Managing Equine Leg Wounds with a Cast

Managing Equine Leg Wounds with a Cast

J.C. Thieke, DVM

Proud FleashFrom an anatomical standpoint, everything below a horse’s hock on their hind leg or the carpus (knee) of their front leg is just tendons, ligaments, joints, bone, and skin. As a result, there is less blood supplying nutrition to heal the wounds that occur on this part of a horse’s leg. The structures that are integral to a horse’s soundness, the joints, tendon, ligaments and bone, can become easily exposed with lower leg wounds. It is extremely important to manage these wounds effectively, so as to ensure optimal healing and minimal scaring.

After a horse has sustained a large wound to this area of their body, our first step is to evaluate which structures are involved and to what degree. If a joint is involved, that joint will need to be flushed and have antibiotics placed into it. If flexor tendons (on the back of the leg) are severed, they will need to be sutured back together. Other instances, if it is an extensor tendon (on the front of the leg) that is severed, it may be able to heal without the aid of sutures. Damage to the flexor tendons is much more serious than injury to the extensor tendons. In fact, significant damage to the flexor tendon can be career ending. In contrast, completely severed extensor tendons will heal and the horse can return to full athletic function in most cases.

Exposed or damaged bone will need to be scraped and debrided to expose healthy bone. If bone is exposed, the development of a dead piece of bone will occur. This is called a sequestrum. Usually taking 6 weeks to develop, it will need to be removed. Fortunately, most leg wounds do not develop this.

The assessment of the wound allows us to develop a plan to treat the wound as well as determine the likely prognosis for the horse. Most horse owners know lower leg wounds are susceptible to the development of exuberant granulation tissue, often called proud flesh. This development can be minimized if the tissues involved in the wound are immobilized during the healing process. One way to do this is with a good bandage, although a cast is preferable. The same fiberglass casts that are often applied to people can be used on horses. If the wound is below the fetlock, a short pastern cast that incorporates the foot can be used, and it can be applied while the horse is standing under sedation. If the wound involves the canon bone region, it will require a cast that incorporates the foot and extends up the leg to either the bottom of the carpus (knee) on a front leg or the hock on a hind leg. This cast can only be applied while the horse is under anesthesia.

Buttercup CastGeneral anesthesia is needed for any wounds that involve bones, joints, tendons or ligaments. These wounds usually require surgical debridement, joint flushes, or tendon repair. It is best if this is done with the horse anesthetized. In conjunction with these procedures, we often do a regional limb perfusion with antibiotics. This involves putting a tourniquet above the wound and placing a catheter into a vessel below the tourniquet for injecting the antibiotics. This allows us to get a very high concentration of antibiotics into the injured tissues.

Once the wound is cleaned, flushed, perfused, and sutured back together, it is time to apply the cast. The limb is padded well and held in the position desired for the casting. The horse is allowed to recover from anesthesia, then treated with antibiotics and anti-inflammatory medications based on the severity of the wound and the level of contamination present when the wound first occurred. Most horses will wear the cast for 4 to 6 weeks. The horse must be stall confined during this period and the cast is usually removed with the horse standing, unless the initial wound makes a second cast necessary.

The mobilization of the wound in a cast provides a better healing environment than that of a bandage. The cost of the cast itself over the course of the healing process is often cheaper than the bandage costs over the same amount of time, given the number of bandage changes that would occur over the same time frame. Typically, the wounds will also heal faster in a cast then in a bandage due to the amount of motion present at the wound site when it is bandaged. Cast treated wounds heal with a healthy flat granulation bed, rather than the raised proud flesh tissue that occurs with a bandage. The granulation bed will usually stay flat as the skin cells migrate across the wound to finish the healing.

Hypercementosis

Hypercementosis

Dr. Rick S. Marion

Hypercementosis PicHypercementosis is the name given to an emerging problem in older horses involving degeneration and eventual loss of incisor teeth in older horses. The incisor teeth are the 12 teeth that sit in the front of the horse’s mouth, seen when the lips are parted. They are used for biting and grabbing hay and grass but are not involved in the chewing, grinding or processing of feed stuff.  The incisors sit perpendicular to the jaw in young horses almost always become long and horizontal as the horse ages. The incisors can be severely affected by objectionable habits in the horse such as cribbing or raking on solid objects.

Hypercementosis, more properly and recently renamed Equine odontoclast 20131227_102524tooth resorption and hypercementosis (EOTRH) is a chronic degeneration of the roots of the incisors and canines. The degeneration of the root is accompanied by, or possibly caused by inflammation of the periodontal membranes, loosening of the tooth, bacterial overgrowth and gingivitis. The cause of the syndrome is not understood and it may in fact be various syndromes with many causes alone or in concert resulting in the same characteristic lesion.

