TH Equine Wellness

https://www.facebook.com/share/1RaMkyDcZv/?mibextid=wwXIfr

What is happening in a horse’s brain when they experience separation anxiety? Knowing the science can help us formulate a plan to help them through this common issue.

When a horse experiences the stress of separation, the brain shifts from a state of social connection to one of high-alert survival. This process is deeply rooted in the equine amygdala, which acts as the brain's alarm system. For a horse that has undergone past trauma, this part of the brain becomes hyper-reactive. Instead of processing a friend walking away as a temporary event, the amygdala floods the body with stress hormones like cortisol and adrenaline.

This neurobiological reaction is often linked to the panic and grief system located in the subcortical regions of the brain. When horses are separated from their herd or a specific bonded partner, they don't just feel lonely; they experience a form of emotional pain that is physically taxing. The frantic pacing, whinnying, and sweating often seen in these cases are outward manifestations of a brain that is literally screaming for social safety. Because horses are prey animals, being alone is historically synonymous with being vulnerable to predators, making the drive to reunite an biological imperative.

Trauma further complicates this by impacting the hippocampus, which is responsible for memory and context. In a healthy horse, the hippocampus helps the animal remember that they were alone for ten minutes yesterday and remained safe. However, chronic stress and high levels of cortisol can impair hippocampal function. This means a traumatized horse may lose the ability to put the current separation into a safe context, causing them to react to every departure with the same intensity as the original traumatic event.

Another significant factor is the concept of allostatic load, which refers to the cumulative wear and tear on the body and brain due to chronic stress. A horse with unresolved separation trauma lives in a state of constant vigilance. Their nervous system is often stuck in a sympathetic state, also known as fight-or-flight. Over time, this makes it harder for the horse to return to a calm, parasympathetic state. This internal physiological exhaustion can lead to more extreme behavioral outbursts because the horse has very little emotional or physical resilience left to handle minor changes.

This is why the "scream it out" method with the intention of helping horses to learn coping skills about separation anxiety almost always backfires. And this proves to be another reason why we always want to look at the science behind why our horses do the things they do.

The horse may also experience a sense of hyper-attachment as a survival strategy. Once they find a companion that makes them feel safe, they may cling to that individual with an intensity that seems irrational to us. This is because that companion has become the horse's external regulator for their nervous system. Without that presence, the horse's internal systems dysregulate, leading to the high-energy, reactive behaviors that characterize severe separation anxiety.

Addressing this issue requires a focus on rewiring these neural pathways rather than simply managing the behavior. READ THAT AGAIN. By using methods that prioritize the horse's emotional comfort and choice, it is possible to teach the brain that separation does not equal danger. This involves very slowly building the horse's confidence in short increments, allowing the prefrontal cortex to remain engaged so the horse can actually learn and process new, safe experiences. Over time, this structured approach helps your horse move out of a survival mindset and into a state of relaxed engagement.

When thoughtfully done, we as humans also become a source of comfort due to the classical conditioning we have established through positive reinforcement training alongside them.

A multi purpose leash, 6’ long. Can be used as a short leash, regular length or double.

A few new items made for a client.

https://www.facebook.com/share/p/1GJUVzczkc/?mibextid=wwXIfr

𝐀𝐫𝐞 𝐖𝐞 𝐒𝐭𝐚𝐫𝐭𝐢𝐧𝐠 𝐇𝐨𝐫𝐬𝐞𝐬 𝐓𝐨𝐨 𝐘𝐨𝐮𝐧𝐠? 𝐖𝐡𝐚𝐭 𝐭𝐡𝐞 𝐒𝐜𝐢𝐞𝐧𝐜𝐞 𝐀𝐜𝐭𝐮𝐚𝐥𝐥𝐲 𝐒𝐚𝐲𝐬 🏇 🦴

If you’ve followed my page for any length of time, you know I don’t sidestep controversy. Whether it’s blanketing, NSC in grass, or even salt (yes, that one surprised me too), the most debated topics are often the most worth examining. Because where uncertainty exists, I prefer to replace opinion with evidence. And there is nothing I love more than digging into peer-reviewed research to determine if what’s commonly accepted truly holds up to scientific scrutiny.

And few topics ignite more debate in the horse world than the question of when a young horse should begin work.

