Many horses get their drinking water from fluoride-supplemented public water systems. Periodically reports show up on the internet and in published articles decrying the harm that a fluoridated water supply causes to humans and animals. These reports usually come from non-peer reviewed sources and are missing important information.
Safe water for horses
Studies are needed to determine safe limits of fluoride in feed and water for horses, however, evidence indicates that fluoride concentrations allowable in US public water systems are well tolerated by horses.
According to an article by Dr. Cynthis Gaskill in the Equine Disease Quarterly, a careful review of peer-reviewed literature in reputable scientific journals showed no published reports documenting fluoride poisoning, also known as fluorosis in horses.
Fluoride is one of the most common elements in the environment and is found naturally in soil, rock, water, air, plants and animal tissue. Low concentrations of dietary fluoride can be beneficial to animals; excessive amounts can cause fluoride poisoning.
Fluorosis can occur in any species including horses. In the past, fluorosis occurred more commonly due to ingestion of forages or waters contaminated with fluoride-containing industrial waste, hifh-fluorine rock-phosphate supplements in animal feed and fluoride-containing rodenticides, insecticides and other chemicals.
Regulations restricting the amount of fluoride in industrial pollution and products containing fluoride have greatly decreased the occurrence of fluorosis, although fluoride poisoning still occasionally occurs in areas with high volcanic activity or through the ingestion of fluoride-containing medications or contaminated water.
Acute high dose poisoning results in severe signs and rapid death. Chronic, lower dose poisoning causes predominantly tooth and bone abnormalities. Teeth are affected during the period of tooth development which in horses is complete before 4 or 5 years of age.
Based on scientific research, public water sources often are supplemented with fluoride to help prevent dental disease in humans. This supplementation is targeted to achieve fluoride concentrations of 0.8 to 1.3 mg/L per the national Safe Drinking Water Act.
In the USA, the EPA recommends a maximum fluoride concentration of 2mg/L in water intended for livestock In Kentucky, the majority of horses drink fluoridated public water and fluorosis is not seen in this horse population.
Studies are needed to determine safe limits of fluoride in feed and water for horses, however, evidence to date indicates that fluoride concentrations allowable in US public water systems are well tolerated by horses and do not cause fluorosis.
By: Dr. Cynthia Gaskill, Equine Disease Quarterly, Accessed 11/21/2013