Bovine Amnion Hastens Wound Healing? Julie Bell

CASE NARRATIVE

BOVINE AMNION HASTENS WOUND HEALING?

Julie Bell

Southern Rangitikei Veterinary Services julie@srvs.co.nz

On July 14, 2021, a TB yearling was found in the paddock with a large wound on his dorsolateral forearm just above the carpus. The yearling had been checked 24hrs previously and the state of the wound tissues indicated that the injury had occurred soon after that check.

Upon inspection, the wound was very deep, transecting the common digital extensor as well as various other soft tissues in the area. The yearling was unwilling to move but was able to mobilise the limb with mild knuckling when forced to move and was able to bear some weight on the limb at rest. The carpus joint did not appear to be involved. The wound was cleaned, flushed, debrided, and bandaged and the yearling was placed on gentamicin, penicillin and phenylbutazone at standard dose rates; the patient had been recently given a tetanus booster vaccine. Due to budget constraints and knowledgeable owners the yearling was left for the owners to medicate over the weekend.

The yearling improved over the weekend and the following week. As expected, further debriding was performed on the second visit after more soft tissue died away. When revisited the following week it was clear that the stump where the tendon was transected was not granulating in, likely due to constant movement of the region. There was an area above the stump that needed additional debridement but was granulating sufficiently.

It was at this point that it became evident that further intervention may be needed for this wound to heal. The goal was to help bring extra nutrients to the area to increase healing yet still stay within the budget constraints of the clients. Articles about the use of equine amnion as a biological dressing in equines sounded promising. As it was not foaling season this did not seem that practical but since the owners (dairy farmers) had just begun calving it was decided that it was worth trying bovine amnion instead. Annette McCoy’s 2017 AAEP presentation on amnion as a wound dressing was extremely helpful. In this short presentation she describes two very simple methods of preparing the amnion. The owners were willing to give it a go and collected the cleanest, freshest, bovine amnion they could find - within 1hr of calving - and dropped it into the clinic. There were two methods of processing described by McCoy (2017) but the Iodine method of preparation, as shown in text box, was more suitable due to individual time restrictions.

IODINE/ACETIC ACID PROTOCOL

1. Cut off areas with ground-in debris and rinse the amnion with gentle agitation under cool tap water to remove gross debris. 2. Cut the amnion into multiple pieces depending upon the size of dressings needed. Note that the protocol does this after processing, but it was easier to work with smaller pieces. 3. Place amnion in a 2% povidone iodine solution, gently agitate and refrigerate for 24 hours. Saline bottles were ideal for making the solution and then storage. 4. After 24 hours refrigeration, rinse the amnion 3 times in sterile saline and once in 0.25% acetic acid (regular vinegar diluted down) 5. Refrigerate the dressings in 0.25% acetic acid until use (up to one year).

The amnion was placed under the bandage and the bandage was changed every 7 days or as needed with a new amnion dressing placed each time. The owners did this themselves unless a vet was already present on the farm for another case. The wound made significant improvements over this time as seen in the photos. The area that contained the tendon stump began to form a much healthier tissue bed and granulated into the area above it. Photos of the progress are shown below. As with any injury it is impossible to know if the amnion treatment had any effect on the progress or if the amnion was placed coincidentally at the time that the wound was about to produce more healthy tissue and significantly improve itself. It is to be noted that this wound was on the upper limb which does tend to heal better than the distal limb. However, the treatment was cheap and easy and definitely did no harm. It also left a very positive impact with the owners.

Amnion has been used on wounds since as far back as the 1900’s in both human and veterinary medicine. Amnion tissue contains many biological molecules and growth factors that are beneficial to wounds by promoting tissue growth and healing. It is also recruits the body’s own stem cells to the wound. It is thought to be especially helpful in contraction of chronic wounds for this reason. Equine amnion in comparison

Figure 1: Progress in wound healing by days from initial injury. A, 14 days - the wound had been debrided 2 days previously; B, 19 days - the day before amnion treatment began and the last time the wound needed debridement. C, 31 days; D, 66 days – about 2 months from initial injury, the patient being sound and the wound healing well.

to other species is particularly useful as a wound dressing due to a thicker connective tissue layer and, if the timing fits, is potentially a better choice than bovine amnion.

