Vitamin E / Selenium
Vitamin E and Selenium are frequently utilized together due to their synergistic antioxidant properties, though Vitamin E is also widely used as a standalone supplement. - **Vitamin E (Alpha-tocopherol)** is a lipid-soluble vitamin essential for protecting cell membranes from oxidative damage. It is used adjunctively for various dermatologic (discoid lupus, demodicosis), hepatic, and neurologic conditions. - **Selenium** is a trace mineral that acts as a crucial cofactor for antioxidant enzymes. Combination products are primarily indicated for the treatment or prophylaxis of **selenium-tocopherol deficiency (STD)** syndromes, such as white muscle disease in livestock. > **Clinical Pearl:** While Vitamin E has a wide margin of safety, **Selenium is highly toxic** in overdose. Combination products must be dosed meticulously based on the selenium concentration and should only be used in FDA-approved species.
Mechanism: Both Vitamin E and Selenium are intricately involved in the cellular metabolism of sulfur and the prevention of oxidative stress. - **Vitamin E** acts as a potent biological free radical scavenger. It prevents the oxidation of polyunsaturated fatty acids within cellular and subcellular membranes. - **Selenium** is an essential structural component of the enzyme **glutathione peroxidase** โ this enzyme catalyzes the reduction of lipid hydroperoxides to their corresponding alcohols, neutralizing their potential to cause cellular damage. Together, they protect against red blood cell hemolysis and prevent the destructive action of peroxidase on unsaturated bonds in cell membranes.
Dosing by species
- Vitamin E/Selenium deficiency (using Bo-Se) ยท Lambs (2 weeks of age or older): 1 mL per 40 lbs. body weight IM or SC (1 mL minimum). Ewes: 2.5 mL/100 lbs. body weight IM or SC. ยท IM/SC ยท Single dose ยท Slaughter withdrawal = 14 days.
- Vitamin E/Selenium deficiency (using L-Se) ยท Lambs: 1 mL SC or IM in newborns and 4 mL SC or IM in lambs 2 weeks of age or older ยท SC/IM ยท Single dose ยท Slaughter withdrawal = 14 days.
- Treatment of tocopherol deficiency associated with exocrine pancreatic disease ยท 30 Units PO once daily for one month then every 1-2 weeks as needed ยท PO ยท q24h ยท 1 month, then q1-2 weeks
- Adjunctive treatment of hepatic lipidosis ยท 10 Units/kg once PO once daily ยท PO ยท q24h
- Vitamin E/Selenium deficiency (using Mu-Se) ยท For weanling calves: 1 mL per 200 lbs. body weight IM or SC. For breeding beef cows: 1 mL per 200 lbs. body weight during middle third of pregnancy and 30 days before calving IM or SC. ยท IM/SC ยท Variable ยท Slaughter withdrawal = 30 days.
- Vitamin E/Selenium deficiency (using Bo-Se) ยท Calves: 2.5-3.75 mL/100 lbs body weight (depending on severity of condition and geographical area) IM or SC. ยท IM/SC ยท Single dose ยท Slaughter withdrawal = 30 days.
- Adjunctive treatment of ionophore (monensin) toxicity ยท 4-12 Units/kg PO once daily ยท PO ยท q24h
Routes of administration
Contraindications
- Use of combination products in non-FDA approved species
- Use of Bo-Se in newborn pigs
Adverse effects
- Anaphylactoid reactions
- Transient muscle soreness at injection sites (IM)
- Selenium toxicity (depression, ataxia, dyspnea, blindness, diarrhea, muscle weakness, garlic breath)
Drug interactions
- Iron ยท Large doses of vitamin E may delay the hematologic response to iron therapy in patients with iron deficiency anemia.
- Mineral oil ยท May reduce the absorption of orally administered vitamin E.
- Vitamin A ยท Absorption, utilization, and storage may be enhanced by vitamin E.
- Warfarin ยท Vitamin E may increase the effects of warfarin.
Monitoring
- Clinical efficacy
- Blood selenium levels (when using combination products)
- Glutathione peroxidase activity (optional)
Overdose
Selenium is quite toxic in overdose quantities, but has a fairly wide safety margin. Cattle have tolerated chronic doses of 0.6 mg/kg/day with no adverse effects (approximate therapeutic dose is 0.06 mg/kg). **Clinical signs of selenium toxicity include:** - Depression, ataxia, dyspnea, blindness, diarrhea, muscle weakness - A distinct **'garlic' odor** on the breath - **Horses:** May become blind, paralyzed, slough their hooves, and lose hair from the tail and mane. - **Dogs:** May exhibit anorexia, vomiting, and diarrhea at high dosages. Large overdoses of **vitamin E** alone can cause coagulopathies.
VetSheet drug reference is intended for licensed veterinary professionals as a clinical decision-support aid, not a substitute for professional judgement or the manufacturerโs current label.