Make sure and check this page frequently for updates. We will be posting brief articles on matters that concern your horse.

 RAIN ROT! 

It’s that time of year when the heat starts to rise as well as the humidity, and of course the showers and pop up rain storms Florida is known for.

The arrival of summer means changes in the management of our horses.  For most people, getting your horse in before the rain comes is not possible.  The reality is that our horses are going to get wet sometimes.  Add to that, the fact that a good roll when wet is a priority for most horses,  you have now created the perfect environment for Rain Rot to set in. 

Rain rot is a bacterial infection caused mainly by Dermatophilus congolensis.  It is also known commonly as rain scald, mud poisoning, or if only on lower limbs, dew poisoning.  These bacteria live in the soil and are commonly observed during prolonged periods of wetness.  The other factor that allows these bacteria to thrive is the anaerobic environment (absence of oxygen).  So when you horse is wet and dirty for long periods of time it increases the chance of Rain Rot.    

Infected horses generally will have a series of small bumps along their backs, rumps, neck and legs.  These lesions will progress to circular raised scabs or tufts of hair. Rain rot is contagious, generally transmitted by shared horse tack (such as blankets or brushes) or mutual rubbing posts such as a fence.  The lesions do not cause pain to the horses unless left untreated and a secondary skin infection results. 

Treatment centers on a few key management changes.  First, is the removal of the matted tufts of hair and scabs.  This can be is painful and result in raw, bleeding areas.  The bacteria do not survive once exposed to oxygen so removal of the scabs is the best treatment.  I recommend that you bath the horse with an antimicrobial shampoo (betadine or chlorohexidine shampoo) and soften the scabs before removal.  A good curry during the bath will remove the majority of the scabs and excess hair.  Don’t be concerned if you were unable to remove them all at one time, just bathe every other day until gone.  Second, disinfect your brushes as well so not to re-infect your horse when you are grooming them.  Wash them in the same shampoo and airdry them.  If your horse is still wearing a blanket, wash it as well and dry in the sun.  Wipe down your tack after every ride with a towel to remove excess dirt and hair.  Third, affected animals should be kept dry and clean as possible.  Limit turn out if there is a chance they will get wet.  A little extra elbow grease (grooming) to remove the excess hair in between bathing will help reduce the spread, get oxygen to the skin’s surface, and make your horse more elegant.  Severe cases may require treatment with antibiotics for a week or two.   

Just remember Warm sun and dry weather is nature's best cure for rain rot.

Aiding Horses with Gastric Ulcers

 

Gastric ulceration is the most common problem associated with the equine stomach.  It is caused by a combination of many factors from the management of the horse to the horses use.  It is reported that about 60% of show horses and up to 90% of racehorses suffer from gastirc ulcers.  One research study concluded that trailering a horse to a new place, keeping it is a stall for five days with light work and then bringing it home with no other changes in diet, can cause gastric ulcers.  Clinical signs of gastric ulcers can range from non-specific to severe.  Signs to watch for include:

Abdominal pain/discomfort

Decreased performance

Increase stress when taken off property

Mild to moderate colic

Poor body condition

Poor appetite, especially for grains

Loss of appetite when training

Frequent laying down

Changes in attitude/behavior

Decrease in performance                                       

 

The horse’s stomach is divided into two portions, the non-glandular and the glandular portions.  The non-glandular portion of the equine stomach is an area that is a reservoir for the food and does not secrete or absorb anything.  The glandular portion is very similar to the lining of human stomachs and is responsible for secreting hydrochloric acid, electrolytes and water.  The glandular area also has a thin lining of mucous that protects it from the acid it secretes but the non-glandular portion does not. At the division between the two areas is the margo plicatus.  Most ulcers are found on the non-glandular portion of the stomach next to the margo plicatus or possibly at the cardiac spincter (where the esophagus enters the stomach).

 

How to tell if your horse has Ulcers?

 

The only way to confirm that your horse has ulcers is to do a Gastroscopy.  The procedure is done at a clinic under light sedation.  The night before the horse must be held off all feed. This is the most important step as it allows the stomach to completely empty and gives the veterinarian the best chance to visualize the entire stomach lining.  Then, under light sedation, the veterinarian will pass a 3 meter endoscope into the nostril, down the esophagus and into the stomach.  Once there, we can visualize the gastric mucosa and evaluate it for the presence of ulcers.   Repeat gastroscopy may be necessary to insure the ulcers are healing post treatment.

What to do next?

 

If your horse is diagnosed with gastric ulcers, the best treatment is Gastroguard (Omeprazole).  Many management factors can help lessen the chance of horses getting ulcers.  One is turning your horses out on grass pastures. Others include, feeding hay more frequently (so there is less acid in the stomach), decreasing the amount of grain fed and increasing the roughage fed, and adding or increasing the amount of alfalfa hay in the diet (as this buffers the pH of the stomach).  

