EIC is a genetically based syndrome associated with high temperatures and humidity. The mutation is seen in 5 to 10 percent of dogs of certain breeds, especially Labrador retrievers.
Katie Minor, a scientist with the University of Minnesota Canine Genetics Lab, which discovered the mutation, says, “Typically the first sign of EIC is wobbliness in the rear limbs. If you don’t stop the dog, they can lose balance and the legs can become temporarily paralyzed. Usually they recover in about a half-hour, but if they’re not stopped they can die. Once thought to be ‘hunting dog hypoglycemia’ or dogs that were heat-intolerant, EIC is now preventable through genetic testing and planned matings.”
Older dogs are more susceptible than others to heat. One reason is that they are more apt to develop laryngeal paralysis, a common upper respiratory disease involving narrowed airways and nerve degeneration. This condition is most common among Labrador and golden retrievers. Symptoms include harsh breathing, coughing, gagging and hoarse voice.
“Laryngeal paralysis can be life-threatening because dogs cannot move air in and out of the lungs normally, as they do through panting,” explains Kurt S. Schulz, a veterinarian with Peak Veterinary Referral Center in Williston, Vt. “The condition means they can’t get enough air, and the harder they try, the more difficult it becomes. The result can be severe or fatal stroke.”
Laryngeal paralysis can be treated surgically, preferably before the weather gets too warm, by opening the airway passages.