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About EHV-1 Equine herpesviruses (EHV) are found in the majority of horses. Most horses have been exposed to the virus and have had no clinical signs or side effects. There are nine EHVs that we have been able to identify worldwide, but EHV 1, 3, and 4 are the strains that have caused clinical disease in horses. EHV-1 specifically has multiple manifestations of disease in horses: neurological form, respiratory form, and can cause abortion and neonatal death. There is also some evidence that it may cause chorioretinopathy (a disease process in the eye). Research has shown that greater than 80% of horses may be latently infected with the EHV-1 virus, but not all horses will develop clinical signs. The Science Behind EHM EHV-1 myeloencephalopathy (EHM) is still being studied today and we are constantly acquiring new information. There are multiple reports of theories describing how the virus causes neurological disease. A single point mutation in the DNA polymerase gene has been associated with neurological disease, causing the presence of aspartic acid (D) or asparagine (N) at position 752. AAEP reports that 80-90% of neurological disease cases are caused by D752 isolates, and 10-20% by N752 isolates. Recently, there has also been a proven association with a single nucleotide polymorphism at position 2254 in the DNA polymerase gene and the occurrence of EHM. The virus can become reactivated and furthers cell-associated viremia delivering the virus to endothelial cells in the uterus and central nervous system. Clinical signs occur due to the vasculitis and cellular damage caused by the virus. Infection of Horses Horses are affected through contact with respiratory secretion, aborted fetuses/placentas, or by fomites (infected objects, such as grooming tack). Following infection, a viremia is established as the virus circulates the body in infected cells. Following this, virus-infected cells are latently infected. Horses can shed virus in nasal secretions as early as day 1 of infection, and can continue to shed the virus for approximately 28 days. The virus can cause disease in infected horses or can re-activate from latency causing clinical disease in the horse. The virus can typically survive in the environment for up to 7 days, but this can vary based on the environmental conditions. Signs of EHM The incubation period of EHV is typically 4-6 days, but has the potential to be longer. Some clinical signs associated with the neurological disease may include: Fever Nasal discharge Hindlimb weakness Incoordination Loss of tail tone Lethargy Urine dribbling Head tilt Inability to rise Diagnosing EHM Clinical signs (neurological signs and fever) and isolation of the virus are how we confirm EHM. Isolation of the virus can be done using quantitative polymerase chain reaction (qPCR) from nasal swabs and blood collection. Treating and Preventing EHM After confirming EHM, implementing a strict quarantine and biosecurity measures under supervision of local and state veterinarians is key. Treatment options include anti-inflammatories and supportive care. Vaccination and biosecurity protection are the two ways to help avoid disease outbreak. No current EHV-1 vaccine has a claim to prevent EHM. Some EHV-1 vaccines can reduce nasal shedding and possibly viremia. By vaccinating your horses, you induce a strong immune response to the virus without inducing clinical disease. It is important to clean tack, equipment and the environment to inactivate the virus. Cleaning first with a detergent or soap to allow for removal of organic material (such as soil) is recommended in order to prevent disinfectants becoming inactive when they make contact with organic material. There are multiple effective disinfectants that will kill the virus, including 1:10 dilution of bleach to water. Other key points for understanding EHM prevention include: Immunity following infection or vaccination offers limited protection Boosting (routine vaccination) contributes to herd immunity to help protect individual horses It is difficult for the body to establish immunity due to “evasion” properties of this virus Early recognition and diagnosis is key Quarantine and close monitoring of suspected cases is important Exposed horses should have their temperature taken twice daily Please note that this virus is still being investigated and new research is constantly being release as we try to better understand EHM. Additional resources: AAEP: Equine Herpesvirus Resources California Department of Food and Agriculture: Equine Herpes Virus References: Allen GP. Risk factors for development of neurologic disease after experimental exposure to equine herpesvirus-1 in horses. American Journal of Veterinary Research 69,         1595–600, 2008 Diallo IS, Hewitson G, Wright L, Rodwell BJ, Corney BG. Detection of equine herpesvirus type 1 using a real-time polymerase chain reaction. Journal of Virological Methods          131, 92–8, 2006 Diallo IS, Hewitson G, Wright LL, Kelly MA, Rodwell BJ, Corney BG.            Multiplex real-time PCR for the detection and differentiation of equid herpes- virus 1 (EHV-1)          and equid herpesvirus 4 (EHV-4). Veterinary Microbiology 123, 93–103, 2007 Dunowska M. A review of equid herpesvirus 1 for the veterinary practitioner. Part A: Clinical presentation, diagnosis and treatment. New Zealand Veterinary Journal, 62,         171–78, 2014a Dunowska M. A review of equid herpesvirus 1 for the veterinary practitioner. Part B: Pathogenesis and epidemiology. New Zealand Veterinary Journal, 62, 179– 88, 2014b Equine Herpesvirus (Rhinopneumonitis). (n.d.) Retrieved March 7 2016, from http://www.aaep.org/-i-173.html Goodman LB, Loregian A, Perkins GA, Nugent J, Buckles EL, Mercorelli B, Kydd JH, Palu G, Smith KC, Osterrieder N, Davis-Poynter N. A point mutation in a herpesvirus      polymerase determines neuropathogenicity. PLoS Pathogens 3, e160, 2007 Pusterla, N., & Hussey, G. (2014). Equine Herpesvirus 1 Myeloencephalopathy. Veterinary Clinics of North America: Equine Practice, 30(3), 489-506.

