihood of neoplasia. A histologic diagnosis of malignant uveal melanoma was made.     

Malignant melanoma involving the aorta in a dog

A four year old female Siberian husky presented with shifting hind limb lameness was euthanized and found to have disseminated malignant melanoma without oral, cutaneous or ocular involvement. The largest and possibly primary mass involved the aorta and sublumbar muscles and occluded as well as penetrated the aorta. Numerous smaller tumors were present in skeletal and soft tissues of both hind limbs, suggesting hematogenous spread from the aortic lesion.     

Primary polycythaemia in a dog

A 7-year-old, crossbred, desexed bitch had a fluctuating illness of more than 6 months duration, with signs of inappetence, reduced exercise tolerance, restlessness, panting, black diarrhoea, and red eyes and ears. Haematological examination disclosed persistent polycythaemia, reticulocytosis, normoblastaemia , and normal total plasma protein concentration when not dehydrated. Splenomegaly was present, but there was no evidence of significant pulmonary, cardiac or renal disease on physical, radiographic or electrocardiographic examination. Further investigations revealed normal arterial Po2 and oxygen saturation, and increased total erythrocyte volume. Primary polycythaemia was diagnosed. The dog was rendered anaemic by bleeding, then treated with a single injection of radioactive phosphorus. The patient has had no recurrence of signs and remains well 50 months later.     

Metastatic balloon cell melanoma in a dog

Background: Balloon cell melanoma is a rare variant of amelanotic melanoma that is difficult to differentiate from sebaceous cell carcinoma, liposarcoma, and other clear cell neoplasms without immunohistochemistry or ultrastructural evidence of melanin or melanosomes. Objective: The purpose of this report was to describe the clinical, cytologic, histologic, immunohistochemical, and ultrastructural findings in a dog with metastatic balloon cell melanoma. Methods: A 6‐year‐old female Golden Retriever was evaluated for a white, flocculent infiltrate in the anterior chamber of the left eye and an enlarged left prescapular lymph node. Cytologic evaluation of the eye and lymph node were performed following aqueocentesis and fine‐needle aspiration, respectively. The affected lymph node was examined histologically and stained for cytokeratin, vimentin, S‐100, and Melan A. Following euthanasia a necropsy was performed and samples of the affected lymph node were examined by electron microscopy. Results: Cytologic examination of the lymph node and aqueocentesis sample revealed round neoplastic cells that had abundant clear vacuolated cytoplasm. A tentative diagnosis of metastatic sebaceous cell carcinoma or clear cell neoplasm was made. Histologically, the affected lymph node had similar polygonal clear cells arranged in sheets and packets divided by delicate fibrovascular stroma. Immunohistochemical staining of the cells was negative for cytokeratin but positive for vimentin, weakly positive for S‐100, and strongly positive for Melan A. At necropsy, metastatic lesions were identified in the diaphragm, heart, lung, kidneys, left eye, prescapular and sublumbar lymph nodes, and multiple skin sites. Ultrastructural examination of neoplastic lymph nodes revealed many membrane‐bound vacuoles, myelinlike figures, and rare melanosomes. Conclusion: Immunohistochemical staining and ultrastructural features of the neoplastic cells supported a diagnosis of metastatic balloon cell melanoma.     

Primary osteosarcoma of the synovium in a dog

An eight-year-old, spayed female Labrador retriever was presented for evaluation of left thoracic limb lameness. Radiographs of the left elbow revealed mineralization of the soft tissues surrounding the joint, with no evidence of periarticular bony lysis. Biopsy of the synovial tissues of the left radiohumeral joint yielded a diagnosis of osteosarcoma (OSA). The dog was treated with palliative radiotherapy, piroxicam, and carboplatin chemotherapy, which resulted in excellent pain control for approximately eight months. Amputation of the affected limb was then performed. Six months later, the dog developed multiple subcutaneous OSA metastases, and the dog was euthanized 15 months after diagnosis due to refractory vomiting. This report documents the first known case of primary OSA of the synovium in any species.     

Primary chondrosarcoma in the liver of a dog

Primary chondrosarcoma was found in the quadrate lobe of the liver of a 6-year-old, intact, male Golden Retriever. At 6 months after partial hepatectomy, recurrence in the liver occurred. The dog died of its systemic metastases 10 months thereafter. Histologically, the hepatic mass revealed neoplastic chondrocytes with abundant chondroid matrix, and there were few myxoid areas where the cellularity and pleomorphism of the neoplastic cells were more prominent. The neoplastic cells were positive for periodic acid-Schiff and were immunohistochemically positive for vimentin and S-100 protein; the matrix was deeply stained for alcian blue and was metachromatic for toluidine blue stain. This tumor might be derived from pluripotent mesenchymal cells in the connective tissue of the liver. To the best of our knowledge, in all mammalians, including humans, this is the first report of extraskeletal chondrosarcoma primarily arising in the liver.     

Multicentric osseous lymphoma with spinal extradural involvement in a dog.

Multicentric osseous lymphoma involving the ribs and multiple vertebrae was observed in a 7-year-old Siberian Husky. Extradural spinal cord compression was treated by surgical decompressive hemilaminectomy of L1-2 without noticeable improvement of signs neurologic dysfunction. However, palliation of signs of pain was noticed after irradiation in conjunction with chemotherapy and surgical decompression.