Unser Haushund: Eine Spitzmaus im Wolfspelz? - Wolf-Ekkehard ...

377There is a certain amount of pain accompanying any movement or manipulation of the affected limb during the firstday or so of the condition. Later, however, there seems to be no pain associated with the lameness. After the animalreadjusts, and again learns to walk in a limping fashion, the involved muscle groups never recover their function;and wilted, atrophied regions in the thigh may be strongly marked in many of the animals. The attack of paralysis mayinvolve only one leg at a time, although usually both hind legs are simultaneously affected.There have been produced in all seventy-eight of these F 1 hybrid St. Bernard-Danes, and more than fifty of themhave lived to reach the stage of life when the above-described symptoms appear. Practically every one of the fiftyhas been paralyzed in an almost identical fashion. We have attempted the use of every reasonable precaution inorder to make certain that no infectious disease and no food deficiency could be involved. These animals have been bornduring all seasons of the year, and puppies of a number of other breeds have in all cases been kenneled on both sides ofthem, and all were similarly fed. In spite of this, no puppy of another breed — out of more than five hundred bred inthe kennel — has shown this definite type of paralytic condition. The first several litters of the St. Bernard-Dane hybridswere somewhat neglected; their food was probably not properly balanced and they were poorly looked after. On thisaccount it was decided to breed and rear further litters, with carefully balanced food conditions, while the kennel was inpractically perfect health. Under this present careful and efficient management, the paralysis occurs in one after anotherof these pups as previously, with almost scheduled regularity.The nature of this crippled condition has not yet been fully analyzed; and it is quite uncertain whether the conditionarises in the nerve trunks or in the spinal cord. The muscles once lost or paralyzed are never regenerated or restored. Itseems clear from the sudden onset of the paralysis, however, that the condition is not a type of hereditary primarymuscular atrophy, but is probably of nervous origin. In any case it is perfectly clear that these St. Bernard-Danehybrids inherit a constitution which exhibits this condition in practically 100 per cent of the individuals.A very similar paralysis of the hind extremities is occasionally met with in certain stocks of the St. Bernardbreed, and it occurs, though very rarely, in the great Dane. The combination of the two breeds seems to bringabout an accentuation of this defective condition in the bind legs. The lower illustrations in Fig. 69 show the adulthybrids with badly wilted thighs, though these dogs are otherwise large and often handsome specimens. The fore quarters,neck and head are particularly strong and heavily developed.Further Generations from Giant Dog CrossesThere appears to be a certain amount of sterility among the St. Bernard-Dane hybrids, as there occasionally isamong the St. Bernards. Yet we have now succeeded in obtaining back-crosses with the hybrids on both parent stocks, aswell as a second, F 2 , generation from inter se matings among the hybrids themselves; see Fig. 70. The numbers ofanimals at present available from these back-crosses and the second generations are not yet altogether satisfactory for adefinite analysis of the characters involved in the crosses, yet they are instructive for brief consideration.When a male hybrid St. Bernard-Dane was bred back to a pure St. Bernard female a large litter of thirteen pupswas produced by this excellent dam. Four of the puppies died very soon after birth, as frequently happens in litters ofthis size.A few of the pups in large litters are smaller than their mates; they have probably not been so favorably locatedduring development in the overcrowded uterus. These less vigorous specimens usually succumb during the first few dayssince they are not successful in the struggle for food from the mother and hence remain weak and hungry. All of themembers of small litters, up to as many as eight, may frequently survive as uniformly vigorous animals.Nine out of the thirteen puppies from the back-cross on the St. Bernard female lived to be more than three monthsold. Up to this age they were all strong, attractive-looking, lion-like young animals, vigorous feeders and most rapidlygrowing. After three months of age, here again, one after another of these young dogs became paralyzed in theirhind extremities to different extents. The mildest expression was a dragging or limping of the hind legs, while others