San Mateo County Large Animal Evac (SMLAEG) provides evacuation services and shelter for large/farm animals in the event of disaster, such as wildfire or flood, or in other emergencies. These efforts include the evacuation of animals, caring for the animals in holding areas after evacuation, and facilitating the return of animals to their owner/agent. SMCLAEG is activated by the San Mateo County Office of Emergency Services, or other first responders, and its efforts are staffed by SMCLAEG's core team members and volunteers. SMCLAEG is an all-volunteer 501c3. The group also provides preparedness workshops and site inspections upon request. HOW TO CONTACT SMCLAEG: In an emergency, call 911. Tell dispatch that you need the services of the San Mateo Large Animal Evacuation Group. BE PREPARED! Visit https://smclaeg.org/preparation to learn more... Steinbeck Equine Veterinary Clinics works with SMCLAEG as their primary veterinary contact to advise on planning evacuations and during emergency evacuations. LARGE ANIMAL EVACUATION RESOURCES: • Monterey County • Santa Clara County • Santa Cruz County • San Mateo County

By Nora Grenager, VMD, DACVIM and Tim G. Eastman, DVM, DACVS, MPVM Many horse owners in central California may have heard of “Pigeon Fever” — and if not, now’s the time to learn about it. Although also seen throughout the southern United States, California is particularly well known for having a high incidence of this disease, especially during the late summer and early fall. The more arid parts of our state are hit harder by Pigeon Fever. Some years the prevalence seems to be much higher than others, with almost a cyclic nature. Pigeon Fever is caused by a bacteria called Corynebacterium pseudotuberculosis that can survive for long periods of time in the soil. The bacteria is likely to penetrate the skin through abrasions, small wounds, or enter by fly bites (most common). Once the bacteria has entered the horse, it proliferates in these warm, moist cutaneous environments. Pigeons actually have nothing to do with the disease, but it historically causes abscesses and dramatic swelling in the pectoral region of the horse, making the horse’s chest resemble that of a pigeon. Other names for the condition include “Dryland Distemper,” “Pigeon Breast Fever,” “Dryland Strangles,” and its bacterial name, Corynebacterium pseudotuberculosis. The typical signs of Pigeon Fever include abscesses anywhere along the ventral midline (i.e., especially where flies bite!) including the chest, sheath/mammary glands, or in small chains along the lymphatic channel of a leg. However, abscesses can develop anywhere on the horse (see facial abscess image). Large plaques of ventral edema are also frequently present adjacent to the abscesses (ventral edema causes sponge-like swelling on the underbelly of horses)(see edema image). Pigeon fever abscesses usually take several weeks to mature, open, and drain, but rarely the infection may be long-lasting and recurrent for over a year. Pigeon Fever should be considered at the top of the differential list in any horse that has a swelling or abscess in a typical location. The diagnosis can be confirmed by culturing fluid taken from an abscess and growing the bacteria in the lab. Uncommonly, C. pseudotuberculosis can instead cause an internal abscess (less than 3% of all cases). Horses with internal abscesses present with fever, weight loss, depression, and sometimes lameness. If a veterinarian suspects an internal abscess, there is also an antibody blood test that can be performed to help rule in or rule out the disease. This blood test is performed at the University of California at Davis and is very affordable. Treatment of Pigeon Fever can vary depending on the severity and the body system(s) involved. Draining the abscess is the mainstay of treatment (see drainage image) but should not be performed until the abscess is mature. If done prematurely, drainage can be painful and the abscess is more likely to recur. The maturity of an abscess can be assessed by palpation (they generally get soft in the middle when they are mature) and/or by ultrasound. Ultrasound is also helpful in determining if there are multiple pockets of fluid and in identifying deep abscesses. Once opened, the abscess cavity should remain open and it should be flushed daily with an antiseptic solution like povidone-iodine or chlorhexidine. Most horses will be completely over the disease within 3 weeks of the abscess being drained. Again, rare horses will have recurrent abscesses. Use of antibiotics is controversial in horses with Pigeon Fever. Many veterinarians recommend against administering antibiotics for external abscesses because of the potential to delay abscess