Ocorrência de neoplasias em cães e gatos da mesorregião metropolitana de Belém, PA entre 2005 e 2010 / Occurrence of neoplasms in canine and feline from the Metropolitan Mesoregion of Belém, PA from 2005 to 2010

Data on the occurrence of cancers in dogs and cats from the Metropolitan Mesoregion of Belém are not available in the literature. This paper describes the occurrence of neoplasms in these species from 2005 to 2010. The canine cutaneous system was the most affected in this study (47 percent), followed by the mammary gland (39 percent), reproductive system (4 percent), oral cavity (4 percent), bones and joints (2 percent), ocular system (1.5 percent), digestive system (1.5 percent) and urinary tract (1 percent). In feline species, the mammary gland accounted for 87.8 percent, followed by the cutaneous system (6 percent), respiratory system (3 percent) and oral cavity (3 percent).

Ethidium bromide-induced demyelination of the sciatic nerve of adult Wistar rats

Peripheral nerve ultrastructure was assessed after single or multiple local injections of the intercalating dye ethidium bromide. Thirty-four adult Wistar rats of both sexes were divided into five groups and maintained in a controlled environment with rat chow and water ad libitum throughout the experiment. The experimental animals were injected with 1 æl of 0.1 percent ethidium bromide in 0.9 percent saline into the central third of the left sciatic nerve 1 (group 1), 2 (group 2), 4 (group 3), 6 (group 4) or 8 (group 5) times. In groups 2 to 5 the injections were made at 28-day intervals. Control animals received the same amount of 0.9 percent saline. The animals were killed at different times after injection: group 1 at 7 days (2 rats) and 15 days (2 rats); for groups 2, 3, 4 and 5, all rats were killed 10 days after the last injection and the lesions were investigated by light and transmission electron microscopy. In the acute lesions, intoxicated Schwann cells showed a vacuolated cytoplasm and separation of the sheaths from the axon. Myelin sheaths underwent progressive vesiculation and subsequent segmental demyelination. Myelin debris were withdrawn by macrophages and remyelination by Schwann cells was prominent. With the increase in the number of injections collagen fibers also increased in number and progressively enveloped smaller numbers of remyelinated axons composing new fascicles. Wallerian degeneration of fibers apparently not affected by ethidium bromide was more intense in the nerves from groups 4 and 5. The peripheral nerve repairs itself after demyelinating challenges with a profusion of collagen fibers and new fasciculations. This experimental model is valid to mimic recurrent demyelinating neuropathies