HORSE HEALTH INFORMATION

Information about caring for your horse.

Potomac Horse Fever

We have been seeing more cases of Potomac Horse Fever (PHF) this august likely due to the wet and humid June and July we have had this year. Because of this, we wanted to provide all of you with some information about this challenging disease.

- PHF is caused by the bacterium Neorickettsia risticii which normally infects fresh water insects like snails, trematodes, and the larval stages of mayflies and caddisflies.

- Horses most likely get infected by drinking water containing this insects from ponds, drainage ditches, and streams. Additionally, when the adult mayflies or caddisflies emerge, they fly around barns and then can be ingested by the horse when they die in feed or water sources.

- Signs of PHF include high fevers, depression, colic, diarrhea, and laminitis.

- Treatment includes the antibiotic oxytetracycline, banamine, and fluids for severely dehydrated horses. Biosponge is used to help with diarrhea. Severely affected horses may require hospitalization.

- The mortality rate of PHF is typically about 10% and prognosis worsens if the horse develops severe diarrhea or laminitis.

- There are vaccines available but these are not highly effective. Vaccinated horses can still develop the disease. Horses that have survived infection with PHF retain immunity from the disease for up to 2 years.

- Prevention includes limiting your horses' access to natural water sources, turning off lights near barns at duck (when mayflies swarm), and carefully checking hay and water sources when you have notices mayflies or caddisflies around your property.

If you notice your horse is depressed, off feed, has a fever (temp above 101.5 F) or has loose manure, call us immediately.

IRAP: A New Treatment for Degenerative Joint Disease

Osteoarthritis, also called degenerative joint disease (DJD) is one of the major causes of lameness in horses. Some of the most affected joints are the hock, fetlock, stifles and coffin joints. Typically, we recommend therapy including rest, anti-inflammatory drugs (Bute and Banamine), Adequan, and joint injections consisting of steroids and hyaluronic acid. Recently, however, a new therapy became available called Interleukin-1 Receptor Antagonist Protein or IRAP.  We are pleased that we can now offer this therapy to our clients.  Here's how it works: interleukin-1 (IL-1) is a protein produced in the joints as a result of the inflammation from the degenerative joint disease. As IL-1 increases, the amount and severity of damage to joint cartilage worsens the DJD process.  IRAP is a protein derived from your horse's own blood that can be injected back into the joint to counteract IL-1. The IRAP procedure involves drawing blood from your horse and then incubated in a special syringe to promote the production of the IRAP protein. While in the special syringe, the blood is centrifuged to separate the plasma (containing IRAP) from the blood cells. This plasma can then be injected into the joint(s) on an appropriate treatment schedule.

Initial studies indicate that IRAP therapy has been improving lameness and joint swelling in horses with signs of DJD. It is important to note that IRAP can not reverse permanent damage, but may help decrease inflammation and slow progression of DJD. IRAP can be used in combination with other joint therapies.  

Equine Gastric Ulcer Syndrome

Gastric ulcers in horses are probably more common than you think. Studies have shown a prevalence of 25-50% in foals and a frequency of up to 40% in general adult horse population and up to 90% prevalence in performance horse populations. Ulcers in foals are a sightly different issue so this note will focus on adult stomach ulcers.
 
So why do horses get stomach ulcers?  The horse stomach continuously secretes variable amounts of hydrochloric acid throughout the day and night and secretion of acid occurs without the presence of feed material. Horses are designed to be eating forage material (hay or grass) 18-20 hours of the day. We can contribute to ulcer problems when we limit the horse to meal feedings. Additionally, diets high in carbohydrates such as grain meals lead to increased volatile fatty acid production in the stomach. These volatile fatty acids increase stomach lining damage. Ulcers in the squamous mucosa of the stomach are primarily due to prolonged exposure to hydrochloric acid, pepsin, and bile acids. Ulcers occurring in this region are similar to Gastroesophageal Reflux Disease Syndrome (GERDS) in humans.

Chronic or high dosage use of products like Bute and Banamine can also lead to stomach ulcer formation (which is why you should only use these products under veterinary guidance). This type of medication blocks prostaglandin synthesis. Prostaglandins help buffer and protect the stomach lining. Blocking prostaglandin synthesis causes deceased mucosal blood flow, stimulates gastric acid secretion, and inhibits bicarbonate secretion by the glandular mucosa.
 
How do I know if my horse has stomach ulcers?  The signs of stomach ulcers can be very obvious or very subtle depending on the individual horse and the severity. Signs include: poor appetite or starting and stopping eating, low grade colic, change in behavior or attitude to depression or "grumpiness," excessive salivation, teeth grinding, weight loss, decreased performance, etc. Stomach ulcers can be seen by passing an endoscope into the stomach via the nose.
 
How do we treat stomach ulcers?  Currently, there is only one FDA approved treatment for gastric ulcers in horses, GastroGard (Omeprazole paste, Merial Limited, Atlanta, GA). GastroGard is a paste and is given to horses once daily for 28 days to treat EGUS. It is also labeled for prevention of recurrence of gastric ulcers at ½ dose. The medication contained in GastroGard is the same medication found in the “Purple Pill” Prilosec that is currently sold to humans for treatment of gastric ulcers. Additionally, studies have found that using alfalfa as the forage component of the diet helps decrease acid production and buffer the stomach. Changing the horse's stressors and diet can really help with gastric ulcer syndrome. Limiting grain meals, increasing pasture time or outside time, and maintaining a regular schedule can really help.
 
