Metastatic Adenocarcinoma of the Mammary Gland in a Père David's Deer

Abstract

A 4-year-old female Pere David’s deer (Elaphurus davidianus) was found in lateral recumbency and submitted to the College of Veterinary Medicine, Kansas State University. The animal, 1 of 40 in a privately owned herd, had been inactive and had continually licked its inguinal area for the previous 3 weeks. The deer remained sternally recumbent during the physical examination and was depressed, moderately dehydrated, and very thin (118 kg) and had a temperature of 39.5 C. The teats were recognizable, but the mammary tissue was replaced by multiple firm nodules that extended cranially along the lymphatics of the ventral midline and caudally into the inguinal area. A necrotic area in the cranial mammary gland was infested with fly larvae. The owner did not know if the animal had ever lactated. Differential diagnoses included trauma, foreign body with secondary infection, and neoplasia. The prognosis was guarded. Serum chemistries and hematology showed anemia, with leukocytosis (13.5 x 10, n = 5.1 ± 3.1), hyperphosphatemia (13.1 mg/dl, n = 6.3 ± 1.3), hypocalcemia (8.0 mg/ dl, n = 9.6 ± 0.8), and elevated aspartate aminotransferase (268 U/liter, n = 95 ± 80). Radiographic evaluation of the area revealed a large wound on the caudoventral abdomen with multiple fistulas. Cytologic examination of the nodules was conducted. Cellularity was low to moderate and consisted of irregularly shaped individual cells or cells in clusters. Nuclei were round to oval, located centrally or slightly eccentrically, and had coarse reticular chromatin and prominent nucleoli. Anisokaryosis was slight to moderate, but an occasional large nucleus was seen, and multinucleated cells had > 4 nuclei. Findings were suggestive of a carcinoma rather than a granulomatous response. The animals condition deteriorated, and it died. On necropsy, the entire mammary gland was enlarged, firm, and nodular and had an open necrotic area 14 cm wide and 4 cm deep. From the umbilicus caudal to the mammary gland, the subcutaneous tissue contained multiple nodules. The largest one was 6-8 cm, with a necrotic center containing brownish opaque fluid. Subcutaneous tissue along both sides of the body was firm and whitish. The medial side of the right hind leg had 8x 10-cm streaks of flat, firm, whitebrown tissue within the muscle radiating downward from the inguinal area. A smaller 2x 3-cm area was present on the left hind leg. Both prefemoral lymph nodes of both legs were 8 cm with caseous centers. Popliteal lymph nodes were 3 cm, white, and firm. Reddish, opaque, watery fluid was present in the thoracic cavity. The lungs had multiple, 1-4-cm, slightly raised, white nodules with occasionally necrotic centers. Reddish, raised