What is Exercise Induced Collapse (EIC)?
Dogs affected with EIC can tolerate mild to moderate exercise, but 5 to 20 minutes of strenuous exercise with extreme excitement induces weakness and then collapse. Severely affected dogs may collapse whenever they are exercised to this extend – other dogs only exhibit collapse episodes sporadically. The first thing noted during an episode is usually a rocking or forced gait. The rear limbs then become weak and unable to support weight. Many affected dogs will continue to run while dragging their back legs. Some of the dogs appear to be uncoordinated, especially in the rear limbs, with a wide-based, long, loose stride rather than the sort stiff strides typically associated with muscle weakness. In some dogs the rear limb collapse progresses to forelimb weakness and occasionally to a total inability to move. Some dogs appear to have a loss of balance and may fall over, particularly as they recover from complete collapse. Most collapsed dogs are totally conscious and alert, still trying
Episodes of exercise intolerance and collapse have been observed among Labrador Retrievers for many years, although the root cause was not always well understood. Dogs clinically affected by Exercise Induced Collapse (EIC) will often begin to exhibit leg weakness followed by a complete collapse after just 5 to 15 minutes of strenuous activity. The severity and duration of these spells can vary depending on the environment. EIC is a big problem particularly with hunting and field trial dogs, where long periods of excitement and exercise are common. In extreme cases, dogs affected by EIC can die. A genetic mutation that causes EIC has recently been identified, and it is estimated that at least 25% of all the Labrador Retrievers taking part in field trials today have at least one copy of the mutation. It is a recessive disorder; therefore carriers (those having 1 copy of mutation) will not show symptoms—however, if they are used for breeding, they will pass on the mutation 50% of the time