On one side, there’s concern that starting too early risks long-term soundness issues.

On the other, some argue that thoughtful early training may actually support bone development.

So instead of arguing from a point of instinct or tradition, I think it’s time to take a look at what the research actually says.

𝐆𝐫𝐨𝐰𝐭𝐡 𝐏𝐥𝐚𝐭𝐞 𝐂𝐥𝐨𝐬𝐮𝐫𝐞 𝐢𝐧 𝐇𝐨𝐫𝐬𝐞𝐬

Let’s begin by addressing the color-coded diagram of an equine skeleton that frequently circulates social media. This diagram illustrates when growth plates close, which begins in the lowest parts of each limb and moves up the skeleton sequentially, ending at the spine. This diagram is popular as many use it to justify recommendations on when to start horses.

I decided to do some digging to track down the origin of this information, and my investigation led me to a table in a book that was published in 1975. This table cites literature that evaluated the closure of the epiphyseal growth plate in the appendicular skeleton (forelimbs and hindlimbs) through radiographs (Getty, 1975).

Since then, a review by Rogers et al. (2021) was published and concluded that the majority of growth for horses is completed by the time they are 2 years old. Additional research evaluating the vertebrae suggest that longitudinal growth of the spine ceases when wither height growth is complete (Butler et al., 1993). Based on these findings, the reviewers suggested that starting horses at the age of 2 is an acceptable practice that aligns with their developmental potential.

But that begs the question whether we should base recommendations on growth plate activity and active bone growth or on growth plate fusion and closure – as these are two very different metrics. This was detailed in a presentation by Collar et al. (2020) in which growth plate activity of lumbosacral vertebrae in Quarter Horses stopped when horses were 2 years old but growth plate closure or fusion was not complete until horses were between 2 and 8 years old.

𝐒𝐨 𝐰𝐡𝐢𝐜𝐡 𝐦𝐞𝐚𝐬𝐮𝐫𝐞𝐦𝐞𝐧𝐭𝐬 𝐬𝐡𝐨𝐮𝐥𝐝 𝐰𝐞 𝐮𝐬𝐞 𝐚𝐧𝐝 𝐰𝐡𝐚𝐭 𝐝𝐨𝐞𝐬 𝐭𝐡𝐞 𝐫𝐞𝐬𝐞𝐚𝐫𝐜𝐡 𝐬𝐚𝐲?

When evaluating race horses, Santschi et al. (2017) found that horses who began training at 2 years of age did not have a higher risk of injury during their racing careers. In fact, they tended to have more successful careers including more lifetime starts, wins, earnings, and years raced.

At first glance, it may seem counterintuitive. But young, growing bodies are built to adapt and specifically, bone development is supported by high cellular activity, an active periosteum, abundant blood supply, and open growth plates. As the body matures, it gradually shifts from a state of building to maintaining. Hormonal changes occur, bones become less adaptable, and osteoblasts (bone-building cells) struggle to keep pace with osteoclasts (cells that break bone down).

In other words - the window for skeletal adaptation is early and we accept this reality in humans all the time.

Young athletes routinely begin training long before their growth plates close. Elite gymnasts, swimmers, and figure skaters often compete internationally as teenagers. Many children enter organized sports as early as five or six years old despite the fact that human growth plates typically remain open until they are 14 to 17.

𝐒𝐨 𝐰𝐡𝐲 𝐝𝐨𝐞𝐬 𝐞𝐚𝐫𝐥𝐲 𝐰𝐨𝐫𝐤 𝐢𝐧 𝐡𝐨𝐫𝐬𝐞𝐬 𝐩𝐫𝐨𝐯𝐨𝐤𝐞 𝐬𝐮𝐜𝐡 𝐬𝐭𝐫𝐨𝐧𝐠 𝐫𝐞𝐬𝐢𝐬𝐭𝐚𝐧𝐜𝐞 𝐰𝐡𝐞𝐧 𝐢𝐭 𝐢𝐬 𝐚𝐜𝐜𝐞𝐩𝐭𝐚𝐛𝐥𝐞 𝐟𝐨𝐫 𝐡𝐮𝐦𝐚𝐧𝐬?

I believe the controversy is not tied to the work itself, but rather the conditions surrounding the work.

