Background and history

Iron toxicity occurs when the sow and her piglets are deficient in vitamin E. Iron dextran injections become toxic and cause severe muscle reactions at the injection site.

Iron injections as iron dextran are given by intramuscular or subcutaneous injections to piglets between one and seven days of age. This is to correct the development of iron deficiency that leads to anaemia. A dose level of 100–200mg per piglet is required.

If sows or gilts become deficient in vitamin E and/or selenium during pregnancy, piglets are also born deficient. Under such circumstances the enzymes which metabolise the iron cannot function and the iron then becomes toxic.

Clinical signs

• Two to four hours after injection most of the litter become acutely lame on the legs that have received the iron.
• The affected muscles swell.
• The piglets develop heavy breathing and look pale.
• Anaemic apearence.
• Death occurs within 24 hours.
• A dark swelling occurs at the site of the injection (usually the thigh).
• At post-mortem the muscles are coagulated and appear like fish tissue due to necrosis of the muscle fibres.

Diagnosis

This is based on the clinical signs and knowledge of the timing of injections.

The association between injections and symptoms is usually clear and the clinical signs are typical.

Causes

• Vitamin E deficiency in the sow.
• Vitamin E deficiency in the sow occurs when fats in the diet become rancid or cereals or corn have fermented and spoiled and the vitamin E is destroyed. Piglets are then born deficient
• Poor quality iron dextran will predispose.

Prevention

• Clean out the cereals at the bottom of the storage bins.
• Excessive oxidation of fats in the sow feed is the most common cause of low vitamin E status. Oxidation results from poor storage of cereals or corn and particularly in situations where the bottoms of feeds bins are not cleaned out and moisture has gained access.
• Assess cereals and corn for spoilage.
• Check the sources and storage facilities of all feed grains.
• As a precaution add an extra 150im/tonne of vitamin E to the sow feed for the next two months.
• Inject sows due to farrow over the next 3 weeks with a vitamin E selenium preparation.
• Alternatively use water soluble vitamin E.
• Inject all litters for a 3 week period with vitamin E or dose by mouth at least 2 days before iron injections are given.
• Inferior quality iron dextrans (usually the cheap ones) are more likely to be associated with severe disease

Treatment

As soon as the condition is recognised all the piglets that have had iron within the last two days should be injected with vitamin E/selenium according to the manufacturers recommendations.