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Advanced Topics In Horse Nutrition: Health Conditions

A horse eats hay in a slow feeder bag
Niblet has had a number of dietary adjustments made to help treat laminitis.

We previously covered the basics of horse nutrition in our Daily Diet, Treats, And Supplements For Horses resource. If you haven’t read it, we recommend taking a look at it before reading this resource as it creates a foundation for learning more about horse nutrition. This resource expands on the foundational resource, focusing on dietary factors that can come into play when considering diet changes for horse residents with certain health conditions. In our last resource we learned a bit about how a horse’s digestive system works and discussed the building blocks of the dietary needs of horses. Forage and concentrates, vitamins and minerals, and the appropriate ratios and percentages of each of these is also important! The types and amounts of these needed may change for many horses if they develop certain health conditions or those conditions progress or regress. It can be a lot to take in. Here we will break it down into different areas of dietary consideration.

If you recall from our basic nutrition resource, on average, a healthy adult horse will consume 1.5%-2.5% of their weight each day. Forage quality and type will affect the nutritional value a horse consumes. Based on those levels, a horse may require some supplementation of concentrates or vitamins and minerals. It is recommended that the forage growing in the pasture and the hay purchased be tested for nutritional value to allow you and your veterinarian and/or equine nutritionist to develop the best diet plans for resident horses. 

To maintain a healthy horse’s weight and nutritional intake, it is important to know:

  1. How much they weigh (approximately)
  2. How much a horse consumes each day (1.5%-2.5% of their body weight), and
  3. The nutritional value of the forage and food provided

One Size Doesn’t Fit All
This is not a “one size fits all” guideline. Every horse is an individual and requires individually designed diets, depending on a number of factors. However, different groups of horses tend to have different generalized needs based on those factors. This resource seeks to provide you information on some of the general considerations given to horse diets for residents with common health conditions. 

Health Factors Affecting Dietary Needs For Horses

If you are caring for horse residents with health conditions at your sanctuary, there are dietary changes that you might consider depending on the health of each individual. Horse residents with these conditions may require changes in the type and amount of food in their diet, in addition to how those foods are prepared. 

The listed conditions below require a diagnosis before diet changes should be considered. Many conditions have similar symptoms, and without a proper diagnosis, a change in food may cause more harm than good. Below are some generalized examples of how diet can be used to manage various diseases and illnesses. 

Consult A Veterinarian!
This is not meant to replace veterinary advice regarding individual diet plans for horse residents. Doing so could result in serious health complications for residents, as the details of each individual’s health are specific to them. Horse residents with certain conditions require specialized plans made with the assistance of experienced equine veterinarians and equine nutritionists. The information provided below and throughout this resource are meant to familiarize caregivers with general considerations for resident populations with health conditions, giving them a foundation on which to further seek guidance and discuss diet plans with their veterinarians and nutritionists. If you haven’t yet, please refer to our disclaimer.

Anemia

Anemia clinically presents as a reduction of oxygen transported to tissues, and there are fewer red blood cells in the bloodstream of the affected individual. There are many possible underlying causes for anemia, which range from obvious blood loss from an injury or surgery, to heavy parasite loads, nutritional deficiencies, ulcers, and even cancer. This range of severity of conditions makes it particularly important to consult your veterinarian. Depending on the diagnosis, anemia can be a chronic health issue. 

In cases where anemia is caused by nutritional deficiencies, some dietary supplementation can be beneficial. A deficiency in iron, protein, B vitamins, and/or copper could affect the ability of a resident’s body to manufacture enough red blood cells. Your veterinarian may advise the addition of oats or oat oil to their diet, as some research has indicated that it can be helpful in treating certain cases of anemia or other possible supplements to address the issue.

Colic

Colic is one of the health issues that you will likely come across if you care for horses. Afflicted horses may experience intense abdominal pain, loss of appetite, depression, constipation, and a swollen abdomen. They may roll around trying to relieve the pain, paw the ground, or kick or look at their side. They may also stretch their body out or curl their lip and arch their necks. Colic is serious and a veterinarian should be called immediately if it is suspected. Because the cause and severity of the colic can vary, diet guidelines will depend on the diagnosis. During an episode of colic, remove any food in their living space. Remove water as well until directed otherwise by your veterinarian. Depending on the complexity and severity of the colic, a veterinarian may recommend easing back into their normal diet and starting off with multiple smaller meals throughout the day. They may also suggest lowering or removing grain from their diet for a time. Other horses may have a simple case of colic that has resolved within a day and require less specialized dietary instructions.

