Classic Horse

Ann Chapman, DVM, Dipl. ACVIM

Equine Medicine Fellow

Equine Health Studies Program

Louisiana State University

School of Veterinary Medicine

Baton Rouge, LA

www.LSUEquine.com

(225)-578-9500

Strangles is a highly contagious disease of the upper respiratory tract caused by the bacteria Streptococcus equi.  It can be a very frustrating and persistent disease for horse owners worldwide.  This organism invades the lymph nodes and respiratory tissues of the head and neck.  The early clinical signs of the disease are fever, nasal discharge and lymph node swelling.  Initially the nasal discharge may be clear, but as the disease progresses, it becomes thick and tenacious.  The lymph nodes below the jaw and neck become enlarged, hot and painful.  As these lymph nodes abscess, they may begin to ooze and eventually rupture and drain externally or internally.  Internal lymph nodes may drain into the guttural pouches of the head leading to pus accumulation.   Chronic infection of the guttural pouches can lead to drying of the pus and formation of solid, concretions called chondroids.   In complicated cases of Strangles, the lymph node swelling may exert pressure on the esophagus and pharynx, which results in difficulty swallowing.  If the lymph node swelling obstructs the airway, the horse will develop respiratory difficulty and require emergency attention, hence the origin of the term “strangles”.   Any horse lacking sufficient immunity to the organism is vulnerable, however the very young (1 to 5 years of age) and very old are predominantly susceptible.

Deaths attributed to Streptococcus equi are rare; however the disease can rapidly spread from horse-to-horse resulting in a local outbreak.  The bacteria can be transmitted from contaminated buckets, feeding utensils, grooming tools, tack and other equipment. In addition, feed, water and even human hands are capable of transmitting the bacteria to a naïve horse.   The organism does not persist long-term in the environment; however stalls or trailers that were recently contaminated with infected nasal discharge may be source of infection to other horses.   In many cases, the introduction of strangles to a farm can be traced to travel of one or more horses, or arrival of asymptomatic carrier horses.

A diagnosis of strangles is usually made when the horse exhibits the classic clinical signs of fever, lymph node swelling or drainage and purulent nasal discharge.   To confirm the diagnosis, a sample of the nasal discharge from either a swab or a nasal washing, or pus from a draining lymph node can be sent to laboratory for bacterial culture.   However, early in the disease process, before Streptococcus equi has emerged into the nasal passages, the culture may be negative. Equally challenging is the diagnosis of the carrier state, which may require three sequential samples using specialized equipment (long swabs or endoscope) to sample the nasopharynx or guttural pouches. Polymerase chain reaction (PCR) is a newer test that has recently been developed to detect very small quantities of Streptococcus equi DNA. Unfortunately, this test detects both live and dead bacteria, so its usefulness may be limited to detecting asymptomatic carrier horses and determining when the infection has been eliminated from a recovering horse.

Treatment for strangles depends on the stage and severity of the diseased individuals.  Many veterinarians argue whether or not to use antibiotics in the treatment of strangles.  All agree however, that any affected horse should be quickly isolated and maintained separate from the remaining herd.

Horses with early clinical signs of fever and depression, may be placed on antibiotics as an initial means of controlling an outbreak by arresting the bacteria and preventing abscess formation.  However, most veterinarians do not advocate antibiotics in mild clinical cases, since it may inhibit the development of protective immunity to the bacteria.  Once a horse develops lymph node abscessation, hot packs and poultices are applied to aid in maturation and drainage.  In some cases the abscess will require lancing if spontaneous drainage does not occur.  Once open, the abscesses are often flushed with antiseptic solutions to promote healing.  Anti-inflammatory medications, such as phenylbutazone or flunixin meglumine, may be helpful to control the pain and swelling which promotes eating and drinking.

Antibiotics should be avoided unless the infection has been longstanding or the horse has advanced signs of the disease.  These include obstruction of the upper airway by enlarged lymph nodes, pneumonia or abscesses in other body organs (such as liver, kidney, brain, spleen, lung or intestinal tract).   If antibiotic therapy is administered, it should be continued until complete resolution of the disease, since clinical signs may return if the antibiotics are stopped prematurely.  When the infection extends into the guttural pouches it must be treated with flushing through a specialized catheter, an endoscope or through a surgical incision.

To reduce the introduction of strangles to a farm, various strategies are recommended.  New arrivals should be held in quarantine for 2-3 weeks prior to mingling with other horses on the farm.  While in quarantine, a rectal temperature should be taken daily and the horse observed for cough or nasal discharge.  Personnel handling these horses should wash their hands and use alcohol-based hand cleansers when they are finished dealing with the animals.

When a strangles outbreak occurs, all the horses with signs of strangles and the horses who have been in contact with them, should be immediately quarantined. Symptomatic horses should be managed appropriately and exposed horses should be monitored as mentioned previously.  Individuals handling these horses should use latex gloves and manage these animals after handling non-exposed horses on the farm.  Buckets, feeder and other equipment should be disinfected daily with dilute bleach or other disinfectant if available (quaternary ammonium or phenols).  Bedding should be composted separately or removed from the premises and the stalls walls and flooring disinfected daily.  Effective fly control should be implemented to help spread the disease to unaffected horses.

