The dorsal hair ridge in Rhodesian and Thai Ridgeback dogs is caused by a dominant mutation that also predisposes to the congenital developmental disorder dermoid sinus. Here we show that the causative mutation is a 133-kb duplication involving three fibroblast growth factor (FGF) genes. FGFs play a crucial role in development, suggesting that the ridge and dermoid sinus are caused by dysregulation of one or more of the three FGF genes during development.

Twenty‐seven hunting dogs with local swellings on the thoracic and, or, abdominal wall, were treated mainly by radical surgery supported by chemotherapy. The lesions were characterised histopathologically as pyogranulomatous inflammation. One of the dogs died during surgery because of a technical accident. Four of the dogs underwent further surgery because of relapse. Treatment was successful in 26 cases, with a mean observation period of 3.3 years (range, 0.6 to 6.5 years) without signs of disease. In 12 of the 26 dogs which underwent surgery, parts of grasses (Poaceae family), usually the floret, were found in the lesions. Predominantly anaerobic bacteria (including actinomyces) common to the oropharyngeal tract were isolated from lesions. It is proposed that the plant material is inhaled during open‐mouth breathing and, after migration through the lungs to the peripheral attachment of the diaphragm, causes productive inflammation by synergism with endogenous microorganisms of mucous membrane origin.

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