maturation. However, in cases involving internal abscesses, those involving the lymph channels of a leg (“lymphangitis”), or with very deep abscesses that are difficult to drain and are causing the horse extreme discomfort, long-term antibiotics are generally prescribed. While horses affected with external abscesses have an excellent prognosis, internal abscesses have a more guarded prognosis. Once a Pigeon Fever abscess matures and the condition resolves, over 90% of horses will remain immune to the disease in the future. In those rare instances where the disease recurs, it is unknown whether recurrence is due to re-infection or relapse of the original disease. It is possible it is more likely to recur, or even occur in the first place, in horses with somewhat compromised immune systems. Prevention is centered on good sanitation practices and fly control. Quarantine of affected individuals is not generally recommended due to the long distances that insects carrying the bacteria can travel. A vaccine has recently become available from Boehringer-Ingelheim and may be advisable in naive horses at high-risk for disease. The use of this vaccine should be a discussion between each owner and his/her veterinarian. Related resources: Pigeon Fever Presentation Video by Dr. Nora Grenager

Published by the American Association of Equine Practitioners (AAEP) When an emergency or natural disaster occurs, it is always in the best interest of the horses for both the equine practitioner and the horse owner to be prepared. Foreign animal disease outbreaks or other catastrophic events can adversely affect the health and well-being of horses. Preparation is a key part of making sure your horses are safe and taken care of in a crisis situation. One must understand who the other resources are and what their plan is in order for a coordinated response to result. The American Association of Equine Practitioners (AAEP) has collected helpful links to make sure you, the horse owner, have vital information available before a disaster strikes. Learn more...

The Equine Disease Communication Center (EDCC) is an industry-driven initiative which works to protect horses and the horse industry from the threat of infectious diseases in North America. The communication system is designed to seek and report real time information about diseases similar to how the Centers for Disease Control and Prevention (CDC) alerts the human population about diseases in people.

The American Association of Equine Practitioners (AAEP) provides a wealth of information and resources for horse owners on horse health, how to find equine veterinarians and dental practitioners, disaster preparedness, disease outbreaks, and much more. “To protect the health and welfare of the horse” is one of the AAEP’s most important pursuits. The association and its members provide direct benevolent assistance to horses and charitable groups, including rescue and retirement facilities, international aid projects and emergency relief during natural disasters. Key industry initiatives, such as the Unwanted Horse Coalition and the Racing Medication & Testing Consortium, were formed from the AAEP’s sponsorship and commitment to equine welfare and practices in the best interest of the horse. .

Oral joint health supplements (OJHSs) “are a group of nutritional supplements that contain one or more non-nutrient, non-drug ingredient,” according to John P. Caron, DVM, MVSc, Dipl. ACVS, a professor in the Department of Large Animal Clinical Sciences at Michigan State University. With scores of OJHSs on the market, it can be difficult for horse owners to decide which one to try. Below you'll find an outline of the seven-step “ACCLAIM” approach to assessing OJHSs — for more details, see “Oral Joint Supplements for Horses” by Stacey Oke, DVM, MSc, published by The Horse. Below is a list of some common OJHS ingredients and what they may do to benefit horses, with dosage recommendations from the American Association of Equine Practitioners (AAEP). Note that combination products seem to have the best results. Steinbeck Peninsula Equine Clinics veterinarian, Amanda Hedges, reminds us that “Oral supplements rely on research in horses and other species to make claims for effectiveness. Challenges of oral supplements include lack of FDA-regulated supply, mixed results from evidence-based-research, widespread anecdotal claims, and palatability. Oral supplements may be beneficial in that they can be less expensive than some treatments and are relatively easy to administer. It is important to weigh out the cost vs. possible benefit as compared to other therapies, in the long-term.” For more information, see “Options for Managing Osteoarthritis” by Dr. Amanda Hedges.

