The INHAND Project (International Harmonization of Nomenclature and Diagnostic Criteria for Lesions in Rats and Mice) is a joint initiative of the Societies of Toxicologic Pathology from Europe (ESTP), Great Britain (BSTP), Japan (JSTP), and North America (STP) to develop an internationally accepted nomenclature for proliferative and nonproliferative changes in rats and mice. The purpose of this publication is to provide a standardized nomenclature for classifying changes observed in the hematolymphoid organs, including the bone marrow, thymus, spleen, lymph nodes, mucosa-associated lymphoid tissues, and other lymphoid tissues (serosa-associated lymphoid clusters and tertiary lymphoid structures) with color photomicrographs illustrating examples of the lesions. Sources of material included histopathology databases from government, academia, and industrial laboratories throughout the world. Content includes spontaneous lesions as well as lesions induced by exposure to test materials. The nomenclature for these organs is divided into 3 terminologies: descriptive, conventional, and enhanced. Three terms are listed for each diagnosis. The rationale for this approach and guidance for its application to toxicologic pathology are described in detail below.

A study in young beagle dogs was performed in which the animals were treated for 2 weeks with ciprofloxacin at oral doses of 0, 10, 30 or 90 mg/kg per day. Immediately after treatment half of the number of animals were killed and all weight-bearing joints were subject to a thorough gross and histopathological investigation, including special staining of the cartilage matrix, and immunohistochemistry as well as electron microscopy. The remaining animals were maintained for an additional 5-months treatment-free period before being killed. Again, all weight-bearing joints were subject to a thorough gross and histopathological investigation. After 14 days of treatment with ciprofloxacin, oral doses of 30 and 90 mg/kg induced the characteristic arthropathy (blisters, erosions) in juvenile beagle dogs. As expected the lesions persisted while the animals were growing. In contrast, and to our knowledge demonstrated for the first time, an oral dose of 10 mg/kg ciprofloxacin did not induce joint lesions after short-term treatment in juvenile beagle dogs and was also not associated with arthrotoxicity when the dogs became older.

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