Dosage is a very important part of horse sales/breeding. It isn’t the end all be all, but it plays an important role in the breeding and purchase of future stars in horse racing. I’ll walk through everything you need to know about dosage and what it means using California Chrome as a sample horse. You can see it here.
What is it?
When you look at a Stallion Register pdf (or really almost any 5 cross), you’ll see in the top right corner some information about the stallion. So for California Chrome, it looks like this:
So his dosage profile (DP) is (7-9-14-0-0). His dosage index (DI) is 3.29 and his center of distribution (CD) is 0.77. Those numbers don’t mean anything to you yet and that’s fine. Just knowing how to read it will help you sound smart to other horsemen.
Chefs de Race
So where do these numbers come from? That’s where the Chefs de Race comes into play. Chefs de Race are stallions that have had a significant impact on the sport. It’s French for chiefs of racing or masters of the breed. I like the last one more because that’s what we are talking about. The horses that make up the chefs de race aren’t on the list because they were good racehorses. I’m sure most of them were, but that’s not the reason they made the list. They made it on the list because of their superior performance as a stallion.
A full list of them can be found here on the Pedigree Productions site. When you see the full list of sires on the list, you’ll notice they’re broken up into 5 categories. Those categories are their aptitudes.
Aptitudes
There are 5 aptitudes (brilliant, intermediate, classic, solid, professional) and these aptitudes make up the DP. Think of it as a scale, on the far left (brilliant) you have a horse that is pure speed (< 4 furlongs). On the far right (professional) you have a horse that is pure endurance (> 2 miles). When you see a horse’s DP, you can sort of visualize where they’d be on that scale and have a general understanding of where this horse would be best at.
Speed and stamina are inversely related. You can’t have a super-fast horse that has incredible stamina. The faster a horse is, the less stamina it will have.
For instance, California Chrome’s DP is brilliant-7, intermediate-9, classic-14, solid-0, professional-0. So just a general rule of thumb, he would be better at a shorter race compared to a longer race. (More numbers on the left than the right) He would also be better as a middle distance race than a super quick race. (Classic/intermediate is larger than brilliant) And that’s pretty accurate. He was great at 8f-10f for most of his races.
How to determine the DP
Figuring out the DP is a bit overwhelming to do by hand unless you really want to see the chefs de race that are in the pedigree. That might be a good practice, but it seems overkill. So this is mostly just so you understand how it is determined and you’ll have a better understanding of dosage.
For starters, each generation follows a pretty easy point system. If a chef is in the first generation (the dad) then that’s 16. 2nd generation (granddad) 8 points, and it gets split in half until the 4th generation with 2 points. Since some chefs can be in 2 different aptitude groups, then their points are split evenly. 16 –> 8 –> 4 –> 2. So here’s California Chrome’s 4 cross taken from Pedigree Query for an example. You’ll notice any chef has a bracket with a letter or 2 if the horse happens to be a chef de race by their year of birth.
1st generation doesn’t have any chefs de race, so 0 points there. Now the second generation has Pulpit. He’s split into intermediate and classic. So 8 points total split into intermediate and classic.
(0-4-4-0-0) after his 2nd generation.
The 3rd generation (4 pts each) has A.P. Indy and Mr. Prospector in the chefs de race. A.P. is split intermediate and classic and Mr. Prospector is split brilliant and classic.
(2-6-8-0-0) after his 3rd generation.
The 4th generation (2pts each) has Seattle Slew (BC), Mr. Prospector (BC), Caro (IC), Raise a Native (B), Northern Dancer (BC), Danzig (IC) and Sir Ivor (IC). A lot of them are split.
(7-9-14-0-0) after his 4th generation.
I would strongly recommend using a site like Pedigree Query will tell you the DP if you don’t want to do it by hand. Or use the chef de race list on the Pedigree Productions site if you want to do it by hand, here.