By Laramie Winfield, DVM, DACVIM, cVA, CVMMP Annual vaccinations are a large part of our preventative health strategy here at Steinbeck Peninsula Equine Clinics. As your veterinarians, we are happy to be one of your main sources of information concerning your horse’s health and vaccines. However, we also realize that many owners would like additional opinions and sources of information. While there are many excellent sources of information available to you on the internet, there are also many sources of information that are misleading, incorrect, and full of misguided advice. The American Association of Equine Practitioners (AAEP) provides a compendium of sound information and Guidelines for Equine Vaccination. Should you vaccinate your horse or not? An article from Horse & Rider titled "Vaccine Wars: The Great Debate" does an excellent job of answering many of the common questions we hear about vaccination and if it is necessary for your horse. We do recognize that some horses are very sensitive to vaccination and alternative vaccine forms and schedules may be best for those horses. Each horse and situation may benefit from a different protocol and we are happy to develop an individual plan for you and your horse. Rabies is a fatal disease that can be transmitted to humans. Given the severity and significance of rabies infection it is included in the core vaccines recommended for horses. The UC Davis School of Veterinary Medicine offers more information in the article "Do Horses Need Annual Rabies Vaccination?" West Nile is a mosquito born viral disease transmitted to horses causing neurologic signs, fever, and in 30% of horses is fatal. Given that available vaccines are highly effective at preventing disease and safe to administer we strongly support the administration of vaccines to protect against West Nile Virus. The California state government monitors new cases an offers a website with updates and more information on West Nile virus.

By Laramie Winfield, DVM, DACVIM, cVA, CVMMP Veterinary medicine has changed in recent years, with more practitioners choosing to become board certified in a specific area of practice. This allows us to have a more precise focus in one particular area like surgery or medicine. To best serve your horse's needs, Steinbeck Peninsula Equine Clinics provide veterinarians board certified in multiple different specialties including general equine practice, surgery, internal medicine, and sports medicine and rehabilitation. Learn more about what it means to be a specialist... Learn more about some of our specialtIes: Equiine Practice Internal Medicine Surgery Sports Medicine and Rehabilitation

By Wade Tenney, DVM Published in Bay Are Equestrian Network in June 2007 There was a time when the only practical use of ultrasound in equine medicine was to diagnose pregnancies and bowed tendons. With recent advancements in ultrasound technology, the image quality has improved tremendously. It is now possible to identify subtle injuries and to image parts of the horse that before now could not be seen. In fact, you may be surprised at the number of ways that ultrasound is being utilized in equine medicine. The cornerstone of ultrasound use in equine athletes still centers around the tendons and ligaments that course down the back of the front and hind limbs. These supporting structures are under a tremendous amount of stress during exercise, making them prone to injury. We are able to evaluate the cross-sectional area (size), echogenicity (density) and fiber pattern of these soft tissue structures. Once the injury is diagnosed, recheck ultrasounds (generally at 60 day intervals) allow the veterinarian to evaluate the healing and strength of the injured tendon/ligament. This information allows the veterinarian to constantly adjust and customize your horse's rehabilitation program to prevent re-injury. The evaluation of joints is another important use of ultrasound in our equine athletes. While radiographs (x-rays) give us important information regarding the bony changes within a joint, we need ultrasound to evaluate the soft tissue structures within the joint. Some of the structures we evaluate include the joint fluid, joint lining (synovium), collateral ligaments, menisci and articular cartilage. The joints that we commonly evaluate via ultrasound include the coffin joint, fetlock joint, hock, stifle, elbow, shoulder and even the temporomandibular joint. By combining the information from radiographs and ultrasound, your veterinarian can get a very thorough picture of the condition of the joint. Ultrasound guided procedures have allowed veterinarians to fine tune many diagnostic and therapeutic procedures. Once the target area is visualized with ultrasound, a needle or biopsy instrument can be introduced and visually guided directly to the target area. For instance, ultrasound can guide a needle into deep joints such as the neck or hip so that they may be blocked or treated with steroids. Ultrasound can aid in the biopsy of deep organs such as the lung, liver or spleen. It can also be used to obtain a sample from a deep fluid pocket or internal abscess. One