Youth athletes are typically offered diversity in the exercise they are allowed to complete, do not have to carry an external load, and can refuse participation or voice concerns. Youth sports are also framed as a crucial part of both physical development and confidence building.

In comparison, young horses are often subjected to repetitive, discipline-specific movement, asked to carry a rider, tend to be confined outside of training, and have no autonomy regarding their participation. Equine sports, specifically those centered around young horses, tend to be tied to economic benefits, tradition, and human timelines that do not always put the horse first.

I believe this is where we have significant room for improvement in the equine industry.

Another consideration is the amount of research we have to provide recommendations. There are a wide variety of breeds and disciplines in the equine industry and the current data is not representative of all demographics. Additionally, for many, performance outcomes aren’t the whole picture. And at the moment, equine research does not extend past a horse’s athletic career, so we may not currently grasp long-term implications of early work.

𝐁𝐮𝐭 𝐭𝐡𝐢𝐬 𝐢𝐬 𝐰𝐡𝐞𝐫𝐞 𝐰𝐞 𝐜𝐚𝐧 𝐮𝐬𝐞 𝐡𝐮𝐦𝐚𝐧 𝐫𝐞𝐬𝐞𝐚𝐫𝐜𝐡 𝐭𝐨 𝐨𝐟𝐟𝐞𝐫 𝐮𝐬 𝐚 𝐮𝐬𝐞𝐟𝐮𝐥 𝐩𝐞𝐫𝐬𝐩𝐞𝐜𝐭𝐢𝐯𝐞.

One of the clearest risks in youth athletics isn’t early movement, it’s repetition without variation.

While sports offer health benefits, single-sport specialization in children has been strongly linked to higher injury rates (Jayanthi et al., 2019). These risks are associated with children performing the same movements repetitively, which puts stress on the same joints and strains the same muscles.

Overuse injuries are especially likely during rapid growth phases, when muscle imbalances and coordination shifts are common (Arnold et al., 2017). This is because active growth is often tied to bone growth that outpaces muscles and tendon development. This imbalance can result in tight muscles, reduced flexibility, and structural instability, which temporarily declines coordination and balance and increases the risk of injury.

Youth athletes also face an increased risk of early-onset osteoarthritis which is linked to high-impact activities, repetitive movements, and severe joint injuries, all of which can accelerate cartilage degeneration (Saxon et al., 1999). However, osteoarthritis wasn’t identified until later in life due to a higher pain tolerance in youth and the time it takes for the condition to develop. I believe a long-term study evaluating this relationship in horses would be extremely insightful.

𝐒𝐨 𝐭𝐡𝐞 𝐢𝐬𝐬𝐮𝐞 𝐢𝐬𝐧’𝐭 𝐬𝐢𝐦𝐩𝐥𝐲 𝐰𝐡𝐞𝐭𝐡𝐞𝐫 𝐲𝐨𝐮𝐧𝐠 𝐛𝐨𝐝𝐢𝐞𝐬 𝐬𝐡𝐨𝐮𝐥𝐝 𝐰𝐨𝐫𝐤 𝐛𝐮𝐭 𝐡𝐨𝐰 𝐭𝐡𝐞𝐲 𝐰𝐨𝐫𝐤.

The key takeaway is that early training is not inherently harmful, rather the structure and approach to that training are what make the difference.

Variety is critical. Cross-training helps distribute stress across tissues and reduces the risk created by repetitive movement patterns. Youth athletes who were highly specialized in a single sport were almost twice as likely to sustain an overuse injury compared to someone competing in multiple sports (Bell et al., 2018). Trail rides, cavaletti work, or practicing a new discipline are all opportunities to not only improve musculoskeletal health but also support a horse’s mental wellbeing.

Short, intentional bouts of higher-intensity loading may stimulate bone adaptation more effectively than long periods of low-intensity exercise – as bone requires a dynamic strain above threshold to elicit bone formation. This was demonstrated by a study evaluating endurance horses completing ‘long, slow’ work, which found that horses in endurance training did not increase bone strength compared to horses allowed to freely exercise on pasture (Spooner et al., 2008).

