Posted by on Jun 29, 2017

Comparison of  Heart Rate in a Horse Using Tad Coffin Performance Saddles and a Steuben Saddle

Prepared by Melissa Holland, DVM, DACVA June, 2017

540-461-0260

Saddlestudyquestions@gmail.com

 

Background

The following study of three saddles was undertaken based on expansion of an existing model used by the designer/manufacturer of the Tad Coffin saddles.  Two saddle models were utilized, the A5 and the TC2, both close contact saddles designed for use in hunter/jumpers.  In the data attached these saddles are referred to with the symbols TC.  The third saddle was a Steuben, all -purpose saddle with a deeper seat, originally purchased for the fit of the tree, then classified by the manufacturer as a narrow tree.

Based on the designer’s preliminary data on equine heart rate while wearing the TC saddles, a small study was made comparing resting heart rates between the two saddle types.  The horse was then ridden in one or the other saddle for a 30 minute period.  This procedure was followed for a minimum of 5 consecutive days for each saddle.

Subject and Materials

Horse – 15 year-old thoroughbred gelding; 17 hands, with typically prominent withers; show hunter; sound cardiovascular, respiratory and musculoskeletal systems prior to and throughout the experiment.

Observer/experimenter – Horse’s regular rider, a retired equine veterinarian with background in physiology and pharmacology specific to anesthesia, trained and certified in animal chiropractic with several years of practical experience in this discipline with the horse.

Saddles –

  1. Tad Coffin Performance Saddle A5 and TC2.
  2. A Steuben all-purpose saddle with narrow tree width selected from a number of saddles for this particular horse. This saddle is the observer’s normal, everyday saddle.

Girth – Professionals Choice nylon backed with neoprene panel, elasticized on both buckle ends (this horse’s everyday girth)

Padding – Standard, contoured cotton quilt under pad and a Mattes fleece half pad (this horse’s usual padding)

 

 

Experiment

Heart rate (HR) was measured by digital palpation of the left facial artery as it crosses the medial surface of the mandible.  The study was begun each day in the horse’s stall.  The horse was not tied or cross tied at any time but allowed to move freely around the stall.  The horse was groomed as usual in preparation for the day’s ride.  Heart rate was measured, noted as elapsed time zero (0) in the attached data, and then the saddle was applied and positioned as normal for this horse.  The girth was applied so that a finger was easily slipped between the horse’s rib cage and the girth.  Heart rate was measured thereafter every 5 minutes and recorded for a total of 20 minutes.

The horse was then ridden for a total of thirty (30) minutes.  For the first 10 minutes, the horse was allowed to walk on a loose rein with contact gradually taken for the latter half of this warm up period.  The last 20 minutes consisted of trotting and cantering.  Occasionally low verticals were jumped.  At the end of the 20 minutes, the rider brought the horse to a walk, dismounted immediately and took the first heart rate measurement.  This point is noted as elapsed time 50 minutes in the data chart and table attached.  At elapsed time 52 minutes, 55 minutes, 60 minutes, etc., the heart rate was measured.  At approximately elapsed time 55 minutes, the saddle was removed.  At approximately elapsed time 60 minutes, the horse was given a bath with tepid water to assist cooling (as usual post-work for this horse during warm weather).   Heart rate was measured for a minimum of 60 minutes after the end of the horse’s work (last measurement at elapsed time 110 minutes).

Data was gathered over a period of five riding days for the Steuben saddle and eight (8) riding days for the Tad Coffin (TC) saddles.  The median heart rate for each elapsed time period from 0 to 110 minutes was compared.

Results

As can be seen in the table and chart that follow, the horse’s median resting heart rate was consistently 36 bpm at time zero.  The application of both the TC2 and the A5 saddles produced a significant reduction in heart rate.  The heart rate dropped approximately 30% by the first reading at 5 minutes after saddle application and remained at this level throughout the 20 minute pre-ride period.  The Steuben saddle produced no change in heart rate pre-ride.

Return to resting heart rate, 36 bpm for this horse, occurred on average, within 3 minutes post ride for the Tad Coffin saddles.  For the Steuben saddle, 11.7 minutes was required for return to the horse’s resting heart rate.  Interestingly, the horse’s heart rate continued to drop below the resting rate for the Tad Coffin saddles and consistently stabilized at the pre-ride- with -saddle -on rate of 28 bpm.  The rate remained at this level for at least one hour (60 minutes) post ride.   This phenomenon did not occur with the Steuben saddle.

Other Observations

This experiment began by determining the effect on heart rate, if any, between either the Tad Coffin A5 or TC2 and the Steuben saddle.  The Tad Coffin saddles produced a significant reduction in heart rate and this effect was prolonged.  This suggests that repetitions of this study should provide that the order of saddle placement should be such that the Tad Coffin saddle is the second saddle tested.  In other words, apply the non-Tad Coffin saddle first to reduce the possibility that the horse’s resting heart rate will be inaccurate.

The effect on the horse’s heart rate recovery produced by variations in ambient temperature and humidity could not be isolated in this study.   Nor could the influence of respiration be easily correlated with changes in heart rate.  Respiratory rate post exercise was elevated, and even more so as humidity, in particular, climbed.  These findings would be expected intuitively, but there was no consistent correlation with heart rate.  Post exercise cooling was assisted by hosing with tepid, not cold, water.  The application of water to the skin areas supplied by the great veins of the neck and legs and then to the entire skin surface is a common method used to speed cooling in horses post exercise as is application of circulating air, usually supplied with fans.  Fans were not used for cooling in this study.