The progression of the syndrome is inconsistent, but starts with the corner incisor or canine and progresses toward the center. As the root of the teeth are variably reabsorbed and hypertrophied, the periodontal membrane becomes inflamed and usually infected.  When the gingival tissue becomes infected, the tooth loosens. Loose inflamed teeth can be very painful but rarely will stop the horse from eating.

Treatments vary tremendously but, as of yet, no treatment has been found to stop the degeneration and eventual loss of the teeth. Antibiotics will at least partially control the infections in the gingiva and periodontal spaces. Anti-inflammatories, bute, banamine, aspirin and steroids may address the inflammation and therefore the pain. Splinting or braces may decrease the mobility of the teeth and address the pain from that angle. All treatments will eventually end with extraction of the teeth. The teeth may be extracted one or two at a time as the root fractures or infection makes removal necessary, or may be done on all incisors to address the issue of pain and treat the condition as aggressively as possible.

There are veterinarians who prefer to remove all the incisors at one time thinking that this aggressive approach is the fastest and most complete way to resolve the pain inflammation, and infection.  Even with all the incisors extracted horses can comfortably eat grass and hold food normally.

Equine Protozoal Myelitis (EPM)

By: Megan Slamka, DVM

What is Equine Protozoal Myelitis (EPM) and how can my horse get this?

EPM pic 1EPM is a neurologic disease characterized by ataxia or incoordination in horses caused by ingestion of the parasite Sarcocystis neurona.  Opossums shed S. neurona in their feces which may contaminate your horse’s environment.  If your horse subsequently ingests the organism, they may develop EPM. Horses under high amounts of stress or with other disease syndromes like Cushing’s, are at the most risk for developing clinical signs. Performance horses between the ages of 15 months and 4 years are more often affected. There is no known genetic predisposition and EPM appears less common during winter months. Opposums carry S. Neurona in their feces, horses ingest the parasite and it travels to their brain and spinal cord where it causes damage. 

What are the clinical signs?

Upon ingestion, S. neurona can migrate to the spinal cord and brain causing extensive EPM pic 2damage. The signs vary depending on which portion of the brain or spinal cord is affected. Horses are often bright and alert, but may appear uncoordinated or ataxic. Ataxia is the most common clinical sign. Other signs include muscle weakness, decrease in muscle mass and back soreness. The horse may have difficulty eating, a drooping lip, a head tilt or dribbling of urine all related to further nerve damage.

How is EPM diagnosed and how can we treat it?

Diagnosis of EPM can be difficult, due to ataxia being mistaken as lameness or a spinal injury. Your veterinarian will take a thorough history and rule out such things as trauma, nutritional deficits, toxicities or other infectious causes of neurologic disease. There are many blood tests to detect EPM that detect antibodies to the parasite. One of the most recommended diagnostic test is the Immunofluorescent Antibody test (IFA) on cerebrospinal fluid. The IFA is the most sensitive and specific test for S. neurona. This means you can better trust the test results are accurately telling you your horse is positive or negative. Cerbrospinal fluid is collected by performing a spinal tap.

Treatment is aimed at providing nursing care as well as using antiprotozoals to treat the infection. Severely effected horses may need to be put in a sling. They may need protective gear and nutritional modifications as well as deep bedding. There are several different treatments available, and the option that your veterinarian chooses will be based on the symptoms that your horse is showing.

What is the prognosis? and How can we prevent it?

Most horse’s neurological deficits improve. However, full recovery occurs in less than 25% of affected horses. Improvement is often observed within the first week of therapy and increases steadily. Performance animals should stay out of training while undergoing therapy. Unfortunately, chronic signs such as muscle atrophy rarely ever improve.

As with most life threatening disease, prevention is key.

Preventative measures include:

  • Cover feed in storage bins
  • Don’t leave grain uncovered for opossums to get into
  • Elevate hay off the ground to prevent contamination from feces on the ground
  • Minimize stressful scenarios such as long trailer rides that may make your horse more susceptible
  • Use good standards of hygiene such as regular cleaning of hay and water troughs

Summary

  • EPM is a parasitic disease that causes neurologic signs such as ataxia in horses.
  • Horses become infected by ingesting the parasite which is transmitted by opossum feces.
  • Treatment includes Ponazuril for 28 days along with supportive care to prevent self injury.
  • Prognosis is good for survival, but poor for full return to previous level of performance.
  • Prevention involves minimizing overtly stressful scenarios that may make your horse more susceptible and minimizing contact with opossum feces.

