By Carol Beuchat PhD
While digging around for information about the history of sled dogs for my course Biology of Dogs, I ran into a fascinating paper about osteoarthritis in the working dogs that were kept at the scientific field stations on Antarctica for several decades. The thing that was so remarkable is that these dogs developed osteoarthritis by the time they were about 8 years old, but they had no evidence of hip dysplasia. None.
Read on...
Read on...
In the 1940s, the British established scientific stations on Antarctica. Early on, the program was known as the Falkland Islands Dependencies Survey (FIDS), and it was renamed in 1962 as the British Antarctic Survey.
For transportation and hauling materials, residents relied on dogs that were bred at the stations from the descendants of the early dogs brought to the continent.
"The canine population of the Falkland Islands Dependencies is divided between the stations and has fluctuated in number between forty and 200. Dogs are frequently moved from station to station and must be considered as one and not separate breeding units.
There have been three introductions of Huskies into the Falkland Islands Dependencies. Two shipments from Labrador arrived at the beginning of I945 and 1946. In 1945 about forty dogs came from the coast south of Hopedale and in 1946 another forty from north of this settlement. These animals were not the best in the area, but rather the small and unwanted beasts.
In 1954, twenty-one dogs were shipped south; eleven of these had been selected as the best of the British North Greenland Expedition, 1952-54, pack; four more were their progeny; three dogs came from the Northwest Territories of Canada and three from Britain. The last trio were out of a Husky of Labrador parentage and the sire of one pup, although born in Labrador, had won fame in Graham Land as leader to V. E. Fuchs." (Taylor: The breeding and maintenance of sledge dogs)
There have been three introductions of Huskies into the Falkland Islands Dependencies. Two shipments from Labrador arrived at the beginning of I945 and 1946. In 1945 about forty dogs came from the coast south of Hopedale and in 1946 another forty from north of this settlement. These animals were not the best in the area, but rather the small and unwanted beasts.
In 1954, twenty-one dogs were shipped south; eleven of these had been selected as the best of the British North Greenland Expedition, 1952-54, pack; four more were their progeny; three dogs came from the Northwest Territories of Canada and three from Britain. The last trio were out of a Husky of Labrador parentage and the sire of one pup, although born in Labrador, had won fame in Graham Land as leader to V. E. Fuchs." (Taylor: The breeding and maintenance of sledge dogs)
Because these dogs were essential for both work and survival, the scientists had an interest in learning about their physiology and performance in the harsh conditions. They kept records of both general husbandry and a variety of experiments.
One thing of great interest to them was the working life of the dogs. Most of the dogs were able to pull sleds until about 8 years old, after which arthritis usually reduced performance and the dog was removed.
One thing of great interest to them was the working life of the dogs. Most of the dogs were able to pull sleds until about 8 years old, after which arthritis usually reduced performance and the dog was removed.
"Dog team drivers of the British Antarctic Survey have come to accept the fact that otherwise healthy Antarctic sledge dogs are usually incapable of further work by the time that they are 8 years old. Since this is less than might be expected of a dog of the husky's size and weight under normal conditions, an investigation into the possible causes of the decline of the ageing husky was started in 1963- 64." (Bellars & Godsal 1969)
They evaluated the hips and elbows of 34 dogs that ranged in age from 1.5 to 10 years old. They found no evidence of hip dysplasia in any of them. What they did observe instead were signs of wear and tear associated with hauling loads.
The erosions of the articular canilage were found to be in a uniform position on the articular surfaces of the humerus and femur. They varied in size and depth, but were invariably bilaterally similar. On the surface of an affected humerus the erosion was on the caudal curvature of the articular cartilage; on the femur it was found on the dorsal aspect, extending cranially and caudally in the more advanced cases. Severe cases also showed smaller erosions on the opposite surfaces of the glenoid cavity of the scapula and the acetabulum. These erosions are found, therefore, in the areas of greatest pressure when a dog is pulling, i.e. on the areas in direct opposition when a dog is leaning against the weight of the loaded sledge, with its limbs in extension retraction and, in the case of the hindlimb, slightly abducted.
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Study at post-mortem examination and later showed that there was no evidence of shallowness of the acetabulum in any of the dogs examined. Likewise, the heads of femora and humeri showed normal conformation. There was some re-shaping in the most severely affected cases...The hip joints showed no evidence of sufficient abnormality to be called hip dysplasia. (Bellars & Godsal 1969)
Read that again:
"The hip joints showed no evidence of sufficient abnormality to be called hip dysplasia."
"The hip joints showed no evidence of sufficient abnormality to be called hip dysplasia."
In the x-rays below, they noted that the hips of the the 1.5 year old dog on the left were completely normal, and the 5 year old dog on the right had evidence of erosion on the head of the femur (at the arrows). The shape and depth of the acetabulum (the socket) in both dogs was normal, as it was in all of the dogs they examined.
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They concluded that the decline in working ability of the dogs with age was the result of osteoarthritis of the hip and shoulder joints, and that "hip dysplasia does not occur in a representative selection of these dogs". They further remarked that in the 700 dogs which had been reared at the station, none showed the signs of early hip dysplasia (pain, femoral head subluxation, or gait abnormalities) that are often seen in Labrador Retrievers or German Shepherd Dogs.
"By virtue of these findings, and the conformation shown in the radiographs, we feel justified in believing that hip dysplasia, as seen in dogs in the United Kingdom, is not present in the Survey's sledge dogs. Such degenerative changes as are apparent are considered to be secondary changes due to aging, exacerbated by "special occupational activities" and "abnormalities of gait"."
Remember, there was nothing special about the original breeding stock of these dogs. They came from various places, and it was even noted that "These animals were not the best in the area, but rather the small and unwanted beasts.' There were no fancy living accommodations, and dogs had to earn their keep as working sled dogs or they were eliminated from the colony. A portable x-ray machine was brought in to make the films used in the study, but otherwise the dogs were not evaluated for hip structure. Because none of the dogs had hip dysplasia, there was no control program like the ones run today. And remember, these were not small dogs, and they were expected to pull at least their own body weight for dozens or even hundreds of miles, day after day after day. For them, the osteoarthritis that eventually developed was a consequence of aging and biomechanical wear and tear on the articulating surfaces of the femur and humerus.
Many studies of hip dysplasia show it to be a consequence of both genetic and environmental factors, some of which have been studied. But we still don't really know what causes it or how to prevent it. The Antarctic researchers were aware of the high incidence of hip dysplasia among pet dogs in the UK, but they offered no explanation for why their working dogs should be completely free of any evidence of dysplasia.
Still, we have more questions than answers.
You can download a copy of the publication HERE.
Still, we have more questions than answers.
You can download a copy of the publication HERE.
In 1993, the last descendants of the Antarctic sled dogs were ordered to be removed from Antarctica by the Madrid Protocol. This video is about the last trip taken by these iconic dogs and their removal from Antarctica, and it includes some interesting historic footage and information about the history of the Inuit dogs of the Arctic.
REFERENCES
Bellars ARM & MF Godsal. 1969. Veterinary studies on the British Antarctic Survey's sledge dogs: II. occupational osteoarthritis. British Antarctic Survey Bulletin 22: 15-38.
Bellars ARM & MF Godsal. 1969. Veterinary studies on the British Antarctic Survey's sledge dogs: II. occupational osteoarthritis. British Antarctic Survey Bulletin 22: 15-38.
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