VITAMIN AND MINERAL DEFICIENCIES AND TOXICITIES
Vitamin A
Deficiency: Night blindness; excessive tearing; hypokeratinization of the cornea and skin; anorexia; poor growth; respiratory infections; sublingual salivary gland abscesses; impaired conception; elevated cerebrospinal fluid pressure; convulsive seizures; progressive weakness; declines in plasma, liver and kidney Vitamin A concentrations.
One of the chief functions of Vitamin A is to keep mucous membranes healthy so that they will resist infection and diseases of the respiratory system. With deficiency comes a higher rate of pneumonia. RACEHORSES: stable cough.
BROODMARES: often results in lowered conception and rates of reproduction due to improper acid balance and inadequate lubrication of the vagina and uterus. Often mares abort their foals or they are born dead or weak. FOALS: slow growth; cold in head with nasal discharge, and sometimes with a cough and scours. STALLIONS: long deficiency of Vitamin A may affect the fertility of stallions by causing the degeneration of the sperm-producing cells.
Toxicity: bone fragility; hyperostosis; exfoliated epithelium; and teratogenesis. Rough haircoat; poor muscle tone; depression; hair and epidermis loss. Ataxia.
Vitamin D
Deficiency: poor appetite; slow growth; decreased bone strength and density.
Toxicity: Calcification of blood vessels, heart, soft tissue. Bone abnormalities; limb stiffness; weight loss.
Vitamin E
Deficiency: Pale diffuse or linear areas in skeletal and Cardiac muscle. Hyaline andgranular degeneration as well as swelling and fragmentation of muscle fibers, including the tongue, to cause interference of nursing in foals and performance. (This is why we see tongue ties on many racehorses.) Subcutaneous and intramuscular edema; pulmonary congestion; degenerative myelopathy. Myelin sheaths dilated and vacuolated. Neuronal degeneration, ataxia and incoordination. Symmetric ataxia, paresis, and laryngeal adductor, cervicofacial, local cervical and cutaneous trunci
hyporeflexia, resulting in gait abnormality.
Toxicity: Interference with utilization of other fat soluble vitamins. Coagulopathy in Vitamin K deficient diets.
Vitamin K
Deficiency: Decreased thrombin production resulting in decreased fibrin production which increases susceptibility to hemorrhage.
Toxicity: Renal colic; hematuria; azotemia; electrolyte abnormalities
consistent with renal failure.
Thiamine
Deficiency: Anorexia; weight loss; ataxia, bracycardia; missing heartbeats; muscular fasciculations; periodic hypothermia of hooves, ears and muzzle.
Toxicity: Appears to block nerve transmission; restlessness, convulsions, cyanosis, labored breathing, death.
Riboflavin
Deficiency: Rough hair coat; atrophy of the epidermis, hair follicles, and sebaceous glands; dermatitis; vascularization of the cornea; catarrhal conjunctivitis; photophopia; excessive tearing; still births.
Toxicity: Possible lower rates of ovulation.
Niacin
Deficiency: Has not been described in the horse. Other species: inflammation of the lingual and buccal surfaces, followed by necrosis, ulceration, foul breath, dermatitis, and hemorrhagic enteritis.
Toxicity: Has not been described in the horse. Other species: Vasodilation; itching; sensations of heat.
Pantothenic Acid
Deficiency: Has not been described in the horse. Other species: dermatitis;
achromotricia; enteritis; neuritis; degenerative changes in peripheral motor nerves which impair muscle function.
Toxicity: No adverse reactions in any species.
Vitamin B6 (pyridoxine)
Deficiency: Has not been described in the horse. Other species: Scaly dermatitis; alopecia; microcytic, hypochromic anemia; immune function; neurological abnormalities.
Toxicity: Has not been described in the horse. Other species: Lack of coordination; ataxia; convulsions; bilateral loss of myelin; neuropathy involving degeneration of the dorsal root ganglia, gasserian ganglia and sensory nerve fibers.
Biotin
Deficiency: Has not been described in the horse. No unequivocal evidence of Biotin deficiency has been established. Biotin is manufactured in the horse's gut.
Toxicity: Has not been described in the horse. Other species: Fetal reabsorption.
Folacin
Deficiency: Has not been described in the horse. Other species: Megoblastic anemia, macrocytosis.
Toxicity: Has not been described in the horse. Other species: Epileptic convulsions, renal hypertrophy.
Vitamin B-12
Deficiency: Has not been described in the horse. Other species: Normocytic,
normochromic anemia, neurological abnormalities.
Toxicity: None indicated in any species.
Ascorbic Acid
Two researchers reported improved sperm quality in stallions and in the breeding performance of mares.
Deficiency and Toxicity have not been recorded in the horse. Reports in other species of toxicity were incidental and were noted in uncontrolled studies, or are controversial.
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