If you have any questions, please call Dr. Farmer @ 407-657-7311


Cushings- EMS and Hypothyroidism


What is the difference between these three potentially confusing conditions?

You've heard the words murmured like catchphrases in the tack room at the barn, by the farrier's truck, and even at Happy Hour amongst your horsey friends. You've always nodded your head in understanding, but after a while it all gets confusing. Once and for all, what is the difference between equine Cushing's disease, equine metabolic syndrome, and hypothyroidism?

Here we'll help make sense of these three conditions.

Pituitary Pars Intermedia Dysfunction (Cushing's Disease)

Commonly known as equine Cushing's disease, pituitary pars intermedia dysfunction (PPID) is a progressive syndrome affecting older horses. Common clinical signs include weight loss; a long, thick hair coat and delayed shedding; increased frequency of drinking/urination; and chronic laminitis (an inflammation of the laminae--the interlocking leaflike tissues attaching the hoof wall to the coffin bone). A loss of muscle mass along the horse's topline and sagging abdominal musculature can also cause the affected horse to develop a pot-bellied appearance.

The condition is thought to arise from age-related chronic oxidative stress (the production of oxygen free radicals that can damage many kinds of tissues), which leads to degeneration of the neurons that inhibit the pars intermedia portion of the pituitary gland (the endocrine gland at the base of the brain that stores and/or secretes many hormones important to body function). This causes the pars intermedia to increase in size (hyperplasia) and overproduce its derivatives, namely adrenocorticotropic hormone (ACTH, which regulates cortisol--the "stress hormone"--secretion). This overproduction causes the adrenal gland to secrete excess cortisol and leads to the horse drinking and urinating more, along with a predisposition to laminitis and, to some degree, insulin resistance (the body's inability to control glucose--or blood sugar--levels with normal amounts of the hormone insulin).

Veterinarians most commonly diagnose PPID in horses by measuring blood ACTH levels in the resting horse and by using the dexamethasone suppression test, whereby the veterinarian obtains a blood sample, gives an injection of dexamethasone, then measures the cortisol level in blood several hours later. This helps detect an ACTH increase or persistently high cortisol levels. However, clinical signs are sometimes more specific indicators of PPID than blood tests.

"Horses with chronic Cushing's disease can have decreased immune function," says Nora Nogradi, DVM, Dipl. ACVIM, a graduate student at Purdue University. "Therefore, we often check resting ACTH levels on our geriatric patients battling chronic infections (pneumonia, sinusitis, or periodontal disease, for example), to see whether underlying Cushing's disease plays a role. In these cases getting the endocrine disorder under control is essential for a successful recovery from the bacterial infection."

There is no cure for PPID, but it can be managed effectively with long-term administration of pergolide (available as a compounded drug only), which should cause the horse's clinical signs to diminish and diagnostic test results to improve within the first two months of use in 85% and 60% of horses, respectively.1

Equine Metabolic Syndrome

Equine metabolic syndrome (EMS) is a condition of obesity, insulin resistance, and laminitis in horses and, more commonly, ponies. It affects mainly younger horses and ponies from 5 to 15 years of age. Typically, affected horses are classic "easy keepers" (maintaining or gaining weight on a minimum amount of food) that are obese and/or have increased fat (adipose tissue) deposition in the neck (cresty necks), tailhead, and behind the shoulder. This is known as regional adiposity.

Both environmental and genetic factors are thought to contribute to EMS development. Overfeeding, insufficient exercise, and ponies' natural adaptation to survive on very little nutrition in the wild all contribute to obesity. Adipose tissue is associated with decreased insulin sensitivity. Scientists believe the resulting high levels of insulin (which the body produces to regulate circulating glucose levels) impair the digital blood vessels' ability to dilate and respond during times of challenge and, therefore, contribute to laminitis.

Three diagnostic criteria exist to identify a horse with this syndrome: obesity or regional adiposity, predisposition to laminitis, and insulin resistance. Veterinarians might diagnose insulin resistance through resting or dynamic blood tests of insulin levels, provided the horse is not under stress and has not ingested a high-carbohydrate meal recently.

Owners can manage horses with EMS through exercising them regularly (at least 30 minutes a day of riding or longeing) and changing their diets. "While regular exercise is key in managing horses with EMS to improve insulin sensitivity, most horses are diagnosed with this syndrome during an acute flare-up of laminitis," Nogradi explains. "In these cases it is recommended to adjust the diet, care for the feet, and resume the regular exercise regimen when the laminitis is under control."

Dietary modifications to manage EMS should include limiting or eliminating pasture access by using a grazing muzzle or confining a horse to a drylot; restricting/limiting hay intake to 1.5% of the horse's body weight; soaking the horse's hay for 30 minutes to decrease the starch content; and replacing grain with a commercial ration balancer. The latter should provide essential vitamins and minerals to supplement a forage diet without superfluous amounts of carbohydrates. Short-term L-thyroxine (synthetic thyroid hormone) supplementation can help initiate weight loss when necessary. Metformin and pioglitazone are insulin-sensitizing drugs that have been used to improve insulin resistance in humans, but they are still being researched as EMS treatment options.