As outlined above the iodine/acetic acid protocol was used in this case but there is also a dilute chlorhexidine protocol that can be followed. Both are simple and require no expensive equipment. Following the protocol is important to reduce the likelihood of introducing a pathogenic bacteria to the wound but also to preserve the protein content within the amnion. Using hot water or harsher antiseptics can disrupt this protein and reduce the efficacy and wound healing benefits of the dressing. Studies on both the reduction of bacteria following processing and the integrity of proteins and structure following processing and storage have been done on more than one occasion. It is hard to base a lot of belief on the results of one case. However as mentioned above the dressing was cheap and easy to use. The owners were very positive about the process and the wound appeared to make significant improvement coinciding with the start of the amnion dressing application. It would be interesting to use this treatment again in the future, especially on some challenging chronic distal wound cases that often prove to be challenging and frustrating.

Reference

McCoy AM. How to Prepare and Store Equine Amnion for Use as a Biological Wound Dressing. Proc AAEP Ann Conv 2017; 63: 200-2005. Audio available at https://aaep.digitellinc. com/aaep/sessions/1878/view with registration; accessed 04_11_2021.

KESTER NEWS HOUR AAEP 2021 VIRTUAL ISSUE

https://beva.onlinelibrary.wiley.com/doi/toc/10.1001/(ISSN)2042-3306.Kester.News.Hour.and.Milne.Lecture.AAEP.2021

These papers from EVJ and EVE were discussed at the Kester News Hour during the Annual Convention of the American Association of Equine Practitioners, December 2021 and are available HERE as Open Access or Free-To-Read papers • Radiological prevalence of osteoarthritis of the cervical region in 104 performing Warmblood jumpers.

Espinosa-Mur P et al. • Caudal cervical vertebral morphological variation is not associated with clinical signs in Warmblood horses. S.

Veraa et al. • Factors associated with survival and racing performance of 114 Thoroughbred foals with septic arthritis compared with maternal siblings (2009-2015).

O’Brien TJ et al • Detection of synovial sepsis in horses using enzymes as biomarker. Haralambus R et al. • Active immunisation against GnRH as treatment for unilateral granulosa theca cell tumour in mares. Behrendt D et al. • Deep digital flexor tendon lesions in the pastern are associated with the presence of distal tendinopathy. Acutt EV et al. • Current joint therapy usage in equine practice: Changes in the last 10 years. Zanotto GM and Frisbie DD.

NZ EQUINE RESEARCH FOUNDATION

As many of you are aware the NZ Equine Research Foundation Inc (NZERF) was established in 1977 to foster education of and research for the NZ Horse Industry. In 1981 the NZERF was registered as a Charitable Trust.

Over the years NZERF has funded many research projects and has promoted and expanded public knowledge by conducting seminars, releasing videos and publishing bulletins and booklets. Several Scholarships are also available, two of which are specifically available to Veterinarians. The Jonathan Hope Equine Veterinarian Scholarship is available to help ‘young at heart’ equine practitioners travel, either nationally or internationally, to ‘see practice’ and improve their practical skills whilst the Veterinarian/Farrier Scholarships are available for Vets & Farriers from the same geographical area to spend time at a suitable course and/or with colleagues in a suitable practice.

The NZERF Board is made up of nominees or co-opted members of the racing codes, breeder organisations, equestrian sport and pony clubs, and Massey University. In addition, we have had strong support and participation from NZEVA and Veterinarians in Equine practices.

Covid has had some impact on NZERF activities with the popular Lecture series being on hold and Scholarship winners not being able to travel overseas.

We appreciate the assistance that practitioners provide by making their clients aware of our publications and having copies available to pass on to them. To facilitate this, we send supplies to several practices. If you have not received copies of our bulletins or require additional copies, please contact our office: nzerf@xtra.co.nz or 021 555 954. Details of booklets still available will be set out on our website when it is updated in the next little while. There is no charge for the publications but as a Charitable Trust we welcome donations.

We are attempting to build up a library of short videos. These are most suitable for client evenings.

Please continue to promote NZERF activities and its publications to colleagues and clients. Doing so will promote better knowledge of the horse.

If you require any clarification on any activities of NZERF please do not hesitate to make contact.

Tim Pearce

Chairperson NZERF timpearce@srvs.co.nz

BRIAN GOULDEN AWARD New Zealand Equine Veterinary Association

The Brian Goulden Perpetual Trophy will be awarded annually and presented at the Annual Dinner of the NZEVA conference. This annual prestigious prize is awarded to members or past members of the NZEVA who have shown leadership, enterprise, contribution to knowledge or education, and have made significant contributions to the equine veterinary profession in New Zealand. Please send your nomination including name, address and qualifications, together with any supporting information for the nominee, whom the nominator considers merits the award. This can include curriculum vitae, letters of support and documentation of achievements etc. Send all details AT ANT TIME to nzevasecretary@gmail.com. Brendon Bell NZEVA President

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