increasingly popular treatment is ultrasound guided injection of stem cells into a core lesion within a tendon or ligament. Without this useful tool, many disease processes would go undiagnosed or untreated. Fortunately, heart problems are not that common in horses. However, if your veterinarian diagnoses a heart murmur in your horse, ultrasound is an invaluable tool to provide information regarding cause and prognosis of the murmur. Ultrasound can tell us which valve is affected and how severe the regurgitant blood flow is. Ultrasound may also help guide the treatment plan; for instance, the treatment will be very different for a heart valve with an infection versus a valve with a degenerative lesion. Some ultrasounds have specialized programs to determine the size of heart chambers, thickness of walls, and the speed of blood through a valve. This information can be used to give a prognosis and potentially help determine if your horse is safe to ride. Ultrasound of the equine abdomen is more commonly implemented, especially in cases of colic, diarrhea, weight loss and liver or kidney disease. On the right side of the horse, ultrasound can visualize the cecum, right kidney, right liver lobe and right dorsal colon. On the left side of the horse, we can evaluate the spleen, left kidney, stomach and left liver lobe. The small intestine and large colon can be seen throughout the abdomen and can be evaluated based on size, motility and bowel wall thickness. Internal abscesses, such as those associated with pigeon fever or Strangles, may also be visualized with ultrasound. In many cases involving eye trauma, examination of the eye may not be possible due to swelling of the eyelids or severe cloudiness of the cornea. Ultrasound allows the veterinarian to evaluate deeper structures and assess the amount of damage within the eye. The iris, lens, optic disc and retina are all readily visible with ultrasound. This allows immediate treatment to begin without waiting for the swelling to subside so that a complete ophthalmic exam can be performed. As you can see, virtually every part of the horse's body can be evaluated to some extent with ultrasound. Ultrasound is a relatively inexpensive and non- invasive means to gather a lot of information regarding disease processes in your horse. So, the next time your horse presents himself as a "diagnostic challenge" ask your veterinarian if ultrasound might shed a little light on the problem...

By Timothy G. Eastman, DVM, DACVS, MPVM Published in Bay Area Equestrian Network October 2006 Horses are “fight or flight” animals and have a great propensity towards skin wounds which generally occur while avoiding a potential threat, are surprised, or by accident. Oftentimes horse owners are faced with the dilemma of examining a wound and determining whether or not a veterinarian needs to be contacted. The aim of this article is to clarify some differences between wound types with regards to severity and prognosis, as well as provide an overview of current concepts in wound management. Abrasions are wounds involving only the superficial layers of the skin. As they are generally not all the way through the skin, they can not be sutured. They may however be very painful and can cause a great degree of lameness. If severe, they should be closely evaluated to make certain that no portion of the abrasion goes full thickness into an important structure. Generally they respond well to hydrotherapy, sweat-wraps and anti-inflammatories (“bute”). Horses do get bruises or contusions, they are just more difficult to see than in humans because of their thick hair coat. These are treated according to severity. Puncture wounds typically create a lot of necrosis of deep muscle tissue and are generally treated by daily lavage (“flushing”) and antibiotics. Because of the degree of deeper trauma, oftentimes these are not closed primarily but are allowed to heal by second intention. One common puncture wound is nail punctures to the feet. Where the nail goes is of paramount importance and can be very difficult to determine once the nail is removed. For this reason, most veterinarians recommend leaving the nail in place until an x-ray can be taken to determine what structures are involved (see Figure 1: Radiograph (x-ray) showing a nail puncture to the foot that missed all vital structures). Most don’t involve vital tissues and are managed similarly to foot abscesses. Those that involve vital structures (primarily the navicular bursa) are very important and managed aggressively like infected joints discussed later in this article. The most common type of wound in horses is a laceration (“cut”) of the face or limbs. Most lacerations can be sutured if caught early enough and should be evaluated by a veterinarian. Most wounds if sutured will heal in 2 weeks with minimal scar formation. As in people, laceration repairs in horses sometimes fail. If this occurs contact the veterinarian who performed the repair as he or she may want to re-evaluate the wound and change game plans. When a laceration is Radiograph showing a nail puncture to the foot that missed all vital structures. sutured