Horses can produce granulation tissue in wounds faster than other animals. Proud flesh in horses is when granulation tissue grows and protrudes from the wound.
Exuberant granulation tissue is a condition that can disrupt the normal wound-healing process. Proud flesh in horses is a very annoying disorder for the animal and very costly for the owner.
In this article, we will answer all the questions: In which species does proud flesh occur? Can all wounds develop it? How to prevent it?
What is Proud Flesh in Horses?
Proud flesh in horses is a common complication of the second-intention repaired wounds. It appears only on the distal limbs.
Exuberant granulation tissue delays normal wound healing as it exceeds the skin’s level and extends over its epithelial edges.
Due to this chronic wound complication, many animals cannot continue their sporting careers. Horses with proud flesh have persistent claudication, increased limb volume, and extensive scarring.
What Does Proud Flesh Look Like?
Exuberant granulation tissue has the appearance of a continuous overgrowth mass. It always occurs in connection with a wound in the distal part of the equine limbs.
Proud flesh horses’ appearance is usually a granular pinkish-yellow surface. It often bleeds, ulcerates, and becomes infected due to environmental contact. It then exudates, and crusts cover the surface of the proud flesh.
It has no skin to cover it and acts as a physical barrier preventing the closure of the wound that gave rise to it. The normal skin surrounding the proud flesh invaginates beneath it.
What Causes Equine Proud Flesh?
Equines of any age, sex, or breed can develop proud flesh in the wounds of the distal part of their limbs. Even animals of attentive and meticulous owners can suffer from proud flesh.
All horses are susceptible to proud flesh. Why does only the equine species suffer from this type of complication? And why does it only affect the distal part of the limbs?
The specific cause of this condition is unknown. But, the most significant factor is that the secondary-intention wound healing in the distal part of the limbs is complicated—more than in any other domestic species.
The predisposing factors are:
- A microvascular occlusion in the blood vessels at the edges of the wounds leads to oxygen deprivation or tissue hypoxia, delaying wound repair
- The skin in this area is in intimate contact with the bones and tendons. Also, it has little subcutaneous musculature and little elasticity.
- The distal part of the limbs of horses is an area of high movement. Mobility at the edges of a wound and the difficulty of immobilizing it favor the installation of the equine proud flesh.
- The high probability of infections. Exposure to dirt and environmental contamination may complicate healing.
- Foreign bodies, antiseptics, insect repellents, etc., are all irritative factors that stimulate granulation.
- The epithelium formed during healing by secondary intention is fragile and traumatized.
In a study of injuries in horses conducted in 19 schools of veterinary medicine in the United States, the limbs were by far the most affected, with 72% of injuries in the forelimbs and 51% in the hind limbs (Baxter, 1998). The anterior aspect of the tarsus and the posterior aspect of the carpus are usually the most affected.
Wounds on other parts of the equine body heal well in a shorter period.
How to Treat Proud Flesh in Horses
Surgical management is the treatment of choice to remove proud flesh. Thus, a trusted veterinarian should perform such a procedure.
The goals of the proud flesh horses’ treatment are:
- Maintain granulation tissue below the level of the wound edges
- Decrease the predisposing factors of the second intention healing process.
Wound anesthesia is unnecessary since the proud flesh lacks sensory innervation. Physical and chemical restraint may ease work on the limbs of some horses’. Use a scalpel to cut excess tissue from the wound, taking a direction from distal to proximal.
Resection in mentioned direction keeps the surgical field free of blood. Removing the proud flesh below the adjacent epithelial surface promotes epithelialization. Be careful not to weaken the epithelial edges in this process. This management elevates the epithelium above the granulation tissue and reactivates re-epithelialization.
It is essential to pay attention to the macroscopic appearance of the tissue. A proud flesh with draining tracts, areas of necrosis, or exposed bone may have an infectious focus, foreign body, or bone sequestration. The necessary treatment is a surgical exploration to resolve these problems.
Place local medications on the wound after surgical resection of the proud flesh. The veterinarian will choose the best treatment according to each case:
- Copper sulfate or iron perchlorate cream to control the growth of granulation tissue
- Topical antibiotics: Formulations of antimicrobial ointments or creams. Also, silver products, due to their bactericidal and fungicidal effects
- Micronized aluminum: Helps in the healing process and has certain antimicrobial activity. It comes in a spray and protects tissues against dirt and insects.
- Honey: The healing properties were already well known to the ancient Egyptians, who used it as a curative wound ointment.
The most sold medical honey is manuka honey. It comes from Apis mellifera bees and feeds on the nectar of Manuka flowers in New Zealand.
