Victorian Bushfires 2009

Transcription

1 Victorian Bushfires 2009 OVERVIEW On the 7 th February, 2009, some of the worst fires in the state s history ravaged through Victoria. Around the areas of Kilmore, Wandong, Kinglake, Strathewen, St. Andrews & the Yarra Valley, the death rate to humans and animals was horrendous. Surprisingly though, for the very large equine population residing in these areas, losses were lower than what most people expected (one of the official figures for the state of Victoria was 132). Our clinical impression was that approximately 10-20% of the general equine population had some degree of injury, being mainly burns or physical injuries, attributed to the bushfires. The horses flight response appears to have saved many of our equine friends. Our clinics examined approximately 160 affected horses. Burns (largely due to radiant heat) ranged from superficial to full thickness and largely involved faces, lower limbs, pectoral region & axillae, and perineal & inguinal regions. Systemic and other organ effects were surprisingly minimal, though many horses showed some generally minor respiratory effects. The main lessons we learnt regarding bushfire effects on horses include: The flight response of horses is protective in coping with bushfires. Horses left in large paddocks with low pasture and vegetation cope best. Ultimate severity of burns is unpredictable from initial presentation, and may not be apparent until up to eight weeks later. Compared with stable fires, respiratory effects are minimal. Even with extensive full thickness burns, secondary effects including infection, dehydration and renal failure are relatively uncommon. Basic principles of wound management applied to burns yields good results. Severe coronary band damage is generally reversible. Following are our experiences with some of the injuries we dealt with as a result of the bushfires. FACIAL INJURIES These photos are typical of the facial burns we treated. Some horses had extensive matting of the eyelashes with a grey sludge material (suspected ash / charcoal / serum / tears), while others lost their muzzle hairs and

2 eyelashes. Though a few minor ulceration and conjunctivitis cases were noted, we observed no other direct ophthalmic injuries. Facial burns showed an interesting consistently familiar pattern; generally superficial to partial thickness burns of the muzzle, cheeks (facial crests) and periorbital regions. Non pigmented regions suffered greater scarring. A particular concern is the effect of cicatrization on eyelid function. PERINEUM / INNER THIGHS Many of the horses treated had burnt tails, ranging from hair singeing and matting to partial thickness skin burns. Some had burnt patches of skin on the flanks and / or thoracic area, attributed to a burning tail, which had been flicked onto the side of the horse. Vulvas, prepucial sheaths and udders were commonly burnt along with the skin of the perineum and inguinal regions. Generally, our impression was that the fillies and mares suffered more burn wounds to vulvas and udders than their male counterparts did to their sheaths, but this may only be a reflection of the population of horses in the areas.. LOWER LIMBS Many lower limbs were affected with superficial to full thickness burns. Generally the limbs were oedematous on presentation. Some had a dark charcoal grey exudate (similar to that noticed on the matted eyelids) from their skin, which continued to exude for up to eight weeks. It was interesting to note that the exudate was very similar in colour regardless of the environment in which they were housed (dirt yard, sand yard or a grass paddock). Associated with many lower limb burns was circumferential hoof wall separation at the coronet, in some cases resulting in moderate to severe laxity of hoof walls. A few cases of full thickness burns eventually (up to 8 weeks later), resulted in open synovial structures. HOOF REPAIR It has generally been thought that extensive coronary band damage is a poor prognostic sign. However, that was not our experience with the bushfire victims. We observed extensive coronary band separation in many cases, and two cases of apparently full coronary band sloughs of all feet (also observed in many cattle). Many showed significant hoof wall instability. Though some of these cases suffered severe foot pain, all cases remained mobile and re-grew normal, healthy hoof walls.

