We probably all have at least one weigh tape kicking around somewhere, right? Using weigh tapes is a good indication that you consider your horses weight and body condition to be important to their health. This is great, and we will always encourage this awareness. However, there are several factors to consider in using weigh tapes, to avoid being misled by a wildly inaccurate reading. After looking closely at this subject during our pilot study, we have some advice to pass on.
Not all weigh tapes are the same!
We looked at a sample of 6 different (brand new) weigh tapes and lined them up for comparison. These tapes all used the same format, and the weight measurements were based on the widely used formula Heart girth x Heart girth x Length / 11877. The first thing we noticed was a discrepancy in the actual measurement aspect of the tapes. Each tape had a ruler feature in centimetres above (and correlated to) the weight in Kgs. We found two of the tapes to be 1.5cm over, two were 1cm over and one was 0.5cm over. The most accurate tape in terms of basic centimetre measurement was the Equi Life weight tape, which measured correct at the three points we tested.
It’s worth noting here that weigh tapes do not stretch. They are generally vinyl (PVC) coated mesh, and the mesh does not allow any warping under normal conditions. Those without mesh (in our observations) still had an internal ridging component to prevent stretch.
We believe the inaccuracy observed here was simply down to an error in printing. As we found this error in most of the tapes we compared, we now know it is advisable to measure your tape for accuracy before you use it. If your tape is out by any amount, factor this into your calculations…. Or send it back and get a more accurate tape!
Be sure you measure correctly.
It goes without saying, for consistency we need to measure the same point on the horse every time. Though it’s also worth having a friend snap a photo of exactly where you’re holding that tape for comparison next time you measure. Also, be sure you’re using the correct finish point on the tape. Some tapes have an arrow to dictate where you take the reading, and some do not. It may not simply be a case of using the end of the tape, so take a good look to understand how to read the measurement before you use it. For consistency, you should always use the same tape on the same horse.
Don’t rely on the tape reading!
We know from our pilot study that weigh tape readings can be hugely inaccurate. In fact, they are rarely accurate within 20kg either way. So, you shouldn’t rely on your weigh tape reading for medication or health choices. It is wise to have your horse weighed accurately on a weighbridge at least once a year. Twice is best.
We have seen weigh tape readings over 100kg under weighing some horses. This may give owners a false belief that their horses are actually a healthy weight when in fact they are dangerously overweight. The most important aspect to consider when looking for healthy weight in your horse is body fat scoring. Also known as body condition scoring, but as this system identifies fat deposits, we prefer to call it what it is!
There are two systems generally used for body fat scoring. The 5-point and 9-point scale. Both work on the same principle in observing and palpating fat cover over specific areas to reach an overall score on the scale. Body fat (condition) scoring is very important for our horse’s health, and it’s something we should always do when the weigh tape comes out.
We know that much of the research behind the commonly used formula for weigh tapes (heart girth x Heart girth x Length / 11877) was conducted with Thoroughbred horses. We think this factor together with the variety in body fat scores may contribute to inaccuracies in weigh tape readings.
Some vets suggest adapting the common formula where the body fat score falls above or below the ideal median. For example, If your horse has a body condition score (On the 5-point scale) of less than 2.5 use 12265 instead of 11877. If they have a body condition score above 2.5 use 11706.
This points towards a clear need for further research. Perhaps weigh tapes developed for types of horse could be more accurate?
Overall using a weigh tape is good practice, and it will certainly help you to identify weight loss or weight gain in your horse. However, it doesn’t tell you how healthy your horse is, and you shouldn’t rely on the weigh tape reading in comparison to the ideal weight for your horses breed and height.
Investing in the service of a professional who can bring out a weighbridge is by far the ideal scenario. This can complement your use of the weigh tape and help you understand how to use it for more accuracy. During a weighbridge assessment, your horse will also be body fat/condition scored, and this will be the most useful information you can gain for the health and wellbeing of your horse. With a regular yearly or twice-yearly weigh-in, you can learn how far out your weigh tape is, and where your horse needs to be for an ideal body score.
There will be a service near you! Check out these links for more information