If you think your horse may suffer from Equine Gastric Ulcers, please feel free to call us to discuss your options.
 
(www.aaep.org provided information for this note)

COLIC

What does Colic mean?

The definition of colic is; pain caused by a problem with an abdominal organ.  This can be pain from any part of their digestive tract, liver, kidney, or reproductive organs.  However, the majority of colic cases are due to disturbances of the gastro-intestinal tract.

What is the horse’s Gastro-Intestinal Tract?

The horse’s GI tract consists of the stomach, small intestine, cecum, colon, and small colon.

1.The stomach in the horse can comfortably hold 2-3 gallons and is basically a mixing station for food before it is passed on to the small intestine.  The size of the horse’s stomach is relatively small considering the size of the rest of the GI Tract.  Food and liquid generally are only in the stomach for around 10-20 minutes.

2. The small intestine is roughly around 80 feet long and this is where the majority of the digestion and absorption of nutrients from their grain occurs.  This is a fairly rapid transit system sending food along at approximately 1 foot per minute.

3.The cecum is a large wine-flask-shaped organ capable of holding anywhere from 5-7 gallons of fluid and plant material.  This is a fermentation chamber where a significant amount of water is re-absorbed back into the body and where the breakdown of plant material is initiated.

4. The large colon is around 10-14 feet in length and is basically free floating in the belly.  It generally will contain around 20-25 gallons of water and food material.  This is where the rest of the water is re-absorption and continued digestion of plant material takes place.

5. The small colon is another 10-12 feet in length and is the last part of the system where the rest of the water is re-absorbed and the feces are formed.

The horse is basically designed to eat small amounts of food over a long period of time.

What causes colic?

There are many different causes of colic, but the bottom line is that when horses colic there is a disturbance in one of the five regions of the GI tract.  This can be due to impaction, gas, entrapped or twisted small intestine, displacement or twist of the colon, parasites, ulcers, poor teeth care, over-eating/over-feeding of grain, ovulation, etc.

What are the signs of colic?

A horse can exhibit many different signs but they are all a reflection of the fact that they have abdominal pain.  They may show any combination of the following signs: biting at sides, pawing, lying down, rolling, not eating, stretching to urinate but no urination occurs, looking at belly, kicking at their belly, sweating, and trembling.

When to call the vet?

If you have any questions it is always better to give me a call and let me know what is happening and then we can make a judgment as to what to do next. The important thing to determine with colic is whether the colic is a surgical case or a medical case.  A surgical case is a physical problem that can only be repaired by surgical manipulation.  A medical colic is treated with just drugs and fluids.

Surgery Prognosis:

1. For large colon colic the surgical success rate is in between 80-90%.

2. For small intestine colic the success rate will be more in the 45-60% range.

How to Prevent Colic:

There is no tried and true method to preventing colic but there are some practices you can follow.

1. Try to keep their daily routine consistent and try not to make any sudden feed changes.

2. Feed good quality hay.

3. If feeding grain, try to feed 2-3 times throughout day instead of one big meal.

4. Provide plenty of clean, fresh water (careful of ice in the winter!!).

5. Provide good maintenance care with worming and teeth programs.

6. Be closely observant to changes in their behavior or stall habits.

Unfortunately, colic cannot be 100% prevented; early diagnosis and treatment will provide your best results from either medical or surgical colic.

*It is helpful to you the owner, to me the veterinarian, and most importantly the horse, to decide ahead of time if surgery is an option.  The quicker a horse is operated on the much better the prognosis. *

Pastern Dermatitis, aka "Scratches", "Mud fever," "Greasy heel"

Pastern dermatitis is the name for a skin reaction that can have a variety of causes. Most commonly the area affected is the back of the pasterns and heels but sometimes the inflammation can extend up the entire lower limb. White-haired areas seems to be more commonly affected than dark-haired areas. The appearance is of scabby oozing lesions on the skin, sometimes forming thick crusts. The skin when cleaned off has the bright pink appearance of inflammation and sometimes has ulcerated areas. In chronic cases the skin can become thickened and plaque-like.  This condition is very painful for the horse, and can cause lameness in some cases.

Causes for pastern dermatitis include bacterial infection, contact with caustic substances, fungal infection, mites and photosensitization related to pasture plant toxicity. Chronically wet skin and hair from environmental moisture (such as tall wet grass in a pasture) can weaken the skin's defenses and lead to the infection that causes scratches. Some horses can have an immune-mediated condition that causes pastern dermatitis.

Treatment for pastern dermatitis includes the following:

- Clipping the hair from the affected area to allow easy access to the skin and to help keep the area dry.

- Gently cleaning the skin with warm water and antibacterial scrubs such as Betadine or Chlorhexadine. After softening the scabs and crusts with the wash, they are gently removed. This can be quite painful and may require sedation of the horse.

- The leg is dried after each cleaning and then topical medications are applied. We like to use Animax ointment which provides antibacterial, antifungal, and anti-inflammatory activity.

In some cases we wrap the legs initially to keep them clean and dry or may put the horse on an injectable antibiotic as well. Many horses are also put on Bute or Banamine to help with pain.

Some horses suffer from recurrent episodes of pastern dermatitis. In these cases we try to determine an underlying cause by looking at the environment (is the horse in a chronically wet or muddy area) and perhaps doing a biopsy of the skin. If your horse suffers from recurrent or severe scratches, please be sure to call us so we can help!