Wound debridement is the most important first step in wound management and will significantly affect the end result for the patient. In heavily contaminated military wounds this is often only achieved with several stages. The first debridement is performed within the constraints of ‘Damage Control Surgery’, and should be as thorough as possible without being excessive. Marginal debridement, where all necrotic tissue is removed but where injured and potentially viable tissue is retained, is an appropriate level of debridement at the first operation. Prior to wound debridement all wounds should be cleaned of particulate matter using soap and water. A tourniquet should be applied if possible.
Digital photography now allows for many images to be taken at very low cost. Such photographs are a useful reminder of how the wound looked, can be referred to at each dressing change, and are particularly useful when trying to convey the details of the wound to another practitioner.
The MolecuLight i:X Imaging Device is a portable, non-invasive, real-time camera used to visualise and quantify the bacterial load in a wound. It uses violet light to capture the fluorescence of endogenous structures in the connective tissue matrix as well as harmful bacteria. The MolecuLight i:X captures pictures of wounds and illuminates potentially detrimental levels of bacteria.
We have found that NPWT, when used in combination with comprehensive surgical assessment, exploration, and meticulous debridement, greatly facilitates wound management. It also stabilizes the soft tissues, salvages compromised tissue, reduces oedema, the number and frequency of dressing changes, and facilitates further reconstructive surgery.
Take home messages:
1. Marginal debridement, where all necrotic tissue is removed but where injured and potentially viable tissue is retained should be performed at the first operation.
2. NPWT allows for wound isolation and exudate management
3. The moleculight camera provides guidance for clinicians in regards to the following: highlighting bacteria, identifying the type of bacteria to be treated and pinpointing the location of the colonisation for more accurate swabbing.
Professor John Williams
MA VetMB LLB CertVR DipECVS FRCVS
Vets Now 24/7 Hospital Manchester
'And today’s challenge...!'
The prognosis for dogs and cats with penetrating body cavity wounds is largely dictated by the severity of any concurrent injuries. Bite wounds are the commonest cause of penetrating body wall injury in the dog and cat. Though other injuries are seen such as gunshot wounds, stick injuries, knife wounds etc. It is important to remember that the external wound is often, the “tip of the iceberg” as there is potential for severe underlying tissue and organ injury. Ultrasound and CT of thoracic or abdominal wounds can be used to determine body cavity penetration, but surgical exploration of these wounds is essential.
There are a number of retrospective veterinary studies on penetrating wounds, these include gunshot wounds, bite wounds and oropharyngeal stick injuries. All the literature is retrospective and no hard and fast guidelines are given for the timing of surgical intervention.
What do we know?
One of the issues we have is that the extent of any penetrating injury is dependent on the inflicting object e.g. high velocity gun shot wounds will have a different consequence compared with a bite wound. In one series of 16 cases of body cavity penetration, 14 survived and of the two that died one was due to a bite wound and the other a gunshot injury (1). A retrospective paper looking at thoracic bite wounds in 65 cases and had an overall survival rate of 84.6% (2), which is in line with an earlier paper which had a survival rate of 80% (3). The paper by Ateca and others4 report the complications associated with bite wounds and they concluded that prolonged anaesthesia, development of SIRS or multi-organ failure significantly increased the risk of mortality. The largest study on dog bite wounds looked at 196 cases and had an overall survival of 93%, the dogs that died all had thoracic or abdominal trauma; surgery, including thoracic exploration, by their analysis did not affect mortality rate in these patients (5). These survival rates for traumatic bite wounds are borne out by a recent paper on 15 (4) Coyote attack on dogs (6), though this data is confounded by cases being euthanized on financial rather than absolute clinical grounds.
High velocity bullet injuries carry a poor prognosis, though they are fortunately rare, one paper which looked at military dogs only had a 38% survival rate (11 of 29 dogs) (7).
What should we do?
Ateca and colleagues4 in their detailed analysis of extensive bite wound cases concluded that those patients where there was a long time from admission to anaesthesia had prolonged hospitalisation time. This reflected the severity of injury at the time of presentation and the likelihood that it took longer to stabilise these cases., these patients were also more likely to develop wound infections.
