Are Hoof rings a sign of inflammation / laminitis?
The answer is NOT NECESSARILY but they are a clear sign management/forage changes are in order.
The hoof wall grows down from the coronet, so the quality of the new growth is determined by the horse’s diet. It is normal to have variations in the growth rate from winter to spring for example.
Benign hoof rings are horizontal and are a record of the changes to the metabolism of the horse and the nutrients delivered to the coronet over the last 10-12 months.
When the horse’s main forage consists of green vegetative grass, not only changes of the season but also of the weather cause fluctuations in the nutrient composition of the grass. In our opinion, because the hoof wall comprises 90% protein, changes in crude protein content are very likely a contributor to the formation of hoof rings.
Hoof rings can vary from barely noticeable lines to actual ‘ridges’ depending on the degree of disruption at the coronet. When they are minor they aren’t a concern but when they are ridges they should not be ignored and are signs the horses forage needs to be stabilised – ideally to higher fibre, more mature grass which is less prone to fluctuations.
They do not necessarily mean there is/has been inflammation: “a localized physical condition in which part of the body becomes reddened, swollen, hot, and often painful, especially as a reaction to injury or infection”.
If it was inflammation, the coronet band would show signs of it each time it happened and you would notice it!
When the horse’s metabolism has suffered sufficient insult to cause more serious metabolic/endocrine disorders, catastrophic damage to the circulation inside the hoof capsule occurs and you have laminitis. Once physical forces come into the equation distortion of the hoof capsule is the result – the difference in growth rate between the heel and the toe cause the hoof rings to diverge – become wider apart towards the heel. Then the hoof rings are advertising chronic laminitis as in the following picture.
The hoof rings the first picture were not accompanied by any signs of laminitis. The horse was sound and not in pain.
Sometimes hoof rings are referred to as ‘Event lines’ – one or two may be evident, and may be caused any time the horse has a high temperature, infection, inflammation or a sudden significant change in diet – anything that affects the circulation and therefore the nutrient delivery to the coronet band.
When the horse is fed properly and all his dietary requirements for fibre, protein (not nitrate protein from green pasture and legumes), minerals, vitamins are met, the hoof wall grows optimally and evenly – not in fits and starts...
To summarise, the nutrient composition of the grass affects the horse’s circulation, especially peripheral delivery of nutrients to the coronet band where growth is initiated and can cause anything from 'lines' to palpable 'ridges'.
When horses live on forage with a much more stable nutrient composition (as in mature grass, or hay) the hoof wall grows down flawlessly
A stretched white line is NOT necessarily a sign of laminitis. There are literally thousands of horses whose hooves are not trimmed regularly enough and who have stretched white lines but do not have laminitis. The horse in the following photos is just one example. Not great, but not laminitis.
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