9. X-Pigeons |
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at - Ataxic
The word ataxia comes from Greek which means “lack of order”. Ataxia is a neurological sign consisting of lack of voluntary coordination of muscle movements. In other words, it is a non-specific clinical manifestation implying dysfunction of the parts of the nervous system that coordinate movement. In pigeons we have very limited data for ataxia. Riddle and Hollander (1943) and Riddle (1947) reported this mutant; expression varied considerably, even in individual specimens. Inheritance typically recessive, gene symbol at.
According to Oscar Riddle, in 1914 a female pigeon produced from “reproductive overwork”, which showed a marked lack of power over the voluntary movements of the head and body. This lack of coordination was practically completely lost in the adult bird. This female was bred to two different males and derangement has been inherited through four generations descended from either male. The affected offspring have shown many degrees of the lack of muscular control where some at first been classed as normal and have later developed marked irregularity of movement, and some marked disturbances when young and have later recovered. The more usual manifestations of the disorder are: Nodding of the head, or nodding and swaying of the head and neck; unsteady gait; tipping (somersaulting) backwards or forwards; falling on the side; very irregular flight, the bird even flying backwards. The same bird often exhibits two, three or perhaps all of these irregularities. Although in a few cases the movements have seemed fairly normal when the bird was at perfect rest, all affected birds were unable and uninclined to sit on a perch, remaining constantly on the ground, or on a flat ledge. In the most affected individuals, there seem to be no movements whatever of wholly normal coordination; in average cases, however, the disturbances are much increased under excitement, fear, or any attempt at increased or more vigorous movement.
In this study, 175 young have been raised by Riddle to the age at which the disorder might be exhibited, and 119 were classed as normal, 46 as affected. The first mating of the original female gave 33 normal and 3 affected. The affected offspring when mated to their unaffected relatives gave 11 normals to 14 affected. Similar affected individuals outcrossed have yielded 4 normals to 0 affected. There is some evidence that more of the affected individuals than normals die before attaining the age required for classification. The details bearing on the method of inheritance (chart demonstrated) make it appear that the new character is, with some irregularities, a Mendelian recessive.
“Ataxia, a staggering behavior somewhat like drunkenness, was a mutant discovered by Riddle. It proved to be highly variable but fairly reliable Mendelian recessive and was given the symbol at. I maintained this mutant for many years, but eventually failed to get it propagated. Needless to say, it was difficult to manage, especially in a flock pen, and even a fairly well-coordinated bird would occasionally go into convulsion for no obvious reason. The cerebellum of the brain is small in ataxic birds" Willard F. Hollander, Origins and Excursions in Pigeon Genetics P.125.
According to Hollander tumbling and rolling seem not to have any relation to ataxia, although “loss of control” in extreme examples does resemble a convulsion. “Entrikin’s study (Journal of Heredity 63 pages 351-354, 1972; PGNL #59, 1971) is the most extensive to date. The data indicated multiple-factor inheritance, but a main factor ro was hypothesized; environmental effects were also shown to be important. A report not noted by Entrikin was printed in APJ 56 page 293, 1967, by A. H. Kopp, who crossed a “mad” Roller cock with a Fantail hen. He got 3 F1 which were “excellent high-fliers, and flew for several hours each time liberated. One hen was lost, and the other two rolled down when they were about a year old, the cock killing himself.” Kopp also noted that F1 from crosses of Parlors with Tipplers and with Birminghams were variably intermediate. No doubt much more such information could be dug out of fanciers’ publications” Willard F. Hollander, Origins and Excursions in Pigeon Genetics P.125.
The brain of the pigeons with ataxia, particularly the cerebellum are smaller than normal. Ataxia can show in pigeons as a symptom of many diseases. For instance, during the first quarter of 1992, fancy pigeons in the Dirab area in Central Saudi Arabia experienced a severe disease which was very similar to the neurotropic Newcastle disease of chickens. Affected pigeons were listless, anorexic, showed ataxia and produced watery droppings. Torticollis and other nervous signs, including hiding the neck between the shanks, were also seen. In addition, Salmonellosis (Paratyphoid) can cause neurological signs if the infection localises in the meninges. In these cases affected birds may be ataxic, unable to hold their head in a normal position, lie on their side, and difficulty eating.
References:
1. Hollander, W. F. The
inheritance of "scraggly" plumage and of ataxia in the
pigeon. Journal of Heredity, 34:167-72
2. Hollander, W. F. (1983).
Origins And Excursions In Pigeon Genetics: A Compilation. Burrton,
Kan.: The Ink Spot.
3. Riddle,
O. (Jan 1918). A case of hereditary ataxia (?) in pigeons.
Proc Soc Exp Biol Med 15:56—58
Copyright May, 2011 by Arif Mümtaz