Further studies on horn aberrations in Dall's sheep (Ovis dalli dalli) from Yukon Territory, Canada.
J Wildl Dis
; 20(2): 125-33, 1984 Apr.
Article
em En
| MEDLINE
| ID: mdl-6737607
ABSTRACT
The prevalence of horn aberrations in Dall's sheep from the Kluane Lake area of Yukon Territory observed during July 1982 represented 1% of the total population and 7% of rams 6 yr or older. Ewes were not considered in these percentages because they were too difficult to inspect by aerial survey. When these data were combined with other data collected from 1977 through 1981, the prevalence equalled 2.4% of the total population and slightly exceeded 16% in mature rams (greater than or equal to 6 yr). The anomaly followed necrosis of the terminal region of the horn core and the sequestering of portions of the core within the sheath as the sheath continued to grow. Sheath that was produced after the core was anatomically altered resulted in abnormal growth patterns of the horn. Rams with aberrant horns could not maintain homeostatic temperatures within horn cores when horns were experimentally exposed to -80 C for 30 min. Histologic examination of superficial and cornual vascular systems did not reveal any structural alterations that would restrict blood flow within cores of affected horns. Examination of museum specimens consisting of 130 skulls from rams and 81 from ewes collected from Alaska, USA, Yukon Territory, Canada, and Northwest Territories, Canada, established only one ewe and no rams with the horn aberration. The skull was from a ewe and had both horns affected and was collected from the Joe River Drainage, Yukon Territory in 1912.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Doenças dos Ovinos
/
Cornos
Tipo de estudo:
Etiology_studies
/
Risk_factors_studies
Limite:
Animals
País/Região como assunto:
America do norte
Idioma:
En
Revista:
J Wildl Dis
Ano de publicação:
1984
Tipo de documento:
Article