Ootoowak's Amaruq:   a great Inuit Sled Dog - "bear dog"; 
dam, granddam and greatgranddam to many fine working dogs.
                                                         Hamilton photo

At the Heart of Greatness

by Janice Dougherty

"At the Heart of Greatness" is the title of an article by Laurie Bonner in the November 2004 issue of Equus  magazine. There is also a companion article entitled "Great Heart" by Marianna Haun. Those who have read my articles in The Fan Hitch know that I have more than once used such "horse sense" as a jumping off point for my writings about dogs. Mammalian physiology, animals as athletes, genetics of performance and sports medicine all have many parallels between species, and I think the topic of heart size is one that might deserve some attention. But, as has been previously commented on by our editor, Sue Hamilton, I have no expectation that such research will ever be pursued in time (before there are no more true ISDs). However…

Humans are a visual species, and often very shortsighted at that.  We are inordinately impressed by what we see at the moment. With the power of image over the real, underlying substance will always be a problem with us. It is why the plain horse Seabiscuit's legendary victory over the glamorous War Admiral was such a stunning knockout. We have a harder time appreciating that which is not overtly visually apparent. A past article in Equus discussed the idea of the enervation of the muscles, the coordination of their activity, the fine articulation of every joint as having a powerful effect, though not immediately discernible, on the overall athletic performance of a horse. The unseen having a major effect on the endurance and ability of the individual. 

Many years ago, when I was still writing a column for the Alaskan Malamute Club of America's Newsletter, I discussed the inheritance of mitochondria. Mitochondria are the energy producing organelles in a cell. How many of them and how efficient they are at doing their job, whatever job that cell might do, all come from genetics. But not male and female genetics. Just female genetics. Why? Because the mitochondria are in the cytoplasm of the cell, not the nucleus, where the bulk of genetic material is contained. When a female mammal produces an egg, it has a nucleus with its genetic contribution to the future offspring ready to merge with the nuclear material of the male sperm. The egg is also surrounded by cytoplasm. The sperm has no cytoplasm. Therefore the offspring must rely solely on the quality and quantity of the mother's mitochondria, because the entire new organism comes from the division and embryological development of what started out as that fertilized egg cell. At the time I wrote the article, I urged breeders who valued working ability to look carefully at their bitches, even more so than which big, famous, beautiful stud dogs they chose. For work performance, the value of the bitch should not be underestimated. As an aside, I mentioned a line from the old movie Ben Hur. When he was admiring the four white horses owned by the Arab trader, the owner said "Ah, you should see their mother!" (Note: NOT their father!)

Now in these two recent articles, we have more reason to honor the female contribution to athleticism.  It seems that many top performing racehorses have or had heart size as a significant factor in their sport. When these horses turn out to be prolific sires of winning offspring or descendants, it is through their daughters, on the X chromosome that this superior sized and functioning organ is handed down. The pattern has been becoming more apparent since the eighteenth century. These larger hearts are, according to Bonner's article, "perfectly normal in every other respect… with no pathological changes that might have caused the enlargement". Of course the heart is only one of several factors - including conformation, respiratory capacity, biomechanics, nutrition and the "right" owner. Bonner also mentions that there are a number of published studies that "have correlated higher heart scores with higher performance levels in racing Standardbreds, event horses, and endurance horses, as well as racing greyhounds and even human Olympic athletes."

Could it be that in the fierce, brutal selection for performance efficiency which marked the process of selection in forming the Inuit Sled Dog, such a superior heart became, of necessity, more common in the breed? Well, as things look now, we will probably never know. As more critical numbers of true Inuit Dogs are lost to cross breeding, poor record keeping, and sold off to unsuspecting tourists as pets (soon after to be abandoned or put down); or disregarded as obsolete or "inconvenient" by modern peoples, the chance is slim to none. Will the world look back wistfully at what was lost?  Can anyone see past five minutes from now? Extinction is forever.