High-Oxalate Grasses and Calcium Deficiency
Diets with a calcium:oxalate ratio of 0.5 or less are considered unsafe. Grasses with oxalate levels greater than 0.5% (i.e., 5g of oxalate/kg of grass) are hazardous and can lead to calcium deficiency, osteoporosis, osteodystrophia fibrosa (ODF), nutritional secondary hyperparathyroidism (NSH), and 'bighead'.
High-Oxalate Grasses Types and Locations:
Signs of Calcium Deficiency in Horses:
The first symptom is usually lameness, characterized by an insidious shifting lameness, general tenderness of the joints, and a stiff, stilted gait.
Ill thrift, weight loss, and a rough coat may occur; some horses prefer to lie down.
Some horses exhibit muscular weakness and prefer to canter rather than trot.
Spontaneous avulsion of ligaments and spontaneous fractures can occur.
Pica (dirt eating) and chewing problems (due to loosening of the teeth) can occur.
Note: ‘Bighead’ is just one sign of NSH, found in less than 15% of affected horses.
Jenquine Calsorb Forte® includes Bone Formula for horses that are not regularly hand-fed. Weighing the blocks weekly is a useful way to monitor intake.
Jenquine Bone Formula Forte® can be fed with 60–120g of finely powdered calcium carbonate (lime) to provide extra calcium for 'mopping' up free oxalate. The amount of Jenquine Bone Formula Forte® and lime can be adjusted based on your treating veterinarian’s clinical assessment.
Dr Jennifer Stewart
BVSc BSc PhD Equine Veterinarian and Consultant Nutritionist