Constipation

Constipation is an uncomfortable and sometimes serious condition. There are a number of factors that can lead to constipation, including poor dental health, ingestion of sand or foreign objects, or poor diet.To ensure a healthy intestinal tract, feed residents forage before any grain and provide constant access to water. If you have a resident who is prone to constipation, a veterinarian or equine nutritionist might recommend adding more fibrous components to their diet, such as beet pulp or bran. Because some causes are not diet related, it is important to consult your veterinarian about treatment options and whether the resident requires special veterinary care. 

Cushing’s Disease

Cushing’s Disease, also known as pituitary pars intermedia dysfunction (PPID), is a metabolic disease that is caused by a pituitary gland tumor. Horses with Cushing’s disease may urinate, sweat, drink excessively, have poor, thick coats, muscle loss, or have laminitis. A horse with cushing’s disease often struggles with being overweight or underweight. This factor affects their dietary requirements.

Horses with Cushing’s Disease will need food that has a low glycemic index as they are insensitive to insulin. Those with excess weight will require a highly forage-based diet. Those struggling to gain weight will need extra calories from fermentable fiber, such as beet pulp, and fat, such as vegetable oil. Beet pulp can also be soaked and drained to remove even more sugar even though it is usually already low in sugar. Soy hulls can also be used to avoid sugar while providing calories. Access to pasture should be carefully planned. If given access to pasture, they should be given access in the early morning to limit the amount of fructan they consume. To prevent over consumption, grazing muzzles can be used. Some horse residents may do better on a dry lot.

Supplements may need to be provided depending on the nutritional content of the forage provided. It is advisable to have the nutritional content of the forage analyzed. Because they need lower levels of sugar in their diet, it is best to provide late cut grass hay as it contains less sugar. Hay should have 10-12% max (less is better) in starch and sugars. If you are uncertain about the starch and sugar levels in the hay you have available, soaking the hay then draining off the water can reduce the amount of sugar they consume. Haylage may also be a possibility for some horses, but it shouldn’t be soaked as there is a risk of secondary fermentation. If you need to soak the hay to reduce the sugar/starch content, 30 minutes in hot water (or more time if soaking in cold water) is a good amount of time. However, soaking hay can also remove other nutrients that are important for the resident, so care must be taken to supplement these nutrients when necessary. Forage should be analyzed to allow you and your veterinarian to develop a precise diet plan, something that is vital for horses with Cushing’s Disease.

Once you have developed a plan with your veterinarian, you will need to ensure that both concentrates and hay are weighed and offered in the correct amounts. A digital scale can help ensure your resident is getting exactly what they need. If a resident has pasture access, a grazing muzzle (as mentioned above) can help ensure they don’t consume too much grass. Slow-feeder hay nets and other specially designed products can also slow their intake.

Dental Health 

One of the top factors that can come into play is poor dentition. As horses age, their teeth simply grow until they are gone, leaving some individuals without a way to properly chew their food. This can greatly affect digestion and can lead to impactions. There are a number of dental issues that can change the way their diet is consumed and may necessitate dietary changes. Teeth can fracture or have gaps, sharp points, or wear patterns that make it more difficult for a horse to effectively grab and grind their food. If a horse has trouble eating, they are likely to start losing weight to an unhealthy degree. In cases like these, identifying the nutritional needs and how those needs can be met through a change in diet is important. If poor dental health is affecting a resident’s nutritional intake, caregivers might try chopping and soaking quality hay for residents, as this is easier to chew. Complete foods, beet pulp, and bran can be soaked as well. Generally it is thought that loose-textured feeds like sweet feed are more challenging to chew.

Developmental Orthopedic Disease

This is a disease that affects growing horses and is likely due to an over-consumption of food followed by an individual growing too quickly. While there may be a genetic component for the disease, it primarily presents in foals with an improper diet consuming more energy-rich nutrients than they can use. Some mares produce an overabundance of milk, and if a foal nurses too much, it may lead to this disease. In other cases, it may arise when a foal eats large amounts of creep food and snacks on momma’s concentrates! Foals still need higher levels of protein in their diet, but they don’t need excess energy coming from their food sources. Offering growing horses high-quality grass and ensuring necessary minerals and vitamins are appropriately supplemented is a good way to regulate growth. Don’t feed growing residents a diet too high in alfalfa, as that could cause an imbalance between calcium and phosphorus levels and lead to other developmental musculoskeletal issues. In cases of a nursing foal exhibiting signs of DOD, it may be necessary to wean them a little earlier than you normally might, though this should be done with great attention given to the individual’s physical and psychological health! 

