Featured this month (October 1997) is a pattern of streaking seen only on a portion of the body, that resembles the brindle pattern. This pattern is referred to in earlier Spanish literature as "chorreado". We will also expound on the "gateado barcino" color, since a translation of Solanet's book just became available in Sept 1997, which was not available when we featured the "gateado barcino" pattern earlier in March 1997.
Emilio Solanet published an article in 1930 in the Journal of Heredity 21:451 about "the Criollo horse of South America". He also lectured and wrote books and articles in the 1940's, and published a book called Pelajes Criollos in 1955, about colors of Criollo horses in Argentina. The book is written in Spanish. In September 1977 Mrs Pilar Massaguer most kindly furnished me with a complete translation of Pelajes Criollos. Following are portions of her translation regarding our featured topic this month. On page 116, Solanet makes a mention of "chorreado" as looking "like if a liquid had been poured over him. It can happen in a part or the whole body. It is not the same as the "atigrado" or "barcino" since the latter has the stripes similar to the tiger's." Solanet seems to make a clear distinction between the two different types of striping ("chorreado" and "barcino"), and does not consider them to be the same, but he has no illustration in his book of what he is calling "chorreado", only of the "gateado barcino" color on page 51 (see below - left). His description of "chorreado", however, is similar to the way I have often heard people describe brindles they have seen. Of particular note is his observation that it can happen on only a part of the body. Also, according to him, a "gateado barcino" is only a dun factor horse with maximum dun factor markings, and would not be the equivalent of what we would call a "brindle dun" today. However, as discussed in March, others have thought the sinuous nature of the striping shown in his illustration resembled the Russian brindle (see below - right).
J.A. Lusis wrote an article called "Striping Patterns in Domestic Horses" that was published in Genetica vol.23, 1942. He details a Russian cab horse from around the 1800's, that was preserved and put in the Zoological Museum in Leningrad (picture above right). He says "The striping of the horse exhibited in the Zoological Museum of the Academy of Sciences very closely resembles the striping found in many breeds of cattle and in dogs and known as the "brindling pattern"... Of examples of striped horses described in the literature the closest to our third type of striping (brindle) is the case of a striped colt of Darwin's own breeding (see Darwin, loc.cit.,p.72)." He describes the colt in detail. In summary it appears that Darwin's colt had what we would now call dun factor markings, plus a brindle looking pattern on the body. However, Lusis says he would classify Darwin's colt with dun factor types of horses. This is probably what Solanet also did in some horses he called "gateado barcino". Some of them could very well have been combinations of "brindle" and "dun", but were instead considered to be some sort of variation of maximum dun factor markings.
Odriozola (author of A Los Colores Del Caballo in 1951) has included in his book between pages 338 and 339 a photo of the same Russian stuffed museum-horse as seen in the Lusis article, but with the following caption in Spanish: "Pelajo (coat color) chorreado". He also makes reference to "chorreado" as the type of coat seen in dogs and cattle. Thus, for Odriozola, "chorreado" is equivalent to what Lusis was calling "brindle". Also of interest, Odriozola says in his book on page 38, "If dun factor markings represent markings constituted by hairs darker than the color of the background, then the opposite happens in the little markings of "safran" color, so to say "lighter markings", that Lady Wentworth (1945) said to have seen in a bay mare, that she said would correspond to the color called "amik" by the Arabs. Perhaps this strange/rare coloration is related to the bay brindle of dark red and yellowish tones, that is preserved and stuffed in the Science Academy Museum of Leningrad ..."
Neither Solanet or Odriozola make mention of whether "chorreado" marks can appear in white hair, or whether they just appear in darker colored hair. Above is a picture of a Bavarian Warmblood filly with white streaking on one side only, that to me resembles brindle streaking. In D. Phillip Sponenberg's latest book from 1996, Equine Color Genetics he also has a picture of this filly in Fig.8.65 on page 113. He says "Most horses with odd white striping...are the result of chance errors that occur in the development of the pigment system of the embryo. These horses will not reproduce these stripes... White or roan striping is probably biologically different than brindling, which is black striping, even though the patterns appear superficially similar."
The picture at the top right of the beginning of this article is of a Thoroughbred I saw at a show, with a "chorreado" or "brindle" like pattern of partial streaking of slightly longer and darker hair over the hindquarter only. The owner said her trainer told her she had seen other Thoroughbreds with similar marks. In the slideshow is a picture of a Thoroughbred owned by Haley Clark. He is going gray, but has brindle like streaking on parts of his body. However, it is hard to tell if the streaks are in white, black, or both black and white hair because of the influence of the gray gene. I have also had a report of a Thoroughbred that looked as though white paint had been poured over her back and had run down her sides. This description matches Solanet's description of "chorreado", which Odriozola likens to the "brindle" Russian horse. Thus, it seems that in Thoroughbreds, a "brindle" looking pattern can appear in either dark or white hair.
Most people I talked to when I was just beginning my work with brindles in 1989, had thought brindle and partial streaking patterns were due to "sports", random mutations, or coat developmental abnormalities, and as such were probably not inheritable, especially since the pattern had not seemed reproducable in the past. However, I have now been able to reproduce the brindle pattern, so perhaps "chorreado" and partial streaks that resemble brindling will also turn out to be inheritable. I feel that there is a good chance this partial streaking may turn out to be a minimum expression of the "brindle" pattern, much as brindle in dogs and cattle can range from slightly to profusely marked animals. However, it may turn out that these partially streaked "chorreado" patterns are indeed non-inheritable coat developmental patterns. At this time we can only speculate, as there is not much information available on these patterns yet. If you know of any horses exhibiting similar partially streaked patterns, please contact me.