White manes and tails Print E-mail
Written by Rachel   

What causes the mane and tail to become flaxen?

There are a couple genes that can cause the flaxen effect. The flaxen gene and the silver dapple gene are the most responsible for causing the flaxen look. However both act in different ways and combine with a variety of different genes to create the flaxen look. Someone with no knowledge of color genetics would not be able to tell the difference but once an understanding of the way these genes work is established then it is not all that complicated.

I will briefly touch on the silver dapple gene but my main focus will be the flaxen gene.

The silver dapple gene is a dilution gene and is inherited as a dominant trait. Since it is a dominant gene the horse only requires one dominant allele for the traits to be expressed.  The gene causes the entire body to lighten but the mane and tail will lighten the most taking on a flaxen or silver color.

This gene, however, only effects horses with a black base coat (black, bays, buckskins, blue roans, bay roans). Horses with a red base coat may carry the silver dapple gene but they do not show the traits. This makes it possible for the silver dapple gene to be past to the next generation without anyone knowing it exists.

Horses showing the silver dapple gene are often mistaken for horses carrying the flaxen gene as the traits shown are very similar. One would need to understand the difference between the two genes to tell them apart. As I said before the silver dapple gene is a dominant gene however its effects can be masked by the grey gene. The grey gene causes the horse to lighten with age where as silver dapples often darken with age.

The flaxen gene causes many of the same traits as the silver dapple gene. Ironically the way these two genes works is almost completely opposite. The flaxen gene is a modifier gene that causes the mane and tail to become white or cream color.

Many think that the flaxen gene is recessive while others believe that it cannot be a recessive claiming that two flaxen horses do not always produce a flaxen foal. This may be true but it is possible that there are other genes that may mask the expression of the gene . Until science determines the actual mode of action, the theory that the gene is recessive provides the best explanation as to the workings of this gene.

The genetic symbol for the flaxen gene is F. If the horse carries to dominant FF genes, then there is no expression of a flaxen trait. If the horse carries one recessive "f" and one dominant "F", there is still no expression of the flaxen gene. Only when the horse has two recessive "ff" canl the horse exhibit a flaxen mane and/or tail as long as the gene is not supressed.

What is also known about the flaxen gene is that it only affects horses with the base color of red. Horses with the base color of black like blacks, bays, buckskins etc. do not show flaxen gene traits. They may have two recessive copies of the flaxen gene but it is somehow surpressed. They can, however, carry the gene and pass it on to future generations.

It is also known that the flaxen gene does not always work equally on both the tail and mane. One may be flaxen while the other is not. The reasons for this are still unknown.

I found this gene especially interesting so I decided to do a little case study of my own to see if the theory of the flaxen recessive gene could be correct. I looked at four mares and one stud. All four of the mares are out of a chestnut stud called “That’s Terrific”. The mares Dams are all related in that they have the same Dam and three have the same sire. The first mare, Bell, is a sorrel. The second mare Foxy is a sorrel with a flaxen mane and tail. The third mare Morra is a chestnut and the forth mare Lady is a sorrel. Based on the fact that the Foxy exhibits the flaxen trait both the sire (That’s terrific) and dam would have to be carriers. The four mares were bred to a brown stud called “Scotto Spider” aka Spider. Bell, Foxy and Morra all produced foals with a flaxen mane and tail when bred to Spider but when bred to other studs no flaxen traits were exhibited. From this I can determine that Bell, Morra and Spider are all carriers. The mare called Lady produced no flaxen foals when bred to any stud therefore she cannot be a carrier of the flaxen recessive allele.

Based on the information I was able to find and the study of these horses I have come to the conclusion that the theory that the flaxen gene is recessive is the closest. The gene cannot be dominant or else mares like Bell and Morra would not be able to produce flaxen foals when bred to Spider because none of them are flaxen. However, I feel that it is not simply enough to say that the gene is recessive. I think that there is a good possibility that there are other factors that contribute to the flaxen gene. It is a study that is just beginning and I look forward to learning more as the knowledge about it is expanded.

Works Cited

"Dilutions." The Horse Colors Site. 2007. 7 Mar. 2008 .

"Horse Coat Color Tests." Veterinary Genetics Laboratory. 2008. University of California. 7 Mar. 2008 .

"Modifiers." Equine Color Genetics Information. Nov. 2003. 7 Mar. 2008 .

"Silver Dapple Gene." Wikipedia. 17 Mar. 2008. Wikimedia Foundation, Inc. 7 Mar. 2008 .

This article was submitted by Rachel - a student in our On-line Coat Color Genetics Class. If you would like to submit information on this topic, please email it to us as This e-mail address is being protected from spam bots, you need JavaScript enabled to view it

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