Proud flesh, also known as granulation tissue, is a type of healing tissue in horses that forms naturally as part of the wound repair process. This tissue aids in wound healing by closing the gap between exposed soft tissue and new layers of skin. [1]

Proud flesh can become problematic in horse if it grows excessively and interferes with normal healing. When too much of this tissue grows, it is referred to as exuberant granulation tissue (EGT). [1]

Lower limbs in horses are prone to developing excessive proud flesh because they have minimal soft tissue coverage and reduced blood supply. Additional factors that contribute to EGT include excessive movement of the healing tissue and contamination (infection) of wounds. [1]

To prevent EGT, it’s essential to promptly attend to any wounds, especially those on the lower limbs. Keeping wounds clean, controlling infection, and minimizing movement in the early stages of the healing process can significantly reduce the risk of EGT formation.

Treatment of proud flesh may involve topical medications, surgical removal, skin grafting, and sometimes bandaging or casting. Consult with your veterinarian regarding the best treatment approach for exuberant granulation tissue to support optimal healing.

Proud Flesh in Horses

Granulation tissue is a natural part of the wound-healing process in horses and other mammals. It can develop in healing wounds on any part of the body. Compared to other animals, wounds on horses develop granulation tissue quite rapidly. [1]

This tissue consists of new blood vessels, fibroblasts, immune cells, and an extracellular matrix, but has no nerve supply. It has an unsightly pebbly or granular appearance. Upon microscopic examination, granulation tissue presents as a disorganized population of cells.

The development of granulation tissue enables exposed soft tissues to connect to new layers of skin. This tissue is beneficial in wound healing as it: [1]

  • Helps to prevent infection in the wound
  • Helps wounds contract
  • Provides a surface for skin cells to move across to fill in the wound

However, granulation tissue is also susceptible to breaking and being reinjured.

Exuberant Granulation Tissue (EGT)

Exuberant granulation tissue (EGT) is excessive granulation tissue that impedes normal wound healing. Some horse wounds develop EGT, which grows until it protrudes from the site of injury, occasionally resembling a tumor.

EGT prevents skin cells from covering wounds (epithelializing) and interferes with hair regrowth. It can be very challenging to treat, can delay wound healing, and may result in the loss of use of the horse.

EGT commonly develops in poorly contracting wounds. [1] Skin wounds that are left open to heal are more likely to develop EGT compared to those closed with sutures.

Wounds on the lower leg of the horse, such as over the cannon bone or pastern area are particularly prone to developing EGT. A lack of oxygen due to reduced blood flow likely plays a role in the development of EGT. [2]

Wound Healing Process

Wound healing typically progresses through four stages: clotting, localized swelling, tissue rebuilding, and tissue remodeling, occurring in this specific sequence.

Granulation tissue is needed to fill in wounds situated over tendons, ligaments, bone, and other important structures. This tissue develops before new skin cells can migrate over top of it to repair wounds.

During the normal healing process, granulation tissue is remodeled as its components are synthesized and degraded. This tissue should stop growing once a wound has filled in, enabling wound contraction and coverage with new healthy skin. [1]

Exuberant granulation tissue develops due to an abnormal healing process. When EGT develops, skin cells cannot migrate over top of the tissue to heal the wound. As a result, the granulation tissue grows until it protrudes above the wound, resulting in the phenomenon known as proud flesh.

Factors such as wound contamination, infection, inflammation, and movement can interfere with the healing process and result in chronic wounds. [1]

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Causes of Proud Flesh

The development of proud flesh in horses typically arises from multiple causes and can be linked to any of the following contributing factors: [1]

  • Inflammation: Persistent and prolonged inflammation in wounds is the primary factor believed to promote EGT. An ongoing cycle of inflammation commonly due to re-injury or exposure to irritants and poor contraction can cause granulation tissue to continue growing.
  • Biological Imbalances: An imbalance between the production and degradation of collagen is associated with the development of EGT. Abnormal programmed cell death (apoptosis) impairs the elimination of unnecessary cells and contributes to the development of EGT.
  • Blood Supply: Areas of the body such as the lower limbs have less tissue coverage with a reduced network of blood vessels and limited blood supply. This can hinder proper wound healing and promote EGT.
  • Excessive Movement: Frequent movement and pressure on wounds can interfere with healing and promote EGT.
  • Contamination and Infection: If a wound becomes contaminated with dirt, debris, or bacteria, it can disrupt the healing process and trigger the development of EGT.
  • Poor Wound Management: Inadequate wound care, such as improper cleaning, dressing, or bandaging, can impede healing and contribute to the development of EGT.
  • Delayed Treatment: If a wound is not promptly addressed and treated, it is more prone to developing EGT.

