We see the blood….our hearts sink. Horse wounds are a horse owner’s worst nightmare.
We all hear the horror stories of how long wounds take to heal, the money it costs, not to mention how trying to prevent proud flesh is nearly a full-time job in itself.
There are so many wives tales, potions and treatment options that determining what to do can make leave us scratching our head in bewilderment.
In this article, I discuss how wounds heal and how to prevent proud flesh. Luckily for us, wounds do heal and it doesn’t have to be an expensive exercise that many will have you believe.
How Do Wounds Heal?
There has been a large amount of research on how equine wounds heal, but unfortunately, we still can’t speed up how fast this occurs.
What we can do, is improve the quality of the healing and prevent proud flesh by ensuring that we treat wounds so that they heal in the most optimum way.
What we do need to remember is that not all wounds are treated equal.
How we treat some wounds may be contraindicated for others i.e wounds over a joint vs a wound on the gaskin vs a wound on the cannon bone.
It is important to understand how wounds heal so that we can choose the best method of treatment to aid healing.
There are three main phases in wound healing:
Phase One: Inflammation
This occurs immediately when the wound occurs.
Initially, blood vessels constrict to try and prevent bleeding. Soon after they actually dilate and platelets rush to the area to form a clot with thick gooey fibrin.
The dilation of blood vessels also allows other cells such as antibodies, white blood cells, growth factors, enzymes and nutrients to migrate and enter the wounded area.
During this time we see heat, pain, redness and swelling. A lot of oozing of exudate occurs due to the activity of these cells, particularly neutrophils and macrophages.
These cells act to ‘clean up’ the wound, however, if the response is too strong then that is when we see pus. Too much inflammation can be bad and delay healing. It is a fine line.
Don’t be scared of seeing all this exudate on a bandage. It is the body’s response to inflammation and shows that the immune system is doing its job.
Phase Two: Proliferation
Phase two is when new tissue grows. It is a multistep process where the wound is rebuilt using a process called angiogenesis.
Blood vessels proliferate and help transport oxygen and nutrients to the collagen and extracellular matrix that makes up the granulation tissue.
Approximately 8-10 hours post-injury, epithelial cells are proliferating and crawling over the top of this extracellular matrix providing a ‘cover’ of new cells that will make up the new skin.
This is the most important stage of wound healing and any disruption to this causes a delay in healing.
Healthy granulation epithelial tissue does not bleed and is a nice light pink colour.
Horses are a little bit special and like to produce a lot of granulation tissue or proud flesh (sometimes referred to as “exuberant granulation tissue”.
This can be counter-productive as it impedes epithelisation and therefore needs to be kept under control. Skin cells can’t migrate over proud flesh prolonging healing time.
Stage Three: Maturation
This occurs once the wound has closed over and can actually take a very long time. The process involves the wound improving tensile strength so that it is fully functional and won’t split open again.
Collagen is realigned and cells that are no longer required undergo a programmed cell death called apoptosis.
Wound edges contract and slowly the whole area is covered in skin. Whether a scar forms has a lot to do with how much inflammation and movement was present in this whole process.
What Is Proud Flesh?
To understand how to treat and prevent proud flesh it’s good to understand what it is. Essentially it is exuberant granulation tissue.
Granulation tissue is the connective tissue that fills a wound. Healthy granulation tissue is a nice pale pink in colour.
It is made up of lots of blood vessels and doesn’t contain any nerve endings. It likes to be moist.
When a wound is healing, granulation tissue will fill the wound until it is level with the skin edges. This can take months to achieve if conditions aren’t optimal for healing.
Horse leg wounds are very prone to proud flesh. We see the granulation tissue continue to grow outwards and bulge over the skin edge. This makes it very hard for skin cells (keratinocytes) to move across the granulation bed.
Unhealthy granulation tissue i.e. proud flesh is usually a dark red colour, it bulges out from the surface and sometimes has cracks in the surface. Touch can cause it to bleed profusely.
Why Does Proud Flesh Occur?
No one really understands why horses are prone to proud flesh and why it occurs.
The main theory is that prolonged inflammation of the wound delays healing. Horses seem to have a weaker immune response to initial injury, maybe due to lower oxygen levels in wounds of the lower leg.
This means that the cells used to fight infection aren’t getting to the wound and low-grade infection is always present.
Horse legs also don’t have a small muscle called panniculus carnosus. This muscle helps with wound contraction and it’s absence means that leg wounds take longer to heal as skin edges don’t contract as readily.