Meanwhile, sprint exercises have been shown to result in greater bone strength (Logan et al., 2019), increased endosteal circumference (Firth et al., 2012), and greater bone mineral content (Hiney et al., 2004). However, balance is critical. When young horses were sprinted excessively, it had harmful impacts on joint health as the horse was responding to an unnatural amount of work (Van de Lest et al., 2002). While we still need to determine the appropriate level of high-impact work for horses, one study found that just one sprint a week could increase bone strength (Logan et al., 2019).

Load matters, too, and some weight-bearing can be beneficial. Research found that horses carrying 100 lbs while trotting had greater bone mineral deposition of the cannon bone compared to those who did not carry weight (Nielsen et al., 2002). However, it is important to note that the load these horses carried does not reflect most riding situations. In comparison, excessive loads could be detrimental to the horse and rider size is a real consideration when starting young horses.

Movement also builds coordination, balance, and proprioception. Expecting a horse to enter athletic work at maturity without foundational motor skills would be like asking a 22-year-old to learn and compete in a sport like soccer or gymnastics against someone who has trained since childhood. Early exposure to low-intensity technical challenges such as balance, body awareness, and varied terrain, can be incredibly valuable.

𝐀𝐧𝐝 𝐩𝐞𝐫𝐡𝐚𝐩𝐬 𝐦𝐨𝐬𝐭 𝐢𝐦𝐩𝐨𝐫𝐭𝐚𝐧𝐭𝐥𝐲: 𝐥𝐢𝐟𝐞𝐬𝐭𝐲𝐥𝐞 𝐦𝐚𝐭𝐭𝐞𝐫𝐬.

Work is only a small part of a horse’s day.

A two-year-old that is lightly trained but lives in turnout and is allowed to move freely, navigate space, and engage in natural behaviors, is experiencing something very different from one that lives in a stall for the majority of the day.

This is backed by research in which young horses pastured for at least 12 hours a day had greater bone mineralization and cannon bone circumference in comparison to their counterparts who lived in a stall (Bell et al., 2001). Since young horses often live in stalls during sale prep or once they enter training, they may be more likely to have bone loss or an increased risk of injuries. While that stall may be convenient for us, movement outside of structured exercise is critical for musculoskeletal development as well as mental wellbeing.

𝐀𝐫𝐞 𝐰𝐞 𝐚𝐬𝐤𝐢𝐧𝐠 𝐭𝐡𝐞 𝐫𝐢𝐠𝐡𝐭 𝐪𝐮𝐞𝐬𝐭𝐢𝐨𝐧?

Perhaps the real issue isn’t if young horses should work or even what age to start them, but whether the work we ask of them is age-appropriate.

Most horses are still in an active growth phase until around 2 years of age, and during this time, structured work should be limited while free movement through pasture turnout may be the most appropriate and beneficial form of loading.

Once rapid growth begins to slow, workload can be introduced thoughtfully and tailored to the individual, taking into account breed, maturity, and current developmental stage. At this point, how we develop the horse matters far more than simply when we begin.

𝐂𝐨𝐧𝐜𝐥𝐮𝐬𝐢𝐨𝐧

If I had to summarize some recommendations, they would include:

🌱 House your horse in a pasture or paddock over a stall.

🏋️ Cross train to reduce the risk of overuse injuries.

⚖️ Focus on low intensity, technical work at a young age to improve coordination and proprioception.

🏇 Utilize high-intensity work strategically to increase bone strength.

📈 Minimize work during any growth spurts.

🐴 Make decisions for your specific horse based on individual growth and characteristics.

The bottom line is that early work itself isn’t the issue - what really matters is how young horses are trained, managed, and allowed to live.

If you want to read more on this topic, I encourage you to read an open access review (which means it is accessible to everyone!) by Logan and Nielsen (2021) which highlighted a lot of the research I covered in this post. I will include a link in the comments!

There’s always more to unpack, but hopefully this reframes the conversation in a way that allows us to use science to mold our decisions instead of tradition.

Cheers,
Dr. DeBoer

Table 15-2; Getty R(ed): Sisson and Grossman's The Anatomy of the Domestic Animals , ed 5. Philadelphia , WB Saunders Co , 1975, p 272.

Rogers CW, Gee EK, Dittmer KE. Growth and bone development in the horse: when is a horse skeletally mature?. Animals. 2021 Nov 29;11(12):3402.