Using medicinal honey or well-selected honey from a local apiary is advisable. Beware of generic store-bought honey due to processing, adulteration, dilution, and pasteurization. These sources of honey are ineffective for wound healing.
The most important medicinal properties of honey are:
- Antimicrobial, both bacteriostatic and bactericidal
- Aid in the debridement of necrotic, infected, and damaged tissues
- Reduce inflammation
- Promote the formation of new cellular components, blood vessels, and collagen production.
- Prevent complications associated with proud flesh and infections
- Honey does not have side effects or contraindications
As a result, wounds treated with honey tend to leave minimal scarring.
Apply honey to the wound area or administer it in medical formulations of gels, pastes, ointments, or lotions. The affected area must be in contact with the honey, especially if exposed bone exists.
When applying honey to a wound, the removal of bandages is painless. A proper prescription for a honey dressing is about one fluid ounce (30 milliliters) of honey per dressing for an 11.81 x 11.81 inch (10 by 10 centimeter) wound.
Long-term treatments with honey are possible, as it does not harm the tissues. A pleasant effect of bandaging wounds with honey is its deodorizing ability.
- Antibiotics: Depending on the results of the culture and antibiogram
- Nonsteroidal anti-inflammatory drugs: Administered as part of treating traumatic wounds.
- Meglumine flunixin is the most used anti-inflammatory because:
- It decreases pain from inflammation
- It improves the animal’s well-being
- It increases circulation, especially in the distal part of the limbs, as horses walk more.
The timing and dosage of systemic medications will depend on the condition of the animal, type of injury, and degree of contamination.
- Vitamins: They play an important role in wound repair. Vitamin A is essential for epithelial health. Vitamin C is necessary for epithelialization, blood vessel formation, and collagen synthesis. Supplementing the animal’s diet with these vitamins is a good idea.
Other treatments are useful in cases of small, proud flesh, recurrent proud flesh, or as an alternative treatment to surgery:
- Cryosurgery. Therapeutic application of liquid nitrogen, which reaches low temperatures -320° Fahrenheit (-196° Celsius) on living tissues to cause cell destruction. Its efficacy in eliminating proud flesh is variable.
- Radiation therapy. Treatment that uses high doses of radiation to destroy cells. The difficulties of the procedure and its limited availability rule it out as a treatment.
- Therapy with intralesional injection of 4% formaldehyde solution. Requires further research to test its efficacy and possible adverse effects better.
- Amniotic membrane dressings. It is a type of occlusive bandage. Stored equine amnion has demonstrated significant benefits on second-intention wound repair:
- Adheres to and takes the shape of the wound surface
- Reduces pain at the wound site
- Being of fetal origin, it has a low immunogenicity, thus producing a very low immune response.
- Controls bacterial contamination and prevents wound desiccation
- Reduce protein, electrolyte, and fluid loss
- Stimulate epithelialization and protect granulation tissue
- Demonstrated a considerable reduction in total wound repair time
- Demonstrated tremendous ability to prevent proud flesh
- The amount of exudate in wounds dressed with amnion is less than those with conventional dressings
- Amnion induces minimal trauma to the wound at dressing change due to its ease of removal after rehydration with saline solution.
Its disadvantage is the economic cost of the product.
- Grafts. Grafts are a part of skin wholly separated from its site of origin and transferred to a recipient site.
Consider grafts in horses when the wound is so large that repair by contraction and epithelialization would be too prolonged. Besides, the resulting scar would be unaesthetic and affect movement.
Benefits of grafts in distal limb wounds repaired by secondary intention in horses:
- Reduced pain
- Minimal desiccation
- An encouraging property is that they stimulate granulation tissue formation without exacerbating it.
Classification of the grafts is according to the donor:
- Autografts. Grafts where the donor and recipient are the same animals. The lateral cervical area under the mane is a suitable donor site and the most used. Also, discrete areas to use are the pectoral area or the perineum (hidden by the tail).
- Allografts. The graft giver is of the same species as the recipient.
- Xenografts. The grafts are from individuals of different species.
The choice of the type of graft depends on the time it will remain in the wound. If it is temporary, use xenografts or allografts. If the grafts are permanent, use autografts. This choice is aesthetic because the hair will grow from the grafts.
- Laser therapies. The application of laser on acupuncture points is handy:
- The main effect is analgesic, so it helps to reduce pain
- Reduces local edema
- Laser therapy Increases blood flow through vasodilatation
- Stimulates healing of open wounds
- Decreases wound repair time
- Ozone therapy. A machine transforms medical oxygen (99% purity) into ozone. The benefits of ozone are:
- Drastic bacterial reduction
- General cellular stimulation. Fast generation of granulation tissue and collagen
- The epithelium on the wound grows, and the aesthetics of the healing is very satisfactory.
