Shedding

Several weeks prior to shedding, an iguana's skin may appear dull and take on a gray or yellowish-gray cast. Unlike snakes, iguanas, and other lizards do not shed the skin over their entire surface at one time. White patches will appear where the skin loosens, just prior to being shed.

Disease Conditions

Iguanas with liver disease may appear yellow, especially their mucous membranes. This yellow color should not be confused with the yellow cast that may appear prior to shedding.

Red mite infestations may cause some scales on the skin to become raised and black. These are generally found on the ventral abdomen (belly) and limbs, and should not be confused with the normal striping or reticulated pattern. Darker raised areas can also be a result of fungal infections.

The skin over injuries will usually appear pink, smooth, and scaleless. Burns often appear black. With each shed, the affected area will become smaller. The new scales may be smaller and darker in color than neighboring scales.

Bacterial infections of the skin, often termed "blister disease," "scale rot," or "vesicular dermatitis," can at first cause blisters of the skin, and then turn the skin a dark brown to black color. These infections are usually due to poor cage hygiene or too moist an environment. This disease can be fatal.

Heavy parasite infestations, gastrointestinal obstructions or constipation, malnutrition, and other chronic diseases can cause an iguana to become mustard yellow to dark brown or almost black in color. These color changes generally affect the body and head first, then extend to the limbs and tail.

These color changes can also occur due to other stressors such as:

• Poor environment (wrong temperature, humidity, photoperiod, inadequate enclosure, poor hygiene)
• Fear resulting from a dominant cage mate, household pet, or person
• Changes in household routine such as what may occur with moving, addition of new pets or a baby, holiday festivities, or long absences

Summary

Any color changes in your iguana, not related to breeding season or shedding, are an indication that your iguana may be ill and should be examined by a veterinarian.