Diarrhea

At some point, a resident is bound to experience diarrhea. There are many possible causes, so it is important to do a full health check to look for signs of other symptoms that may be indicative of an underlying health condition. Some symptoms to check for include loss of appetite, depression, weight loss, colic, dull coat and/or eyes, “pot belly” appearance, increased thirst, or dehydration. Often cases of diarrhea are temporary, and a resident may recover so quickly you don’t have a chance to identify the cause. Sudden changes in diet, antibiotic or NSAID use, and stress can cause a bout of diarrhea that is generally easy to treat. Bacterial infections and intestinal parasites can also cause diarrhea, as can other, more serious conditions.

If you believe your resident just has a temporary case of an upset tummy, there are some diet management tips to help them recover. Be sure to speak with your veterinarian if the resident presents with other symptoms, or if the diarrhea doesn’t go away after a couple days. If a resident has diarrhea, limit their access to green grass and particularly rich foods. Water should be readily available and electrolytes provided as well. If the resident is being fed a diet high in alfalfa, you might consider decreasing the amount until they are well again. Grass hay should make up the majority of their diet.

Enteroliths

You may have heard enteroliths, which are also referred to as intestinal stones or calculi. They are masses of minerals that usually form around a foreign object (wood, twine, hair, or other objects) in the gut. Some horses are lucky enough to pass small enteroliths, but some enteroliths are too large to move through their system. Larger enteroliths (bigger than a golf ball) may cause repeated episodes of colic, seriously affecting the health of the resident. They may require surgery. As far as preventing enteroliths, aside from preventing them from ingesting foreign material by keeping their living space clean, your veterinarian may suggest several changes to their diet, including reducing the mineral content of their diet. This can be done by first checking the mineral levels in any commercial food and supplements (and even the mineral level of their water) and making any necessary changes. They may also suggest avoiding wheat bran, which has a high mineral content, and reducing the alfalfa in their diet if it is particularly high. Grass hay and access to grass pasture are generally considered better when trying to reduce mineral content. Of course, the advisability of this depends on the health of the individual and the veterinarian’s recommendations.

Equine Gastric Ulcer Syndrome

Many factors can lead to ulceration of the stomach. Certain things like high-concentrate diets, fasting, NSAID use, or, in foals, interrupted nursing and laying down, correlate with the presence of Equine Gastric Ulcer Syndrome. Dietary measures to prevent gastric ulcer include a high forage diet, only supplemental additions of concentrates, and continuous access to forage. There are even some studies that indicate diets higher in alfalfa than bromegrass are associated with fewer cases of gastric ulcers. Of course, there are a number of other reasons a resident may need less alfalfa, so checking with a veterinarian will always be your best bet!

Equine Metabolic Syndrome

Generally speaking, a high fiber forage and low sugar/starch (no more than 10%) diet is recommended for residents with EMS. Supplements may need to be provided depending on the nutritional content of the forage. It is advisable to have the nutritional content of your available forage analyzed. Because they need lower levels of sugar in their diet, it is best to provide late cut grass hay as it contains less sugar. Hay should have 10-12% max in starch (less is better) and sugars. If you are uncertain about the starch and sugar levels in the hay that you have available, soaking the hay then draining off the water can reduce the amount of sugar they consume. Haylage may also be a possibility for some horses, but it shouldn’t be soaked as there is a risk of secondary fermentation. If you need to soak the hay to reduce the sugar/starch content, 30 minutes in hot water (or more time if soaking in cold water) is a good amount of time. However, soaking hay can also remove other nutrients that are important for the resident, so care must be taken to supplement these nutrients when necessary. Forage should be analyzed to allow you and your veterinarian to develop a precise diet plan, something that is vital for horses with EMS.

If a horse is underweight, beet pulp (unmolassed) may be a good choice for avoiding sugar while boosting calorie intake. Beet pulp can also be soaked and drained to remove even more sugar even though it is usually already low in sugar. Soy hulls can also be used to avoid sugar while providing calories. Access to pasture should be carefully planned. If given access, they should be given access in the early morning to limit the amount of fructan they consume. To prevent over-consumption, grazing muzzles can be used. Some horses may do better on a dry lot.

Once you have developed a plan with your veterinarian, you will need to ensure that both concentrates and hay are weighed and offered in the correct amounts. A digital scale can help ensure your resident is getting exactly what they need. If a resident has pasture access, a grazing muzzle (as mentioned above) can help ensure they don’t consume too much grass. Slow-feeder hay nets and other specially designed products can also slow their intake.

