EIC appears to be autosomal recessive in inheritance, but is unique in that the clinical signs are environmentally induced in dogs homozygous for the mutation. Affected dogs appear normal, and are capable of moderate exercise without incident. However, shortly after any strenuous exercise or excitement, they develop a wobbly gait with hindlimb weakness and incoordination, wide based stance, and walking with crouched hind legs. Signs can progress to full body weakness, extensor rigidity, and confusion. In extreme cases, it has been reported as fatal. Research indicates that the d-EIC mutation for this test may be particularly important to Labrador retrievers concerned about EIC, based on the N. American and European dog populations in the study. A number of hunting/retrieving breeds have been investigated, with phenotype confirmed in some, and suspected in additional breeds. In addition, there are likely other, unrelated causes of excercise intollerance and collapse. Breeds where phenotype and mutation has been established: Labrador Retrievers (and their crosses), Chesapeake Bay Retrievers, Curly-coated Retrievers, Boykin Spaniels, Pembroke Welsh Corgi. Breeds where the mutation has been detected: American Cocker Spaniel, Bouvier des Flanders, Clumber Spaniel, English Cocker Spaniel, German Wirehaired Pointer, Old English Sheepdog, Hungarian Shorthaired Vizsla, Hungarian Wirehaired Vizsla.