In general, the horse was alert during work, though he seemed almost sedated in the stall.  This is a quiet individual under most circumstances, so this latter observation may have nothing to do with the effect of a saddle.   Interesting side note:  this horse does not love horse showing.   He seemed much less ‘worried’ about the whole horse show experience after riding in the TC A5 each day.  Real or imagined?  See discussion on cortisol below.

Measurements and trends with the two Tad Coffin saddles were fundamentally similar.  The TC2 was first evaluated.  The rider returned to the Steuben and measured heart rate for 5 rides.  Then measurements were made with the A5 saddle.  Riding in and out of these saddles at these weekly intervals was subjectively interesting.   The horse’s way of going in the TC saddle seemed to ‘hang over’ into the time spent riding in the Steuben (say around 4 rides).  Once returned to the second TC saddle, the A5, there was a period of about 2 days when the horse seemed to be ‘testing or experimenting’ with the saddle change.  Again, on about ride number 4, he settled back into the TC frame and way of going (difficult to describe other than to say better balanced and more efficient self-carriage in all gaits; the sense that the rider must remember not to over-ride.  Communication is more efficient?)

Suggestions for Further Study

The mechanism for the heart rate changes and differences in recovery to resting heart rate post exercise produced by the Tad Coffin saddles is unknown.  The recovery to resting heart rate after exercise was significantly faster with the Tad Coffin saddles  (median 3 minutes) than with the Steuben saddle (median 11.7 minutes).    Even more curious is the initial drop in heart rate produced by the Coffin saddles pre-exercise and the persistent lower than resting heart rate eventually reached post-exercise.

Further monitoring of the post-exercise heart rate would be helpful.  How long does this ‘sub-resting’ heart rate last?  On two occasions where measurements were made, the heart rate remained at this level for at least two hours post exercise in the TC saddle.  This effect was also evident at competition (horse show).   The heart rate and heart rate recovery results were similar to those observed ‘at home’.

It would be interesting to measure cortisol levels.  Cortisol is the stress hormone.   Both heart rate and cortisol levels are affected by the balance between sympathetic and parasympathetic nervous system function.  Sympathetic is the fight or flight system.  Heart rate goes up.  Parasympathetic acts as a counterweight to the sympathetic system.    Heart rate comes down.  One could measure levels of resting cortisol and heart rate in the horse in the pre-exercise condition.  Measure resting cortisol and heart rate, then after 20 minutes in the non-TC  saddle, measure again.   Repeat for several days.  Then do the same experiment for the TC saddle.   Does the heart rate decrease with the TC saddle correspond with a change in blood cortisol levels?   This might be a tricky study to do.  Baseline blood cortisol levels would have to be well documented in the study subjects such that any changes which accompanied the application of a saddle would be measurable without too much artifact.  In order to minimize the effect of outside influence on the horse’s cortisol levels, observers would most appropriately be the subject horse’s regular rider and the horse should be in a familiar environment with regular routine.

As an aside, the rider feels the sensation that the horse seems more comfortable and willing in his work in the TC saddles.  Is this real or imagined?   Is it just because the rider is in better communication with the horse through this saddle that the horse is more comfortable at work?  Or is it something physiologic as well?  No doubt, this is a system with many moving parts, subject to the influence of many variables.

Based on the results of the study described herein, other studies that would be of interest include:

  1. A study comparing effect on heart rate by saddles where the saddle design/manufacturer is unknown to the observer and where the saddles are substantially similar in appearance
  2. A study measuring heart rate while stimulating acupuncture points along the bladder meridian where saddles typically are positioned on the horse’s back

 

Summary

The effect on heart rate produced by saddles designed by Tad Coffin (TC) Performance Saddles and a Steuben saddle was measured in a fit, 15 year old thoroughbred gelding both at rest and after 30 minutes of exercise at the walk, trot and canter.  The TC saddles produced a 30% reduction in heart rate at rest and a return to resting heart rate (36 bpm) post exercise in significantly less time – 3 minutes for the TC saddles vs. 11.7 minutes for the Steuben saddle.  Further reduction in heart rate below resting level post-exercise was produced by the TC saddles, but not by the Steuben saddle.  Application of the Steuben saddle did not produce a reduction in heart rate at rest nor did this saddle produce a post-exercise reduction in heart rate below resting heart rate.

Notes on the table and chart

The accompanying chart has a gap between elapsed time 20 minutes and 50 minutes.  This gap corresponds to the 30 minutes of riding where measurements could not be taken.  The first measurement is at the end of the ride.  The total elapsed time at this point is 50 minutes.

The pale green dot just above 35 on the heart rate axis is the resting heart rate pre saddle application with each saddle.  This horse’s resting heart rate of 36 bpm is consistent from day to day.   The heart rate decrease to 28 bpm with the TC saddles is noted by the red boxes.   Heart rate in bpm for the Steuben measurements is represented by the purple X’s.

Heart rate measurements for each time point in the table are the median rates in bpm for the 5 days spent riding in the Steuben saddle (ST) and 8 total days in either the TC2 or the A5.