A large percentage of the veterinary daily consult consists in dermatologic conditions. While most of them are caused by parasites, such as ticks, fleas and mites; or by fungi, bacteria or allergies, others do not have such a precise or targeted treatment. These skin conditions include sharp wounds, chronic deep skin wounds, burns, secondary wounds due to chronic larval, fungal or bacterial infection, endocrine disorders, even genetic diseases, etc.; some of which can be partially treated with PRP and have impressive results.
The skin consists of different layers with different functions. The outer layer is the epidermis, where the main body-environment layer is, and different types of cells can be found. The principal ones are the keratinocytes, which have a very rapid rate of replacement and produce the dead cells commonly known as shed skin material. Melanocytes are also found in the epidermis, as well as Langerhans cells (immune cells) and Merkel cells (sensory cells). Next to the epidermis goes the basement membrane zone, which acts as a glue between the epidermis and the dermis. The third layer, the dermis, is the one that is significantly irrigated by blood vessels, produces collagen and elastin, is responsive to the environments stimuli such as pain, heat, etc. and also has immune cells. The appendages of the skin include mostly sebaceous glands and hair follicles, and in some areas even sweat glands (feet in the case of dogs). The sebaceous glands produce sebum, an oily substance that moisturizes the skin and hair follicles. The hair follicles are usually compound, having a central hair and many secondary hairs from the same pore. Sweat glands are not that relevant in dogs, since they cool their bodies through panting and drooling. The inner layer is the subcutaneous layer, which is mainly fat tissue that helps maintain fluids, energy and electrolytes in storage.
The main concern regarding skin wounds is the depth of them in terms of the skin layers. The deeper the wound is, the longer it takes for the tissue to regenerate and create a scar, and with time comes the higher risks of severe bacterial infection, necrosis and other complications; so to determine the severity of the wound and the proper treatment, a precise diagnosis on which skin layers are damaged is necessary. It is important to highlight as well, that some injuries are added with a certain level of difficulty regarding treatment because of their extent in terms of body surface, or because suturing is not an option due to the presence of pus and the probability of developing an abscess.
Meet the Wounds
Although sharp wounds are very common, bloody and painful, these are regularly the easier ones to treat if the patient comes in to the veterinary consult quickly. The main concern in these cases is to assess if any internal wounds are happening, and to perfectly clean, sterilize and approximate the wound, leaving it to heal by primary intention.
However, some patients do not or cannot receive veterinary attention immediately, for example, sharp wounded rescued dogs and cats, or pets left alone during holidays or long weekends. Other patients may suffer from other primary causes, like fire or oil burns, and more commonly chronic diseases, such as mite infestation, dermatophytosis, pyoderma, diabetes mellitus, pancreatitis with DIC, myiasis caused by the blueblottle fly, vasculopathies and some genetic skin disorders like epitheliogenesis imperfecta, cutaneous asthenia, epidermolysis bullosa, among others.
These patients will probably come in with deep and/or large wounds, foreign objects nailed into the injury, worm-like insects in the case of myiasis, most likely bacterial infection with purulent discharge and sometimes even necrotic tissue; all of which makes them unfit for primary healing with closure of the wound, because of the lack of skin to perform the approximation, or the likelihood of developing severe complications, such as infectious abscesses, muscle loss, necrosis, dehydration, sepsis and death.
The adequate treatment when treating a complicated wound consists of two parts:
- Primary attention: clean-up and treatment of primary cause.
Stabilization of the patient with intravenous fluids if necessary (always with burn patients, in which dehydration is always a concern), antibiotics and pain management medication should be provided at all times. Additional treatments will vary depending on the disease or cause that originally generated the wound (endocrine treatment, betadine washes, antiparasitic agents like pyrethrins, etc.). Most of the times, sedation or anesthesia is needed, in order to debride necrotic tissue and perform a thorough cleaning to eliminate pus, blood, fibrin, adherences, worms, bacteria, foreign objects, hair, dirt and other contaminants.
- Regeneration of the skin tissue.
Complicated wounds should be kept open for proper drainage and within days, achieving healing by secondary intention, which means formation of granulation tissue, fibroplasia, epithelialization and angiogenesis, leading to a scarred tissue. While this process happens, many different treatment options have been tried in order to prevent the wound from infection, as well as to accelerate the formation of granulation tissue. Natural honey patches have proven to have good antibiotic and healing effects. Sugar, although a little uncomfortable for the patient, has also proven to help heal, as well as maintain the wound dry, thus decreasing the risk of secondary infection. Other kind of natural, herbal and pharmacological patches are also conventionally used (olive oil, aloe, Neosporin, topical steroids, etc.).
The role of PRP in skin regeneration
Platelet-Rich Plasma has shown truly amazing results in substituting secondary healing accelerators because of its noble composition. Providing platelet growth factors, especially Transforming Growth Factor-β in for skin healing, stimulates collagen production and induces the generation of granulation tissue and epithelialization much faster than other agents. Other growth factors also participate in avoiding necrosis and accelerating neovascularization or angiogenesis. In addition to this, several authors like Mark RE et al. (2014) have reported that PRP also has hemostatic and antimicrobial properties, so not only it helps in terms of regeneration, but also preventing the most common complications.
Some patients may not be stable enough to afford an enough blood draw to produce PRP, or in the case of burn patients, their physiological functions may be altered and affecting platelet functions, but this should not be a problem, since platelets are not highly allergenic. The PRP therapy does not necessarily have to be performed using an autologous PRP preparation. Allogenic platelets can also be used, just as long as the donor dog or cat is clinically healthy and tested for blood-borne diseases.
The PRP skin therapy can be applied in gel or liquid form, a decision that should be made individually, taking into account the very patient’s needs. The advantages of the liquid form is that the preparation is faster, since the blood only needs to be centrifuged once and the whole plasma can be used; the disadvantage is that the application is dermatologically restricted to intradermal or subdermal injection, which means that this is a procedure that can only be performed later on in the healing process, when some of the skin layers are already regenerated; this is mostly used after skin grafts are placed, burn patients and wounds that already present granulation tissue. The PRP gel is a product that can be used earlier in the healing process, even from the very start of it; it is obtained in the same way than conventional PRP, but has to go through more than one centrifugation so that the platelet-normal plasma and platelet-poor plasma can be discarded, leaving a more thick liquid that can even be diluted with an equal volume of saline solution without losing its jelly-like consistency. PRP gel should be applied topically onto the wound daily or every other day, depending on the specific wound characteristics of size, depth and level of complications.
This is not just talk: a clinical study made by plastic surgeons Waiker et al. (2015) compared PRP with conventional products used as skin graft adhesives, and results talk for themselves, showing that PRP not only permitted better graft take, but also showed other antimicrobial and scarring benefits on their patients.
Also, a clinical case report made by Tae-ho Chung et al. (2015) published in the Irish Veterinary Journal shows truly astonishing results in a Miniature Pinscher with acute pancreatitis, DIC and a large skin lesion on the hip region and tail that progressed to necrosis in 3 days. They used allogenic PRP gel along with the rest of the treatment (antibiotics, betadine washes, and the pancreatitis/DIC indicated pharmacotherapy), and in only 28 days the lesion was fully recovered, the skin regenerated, a very small scar and hair growth already beginning. Anyone who has ever treated a large wound would know that 28 days is extremely little time to achieve this kind of results.
Needless to highlight, PRP works, and is an excellent, affordable and invaluable tool in dermatological complications such as the ones here mentioned, and many other medical areas. Don’t hesitate and start using it now! Veterinarians, pets and pet owners will not believe the speed of the results!