Due to excess levels of GH after closure of the physeal plates. As the bones cannot increase in length they respond by appositional growth.
General increase in tissue mass throughout the body. Skin is thickened and forms folds. Also:
- Large paws.
- Prognathism with an overshot lower jaw.
- Dyspnoea due to overgrowth of tissues around the larynx.
- Neurological signs due to overgrowth of the bony parts of the skull.
Most often iatrogenic due to progestagen therapy in dogs. Progestagens stimulate the release of GH from mammary tissue in dogs and bitches. In the cat, aetiology is often neoplasia.