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Exercise Induced Weakness and Collapse in Labrador Retrievers

Labrador retrievers are one of the more active dog breeds. Part of having a Lab in your family is to become accustomed to having a high energy dog that plays and exercises a lot. Most dogs will slow down or stop when they are tired and will have no problems, but some revel so much in activity that they will exercise until they become weak and collapse from exhaustion. This is called exercise induced collapse in Labrador retrievers. Problems usually occur during periods of intense activity or excitement. At other times, these dogs seem completely normal.

Symptoms are first seen in young dogs between five months of age and three years of age. The disease does not seem to affect one gender more than the other. Labs bred to be field trial dogs may be more likely to have the problem, and Labs that are easily excited are more likely to have the problem. Collapse is most likely to occur when the temperature and humidity are high, and during activities like upland bird hunting, repetitive retrieving, long, hard running, and intense play, but any very intense activity can lead to collapse.

Symptoms and Types

Signs begin after five to twenty minutes of extreme exercise, excitement, or stress. They include:

• Not walking or running normally (rocking gait)
• Weak back legs
• Dragging the back legs while running
• Standing with the feet too far apart (wide-based stance)
• Picking the feet up too far while walking or running (hypermetria)
• Falling over while running
• Unable to move the head and all four legs after exercise
• Stiff front legs while collapsed
• Most dogs are alert
• No pain while collapsed
• High body temperature
• Occasionally, confusion
• Rarely, seizures and death
• No symptoms between times of collapse
• Recovery usually within five to twenty five minutes

Causes

An inherited problem in Labrador retrievers that is an autosomal recessive trait. Dogs that carry two copies of the gene (homozygotes) are at substantial risk of showing clinical signs. Dogs that carry one copy of the gene (heterozygotes) are carriers and can pass the gene to their puppies. However, they are not likely to show symptoms of exercise induced collapse.

Diagnosis

A genetic test is available to identify the gene that causes exercise induced collapse in Labrador retrievers. If your veterinarian suspects this disease, the genetic test may be recommended to confirm the diagnosis.

Other testing your veterinarian may want to perform includes a complete blood count and biochemical profile. These will confirm that your dog's internal organs are working properly. Your dog's thyroid hormone level may also be checked to make sure it is normal. Other blood tests can be analyzed to see if other muscle diseases might be causing your dog to collapse. To make sure that your dog is not suffering from a heart problem that comes and goes, your veterinarian may want your dog to wear a special monitor for a day or two to track normal heart rhythm. These tests are typically normal in Labs with exercise induced collapse.