Equine Wounds- Brief overview
Most people over their time owning horses will experience their equine getting some sort of cut, scrape, puncture, laceration, or other similar wound. These can range from minor to severe with the appearance unlikely to be adequate to assess severity. Appearance alone may not even directly relate to the type of wound present. In the following short write up, we are going to take a brief look at wounds in horses and break them down into groups for better understanding of what is occurring. This is intended as a guide to better understand the nature of the wound, not to provide medical advice for the treatment of wounds. One should always consult with your veterinarian for proper recommendations and treatment of any wound.
Wounds on an equine can be broken up by several factors. We are going to look at them based on depth, size, and location. Then we are going to discuss just a couple of particularly common wounds
Horses are good at hurting themselves. They can find several things to scrape themselves on and their skin is surprisingly thin in many areas. They do not have hide like we would consider cattle and their cousin the donkeys to have. Being that most horses have relatively thin skin, it is common that they create wounds to it. We can break up these by depth into tissues into scrap, partial thickness, full thickness and deep. For the purpose of this write up, scraps would be our shallowest level and is when only the hair and top of epidermis is removed. These come about when there is pressure applied over large areas during motion most frequently. The points of the hips and edge of the head are common are locations but really any area can be. Scraps may proceed deeper wounds as noted as when impact and deeper laceration started. Scraps are almost always covering an area of the horse in a non-linear fashion and rarely bleed but may ooze. As travel deeper from scrapes, next would be partial thickness skin only cuts or lacerations. These are often more point to point than scraps, the hair is still present, and the skin is opened and are slightly spreadable to be more open. Partial thickness skin only cuts typically bleed. There are no limits on where these can occur on body. Most of these skin only cuts are short in length and appear less than 1/8in deep. Their lack of ability to spread open wide which confirms that not full thickness through skin. If can spread the wound open, then cut travels to our next level of depth- full thickness. Full thickness wounds are common on legs and head. These wounds often times will bleed and are distinguished from skin only by their ability to be pulled wider apart to see underlying tissue. With these, underlying tissue like tendons, muscles and potentially bones can be observed. These can be short or long in length. They do not have to be point to point but can include flaps. If there is visible damage to tissue under the skin (tendons or muscles), then the wound is considered a deep laceration or cut. It is often difficult to fully assess the underlying damage. Swelling, bleeding and other complications are common with these deep wounds. Puncture wounds are included with deep wounds as difficult to impossible to assess damage to underlying tissues. While in general the deeper a wound goes, the more critical prompt medical care is required, it is one factor and shouldn’t negate intervention in more shallow wounds.
Wounds range in size from small to massive and everything in between. They can be as small as a needle poke to as big as lacerations that are several feet long. Size of wound does not correlate to severity in any degree. For example, puncture wounds can be some of the hardest to manage and are typically treated aggressively. Punctures are often serious in part because they are deeper than their surface size which limits drainage and makes full assessment challenging. Their depth makes them more susceptible to infection than most full thickness linear lacerations. Large wounds can also pose as issue if there is significant blood loss or exposed underlying tissue. Damage to muscles and tendons can limit function and mobility. Horses are a prey species and have adapted quite well to being able to quickly heal from large wounds. Large open wounds tend to attract predators so to limit this attraction and to close these wounds quickly, horses develop a type of tissue we call granulation tissue. This highly vascular tissue grows rapidly to fill in the voids left by the trauma to the underlying tissue. It grows so fast that it lacks nerve endings and has no feeling or sensation. The result of this adaptive healing mechanism is that large wounds can be less severe than small puncture wounds in some cases. The initial size of the wound while important is just one factor in deciding the severity and it is important to discuss with your veterinarian any wounds on your horse.
Horses are good at getting hurt in the oddest of ways and locations. They can find ways to create wounds on any part of their body and some locations are more critical than others. Leg wounds are common and because of lack of loose skin, these are often under tension and full thickness with underlying tissue exposure are the norm. There is also limited muscle mass on the legs making the involvement of underlying structures more likely and complicated with tendons, joints, ligaments and even the bones potentially involved. Wounds over joints are particularly concerning as joint involvement is significant complication that can be not only performance career ending but life threatening. Face wounds are notorious for bleeding a lot and are often down to the skull where fractures into the sinus cavities can occur. Most center mass wounds benefit from the presence of extra skin and muscle bodies protecting vital internal structures which help to reduce severity even though these are most commonly large wounds in size and can be quite deep. Wounds to the thoracic have potential to involve the inflation of the lungs and abdominal wounds can be into the cavity creating a significant risk of infection. Hoof wounds do exist, but these are not like most skin wounds in care. Location is critical piece of information when talking about wounds with your veterinarian.
Wound First Aid
All wounds should be discussed with your veterinarian for proper medical advice and treatment. There are things that you can do to improve the healing and prognosis as wait on your veterinarian. Primary closure of wounds will result in best results in most cases, puncture wounds are the exception. By primary closure, I mean that the wound is sutured or stapled closed and edges heal together. The other form of closure is secondary intention which is where new tissue is produced by the body to close the wound. Cosmetics and strength of closure is superior with primary. There are some first aid items that you can do to aid the ability for primary closure. Keep the wound clean of debris (hay, dirt, rocks, etc) which may require covering it. Prompt treatment of the wound will improve closure ability as with time the wound is likely to swell and on areas like the leg with limited skin this puts the closure under tension. Keeping the margins (edges) moist is of critical importance. As the tissues dry, they die. Dead tissue must be removed, potentially resulting in a large void that must be closed. Ointments may be used in a wound but only if they are water based so that it can be easily washed from the wound. Most common over the counter ointments are oil based. If the wound is bleeding actively, stopping the blood loss is a critical first step. The use of torniquets is not recommended, instead direct pressure is advised. There are several techniques to accomplish this including but not limited to gauze or clean cloth being bandaged over wound. It is reasonable to wash the wound with water if visibly contaminated. Bandaging may or may not be helpful. The use of any medications should be at the direct order of your veterinarian. With any wound the tetanus vaccine status of the equine should be discussed. Tetanus vaccines are administered yearly and included in most combination vaccines. Horses are highly susceptible to tetanus, and this is a fatal disease. While not always possible, one should attempt contact with their veterinarian prior to applying any first aid measures to a wound as some common practices are counterproductive and may increase healing time, increase risk of infection, and/or increase scarring.
Specific wound examples
Two types of wounds involving the hoof are common: sole punctures and heel bulb lacerations. Sole punctures are referring to anytime an object punctures through the sole of a hoof. It is important to remember that if you can safely leave the object in place, one should do that. Removal of the item makes difficult to assess the internal track that item took and the structures that it may involve. The second most common hoof wound is heel bulb lacerations. These are lacerations involving the back of hoof and might have part of coronary band involved. Stabilization of this area is critical to limit the formation of granulation tissue and for regain of function.
There are several wounds that can occur on the leg from simple scraps on the hocks, and rope burns to the pasterns to full thickness lacerations over the carpus and deep lacerations in the upper limb. Critical things about leg wounds include the involvement of underlying tissues, motion of the area, and tension of the skin. One must be mindful of the potential involvement of joints, tendons, and ligaments. Some seemingly minor leg abrasions might be concealing fractures to the weight bearing bones of the legs. Motion and the lack of loose skin complicate the healing process on the legs. Almost all leg wounds will require bandaging. Common complication includes excessive granulation tissue (proud flesh). Rare and life threatening complications of leg wounds include fractures and joint infections.
The above information does not constitute veterinarian advice, it is intended for reference only. Always consult with your veterinarian.
San Pedro Veterinary Service- Dr. Alltop, DVM