Bend Or, Birdcatcher, Tetrarch: Guinness' Weird Color Genetics

Can you find the spots?
Photo by Alli's talented husband (StitzPics)

Thoroughbred breeding is fascinating to me, especially as it makes tracking weird color mutations easy through generations. Take Guinness for example...

Pig's Breeding, expand for detail, click for interactive.
Note:total earnings are not correct here, as his winnings abroad and in US are not combined.

If you look close, you may notice that Pig's great-grandsire on both sides was Never Bend (aside, I love Pig's breeding), whose lineage goes back to The Tetrarch. At this point, you may be asking yourself. Who is The Tetrarch? Why do I care? Valid questions...

I think you can see why you care...

The Tetrarch was a sprinter bred in 1911. He was out of a Bend Or mare, and by Roi Herode, a turf horse. Renowned as much for his blazing speed as for his outlandish coloring, The Tetrarch was extremely popular as a racehorse. After an undefeated year in 1913, "The Spotted Wonder" was retired in his second year of racing due to injury. Time in the breeding shed was also short lived for The Tetrarch, as both he and mare owners seemed equally uninterested. He sired only 130 foals.

Despite his short career, The Tetrarch's ability to pass on his brilliant speed led him to be named "Leading Sire" in the UK. His daughter, Mumatz Mahal, is known as one of the most influential broodmares in the breed. It is through her we get Never Bend, and further down the line my lovely Logic Lane.

Besides ridiculous speed, The Tetrarch was known for passing down his strange coloring. His coat displays a combination of Bend Or spots (named for his sire) and Chubari spots. He may also have exhibited Birdcatcher spots, as his lineage also traces back to that horse. The Tetrarch's gray coat lent him even more of a wild look, adding to his popularity.

While it's rare to find a horse with the outrageous spotting of The Tetrarch today, these types of spots are not uncommon in the thoroughbred breed. They are especially common in chestnuts and grays. As the thoroughbred has been used in the breeding programs of many other breeds, the spots are not just found in the thoroughbred. Arabians, warmbloods, and quarter horses also commonly display the markings.

I'm going to go into more detail about these spotting varieties, as well as show examples of how they present on Pig.

Birdcatcher Spots
What they are: Small white spots, usually not bigger than an inch.
Normal presentation: Randomly spread, and may appear or disappear as the horse ages. Not related to skin damage-- not scaring. May be clustered densely, or present as single spots. Skin under spots is black, unlike other white markings.

The spot on his shoulder is the brightest and longest-lasting spot.
Photo by PICSOFYOU.COM

How they present on Guinness: Pig has three fairly stable Birdcatcher spots.

1. The brightest is on his right shoulder. Though very small, the white hairs of this spot are dense, making the marking pop out in photos. This spot wasn't always as bright as it is today, it has grown brighter as Pig has aged.
2. The next most stable spot is on Pig's right buttock, near the tail. This spot is almost an inch in diameter, but very faint. The white hairs are quite spread out. This spot hasn't changed in appearance much over the years.
3. The third spot is on Pig's barrel, near the whorled hair around the stifle. It is also about an inch in diameter. This spot's brightness varies on the time of year. During the winter it is most prominent, but Pig's summer coat sheds out quite a bit in this area making the spot difficult to see.

Haunch spot visible on upper part of buttock, very near the tail (hint, follow the line of my dressage whip). This one goes fainter in the summer. His shoulder spot is also visible. Spots more easily seen in below photos are invisible due to summer coat bleaching out/his movement.

Shoulder spot, whorl spot, and haunch spot visible, though whorl spot is faint. Photo from late summer of 2010.

Same spots, from late spring 2011. Note much more prominent whorl spot.

Besides the stable spots, Pig has other Birdcatcher spots that appear quite randomly. This past fall he spotted fairly intensely around his flank. Interestingly, the spotting was on both sides, though less intensely on the right.

The big but faint spot on the upper-right of the whorled hair. Smaller, very impermanent, spots are spread throughout the area.

These spots only lasted for around two weeks before they disappeared with the full winter coat. While these were new this year, in other years I have seen single small temporary spots appear on Pig's shoulders and haunches. There does not seem to be a predictive cause for the increase in spotting.

These spots are very rare for him. They only appear for a week or two.

Tetrarch/Chubari Spots
What they are: These are large, typically egg-shaped, white spots.
Normal presentation: Chubari/ Tetrarch spots occur on gray horses, for the most part. As the gray coat fades, the spots become less visible. The skin under these spots stays black, as with Birdcatcher spots, not white as with regular white markings. They often are presented spread widely across a horse's body.
How they present on Guinness: They do not present on Guinness, as he is not gray.

Bend Or Spots
What they are: Bend Or spots are dark (sometimes called "sooty") spots, typically seen in chestnuts. These are named after the chestnut stallion Bend Or, who exhibited such markings.
Normal presentation: These spots typically appear after the horse is a few years old, rather than at birth. They may range from slightly darker than the coat color to nearly black. The size varies dramatically, though most often a few inches in diameter.

Bend Or spot on the right butt cheek, just by the tail.
Photo by Alli's talented husband (StitzPics)

How they present on Guinness: If you had asked me last year if Pig had Bend Or spots, I'd have said no. But this spring, something crazy happened. First, a fairly large one (3" long) popped out on his right buttock, just near his tail. At first, I thought he had a big poop stain. After three days of baths didn't budge the thing, the fact that the mark could be a Bend Or spot started to occur to me. That's when I started looking more closely at the rest of him.

I found another, slightly smaller, spot was also visible about 6 inches down and a few inches to the right of the first big spot. Then I discovered a mess of tiny black spots in the whorl of his right flank. These tiny spots vanished after about a month, but the other smaller spot is still faintly visible. The larger spot is going strong, seeming to get brighter as summer sets in. I'm interested to see how these progress.

Tiny Bend Or spots, and also the larger Birdcatcher spot. This is the same area as pictured in the Birdcatcher spot section, but in spring rather than fall.

Mottled Skin
Pig's weirdest "marking" is his mottled skin. As far as I can tell in my research, mottled skin is not something known of in the lines of The Tetrarch family. It is also not common enough in thoroughbreds to be mentioned. There are only a few instances where mottled skin is known to appear.

1. Appaloosas: The most common example of mottled skin. 
2. Grays: Often seen around the muzzles and eyes. Seems to be more common in Iberian breeds. May be related to the gray gene.
3. Champagne mutations: Common in apricot colors, especially. It is not known why.

This mottling occurs all over his body, but is easiest to photograph on his chest.

Pig's mottled skin is not limited to the delicate skin around his muzzle and eyes, though it does appear there. Instead it is widely spread across his whole body. Difficult to see most of the time, it is easiest to view when he is wet after being fully body clipped. This mottling has been constant since I have owned him.

I have no idea why he exhibits this weird skin pattern. He absolutely is not champagne, and the gene does not run in either side of his family. He does have a tiny amount of gray genes that run through his mare line, so I wonder if it could come from that. Though the gray gene is dominant, so he definitely doesn't have it. It may be that this mottling is more common than I realize, but Pig's thin coat makes it easier to see. If you have any ideas about this, please reach out!

The best time to see his mottled skin is when he is wet from a post-clipping bath.

Equine color genetics fascinate me, and these weird mutations especially! Does your horse exhibit any of these classic spotting mutations? Can you track it through the breeding? Please share!