Vaccination for the control of strangles is a source of controversy since a solid immunity to the disease is usually not attainable, and there are potential complications with vaccine use.  There are two types of products available: extract vaccines and a live vaccine.  Extract vaccines contain the components of the S. equi organism and are given intramuscularly. The most common side effect of this vaccine is pain, swelling or abscess at the sight of injection.  The live vaccine is composed of a non-infectious strain of S. equi and is given intranasally.  Side effects of this vaccine are infrequent, but can include lymph node swelling or abscessation especially if concurrent injections are being administered.  The development of immune response with vaccination takes 7 to 10 days, so during an outbreak only those horses without contact of affected horses should be vaccinated.  Horses with current signs of strangles or that have recovered from a previous strangles infection should not be vaccinated.   An uncommon but serious adverse reaction that can occur with vaccination (or more commonly with natural infection) is a vasculitis called purpura hemorrhagica.  However, as researchers continue to study S. equi, newer and safer vaccines are on the horizon.

In conclusion, strangles is a common and sometimes very serious contagious disease of horses.  However, with careful vigilance, preventative measures and early recognition, it is a disease that can be managed and controlled.

Brandy Darby; Piper Lambert; Daniel J. Burba, DVM

Equine Health Studies Program

School of Veterinary Medicine

Louisiana State University

Baton Rouge, LA  70803

www.LSUEquine.com

Introduction

Septic arthritis, commonly referred to as joint ill in foals, is a very serious and potentially life-threatening bacterial infection of a joint and/or the surrounding bone.  Although it can be seen in any age horse, in almost any joint, it is seen far more often in young foals and usually in distal joints such as the hock, stifle, fetlock or carpus.  Due to the extremely serious nature of these infections, being able to recognize it and begin early treatment is key to having a chance for a successful outcome.

Which Horses Are At Risk?

Young foals are at greatest risk and several factors have been identified that predispose them to developing septic arthritis. The most important of these is inadequate ingestion of colostrum (the first milk produced by the mare after foaling that contains antibodies needed in order for the foal to be able to fight off infection).  The foal may not have received adequate colostrum for a variety of reasons, such as:

• A delay in suckling, either because the foal was unable to get up often enough to nurse or because of a problem with the mare that prevented her from being with her foal during the first 24 hours.  Colostrum consumed after the first 24 hours of the foal’s life is of little, if any benefit.
• The mare leaking colostrum before foaling
• The mare not being adequately vaccinated during pregnancy for infectious diseases in the region.

Other risk factors for foals include concurrent disease processes, such as pneumonia, diarrhea or septicemia (bacterial infection of the bloodstream), those kept in unclean conditions or those who have suffered some type of trauma.

Although the disease is far more common in foals than in adult horses, it should not be forgotten that septic arthritis can be seen in any age horse.  Risk factors for adult horses differ slightly from those for foals.  As always, injury will predispose to infection, but horses that receive joint injections or have recently undergone surgery of a joint are also considered at risk.

How Septic Arthritis Develops

There are two ways that bacteria may enter a joint.  Usually in foals, bacteria travel in the bloodstream from a site of infection elsewhere in the body.  The bacteria become lodged in the blood vessels near joints because these vessels are small and blood flow is slow through them.  Bacteria may also enter secondary to trauma or medical treatment (such as joint injections or surgery) that exposes the joint to the outside environment.

Once an infection is established, the body mounts an inflammatory response against the bacteria present.  White blood cells and the synovial membrane (the inner lining of the joint), release degrading enzymes, intended to destroy the bacteria, but they also cause considerable damage to the cartilage of the joint in the process.  If the damage to the cartilage is extensive enough, osteoarthritis (also known as degenerative joint disease) may develop.  Once the joint has been this badly damaged, the chances of that horse having a successful athletic career later in life are greatly decreased.

When To Call Your Veterinarian

Any foals at risk for developing septic arthritis should be monitored closely.  The first sign that there may be a problem is that the foal appears “not quite right”.  Signs to look for include spending more time lying down, lameness, swelling, heat or pain around the affected joint(s).  It may be easy to ignore these signs and assume that the mare may have stepped on the foal. Thus treatment may be delayed which may seriously decrease that foal’s chance of survival.  All lame neonatal foals should be assumed to have septic arthritis until otherwise proven.  You need to call your veterinarian immediately as this is a true emergency!

When the veterinarian examines the foal, he or she will ask you a series of questions so that they can get an understanding of the patient’s history and perform a thorough physical examination.  Arthrocentesis (placing a needle into a joint in order to collect a sample of joint fluid) will be performed on all suspect joints in order to confirm a diagnosis of septic arthritis.  Fluid collected will be submitted to a laboratory for analysis.  Typically, septic joints will have many more white blood cells present than a normal joint and the majority will be neutrophils, the white blood cells primarily responsible for fighting bacterial infections.  In addition, the protein content will be increased and in advanced cases, the fluid will lose its characteristic “stringy” quality.

