An overabundance of fat along the top of the neckline, otherwise known as cresty neck, is an indicator of metabolic problems in your horse.

In fact, researchers believe this type of regional fat deposit (nuchal crest adiposity) is a strong indicator of equine metabolic syndrome (EMS).

Recognizing cresty neck in your horse early on is important as EMS can put your horse at risk for developing the potentially debilitating disease, laminitis.

If your horse has already developed a cresty neck, the good news is that there are measures you can take to reduce this fat accumulation. Feeding, exercise, and management practices can all help to get rid of a cresty neck because they improve insulin sensitivity.

By doing so, you will also reduce your horse’s chance of developing other complications related to metabolic disease. For help with addressing your horse’s cresty neck, submit their information and feeding program for analysis online.

What Causes Cresty Neck in Horses?

Horses that have cresty neck are usually described as easy keepers or over-conditioned.

In addition to being overweight, horses with a cresty neck may have some form of metabolic dysfunction or insulin resistance.

When there is too much sugar or starch in the diet (hydrolyzable carbohydrates), they are converted to fat which is stored in fat deposits including the top of the neck. Even some of the volatile fatty acids produced during forage fermentation can be converted to fat. Over time, this area becomes enlarged and hardens.

Simple sugars and starch are hydrolyzable carbohydrates (HC). This means they can be digested and absorbed in the small intestine, contributing to insulin peaks. Insulin promotes fat storage in specialized cells called adipocytes.

Sugar and starch are found in lush grasses, hay, grains, concentrates, and treats. High HC feeds can contribute to and exacerbate cresty neck size.

Researchers are not exactly sure why horses develop this adiposity along the top of the neck. However, they believe that it may be a repository for long-term fat storage.

Horses with cresty neck may also develop fat pockets over the tail head, above the eyes, behind the shoulders, and/or around the sheath in the case of male horses. This fat tissue not only stores energy but also synthesizes and secretes hormones that affect metabolism and insulin function. [1]

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Prevalence

Horses with cresty neck may or may not have generalized obesity. One study found that obesity status (body condition score) and cresty neck condition were highly associated. In that study, 97.5% of obese horses and 59.6% of non-obese horses had cresty neck. [2]

There appears to be a genetic link to EMS and cresty neck, with certain breeds such as Welsh, Dartmoor, and Shetland ponies, as well as Andalusians, Morgans, Mustangs, Arabians, Haflingers, Icelandics and gaited breeds being more susceptible to insulin resistance.

These breeds tend to utilize glucose very efficiently, which ensures they have plenty of energy reserves when food is scarce. This also puts them at risk of greater fat accumulation if their diet supplies excess digestible energy. [9][10]

With that said, overfeeding, insufficient exercise, and mineral imbalances can all play a part in the development of cresty neck and it can occur in any breed.

Equine Metabolic Syndrome (EMS)

How to Get Rid of a Horse's Cresty Neck

Regional adiposity, such as a cresty neck, is thought to be the strongest external identifier of EMS. [1]

EMS is also linked with obesity and insulin resistance (IR). It prediposes horses to laminitis that is not caused by grain overload, colic, or overloading of a limb caused by injuries such as fractures. EMS horses may also have elevated triglyceride levels.

When horses are insulin resistant, this means that the cells in their muscles, fat, and liver do not respond well to insulin and take less glucose from the blood for energy. To make up for it, the pancreas then makes more insulin. Over time, blood sugar levels increase.

Senior horses aged 17-20 have higher blood insulin levels and lower insulin sensitivity than younger horses, which also puts them at risk for EMS. [3]

When EMS horses consume a high-HC diet, their bodies produce higher than normal levels of insulin and are slow to return to baseline values. These clinical signs were previously called hypothyroidism, peripheral Cushing’s disease, prelaminitic syndrome, or Syndrome X.

As mentioned previously, EMS horses are more susceptible to laminitis, which can be quite serious in some cases. In fact, up to 25% of equine euthanasia is associated with laminitis. [11]

EMS can be diagnosed by a veterinarian in one of several ways:

  • Blood glucose tests;
  • Blood insulin level;
  • Oral sugar test (OST);
  • Insulin tolerance test (ITT); and/or
  • Radiographs to confirm presence of laminitis or changes in the feet.

