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.
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 (non-structural carbohydrates), they are converted to fat which is stored in fat deposits including the top of the neck. Over time, this area becomes enlarged and hardens.
Sugar and starch are found in lush grasses, hay, grains, concentrates, and treats. High NSC 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. 
Horses with cresty neck may or may not have general 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. 
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, and Warmbloods 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. 
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)
Regional adiposity, such as a cresty neck, is thought to be the strongest identifier of EMS. 
EMS is also linked with obesity and insulin resistance (IR). It prediposes horses to laminitis that is not caused by grain overload, colic, or limb 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. 
When EMS horses consume a high-NSC 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. 
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 thyroid releasing hormone. 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.
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 System
Cresty necks are scored as follows: 
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 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. 
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. 
Fat distribution is also affected by sex hormones. Stallions tend to have a greater deposition of fat along the neck crest compared to mares or geldings.
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 non-structural carbohydrate (NSC) forage-based diet. Less than 10% NSC 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 with those with cresty neck. 
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. Replacing a portion of your horse’s hay with straw can also help to lower the energy density of the diet.
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 and Summer. They should instead be restricted to a dry lot and fed a diet of grass hay.
Once cresty neck and insulin resistance are under control, these horses may be able to tolerate some pasture, but grass intake will likely need to be monitored for the rest of their life.
Having your forage tested to measure the NSC content is best. Soaking hay in cold water for 60 minutes can reduce the sugar content by approximately 30%.
It should be noted, however, that soaking hay can also result in the loss of the minerals potassium, sodium, magnesium, calcium, and phosphorus. Therefore, these minerals will all need to be supplemented. 
A high-quality ration balancer or equine vitamin and mineral supplement may be your best option for this.  Most ration balancers are low in NSCs but if you’re unsure, check with the manufacturer.
Mad Barn’s AminoTrace+ supplement is a low-NSC 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.
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. 
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. 
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 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 can enhance insulin sensitivity and may also help to prevent horses from becoming insulin resistant later in life.
The horses supplemented with chromium in the study had lower plasma glucose concentrations than horses that didn’t receive the supplement. 
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.  Supplementation with magnesium has shown improvements in glucose tolerance in horses , humans and animal models .
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 proven to support metabolic health in horses.
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. 
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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