The fluid collected will also be cultured to determine the type of bacteria is causing the infection as well as what antibiotics the bacteria are susceptible to.  The culture and antibiotic susceptibility testing results may take a few days to get back from the laboratory. Thus, the foal will be started immediately on a broad-spectrum antibiotic regimen. When the results are obtained, your veterinarian may decide to change the antibiotic(s) being used if another antibiotic regimen will be more effective or continue the current antibiotic course, if appropriate, until it is completed.

Radiographs (x-rays) will also often be taken when the veterinarian first sees the foal to assess for joint damage, involvement of the surrounding bone or other potential problems that need to be addressed, such as fractures.  Some of the bony changes may not be evident on this first set of x-rays.  Follow-up radiographs will need to be taken every few days to couple of weeks to determine the extent of the damage and monitor resolution or progression of the infection.

The Road to Recovery

Once your veterinarian has established a diagnosis of septic arthritis and assessed the damage sustained by the joint, then the real work can begin.  Unfortunately, treatment is often quite expensive and labor and time intensive.  The future quality of life of the horse will always need to be considered before investing the time and money needed to get these horses through the infection.  In addition to antibiotic therapy, affected joints will have to be lavaged with large volumes of sterile fluids in an attempt to decrease the number of bacteria and the amount of inflammatory debris present.  This needs to be performed under sterile conditions with either sedation or general anesthesia every few days until the infection is under control.  In some cases, joint lavage may not be sufficient, and more advanced surgical procedures, including arthroscopy (evaluate joint and remove debris using a scope) or arthrotomy (surgically open the joint) will be required to clean out the joint.  Other important aspects of treatment include pain management and preservation of the remaining cartilage in the joint with substances such as hyaluronic acid or polysulfated glycosaminoglycans. Joint physiotherapy in the form of passive range of motion exercises, controlled exercise and or swimming can be useful once the acute stages of inflammation have subsided. This helps keep the joint flexibility and prevents adhesions from forming within the joint and helps prevent the joint capsules from becoming restrictive due to fibrosis and scarring.

If a horse makes it through the acute infection, it will have to be rested for a prolonged period (up to six months) in order to allow the joint to heal properly and prevent further injury or pain.  The development of degenerative joint disease after infection is the major long-term concern and will be the limiting factor in the future athletic potential of the horse.  The prognosis with septic arthritis is always guarded and depends on a number of factors such as the number of joints involved, whether or not bone is involved, the duration prior to detection and treatment, the type of bacteria and their antibiotic resistance pattern, but with early detection and aggressive therapy, the infection can be resolved, the joint function preserved and the horse resume an athletic activity.

Charles T. McCauley, DVM, Diplomate ABVP and ACVS

Assistant Professor, Equine Surgery

Equine Health Studies Program, School of Veterinary Medicine

Louisiana State University, Baton Rouge, LA  70803

(225)-578-9500        LSUEquine.com

Introduction

Domestication has significantly improved the quality of life and prolonged the average life expectancy of horses. Improved nutrition, housing, preventive health care and parasite control programs have resulted in a large population of geriatric horses, sometimes living into their thirties and forties. Highly processed grain diets, confinement, minimal exposure to continuous grazing, feeding from elevated troughs, and minimizing exposure to environmental abrasive substances have as a consequence affected the way in which the horse’s teeth erupt and wear. With the increasing age of the horse population, comprehensive dental care is becoming more important. Up to 10% of equine veterinary practice time in the US involves dental related conditions. Horse’s teeth are long and primarily composed of reserve crown that is buried deep below the gum line (gingiva) within the upper (maxilla) and lower (mandible) bones of the jaw. Unlike humans, the crown erupts continuously as the horse ages until it is exhausted and only shallow roots remain to hold the tooth in the bone. Throughout the horse’s lifetime, the continuously erupting crown of each tooth is worn away at a rate of 2 – 4 mm per year by the opposing tooth. Once the reserve crown is exhausted, the horse is unable to chew properly and as it has been said, “horses do not die of old age, they simply run out of teeth”.

Although we associate dental disease with obvious clinical signs, more often than not dental problems develop slowly without outward symptoms. Frequently there are no obvious external signs until the disease has progressed to complications such as infection of the gingiva, tooth roots, bone or sinus. When signs of dental disease are present it may be manifested by any of the following signs:

• Quidding – dropping partially chewed, saliva soaked food
• Halitosis – bad breath
• Weight loss, poor body condition, or failure to gain weight
• Head shaking, bitting problems, resistance to the bit, and abnormal head carriage
• Excessive salivation
• Reluctant or slow eating or chewing
• Food pouching
• Oral pain
• Changes in fecal consistency – ranging form dry hard fecal balls to diarrhea and often comprised of undigested long fibrous material
• Other behavioral/training issues

Many times poor dentition is mistaken for behavioral or training problems that appear not to be correctable. Lack of appropriate dental care can lead to early attrition and tooth loss, making it difficult for older horses to maintain their body weight and can also lead to systemic manifestations of dental disease such as choke (esophageal obstruction) or colic.

