Exercise-Induced Collapse (EIC) is an inherited neuromuscular disease that mainly affects the Labrador Retriever and other retriever breeds. It is characterised by episodes of muscle weakness and collapse that occur during or immediately after intense exercise and subside within a few minutes, with the dog normal between episodes.

Described in the Labrador Retriever and also in the Chesapeake Bay Retriever, Curly Coated Retriever, Boykin Spaniel and Pembroke Welsh Corgi. In a US population of 400 Labradors, ~37 % carriers and ~3 % homozygotes were found (Patterson et al., 2008).

- Progressive muscle weakness during or immediately after exercise
- Collapse with preserved consciousness (the dog is conscious but cannot move)
- Muscle tremors and ataxia
- Loss of patellar reflexes after the episode
- Recovery in 5-30 minutes
- Between episodes: completely normal behaviour
- Episodes recur with the same type of exercise

EIC was described clinically in the Labrador Retriever in the 1990s. In 2008, the group of Patterson and Mickelson identified, through linkage and association analysis on chromosome 9, the causal mutation in DNM1 (c.767G>T; p.Arg256Leu), which alters dynamin 1 and synaptic vesicle recycling.

- Test breeding dogs before mating
- Do not mate carrier × carrier: 25 % affected homozygotes
- A carrier can be mated to a clear dog; test the offspring intended for breeding
- Distinguish EIC status from other breed tests in the record
- Avoid the triggering intense exercise in affected animals

Differential diagnosis includes mitochondrial myopathies, hypoglycaemia, epilepsy and Border Collie collapse (of a different polygenic origin). The DNM1 genetic test is specific to retriever EIC; a negative result does not rule out other causes of collapse. There is no curative treatment: management is based on controlling exercise. The prognosis for quality of life is good if intense exercise is limited.

1. Patterson EE, et al. A canine DNM1 mutation is highly associated with the syndrome of exercise-induced collapse. Nat Genet. 2008;40(10):1235-1239. PMID: 18806795
2. Taylor SM, et al. Exercise-induced collapse of Labrador retrievers: survey results and preliminary investigation of heritability. J Am Anim Hosp Assoc. 2008;44(6):295-301. PMID: 18981194
3. Minor KM, et al. Presence and impact of the exercise-induced collapse associated DNM1 mutation in Labrador retrievers and other breeds. Vet J. 2011;189(2):214-219. PMID: 21782486
4. Furrow E, et al. Relationship between dynamin 1 mutation status and characteristics of recurrent episodes of exercise-induced collapse in Labrador retrievers. J Am Vet Med Assoc. 2013;242(6):786-791. PMID: 23445289