Dilation of the vagina (Figure 1 and Figure 2) usually occurs secondary to an imperforate vagina. An endodermal membrane normally occludes the vagina in the pup, and this typically disappears at puberty and the vagina becomes patent. When this does not happen, the consequence is cystic dilation of the vagina. This dilation may also be associated with mucometra, inflammation, and hyperplasia of the epithelium.
Vagina - Dilatation should be diagnosed and graded when the cause of the dilation is not apparent on the slide. However, if the vagina is imperforate, and this is apparent on the slide, then the diagnosis of imperforate vagina should be made. Secondary lesions, such as inflammation, should not be diagnosed separately unless warranted by severity.
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