closed, it is said to heal by 1st intention or “direct” healing. A laceration allowed to heal on its own by heals by 2nd intention or “indirect” healing. Sometimes veterinarians allow a wound to be treated under a sweat wrap for 1 or more days prior to closure, this is “delayed primary closure”. Delayed primary closure is sometimes used when a laceration has passed the “golden period” which is the time (approximately 6 hours for the average wound) in which a wound is likely to be managed by suturing because contamination and/or infection has not become established. The BIG thing is that if the wound is over a synovial structure (a joint, tendon sheath or a bursa) it needs to be treated immediately as wounds involving these structures can be life threatening. Tendon sheaths occur in front of and behind most joints of the limbs of horses. They serve to provide fluid identical to joint fluid to lubricate tendons as they glide over bony prominences. A bursa is a synovial fluid filled sac which, like a tendon sheath, serves to facilitate tendons gliding over bony prominences. The navicular bursa is often treated in navicular disease, distension of the olecranon bursa is a “shoe boil”, and distension of the calcaneal bursa is a “capped hock”. It can be difficult to determine if a wound involves a synovial structure (joint, tendon sheath or bursa) but a good rule of thumb is if a wound is within a hands breadth of the middle of a joint, involvement of a synovial structure is more likely. More on this later. So, if you identify a laceration on a horse under your care, the following steps should be taken. First evaluate the degree of bleeding or hemorrhage. If you can “count the drops” as the wound bleeds, you have plenty of time to treat the wound. If however, there is a steady stream of blood shooting from the wound under pressure in veterinary school they preach “Don’t Panic, Apply Direct Pressure, Clamp, & Ligate”. The first two things, don’t panic and apply direct pressure should be performed by the caretaker. Direct pressure will decrease most hemorrhage to a safe level. This can be accomplished with a towel, gauze or even just a hand until a bandage can be applied. Bandage material should be a part of everyone’s first aid kit at the barn and in the trailer. A bandage of just good thick cotton material and “vet-wrap” is generally sufficient to maintain pressure on a lacerated vessel until a veterinarian arrives. If hemorrhage is minimal or it has been controlled the wound should be thoroughly cleaned. Betadyne or Nolvasan are the two anti-septics used most commonly in horses and both are very effective. Cold hosing a wound is a good first line of defense followed by thorough scrubbing with an anti-septic. Once the wound has been cleaned, it is generally safe to apply an antibiotic ointment (Furacin, Nolvasan, Silvadene etc) and a light bandage if possible. This is now the time to contact a veterinarian. You have assessed the wound location and can provide a reasonable description of the wounds proximity to the nearest joint, as well as the thickness of the wound and applied first-aid. It will be the call of the veterinarian whether or not a visit is indicated. If you can pull the skin edges apart, it is a full thickness laceration and most veterinarians will recommend an evaluation unless it’s very small and in a safe spot. Virtually any equine veterinarian can tell you horror stories of very small wounds in a bad spot that were not properly managed and led to the horse’s ultimate demise so they don’t mind being consulted. The vast majority of wounds are superficial and do not involve any vital structures. In general, they will be managed by having the surrounding hair clipped and being thoroughly cleaned, the edges of the skin around the wound “blocked” with a numbing agent (lidocaine or carbocaine) and primary closure will be attempted. Wounds of the lower limb may not be blocked directly but be desensitized by having their nerve supply temporarily deadened. Some wounds because of their location or the nature of the patient require general anesthesia. Oftentimes, wound edges will be “freshened up” by trimming the margins. This makes a traumatic wound more like a surgical incision which tends to do better. Whether or not they will need to be covered by a bandage generally depends on veterinarian’s preference as well as location (most wounds of the lower limb are bandaged). The same is true about indication for antibiotics. All wounds and circumstances are different and some don’t mandate antibiotics at all while others require several weeks of intravenous antibiotics. Most are managed with oral antibiotics administered by the owner under the guidance of the veterinarian. The lower legs and face are probably the most common sites for lacerations. Wounds around the face have a very good blood supply and usually heal very well with primary closure. In many instances, the same wound on a leg would be allowed to heal on its own but on the face closure is attempted. Typically the sutures will be removed from any of these wounds in 12-14 days. Wounds involving the foot, especially