Butler, J.A., Colles, C.M., Dyson, S., Kold, S., Poulos, P. Clinical Radiology of the Horse. 1993.

Collar, E. M., Russell, D. S., Huber, M. J., Duesterdieck-Zellmer, K. F., & Stover, S. M. (2020). Investigation into lumbosacral vertebral anatomy and growth plate closure in Quarter Horses [Video]. AAEP Proceedings. American Association of Equine Practitioners.

Santschi, E.M.; White, B.J.; Peterson, E.S.; Gotchey, M.H.; Morgan, J.M.; Leibsle, S.R. Forelimb Conformation, Sales Results, and Lifetime Racing Performance of 2-Year-Old Thoroughbred Racing Prospects Sold at Auction. J. Equine Vet. Sci. 2017, 53, 74–80.

Jayanthi NA, Post EG, Laury TC, Fabricant PD. Health consequences of youth sport specialization. Journal of athletic training. 2019 Oct 1;54(10):1040-9.

Arnold A, Thigpen CA, Beattie PF, Kissenberth MJ, Shanley E. Overuse physeal injuries in youth athletes: risk factors, prevention, and treatment strategies. Sports health. 2017 Mar;9(2):139-47.

Saxon L, Finch C, Bass S. Sports participation, sports injuries and osteoarthritis: implications for prevention. Sports medicine. 1999 Aug;28(2):123-35.

Bell DR, Post EG, Biese K, Bay C, Valovich McLeod T. Sport specialization and risk of overuse injuries: a systematic review with meta-analysis. Pediatrics. 2018 Sep 1;142(3):e20180657.

Spooner HS, Nielsen BD, Woodward AD, Rosenstein DS, Harris PA. Endurance training has little impact on mineral content of the third metacarpus in two-year-old Arabian horses. Journal of Equine Veterinary Science. 2008 Jun 1;28(6):359-62.

Logan, A., Nielsen, B., Robison, C., Manfredi, J., Schott, H.; Buskirk, D., Hiney, K. Calves, as a model for juvenile horses, need only one sprint per week to experience increased bone strength. J. Anim. Sci. 2019, 97, 3300–3312.

Firth, E.C., Rogers, C.W., Rene van Weeren, P., Barneveld, A., Wayne McIlwraith, C., Kawcak, C.E., Goodship, A.E., Smith, R.K.W. The Effect of Previous Conditioning Exercise on Diaphyseal and Metaphyseal Bone to Imposition and Withdrawal of Training in Young Thoroughbred Horses. Vet. J. 2012, 192, 34–40.

Hiney, K.M., Nielsen, B.D., Rosenstein, D. Short-Duration Exercise and Confinement Alters Bone Mineral Content and Shape in Weanling Horses. J. Anim. Sci. 2004, 82, 2313–2320.

Van de Lest, C., Brama, P.A.J., René Van Weeren, P. The Influence of Exercise on the Composition of Developing Equine Joints. Biorheology 2002, 39, 183–191.

Bell RA, Nielsen BD, Waite K, Rosenstein D, Orth M. Daily access to pasture turnout prevents loss of mineral in the third metacarpus of Arabian weanlings. Journal of animal science. 2001 May 1;79(5):1142-50.

Nielsen BD, O'Connor CI, Rosenstein DS, Schott HC, Clayton HM. Influence of trotting and supplemental weight on metacarpal bone development. Equine Veterinary Journal. 2002 Sep;34(S34):236-40.

https://drkhorsesense.wordpress.com/2025/02/01/__trashed-2/

Cold-Induced Hoof Pain, aka Winter Laminitis It’s been a few years since I ran this blog but people are continually having to deal with it for the first time, and this year has been particularly brutal. Frozen and lumpy ground can make …

https://www.facebook.com/share/p/1AsgSU9EuK/

💧 𝐃𝐨 𝐌𝐚𝐬𝐡𝐞𝐬 𝐀𝐜𝐭𝐮𝐚𝐥𝐥𝐲 𝐈𝐧𝐜𝐫𝐞𝐚𝐬𝐞 𝐖𝐚𝐭𝐞𝐫 𝐈𝐧𝐭𝐚𝐤𝐞 𝐢𝐧 𝐇𝐨𝐫𝐬𝐞𝐬?