Dental Anatomy

                   Adult horses have 36 to 44 permanent teeth. These teeth include 6 upper and 6 lower incisors. There are normally 3 or 4 premolars and 3 molar teeth in the upper and lower jaw, which are collectively known as the cheek teeth.  The first premolars, if present, are usually poorly developed or vestigial and are termed “wolf teeth”. These teeth are frequently removed by veterinarians due to the perception that failure to remove wolf teeth will result in problems with the bit. The remaining premolars and molars are used primarily for grinding the fibrous feed material typical of the horse’s diet. It is important to remember that the upper jaw is wider than the lower jaw. To accommodate this, the occlusive or grinding surface of the cheek teeth is slanted approximately 15-degrees.

Dental Examination

The only way to accurately identify abnormalities in the dentition of a horse is by complete and thorough oral and dental examinations. A proper dental examination is performed with the horse adequately restrained in a stock and usually sedated. The dental examination typically begins with a discussion of any history of abnormal behaviors. This may give clues to an existing problem that needs to be addressed. In addition, it is important for the person performing the examination to have an understanding of the horse’s use. The number, position and alignment of the incisors are evaluated first. Supernumerary (too many) incisors and fracture or missing incisors are not uncommon and should be noted. Malocclusion of cheek teeth such as hooks or steps can prohibit normal front-to-back and side-to-side movement during eating and chewing. Side-to-side movement or lateral excursion of the lower jaw in relation to the upper jaw is necessary for the normal chewing and grinding motion of the horse and should be evaluated. While the upper jaw is held in a fixed position, the lower jaw is moved laterally. A normal lateral excursion is roughly the width of 1½ teeth. In addition, due to the normal angle of the cheek teeth, as lateral movement continues and the grinding surfaces of the cheek teeth come into contact, the incisors should separate approximately 2 – 6 mm.  Also necessary for normal chewing, the incisors must be flat and level from one side to the other. Locking of the jaw, decreased lateral excursion and failure of the incisors to separate are all indication of abnormalities of the cheek teeth.

Examination of the cheek teeth is facilitated by use of a full mouth speculum, dental mirror and bright light source. This should include examination of the soft tissues including the inside of the cheek and tongue for the presence of ulcerations, lacerations or erosions. Each cheek tooth in both the upper and lower dental arcades should be examined for evidence of abnormal location, presence of sharp enamel points and abnormal overgrowths, fractures, spaces between the teeth (diastema) and areas of decay. Suspicious areas should be further investigated using a dental probe and the tooth should be assessed for looseness.

Dental Abnormalities

Foals, Juveniles and Young Adults

It is a misconception that young horses do not need regularly scheduled dental examination and care. Sharp enamel points begin to develop almost immediately after eruption of the cheek teeth. At a minimum, foals should be examined at birth and again at weaning for evidence of congenital abnormalities such as overbite or parrot mouth and developmental abnormalities such as poor incisor alignment and errant cheek tooth eruption. Tumors of dental origin and those affecting the bones of the jaw are also commonly diagnosed at this age. Eruption of the permanent teeth begins at approximately 1 year of age and continues until the horse is 4 – 5 years old. As the premolars erupt, they cause resorption of the deciduous root and push the remaining deciduous crown up above the gum line. This premolar cap is usually lost shortly after the molar tooth erupts through the gum. In some instances, this cap can be retained and have sharp spicules of enamel that may penetrate the gum when pressure is applied by the opposing premolar resulting in pain. Affected horses are often presented to veterinarians for examination due to excessive dropping of feed or behavioral problems. Removal of retained caps results in almost immediate resolution of oral pain. In addition to retained premolar caps, asynchronous eruption of premolar and molar teeth can result in malocclusions that can affect the horse’s ability to adequately grind feed. This problem is easily recognized and corrected on a routine oral examination. Finally, there is evidence to suggest the enamel of horses up to 6 – 7 years of age is softer than that of older horses. Because of this, sharp enamel points may reform earlier after routine dental care in young horses. For these reasons, it is recommended that young horses form birth to 7 years of age undergo a dental examination approximately every 6 months.

Adult Horses

Mature horses between the ages of 7 – 15 years of age with normal dentition typically require only annual examinations and routine care. The most common abnormality observed in this group of horses is the development of sharp enamel points on the outer surface of the upper check teeth and the inner surface of the lower cheek teeth. If left untreated, these enamel points may continue to lengthen, causing painful ulcers or lacerations of the cheek and tongue. Another common abnormality of the adult horse is the development of hooks on the first upper premolar and last lower molar. These hooks develop as a result of abnormal alignment of the mandibular and maxillary cheek teeth. Hooks may restrict the normal front to back movement of the lower incisors in relation to the upper incisors with change in head position. This is especially important when horses are expected to bend at the neck and poll. Hooks affecting the last lower molar are more difficult to treat due to the depth of the teeth in the mouth, minimal working space and close proximity of the bone and surrounding soft tissues. Minor oral trauma frequently accompanies reduction of these hooks.