Equine Dental Extraction

By Megan Slamka, DVM

Introduction

6a00d834529d8769e20120a8bb0e23970bRoutine dental exams are a vital part of general horse health. Dental examinations can reveal very common oral pathologies such as diseased, fractured, loose and retained deciduous teeth (caps) that need to be removed.  Failure to remove these teeth can lead to more than discomfort for the horse, but serious infection as well. This handout will describe the indications, procedures, and potential complications for extracting equine teeth.

Indication

Horses of all ages may require dental extraction. Extraction can be done under general anesthesia via repulsion of the tooth or standing with heavy sedation. Recently, standing extractions have become more popular with veterinarians and owners for its advantage of not having to undergo general anesthesia, as well as minimizing damage to associated bony structures. That said consideration of the horses age, temperament, tooth location, amount and condition of exposed crown must be taken into account. As horses age, their teeth continuously erupt therefore the amount of reserve crown (amount of tooth below the gum line) becomes less and less. Therefore, younger horses with extensive amounts of reserve crown make extraction difficult.

Procedure

Prior to extraction of the problem tooth, dental radiographs should be taken to verify the extent of pathology, as well as, to identify if associated structures such as adjacent teeth or sinuses are affected.

The procedure as mentioned above, can be carried out under general anesthesia or standing with heavy sedation. We will discuss the procedure for standing extraction, as this is the most common option for uncomplicated cases.

After a thorough oral exam and radiographic exam, the process of extracting the tooth can begin with appropriate sedation on board.

Local anesthetics are used to minimize pain, as well as injectable drugs that provide both pain relief and sedation.

The horses head is elevated and suspended with either a dental halter or headstand with the mouth held open with a dental speculum. Due to the duration of this procedure horses are given breaks every 30-45 minutes.  For cheek teeth; the gum is detached from underlying alveolar bone with a dental pick.  Placement of molar separators at the front and back of the tooth in the interdental space are used to loosen the periodontal ligament1. The molar separator is held in placed for 1-3 minutes and then moved to the opposite side of the tooth.  After applying the molar separator, a molar forceps is placed as in figures 1 and 2. The molar forceps are used to wiggle the tooth from side to side with slow and steady pressure on the tooth. Care is taken to not fracture the tooth roots or adjacent teeth. As the tooth loosens, a squeaking sound can be heard.  When the tooth is sufficiently loosened, extraction can be attempted. The tooth is extracted using the molar forceps and a fulcrum as seen in figure 2. After extraction, the alveolar pocket is packed with dental impression material.

Tooth Ext pic 1
Picture shows placement and movement (medial to lateral) of the molar forceps
Tooth ext pic 2
Molar fulcrum placement and tooth extraction

Incisors are removed in a similar manner whereby an incision is made on either side of the tooth and along the gingival margin. The alveolar bone at the front of the tooth (labial surface) is removed down to the level of the reserve crown. A small periodontal elevator or osteotome is used to loosen the tooth and the tooth is removed with forceps . Incisor extractions are closed with suture that is removed in 10-14 days unless the suture falls out, which is a common occurrence.

Follow-up Care

Food and water should be withheld for 4 hours post extraction. For cheek teeth, the extraction site should be inspected and lavaged with warm water daily if possible.  Non Steroidal Anti Inflammatories (NSAIDs) such as Bute or Banamine will be used pre and post operatively to alleviate pain and inflammation. Finally, a broad spectrum antibiotic may be used to minimize potential for infection to develop.

Potential Complications

Post operative complications are rare. However, potential complications include secondary sinusitis with infected maxillary cheek teeth (08-11), sequestration (infection of bone), loosening or damage of adjacent teeth, hemorrhage and myalgia of masticatory muscles. Figure 3 shows the location of a maxillary cheek tooth in relation to the sinus. If sinusitis is present or develops, a hole (trephine) will be placed in the sinus to lavage the sinus twice daily.  Frequent dental equilibration (floating) is necessary to avoid development of a step or wave mouth.

Overall, prognosis for horses requiring tooth extraction is good to excellent with consideration and planning of the extraction procedure and post-operative care.

Signs of oral pain in your horse

• Problems with biting; head shaking, gaping at the mouth and overall discomfort when the bit is placed in the mouth.

• Quiding (dropping feed when eating)

• Increased salivation

• Facial/Mandibular swelling

• Malodorous nasal discharge; can be unilateral or bilateral and may indicate a sinusitis secondary to dental disease or fracture