Tiger piebald complex

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Appaloosa with full tiger drawing. The dark skin shimmers through the white fur, giving the spots a gray halo.

The tiger piebald complex , known as the leopard complex in English , comprises several piebald patterns in horses caused by the same gene . This also includes completely white horses and those with Varnish Roan markings. Small, round, dark spots on a white background often appear in the spotted patterns.

features

In horses with tiger spotting, the white dermis can be seen even with the eyes normally open.

There are horses without a visible spotted pattern, which only show the darker basic color. Others have an oval white spot (saddle pad) of different sizes starting from the croup, which in the lightest horses has spread over the entire horse. Usually the skin is pink under white fur and dark under dark fur, but the dark skin often extends a little way from the dark fur into areas where the fur is already white. Often small, penny to apple-sized, round, dark spots appear on a light background in the white saddlecloth. Conversely, there are also small light spots on the dark areas of the fur. The hooves are often streaked because of white and black spots on the edge of the hoof. Dark areas of fur usually become lighter in the course of life, as more and more white burin hairs sprout in them.

If the tiger piebald gene is homozygous, it leads to congenital night blindness . Heterozygous animals that have the gene only once are not affected.

Variations

  • Black-backed tiger

  • Snowflake tiger, almost monochrome

  • Older Varnish Roan

White born

The horse is born white and does not go through a color change. White borns are always homozygous for the gene.

Volltiger

A full tiger (English leopard ) is a horse that has many small, mostly round, dark spots on a white background.

Black-backed tiger

Black-backed tigers (English: Blanket , from Turkish: çaprak , 'saddle blanket') are tiger pucks in which a significant part of the horse shows the normal basic color, while a rounded area is white starting from the croup . The size of the saddle pad is very variable, occasionally stains appear within it.

Snowflake tiger

The snowflake tiger has small white spots spread over its body.

Varnish Roan

Similar to the mold, white hairs appear in the fur of the Varnish Roan over the years. Only the skin areas where bones lie close under the skin remain dark. These are, for example, the front legs up to the carpal joint. The dark color runs out in a point at the front. On the hind legs it extends to the hocks. There are also dark spots at the front and rear of the leg (elbow joint and knee joint). A dark V remains in the front of the face, while the forehead and sides of the head become largely white. The mane and tail also stay a little darker. → For the names of the body parts see: Exterior (horse)

Possible confusion
  • Mold in the mold phase: The face becomes light first, especially in the area where the dark V persists in the Varnish Roan.
  • Graver-haired horse : The face remains completely dark, the dark color extends from the legs to the elbow or hip joint. They remain roughly the same color throughout their life, if you disregard the fact that the amount of burin hair changes with the seasons.
  • Rabicano : The prickly haired areas are less extensive than in the prickly haired horse and are predominantly in the area of ​​the chest. The horses do not get lighter in the course of their life.

Monochrome animals

The gene does not affect the appearance of every horse.

Transitional forms

Since all of these colors are produced by a single gene, there are smooth transitions between them. Tiger piebalds with dark areas of fur, like the Varnish Roan, can always get lighter in the course of their lives.

Pintaloosas

Horses that have a tiger piebald gene in addition to the Tobiano gene are known as pintaloosas , a combination of the words pinto (American for "piebald") and appaloosa .

Spread among the races

The European tiger piebald, European Appaloosa pony , Appaloosas , Knabstrupper , Colorado Ranger and Nederlands Appaloosa ponies always have the typical tiger piebald pattern, but the gene also occurs in the Welsh pony , Noriker and the Pony of the Americas .

history

Replica of a representation of tiger piebalds in Pech Merle

In a cave painting dating from around 18,000 BC. BC, a horse is shown that looks like a typical tiger piebald. It was assumed that the points of the horse could only be meant symbolically. In the meantime, however, it has been proven that tiger piebalds actually existed back then.

In China, Ferghana tiger piebalds were referred to as the Heavenly Horses and play a major role in Chinese art. A picture of the Lipizzaner broodmares from 1727 does not mainly show gray, as we are used to today, but horses of various colors, including a tiger piebald. In France nobles, kings and saints were often depicted on tiger pucks. It was similar in England since the 12th century. In Denmark, Norway and Sweden, there are many works of art that depict tiger piebalds. Denmark received tiger piebalds from Austria in the 17th century, but had problems breeding the color pure, which is logical due to the genetic variance of the gene. Therefore the breeding was given up. Today's Knabstrupers descend from them. The Spaniards exported horses to North America, from which the horses that the Nez Percé bred are believed to have descended . The Appaloosas descend from them.

genetics

The gene for the tiger piebald complex is located on chromosome 1 of the horse and is abbreviated to LP (for English leopard spotting ). The well-known origins of leucism MITF , Steel and Kit as well as the oculocutaneous albinism type 2 were initially excluded as the cause. It was then found that it was a mutation of the TRPM1 gene which resulted in the expression of the gene in homozygous animals being reduced to 0.05% of the level in normal colored horses. The expression rate of heterozygous animals lies in between.

