Hay everyone!

I hope you guys remember some of that research I talked about in my last blog! Don’t worry if you need a refresher, go ahead and check out the post about Rutgers Giving Days and come right back here.

Ready to hear some more? I had the opportunity to chat with the Rutgers Equine Science Center’s very own postdoctoral associate, Dr. Alisa Herbst, about what she’s been cooking up. Dr. Herbst has been doing a lot of work to make sure the voices of elderly horses and their owners are heard. She has also developed a unique system for evaluating muscle mass in horses, and most of her current work is related to further refining this system.

Let’s dive right in!


Lord Nelson (LN): What is MASS and what is it used for?

Dr. Alisa Herbst (Dr. H): MASS is an abbreviation for “Muscle Atrophy Scoring System,” and that’s really what it is. It’s a system that’s similar to the body condition scoring system for horses, developed by Henneke. It evaluates, however, not fat mass like the Body Condition Scoring [BCS] system, but  muscle mass, and any reductions in muscle mass, also called muscle atrophy. Anything that we would consider clinically important muscle atrophy in a regular horse should be detectable with the Muscle Atrophy Scoring System. It is important to note, however, that the Muscle Atrophy Scoring System doesn’t really evaluate minor muscle atrophy in super athletic horses with superior muscle mass.


LN: Is your goal for the average horse owner to be able to learn how to do this?

Dr. H: The average horse user should, along with body condition scoring, check the muscle mass of their horses. As I said, the BCS looks at fat mass, not muscle mass. There are certain circumstances under which a horse might lose fat mass, but not muscle mass, and vice versa. So, it’s important to look at both at the same time. If you do this as a horse owner with your veterinarian for an annual checkup that’s probably not frequent enough. I would recommend doing it monthly or even twice a month.


LN: Is there a specific type of horse that would benefit from this?

Dr. H: We know that elderly horses, for example, are experiencing an age-related loss of muscle mass. On top of this natural age-related decline in muscle mass, elderly horses might also experience muscle atrophy connected to medical conditions such as pituitary pars intermedia dysfunction, also called Cushing’s disease. For example, we see that about 50% of the horses with Cushing’s also develop muscle atrophy, particularly in the back area.

There are many other conditions that can lead to muscle atrophy in horses. Problems with dentition, for example, can lead to reduced food consumption and subsequent muscle loss. Injuries and conditions such as osteoarthritis, can cause a horse to move less, which can result in muscle atrophy as well. EPM, Equine Protozoal Myeloencephalitis, is another condition which can present with muscle atrophy. And there are many, many more, and I couldn’t even begin to list all of them.


LN: So, you would use this to help diagnose one of those conditions.

Dr. H: Yes. That’s really the ultimate goal, to make sure the horses are in good health and welfare, as well as to help diagnose certain conditions. The welfare aspect is another important point. When horses have particularly low muscle mass, they are unable to get up after laying down or avoid a horse that’s charging them, situations like that.

There’s also a performance component in all of this. A lot of people who own horses with low muscle mass say that they feel like their horse doesn’t perform as well as it used to and that this is due to the low muscle mass. But we don’t have a lot of data on what muscle atrophy in a given location in a horse’s body means for what kind of performance. In other words, the relationship between the degree of muscle atrophy in a certain area of the horse’s body and the horse’s ability to perform a certain task is not very clear.


LN: In the future, would you hope to take this further and look more at performance horses?

Dr. H: We could do that. Although that’s not necessarily what I had in mind so far. I mainly want to make sure that one can easily and reliably detect muscle atrophy in horses and then take a closer look and determine why this is happening and what we can do about it. An objective monitoring of changes in muscle mass was another goal that I, and the group who helped me develop the system, hoped to achieve. It is also possible that the MASS might be used to help determine treatment success of certain conditions at some point in the future. The next steps are to validate the system further to ensure reliability.


LN: When did you initially start developing this?

Dr. H: Oh, that’s many years back, I can’t even remember the exact year!

