Dr. Mark is a veterinarian. He works mostly with dogs and exotic animals.
If you have noticed that your Lab is no longer able to run after a ball or retrieve during a hunt, it might not just be age. All sorts of diseases can cause a dog to collapse during exercise, including a genetic disorder called exercise-induced collapse (EIC).
Labs that seem healthy can have EIC and it is not even noticed until the dog is about 14 months to 3 years old and the dog has an episode. It is caused by a mutation in dynamin-1 (an enzyme that helps nerves work normally) and starts with the dog wobbling while running but can then lead to full collapse. Some studies report that up to 40% of Labs are carriers and maybe about 5% are homozygous for this defect and start developing problems as they age.
Symptoms of Dogs With Exercise-Induced Collapse
- Ataxia (especially clumsy when running)
- Rear legs weak, sometimes dragged when experiencing an episode
- Unable to come when called
- Higher than normal body temperatures after exercise
- Fast breathing
- Recovery from collapse after about 10 to 20 minutes, although some dogs can die after a severe episode.
Dog Breeds Affected With Exercise-Induced Collapse
- Labrador Retrievers
- Curly Coated Retrievers
- Chesapeake Bay Retrivers
- American Cocker Spaniels
- English Cocker Spaniels
- Clumber Spaniels
- Boykin Spaniels
- Bouvier des Flanders
- German Wirehaired Pointers
- Old English Sheepdogs
- Pembroke Welsh Corgis
- Crossbreds of any of these dog breeds (if both parents carry the gene for EIC)
There may be other breeds found to be affected in the future. Some other dog breeds (Border Collies, Australian Cattle Dogs, Whippets, and some others) have a type of exercise intolerance that is not caused by the same gene. There is still no way to test for this problem in these dog breeds and no treatment exists.
Other Reasons a Dog can Collapse During Exercise
Dogs can have seizures when out playing ball or hunting and unless it has been seen before most people report a collapse. (If you have your cell phone with you when your dog collapses try to take a video so that you can show your vet later when your dog is being examined.) Epilepsy is common in Labs and happens a lot when they are excited during exercise. It is not always easy to diagnose, so any dog that collapses is a suspect for epilepsy.
Hip Dysplasia and Other Orthopedic Diseases
Dogs with hip dysplasia are not always lame and sometimes just show up with an abnormal gait in the back legs when running. They may be stiff later and reluctant to run again but no other signs are seen until arthritis develops later. Younger dogs can also have panosteitis, hypertrophic osteopathy, or even bone cancer, all of which will cause reluctance to exercise.
Almost everyone has seen an overweight Lab and sometimes the reason they will not exercise is not a genetic disease, just poor condition. If your dog is overweight and collapses during exercise the first thing to do after an examination is to start a weight control program. Obese dogs can be suffering from hip problems and airway diseases, so be sure to have them examined by your vet before starting them up on a strenuous exercise program.
Any dog with obesity, exercise intolerance, and skin disease should be a suspect for hypothyroidism. The thyroid hormone levels in the blood should be tested in all Labs with exercise intolerance, even those without hair loss or other skin diseases.
Low Blood Sugar
Some dogs will get weak and might even collapse because of low blood sugar. They are usually thin pointers and spaniels so EIC needs to be ruled out. Young hunting dogs with low blood sugar may have an inherited disease but it is treatable once the disease has been identified.
Dogs with anemia will probably not collapse but will be reluctant to exercise if the amount of red blood cells in the blood falls very low, usually less than 20%. The condition may or may not be life-threatening, depending on the cause, so any dog reluctant to exercise needs an examination and blood testing by a veterinarian.
Most dogs with heart disease, even young pets that have congenital heart disease, show signs of heart failure and not just exercise intolerance. Many others can be picked up on the physical exam, but even if it is not, most veterinarians will suggest x-rays and an EKG to rule out heart disease.
If there are any abnormalities in the respiratory tract dogs can show signs of exercise intolerance and collapse. Some of the problems can be diagnosed during the exam and with x-rays, but others might require your dog to be examined with an endoscope.
There are several inherited muscle diseases that have to be ruled out in young Labs that collapse. Some of them, like muscular dystrophy and centronuclear myopathy, are easy to differentiate from EIC during the exam because the muscles are wasted. Others just cause muscle weakness during exercise and will require muscle biopsy and sometimes even genetic testing.
Dogs with hypoadrenocorticism usually show up with poor appetite, depression, and vomiting but about 10% of the dogs will show up after collapsing during exercise. The collapse may be due to low blood sugar but the disease is caused by a deficiency of cortisol in the body, which can be tested for before and after stimulation.
Other diseases may be discovered in the future but most of them, like polyneuropathies and many muscle and neurological diseases, have other symptoms that allow them to be diagnosed during the exam.
Diagnosing a Dog After Collapse
If your dog collapses during exercise take them in for an examination as soon as possible so all of the possible problems can be ruled out. The vet will ask about how this happened and if you have a video of the collapse it can be very helpful and save time; some tests can even be avoided.
The examination may be normal, and if no symptoms are found the following tests will be run:
- X-ray to examine joints, heart, throat, and lungs
- EKG and ultrasound to check the heart
- Endoscopic exam of the larynx if the laryngoscope was not sufficient
- Blood test to check the thyroid, red blood cell levels, and internal organs
- Blood sugar measured during exercise
- Muscle biopsy (will require anesthesia)
- Cheek swab or blood test to check the DNA. (Dogs with EIC have two copies of the mutated gene, one from each parent, so if you still are in contact with your dog´s breeder be sure to let them know about the results of the test.)
How to Help a Dog With Exercise-Induced Collapse
I have read of one anecdotal report of CBD oil helping a dog with EIA, but this does not make any sense. (Like phenobarbital, which one university reported as helping in some cases, it may just have made the dog less excited and more prone to avoiding excessive exercise.) Some intact male dogs might benefit from neutering. The disease is genetic and unless a gene-splicing therapy is developed in the future there is not much that can be done for these dogs.
The best way to help your dog is to avoid the situations that trigger the attacks.
Do not take your dog out to run and exercise excessively, especially when it is hot. Keep your dog thin, and make sure that any other problems, like arthritis secondary to hip dysplasia, are treated so that they have to deal with as few things as possible.
If you have noticed that your dog is weak or running abnormally, be sure to have him or her checked out by your veterinarian. If no other disease is found during the examination and testing, he or she can do the genetic testing for EIC or they will help you find out where it can be sent.
This short video shows one dog with the abnormal gait seen in some dogs with exercise induced collapse. Others might just stand still and be too weak to move around while others will fall over in full collapse.
This demontrates what can happen to a dog that is not severely affected.
This Lab owner chose to continue to call her sick dog even as he became weak and the dog eventually collapsed. The video she made is a good illustration of why it is best to just leave a dog suffering from EIC in peace. (Researchers report that this condition is not painful but a dog in collapse is certainly uncomfortable.)
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This article is accurate and true to the best of the author’s knowledge. It is not meant to substitute for diagnosis, prognosis, treatment, prescription, or formal and individualized advice from a veterinary medical professional. Animals exhibiting signs and symptoms of distress should be seen by a veterinarian immediately.