It is assumed that the reduced expression of the gene disrupts both the function of the bipolar cells of the retina and that of the melanocytes , so that both the night blindness of homozygous Appaloosas and the typical Appaloosa color can be caused by it.

Horses that have only one allele of the gene usually have less white fur than purebred animals. Nevertheless, it is not possible to tell with certainty from its appearance whether an animal has one or two alleles of the gene, since the color expression is very variable.

See also

Web links

Commons : Tigerschecken Complex  - Collection of images, videos and audio files

Individual evidence

  1. ^ Anna Stachurska, Anne P. Ussing, Ryszard Kolstrung: Tobiano and leopard alleles in felin pony population . In: Electronic Journal of Polish Agricultural Universities, Animal Husbandry . tape 5 , no. 1 , 2002.
  2. ↑ LS Sandmeyer, CB Breaux, S. Archer, BH Grahn: Clinical and electroretinographic characteristics of congenital stationary night blindness in the Appaloosa and the association with the leopard complex . In: Veterinary Ophthalmology . tape 10 , no. 6 , 2007, p. 368-375 , PMID 17970998 .
  3. ^ Gene Carr, Robert A. Lapp: Homozygous Appaloosa Coat Patterns. Retrieved December 31, 2012 .
  4. ^ A b c D. P. Sponenberg, G. Carr, E. Simak, KDP Schwink: The inheritance of the leopard complex of spotting patterns in horses . In: Journal of Heredity . tape 81 , no. 4 , 1990, pp. 323-331 , PMID 2177073 .
  5. ↑ M. Pruvost, R. Bellone, N. Benecke, E. Sandoval-Castellanos, M. Cieslak, T. Kuznetsova, A. Morales-Muñiz, T. O'Connor, M. Reissmann, M. Hofreiter, A. Ludwig : Genotypes of predomestic horses match phenotypes painted in Paleolithic works of cave art. In: Proc Natl Acad Sci US A. 108 (46), Nov 15, 2011, pp. 18626-18630. Epub 2011 Nov 7. PMID 22065780
  6. ^ History of the Appaloosa. In: Appaloosa Museum. Archived from the original on January 18, 2008 ; Retrieved June 1, 2011 .
  7. ↑ RB Terry, E. Bailey, T. Lear, EG Cothran: Rejection of MITF and MGF as the genes responsible for appaloosa coat color patterns in horses . In: Animal Genetics . tape 33 , no. 1 , 2002, p. 82-84 , doi : 10.1046 / j.1365-2052.2002.0742h.x .
  8. ^ RR Terry, E. Bailey, D. Bernoco, EG Cothran: Linked markers exclude KIT as the gene responsible for appaloosa coat color spotting patterns in horses . In: Animal Genetics . tape 32 , no. 2 , 2001, p. 98-101 , PMID 11421946 .
  9. ↑ RB Terry, S. Archer, S. Brooks, D. Bernoco, E. Bailey: Assignment of the appaloosa coat color gene (LP) to equine chromosome 1 . In: Animal Genetics . tape 35 , no. 2 , 2004, p. 134-137 , doi : 10.1111 / j.1365-2052.2004.01113.x .
  10. ^ R. Bellone, S. Lawson, N. Hunter, S. Archer, E. Bailey: Analysis of a SNP in exon 7 of equine OCA2 and its exclusion as a cause for appaloosa spotting . In: Animal Genetics . tape 37 , no. 5 , 2006, p. 525 , PMID 16978190 .
  11. ↑ a b R. R. Bellone, SA Brooks, L. Sandmeyer, BA Murphy, G. Forsyth, S. Archer, E. Bailey, B. Grahn: Differential gene expression of TRPM1, the potential cause of congenital stationary night blindness and coat spotting patterns (LP) in the Appaloosa horse (Equus caballus) . In: Animal Genetics . tape 179 , no. 4 , 2008, p. 1861-1870 , PMID 18660533 .