Hypothyroidism

In years past, veterinarians attributed a syndrome of obesity-associated laminitis (now known as EMS) to hypothyroidism (decreased thyroid function) because ¬affected horses had low thyroid hormone levels in the blood, they responded to thyroid hormone supplementation, and clinical signs were similar to those of dogs with hypothyroidism.

One study has since shown that horses that have their thyroid gland removed do not develop laminitis, however, and another study indicates that the hormonal pathway between the pituitary gland and thyroid gland (pituitary-thyroid axis) was normal when veterinarians performed thyroid stimulation tests on horses with EMS. This means most adult horses do not have primary hypothyroidism (which is a disorder of the thyroid gland itself), but instead have a metabolic disturbance that has caused the pituitary gland to produce less thyroid-stimulating hormone. Treatment with phenylbutazone (Bute, such as for chronic laminitis in EMS) can also falsely decrease thyroid hormone levels.

Insulin resistance in EMS-affected horses does improve when horses are given a thyroid hormone supplement (e.g., L--thyroxine), but this is likely because of its use as a weight loss aid. Thus, this supplement should only be used as a short-term weight loss aid, as it might cause side effects when used long-term. These side effects include hyperthyroidism (thyroid overactivity) in horses with normal thyroid hormone levels prior to supplementation; secondary hypothyroidism when supplementation is discontinued suddenly; and owner reliance on the drug and, therefore, inappropriate EMS management.

According to Mary Durando, DVM, PhD, Dipl. ACVIM, of Equine Sports Medicine Consultants, in Newark, Dela., hypothyroidism is likely overdiagnosed when veterinarians detect low resting thyroid hormone levels, resulting in horses that "are placed on thyroid supplementation without a comprehensive (or accurate) diagnosis, even though they may have normal thyroid glands. Often the reason is vague poor performance, although thyroid disorders may have nothing to do with their performance problems."

True hypothyroidism in the adult horse is extremely rare and is seen more often in foals. Clinical signs include anemia (low red blood cell count); low body temperature, heart rate, and respiratory rate; lethargy; coarse hair coat; and obesity. Hypothyroidism in adult horses usually results from insufficient iodine intake and can be treated with thyroprotein or iodinated casein (a protein found in milk that is used as a binding agent). With treatment, these horses typically start showing improvement in two weeks.

Comparing the Conditions

So why are these three conditions often confused? It's easy to get early PPID and EMS mixed up because both diseases alter cortisol and insulin levels and, therefore, share signs of laminitis, infertility, and fat redistribution. Overlap can also occur as some EMS horses develop PPID over time. Equine metabolic syndrome and hypothyroidism might also be difficult to differentiate due to similar signs of obesity, low thyroid hormone levels, and positive response to L-thyroxine treatment. However, it is important to distinguish between PPID, EMS, and hypothyroidism since treatment for each condition differs greatly.

The best distinguishing factors between PPID and EMS are blood tests (typically measuring ACTH levels), age (average age of 19-21 years for PPID versus 5-15 years for EMS), and obesity (muscle-wasting and weight loss in PPID horses versus generalized or regional adiposity in EMS). Especially early in the disease process, the horse owner's astute observations can help distinguish the two conditions. According to Durando, an owner often "recognizes subtle changes earlier than the veterinarian, who only sees the horse once a year and may not be so familiar with it. In this way (the owner) can help to guide the vet as to early physical changes they may be seeing, and this may help pinpoint the problem earlier or add weight to equivocal lab tests."

Over time, as the disease progresses, PPID can be further distinguished from other conditions by the abnormal hair coat that most affected horses develop. Furthermore, insulin resistance is not a consistent finding in PPID-affected horses. True hypothyroidism is extremely rare in adult horses and can be distinguished from the other two conditions using a thyroid stimulation test.

Take-Home Message

Endocrine diseases of adult horses can be difficult to sort out. Nogradi emphasizes that "while in most cases the phenotype (physical characteristics) can be suggestive of the disease process, it is always recommended to seek veterinary assistance to achieve accurate diagnosis and initiate the appropriate management/treatment plan." Keep in mind the facts about PPID, EMS, and hypothyroidism so you will not only be well-armed during conversations at the barn but also be able to help your veterinarian arrive at an early diagnosis and develop a treatment plan for your horse. h


REFERENCES

1. Donaldson MT, LaMonte BH, Morresey P, Smith G, Beech J. Treatment with pergolide or cyproheptadine of pituitary pars intermedia dysfunction (equine Cushing's disease). J Vet Intern Med. 2002 Nov-Dec;16(6):742-6.