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Exercise-induced Collapse

Exercise-induced collapse (EIC) is a genetic condition characterized by episodes of ataxia and collapse after 5 to 15 minutes of strenuous exercise and excitement. Many times, dogs recover within about 30 minutes, but sometimes these events can be fatal.

The syndrome was initially discovered in Labrador Retrievers used for field trials and hunting, but ongoing research has shown that pet dogs and show dogs are just as likely to be affected1.

Prior to an episode, dogs with EIC appear normal and healthy. Based on a result for increased risk of EIC, lifestyle adjustments can be made to help avoid a fatal event.

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Breeds Affected

EIC was first found in Labrador Retrievers but since has been observed in other several breeds of retrieving, hunting or herding dogs.

EIC has been diagnosed in the following breeds:

  • Labrador Retrievers
  • Curly Coated Retrievers
  • Chesapeake Bay Retrievers
  • Boykin Spaniels
  • German Wire-haired Pointers
  • Old English Sheepdog
  • Cocker Spaniels
  • Pembroke Welsh Corgis

How common is EIC?

  • Up to 14% of Labs are affected (increased risk).
  • Prevalence of EIC in other breeds1
  • Dogs at risk for EIC due to a homozygous mutation are likely to encounter an episode of collapse between 5 months and 5 years of age.

>80% of affected Labradors experience at least one episode of EIC by the time they are 4 years

What does an EIC episode look like??

Video - https://www.youtube.com/watch?v=y8Uq8NFaYqM

 
Excitement/strenuous exercise

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Dog starts to stagger and become ataxic or appear uncoordinated.

  1. Hind legs become weak, but often the dog will try to continue running.
  2. Occasionally forelimbs can be affected as well resulting in complete collapse
 
Muscles will be relatively flaccid, and palpation of muscles, joints and spine is non-painful

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Typically, dogs are alert throughout the episode, but may also appear disoriented
 
Episodes typically last 5 to 10 minutes with complete recovery in 30 minutes

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Prevention & Treatment

What do I do if dog is at risk?

  • Lifestyle – hunting, field trials or other activities that induce extreme excitement or involve prolonged exercise are not recommended. These dogs will still make good pets.
  • Be very careful about outdoor activities in hot weather.
  • Recommend owner monitor their dog very closely.
  • Phenobarbital can be a treatment option if alternative lifestyle is not an option, but the mechanism and effectiveness are not well proven.

What to do if an episode occurs?

  • Make sure breathing is unobstructed.
  • Offer water or ice orally.
  • Help to cool the dog with water.
  • Force the dog to rest until fully recovered.
  • Occasionally episodes can be fatal – stop exercise at first sign of EIC!

Test Limitations

  • Collapse may occur due to other conditions including orthopedic disorders, heart failure, anemia, heart rhythm disturbances, respiratory problems, low blood sugar, cauda equina syndrome, myasthenia gravis, hypoadrenocorticism and muscle disease.
  • Managing common causes of collapse or syncope

Science and Genetics

Exercise-induced Collapse was first discovered in Labrador Retrievers in 2008.2 The disorder was then linked to a missense mutation in the dynamin 1 (DNM1) gene.3 The mutation is a G to T substitution in exon 6 of chromosome 9, which changes the amino acid codon from arginine to leucine.

Mode of Inheritance: Exercise-induced collapse is inherited as an autosomal recessive trait. Only dogs that are homozygous/affected for the genetic mutation are at increased risk. Carriers are not at an increased risk for collapse but could pass on the risk allele to their offspring.
Genotype Phenotype
No variant detected No increased risk based on the variant tested
CARRIER: 1 copy of the risk allele detected in the DNM1 gene No increased risk based on the variant tested
AFFECTED:2 copies of the risk allele detected in the DNM1 gene Increased risk for episodes of Exercise-induced Collapse

About the DNM1 gene: Dynamin-1 is a protein expressed in the brain and spinal cord. During times of excitement, the DNM1 protein plays an important role in transmission between nerve synapses in the brain and spinal cord.

References

  1. https://www.vetmed.umn.edu/research/labs/canine-genetics-lab/genetic-testing/exercise-induced-collapse
  2. Taylor, SM., Shmon, CL., Shelton, GD., Patterson, EN., Minor, K., Mickelson, JR. Exercise-induced collapse of Labrador retrievers: survey results and preliminary investigation of heritability. J Am Anim Hosp Assoc 44:295-301, 2008. Pubmed reference: 18981194.
  3. Patterson, E. E., Minor, K. M., Tchernatynskaia, A. V., Taylor, S. M., Shelton, G. D., Ekenstedt, K. J., & Mickelson, J. R. (2008). A canine DNM1 mutation is highly associated with the syndrome of exercise-induced collapse. Nature Genetics, 40(10), 1235–1239. https://doi.org/10.1038/ng.224