For older horses especially, it’s important to rule out PPID (formerly known as Cushing’s disease) by measuring ACTH concentration or their response to thyroid releasing hormone which causes an exaggerated ACTH level in PPID horses. However, horses can be affected by both EMS and PPID at the same time.

Scoring a Cresty Neck

Body condition scoring (BCS) has long been the most common method for assessing total body fat on a horse. Henneke’s nine-point scale is the most widely used scoring system for assessing BCS.

The Henneke body condition scoring system also lists a cresty neck as a sign of obesity. We have no way of knowing how many of the horses they looked at had EMS but cresty neck without obesity or a high cresty neck score indicate EMS.

Recently, researchers developed a way to measure neck crest fat with a 5-point scoring system known as the Cresty Neck Score (CNS). Horses are considered healthy with a score of 0-2, while a score of 3 or greater indicates metabolic dysfunction.

Cresty Neck Scoring for Horses

Cresty Neck Scoring System

Cresty necks are scored as follows: [12]

0 — No palpable crest.

1 — No visual appearance of crest but slight filling felt with palpation.

2 — Noticeable appearance of crest but fat deposited fairly evenly from poll to withers. Crest easily cupped in one hand and can be bent from side to side.

3 — Crest enlarged and thickened so fat is deposited more heavily in middle of neck than toward the poll, giving a mounded appearance. Crest fills cupped hand and begins losing side to side flexibility.

4 — Crest grossly enlarged and thickened and can no longer be cupped in one hand or easily bend from side to side. Crest may have wrinkles or creases perpendicular to the topline.

5 — Crest is so large that it droops to one side (called a fallen crest).

Implications of CNS

The Cresty Neck Score (CNS) is simple, but it does require an experienced person to give consistent scores.

One study showed that ponies with a CNS of 3 or greater were five times more likely to be insulin resistant than those with a CNS below 3. These scores were not related to the horses’ BCS. [1]

An interesting phenomenon with CNS scores is that they may change throughout the year. Another study found that CNS scores were higher at the end of winter months as compared to the end of the summer.

This is the opposite of general obesity; BCS scores tend to be highest after summer and lowest after winter months. [4]

Stallions have a prominent crest, but this is typically muscle sitting below the nuchal ligament while a pathological crest is fat deposited above the nuchal ligament.

Measuring the amount of fat along the nuchal ligament of the horse’s neck is not necessarily a good indicator of total body fat, but it can be used to predict metabolic conditions.

If you suspect that your horse has a cresty neck, have him or her evaluated by your veterinarian as soon as possible.

Addressing underlying metabolic issues, increasing exercise and feeding a lower-calorie diet will support weight loss and help you get rid of your horse’s cresty neck.

Once your horse has reached a moderate body condition score of 4-5, excess fat along the neck should be eliminated or significantly reduced.

Best Way to Feed Horses with Cresty Neck

For any horse with cresty neck, the first step is to remove concentrated feeds and lush pasture from the diet, as well as any high sugar treats. An equine nutritionist can help you identify which high-sugar and starch feeds should be removed from the diet.

Replace these with a low hydrolyzable carbohydrate (HC) forage-based diet. Less than 10% HC is best for these horses.

Using a grazing muzzle while horses are turned out can restrict grass intake and might be a helpful tool for managing over-conditioned horses and those with cresty neck. [13]

If your horse is obese, you may need to reduce the amount fed to 1.25% of the horse’s total bodyweight until weight loss is achieved. Mature grass hay is preferrable as the low calorie supply will support weight loss without as much restriction.

If you are feeding early growth hay and are unable to source a mature grass hay, consider replacing a portion of your horse’s hay with straw can also help to lower the energy density of the diet.

Always choose straw without seedheads and work with a nutritionist to ensure protein requirements are met.

Some horses with enlarged cresty neck (those with scores of 3 or more) may not be able to tolerate access to pasture at all, especially in Spring. They should instead be restricted to a dry lot and fed a diet of grass hay.