Exertional Rhabdomyolysis, Or “Tying-Up” 

Exertional Rhabdomyolysis is a potentially life-threatening disease that primarily affects horses used in sports or for intense labor. A sanctuary should not place residents in such potentially harmful situations. However, it is possible that a resident who was previously used in such situations and developed this health condition could be more prone to repeat occurrences. It could even occur if a resident is being chased by other residents. Additionally, there are a number of non-exertional causes as well, but we will go into that later. This condition can be triggered by an unbalanced diet or stress. Signs of exertional rhabdomyolysis include muscle stiffness, unwillingness to move their body due to muscle pain and cramping, as well as excessive sweating. In some cases, urine may be brown and they may have increased heart and respiratory rates.

Chronic ER is further broken down into two different disease processes: Recurrent exertional rhabdomyolysis (RER) and Polysaccharide storage myopathy (PSSM). Each has a different cause and results in different symptoms.

While there are still some uncertainties about the causes of these processes, there has been research that points at certain possibilities. Some research points to abnormal regulation of calcium within the cells of muscles as being the cause of RER. It is believed that horses suffering from PSSM are unable to appropriately use the sugar within those muscle cells, which cause the muscles to “starve”, causing serious damage when they exert a lot of energy.

To further complicate things, there are actually two types of PSSM: PSSM I is associated with genetics, while the cause of PSSM II is unknown.

Quarter horses and paint horses may also inherit a genetic condition called malignant hyperthermia (MH). Similar to PSS in pigs, this condition can be triggered by stress, excitement, or by being exposed to certain anesthetics or succinylcholine (a muscle relaxant). Horses that are affected by genetic malignant hypothermia may have more severe cases of ER if they also have the PSSM Type I gene mutation. Myofibrillar Myopathy (MFM) is another type of exertional rhabdomyolysis that presents with similar clinical symptoms but has a different underlying cause that is being studied. 

In terms of appropriate nutrition for horses with exertional rhabdomyolysis, a diet that is lower in starches and sugars is ideal (while still providing a well balanced diet). It can help prevent issues with vitamin deficiencies or electrolyte imbalances. Steps should be taken to prevent undue exertion in residents with this condition. If they are active, particularly if their activity causes them to sweat, then ensuring they have balanced electrolytes (sodium, calcium, and potassium) is crucial.

Vitamin E can be added to their diet for added benefit to muscle health, specifically the strength of their muscle membrane and preventing the leaking of enzymes from the muscle. Talk to your veterinarian about the appropriate dosage and types of vitamin E to supplement, as synthetic and natural sources have different levels of absorption. Vitamin E can be provided with nice green grass or quality hay, as well as through supplementation of rice bran. 

Selenium is also an important nutrient for maintaining muscle health, and care should be taken that their diet is not deficient in either of these areas. Many pastures produce grass with low selenium levels. The selenium levels in the soil can be tested to give you a better idea of how much selenium may need to be supplemented. There are some commercial diets available for horses with ER. The easiest way to determine whether a resident’s vitamin E and selenium levels are adequate is through blood/serum testing.

Horses with PSSM store more glucose in their muscles and are more sensitive to insulin, so limiting the amount of starch and sugar in their diet to 10-15% is an important aspect of dietary management of this disease. Horses with RER can generally have a little more, up to 20% in their diet. With lower percentages of sugars and starches being provided, you’ll want to be sure they still have the right amount of energy provided in their diet. Supplementing easily digestible fibers, such as low-carbohydrate soy hulls or beet pulp, can increase the density of the diet, as can supplementing with oil or rice bran for added fats. There is research that suggests that providing horses prone to exertional rhabdomyolysis a low carb/higher fat diet can reduce the number of recurrences. It is possible that, because there are easily accessible amounts of fat that can be used for energy, this reduces the body’s heightened response to insulin. This translates as less glycogen storage in muscle cells, which is particularly helpful for horses with PSSM.

Immune-Mediated Myositis (IMM) 

Immune-Mediated Myositis is an autoimmune disease that generally affects horses under 8 or over 17. While there is a genetic component, stress to the body, particularly through infection, can trigger IMM. It is characterized by sudden muscle wasting; up to 40% of muscle can atrophy within just 48 hours.This is seen along a horse’s topline and hindquarters. Other possible symptoms include fever, depression, stiffness, difficulty standing, and loss of appetite. A veterinarian may recommend steroids and antibiotics to stop the atrophy of the muscles. It is important that horses afflicted with IMM are fed a high quality concentrate with protein and a good balance of vitamins and minerals. Alfalfa and amino acids supplements can provide additional support while muscles are built back up.

