Suspected chronic fluorosis in a sheep flock

Area of Science:

• Veterinary Medicine
• Animal Nutrition
• Toxicology

Background:

• Non-defluorinated rock phosphate is a common mineral supplement for livestock.
• Fluoride toxicity, or fluorosis, can cause significant health issues in sheep.
• Assessing the risk of fluorosis from specific mineral sources is crucial for animal health management.

Purpose of the Study:

• To investigate an outbreak of suspected chronic fluorosis in a Döhne Merino sheep flock.
• To identify the causative agent and risk factors associated with the fluorosis outbreak.
• To provide recommendations regarding the use of non-defluorinated mineral sources in sheep diets.

Main Methods:

• Observational study of a Döhne Merino sheep flock experiencing clinical signs of fluorosis.
• Analysis of the mineral lick composition, including fluoride content.
• Correlation of affected animals with age, breed component (commercial vs. stud), and body condition.

Main Results:

• An estimated daily intake of 107g of a lick containing 3.4% non-defluorinated rock phosphate (2.5% fluoride) was linked to the outbreak.
• Affected animals included 37% of commercial 4-tooth sheep and 17% of stud sheep of the same age.
• Younger sheep and those in poorer body condition exhibited higher susceptibility to fluorosis.

Conclusions:

• Non-defluorinated rock phosphate in mineral licks can lead to chronic fluorosis in sheep.
• Sheep age and nutritional status significantly influence susceptibility to fluoride toxicity.
• Non-defluorinated, non-registered mineral sources should be excluded from supplementary sheep rations to prevent fluorosis.