Stirling Collies

The ABC’s Of Collie Coat Color Inheritance

The four basic coat colors in collies are sable, tricolor, blue merle and white. With certain crossings of the merle factor, four other colors can be produced...sable merle, dilute merle (also called normal grey, maltese, maltese blue, or maltese grey), cryptic merle, harlequin merle, and the double dilute or also called a defective white merle. Deviations from the normal due to mutations, or linked recessive genes in certain individuals, can also result in the lethal grays, the sable faced tricolor, the chinchillas, etc. These Merle Variations are AKC Registered as Blue Merle, according to a recent vote by the Collie Club Of America in August 2018.  However, it is the purpose of this article to provide the reader with a simple reference chart concerning the more common color crosses as well as some of the less common crosses involving the merle factor. Thus, we shall eliminate the rarer combinations as well as genetic technicalities.

The percentage ratios (1:1, 1:2:1, etc.) of the resulting POSSIBLE progeny are factual, but not necessarily a POSITIVE end result of each breeding as Nature’s whimsies cannot be computer programmed due to the Laws of Chance.

For simplification, the following letters represent colors.

S.....SABLE, dominant over tricolor. Shadings may run from straw thru red to dark mahogany.

a. PS.....PURE SABLE. Usually a clear shade of straw, or orange red without dark masking or fringes.

b. tS.....TRIFACTORED SABLE. Sable collies carrying the tricolor gene in conjunction with the dominant sable gene. Usually, (but not always), a dark orange to a very dark mahogany in color with dark masking and fringes.

tri.....TRICOLOR, recessive to sable. Black collies with white and tan markings on sides of muzzle, above eyes, sides of checks, chest and inner margins of legs.

M.....MERLE. A dominant dilution gene, which in combination with sable, or tri genes, produces merled collies.

a. BM.....BLUE MERLE. Bluish gray, with black splotching, carrying sable markings in the same pattern as the tricolor. Color results from the interaction of the dominant dilution gene (M) with the tricolor gene (t).

b. SM.....SABLE MERLE. “Sable spotted collies”. Color results from the interaction of the dominant dilution gene (M) on the sable color. At birth, all sable merles exhibit a bluish tinge on tail and muzzle, which disappears in a few weeks. Brownish merling on body, or head may, or may not remain at maturity, and thus these individuals, if they have dark eyes can be mistaken for a “normal” sable. However, many sable merles inherit blue, or blue flecked eyes...a sure sign of a merle.

1. PSM.....PURE SABLE MERLE. Usually, a light or even “washed out” sable at birth with brown merling. At maturity, quite often these collies lose their merling and coat color becomes a clearer red. No tricolor gene is present in their makeup.

2. tSM.....TRIFACTORED SABLE MERLE. Usually, a darker sable color than the PSM with dark brown merling, which quite frequently is still visible at maturity. The tricolor gene is present in conjunction with the sable and merle gene.

w.....WHITE. These collies are the result of a cross between either two white parents or white factored parents. Color is carried on a recessive gene (w) and is inherited INDEPENDENTLY of sable, tri, or blue merle, and may occur in combination with ANY of them. A blue headed white is just as sound and normal a collie as the tri, or sable headed white. These are not to be confused with the white merle whose “white” color results from the double dominant dilution merle gene, whereas the white color of a blue headed white results from the recessive gene (ww) and its blue color from the normal interaction of the merle gene with tricolor.

a. wf.....WHITE FACTORED. Colored dogs usually with large white frill, heavy white tail tip, possibly a body splash of white hairs and white extending upward from hind feet over stifle to meet the white under body.

b. non wf.....NON WHITE FACTORED. Regular colored collies NOT carrying the recessive white factor.c.

WM.....WHITE MERLE. DEFECTIVE WHITES, resulting from the combination of two merled parents. These collies inherit the dominant dilution gene (M) from both parents. Thus, color is diminished almost to the vanishing point by the gene in duplex. They are almost white in appearance and may or may not have a few merling spots. Eyes, IF present, are pale blue; skin, including the eyelids, lips, nose and pads are pigment less except within an area of merling; hearing and sight severely impaired. These are commonly destroyed at birth. If a white merle is raised to maturity and is from a BM to BM cross, it can be bred to a tricolor and will produce 100% blue merles. This is not true of white merles carrying the PS genes, or the tS genes when bred to a tri.

Parents.......Progeny

PS + PS =     PS

PS + tri = tS

PS + tS =     (1) PS / (1) tStS + tri = (1) tS / (1) tri

tS + tS =     (1) PS / (2) tS / (1) tri

tri + tri =     tri

BM + tri = (1) BM / tri

BM + BM =     (2) BM / (1) tri / WM

BM + tS = (1) tS / (1) BM / (1) tSM / (1) tri

BM + PS =     (1) tS / (1) tSM

WM + tri = BM

tSM + tri = (1) tSM / (1) BM / (1) tS / (1) tri    

tSM + tS = (2) tS / (2) tSM / (1) BM / (1) tri / (1) PSM / (1) PS

tSM + PS = (1) PS / (1) PSM / (1) tS / (1) tSM    

PSM + tri = (1) tSM / (1) tS

white + white = white

Wf + Wf = (1) white / (2) Wf / (1) non Wf    

WfBM + white,tri head = (1) white, BM head / (1) white, tri head / (1) Wf BM / (1) Wf tri

white + non Wf = Wf

Original Article Was By Dot Gerth - I modified with it with new info by Dr. Leigh Anne Clark and Susan Murphy (2018)