It actually took us quite a while to come up with the system. It’s a combination of multiple previously existing scoring systems. One of them is the BCS, and that is what’s so special about the MASS. Components of the BCS are included to allow us to differentiate between muscle and fat mass when using the MASS to rate muscle atrophy in horses. Other muscle condition scoring systems for horses are not able to do that. It really stands out from other systems because of that. There’s also a cat and a dog muscle condition scoring system, which is very similar in structure to our MASS. There are four categories: no atrophy, mild atrophy, moderate atrophy, and severe atrophy, as well as criteria that describe how the dog’s or cat’s muscle would look and feel like, just like we do with the MASS for horses.

And then there is yet another scoring system that was developed before ours specific to performance horses to a degree. They developed it for dressage horses specifically, and we used that system as a template, but simplified the terminology and collapsed some of the scoring regions just to make it more user friendly for the average horse owner. This also served to make scoring a lot faster because for that very detailed scoring system, you need a lot of technical knowledge on anatomy in horses and it takes a significant amount of time because there are so many regions that you’re evaluating. Yet, for performance dressage horses this is really a great system.


LN: What was your inspiration for developing this system?

Dr. H: What happened was that for my dissertation, we were interested in researching the relationship between age related muscle loss and changes in immune function. And to do that, we needed a way to measure muscle loss in horses. I looked around and couldn’t find any scoring system at the time that would allow us to do that quickly and reliably, and to be able to apply it to horses in the field. We ended up just developing one because there was this need that we saw, and many other people saw it as well, because we have the BCS for fat, but nothing equivalent for muscle. And I know that a lot of people were just using that body condition scoring system as a surrogate for muscle scoring, and it’s not really accurate.


LN: That’s really interesting! Are there any quantitative techniques or tools that you could have used too?

Dr. H: Yes, ultrasound techniques can be used. We actually used an ultrasound technique along the way when we tested the MASS for the first time, just as a way of validating the MASS. Unfortunately, we had some issues with that technique and thus are using a slightly different one in future validation studies.

We had also used some other measurements in our validation study, for example, the belly girth, neck circumference, etc. These measurements worked better. There are also other techniques that can be used such as bioimpedance spectroscopy, deuterium oxide dilution and a few more.


LN: Wow, it seems that you developed this system almost accidentally! You saw this need as a result of another project.

Dr. H: Yes! We absolutely saw a huge need for it. While I needed it for my dissertation, the equine industry and community needed it as well. In fact, the system has been advertised by a couple of lay publications in the US and by a nutrition company in the UK. They even created an online version of the MASS so that owners can quickly evaluate each part of their horse using something like an app.


LN: I heard you’re working on a project related to MASS with some current undergraduate students at Rutgers. What’s that all about?

Dr. H: Yes! Now we need to further validate the system. When we did the initial validation, the two people who scored with me were trained on how to use the scoring system before they used it. The average horse owner currently doesn’t receive training, they just take the article from the Internet and start scoring their horse.

To see if people do need training, we’re doing this current study where the raters are not trained before. We compare their scores to my scores, and we compare their scores among each other. After that we’re adding a second layer to this where we’re also looking at the score consistency over time. We’re rating every horse three times, which we didn’t do in the initial validation study. The first validation study really showed great interrater reliability for those trained individuals. If we now find in this study that the people should be trained, we will be working on creating instructional videos that should help people understand how to score a horse properly.


LN: Although you haven’t finished this study, how would you plan to expand on this work? Do you have any future steps in mind?

Dr. H: Yes, as part of an upcoming study we will further validate the system, but this time for the systems accuracy rather than reliability.


LN: Thank you Dr. Herbst! I learned a lot about the research you’re working on, and I’m sure our readers will be just as excited to hear about it. Do you have anything else you would like to leave our readers with?

Dr. H: It was my pleasure! Developing the system and now validating it is really a big team effort, and I just wanted to give a shoutout to everybody involved in this project, which we hope will improve the health and welfare of horses around the globe.


I hope you learned just as much as I did from this interview! Our friends at the ESC always have some cool stuff they’re working on. I’ll have to check back in with Dr. Herbst later to see what the results of her study are. Don’t worry, I’ll be sure to share them with you too!

Until next time.

Your friend,

Lord Nelson

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