Soaking feed or utilizing mashes is a common practice intended to increase water intake in horses - but does it actually help?

I decided to take a dive into the research, as many horse owners soak feed in the winter, particularly during cold weather snaps, to encourage water intake. And while digging, I came across two studies you may find interesting!

🧪𝐒𝐭𝐮𝐝𝐲 𝟏 (𝐅𝐞𝐫𝐫𝐞𝐢𝐫𝐚 𝐞𝐭 𝐚𝐥., 𝟐𝟎𝟐𝟓)
The first study took place in Florida, where the average ambient temperature during the study was 55°F (13°C). This research evaluated horses consuming soaked pelleted feed, alfalfa cubes, or beet pulp in a 2:1 ratio of water to concentrate.

This study found that horses rapidly self-regulated voluntary water intake based on the amount of water provided in the meal. This means, when water was added to their feed, they voluntarily drank less so total water consumption remained the same.

This was shown as horses on dry feed had a voluntary water intake of 32.2 L while horses on soaked feed reduced voluntary water intake to 25.4 L to accommodate the ~6 L of water provided in the mash, for a total water intake of 31.5 L.

But that brings us to the second study 👇

❄️ 𝐒𝐭𝐮𝐝𝐲 𝟐 (𝐑𝐮𝐜𝐤𝐞𝐫 𝐚𝐧𝐝 𝐇𝐢𝐧𝐞𝐲, 𝟐𝟎𝟏𝟑)
This study evaluated seasonal differences in water intake during the fall (55°F; 12.8 °C) and winter (-4 to 33°F; -20 to 0.67°C) in Wisconsin. Horses were fed a pelleted concentrate at 0.5% body weight, with soaked feed provided at 2 L water/kg feed.

This study found that horses drank:
🍁 29.3 L/day in the fall
❄️ 24.7 L/day in the winter

This decrease supports previous findings that water intake drops by approximately 6–12% during the cold winter months.

However, this study also evaluated soaked vs dry feed.

While no difference in voluntary water intake was observed during the fall trial, horses in the winter consumed more water when eating a mash (26.9 L) compared to when consuming dry feed (22.4 L), a difference of about 1.2 gallons per day. The study found that horses consuming the mash drank equal to or more water than horses consuming the dry grain, in addition to the water they consumed in their feed.

✨𝐓𝐚𝐤𝐞-𝐡𝐨𝐦𝐞 𝐦𝐞𝐬𝐬𝐚𝐠𝐞
Cold weather can reduce voluntary water intake in horses, but feeding a mash during winter can help combat that decline. In more mild weather, however, soaking feeds likely does not increase total water intake, as horses will self-regulate.

Will these studies make you more likely to soak you feeds - why or why not?

Stay warm out there!
Dr. DeBoer

Ferreira N, Binder D, Garbati IH, Lance JM, Warren LK. Effect of soaking feed on water intake and hydration in horses. Journal of Equine Veterinary Science. 2025 May 1;148:105449.

Rucker NK, Hiney KM. Voluntary water intake in horses when fed a dry versus mash grain in two different seasons. Journal of Equine Veterinary Science. 2013 May;33(5):355-6.

https://www.facebook.com/share/p/1Bt8WcRcuZ/?mibextid=wwXIfr

❄️ 𝐖𝐢𝐧𝐭𝐞𝐫 𝐅𝐞𝐞𝐝𝐢𝐧𝐠: 𝐖𝐡𝐲 𝐇𝐚𝐲 𝐌𝐚𝐭𝐭𝐞𝐫𝐬 ❄️

🔥 𝐇𝐚𝐲 = 𝐈𝐧𝐭𝐞𝐫𝐧𝐚𝐥 𝐇𝐞𝐚𝐭
The best way to warm up your horse in the winter is to provide hay!

Hay is primarily digested in the hindgut through a process known as fermentation, which generates a significant amount of metabolic heat. This means hay acts as a fuel of sorts for the horse’s very own internal furnace, helping warm them from the inside out.

⚡ 𝐂𝐨𝐥𝐝 𝐰𝐞𝐚𝐭𝐡𝐞𝐫 𝐢𝐧𝐜𝐫𝐞𝐚𝐬𝐞𝐬 𝐞𝐧𝐞𝐫𝐠𝐲 𝐝𝐞𝐦𝐚𝐧𝐝𝐬
Not only that, but when the weather is cold, a horse has increased caloric demands, as they require extra energy to maintain body temperature. This means providing extra hay during a cold snap not only helps generate internal heat, but also helps meet the additional calorie requirements associated with cold weather.