Dosage Index
When you look at California Chrome’s DP, you’ll also notice 2 other numbers associated with him. One is DI the other is CD. DI is the dosage index. Dosage Index is the ratio of speed to stamina. This is an important concept because speed and endurance are mutually exclusive. You can’t have both speed and stamina. That’s why Usain Bolt hasn’t won a marathon. The longer the race, the slower a horse (or anything) runs. Think of it as the speed frontier. The fastest horse ever is relative to the distance you are using for your comparison.
So California Chrome’s is 3.29. The bigger the number the more speed the horse should have. Rasmusen, who came up with the current dosage theory, stated that there’s a 4.0 rule where no horse with a DI of 4 or greater would win the Kentucky Derby. So he’s pushing it, where he has quite a bit of speed, but still under that 4.0 line.
I think any horse could win the Derby, but I think it’s incredibly unlikely for a horse with that much speed (or a lack of stamina) to win the race. The reason I say that is hard rules like that will always be broken at some point. Even if it’s a fluke, David will defeat Goliath at least once.
How to find DI on your own
The formula for finding DI is simple. You add the first 2 aptitudes (brilliant and intermediate) and half of the 3rd (classic) and divide it by half of the 3rd and the last 2 aptitudes (solid and professional). This is what that looks like for California Chrome:
(7+9+7) / (7+0+0) = 23/7 =3.29.
Center of Distribution
Think of the center of distribution as a seesaw. On the far left, you have sprint distances (4 furlongs) and the far-right you have long distances (think 18+ furlongs/2+ miles). To me, the positive and negative signs should be swapped, but that’s how (Roman) decided to do it.
Here’s a little table to show a general estimate on where that horse would perform best:
| CD | Distance |
|---|---|
| +2 | 4 furlongs |
| +1 | 7.5 furlongs |
| 0 | 10 furlongs |
| -1 | 13 furlongs |
| -2 | 18 furlongs |
California Chrome’s last number is the Center of Distribution. That’s where we have 0.77. So he would fall somewhere between 7.5 and 10 furlongs. His average winning distance (AWD) was 8.49 which is right between 7.5 and 10.
How do you find CD
The formula for finding CD is pretty simple. It’s [(Brilliant X 2) + Intermediate] – [Solid + (Professional X 2)] / Total points. So for California Chrome, it would look like this:
[(7 X 2) + 9] – [0 + (0 X 2)] / 30 = 23/30 = 0.77.
Why is it important?
The further a horse is away from racing, the more dosage and pedigree matter. If a horse is racing, you look at their conformation and race record more than you do their pedigree. If you have a horse that is a weanling, things like dosage matter more because you are trying to see as much of the picture as possible. A real-world example is we can assume that Usain Bolt’s children will be fast because their dad was fast. Once they start running, we care less about who their dad is and more about their results.
So this is very important when you are furthest from the track. So breeding sheds, a sales ring, a paddock filed with yearlings. That’s when things like dosage matter. You are helping yourself and others make the most informed decision they can with the information that’s available.
How do I use it?
Any single type of pedigree analysis tool should not be the sole method for selecting a horse or selecting a potential mating. The times I think would be most useful for using dosage would be when selecting a potential stallion for a mating. If you’re looking to breed a horse that will be a great endurance racer, look for stallions that have more solid and professional numbers. If you’re looking for a sprinter, look for a stallion that has more brilliant and intermediate numbers.
It would also be useful when you have a horse that’s in training you’re looking for races for it. A trainer could use this for a general understanding of the breeding of the horse and take that into consideration for what types of races you should enter it into. For instance, let’s say you have a horse like Lochsong which has a CD of +2 (a sprinting type of horse). You should think twice before entering it in a 12-furlong race.
Handicappers sometimes use dosage when betting. It makes the most sense for maiden horses or horses that haven’t raced yet. Knowing how to read dosage for those types of races might give you an advantage over other horseplayers.
Where can I learn more about it?
There are a lot of places where you can learn more about this. The modern book on this topic is Dosage: Pedigree and Performance. It’s filled with graphs with dosage information over the past few decades of racing and showing trends in how dosage profiles have been changing over the decades. It’s pretty interesting. He retired from horse racing, so his website is no longer maintained and with it went a lot of good articles, but the book covered just about everything his website had.