Insulin Resistance

The bodies of horses with insulin resistance don’t respond normally to insulin. Generally speaking, a high fiber forage and low sugar/starch (no more than 10%) diet is recommended. Supplements may need to be provided depending on the nutritional content of the forage. It is advisable to have the nutritional content of your forage analyzed. Because they need lower levels of sugar in their diet, it is best to provide late-cut grass hay, as it contains less sugar. Hay should have 10-12% max in starch and sugars. If you are uncertain about the starch and sugar levels in the hay you have, soaking the hay then draining off the water can reduce the amount of sugar they consume. Some hay has more starch and sugar content than others. Alfalfa and bluestem hay are low compared to barley or oat hay, or wheat and rice bran, which should not generally be fed to a horse who is insulin resistant. 

Haylage may also be a possibility for some horses, but it shouldn’t be soaked as there is a risk of secondary fermentation. If you need to soak the hay to reduce the sugar/starch content, 30 minutes in hot water (or more time if soaking in cold water) is a good amount of time. However, soaking hay can also remove other nutrients that are important for the resident, so care must be taken to supplement these nutrients when necessary. Forage should be analyzed to allow you and your veterinarian to develop a precise diet plan, something that is vital for horses with insulin resistance.

When possible, limit or completely eliminate calorie-dense foods from their diets. This included grains (oats, barley, corn) and sweet feeds. Because you will be feeding a low quality hay, you will need to add a ration balancer that provides their vitamins and minerals, particularly vitamin E, zinc, and copper. Alternatively, you can now offer commercial low starch/sugar, high fiber forage-based feeds that have added minerals and vitamins. Beet pulp has low sugar content and can be considered as a part of a resident’s diet. Feeding smaller meals throughout the day will help to prevent their insulin levels from peaking.

Once you have developed a plan with your veterinarian, you will need to ensure that hay and any commercial foods are weighed and offered in the correct amounts. A digital scale can help ensure your resident is getting exactly what they need. If a resident has pasture access, a grazing muzzle (as mentioned above) can help ensure they don’t consume too much grass. Slow-feeder hay nets and other specially designed products can also slow their intake.

Kidney Dysfunction

In cases where a horse is experiencing kidney dysfunction, it is often recommended that care be taken to restrict intake of protein, phosphorus, and calcium. As you can see, the recommendations are different for a horse with non-disease related weight loss and weight loss related to kidney dysfunction. This is an excellent example of why health checks are so necessary before changing a horse’s diet and highlights the need for expert guidance. Providing a diet higher in protein for a horse with kidney disease could cause much more harm. If the horse is a senior, complete feeds that are designed for seniors are NOT recommended due to the increased protein content. Instead, a complete feed maintenance diet for adults is generally considered safer. 

Because legumes (clover and alfalfa), beet pulp, and wheat bran contain higher levels of either calcium, phosphorus, or protein, they should generally be avoided as well. Grass hay, milo, and corn may be better alternatives for comprising their diet.

Laminitis

Laminitis is all too common among our horse friends and it can be difficult to watch as they deal with this painful disease. It affects the sensitive and insensitive tissues in the foot that support the pedal bone. When these tissues lose blood flow,  become inflamed, or break down, the coffin bone can detach from the wall and sink; this can be debilitating and sometimes fatal. While there are many possible causes of laminitis, diet can play a large part in the development and management of the disease. We will focus on diet-related causes and management here.

Diet-Related Factors Of Laminitis:

  • Access to lush pastures 
  • Carrying excess weight
  • Eating a diet high in concentrates
  • Food binges (accessed a grain bin or lush pasture and ate large amounts)

General Diet Tips For Avoiding Laminitis:

  • Help horse residents maintain a healthy weight.
  • Avoid letting residents onto pastures with fresh spring grass.
  • Try to feed residents hay in the morning and give them access to the pasture once the dew has evaporated. Early morning and dusk are when grass has the highest sugar content.
  • Avoid diets high in concentrates.
  • Always be sure to keep food bins securely closed and out of reach of residents.
  • Always make gradual changes to a resident’s diet.

If a resident has laminitis, it is vital that you develop a diet plan with an experienced veterinarian. There are different considerations depending on the cause of the disease, and if you attempt to design a diet without veterinary guidance, you risk causing serious harm to the resident. Generally speaking, a high fiber forage and low sugar/starch (no more than 10%) diet is recommended. Supplements may need to be provided depending on the nutritional content of your forage. Because they need lower levels of sugar in their diet, it is best to provide late-cut grass hay as it contains less sugar. If you are uncertain about the starch and sugar levels in the hay you have, soaking the hay then draining off the water can reduce the amount of sugar they consume. Haylage may also be a possibility for some horses, but it shouldn’t be soaked as there is a risk of secondary fermentation. Horses will need mineral and vitamin supplementation based on the deficiencies of the forage provided. Horses with excess weight or a stable weight can be given minerals with chaff (low sugar). If a horse is underweight, beet pulp (unmolassed) may be a better choice for adding mineral supplements. Beet pulp can also be soaked and drained to remove even more sugar even though it is usually already low in sugar.

