I was recently at the center for blood donation, as I must give monthly to regulate a genetic liver disease where my organs store too much iron. The disease, hemochromotosis, has been around forever but doctors never knew to look for it and then began to associate it with men only when they presented with symptoms of heart disease. My dad has it and I remember his occasional liver biopsies and his giving blood all the time but actually about ten years ago, a family doctor suspected something with me after reviewing a common blood panel she had run and sent me to a liver specialist. My liver biopsy showed 2.4 times the severe level of iron in my organs at that time which leads to organ cancer eventually if not prevented from worsening with the blood donations.

There I saw a couple I hadn't seen for years here; I used to work with the wife. They asked if I still had dogs...... and then he began to share about a dog he had bought for companion-hunting about two years ago. He began to describe that when she would retriever bumpers in the yard in training for hunting season as well, four times last year as they were hunting pheasants, she would look funny in the rear and wobble. She seemed uncoordinated and he watched in horror as her rear end collapsed and she fell over. He bought her from a 'breeder' who had been breeding for years and the parents were OFA certified for hips and elbows; he remembered that was important from our discussions in the 1980's.

He didn't know what to do about this and the two vets that had seen her had no idea but guessed some sort of seizure disorder. His hunting is done in rather warm climate and she ran hard in the alfalfa fields looking for birds. We then talked about EIC. His wife whispered to me, “Diann, he's really upset because he bought her, from 'a breeder', asked all about OFA and tried hard to get us a great family dog and one to train for hunting... He doesn't know what to do.”

This problem called 'Exercise Intolerance and Collapse' is being experienced with increasing frequency in Labrador Retrievers. It first presents between five months of age and three years with the average age being about fourteen months. All three colors and of both sexes are affected. Originally, black males from field trial breedings were the majority of cases but now, more-and-more dogs with 'show backgrounds' are also showing up affected. One common denominator among dogs showing symptoms is also that they are fit, muscular, athletic and have temperaments with drive.

For these dogs, mild or moderate exercise (5 to 15 minutes), is just fine but then continued exercise that is strenuous and that is also exciting for the dogs, brings about a gait that seems forced, the rear legs look to be weak and are often dragged, and many collapse. Some dogs try really hard to continue running but drag their back legs. Some dogs do not require as much exercise as others and some may collapse during any activity they find exciting or stressful such as retrieving birds, activities such as fly ball or training drills, while others can develop symptoms while only playing fetch, when quartering in a field while hunting for upland game and even running along a bicycle or ATV.

There are factors associated with bringing on a collapse – IF the temperature of the environment is more humid and hotter than the dog is used to, collapse may be more likely BUT, temperature itself has not been seen as a general contributing factor. There does seem to be a link between actual collapse and the dog having a driven temperament type and symptoms can be triggered by exciting activities like retrieving live birds, electric collar stress or hunting game. BODY TEMPERATURE is an interesting factor in collapse as these dogs have normal at-rest temperatures but, at the time of collapse, their body temperatures rise dramatically to 107-108 degrees ! Veterinarians and researchers believe that then CONTINUOUS EXERCISE IS also a factor in collapse.

Veterinary examinations of dogs affected show that cardiovascular and musculoskeletal examinations as well as routine blood work is NOT remarkable. The dogs that have collapsed show only reduced or no knee reflexes at time of collapse but this symptom disappears after 10-30 minutes. The collapsed dog does not have irregular heart rhythms, low blood sugar, imbalances in their electrolytes or breathing difficulty. Recovery from collapse is very quick and dogs appear normal within 5 to 20 minutes with no remaining weakness or stiffness.

In having a dog in an unusually hotter environment than usual, one might think the symptoms are heat stroke but with heat stroke, recovery is very slow that can take hours to days and may even lead to death. EIC collapse or symptoms are completely gone with a happy dogs running around in 5 to 25 minutes.

Epilepsy, which is present in our Labradors, does have an unusual form that shows itself as a very sudden onset with a very sudden resolution of symptoms. EIC symptoms and collapse occur gradually and the presence of weakness, lack of coordination and collapse, also disappear over minutes to a half-hour.

IF your dog collapses, what do you do ????? First, make sure that the dog can breathe freely so that it can blow off body heat. Offer your dog small amounts of water or ice orally and, cool the dog by laying wet towels over him or wetting him down. You must make sure he stays resting until fully recovered.

Treatment ? A collapsing Labrador retriever should have blood testing done to confirm that it is indeed AFFECTED with EIC (has two genes for the disease). The 'treatment' for dogs affected with EIC involves ending training and exercise at the first sign of weakness. The old stand-by drug for seizures, PHENOBARBITAL, twice a day and every day given only by a veterinarian's supervision has allowed some dogs to continue training or competition.

Every trait that makes dogs who they are has a genetic basis whether it be for fabulous coat, retriever drive or defects. My high-iron absorption disease can be serious indeed and there is no cure. The genetic marker test is extremely expensive with very few physicians even knowing about the disease. It is passed on to children by one affected gene from the one parent and with another normal gene from the other parent. THE SAME WAY THAT EIC IS ALSO PASSED ONTO OUR LABRADOR PUPPIES. Littermates and other related dogs are commonly affected.

For over ten years, major studies of Exercise Induced Collapse has been researched. Sadly, not knowing what this was in otherwise healthy dogs has been confusing for almost twenty years. Researcher James Mickelson, PHD., professor of veterinary medicine at the University of Minnesota together with Susan Taylor, D.V.M.,DACVIM, of the Western College of Veterinary Medicine at the University of Saskatchewan have conducted a genome scan to identify the location of the gene and published the research last October in Nature Genetics. EIC is inherited as a non sex-linked recessive meaning, that affected dogs receive one gene for the disease from a parent who is a 'carrier' and one gene from the other parent that is normal. Research shows that 80% of affected dogs had signs of EIC and at least one collapse.

Testing for EIC through the University of Minnesota is very easy and inexpensive. Interpretation is that dogs determined to be CLEAR= The dog has two copies of the NORMAL gene, doesn't not have the disease nor will produce the disease. CARRIER= The dog does not have the disease BUT has one normal gene and one mutated gene associated with the disease. Should this dog breed to another 'carrier' of the EIC gene, a percentage of the puppies will be carriers also (approximately 25%), BUT up to 50% will be affected !

Breeders sell the majority of their puppies to companion homes and many of those new owners dreamed for a long time to train their puppy to hunt or to participate in agility, field work, etc. Dogs who develop symptoms for EIC are rarely able to continue training or competition. They live often normal pet lives if their owners are willing to limit their exercise or excitement. Most of those I know don't realize that affected dogs have died, either because an episode happened in the water and they drowned or, simply during the exercise itself. Symptoms increase often minutes AFTER the exercise has been stopped.

Continued studies of the genetics behind this disease is ongoing and yet a test is available NOW for diagnosis and selection of breeding animals. We must care about limiting the production of affected dogs.

REFERENCES

Fawver, Barbara., editor, Purina Todays Breeder: New Frontiers in Genetics

Taylor,SM, Mickelson JR. Evaluations of Labrador Retrievers with Exercise Induced Collapse. Journal of the American Animal Hospital Assoc. January 2009