The study by Risselada and others (1) recommends that all cases where there is abdominal or thoracic penetrating trauma should undergo surgical exploration, due to the high probability of there being internal organ trauma. But they do not give an indication as to when surgery is best carried out.
The importance of a thorough clinical examination and diagnostic work up cannot be over emphasised in these cases. Thoracic and abdominal radiographs are useful adjuncts, but radiological features are not be enough on their own to determine if surgical exploration is needed (3). It is therefore argued that where there is thoracic or abdominal penetration and trauma, that surgical exploration is always warranted. Each case is different and has to be assessed as an individual, timing for intervention has to be based on severity of initial trauma and the ability to stabilise the patient.
Currently AFAST does not have the necessary sensitivity to be recommend it as a first line diagnostic tool for canine penetrating wounds, but it may prove an useful adjunct to radiography and clinical examination (8). TFAST has a high specificity and sensitivity for penetrating thoracic trauma9; it is an excellent modality to diagnose pneumothorax, rib fractures, intercostal muscle tears, diaphragmatic hernia, haemothorax, haemopericardium, and other potentially life threating injuries.
Initial analgesia is clearly mandatory in all cases. As noted above the issue with bite wounds is that the external wound is the ‘tip of the iceberg’; wound lavage with Hartmann’s’ solution should be carried out initially with the patient anaesthetised once stabilised. Surgical exploration is then carried out as it has been associated with more likely survival to discharge (6,10). The use of antibiotics in these cases has been debated; their use is currently seen as a positive potential predictor of outcome6. It is known that in most dog bite wounds there are at least (5) different bacterial isolates per wound (usually (3) aerobes and (2) anaerobes). The Common gram-negative aerobes from dogs include Pasteurella spp., and Enterobacter cloaceae, and common gram-positive organisms include Streptococcus and Staphylococcus spp., Corynebacterium spp. and Enterococcus faecalis. Common anaerobic isolates include Porphyromonas spp., Propionobacterium spp., Bacteriodes spp., Eubacterium spp., Fusobacterium spp., and Peptostreptococcus spp.(11). Co-amoxiclav is the recognized empirical treatment of choice for bite wounds, initially intravenously at 22-25mg/kg
Cases with penetrating bite wounds should be stabilised, examined thoroughly and undergo radiographic and TFAST examination. Wounds should be flushed and explored if there is suspicion of penetration into the abdominal or thoracic cavities.
1. Risselada M, de Rooster H, Taeymans O, van Bree H. Penetrating injuries in dogs and cats. Veterinary and Comparative Orthopaedics and Traumatology. 2008. doi:10.3415/VCOT-07-02-0019.
2. Cabon Q, Deroy C, Ferrand F-X, et al. Thoracic bite trauma in dogs and cats: a retrospective study of 65 cases. Veterinary and Comparative Orthopaedics and Traumatology. 2015;28(6):448-454. doi:10.3415/VCOT-15-01-0001.
3. Scheepens ETF, Peeters ME, L’Eplattenier HF, Kirpensteijn J. Thoracic bite trauma in dogs: a comparison of clinical and radiological parameters with surgical results. J Small Anim Pract. 2006;47(12):721-726. doi:10.1111/j.1748-5827.2006.00114.x.
4. Ateca LB, Drobatz KJ, King LG. Organ dysfunction and mortality risk factors in severe canine bite wound trauma. Journal of Veterinary Emergency and Critical Care. 2014;24(6):705-714. doi:10.1111/vec.12256.
5. Shamir MH, LEISNER S, KLEMENT E, GONEN E, Johnston DE. Dog Bite Wounds in Dogs and Cats: a Retrospective Study of 196 Cases. Journal of Veterinary Medicine Series A. 2002;49(2):107-112. doi:10.1046/j.1439-0442.2002.jv416.x.
6. Frauenthal VM, Bergman P, Murtaugh RJ. Retrospective evaluation of coyote attacks in dogs: 154 cases (1997-2012). Journal of Veterinary Emergency and Critical Care. 2017;27(3):333-341. doi:10.1111/vec.12601.
