SCID is a lethal disease of Arabian foals inherited as an autosomal recessive. Lacking a competent immune system, SCID foals succumb before five months of age to massive infection, primarily of the respiratory tract. An affected foal provides evidence of carrier status of both parents. A DNA test is now available.

This is a condition of the nervous system that ranges from a lack of coordination of voluntary muscular movements to the paralysis of both front and rear legs. Vertebrae fuse together in the neck and fuse to the base of the skull as well. Foals often cannot stand to nurse or the symptoms may not be seen for several weeks.

Degeneration of the granular layer of the cerebellum portion of the brain causes a lack of coordination, a lack of balance and head tremors. Symptoms generally do not occur until the foal is several weeks old. The gait (movements) become exaggerated and the legs are placed wide-apart to stand at rest. Early indications include crashing into fences and falling over backwards.

Brain lesions cause behavior that is frequently consistent to when the brain is denied oxygen a birth. Foals are often the result of a difficult birth, are unable to stand and nurse, have rigidity in their joints and may have rapid eye movements. Coat color is a dull gray and the skin tends to be an unhealthy pink color; hence, lavender. These foals die.