Other malocclusions result in steps or waves. A wave is a series of overgrown teeth opposed by a corresponding series of over worn teeth. Although there are several techniques for the correction of steps or waves, these abnormalities may not be correctable in a single dental treatment due to the potential for invasion of the pulp chamber if excessive tooth is removed. Therefore, additional treatment at a more frequent interval (often every 4 – 6 months until the malocclusion is corrected) may be necessary.

Geriatric Horses

Although geriatric horses may suffer from any of the malocclusions previously described for adult horses, the most severe dental abnormality in these horses is periodontal disease. As the cheek teeth erupt, there is a natural tapering of the tooth from the occlusal surface to the root. In young horses, all 6 cheek teeth are packed tightly together with no normal space between the teeth. As the tooth erupts and the occlusal surface is worn, this tapering results in formation of spaces known as diastema between the teeth. Food and other debris can become trapped in these spaces and undergo fermentation. This food packing and bacterial fermentation has a negative effect on the natural defenses in the mouth and infection of the gingiva occurs. With time, this infection migrates along the tooth eventually affecting the surrounding bony and soft tissue attachments of the tooth to the jaw. Periodontal disease may eventually lead to infection of the tooth root, tooth root abscesses and premature tooth loss. Although there are usually no obvious outward clinical signs, this is a painful condition that eventually will lead to difficulty chewing, weight loss and potentially other more serious health problems such as secondary infection of the sinuses and colic.

Treatment of periodontal disease is much more difficult than prevention. Prevention involves routine dental examination and maintenance as previously discussed. Treatment involves removal of all packed feed material and debris, instillation of an antibiotic gel and covering the affected area with dental impression material to prevent further mechanical trauma. A more advanced treatment for periodontal disease is flushing and disinfection using the Equine Dental System by Pacific Equine Dental Institute (P.E.D.I.). This technique utilizes high pressure air abrasion and flushing with sodium bicarbonate (baking soda) and disinfection.  If periodontal disease is severe enough, removal of the affected tooth may be the only viable treatment.

As horses age, eruption begins to slow and the availability of reserve crown begins to decrease. Older horses with significant malocclusion must be treated carefully. Severe steps or waves may be present; however, aggressive treatment especially removing excess crown to bring the teeth into more normal occlusion may result in removal of too much remaining crown, thus permanently affecting the horse’s ability to grind feed. Essentially any sharp enamel structure(s) should be corrected by removal of a minimum of remaining crown. Because formation of these points is dependent on continued eruption and wear, they are usually slow to reform if they recur at all. Finally, older horses’ teeth will expire and either fall out or become cupped. This condition is not correctable and these horses must be managed through dietary modification.

Systemic Manifestations of Dental Disease

Besides the obvious oral manifestations of dental disease in horse, there are several disease processes that can be directly related to disease of the teeth and surrounding structures. Because the last 4 maxillary cheek teeth are embedded in the sinus, infection that travels along the tooth may invade the sinus and surrounding bones. This condition is usually recognized by malodorous discharge draining from a single nostril on the side of the affected tooth. As fluid builds up in the sinus there can be swelling of the face directly over the involved tooth and distortion of the facial bones. Eventually a draining tract may open on the face. Radiographs of the head in these patients will often demonstrate fluid in the sinus and destruction of the bone supporting the tooth and its root. In these cases, surgery is often necessary to remove the affected tooth and drain the sinus. These diseased teeth can sometimes be removed in the standing, heavily sedated patient, but frequently require general anesthesia and opening of a bone flap into the sinus. On many occasions, a small enamel fragment or diseased bone that is not identified at the time of tooth removal may require additional surgery for complete removal.

Abdominal distress or colic is another condition that is highly associated with pre-existing dental abnormalities. Malocclusion of the cheek teeth will prohibit effective grinding of fibrous material. This, in addition to other environmental factors such as failure of the horse to drink adequate water and poor quality hay, may lead to impaction of the large colon, ileum, or cecum.

In older horses, tooth loss commonly leads to esophageal obstruction (choke) because of inadequate mastication (chewing). This condition is also difficult to treat and can lead to esophageal damage and rupture. In addition, if the horse aspirates a large amount of saliva and feed material severe sometimes fatal pneumonia can develop.

Although not completely, each of these conditions to a large degree is preventable by regular dental examination and care.

Conclusion

The importance of comprehensive routine dental care cannot be overemphasized. Many painful and potentially debilitating dental conditions are preventable if appropriate dental care is provided. Not only can the horse be saved form painful conditions affecting the mouth, but the occurrence of potentially performance limiting and life threatening conditions that are expensive to treat and require extended periods of time off may be significantly decreased.

Does Your Horse Have a Dental Problem?

The LSU Equine Clinic is now offering a regular comprehensive equine dental service for routine and advanced procedures. This service will be provided each Thursday. Please contact the LSU Equine Clinic (225-578-9500) for more information or to schedule an appointment.