7. Baker JL, Havas KA, Miller LA, Lacy WA, Schlanser J. Gunshot wounds in military working dogs in Operation Enduring Freedom and Operation Iraqi Freedom: 29 cases (2003-2009). Journal of Veterinary Emergency and Critical Care. 2013;23(1):47-52. doi:10.1111/j.1476-4431.2012.00823.x.
8. Lisciandro GR. Abdominal and thoracic focused assessment with sonography for trauma, triage, and monitoring in small animals. Journal of Veterinary Emergency and Critical Care. 2011;21(2):104-122. doi:10.1111/j.1476-4431.2011.00626.x.
9. Lisciandro GR, Lagutchik MS, Mann KA, et al. Evaluation of a thoracic focused assessment with sonography for trauma (TFAST) protocol to detect pneumothorax and concurrent thoracic injury in 145 traumatized dogs. Journal of Veterinary Emergency and Critical Care. 2008;18(3):258-269. doi:10.1111/j.1476-4431.2008.00312.x.
10. Hall KE, Holowaychuk MK, Sharp CR, Reineke E. Multicenter prospective evaluation of dogs with trauma. Journal of the American Veterinary Medical Association. 2014;244(3):300-308. doi:10.2460/javma.244.3.300.
11. Talan DA, Citron DM, Abrahamian FM, Moran GJ, Goldstein EJC. Bacteriologic Analysis of Infected Dog and Cat Bites. http://dxdoiorgliverpoolidmoclcorg/101056/NEJM199901143400202. 2008;340(2):85-92. doi:10.1056/NEJM199901143400202.
Principles of reconstruction
Reconstructive surgery is used to reduce tension during wound closure. It is important to understand the principles that inform the surgical techniques, and in particular the differences between skin grafts, random pattern flaps and axial pattern flaps, so a sensible choice can be made between them.
Take home messages:
Open wound management is good for some cases but a poor choice for others
The causes of failure of wound closure delayed decision making and a poor choice of closure technique.
Sound surgical planning will reduce the risk of failure
MBA BSc(Hons) VTS(Anesthesia/Analgesia & ECC) DipAVN(Medical&Surgical)
RVN Clinical Support Manager, VetsNow, Manchester
Just in Case it’s Infected...
Whenever prescribing antibiotics, ideally their selection should be based on results of culture and MIC susceptibility. The minimum inhibitory concentration (MIC) is the concentration of a particular antibiotic that prevents visible growth of the bacteria in question after incubation for up to 18 hours. Bacteria are considered to be susceptible if growth is inhibited with ½ the average clinically obtainable blood concentration of the drug (or ¼ peak plasma concentration). In cases where antibiotics must be administered before culture results are obtained &/or are given empirically, it is imperative to identify the following:
1) if the patient has a treatable microbial infection;
2) location of infection;
3) identification of most likely pathogens;
4) identification of antibiotics most likely to be effective;
5) determining the appropriate route of administration; and
6) determining treatment length.
If at all possible a sample of the infected material should be obtained and gram stained. This will give a minimum database of information to guide antibiotic selection. Then the antibiotic should be selected based on the knowledge of the most likely pathogen present ant usual antibiotic susceptibility patterns.
It is important to be aware of risks associated with antibiotic use, other than bacterial resistance or antibiotic failures. Antibiotics may interfere with normal bacterial flora ('healthy bacteria') which can give pathogens an advantage. Known toxic effects of antibiotics should also be evaluated in the selection of antibiotic choice. Sulfonamides are known to cause or trigger allergic reactions, keratoconjunctivitis sicca (dry eye), hepatitis, and immune mediated blood dyscrasias. Aminoglycosides have a dose related renal toxicity and patients must be monitored closely.