3 SMOKE INHALATION Burns were not the only injuries requiring veterinary intervention during the fires. Some horses presented with marked respiratory distress as a result of smoke inhalation and / or respiratory mucosal heat damage, even though visually they had little or no skin involvement. Of the horses requiring some form of treatment approximately 80% showed some respiratory involvement but of these only 20% required specific treatment for respiratory disease. Bonnie was presented in severe respiratory distress several days after the fire and could not work more than 3 strides without marked coughing spasms. Auscultation revealed significant wheezing noises on both sides of the chest but ultrasound examination did not show any pleural fluid. Initially she was treated with procaine penicillin, gentamycin and clenbuterol. Metronidazole was commenced approximately 4 days later due to non response to the initial treatment. Due to Bonnie s growing intolerance of procaine penicillin injections, following 2 weeks of penicillin / gentamycin / metronidazole / clenbuterol she was changed onto trimethoprim-sulfadiazine / metronidazole / clenbuterol. She was treated for a period of 6 weeks in total. Bonnie is still clinically very bright, and has not been heard to cough although there was still some audible wheezing on her chest when last auscultated. PUZZLES; A CASE STUDY 'Puzzles' was brought to our clinic 18 hrs. after the firefront went through, with moderate limb & facial swelling, but was reasonably bright. He was initially managed with flunixin meglumine, procaine penicillin, limb bandaging, and topical creams. Over the first week, swelling became extensive, and the skin of most of the limbs, the ventral head, pectoral region, axillary, groin, sheath and perineal areas developed eschar and sloughed. He was very reluctant to move, though maintained a positive appetite, and his pain was managed via NSAID's, opioids, a ketamine CRI and epidurals. Hydration was managed via oral fluids. Antibiotics and NSAID's (with ranitidine hydrchloride) continued. Bloods at this stage showed???? At 5 days, coronary band separation and hoof wall instability was obvious. He required sedation including narcotics to bathe, medicate & bandage the necrosing areas daily. Over the next month, his mobility & comfort gradually improved. Daily wound care & bandaging was very time consuming and would have proved extremely expensive if not for donated products & services. Over this time, gradual necrosis & breakdown of successive layers of tissue

4 occurred. The face did not show the same degree of tissue sloughing, but was quicker to cicatrize. By 6-8 weeks, the tissue breakdown was so extensive as to create exposed lower limb ligaments & tendons, fetlock joint exposure & extremely deep muscle fissures. The loss of integrity of a hind DDFT was managed with a heel extension / elevation shoe, his joint exposure was treated aggressively as an open splinted wound, and the huge fissures were managed with frequent flushing and fly repellants. Lower limb granulation tissue was difficult to control despite daily bathing & bandaging, antibacterial creams, manual resection, astringents and cortisone cream. Despite the extensive damage to tissues in the region of the sheath & anus, he never had difficulty urinating or defaecating. Sadly, Puzzles was euthanased 3 months after the fires. In the last month he gradually lost his bright demeanour, and pain control became more difficult. Individually, we considered each injury recoverable, however the sum of multiple injuries and mobility problems associated with wound contraction and scarring became unmanageable. TRAUMA There were a number of horses with lacerations to their limbs, face and other regions of their bodies as a result of either flying debris or running into or through fences: these were treated routinely. WOUND MANAGEMENT Initially, burnt areas presented with redness, swelling and pain. In the more severe cases, the swelling & pain became worse over a number of days, and was accompanied by the skin becoming cold, eschar formation and sloughing (including the

5 coronary band.) The less severe cases tended to have some form of exudation, not always accompanied by skin loss. We managed the burnt areas with saline & iodine/chlorhexidine bathing & flushing, non stick dressings and bandaging where possible, and antibacterial creams such as Silvazine. Pain was managed by NSAID s (sometimes with ranitidine hydrochoride), opiods, and where necessary ketamine CRI and epidurals. Sedation (including opiods), was sometimes necessary in the first few days to bath, treat and bandage these wounds due to the pain involved. Effected horses were kept on antibiotics as long as necrosis was active. In severe cases, gradual necrosis and breakdown of successive layers of tissues continued for up to eight weeks, including a tendon & joint capsule slough. A heel extension/elevated shoe assisted with the DDFT breakdown in the hindlimb, and a splint was used to help with healing of an open fetlock joint. Huge muscle fissures were managed with flushing and fly repellents. Extensive granulation tissue formation in the lower limbs was difficult to control, despite frequent bathing & bandaging, antibiotics and antibacterials, manual resection, astringents and cortisone cream.