Grasses allowed to grow to full height and drop their seed have the lowest HC, but fall regrowth of young grass and cold stress in winter can lead to very high HC content. [19]

Once cresty neck and insulin resistance are under control, these horses may be able to tolerate some pasture, especially if they are being regularly exercised, but grass intake will likely need to be monitored for the rest of their life.

Having your forage tested to measure the HC content is best. HC is the sum of starch plus ESC on the hay analysis. Soaking hay in cold water for 60 minutes can reduce the sugar content by approximately 30% but this varies significantly and is not easily predicted. [22]

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Whether soaked or not, forage alone will not meet all vitamin and mineral requirements. [20] A high-quality ration balancer or equine vitamin and mineral supplement can ensure these requirements are met. [5] Most ration balancers are low in HC but if you’re unsure, check with the manufacturer.

Mad Barn’s AminoTrace+ supplement is a low-HC pelleted mineral and vitamin formula intended to meet the needs of metabolic horses. It is used by many horses with a history of cresty neck.

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  • Complete mineral balance
  • Supports metabolic health
  • Formulated for IR/Cushing's
  • Hoof growth

Exercise Program

Horses with cresty neck can also benefit from regular exercise, which will improve insulin sensitivity and promote weight loss.

According to one study, ponies exercised on a treadmill for six weeks showed improvement in insulin sensitivity. This improvement was maintained even after six weeks of reconditioning.

However, researchers in the study noted that dietary restriction combined with exercise may produce even better results. [5]

Lounging, riding, turnout in an arena or large dry lot, or even using a track system can all increase a horse’s movement and provide healthy exercise for horses.

Keeping your horse with other horses (as a herd) may also decrease cresty neck. With increased herd size, there is often greater competition for forage and higher activity levels, all which can be beneficial for EMS horses. [4]

Helpful Supplements for Cresty Neck

Certain minerals, including magnesium and chromium, have been found to support insulin sensitivity which may help reduce cresty neck in horses.

Chromium

Chromium is an essential trace mineral needed for energy utilization. In fact, glucose tolerance factor (GTF) is synthesized from dietary chromium. Furthermore, GTF binds to insulin to enhance its action within the body.

One study led researchers to conclude that supplementing 4 mg of chromium per day might enhance insulin sensitivity.

The metabolically healthy horses supplemented with chromium had lower plasma glucose concentrations than horses that didn’t receive the supplement. [6]

A similar study in known insulin resistant horses showed no change [21]. Further study in horses that are both insulin resistant and chromium deficient would be helpful.

Magnesium

Magnesium is crucial for healthy metabolic function and plays a role in carbohydrate, protein, and fat metabolism. Magnesium can support normal fat coverage in overweight equines, especially those with cresty neck.

Low cellular levels of magnesium are correlated with insulin resistance. [15] Supplementation with magnesium has shown improvements in glucose tolerance in horses [16], humans and animal models [17].

Magnesium Oxide is highly concentrated and readily absorbed by horses, making it a good choice for magnesium supplementation. It can simply be mixed in or top dressed over soaked hay, hay pellets or a ration balancer.

Mad Barn’s MagneChrome contains a number of quality ingredients, including magnesium and chromium, which are both known to support metabolic health in horses.

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Spirulina

Another supplement that has been found to be helpful for horses with cresty neck is spirulina.

Spirulina platensis is powdered, refined blue-green algae. It is high in antioxidants, including beta-carotene, vitamin C and vitamin E. It also contains anti-inflammatory fatty acids that support metabolic health.

In one study, three months of spirulina supplementation in EMS horses reduced cresty neck scores, improved insulin sensitivity and supported weight loss. The 6 EMS horses in this study had a cresty neck score of 4 before spirulina supplementation. For 5 of 6 horses, the score was reduced to 3 following supplementation. [18]

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  • Used in horses with allergies
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Summary

If your horse has developed cresty neck, it’s important to take measures as soon as possible in order to get rid of excess fat accumulation in the neck as well as other locations around the body.

Pay strict attention to diet, increase exercise if possible, and supplement with ingredients that can improve insulin sensitivity. By doing all of the above, you will also address the underlying metabolic condition which is causing cresty neck in the first place.