🌾 𝐖𝐡𝐞𝐧 𝐡𝐚𝐲 𝐢𝐬 𝐟𝐞𝐝 𝐢𝐧 𝐬𝐞𝐭 𝐚𝐦𝐨𝐮𝐧𝐭𝐬
While I provide unlimited access to forage year-round, I have been to many barns that provide set amounts of hay at mealtime. This can become problematic when temperatures fall below the horse’s lower critical temperature (LCT).

🌡️ 𝐖𝐡𝐚𝐭 𝐢𝐬 𝐭𝐡𝐞 𝐋𝐨𝐰𝐞𝐫 𝐂𝐫𝐢𝐭𝐢𝐜𝐚𝐥 𝐓𝐞𝐦𝐩𝐞𝐫𝐚𝐭𝐮𝐫𝐞 (𝐋𝐂𝐓)?
The LCT represents the temperature at which a horse begins to expend additional energy to stay warm. The farther below the LCT the temperature falls, the more energy the horse must use to maintain body temperature.

The LCT can vary based on the individual horse, acclimation to the current climate, hair coat, and weather conditions.

Specifically:

❄️ A horse acclimated to a cold climate with a long winter coat has an LCT of 18°F

🌤️ A horse acclimated to a warm climate with a short coat has an LCT of 41°F

🌧️ A wet hair coat is especially important, as it can increase the LCT to 59°F

📈 𝐖𝐡𝐲 𝐝𝐨𝐞𝐬 𝐭𝐡𝐞 𝐋𝐂𝐓 𝐦𝐚𝐭𝐭𝐞𝐫?
This value is important because for every degree below the LCT, a horse’s energy requirements increase by approximately 1%.

For example, if you have a horse acclimated to a cold climate and the outside temperature is 0°F, their energy requirements increase by 18%.

🧮𝐃𝐞𝐭𝐞𝐫𝐦𝐢𝐧𝐢𝐧𝐠 𝐡𝐨𝐰 𝐦𝐮𝐜𝐡 𝐞𝐱𝐭𝐫𝐚 𝐡𝐚𝐲 𝐭𝐨 𝐟𝐞𝐞𝐝
To determine how much additional hay is required, you must first estimate the horse’s baseline energy requirements. I personally use the NRC Requirements of the Horse – Working Doc, where I input body weight and current life stage to estimate maintenance energy needs.

Once this value is determined, I use the digestible energy (calories) reported on my hay test to calculate how many additional pounds of hay are needed to meet the increased energy demand.

🌿 𝐏𝐮𝐭𝐭𝐢𝐧𝐠 𝐢𝐭 𝐢𝐧𝐭𝐨 𝐩𝐫𝐚𝐜𝐭𝐢𝐜𝐞
As you can see from this example, providing nearly 10 additional pounds of hay per horse may not always be feasible. This is why I keep a high-quality alfalfa hay on hand, which allows me to help meet increased caloric demands in a quantity the horse can realistically consume.

I think it is also important to remember that blanketing or housing horses in insulated or heated barns may alter these recommendations, as the body does not need to work as hard to stay warm. This equation helps provide an estimate but we can expect some variability!

✅ 𝐂𝐨𝐧𝐜𝐥𝐮𝐬𝐢𝐨𝐧
On these cold days, make sure the first thing you reach for to help your horse stay warm is some extra hay! Not only does it fuel their internal furnace, but it also provides additional calories they require to maintain their core body temperature. This equation can help estimate how much extra hay may be needed during cold weather!

Stay warm out there ❄️🐴
Dr. DeBoer

https://www.facebook.com/share/17oQLFzQGk/?mibextid=wwXIfr

❄️ 𝐏𝐢𝐥𝐨𝐞𝐫𝐞𝐜𝐭𝐢𝐨𝐧: 𝐓𝐡𝐞 𝐇𝐨𝐫𝐬𝐞’𝐬 𝐁𝐮𝐢𝐥𝐭-𝐈𝐧 𝐖𝐢𝐧𝐭𝐞𝐫 𝐁𝐥𝐚𝐧𝐤𝐞𝐭 🐴

Time to bring back one of the very first topics I discussed on this page: piloerection. I write a lot about blanketing because it can be a great management tool when done well. But it’s also important to highlight how a horse naturally thermoregulates without human intervention!

