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The Genetics of Exercise Induced Collapse (EIC)

Exercise Induce Collapse (EIC) is a condition most often seen in field trial Labrador Retrievers. However, the gene responsible for this disease has also been found in Chesapeake Bay Retrievers, Curly-Coated Retrievers, Boykin Spaniels, German Wirehaired Pointers, Old English Sheepdogs, Bouviers des Flandres, and Pembroke Welsh Corgis.

Symptoms

The symptoms of EIC tend to develop within five to twenty minutes of intense exercise combined with a high level of excitement. The excitement is an important component of a collapse. Affected dogs can do exercises that do not cause as much excitement for much longer without developing any signs of weakness or collapse.

Affected dogs will begin to appear wobbly, they may stagger, lose co-ordination and balance particularly in the rear. Although the dog may try to continue, it is very important that all exercise be stopped immediately at the first sign of symptoms. Allowing the dog to continue can lead to a fatal collapse. Some Labradors will appear to be disoriented and confused during an EIC attack while others will seem to be completely alert and cognizant. Symptoms may continue to worsen for up to five minutes after cessation of exercise. Recovery can take up to a half an hour.

Inheritance & Frequency Within the Gene Pool

Studies have shown that as many as 40% of Labrador Retrievers are carriers of the EIC gene. It is not more common in a particular color or sex of dog although it does seem to be more common in field trial lines. Because it is such a common gene, never breeding a carrier is not practical. However, breeders can make use of the gene test to ensure that they only produce clear or carrier dogs rather than affected dogs.

The disease is inherited by an autosomal recessive gene mechanism. This means that the disease is controlled by a single pair of genes, one of which comes from each parent. In genetics, the capital letter (E) indicates a gene clear of EIC. This is the dominant gene. A small letter (e) is the carrier gene and it is recessive. To have the disease, a dog must have the ee genotype, which means that he inherited one carrier gene from each parent. A dog with the Ee genotype does not have the disease and will never develop the disease, however he is a carrier of EIC and can pass it on to his offspring and produce affected puppies if bred to another carrier. A Labrador with the EE genotype does not have the disease will never develop the disease and cannot produce affected offspring. However, he can produce carrier offspring if bred to a carrier or affected dog.

Implications

Because Labrador Retriever breeders have access to a gene test for EIC, there is no excuse for producing an affected puppy. Although dogs with EIC can live long and normal lives, they have to give up all exercises that may cause a collapse. Since hunting and retrieving tend to produce a high level of excitement as well as provide intense exercise for Labs, these activities tend to be on the list of things an affected dog can no longer do. For some looking for a hunting dog as well as a family companion, this can be an extreme disappointment.

People interested in purchasing a Labrador, whether they wish to hunt with it or not, should discuss EIC with the breeders they consider buying their puppy from. Ask if they make use of the test and the results of the parents' tests. The breeder should be able to provide a certificate proving that the dogs have been tested and giving the results of the test. Do not take a breeders word for it, they should be able to provide a certificate and be willing to discuss the disease with you. Run from any breeder who says there is no need to test their breeding stock because they don’t have a problem. That is a breeder who is sticking their head into the sand about the disease. Buy smart so that you get a dog that will be able to do all the fun activities with you that you want to share with your Labrador Retriever.

Photo credit: bfarrell/deviantart.com

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