Chronic fluoride (F) intoxication in the form of osteo-dental fluorosis was observed in 23 domestic equus animals, 9 to 23 years old, including 14 horses (Equus caballus), and 9 donkeys (E. asinus) living in F endemic areas of Dungarpur district, Rajasthan, India. The mean F concentration in the drinking water in these areas ranged from 1.4 to 3.3 ppm. Eleven (78.7%) of these horses and all nine donkeys were afflicted with mild to severe dental fluorosis. Their incisor teeth were brown to black-yellowish in color. Also present as indications of more severe chronic F intoxication were irregular wearing and excessive abrasions of the teeth, deep dark-yellowish discoloration of exposed cementum and/or remaining enamel surface, and pronounced loss of tooth-supporting alveolar bone with recession of gingiva. Excessive hypoplasia and light brown-yellowish pigmentation on the enamel surface of incisors were also observed in 2 foals below the age of 2 months.
Among the mature animals, the following manifestations of skeletal fluorosis were present: periosteal exostoses in mandibular regions, ribs, metacarpus, and metatarsus, intermittent lameness, hoof deformities, and hardness of tendons in the legs. Other signs of F intoxication included colic, diarrhoea, retention of urine, repeated abortions, and sterility were noted. This evidence of osteo-dental fluorosis in domestic horses and donkeys is reported for the first time in India, and this condition in donkeys is reported for the first time anywhere.