COLOR INHERITANCE IN MAMMALS 



IX, The Dog —Many Kinds of White Patterns Found — Albinism Resembles That 

 of Other Mammals in Reducing Red More Than B'ack— Inherit- 

 ance of Black-and-Tan Requires Further Data — Red 

 and Liver Simple Recessives 



Si'WALL Wright 

 Bureau of Animal Industry, WasJiington, D. C. 



SOLID BLACK DOG TvCEB 



lao 



las 

 lb 



R,r 



C,c 



R — roan ^ 



\' — piebald (unn 

 uncertain)- 



factor 



c — imperfect alljino (slate- 

 Ijrown coat, l)lue iris, 

 red pupil) 



2a, 

 2a 3 



2b 



E,e e — red (eyes unaffected) 



B,b b — liver (brown coat, skin 



and eyes) 

 Classification explained in paper on the 

 mouse, JouRXAL of Heredity, 8:,i73, 

 August, 1917. 



THERE are many kinds of white 

 patterns in dogs. There are the 

 common, irregular, piebalds of 

 many breeds; the black eyed 

 whites, such as in Bulldogs; the roans 

 occasionally found among Cocker Span- 

 iels; the spotted Dalmation Coach Dogs; 

 the albinotic Pekinese vSpaniels, etc. 

 Barrow^s and Phillips^ find that the 

 blue roans and red roans, in Cocker 

 vSpaniels, differ from blacks and reds 

 respectively, by a single dominant fac- 

 tor. The}^ also find the piebald pattern 

 to be dominant. Much more work is 

 necessary, however, before the great 

 variations in extent and pattern in pie- 

 bald dogs may be considered to be under- 

 stood. Most black e3^ed whites, as 

 Castle- has suggested, are probably 

 comparable to the black ' eyed white 

 guinea-pigs and mice in ]Dossessing an 

 f>vi-ff.rpp form of the piebald pattern. 



Dogs, with a very irregular, a s\'m- 

 metrical t\-p3 of ]jiebald pattern, are 

 often wall-eyed according to Pearson, 

 Nettleship and Usher. ^ Among other 

 breeds they mention in this connection, 

 the Old English Sheep Dog, the Dappled 

 Dachs and the Harlequin Great Dane. 

 The Merled Collies, which they also 

 mention, probably belong in a different 

 category. In them, it does not appear 

 to be an irregular piebald pattern, which 

 has invaded the eye; but a general 

 dilution factor, which reduces red to 

 white, and black to slate blue, affecting 

 the eyes as well as the coat. The pie- 

 l^ald pattern may also invade the inner 

 ear, and in some way bring about deaf- 

 ness. Thus Pearson, Nettleship and 

 Usher mention deafness as common 

 among white Bull and Fox Terriers, 

 which are extreme piebalds, but note 

 its absence in whites of several other 

 breeds including Collies and Pekinese 

 Spaniels, where a dilution factor is re- 

 sponsible for the whiteness. This deaf- 

 ness in white dogs, calls to mind the 

 deafness of blue-eyed white cats which 

 w^as noted by Darwin. 



A white, w4th dark points, is oc- 

 casionally found among Cocker Spaniels. 

 Barrows and Phillips'* find that this is 

 due to a recessive factor, which reduces 

 red to white, but black merely to a slate 

 blue. Whether it also affects the eye, 

 they do not mention. These authors 

 speak of another kind of dilution in 

 Cockers, which they have not tried to 

 analyze. Thus, livers var}^ from dark 



'Barrows, W. M. and J. N. Phillips, 1915. Journal Heredity, 6:387-397. 



2 Castle, W. E., Genetics and Eugenics, pp. 138-140. 



3 Pearson, K., E. Nettleship and C. H. Usher, 1913. A monograph on albinism in man. 

 Part II, pp. 460-512. 



^Barrows, W. M. and J. N. Phillips. Loc. cit. 



87 



