Phenotype Classifications

Phenotype is the expression of physical traits as determined by our measurement data. EQUIX uses a dozen Phenotypes to show the relationship of a horse’s Power, Stride, and Body Weight (or Trunk Size.) Phenotypes are used as a rough guide to quality, distance potential, and to project breeding consistency in both mares and stallions.

Power - muscling, size and leverage of the hindquarters and hind leg.
Stride - balance of front to back legs and the leg and cannon lengths.
Body Weight - length and breadth of the trunk, giving adequate body weight to process energy.

As these proportions vary, the horse adapts to speed and distance. Variations within each Type occur when the horse's efficiency of motion and heart capacity come into play. There are good and bad horses within each Phenotype.

Phenotype Descriptions

Type I: The Power and Stride are ideally balanced to the Body Weight. Type I horses generally have very good quality and pass on this substance to their offspring. As Sires and Dams, many have been breed shapers, and they can be very good racehorses.

Type IIS: More Stride traits relative to their Power and Body Weight. This Type is ofter our elite distance runner with enough Power for versatility.

Type S1: Also run on Stride Rhythm, with slightly less Power and/or Body Weight in relative terms. Horses of this Type need excellent stride efficiency for optimum performance. Less commonly seen in the breed than Phenotype IIS.

Type S2: Like Type S1, they run on Stride Rhythm, needing excellent stride efficiency for optimum performance. A relatively rare Phenotype, they have less Power than Type S1.

Type S3: Also a rare Phenotype, they are the ultimate Stride horse and some have a one-run style.

Type IIP: The most balanced of the Power types, these horses can run short or long depending on their overall biomechanics. They can also be consistent breeders, both as Sires and as Broodmares.

Type P1: With a little more Power based on their Stride and Body Weight, we often see sprinter/milers here but if the stride is very efficient they can go longer.

Type P: Lots of Power to the point of being brilliantly fast but they may not stay sound for long.

Type E1:The E-types (E stands for Even) are lighter in Body Weight relative to their Stride and Power. A very common Type, they can be very good racehorses going short or long and some can be very good producers when selectively bred.

Type E: The most common Phenotype in the population is characterized by having a light trunk relative to Power (muscling) and Stride (leg length). E-types with high BME Scores can be very good racehorses. In breeding, though, this is one of the more inconsistent producers of all the Phenotypes. The lack of adequate body weight is perpetuated through both the mares and the stallions.

Too much Body Weight (Trunk Size) for their other traits. The extra weight can reduce performance and soundness. This is not a common Type, but they can be decent broodmares with the right stallions; they add substance and quality to their offspring.

EQUIX CARDIO CAPACITY SCORES

EQUIX uses ultrasound to scan the left chamber of the heart. This is the output valve. We store several consistent beats of the heart and take measurements when the chamber is in the expanded state (diastolic) and then when the chamber contracts (systolic). From this we calculate Stroke Volume, or how much blood is being pumped per beat. We also measure the thickness of the heart wall muscling and observe and note the pace, timing, and function of the chamber.

The data derived is computed with a set of body measurements, and an EF Score given for each horse is based on the horse’s size, sex, exact age, and level of fitness.

Average EF Scores:
Yearling colts - 6.5 to 6.6
Yearling fillies - 6.3 to 6.4
Two-year-old colts - 7.0
Two-year-old fillies - 6.8 to 6.9

Average, in this sense, is not "mediocre". It means that the oxygen delivery potential of the heart "fits" that particular horse's body size and structure.

Many horses with average EF Scores have suitable oxygen delivery for racing at most distances (based upon their onw biomechanical potential). However, horses who have Above-Average heart capacity gain oxygen delivery potential when racing at distances over a mile, particularly colts. When excellent wals, a naturally slow pace, and good function are present, these traits increase the athleticism of that particular heart and there is a greather chance for a high performance level.

Our 26 years of Cardio data support this, and we use this vast database to give an overall rating on each heart. We continually track the percentage of stakes winners and stakes-placed horses within each EF Score category, plus average earnings, average winning distance, and speed indexes.

Sprinters often race well with average and even slightly below-average heart capacity, especially if athletic traits are present. A sprinter's oxygen delivery needs begin right out of the starting gate when fast early fractions are often key to winning these races. An average or smaller heart with strong walls has the timing and function to deliver oxygen quickly to the muscles.

For distance racing, a larger heart's oxygen delivery potential kicks in as the race progresses to a strong stretch drive and can stave off lactic acid buildup in fatiguing muscles more readily.

EQUIX also uses Spleen Volume measurements in its endurance potential evaluations. The spleen serves as the red blood cell reservoir from which the horse draws on for extra oxygen delivery under exertion. In racing, this means the ability to meet and exceed the oxygen delivery demands of a strong finish to the wire.

EQUIX provides Cardio Reports to clients and it is part of our biomechanical Racing Analysis. We take 38 body measurements of the horse, apply growth rates, and calculate the key structural areas of each horse that reflect racing efficiency and balance. These areas include power, stride balance, leverage, body weight, extension, and motion efficiency indicators. Adding the Cardio results to this report helps us "distance" the horse, and we make sure that the heart suits the structural capabilities of the horse.