Equine Metabolic Syndrome vs Equine Cushing’s Disease

Written by: Amber Long, West Bladen High School FFA President

 

Equine Metabolic Syndrome

Equine Metabolic Syndrome (EMS), or Insulin Resistance, is a disorder of carbohydrate metabolism that is usually seen in overweight, middle-aged horses. It is associated with severe laminitis. These horses may build up a high level of cortisol. Increased circulating levels of cortisol increase blood sugar and inhibit the uptake of glucose into cells by antagonizing the action of insulin. Persistent high blood sugar is known to be toxic and it is possible that it contributes to laminitis in horses by damaging the blood vessels in the hoof.

Clinical signs include:

•  Laminitis – typically begins in the spring with rapid growth of grass 
•  General obesity with regional and/or regional adiposity 
•  Crusty neck, fat deposits around the tail head, sheath and suborbital fossa (hollow above the eyes), occasional subcutaneous masses on the trunk

Resting insulin and blood sugar are the most common screening tests used to diagnose the metabolic syndrome. If you suspect that your horse has laminitis due to metabolic syndrome, schedule a physical exam with your veterinarian. You may also test your hay to determine the carbohydrate content. Straight alfalfa is not appropriate for these horses.

The goal of treatment is to improve insulin sensitivity and raise the threshold for laminitis. Metabolic Syndrome can be managed through diet and exercise.

Equine Cushing’s Disease

Equine Cushing’s disease is a disorder of the pituitary gland that results in hormonal imbalances. In affected horses, the pituitary gland is usually enlarged and overactive as a result of faulty regulation by the hypothalamus. This disease usually occurs in middle-aged and geriatric horses.

Clinical signs include:

•  A long, wavy hair coat that fails to shed according to normal seasonal patterns 
•  Excessive sweating 
•  Lethargy and poor athletic performance 
•  Chronic recurrent laminitis 
•  Infertility 
•  Weight loss 
•  Muscle wasting, especially along the topline 
•  Abnormal distribution of fat, with accumulations in the crest of the neck, tail head, sheath, and above the eyes 
•  Consumption of large volumes of water and passage of large amounts of urine 
•  Delayed wound healing 
• Increased susceptibility to infections

In advanced cases, diagnosis is straightforward. However, diagnosis of early cases or those with few obvious clinical signs is more difficult. Two commonly used tests are: the dexamethasone suppression test and measurement of plasma ACTH concentration.

Managing Cushing’s disease involves both specific medication to normalize the function of the pituitary gland and supportive care to address and prevent complications associated with the disease. Management will be life-long because there is no way to reverse the disease process.

For additional information, visit these articles: Equine Endocrinology: Cushing’s Disease and Metabolic Syndrome from the American Association of Equine Practitioners, Insulin resistance in horses from University of Minnesota Extension, and Management of Equine Cushing’s Disease and Equine Metabolic Syndrome from the University of Florida.

Flood Damaged Pasture and Hay

Heavy rains and flooding have devastated much of our state over the past week.  As many of us begin the process of recovering, one thing to consider is the condition of our pasture land and hay.  If your farm was impacted by hurricane Matthew, there are several things you may need to consider over the course of the next week.

Flooded pastures pose several dangers to horse owners.  Before allowing horses to return to the pasture, take a walk and assess the condition of the pasture.  There may be debris in your pasture, which should be removed before horses return.  Make an assessment of how wet the pasture is.  Turning horses out onto pasture which is too wet can cause hoof problems and will also lead to pasture damage and soil compaction.  Sandy soils will drain quickly, but heavier soils may need a week or longer after flood waters recede before draining to an acceptable level. 

Assess forage quality and be sure forages have regained a dark green color.  Flooding causes extreme stress to forages.  Some may not recover and replanting may be necessary for many.  Others will recover, but should not be grazed until they are allowed time to resume growth.  Some damaged forages may mold and begin to decay.  Moldy and decaying forages should be removed by mowing and should not grazed.  Be sure to wear a dust mask, as these mold spores cause respiratory issues. 

Sediment is the largest source of pollution in North Carolina waters, and flood waters often leave behind large amounts of sediment.  Sediment left behind in pastures can lead to sand colic and be deadly.  Sediment deposits will be washed from the leaves with the next rain event, or areas with sediment can be removed by mowing.  After mowing, be sure to only graze new growth, rotating horses to different areas of the pasture before they graze low into the contaminated forage.

