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Summary
Exercise Induced Collapse (EIC) is both a general term for what happens when animals succumb during or after extreme exercise and a disease we see in very fit Labrador retrievers. For the purposes of this article, it's the latter condition we'll tackle.
EIC was first identified in 1993, but since then, it's become an increasingly identified disease among Labrador retrievers. Because littermates and other related dogs were found to be similarly affected, the disease came to be understood as a recessive hereditary trait. It's since become clear that the exact source of the genetic problem involves a mutation in a gene involved in the communication between nerves of the central nervous system.
In EIC, dogs will collapse after 5 to 10 minutes of high-drive, trigger activities like chasing a ball or hunting. Though a large majority of these cases recover completely within a short time frame (under 30 minutes), many dogs have been known to die of this condition.
Symptoms and Identification
Dogs with Exercise Induced Collapse will display a wobbly gait after a few minutes of hard exercise. If the exercise continues, they will usually eventually collapse. High temperatures (over 107 degrees F) and flaccid muscles have been the historical hallmarks of this disease, though it's now been determined that many dogs of similar breeds experienced equivalent high temperatures for the same period of extreme exercise.
But not all affected dogs will collapse every time. High ambient temperatures and high excitement levels seem to factor into the symptoms and, hence, into identification of this disease through careful history-taking by a veterinarian.
The diagnosis is arrived at through this history of collapse during high-drive exercise, usually in excitable Labradors who are extremely fit and well-muscled. Dogs with this history may be diagnosed with a test now available at the University of Minnesota.
Affected Breeds
Labrador Retrievers of all colors have been found among the affected patients. "Field Lab" breeding lines have been flagged as producing the most likely candidates for EIC.
Treatment
The only treatment for Exercise Induced Collapse revolves around avoiding extreme exercise, particularly activities that most likely trigger the dog to enter high-drive mode. Dogs must be "retired" to the life of a quiet, indoor house-pet.
Though it's been postulated that phenobarbital (normally used as an anti-seizure medication in dogs) may be helpful, those who study this disorder have found that it merely limits the dogs' excitement levels and exercise drives by sedating them. It does not directly treat the problem.
Veterinary Cost
The cost of diagnosis is the largest expense owners will face. A veterinary visit, basic lab work and the cost of the genetic test is typically all that is considered strictly necessary in these cases. But not every dog's history of collapse will lead directly to the correct test.
Because the test is very new to the veterinary world and the disease is considered uncommon, dogs may still be put through their [expensive] diagnostic paces. Here's one example where seeing a specialist very early on in the diagnostic process may help prevent unnecessary testing.
Prevention
Prevention of EIC is achieved primarily by identifying affected dogs through clinical signs or testing and removing them from the breeding pool. Testing first and second degree relatives of those who show clinical signs or test positive is imperative. Further, testing of all field Labs is currently recommended prior to breeding. Prevention of individual events is undertaken by limiting behaviors that may trigger an episode.
References
Patterson EE, Minor KM, Tchernatynskaia AV, Taylor SM, Shelton GD, Ekenstedt KJ, Mickelson JR. A canine dynamin 1 mutation is highly associated with the syndrome of exercise-induced collapse. Nature Genetics 2008; 40(10): 1235-1239.
Taylor SM, Shmon CL, Adams VJ, Mickelson JR, Patterson EE, Shelton GD. Evaluations of Labrador Retrievers with Exercise Induced Collapse, including response to a standardized strenuous exercise protocol. Journal of the American Animal Hospital Association, January 2009.
Taylor SM, Shmon CL, Shelton GD, Patterson EE, Minor K, Mickelson JR. Exercise Induced Collapse of Labrador Retrievers: Survey results and preliminary investigation of heritability. Journal of the American Animal Hospital Association, November 2008; 44: 295-301.
Taylor SM. Exercise-induced Weakness/Collapse in Labrador Retrievers In LP Tilley and FW Smith (eds), 2008, Blackwell's Five Minute Veterinary Consult: Canine and Feline (4 th edition). 458-459.