In this post I want to address the common myth that growth rings indicate instances of laminitis. While they can indicate laminitis, it is rare that they do, and more importantly they are a roadmap to understanding the connection of the hoof wall to the coffin bone via the lamina.
I have been a barefoot trimmer for 11 years and have been teaching horse owners to trim their own horses for 6 years. Throughout my career I have seen both laminitic and foundered horses and I have been able to successfully rehabilitate many of them. The most important part of the rehab process is understanding the condition that you are dealing with.
Horse owners, vets, and farriers often use the terms laminitis and founder interchangeably, but it is my personal mission to educate people on the correct use of these terms. This is important because the physiology of each condition are quite different.
Laminitis = inflammation / pathology of the lamina.
Founder = Separation of the coffin bone from the hoof wall (detachment of the lamina).
Laminitis alone does not create an external physical change to the appearance of the hoof. Laminitis is inflammation within the lamina of the hoof capsule. It is extremely painful for the horse, and can cause heat in the hoof and a throbbing digital pulse, but it doesn't not create flare externally on the hoof capsule. Laminitis and founder are not mutually exclusive; a horse can have laminitis and not founder, and a horse can be "mechanically foundered" and not have laminitis. A horse can also have laminitis that subsequently leads to founder, but this can often be prevented. For more on this check out our new online course linked below.
Founder is a disconnection between the hoof wall and the coffin bone that leads to the formation of a lamellar wedge (stretched white line). It is a breakdown of the lamellar attachment that allows the hoof wall to migrate out and away from the coffin bone. This results in the coffin bone's tip rotating downwards towards the sole and produces the flare that you see visually on the outside of the hoof.
When looking at the growth rings of the hoof or at the wall structure itself it is important to know that in a healthy hoof the growth from the coronary band to the ground should be at a uniform angle as seen in the top hoof on the graphic below.
The hoof on the bottom of the graphic shows the wall coming in at a steeper angle at the top of the hoof and then progressively flaring as it grows down. The flaring indicates hoof wall disconnection and possibly founder. This graphic is from our newly released Laminitis and Founder Online Course. Check it out for more info on the complete rehab process and further clarification between laminitis and founder.
In the picture below you can see significant growth rings present both halfway down the hoof and also just below the coronary band. This was a picture sent to me by a student who was worried her horse had suffered laminitis and she had not noticed it. The horse had not been lame or sore but because of the growth rings she was worried that she wasn't on the right track with her trimming. I get asked this question a lot so I though it best to explore it in this post.
This horse was foundered when the student started trimming it a few months ago. I can tell this by the flared and rasped lamellar wedge in the bottom third of the hoof in comparison to the new growth angle at the top. With proper trimming resulting in a reduction of leverage on the lamellar wedge, the hoof wall and coffin bone that were once separated are reattaching. As they do so they are creating a tighter connection that when it grows down from the coronary band appears as a tighter growth ring. The first significant change is shown at the ring halfway down the hoof wall. This is when the correct trimming started that allowed the hoof wall connection to resume. The second ring just below the coronary band shows where the connection became even tighter as more of the wedge has been grown out.
The growth ring on the hoof below is not as significant as the picture above, but it is indicative of a tighter hoof wall connection as well. In this horse's case, it was a new living environment and diet that allowed more frequent correct trimming that caused it. While his hoof health was already good, the connection was able to improve creating the growth ring you can see just above the halfway point of his hoof wall.
Some people call these rings "event lines", and this is probably a more aptly named term, as they apply to an event that changed the connection of the hoof wall for some reason. These events can be more effective trimming methods, diet or living environment changes, health changes in the horse that affect hoof wall connection and more.
My goal with this post was to answer the question of: "Are these growth rings indications of a laminitis event?" This is a question I get asked often, and hopefully with just the little bit of hoof knowledge I shared in this post it should help to clear things up. If you are looking to further your knowledge of the hoof check out our Online Hoof Anatomy, Theory and Barefoot Trimming Course. This course provides an in depth study of hoof anatomy and function and is a beginners guide to learning how to trim their own horse.
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Kristi Luehr is a barefoot trimmer/farrier, author, and founder of the Okanagan School of Natural Hoof Care. She is certified by the Canadian Farrier School as well as the Oregon School of Natural Hoof Care, and also has certification in equine massage and dentistry. Her focus is to educate owners about hoof anatomy, function and proper barefoot trimming that supports and grows healthy and functional hooves specific to each horse's individual needs. She is the author of two online courses specific to hoof care and is always striving to create more educational content for students to learn from.