Colin F. Mitchell, BVM&S, Diplomate ACVS

Assistant Professor, Equine Surgery

LSU Equine Clinic, Equine Health Studies Program

School of Veterinary Medicine, Louisiana State University

Baton Rouge, LA  70803

www.LSUEquine.com

With the majority of lameness problems originating from below a horse’s fetlocks, care of the hoof capsule and its contents are recognized as a vital component of necessary care. Caring for your horse with the aid of a skilled farrier is essential to maintaining your horse’s soundness from birth to maturity. Veterinary input is often needed especially when lameness issues occur. To ensure successful treatment, it is important to localize the lameness to the foot. Your veterinarian can accomplish this by examining the horse, applying hoof testers and using nerve blocks. The results of this will help establish that the area of interest is in the lower limb. Radiographs can then be taken to examine the structures (particularly the bones) within the hoof capsule to identify any abnormalities. If soft tissue damage is also present, other diagnostic imaging techniques such as an MRI, CT or ultrasound exam may allow a diagnosis to be made. Having an accurate diagnosis will allow your horse to receive the correct treatment right away.

So whenever a problem is observed, a good working relationship between your farrier and your veterinarian will help achieve the best results for you and your horse!

Routine foot care is important, and starting this at an early age will help lay a strong foundation for future work and success. Starting early will help ensure your horse becomes accustomed to and comfortable with this “strange new” experience and facilitate proper development and growth of your horse’s feet, which will reduce the risk of problems in later life. Young horses often develop foot problems secondarily to rapid rates of growth, immaturity when born or because of pain elsewhere in their limbs.

Selective Problems in Foals

Flexor tendon laxity is a common problem in newborn foals and can occur in all breeds. The first sign of this is noted when the foal first stands and appears very loose in their fetlock, and if severe they can even be walking on the back of their pasterns. Fortunately, this is a problem that will often resolve rapidly as the foal gets a little stronger and older (sometimes even a day or two is all that is needed) and will not need any other care. However, help may be necessary for the foals that are walking or bearing weight on their pasterns. First, these foals should be confined to a well-bedded stall to reduce the risk of developing rub sores on the backside of their pasterns or fetlocks. Exercise is needed to allow the ligaments to strengthen, but excessive exercise will tire the foal and make the laxity worse. To prevent rub sores (foal skin is very thin and fragile) from becoming serious and the risk of penetrating joints or tendon sheathes, light bandages can be applied to protect the skin. Caution must be taken here as unlike adult horses, the muscles and tendons of foals will become more relaxed in response to tight leg wraps, which is counter productive in this situation. To increase the chance of success and the response time, some intervention by your farrier and veterinarian can be extremely beneficial. To help the foal develop a more upright conformation and keep the pastern(s) off the ground, applying a heel extension to the foot will substantially help. This can either be a glue-on shoe (sometimes difficult to keep on, even in young foals) or by applying multiple wooden tongue depressors (works best in light foals) with either tape or glue. This helps support the lax flexor tendons, and with a little care this problem can often be rapidly alleviated. Once the foal has a more normal conformation, both the mare and foal can have access to a paddock or other turnout as regular exercise is vital if the foal is going to develop healthy tendons, joints and bones.

Aside from being too lax, flexor tendons can also be seen to be too tight in horses. This is usually a problem of younger horses, and is more easily and successfully treated in neonates. Flexural deformities frequently affect the coffin (distal interphalangeal) and fetlock (metacarpo/tarso phalangeal) joints, or less frequently the carpus (knee). In all of these locations, the joint appears to be flexed more than normal, giving the appearance of either a very steep dorsal hoof wall, a fetlock that breaks forward or being over at the knees. These conditions can either be observed at birth (a congenital deformity) or as the foal grows and matures (an acquired deformity). If the deformity is congenital, early and appropriate conservative (non-surgical) therapy will often be all that is necessary to correct the deformity. Acquired deformities often occurs secondary to another problem, either because of pain originating elsewhere in the limb or because of rapid growth of the foal. For this reason, surgical intervention in addition to conservative therapy is often required as these cases are more complex and successfully treat.

Conservative therapy varies depending upon the location and the severity of the deformity. If the deformity is mild, often all that is needed is to ensure that the foal is exercising as this will help to stretch the tendons. Treatment with intravenous oxytetracycline (an antibiotic that binds calcium and promotes muscle relaxation) will often help relax the musculotendinous structures of the legs adequately to return them to normal. Applying “tight” bandages will also yield relaxation of the area that is wrapped, and this effect can be increased by adding a firm splint to the bandage to increase the degree of immobility from the bandage. These bandages should be changed daily and left off for a sufficiently long period to reassess the limb conformation and to determine if re-bandaging is necessary. Some degree of improvement should be observed within a few days.

If these initial conservative treatments are not enough to correct or achieve dramatic improvement, then applying a toe extension in deformities of the distal interphalangeal (coffin) joint can help stretch the tendons and allow them to assume a more normal position. Trimming the toe is contraindicated at this time, and it should be left in place and supported with a toe extension, either using a glue-on shoe or of hoof acrylic. This toe extension acts as a lever arm to force the heel down and stretch the deep digital flexor tendon.