Horses with endocrine laminitis (or those who have insulin dysregulation, equine metabolic syndrome, or Cushin’s disease) may do best with a 10% max sugar/starch diet that is provided in smaller amounts throughout the day in order to prevent their insulin levels from peaking. The amount of grass they can have will depend on their insulin levels.

Laminitic horses with Cushing’s disease may require more nutrients. Protein content in their diet may need to be raised if they are experiencing muscle loss. If a horse with Cushing’s disease doesn’t also have insulin deregulation, then they may be able to have a diet higher in sugar and starch. Zinc, copper, Vitamin E, and selenium may be nutrients your veterinarian recommends for laminitic horses with Cushing’s disease.

When considering concentrates for a laminitic horse, always check the digestible energy content. If the horse you are caring for is carrying excess weight, they shouldn’t have concentrates that are high in digestible energy. A veterinarian may recommend a lower calorie commercial food or a ration balancer pellet. 

If the laminitic horse being cared for is insulin-resistant, avoid feeding any concentrates that have a high sugar/starch content and look for commercial foods that are specially designed to contain lower amounts of sugar and starch.  

When considering hay, it is always best to have it analyzed if at all possible. This way you can be confident about the amount of sugar/starch and various nutrients the resident is receiving. This can help you and your veterinarian or equine nutritionist develop a better diet plan for the individual. If you need to soak the hay to reduce the sugar/starch content, 30 minutes in hot water (or more time if soaking in cold water) is a good amount of time. However, soaking hay can also remove other nutrients that are important for the resident, so care must be taken to supplement these nutrients when necessary. If a laminitic horse is carrying excess weight, you may need to lower their forage intake to 1.2-1.5%. Check with your veterinarian before implementing these changes. 

For laminitic horses, it is important that the amount of food they consume is precise. Once you have developed a plan with your veterinarian, you will need to ensure that both concentrates and hay are weighed and offered in the correct amounts. A digital scale can help ensure your resident is getting exactly what they need. If a resident has pasture access, a grazing muzzle can help ensure they don’t consume too much grass. Slow-feeder hay nets and other specially designed products can help slow their intake as well.

Liver Disease

Horses with liver disease may present with a number of symptoms, such as lethargy, jaundice, colic, fever, and abnormal behaviors such as head pressing, circling, lack of coordination, sudden confrontational behaviors, increased friendly behavior, and other neurological symptoms. They may also experience edema, swelling of their legs and the bottom of their abdomen and chest. Some horses may also develop photosensitization and require extra protection from the sun. 

Liver disease is serious and can be fatal. Always design a diet for a resident with liver disease with your veterinarian as the individual’s dietary needs may vary. Here are some general dietary changes that may be recommended:

  • Feed a high starch diet
  • Reduce protein intake
  • Avoid alfalfa and clover
  • Feed good quality grass hay and/or pasture
  • Avoid foods high in fat
  • Offer foods with good branched amino acid chains (such as beet pulp, corn, sorghum, wheat bran, and milo)
  • Ensure they are receiving the appropriate vitamins and minerals
  • Offer small meals throughout the day

Metabolic Disorders 

Some senior horses may develop metabolic conditions as they age. Conditions such as Cushing’s disease, equine metabolic syndrome or insulin resistance (discussed in greater detail above) can require a number of treatment strategies, including feeding a specialized diet. 

Diets for individuals with metabolic disorders generally focus on keeping insulin levels stabilized. In terms of diet, this means providing diets with low starch and sugar content, but high in easily digestible fats and fibers. To accomplish stable insulin levels, it is often recommended to offer quality forage, and digestible fibers such as soy hulls or beet pulp (without molasses!), and fat supplementation when necessary. Excess weight can be an issue for individuals with metabolic conditions and will need to be taken into consideration for many individuals. A veterinarian may recommend a ration balancer to ensure the individual’s protein, vitamin, and mineral requirements are met. A common tip for removing extra sugar from their diet is soaking their hay for 30-60 minutes (30 if hot water, 60 if cold) then draining the water off to reduce sugar intake.

Non-Exertional Rhabdomyolysis

I know, I know, you thought we were done discussing rhabdomyolysis! However, non-exertional rhabdomyolysis (NER) has clinically similar symptoms that are brought on by causes other than exertion. Horses that develop NER have a genetic component that may predispose them to developing this disease when triggered by certain environmental stimuli. 