Movement plays a major role in the formation of proud flesh. Joint and tendon movement tears any bed of tissue and skin cells resulting in inflammation and delayed healing.
Preventing The Development Of Proud Flesh
I would say it’s nearly impossible to prevent proud flesh totally, however, we can definitely minimise its formation.
The principles of wound management need to ensure that epithelisation occurs well so that exuberant granulation tissue doesn’t form and we get skin cells covering the defect as soon as possible.
Factors that impede epithelisation include:
- Drying out (dessication)
- Excessive granulation tissue (proud flesh)
- Extreme cold
The series of pictures below demonstrate a wound that is healing well over the course of 6 months. This wound had weekly bandage changes for quite some time. A veterinarian also cut off excessive proud flesh so that skin cells at the edges could migrate across easily.
It is also important to note that while many wounds can be managed very successfully without too much veterinary involvement, those wounds that occur over joints and tendons do require veterinary assessment.
In these situations the risk of infection is very high and death of your horse can be an avoidable consequence.
Also note that Tetanus Vaccination is a MUST. If your horse has not been vaccinated within 5 years then a booster and a tetanus anti-toxin will be required.
How To Manage A Wound
- Most wounds are terribly contaminated. Get a hose and don’t be scared of using it. (Ensure water is drinkable i.e is clean!).
- Remove hair bordering the wound: apply KY jelly liberally all over the wound.
- Use a shaver or clippers to remove hair that borders the wound. The use of KY makes it easier to remove any hair as it gets stuck in the wound. It isn’t totally necessary….but works well!
- Clean the wound with either a product containing chlorhexidine or a betadine. A soft scrub brush can be used for this (vets can supply). Don’t be scared to lightly ‘scrub’ the wound.
- Don’t forget “the solution to pollution is dilution”, you can never wash a wound too much.
Creams and Potions – How To Maximise Healing & Prevent Proud Flesh
- You want to encourage an environment that promotes epithelisation. The most important principles in wound care are to keep the wound clean and moist during healing. Any product that is moist and has NO caustic properties will do the trick.
- DO NOT use clays and poultices….these dry out wounds and do NOT promote good epithelisation. They are also usually dirty from people putting hands in the pot frequently. They don’t promote oxygenation to the area. Healing will occur, it will just be less than optimal and will likely take a lot longer. They don’t prevent the formation of proud flesh.
- Avoid creams with steroids in them. These also do not promote epithelisation.
- Use products that promote moisture and oxygenation: Manuka honey, Intrasite Gel, Paranet gauze, silver sulphadiazine (for infected wounds).
- Used to keep the wound clean and moist and promote epithelisation. Can help prevent excessive movement.
- Try to keep the bandage on as long as possible between changes. This is very dependent on the amount of exudate (moisture coming from the wound) present.
- Most wounds can be rebandaged every 5 days or longer.
- Daily bandaging is often NOT recommended unless there is copious exudate. Daily bandaging disturbs epithelisation and can result in increased proud flesh production.
Management of Proud Flesh (Exuberant Granulation Tissue)
- Wounds on horse legs seem to be very prone to proud flesh.
- Proud flesh is the tissue that is exudes out from the wound and is very vascular, bleeding at only a slight touch. It is bad as it doesn’t allow skin cells to move in from the wound edges ie. epithelisation.
- The best treatment is to have your veterinarian surgically cut the proud flesh off. This is not painful as there are no nerves, only blood vessels. Expect plenty of bleeding!
- Caustic creams can be used….however take care that these ONLY go on the proud flesh and do not creep onto the edge of the wound. It is difficult to use these properly. If the caustic cream touches the wound edge it will kill healthy skin cells and prolong healing. It is much better to avoid using these.
Take Home Message
- Keep wounds moist
- No clays or poultices
- No caustic creams
- No steroid containing creams
- Keep bandaged to prevent movement
- Avoid infection
- Clean thoroughly (may not actually need antibiotics- we don’t want to encourage resistance)
- Contain/Remove Proud Flesh
- Caustic creams (be very careful avoid if possible)
- Surgical removal far superior
ENSURE TETANUS VACCINATION STATUS IS UP TO DATE
What are your favourite ways to treat a wound? Tell us in the comments below. Remember if you need help with a wound, our vets have years of experience with horses and can advise you how to treat with an online consultation. You can book your consultation here.
Learn all about equine wounds!
How to treat
What NOT to do
First steps in an emergency
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Posted by Your Vet Online on Tuesday, 30 January 2018