The methods of application on wounds on the limbs are:
- Local methods:
- Microinjections in the lesional edge
- Wound cleansing with ozonated distilled water
- Ozonated oil
- Dressings with ozonized creams
- Systemic methods:
- By rectum
- Hyperbaric oxygen therapy. Based on the hyperoxygenation of tissues and consequent acceleration of wound healing. The oxygen dissolved in blood diffuses through all tissues without requiring the red cells. The disadvantage is the cost of treatment. This therapy still needs more research on wound healing in horses.
- Application of pulsed magnetic fields: They harmonize the energy of altered cells. The therapeutic effects achieved are:
- Reduction of pain
- Reduction of inflammation and edema
- Vasodilatation and increase of oxygen
- Faster tissue regeneration
Home Remedies for Proud Flesh in Horses
When we observe a wound in our horse, we must remain calm and notify the veterinarian immediately. We should try to reduce, as far as possible, the contamination of the injury. Yet, even if our intentions are good, most wound-cleaning agents can cause chemical or mechanical trauma. So, we will explain what you can do regarding equine proud flesh wound care until the veterinarian arrives.
Primary management aims:
- Isolate the wound from endogenous and exogenous sources of contamination
- Prepare the surrounding tissue for further manipulation during treatment.
Wash the wound. To do this, we will use cold water from the jet of the hose. At this temperature, the water favors the contraction of the blood vessels. Thus, the hemorrhage or bleeding will tend to reduce.
The pressure the hose provides removes coarse dirt from the surface and washes away bacteria, facilitating healing. But, take special care not to carry dirt remains to deeper planes since we would further contaminate the wound. Do not exert excessive pressure on the wound with the jet of the hose nor test the depth of the lesion at this stage.
Disinfect the wound. The most used substances are:
- Povidone iodine
It can cause tissue necrosis, impair healing and increase infection. Thus, dilute the iodine solution to 0.1% with sterile saline. Prepare this solution by adding 0.17 fluid ounces (5 milliliters) of iodine to 16.90 fluid ounces (500 milliliters) of sterile saline solution. Apply the remaining solution under pressure using a 2.02 fluid ounce (60 milliliter) syringe and an 18-gauge needle at a distance of 3.93 to 5.90 inches (10 to 15 centimeters) from the wound so as not to cause further trauma.
Dilute the Chlorhexidine to 0.05%. At this concentration, it has a long bactericidal and residual activity, even in the presence of organic matter. Higher concentrations compromise wound epithelialization, granulation tissue formation, wound contraction, and decreased tensile strength.
- Acetic Acid (vinegar)
Some scientific studies support using ordinary distilled vinegar, although most people are unaware of its antibacterial benefits. Its low pH is incompatible with certain bacteria, which means it can be effective against contaminating pathogens.
Wait for the veterinarian. Do not apply bandages or use prescription medications. The veterinarian will decide the best treatment option. Many medicines can cause tissue damage.
How Does Equine Proud Flesh Wound Healing Work?
A wound can heal in two ways:
- First intention repair. Usually, surgical wounds. The wound heals fast, and there is minimal granulation tissue formation.
- Repair by the second intention. The wound remains open (not sutured) and will heal independently. It appears on the injuries produced in the distal part of the limbs of horses, which can give rise to proud flesh. Second-intention wound repair is more prolonged, requires more aftercare, and produces non-cosmetic scars.
What are the Horse Leg Wound Healing Stages?
- Inflammation. Inflammatory cells migrate to the wound site to cleanse it of bacteria and non-viable tissue. Besides, they are essential for recruiting more inflammatory and mesenchymal cells.
- Formation of granulation tissue. Fibroblasts, endothelial cells, and macrophages move within the wound space as a unit and depend on each other. They give rise to granulation tissue that fills the wound space. It is the basis for epithelial contraction and migration.
- Wound contraction. The myofibroblasts on the granulation tissue cause the wound margins to move, reducing the wound area. Wound contraction determines the speed of repair and the final cosmetic appearance of the scar.
- Epithelialization. It occurs during the final phase of wound closure and is a slow process. The new epithelium is thin and fragile.
So what happens in horses’ distal limbs for wound healing by second intention to develop proud flesh?