NER can be caused by a mutated gene called MYH1. Mutations to the MYH1 gene can cause horses to present with NER or Immune Mediated Myositis. We cover Immune Mediated Myositis elsewhere. Horses with NER will present with muscle damage that is not connected to exercise, and a veterinarian can confirm the diagnosis by checking the levels of serum creatinine kinase levels, which will be high. Even with these levels, the afflicted horses may not present with muscle atrophy. NER occurs more commonly in younger horses. Many horses develop this disease when it is triggered by bodily stress from infections or vaccinations for equine influenza, steptococcus, or equine herpesvirus 4.

A diet consisting of a good balance of vitamins, minerals, and high-quality protein (such as soybean meal) is generally recommended during recovery. 

Vitamin E can be added to their diet for added benefit to their muscle health, specifically the strength of their muscle membrane and preventing the leaking of enzymes from the muscle. Talk to your veterinarian about the appropriate dosage and types of vitamin E to supplement, as synthetic and natural sources have different levels of absorption. Vitamin E can be provided with nice green grass or quality hay, as well as through the supplementation of rice bran. 

Selenium is also an important nutrient for maintaining muscle health, and care should be taken that their diet is not deficient in either of these areas. Many pastures produce grass with low selenium levels. The selenium levels in the soil can be tested to give you a better idea of how much selenium may need to be supplemented. There are some commercial diets available for horses with ER. The easiest way to determine whether a resident’s vitamin E and selenium levels are adequate is through blood/serum testing.

Pituitary And/Or Thyroid Tumors (See Cushing’s Disease)

For horses with pituitary or thyroid tumors, diets can be modified to better support the individual. Generally speaking, a veterinarian may recommend reducing the starch in their diet while providing sources of fiber that are easily digestible, and even the addition of vitamin C supplements if they experience chronic infections. Food choices for these individuals may include a diet with low molasses content but high fat and fiber content, quality forage (so long as the individual does not have laminitis), and supplements to promote healing in the case of secondary infections. 

Poor Dentition

Always be sure to have a veterinarian check the mouth, gums, and teeth of residents and have their teeth floated yearly. This can help you identify issues before they become serious and help you design a diet that is suitable for the individual’s needs.

For horses with dental issues, it can be helpful to provide food that is easily chewable and digestible, such as soaked beet pulp, hay cubes, or making a thick “soup” with a complete pelleted or extruded foods. Offer soaked, chopped hay to help them chew their forage and choose softer hays when possible. Always be sure to have a veterinarian check the mouth, gums, and teeth of residents and have their teeth floated yearly.

Poor Gut Absorption

This condition is more often seen as horses age. A good deworming protocol is important because parasites compete for nutrients, limiting the amount of nutrients absorbed by the horse resident, while also potentially causing damage over the years with intestinal scarring that may make it harder for horses to absorb all the nutrients they need. Research has documented that senior horses absorb vitamins, proteins, and phosphorus at a lower level. Without the ability to absorb as much protein, senior horses may present with muscle wasting as protein is needed to keep muscles in good shape. In this case, adding more protein to their diet is vital to keep them healthy and happy. A good percentage of protein in forage and food is around 14%. In addition to a decreased ability to absorb protein, their body may produce less of the important enzyme to break down starch, which would mean too much starch could get into their hindgut, making them more susceptible to colic and laminitis. 

Recurrent Airway Obstruction (RAO), or “Heaves”

RAO, also known as “Heaves”, is a disease sometimes referred to as Equine Asthma. There are two types of RAO, Summer Pasture-Related RAO and Barn-Related RAO. Both require dietary management. Horses with Barn-Related RAO should be kept out of dusty stalls as much as possible and given access to pasture when possible. A diet of fresh grass (assuming they don’t have other health issues that interfere with this diet), supplemented with any commercial food to avoid nutritional deficiencies, will help manage the disease. There are other environmental management strategies that can help as well, such as storing any hay in a separate building and avoiding the use of any bedding that is prone to putting particles in the air. If you must feed hay, avoid round bales as they may carry more irritating allergens. Horses may need their hay soaked or steamed to prevent irritating particles from reaching their respiratory tract. Some may do better with soaked cubes or “mash”. 

Horses with Summer Pasture-Related generally need to be kept off pasture unless it is winter. Spring and fall pasture access may be okay for these horses as well, depending on your region and the presence of irritating allergens. Hay should preferably be stored in a different structure from where a resident with SPRAO is living, and dusty bedding should not be used. 