Hay which has been damaged by flooding will likely be unusable.  Wet hay can be dangerous, as high moisture levels can lead to heating, and even combustion.  Be sure to spread out wet hay as soon as possible to prevent heating.  Wet hay should not be used for consumption, but can be used for other purposes on the farm, such as erosion control.  Damaged hay can also be spread out over hay fields as a fertilizer.  Keep in mind that hay will wick water, so if bales are stacked, remove layers which came in contact with flood waters, but also check layers above for moisture damage.  Again, a dust mask should be worn when handling moldy hay, as these spores can cause serious respiratory illness when inhaled.  There will likely be a need for hay this winter, so if you have hay available or need hay, post or check online at http://www.ncagr.gov/hayalert/ or contact your extension agent.  

If you have questions about flood damages, contact your extension office.  If you experienced hay losses on you farm, be sure to document losses and take photos of the bales and place where the bales were stored.  Contact your local Farm Service Agency (FSA) office to ask about emergency assistance programs for hay losses.

Winter Hay Supply

The green summer pastures are slowly turning brown letting us know it will soon be winter. Good quality hay is an important part of a horse’s winter diet. Knowing how to select good quality hay, how to calculate the amount of hay needed, and how to properly store hay will ensure your horses will have hay throughout the winter.

Selecting Good Quality Hay

Visual and chemical analysis are two tools that can be used when selecting hay. Visual analysis includes the color, odor, texture, leafiness, and presence of foreign material. Generally the greener the hay the better, indicating a high vitamin and protein content. Generally as hay browns there is a loss of nutrients, but don’t choose hay on color alone. Bleaching from the sun can cause the outside of the bale to brown while the inside of the bale is still green. The odor of hay can uncover the presence of mold, usually caused by improper curing or storage. Mold typically appears as a grayish-white dust and can become flaky in tightly packed sections of the bale. Hay texture and leaf to stem ratio can be indicators of the nutritional value and quality of hay which is affected by the maturity of the grass when it was cut and baled. Immature hay is more easily digested by horses because as grass matures, the nutritional content begins to decrease. As grass matures stems become tougher and thicker and the leaf to stem ratio decreases. Hay texture is an important factor in palatability because horses prefer small, flexible stems as opposed to tough, thick stems. Leaves contain more digestible carbohydrates than stems, therefore the more leaves that are present the better. Foreign material is anything in the bale that is not the forage you intend to purchase. Look for weeds, insects, mold, and trash.

A chemical analysis can also be done. This is the only true indicator of the nutritional quality of the hay. It is recommended that all hay be tested before feeding to ensure that the hay is safe and providing adequate nutrients. Many of those who sell hay will have it tested, so you can ask to see the analysis results. Your local Extension agent can help you take a hay sample and get that sample tested.

Calculating the Amount of Hay Needed

Horses will eat 1.5-2.5% of their body weight everyday in dry matter. You can figure out how much your horse will eat using the following equation. Ask your hay supplier for approximate bale weights.

Horse weight (lb) x (percent daily intake of dry matter ÷ 100) = lb eaten/day Lb eaten/day x 365 days/yr = lb/year Bales/year = lb/year ÷ lb/bale tons/year = lb/year ÷ 2,000 lb/ton Example: A horse weighs 1,100 pounds and has a daily intake of 2%. Note the difference in bale weight plays in the total number of bales needed when the average bale weight is 35 pounds vs. 50 pounds. 1,100 lb x (2% ÷ 100) = 22 lb hay/day 22 lb/day x 365 days/year = 8,030 lb/year Bales per year: 8030 lb/year ÷ 35 lb/bale = 230 bales/year                                                             8030 lb/year ÷ 50 lb/bale = 160 bales/year Tons/year: 8030 lb/yr ÷ 2000lb/ton = 4 tons/year

Hay Storage

Knowing how hay was stored prior to purchase and how it will be stored after purchase is key to making sure there is minimal loss. Hay left out in the elements is likely to lose nutritional value and become moldy. The best way to store hay is in a covered building and elevated up off the dirt. But any type of storage is better than leaving the hay directly on the dirt exposed to the weather.