If your horse has a cresty neck, our nutritionists can help. Submit your horse’s diet online for a free evaluation and personalized advice on how to adjust your feeding plan.

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References

  1. Fitzgerald, D.M., et al. The cresty neck score is an independent predictor of insulin dysregulation in ponies. PLoS One. 2019.
  2. Martin-Gimenez T. et al. Beyond scoring systems: usefulness of morphometry considering demographic variables, to evaluate neck and overall obesity in Andalusian horses. Animal. 2018.
  3. Pleasant, R.S. et al. Adiposity, Plasma Insulin, Leptin, Lipids, and Oxidative Stress in Mature Light Breed Horses. J Vet Intern Med. 2013.
  4. Giles, S.L. et al. Assessing the seasonal prevalence and risk factors for nuchal crest adiposity in domestic horses and ponies using the Cresty Neck Score. BMS Vet Res. 2015.
  5. Morgan, R. et al. Equine metabolic syndrome. Vet Record. 2015.
  6. Spears, J.W. et al. Chromium propionate increases insulin sensitivity in horses following oral and intravenous carbohydrate administration. J Anim Sci. 2020.
  7. Bruyntsteen, L. et al. Expression of inflammation-related genes is associated with adipose tissue location in horses. BMC Vet Res. 2013.
  8. Severiano, S.R. et al. Correlations between cresty neck scores and post-mortem nape fat measurements in horses, obtained after photographic image analysis. Acta Vet Scand. 2016.
  9. Bamford, N.J. et al. Breed differences in insulin sensitivity and insulinemic responses to oral glucose in horses and ponies of moderate body condition score. Dom Anim Endocrin. 2014.
  10. Norton, E.M. et al. Heritability of metabolic traits associated with equine metabolic syndrome in Welsh ponies and Morgan horsess. Equine Vet J. 2018.
  11. Pollard, D. et al. Factors associated with euthanasia in horses and ponies enrolled in a laminitis cohort study in Great Britain. Prev Vet Med. 2020.
  12. Carter, R.A. et al. Apparent adiposity assessed by standardised scoring systems and morphometric measurements in horses and ponies. The Vet J. 2009.
  13. Becvarova, I. and Pleasant, R.S. Managing Obesity in Pasture-Based Horses. VetLearn.com. 2012.
  14. Bochnia, M. et al. Effect of Hay Soaking Duration on Metabolizable Energy,Total and Prececal Digestible Crude Protein and Amino Acids, Non-Starch Carbohydrates, Macronutrients and Trace Elements. J Equine Vet Sci. 2021.
  15. Winter, J.C. et al. Relationship between intracellular free magnesium concentration and the degree of insulin resistance in horses with equine metabolic syndrome. Pferdeheilkunde – Equine Med. 2020.
  16. Winter, J.C. et al. Oral supplementation of magnesium aspartate hydrochloride in horses with Equine Metabolic Syndrome.. Pferdeheilkunde – Equine Med. 2016.
  17. Bo, S. and Pisu, E. Role of dietary magnesium in cardiovascular disease prevention, insulin sensitivity and diabetes. Curr Opin Lipidol. 2008.
  18. Nawrocka, Daria et al. Spirulina platensis Improves Mitochondrial Function Impaired by Elevated Oxidative Stress in Adipose-Derived Mesenchymal Stromal Cells (ASCs) and Intestinal Epithelial Cells (IECs), and Enhances Insulin Sensitivity in Equine Metabolic Syndrome (EMS) Horses. Marine Drugs. 2017.
  19. Sharpe, P. Chapter 3 – Nutritional Value of Pasture Plants for Horses. IN: Horse Pasture Management. Academic Press. 2019.
  20. National Research Council Nutrient Requirements of Horses. 2007.
  21. Chameroy, K.A. et al. Effects of a supplement containing chromium and magnesium on morphometric measurements, resting glucose, insulin concentrations and insulin sensitivity in laminitic obese horses. Equine Vet J. 2011.
  22. Longland, A.C. et al. Effects of soaking on the water-soluble carbohydrate and crude protein content of hay. Vet Record. 2011.