the heel bulbs are under a lot of tension while horses walk which is why they are frequently managed by a “foot cast” (see Figure 2: A foot cast extending up to the mid-pastern area). This is a cast that you can generally manage at your barn as it does not extend up above the fetlock. Heel bulb lacerations tend to heal much better in these casts and you actually probably save considerable money in the long run as several bandages typically cost more than one cast. These casts are typically removed in 2-3 weeks. Another way to manage wounds that are under tension, especially those further up the limb is the use of “stents”. Stents are just devices that distribute the pressure of the suture over a wider area. This can be accomplished with plastic tubing placed between the suture and skin, buttons, and a whole host of other ways. Lacerations involving joints are a whole different thing. Once a wound communicates with a synovial structure, it is assumed that the structure is infected, and it does not take very many bacteria at all to do this. Septic arthritis is the result of an infected joint and due to the damage the bacteria cause to the cartilage and surrounding structures as well as the amount of pressure exerted on the joint capsule as fluid pressure rises, horses can be as lame as if they had a fracture. The resultant arthritis can be severe enough to cause permanent lameness. Also, the “good leg” opposite the wound now has to bear more than its fair share of the horse’s weight which can lead to laminitis. Whether or not a synovial structure is involved is the first thing your veterinarian will try to determine. If that assessment cannot be made visually, further precautions are necessary. If a wound is near a joint for example, the surrounding area is typically cleaned very thoroughly and a sterile needle will be placed into the joint away from the wound (see Figure 3: Sterile fluid being injected into a fetlock joint to determine if the wound communicates with the joint). The joint is then distended with sterile saline and the wound is closely inspected for fluid leakage. If fluid injected from a syringe away from the wound comes out of the wound, you have communication from the wound to the joint and a life threatening condition. The good news is modern medicine has made huge advances in the management of infected joints. The bad news is it is not always successful and is very expensive to treat. Infected joints are generally treated by lavaging large volumes of sterile fluid through the joint to flush out the bacteria and the toxins the bacteria produce. This is typically done under general anesthesia. A regional limb perfusion is a procedure that can also be of tremendous value (see Figure 4: A regional limb perfusion of a horse with an infected joint). With a regional limb perfusion the target area of the limb is isolated by one or two tourniquets, and a large dose of a very potent antibiotic is placed in a vessel near the wound. The tourniquet holds the antibiotic near the wound for 20-30 minutes and allows the area to be “supersaturated” with the antibiotic. The levels of antibiotic achieved at the wound are not attainable by conventional routes. Systemic antibiotics will also be a big part of the management of these wounds and are typically given by the intravenous and or intramuscular route as these antibiotics are usually better suited than oral antibiotics. The prognosis for soundness varies tremendously with wounds involving infected joints and are determined on a case by case basis. Lacerations involving tendons are another major cause for concern. The tendons of the distal limb run directly in front and behind the legs. If while examining a wound you notice glistening white tendon like material in the wound, have a handler hold the horse still until a veterinarian can get there as soon as possible. The severity of tendon lacerations depends on location and extent of damage. In general, tendon lacerations of the front of the limb (“extensor tendons”) do well, lacerations involving the tendons of the back of the limb (“flexor tendons”) are serious. Full thickness involvement is obviously more serious than partial thickness ones as is multiple tendon involvement more serious than single tendon involvement. Hindlimbs have a better prognosis than forelimbs with tendon lacerations and infected joints because they don’t have to bear the weight of the head and neck. Flexor tendon lacerations are generally managed with some form of cast or splint and prognosis for full athletic soundness varies but is not typically great (see Figure 5: A splint supporting the back leg of a horse with a severe flexor tendon laceration). In summary, most wounds should involve at least a phone call to your veterinarian, especially if they are near a joint or tendon. Being familiar with basic anatomy will be of tremendous value in helping describe wound location and how serious they are. Have your veterinarian help put together a first-aid kit for your barn or trailer and become familiar with its contents. Doing all the initial steps right are the biggest keys to a successful outcome.