Acquired deformities occur slightly later in life, usually after the foal is 3 months of age or older. By this time, conservative therapy with bandaging or oxytetracycline is less likely to be effective. To ensure the best outcome, veterinary intervention and care by a skilled farrier will achieve the best results. Restricting exercise and the foal’s ration can be beneficial when combined with appropriate hoof trimming, but if no improvement occurs within a few weeks, other treatments should be attempted. Depending on the location of the deformity, desmotomy (transection) of the inferior and/or superior check ligament(s) will help the tendons relax to allow more appropriate conformation. Special hoof care should also be combined with these surgeries, as well as identifying and addressing any other underlying causes. Toe extensions can help protect and normalize the angle of the hoof wall for flexural deformities of the distal interphalangeal joint. Care must be taken to provide protection to the toe, which is often worn short, to not remove excessive hoof from the heel region at any one trim. Changes should be gradual and low doses of phenylbutazone may be used initially to keep the foal comfortable.

Angular limb deformities are also often observed in young foals. These are often described as either valgus (the limb distally is angled outward) or varus (the limb distal to the joint is angled inward) deformities. Mild deformities in newborn foals will often resolve without any intervention, other than confining the foal to a small area until the soft tissues can increase their strength and support the region. When the deformity either is worsening or not improving after a few weeks, some simple care is often all that is needed. To treat a carpal valgus deformity, applying a dorsomedial toe extension is often beneficial because this helps turn the toe in slightly and improve the angulation of the leg. When trimming these feet, a small amount of extra hoof on the lateral aspect can be removed to achieve the same effect, but this can cause other problems if done excessively. We recommend the use of toe extensions and if necessary only one or two passes of the rasp on the outside of the foot every one or two weeks. Cautious trimming, applying extensions and restricting exercise are often all that is needed. Valgus deviations of the carpus are the most commonly seen, but if they remain untreated, the fetlock can begin to develop a varus deformity which can be harder to correct. In foals with deviations greater than 10˚ (radiographs are often needed and used to accurately identify the degree of deviation) surgical intervention is often used in conjunction with conservative therapy. Perisosteal elevation (to accelerate growth on one side), or in more severe cases, transphyseal bridging (to restrict growth on one side) can be used. Following any of these surgeries or corrective techniques, the foal should remain confined either to a stall or small paddock to prevent any exacerbation of the problem, until it has corrected. More severe deviations should be evaluated and addressed by a veterinarian before the foal gets too old. In general, foals with deviations of the fetlock should be examined within 2-4 weeks of age since most of the growth in the growth plate of the distal cannon bone has occurred by 3 months of age and for foals with carpal/tarsal (hock) deviations, the foal should be evaluated by 2 months of age since most of the growth in the distal growth plate of the radius/tibia has occurred by 4-6 months.

Selective Problems in Adult Horses

Adult horses often require special hoof care, especially to support and protect their feet during the athletic endeavors asked of them. Most if not all horse owners have at some time, heard or been associated with a horse diagnosed with navicular disease. This was a “catch all” diagnosis for problems thought to originate from the navicular bone itself or from the heel region of the foot, but with the increasing availability of magnetic resonance imaging (MRI) technology (coming soon to LSU-SVM), diseases or injuries affecting other structures within the hoof, instead of the navicular bone (including ligaments, tendons and other soft tissues and bony structures) have been identified. This does help explain the reason for a poor response to treatment in the past when the lameness was treated more generically rather than tailoring the appropriate treatment based upon identification of a specific injury in each horse. The use of this advanced diagnostic imaging technology and appropriate corrective trimming and shoeing will help optimize the response to therapy, often without the need for surgeries such as palmar digital neurectomies.

Each horse needs to be evaluated on an individual basis so that it can be treated according to the diagnostic findings. Many horses with navicular disease (navicular syndrome, caudal heel pain) will benefit from careful trimming and shoeing. Any abnormalities of hoof balance need to be corrected, either mediolateral (side-to-side) or dorsopalmar (front-to-back), and additional support often needs to be provided to the heel region. Bar shoes (shoes that connect either straight across or in an oval shaped across the heels) can be applied in an attempt to protect and provide support to the heel region and spread the forces applied every time a horse bears weight to a larger area. Other horses, if they also have underrun heels or sometimes an abnormal hoof-pastern angle, will benefit from either a wedge pad to raise the heels and reduce the tension on the deep digital flexor tendon. Full pads can often be used if sensitivity is identified over the heel region until the horse can grow additional healthy hoof, but care needs to be taken as these can trap excess moisture underneath the pad. Using a rim pad will provide the same elevation, but leave the remainder of the sole open to the environment. The fact that each horse is different, and may even have very different conformation and shape to their front feet means that careful examination of each individual horse is necessary to identify the appropriate therapy; what will work for one horse is often contraindicated in another!