Antibiotic resistance can develop in most bacterial lines by one of two mechanisms, being either chromosomal or plasmid mediated. Chromosomal mutations are rare but the frequency of these mutations increases by antibiotic use and antibiotic concentration at the infection site. If antibiotics are improperly dosed or given for inappropriate lengths of time then conditions favorable for these chromosomal mutations are provided. Underdosing antibiotics in either fashion kills off the susceptible bacteria and leaves the resistant ones intact, offering them a survival advantage. These resistant bacterial strains, usually present in low numbers, can now propagate freely, creating a stronger, more resistant strain. Plasmid mediated resistance is very common. Plasmids are extrachromosomal circular pieces of DNA that function independently within the bacteria. Bacteria will exchange these plasmids freely, even between different bacterial species. Plasmids can contain coding for drug resistances and one plasmid can contain encoding to a number of different antibiotics, thereby passing the resistance of one bacterial type to another bacteria. They can also contain the information for production of a variety of β-lactamases, which are enzymes that can inactivate the β-lactam ring containing antibiotics. Gram-positive bacteria can secrete these β-lactamases extracellularly and can thereby inactivate antibiotics in the immediate environment.
Gram-negative bacteria secrete and store concentrated doses of β-lactamases in the periplasmic space which is the site of action for β-lactam antibiotics.
1. Clinicians should understand the concept of bacterial sensitivity.
2. The action of different antibiotics should be understood and are important considerations.
3. Avoidance of antibiotic resistance is critical in the modern clinical setting.
In dogs, most elbow wounds result from wound breakdown following surgical removal of a cutaneous or subcutaneous mass, such as a soft tissue sarcoma, mast cell tumour or hygroma. Surgery should be avoided in this area unless essential and other options for treatment should be explored. Owners should be warned of the possible complication of wound dehiscence and that if this occurs, it is likely to require further surgery to resolve.
In cats, axillary collar wounds are the most frequent challenge, often becoming chronic and failing to heal. An important recent observation made by Brinkley, was that in cats, the olecranon is freely mobile beneath the skin of the axilla, rather than attached to the olecranon/triceps as is the case in dogs. This resulted in the idea of recreating the elbow fold in cats with axillary wounds. This method recreates normal anatomy and as such is associated with a high degree of success, even in inexperienced hands and the author considers this to be the current treatment of choice for this condition.
Take home messages:
1. Wound healing on the elbow or in the axillae of dogs and cats is often challenging due to excessive motion, friction, tension and repetitive trauma.
2. Explore all possible options and seek advice PRIOR to removing masses from the elbow region of dogs. Reconstruction here can be challenging!
3.Understanding the relationship between the skin and underlying muscle/bone in the axilla is key to successful surgery in this area. Cats are NOT small dogs!
Brinkley C.H. (2007) Successful closure of feline axillary wounds by reconstruction of the elbow skin fold. Journal of Small Animal Practice. 48: 111-115
Mrs Elisa Best
BVSc Cert SAS MRCVS
Rowe Referrals, Bristol
Negative pressure wound therapy - can it work for you?
Negative pressure wound therapy is a closed system of open wound management that has many uses in veterinary practice including the treatment of open wounds, treatment of surgical wound break down, augmentation of skin grafts and prevention of complications in high risk incisions.
Mechanism of action involves reduction of interstitial oedema, angiogenesis, removal of exudate and increased blood flow to the area.
Take home messages:
1. Application of NPWT requires at least 2cm of healthy intact skin surrounding the wound.
2. Overnight care is essential as the NPWT can not be disrupted for more than 2 hours before complications occur.
3. NPWT dressings are normally changed under sedation at intervals of 48-72hrs, although over intact skin and skin grafts it can be left on much longer (7 days in skin grafts) in which case a non adherent silicone layer should be applied between the foam and the skin to prevent damage.
Negative Pressure Wound Therapy; Stanley, Bryden J.. In Wound Management, Veterinary Clinics of North America: Small Animal Practice. November 2017 47(6):1203-1220
Current Concepts in Negtaive Pressure Wound therapy.Howe, Lisa M.. In Soft Tissue Surgery, Veterinary Clinics of North America: Small Animal Practice. May 2015 45(3):565-584
Dr. Dylan Gorvy
BSc BVSc CertES (Soft Tissue) PhD Dipl. ECVS
Mälaren Horse Clinic, Sweden
Wound bed preparation for primary closure
Horses often sustain traumatic wounds, commonly associated with tissue loss, necrosis and heavy contamination. Whenever possible, primary closure is preferred over healing by second intention. This reduces the risk of further wound contamination and infection and, if successful, healing is faster, with a better cosmetic and functional outcome.