Horses vs. Ponies

Research indicates that horses are more susceptible to developing proud flesh compared to ponies. [3][4]

Upon tissue injury in both horses and ponies, white blood cells initiate an inflammatory response. In ponies, this white blood cell response leads to increased wound contraction, a faster transition to the wound repair phase, and more rapid healing than in horses. [1]

In horses, the inflammatory response to tissue injury is not as pronounced as in ponies and can become chronic. This chronic inflammatory response inhibits wound contraction and promotes the formation of EGT. [1][9]

Research indicates that during the initial ten days of wound healing on a limb, the concentration of a cell signaling protein known as transforming growth factor-β (TGF‐β) is lower in horses than in ponies. This protein plays a pivotal role in wound contraction. [1]

Based on this research, it is hypothesized that wound contraction might be less efficient in horses than in ponies due to a diminished concentration of TGF‐β. [1]

Diagnosis

If you suspect your horse has developed exuberant granulation tissue, it is important to consult with your veterinarian to ensure an accurate diagnosis. Your veterinarian can discern whether a wound on your horse’s body is forming normal or exuberant granulation tissue.

Diagnosing proud flesh in horses is generally straightforward, as the appearance of this tissue is quite distinctive. Your veterinarian will diagnose granulation based on: [1]

  • Visual Examination: Your veterinarian will visually inspect the wound and the surrounding tissues. They will examine the wound for the distinct features of normal granulation tissue compared to EGT, which manifests as an excessive growth of pinkish or reddish tissue with a rough or bumpy texture.
  • Palpation: Your veterinarian may gently touch the wound to assess the texture and extent of granulation tissue growth. They may also evaluate the wound’s firmness and vascularity.
  • Measurements: The size and dimensions of wounds and granulation tissue may be measured to monitor any changes over time.
  • Differential Diagnosis: Your veterinarian may need to rule out other potential causes of wound healing issues, such as infection, foreign bodies, or abnormal growths (neoplasms). Occasionally, other disease processes such as sarcoids, parasitic infection (habronema), fungal infections, or tumors may appear similar to granulation tissue. [1]
  • Medical History: Your veterinarian may ask questions about your horse’s medical history, any recent injuries, and the wound’s progression to gather more information.
  • Skin Biopsy: In some cases, a biopsy may be performed if there are concerns about the wound’s healing progress or if your veterinarian suspects an underlying issue that requires further investigation.

Treatment

Prompt treatment and guidance from your veterinarian are crucial for managing exuberant granulation tissue in horses to prevent complications or worsening of the condition.

The preferred treatment approach for wounds exhibiting proud flesh depends on the extent of tissue overgrowth and whether the tissue is infected or inflamed. In some cases, diagnostic imaging may be used to investigate further.

While there is no definitive treatment strategy for EGT in horses, common treatments include the following:

Medications

Topical steroid treatments can help reduce the excessive growth of EGT. Cortisone can be cautiously administered during the initial healing stage to mitigate the inflammatory response, thereby preventing excessive tissue overgrowth. [1]

Antibiotics may be prescribed to prevent infection if granulation tissue has been removed from the wound site.

In a research study involving eight horses with limb wounds contaminated by bacteria and fungi, the efficacy of four distinct treatments was evaluated. The treatments included 1% silver sulfadiazine cream (SSC), triple antimicrobial ointment (TAO), hyperosmolar nanoemulsion (HNE), and a control group with no treatment applied. [8]

The study concluded there was no benefit from any of the treatments for improving wound closure. The average time to wound closure for all horses was 42 days, regardless of treatment strategy. [8]

Moreover, wounds treated with SSC and HNE required more frequent trimming of the proud flesh than those given TAO or left untreated. [8]

Another study in just three equids suggests topical treatment with copper sulfate, potassium permanganate and glycerine paste can be beneficial, especially following tissue removal. [10]

Tissue Removal

Surgical removal may be required to excise granulation tissue that has grown taller than the skin surrounding it. When this happens, new skin cells are unable to form over the granulated tissue, and wound contraction halts.

Removal of EGT is commonly performed with the horse standing. Horses with large wounds and severe overgrowths of granulation tissue may require general anesthesia.

Your veterinarian will remove enough granulation tissue to make the wound level with the surrounding healthy skin tissue. This enables the skin at the edge of the wound to grow over the wound.

Removing proud flesh can result in a large amount of bleeding due to the tissue’s rich blood supply. However, surgical removal of EGT is not usually painful for horses since this tissue does not contain nerves.

Skin Grafting

In some cases, skin grafting may be used to cover large wounds, promote faster healing, and reduce scarring. Skin grafting is a medical procedure where healthy skin is taken from one area of the body and transplanted onto a wound site.

Bandaging or Casting

To prevent the formation of EGT, some granulating wounds benefit from being left open to the air and not being bandaged. In some cases, bandaging with topical steroids may be recommended.