By Timothy G. Eastman, DVM, DACVS, MPVM Published in Bay Area Equestrian Network August 2007 After Kentucky Derby winner Barbaro underwent surgical repair of a severe fracture many equine veterinarians were hearing the same statement “I didn’t think you could fix a broken leg in a horse.” The truth is some you can and some you cannot. This article will describe recent advances in fracture fixation in horses and attempt to clarify why some fractures are considered “good” fractures and some are considered “bad.” The first sign of a fracture is generally a non-weight bearing lameness. The first thing to rule out is the most common cause of severe lameness in horses, the foot abscess. With foot abscesses the foot is frequently warm and the pulse to the foot is increased. Start at the hoof and work your way up the limb applying pressure every several inches around the limb to check for other sites of pain, heat or swelling. The horse should be confined and a veterinarian called immediately to help differentiate the two. Sometimes with fracture of major long bones the diagnosis is unfortunately very easy due to instability of the leg. With some fractures the goal will be returning a horse to full athletic soundness. In other instances you are attempting to save their life for “pasture” soundness. Which ones are good and which ones are bad can be very surprising and should be evaluated by someone specializing in fracture repair. The cost associated for repair of many fractures can vary tremendously depending on the duration of hospitalization, number of implants (plates and screws etc.), type of surgery needed etc (See Figure 1: Radiograph showing use of large number of implants). The biggest challenge facing equine surgeons with regards to fracture repair is the fact that horses for the most part need to remain weight bearing on all 4 limbs. This is true even in the case of a fracture. If a person has a serious fracture of a limb, we are generally confined to bed rest for long periods of time and then transitioned to a wheel chair or crutches and possible a walking cast if all goes well. Horses need to be able to put weight on a fractured limb immediately after surgery. Add in the fact that many of our equine patients weigh well over 1,000 pounds and are “fight or flight” animals and the challenges become obvious. Most fractures even in large horses could be repaired but the opposite (“good”) leg needs to be able to bear weight. If the good leg supports too much of the horses body weight for too long a period of time, the support structures of that leg start to break down frequently leading to laminitis. This is why it is better to have a fracture of the hind limb than of the forelimb. Forelimbs must also support the weight of the head and neck. Laminitis of the “good” leg is called “support limb” laminitis and represents one of the most serious forms of the disease (this is what ultimately led to the demise of Barbaro). Body weight is the primary reason that fractures in foals and ponies tend to carry a much more favorable prognosis than full sized horses. In general, most fractures in foals less than approximately 500-600 pounds are candidates for repair (see Figure 2: Radiographs showing cannon bone fracture in foal and repair). As body weight increases, the biggest determining factor for prognosis becomes the bone involved. In general, full sized horses with a fracture below the knee or hock may be candidates for surgical repair. Fractures above the knee or hock in full sized horses carry a poor prognosis unless the bones are not displaced at all. X-rays are generally needed to provide an accurate prognosis. Other factors include where in the bone the fracture occurred (i.e. how close to the middle), whether or not the fracture extends into a joint, the number of pieces involved, and whether or not the skin over the fracture is intact (a “closed” fracture) or has penetrated the skin (an “open” fracture). The first-aid applied can be of paramount importance in improving chances for survival. Equine veterinarians are trained in how to best prepare a horse with a fractured limb for transportation to a surgical facility. Improper first-aid can lead to a closed fracture becoming an open one. In general, open fractures have a much lower prognosis and a much higher cost associated with treatment. The reason for this is the next big challenge in fracture repair, infection of the implants can be a very serious complication and repair of open fractures have a higher incidence of infection. As bacteria gain access to the stainless steel implants they may secrete a “biofilm” that can prevent the access of antibiotics and lead to loosening of the screws and plates used in a repair. Antibiotics given intravenously or intramuscularly often are not sufficient to combat infected implants and a race may begin where the fractured bone hopefully heals before infected implants need to come out. Some of the biggest recent advances in fracture repair in horses have been in the treatment and prevention of infections. There are very few implants used in fracture repair in horses that are designed specifically for horses, most are made for people. Although it seems intuitive that horses would just need much bigger plates, the laws of physics and the amount of skin present limit the size of the plates that may be used. Plates used in fracture repair are designed to compress the fractured bone ends together. Plates and screws are oftentimes not sufficient to allow a horse to bear weight after surgery so some type of cast is frequently needed. A “transfixation cast” is sometimes placed due to the fact that this type of cast can support the majority of the weight of the limb (see Figure 3: Transfixation cast). With transfixation casts, large pins are placed through the bone above the fractured bone and then incorporated into the cast. This transfers the weight of the limb through the pins to the cast. These casts are not without risk as additional fractures can occur through the holes used to place the pins. However, the added protection of a transfixation cast can sometimes be the difference between success and failure. One of the most stressful times in repair of a fracture is getting the horse from the operating table to back on their feet. Options to help minimize the chances of the repair falling apart include pool recovery systems like used on Barbaro at New Bolton Center, recovering in a sling, or using a system of ropes on the head and tail to assist in standing (see Figure 4: Horse recovering from anesthesia in a sling). In closing, surgical repair of fractures in horses will always remain a huge challenge for equine surgeons due to the above mentioned factors. However, many fractures that were once hopeless are now fixable. If you suspect your horse has a fracture work with your veterinarian to decide whether or not surgical repair should be attempted. Even though fracture repair has made huge advances in recent years, it can still be a major undertaking and the risks and benefits should be thoroughly weighed before choosing repair.