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Melanomas are the most common malignant oral neoplasm in dogs. Osteocartilaginous differentiation in oral melanomas is a rare feature described both in veterinary and human medicine. Here, 10 cases of this type of neoplasm were used to study their immunohistochemical, biological, and clinical characteristics. Reactivity for S100 and melan A antigen was evaluated, and 4 prognosis factors (mitotic index, invasiveness of epithelium, nuclear atypia, and proliferation index) were analyzed and correlated with the clinical course of the neoplasms after diagnosis. Immunohistochemical analysis of the studied neoplasms, including the osteocartilaginous areas, showed positive immunoreaction for S100 and melan A, except in one dog, which was negative for melan A. Analysis of the results showed that oral melamonas with osteocartilaginous differentiation have a clinical course similar to that of other melanomas in the oral cavity. Analysis of the mitotic index and the expression of proliferation marker Ki-67 could be useful tools for predicting the biological behavior of these neoplasms.

A Chlamydophila abortus-induced abortion model was carried out on the basis of the experimental infection of ewes at day 75 of gestation. The infection induced abortions and the birth of weak lambs during the last 3 weeks of pregnancy. To study the kinetics of the infection in the placenta and in other organs, infected ewes were killed at 105, 120, and 130 days of gestation and also several days after abortion or parturition. Infected ewes developed a systemic infection that caused a mild and transient pneumonia and focal hepatitis. Pathologic changes were observed in placentas at 120 day of gestation, although the lesions varied between animals and even between placentomes of the same placenta. The first placental area infected was the maternal stroma and epithelium next to the intercaruncular areas, where neutrophilic response seemed to control the infection. A substantial degree of multiplication of C. abortus was then observed in the trophoblast cells of the placentome, periplacentomal choriallantoic membranes, and hilius, with an inflammatory exudate composed mainly of neutrophils, some macrophages, and very scarce lymphocytes. After abortion, the lesions affected the intercotyledonary areas of the aborted placentas, whereas in the uterus significant lymphocyte infiltration was observed, together with a rapid decrease of the C. abortus antigen in the degenerated caruncular tissues.

A direct relationship has been firmly established between cyclooxygenase-2 (COX-2) expression and malignant behavior in human melanoma. This report examines the relationship between COX-2 expression and tumor location, mitotic and proliferative indices, degree of T CD3 þ lymphocyte infiltration, overall survival, and frequency of recurrence and metastasis of 57 melanocytic tumors (25 oral and 32 cutaneous). COX-2 was highly or moderately expressed in 88% of oral neoplasms (22 of 25), whereas for their cutaneous counterparts, COX-2 expression was low or insignificant in 75% of cases (24 of 32). High and moderate COX-2 expression levels were observed in 73% of melanocytic tumors with a mitotic index ! 3 per 10 high-power fields (26 of 36), whereas in 81% of tumors with a mitotic index < 3 (17 of 21), expression was mild or absent. There were 41 cases with known clinical outcomes; of those showing high, moderate, and mild COX-2 expression, 83.3% (10 of 12), 37.5% (3 of 8), and 25% (2 of 8) died, respectively, whereas 100% of animals showing no COX-2 expression (13 of 13) were still alive at the last follow-up. COX-2 expression was statistically correlated with tumor location, mitotic and percentage Ki-67 proliferative indices, and overall survival, frequency of neoplastic recurrence and metastasis. Regression analysis also showed disease-specific predictive value for COX-2 expression for subjects with melanocytic neoplasms. Additionally, only high COX-2 expression showed significant differences in overall survival, in comparison with moderate, mild, or absent expression. These results suggest that high COX-2 expression may be considered a prognostic biomarker and potentially as a target for therapeutic and preventive strategies in canine melanocytic neoplasms. Keywords cyclooxygenase-2, canine, melanoma, prognosisCanine melanocytic neoplasms occur most frequently in the skin and oral cavity. Classically, body location is one criterion used to establish a prognosis of these tumors. 1,7,10,36 In the skin, melanocytic neoplasms account for 4 to 20% of all cutaneous neoplasms, of which fewer than 5% are malignant. 16,32 Yet canine oral melanomas account for 30 to 40% of all neoplasms in the head and are considered malignant, 36 with poorer prognosis and lower survival rates than their cutaneous melanocytic counterparts. The reasons for this more aggressive behavior are not clear. Recent data suggest that this malignancy may be due to a higher atypia and proliferation rate observed in oral melanomas.27,37 However, several reports suggest a lack of correlation between tumor location and clinical course. 6,20 Of the extensive number of factors used in human pathology to establish an accurate prognosis of melanocytic neoplasms, 40 the mitotic index and Ki-67 proliferation index are the factors that have shown the best correlation with clinical outcome of canine melanocytic neoplasms. 27,[34][35][36][37] Although the mitotic index is considered the most reliable feature for establishing the biological behavior of cu...

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A 1.5-year-old, 23 kg intact male Dalmatian dog was evaluated for acute respiratory insufficiency without a previous history of trauma or toxic exposition. Imaging revealed pneumomediastinum, pneumothorax, diffuse unstructured interstitial pulmonary pattern, pulmonary interstitial emphysema, and pneumoretroperitoneum. Histopathological evaluation of the lungs revealed perivascular and peribronchial emphysema, mild lymphocytic interstitial pneumonia with atypical proliferation of type II pneumocytes in bronchioles and alveoli. A lung disease resembling fibrosing interstitial pneumonia in man and cats has been previously reported in Dalmatians and should be included as a differential diagnosis for Dalmatians with this combination of clinical and imaging characteristics.