Nutrition Deficiencies in Horses

Selenium

• Selenium deficiency leads to decreased serum selenium levels and increased AST activity, resulting in white muscle disease and potential rhabdomyolysis in horses.
• Excess selenium, even at low levels (5 ppm), can cause loss of mane and tail hairs and sloughing of hooves.

Vitamins

• Vitamin A Deficiency

  • Results from feeding dried, poor-quality roughage over time.
  • Symptoms may take months to manifest; includes nyctalopia, keratinization of the cornea, pneumonia susceptibility, incoordination, and deformed hooves.

• Vitamin E

  • Highly labile, quickly lost during storage in feeds and hays.
  • Acts as an important antioxidant; deficiency linked to rhabdomyolysis, impaired immunity, reproductive failure, and ocular lesions.

• Vitamin D

  • May not develop deficiency if horses consume sun-cured hay or are exposed to sunlight.
  • Prolonged confinement can lead to reduced bone calcification, joint stiffness, irritability, and low serum calcium/phosphorus levels.

Minerals

• Magnesium

  • Deficiency in foals fed low magnesium diets results in hypomagnesemia, nervousness, tremors, ataxia, and possible death.
  • Common feeds typically exceed the 70-100 mg/kg dry ration recommendation.

• Iron

  • Deficiency often arises from parasitism or chronic blood loss, leading to microcytic, hypochromic anemia.
  • Excess iron can disrupt copper metabolism, also causing anemia.

• Zinc

  • Deficiency in foals characterized by reduced growth, anorexia, skin lesions, and low alkaline phosphatase activity.
  • Excessive zinc (>1,000 ppm) linked to developmental orthopedic disease.

• Copper

  • Low blood copper levels may be associated with uterine artery rupture in older mares.
  • Deficiency can lead to aortic aneurysm and improper cartilage formation; excess can interfere with selenium and iron metabolism.

Thiamine

• Thiamine deficiency leads to anorexia, weight loss, incoordination, and elevated blood pyruvate, often seen in bracken fern poisoning.
• Natural diets generally provide sufficient thiamine, but stress may increase requirements.

Equine Nutritional Diseases

• Nutritional diseases can negatively impact horse performance and health.
• Categories include:
  • Directly related to nutrition: preventable with proper diets (e.g., Obesity, White Muscle Disease).
  • Indirectly related to nutrition: management through nutrition but not preventable (e.g., HYPP, Insulin Resistance).
  • Combination diseases: involve both direct and indirect factors (e.g., Laminitis, Equine Colic).

Diseases Directly Related to Nutrition

• Obesity
• White Muscle Disease
• Developmental Orthopedic Disease
• Mycotoxicosis
• Nutritional Secondary Hyperparathyroidism (NSH)

Diseases Indirectly Related to Nutrition

• HYPP
• Insulin Resistance
• Enterolithiasis
• Polysaccharide Storage Myopathy (PSSM or EPSM)

Combination Diseases

• Laminitis
• Equine Colic
• Equine Gastric Ulcer Syndrome (Equine Ulcers)

This quiz covers the nutritional deficiencies related to selenium and vitamins in horses. It explores the effects of selenium deficiency such as increased AST activity and risks associated with excess intake. Additionally, it addresses vitamin A deficiency and its implications when inadequate roughage is fed.