Effective debridement is essential in order to minimise the risk of dehiscence following primary closure. Traditional wound debridement involves sterile saline irrigation and sharp resection. However, this is time-consuming, laborious, and inefficient. A more effective, hydrosurgical device (VersajetTM) has became available during the last decade and is widely used in the human field to manage burns and a variety of other wounds. This has been shown in in-vitro to be more effective than traditional debridement methods (Skärlina et al. 2015). In addition, in my experience hydrosurgical debridement enables the primary closure of wounds that would otherwise be left to heal by second intention.
Take home messages:
1. Almost all equine wounds can be closed primarily, provided the wound bed is prepared effectively
2. Infection is an important cause of wound dehiscence
3. Hydrosurgical debridement is far more effective than traditional methods, and allows the primary closure of wounds that would otherwise be left to heal by secondary intention.
Skärlina EM1, Wilmink JM, Fall N, Gorvy DA. Effectiveness of conventional and hydrosurgical debridement methods in reducing Staphylococcus aureus inoculation of equine muscle in vitro. EVJ 2015 Mar;47(2)
1) Direct debridement through the production of collagenases
2) An antibacterial effect through ingestion and the production of a potent bactericide
3) They are thought to stimulate wound healing through increased wound oxygenation and an increase in wound pH
In people, maggots are regularly used for pressure ulcers, malignant wounds, diabetic ulcers, and multiresistant infections such as MRSA. In horses, maggot debridement therapy has been described for the management of hoof infections, septic navicular bursitis, fistulous withers, and other chronic resistant infections.
As antibiotic resistance increases, and we head towards a post-antibiotic era, maggot therapy should no longer seen as a last-resort therapy.
Dr. Dylan Gorvy
BSc BVSc CertES (Soft Tissue) PhD Dipl. ECVS
Mälaren Horse Clinic, Sweden
Making it Stretch; Tension relief, skin mobilisation, and expansion
The overall goal in the management of any wound is to achieve a result that is as functional and cosmetically appealing as possible. Primary closure, delayed primary closure (before the appearance of granulation tissue) and secondary closure (after the appearance of granulation tissue) can be challenging in the horse as the result of skin loss or excessive tension due to anatomic location. Carefully planned tension relief, skin mobilising, and skin expansion techniques can be used to help close these wounds and therefore minimise the functional shortcomings of excessive scarring. This must be combined with adequate immobilisation, where possible, in order to maximise the chance of success.
Take home messages:
1. Primary closure, where possible, should be the goal in almost all traumatic wounds
2. Understanding the principles and limitations of tension relief, skin mobilisation, and skin expansion can help to close challenging equine wounds
3. Immobilisation, where feasible, is essential for a successful outcome
Dr. Patrick Pollock
BVMS, PhD, CertES(Soft Tissue), DipECVS, FHEA, FRCVS
Dick Vet Equine Hospital, University of Edinburgh
Grafting and Reconstruction
In some cases the use of skin grafts is the most economically viable and welfare friendly option for the wounds of horses. While there are a variety of techniques, a number of them are particularly applicable in the field. Careful discussion with the horse owner is important and making an early decision to graft can often be challenging. The following session will outline a number of reconstruction and grafting techniques
Casting and Bandaging
A great many options are available when selecting dressings for use in horses. If possible basic principles and an evidence based approach should guide the clinician. Careful attention to the stage of healing, identification of impediments to healing and long term goals is important.
Casting is an underused but very useful technique.
An evidence based approach to selection of wound dressings will be presented including techniques and uses for casts
Take home messages:
1. Clinicians need to recognise the stages of wound healing and which technique is appropriate for different wound
2. All wounds be assessed to identify anatomical structures involved and to establish any of the '12' factors may delay healing. (Knottenbelt 2007)
3. A management plan should be prepared for EVERY wound including appropriate dressing selection.