For best results, combination therapy is required. In horses with less severe lameness localized to the heel region, use of non steroidal anti-inflammatory drugs such as phenylbutazone (Bute) or flunixin meglumine (Banamine) can help these horses continue to be comfortable. In acute episodes of pain or to maximize the response to corrective trimming and shoeing, injections of the distal interphalangeal joint or navicular bursa with joint medications (hyaluronic acid and/or corticosteroids) can be administered, allowing these horses to continue to perform.

Laminitis is often considered to be a career-ending if not life-threatening condition. Although much has been discovered about its causes and the most effective therapies, once the disease is present and radiographic changes have occurred, corrective trimming and shoeing is vital if the horse is going to become comfortable again. Two chronic forms or manifestations of the disease have been identified, rotation and sinking and these can occur separately or in combination. Rotation is seen when the laminae, which are the soft tissue attachments between the 3^rd phalanx (coffin bone) and the hoof capsule break down and the bone rotates away from the dorsal hoof wall. Sinking occurs when the laminar attachments become so severely disrupted that the entire coffin bone drops within the hoof capsule, and is manifested radiographically by dropping of the extensor process of the 3^rd phalanx below the coronary band; sinkage is a very serious change with an associated poor prognosis. Careful examination of these horses through a physical exam and radiographic examination of their feet is necessary. Whatever condition that caused the laminitis must be identified and treated to prevent further damage, otherwise corrective trimming and shoeing is unlikely to yield good results.

Depending on the degree of change observed radiographically and the comfort level of the horse, trimming and shoeing is usually delayed until the horse is past the acute stage of the disease and things have stablilized. Until this point is reached, the horse will benefit from the application of frog supports (polystyrene foam pads over entire solar surface of foot, custom-made frog supports, etc.) and the use of anti-inflammatory and analgesic (pain relievers) medication, including phenylbutazone. If rotation of the 3^rd phalanx is severe, a deep digital flexor tenotomy may be recommended immediately prior to corrective shoeing. This surgery should not be performed without shoeing as the foot will lose caudal support unless it is protected with appropriate shoeing (often heel extensions are needed). The overall goal of shoeing in horses with rotation is to trim the foot and apply a shoe to reduce the deviation or at least reduce it significantly, while increasing the load bearing to other parts of the foot, such as the sole, frog and heels, all behind the apex of the 3^rd phalanx. Ultimately, the goal is to “de-rotate” and allow the hoof wall to grow out parallel to the 3^rd phalanx. Different shoes, techniques and materials have been used, but the overall goal remains the same. If evidence of sinking is observed, de-rotation of the 3^rd phalanx is not always necessary, but the application of greater support to the sole region and heels is vital in an attempt to make the horse more comfortable. In cases with severe changes, the tip of the 3^rd phalanx can sometimes penetrate the sole of the hoof. This is extremely painful for the horse and requires intensive wound management, to prevent the condition worsening, although this cannot always be prevented.

Unfortunately, no “silver bullet” has been found for treating laminitis, and corrective trimming and shoeing often must be continued until the foot has been able to recover and once again establish more normal laminar attachments. With the decreased rate of hoof growth that these horses display, this can often take nearly a year or longer. Trimming and shoeing is often needed (roughly every 6 weeks), thus dedication and adherence is required on the part of all involved, including the owner/caretaker, veterinarian and farrier. These cases can be extremely rewarding, especially when a horse that was presumed to be beyond saving makes a complete recovery.

Rustin M. Moore, DVM, PhD, Diplomate ACVS

Professor, Equine Surgery

Director, Equine Health Studies Program

Equine Health Studies Program, School of Veterinary Medicine

Louisiana State University, Baton Rouge, LA  70803

Telephone: 225-578-9500/ Telefax: 225-578-9605

E-mail: equine@vetmed.LSU.edu/ Website: www.equine.vetmed.LSU.edu

1. Become familiar with signs of colic, which include going off feed, not drinking, playing in the water bucket, looking at side, pawing the ground, stretching out, repeatedly posturing to urinate, lying down, rolling or violently thrashing.

2. Call your veterinarian immediately when you find your horse showing signs of colic.

3. Removed feed and water from the horse and do not allow it to eat bedding or grass.

4. Walk the horse if it is trying to lie down and roll or thrash violently to prevent self-injury.

5. Do not give laxative agents (mineral oil, epsom salt) via a dose syringe because the horse could inhale these agents and cause severe aspiration pneumonia or pulmonary edema.

6. Do no give any medications to the horse unless directed by your veterinarian. Make sure you give the medications directed by your veterinarian at the proper dose and by the proper route and no more often than recommended.

7. Maintain a written record of the events surrounding the colic, including the time colic was first noted, signs observed, how these progressed/improved, and treatment(s) given (drug, dose, route, time, response).

8. Become familiar with how to take your horses’ rectal temperature, heart rate, respiratory rate and assess the oral mucous membranes for color, moisture and capillary refill time and know what these values are for your horse. Assess these variables when you first find your horse with colic and relay this information to your veterinarian.

9. Make sure the stall, paddock or pasture are clear of objects that the horse might injure itself on while pawing, rolling or thrashing.

10. Locate information for the insurance company (telephone # and policy #) so that the company can be contacted after your veterinarian examines the horse.