Omega-3 fatty acids may also be recommended by your veterinarian for both conditions.

Weight Loss And Muscle Loss 

This addresses weight loss that is not associated with specific health issues (such as liver or kidney dysfunction), as these diseases require specialized diets and treatments different from those that follow. For a generally healthy horse (particularly a senior horse) who has trouble keeping on weight or in whom you have noticed muscle loss, the general recommendations for promoting healthy weight gain or maintenance include increasing the protein and fat content of their diet and ensuring forage and concentrates are easily chewed and digestible. Offering grass or hay mixed with grass, providing access to quality pasture, and possibly supplementing their diet with brewer’s yeast, vegetable oil, soybean meal, and/or beet pulp, along with complete or extruded feeds can help put and keep weight on horses with weight loss. 

  • Beet pulp is often used because it is a source of easily digestible fiber. It is sometimes incorporated into commercial feed, or it can be bought separately to be wet down and fed in addition to grain.
  • When selecting commercial foods for digestibility, look for foods that contain grains that have been through a process of rolling or steam flaking, or crimping or cracking. These processes improve the digestibility of the grains by breaking the seed’s coat. 
  • Supplementing a diet with fat can be accomplished in two ways: though feeding commercial products with added fat contents, or by adding high fat supplements (generally vegetable oil) on top of the horse’s food. When adding fat to the diet by adding vegetable oil, it is very important to be aware that this will result in less food being required, so focus should be given to ensure that protein, vitamin, and minerals are also increased to prevent an imbalance in their diet. If choosing to supplement fat with vegetable oil, it is imperative to do this under the supervision of a veterinarian or nutritionist, as they can recommend the correct amounts of protein, vitamins, and minerals that the horse will need. Health checks will also prevent situations where a change in diet causes harm. In the case of high fat diets, if a horse is experiencing liver dysfunction, a high fat diet is not appropriate for them.

While this is not an exhaustive list of the dietary needs of horse residents with health conditions, hopefully it has given you an idea of what factors to consider when designing diet plans (with your veterinarian and equine nutritionist) for your horse residents.

SOURCES:

5 Equine Nutrition Disorders Horse Owners Should Know | Kentucky Equine Research (Non-Compassionate Source)

Using Nutrition To Prevent And Manage Equine Disease | The Horse (Non-Compassionate Source)

Your Horse’s Diet As It Relates To Diseases And Conditions | EquiMed (Non-Compassionate Source)

Tying-Up In Horses | Rutgers Cooperative Extension (Non-Compassionate Source)

MYH1 Myopathy: Immune-Mediated Myositis / Nonexertional Rhabdomyolysis | UC DAVIS Center For Equine Health

Equine Gastric Ulcer Syndrome | American Association Of Equine Practitioners. (Non-Compassionate Source)

Malignant Hyperthermia (MH) | UC Davis Veterinary Medicine

Myofibrillar Myopathy (MFM) | Equiseq  (Non-Compassionate Source)

Enteroliths In Horses | Kentucky Equine Research (Non-Compassionate Source)

What To Do About Enteroliths | Equus  (Non-Compassionate Source)

IMM – Immune Mediated Myositis And MYH1 Myopathy | Animal Genetics (Non-Compassionate Source)

Myosin Heavy Chain Myopathy (MYHM) | MSU College Of Veterinary Medicine (Non-Compassionate Source)

Diarrhea In Horses | VCA  (Non-Compassionate Source)

Nutritional Support Of Horses With Liver Disease | Kentucky Equine Research (Non-Compassionate Source)

Nutritional Management Of Insulin Resistance In Horses | The Horse (Non-Compassionate Source)

Glycemic Index Among Horse Feeds | Kentucky Equine Research (Non-Compassionate Source)

Senior Horse Nutrition | The Horse (Non-Compassionate Source)

Taking Care of the Senior Horse | Kentucky Equine Research (Non-Compassionate Source)

Care For The Older Horse: Diet And Health | Recent Advances In Equine Nutrition  (Non-Compassionate Source)

Caring For The Older Horse: Common Problems And Solutions | University of Georgia College of Agricultural and Environmental Sciences Cooperative Extension (Non-Compassionate Source)

Recurrent Airway Obstruction (RAO) In The Horse | American Association Of Equine Practitioners

Equine Applied And Clinical Nutrition E-Book: Health, Welfare And Performance | Google Books (Non-Compassionate Source)

Non-Compassionate Source?
If a source includes the (Non-Compassionate Source) tag, it means that we do not endorse that particular source’s views about animals, even if some of their insights are valuable from a care perspective. See a more detailed explanation here.

Updated on October 14, 2020

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