When a mammal becomes cold, the goal is simple: conserve heat as efficiently as possible. This process begins with cold-sensitive thermoreceptors in the skin, which activate the sympathetic nervous system. That activation triggers the pilomotor reflex, similar to goosebumps in humans.

During this reflex, sympathetic nerves stimulate the arrector pili muscles to contract. These small smooth muscles attach the skin to the base of each hair follicle, and when they contract, the hair stands on end. This process, known as piloerection, allows air to be trapped between the hairs, creating an insulating layer that helps reduce heat loss.

I like to use a scuba diving analogy here. A wetsuit doesn’t keep you dry, instead, it traps a thin layer of water against your skin. Once that layer warms up, you’re no longer losing heat to fresh, cold water every second. Without it, your body would be trying (and failing) to warm an entire ocean.

Piloerection works the same way. By trapping a layer of air between the erect hairs, the horse’s skin isn’t constantly exposed to new cold air, which helps conserve body heat.

🌬️𝐖𝐡𝐞𝐫𝐞 𝐭𝐡𝐢𝐬 𝐬𝐲𝐬𝐭𝐞𝐦 𝐢𝐬 𝐜𝐨𝐦𝐩𝐫𝐨𝐦𝐢𝐬𝐞𝐝

Piloerection is effective, but it’s not foolproof. Wind and rain can significantly disrupt this process. Wind strips away the trapped air layer, and rain flattens the hair coat, preventing the hairs from standing up at all. This is likely why studies consistently show that horses seek shelter or prefer blankets during windy and wet conditions.

A wet hair coat is especially problematic. When the coat becomes saturated, the insulating air layer is lost, and water conducts heat away from the body far more efficiently than air. At that point, piloerection can’t function as intended, and heat loss increases rapidly.

🧣𝐁𝐥𝐚𝐧𝐤𝐞𝐭𝐢𝐧𝐠, 𝐩𝐢𝐥𝐨𝐞𝐫𝐞𝐜𝐭𝐢𝐨𝐧, 𝐚𝐧𝐝 𝐦𝐨𝐢𝐬𝐭𝐮𝐫𝐞

Blanketing can absolutely support horses in challenging conditions, but it’s important to recognize that when a horse is blanketed, piloerection no longer occurs. Whether that’s because the horse is already warm enough or because the weight of the blanket physically interferes with hair elevation isn’t fully understood.

This has raised concerns about the use of uninsulated sheets in winter. While we don’t have a definitive answer yet, a pilot study I conducted two winters ago suggests moisture management may be the key issue. Sheets lack insulating fill that can absorb or buffer moisture generated beneath the blanket. As a result, damp air can become trapped against the coat and skin - and cold plus moisture is not a good combination.

In contrast, blankets with added fill can absorb some of this moisture, helping maintain a warmer, drier microclimate next to the horse’s body.

🧠𝐒𝐨 𝐰𝐡𝐚𝐭 𝐝𝐨𝐞𝐬 𝐭𝐡𝐢𝐬 𝐦𝐞𝐚𝐧 𝐢𝐧 𝐩𝐫𝐚𝐜𝐭𝐢𝐜𝐞?

This doesn’t mean you shouldn’t blanket. It means that if you choose to blanket, the insulation provided must be equal to or greater than what the horse would achieve through piloerection alone. If that threshold isn’t met, we may actually be reducing thermal protection rather than improving it.

The challenge, of course, is that there’s no one-size-fits-all answer. Weather conditions, wind, precipitation, individual horse characteristics, hair coat, metabolic rate, and blanket weight all interact. That complexity is exactly why blanketing should be viewed as an active management decision, not a set-and-forget solution.

Next time you’re at the barn on a cold day, take a moment to watch an unblanketed horse and notice the subtle ways they work to stay warm. It’s a remarkable, and often overlooked, physiological process.

And if any blanketing companies out there want to collaborate on future research - you know where to find me!

Cheers,
Dr. DeBoer