Research shows that placing bandages or casts over wounds may contribute to the development of granulation tissue by altering cellular activities and oxygen level at the wound site. [1][5]

Dressings applied under bandages and casts can also promote proud flesh by irritating wounds. Occlusive dressings may worsen inflammation and cause wound secretions (exudate) to accumulate. [1]

However, bandages with topical steroids may be valuable for some wounds. Bandaging provides a moist environment that promotes the growth of skin cells, protects healing wounds, and helps to prevent bacterial contamination. [1]

Casts may also help to prevent the formation of exuberant granulation tissue in horses with wounds. Casts reduce movement in highly mobile areas of the body, such as the legs, to minimize disruptions to the healing process. [1]

Wound Dressing

While some dressings can irritate wounds and worsen EGT, silicone dressing is believed to help prevent granulation tissue. [1][6][7] These dressings are made from a soft, flexible material coated with a medical-grade silicone gel.

Prevention

Prevention of proud flesh in horses involves good wound management. Any significant wound should be evaluated and treated by your veterinarian as soon as possible.

If your horse has wounds that appear deep, cover a large area, or are located over critical regions such as joints and tendons, always consult with your veterinarian for guidance.

Examine wounds closely to identify the presence of foreign material, bone fragments, or dead tissue, which can cause inflammation and increase the risk of infection.

Wounds should be flushed immediately, preferably with a balanced saline solution. Once the wound is clean, your veterinarian can help you determine if a dressing and bandage are needed.

Over-the-counter products, such as topical solution, may help to prevent the overgrowth of granulation tissue. Ask your veterinarian what product is best for your horse’s situation.

Some wounds may require debridement, which involves the removal of dead tissue, or they might need to be closed using sutures (stitches) or surgical adhesive.

To prevent the formation of EGT, your veterinarian might recommend modifying your horse’s exercise regimen, particularly to limit movement in the part of the body where the wound is located.

Nutrition and Wound Healing

Nutrition plays a pivotal role in the wound healing process in horses. A well-balanced diet can support the body’s healing mechanisms and provide nutrients to maintain normal tissue repair processes.

Ensure your horse is getting enough protein, vitamins and minerals in their diet. Proteins provide the amino acids necessary for tissue regeneration, while minerals such as zinc and copper play integral roles in collagen synthesis and the overall immune response.

Vitamin C is important for connective tissue and immune support, while Vitamin E provides antioxidant protection and modulates inflammation, both essential for efficient wound healing. Essential fatty acids, particularly omega-3s, also help modulate inflammation and support healthy skin tissue.

The best way to ensure optimal health and efficient wound healing in horses is to feed a vitamin and mineral supplement that supplies all of the nutrients commonly lacking in the equine diet. A well-balanced nutritional supplement will also support hoof health, energy, mood balance and immune function.

Mad Barn’s Omneity is a comprehensive vitamin and mineral formula that provides key nutrients your horse needs to support wound healing and overall well-being. Omneity is formulated with high quality organic trace minerals and contains amino acids, vitamins, yeast and digestive enzymes.

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Summary

Treating proud flesh in horses can be challenging. It is crucial to involve your veterinarian to get a proper assessment of your horse’s wounds and to determine the best course of action.

Timely and appropriate treatment can help ensure a successful healing process and minimize the risk of complications that may arise from exuberant granulation tissue.

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References

  1. Bertone, A. L. Management of Exuberant Granulation Tissue. Vet Clin North Am Equine Pract. 1989.
  2. Sorensen, M.A. et al. Regional disturbances in blood flow and metabolism in equine limb wound healing with formation of exuberant granulation tissue. Wound Repair and Regen. 2014. View Summary
  3. Wilmink, J.M. et al. Differences in second-intention wound healing between horses and ponies: histological aspects. Equine Vet J. 2010.View Summary
  4. Wilmink, J. M. and van Weeren, P. R. Second-Intention Repair in the Horse and Pony and Management of Exuberant Granulation Tissue. Vet Clin North Am Equine Pract. 2005. View Summary
  5. Dart, A.J. et al. Effect of bandaging on second intention healing of wounds of the distal limb in horses. Austral Vet J. 2009. View Summary
  6. Ducharme-Desjarlais, M. et al. Effect of a silicone-containing dressing on exuberant granulation tissue formation and wound repair in horses. Am J Vet Res. 2005.View Summary
  7. Chevalier, J.M. and Pearson, G.B.Amorphous silicate technology produces good results in equine distal limb wound healing. J Am Vet Med Assoc. 2023. View Summary
  8. Harmon, C.C.G. et al. Effects of topical application of silver sulfadiazine cream, triple antimicrobial ointment, or hyperosmolar nanoemulsion on wound healing, bacterial load, and exuberant granulation tissue formation in bandaged full-thickness equine skin wounds. Am J Vet Res. 2017.View Summary
  9. du Cheyne, C. et al. High Numbers of CD163-Positive Macrophages in the Fibrotic Region of Exuberant Granulation Tissue in Horses. Animals. 2021.View Summary
  10. Shivaramu, S. et al. Successful management of exuberant granulation tissue in two horses (Equus caballus) and a donkey (Equus asinus). Large Animal Review. 2021.