Conditions Associated with Coat Color
This webpage was last updated on Feb. 13, 2004 by Sheila Schmutz, Ph.D. firstname.lastname@example.org
Oculocutaneous Albinism (OCA) is a condition seen in Angus cattle. It affects the black coat color to change it to a coppery red tinged black, but the main effect of this recessive condition is an eye abnormality. The eye looks abnormally white. The animal avoids sun and it is assumed this condition makes it quite uncomfortable to be in the sun. Shade must be available in the form of trees or a shed for such animals.
Preliminary data suggests that this is not a tyrosinase mutant nor a tyrosinase related protein 1 mutant based on examination of genomic coding sequence. OCA exists in at least 3 forms in humans and these two genes are implicated in OCA-1 and OCA-3 or ROCA.
Albinism is occasionally seen in cattle. It eliminates pigmentation from the hair, skin, hooves, nose leather. It causes the eye to look pink but such animals often try to keep their eyes closed. This animal was found and photographed by Dr. Merete Fredholm in a Holstein dairy herd.
The tyrosinase sequence of it was normal. Both tyrosinase positive and tyrosinase negative forms of albinism have been described in many species of animals. The gene causing the tyrosinase-positive form of albinsim affecting this Holstein calf is not known. The paper by Foreman et al. (1994) mapped tyrosinase using somatic cell hybrid data and so the type of albinism they mapped would be the tyrosinase-negative form of albinism.
On the other hand, this Braunvieh calf, Snowdrop, has a mutation in her tyrosinase gene. Her mutation causes the tyrosinase she makes to be incomplete. Both of her parents were found to be carriers of this mutation also. Albinism was already reported in Braunvieh cattle in 1933.
White Heifer Disease
White Heifer Disease is a reproductive problem in a proportion of white females in breeds such as Belgian Blue and Shorthorn where the white coat color is inherited as a recessive condition with the alternative coat colors being roan for the heterozygote and another solid color for the opposite homozygote. The problem is a result of incomplete development of the female reproductive tract.
Black Hair Follicular Dysplasia
Black Hair Follicular Dysplasia has been described in cattle and dogs. This disorder causes a defect in the quality of the hair and follicles in only the black haired portions. Patchy hair loss occurs only in the black areas. The white spots have normal hair and skin histologically.
Rat-tail Syndrome is mentioned by ranchers more often than in the scientific literature. It is described in O'Brien et al. (1996) as a "short, charcoal-coloured hair coat and an abnormal, crooked, shortened tail switch". They further say it usually occurs in crossbreds of Angus and Simmental or Hereford. The jury is still out on whether this condition causes other than cosmetic problems.
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