Microvascular occlusion in the blood vessels at the wound edges generates a weak acute inflammatory response. A delay in the inflammatory phase of wound repair gives rise to a chronic inflammatory reaction. The cells involved in this chronic inflammatory response produce chemical mediators that:
- Stimulate the formation of exuberant granulation tissue and
- Inhibit the contraction phase of the wound
Preventing Proud Flesh in Horses
For the proud flesh to be able to develop, a wound must be present beforehand. Without a wound and exuberant granulation cannot form.
Horses, for centuries, have managed to survive thanks to their speed and natural response to fear, often acting at random in the face of danger. Since man domesticated it, the horse has experienced constant threats from various obstacles, such as wires, sticks, metal, and other environmental objects, capable of causing trauma. If we combine these two factors, instinct, and domestication, it is evident that, in this species, there are ideal conditions for the occurrence of injuries.
It is imperative to prevent and reduce the risk of animal injuries. Thus, owners must remove objects and equipment that can harm the horse from the environment, such as metal plates, deteriorated feed troughs with sharp and cutting edges, pitchforks, etc. Also, design the stables, boxes, and stalls so there are no sharp edges, protruding screws, glass in windows, light bulbs within reach of the horse’s mouth, etc. These may seem unimportant details, but trifles cause avoidable injuries.
The Pros and Cons of Bandaging Proud Flesh
Bandages are usually composed of three layers:
- The primary layer or contact layer (dressings):
- Provide an optimal environment and adequate gas exchange at the wound surface
- Promotes epithelialization of wounds
- Protects the wound from infection
- Provides thermal insulation
- Occludes dead space
- Allows atraumatic removal of excessive exudate from the wound surface
- Easy to manipulate
- The secondary or intermediate layer. The materials used should conform to the shape of the affected area:
- Absorbs moisture
- Absorbs harmful agents (e.g., serum, blood, exudate, bacteria, cellular residue)
- Protect the wound from trauma
- Prevent excessive movement of the area
- The tertiary or outer layer. Usually composed of stiffer materials than the previous layers:
- Keeps the second layer in place
- Prevents contamination and trauma
- Decreases tension on wound edges
- Decreases range of motion
Generally, any wound that heals by the second intention will wear a bandage. The advantages of bandaging a wound are:
- Bandages protect wounds from external contamination. In particular, wounds located on the limbs. These injuries are near the ground and so closer to potential contaminants.
- Pressure reduces wound edema and hemorrhage.
- Absorbs exudate
- It increases the temperature and reduces the loss of carbon dioxide from the wound surface. Thus, it reduces the pH, an unfavorable factor for bacterial growth.
- Immobilizes the region, reducing trauma. Yet, continuous passive movement of the wound can affect repair. In a study comparing the effects of constant passive motion with plaster immobilization on similar wounds, they found that wounds subjected to continuous passive motion were stronger, stiffer, and more resistant than those immobilized with plaster (Becker, 2004).
But, new studies revealed that wound bandages in the distal part of the limbs:
- Increase local hypoxia
- Promote the production of excess granulation tissue
- Prolong the repair process by secondary intention
In conclusion, in the distal part of horses’ limbs, wound repair is faster and with less granulation tissue production when leaving the wound unbandaged. So, bandages may not be the treatment to reduce excess granulation tissue. Yet, due to immobilization, minimization of contamination, and tension reduction, this method makes them an essential part of wound care.
Thus, specialists still have no unified consensus on whether to use dressings to treat the proud flesh, as each animal and situation are different, and each wound requires extra care.
So, specialists continue to study the best practices for treating equine limb wounds repaired by the second intention. Some recommendations for dressing after the removal of the proud flesh are:
- Change dressings every 48 to 72 hours (not every day, much less several times a day). Continual changes do not allow the tissue to advance healing or allow ointments to work.
- Be careful when changing the bandage, as the new healing tissue that is growing can come off. Use plenty of clean water for this purpose.
- Then disinfect with 0.1% iodine solution.
- Finally, apply local medications and re-bandage
The dressing will promote proud flesh formation once the wound has filled with granulation tissue. At this point, re-evaluate the possibility of leaving the wound uncovered or with a very light dressing.
A Final Word
Proud flesh is a condition with many unanswered questions. Veterinarians need more studies and research to explain the best possible treatment to decrease the occurrence and recurrence of proud flesh. In the meantime, we can be responsible owners and be aware of the appearance of wounds in our horses. And prevent the incidence of injury as much as possible.
Becker, M. P. W. (2004). Retrospective study of equine clinical records with wounds. Austral University of Chile. http://cybertesis.uach.cl/tesis/uach/2004/fvw494e/doc/fvw494e.pdf