We examined the cerebellum and cerebrum of 4 vaccinated dogs, 3–60-mo-old, that displayed clinical signs of canine distemper virus (CDV) infection, and died 7–40 d after developing neurologic signs. The main histologic lesions were demyelination, gliosis, meningitis, perivascular lymphocytic cuffing, and inclusion bodies. These lesions were similar in all 4 cases regardless of the time since vaccination, except that meningoencephalitis and gliosis were subacute in 3 dogs and chronic in 1 dog. However, these differences did not appear to be related to their vaccination status. Immunohistologically, a CDV-positive immunoreaction was seen mainly in astrocytes, neurons and their axons, lymphocytes around and in the blood vessels of the pia mater and choroid plexus, ependymal cells of each ventricle, and the cells of the choroid plexus. The histologic and immunohistologic changes were similar in the cerebellum and cerebrum. The genetic characterization of the virus strains in 2 of these naturally occurring canine distemper cases confirmed that they were South American wild-type strains (Kiki and Uy251) belonging to the EU1/SA1 lineage. These strains are not included in the commercial CDV vaccines available in Uruguay.

我们检查了 4 只 3-60 岁已接种疫苗的狗的小脑和大脑，这些狗表现出犬瘟热病毒 (CDV) 感染的临床症状，并在出现神经系统症状后 7-40 天死亡。主要的组织学病变是脱髓鞘、神经胶质增生、脑膜炎、血管周围淋巴细胞套囊和包涵体。这些病变在所有 4 例中都相似，无论接种后的时间如何，除了脑膜脑炎和神经胶质增生在 3 只狗中是亚急性的，在 1 只狗中是慢性的。然而，这些差异似乎与他们的疫苗接种状态无关。免疫组织学上，CDV阳性免疫反应主要见于星形胶质细胞、神经元及其轴突、软脑膜和脉络丛血管周围和中的淋巴细胞、每个心室的室管膜细胞和脉络丛细胞。小脑和大脑的组织学和免疫组织学变化相似。在其中 2 例自然发生的犬瘟热病例中，病毒株的遗传特征证实它们是属于 EU1/SA1 谱系的南美野生型毒株（Kiki 和 Uy251）。这些毒株不包括在乌拉圭的商业 CDV 疫苗中。