9 minute read
BUSINESS
Luke Annetts
Growing up in a rural area, Luke has always had a passion for animals and for helping people to help their pets. His passion is providing the best of carefor all animals, despite working in rural areas and despite the lack of readily available emergency practices. Annetts graduated from Murdoch University, Perth, in 2009 and has spent time working in mixed practice in Bundaberg, prior to purchasing the Tenterfield Veterinary Clinic. He aims to provide an essential service to a rural area, without compromising quality of care, while ensuring only the best products make it onto practice shelves.
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Snake bites: a rural mixed-practice perspective
AtTenterfield Veterinary Clinic we are a small (three full-time veterinarians) rural veterinary practice, with the nearest emergency centre more than three hours away.
Generally, we treat 10–20 snake bite cases per season (August to March), mainly in dogs, though there are some cats and the occasional horse. Despite being a small clinic, we carry five vials of antivenom at any one time, after experiencing several incidents where we had to treat three differentdogs (often Jack Russells and often from the same family) within asingle 24-hour period.
With fast diagnosis and appropriate treatment our success rate is very high, finances permitting. Most of the dogs we see present with typical signs of collapse, and/or vomiting, and/or paralysis. If we are lucky –unlucky for the animal and client –the owner has found their pet playing with a dead or live snake. We confirm our diagnosis either byhistory(if the client has seen the animal with the snake) and clinical signs, or by a combination of history, clinical signs, coagulation testing (generally PT/APTT) and CK (generally peaks 4-12 hours after insult) and urine dipstick.
Once our suspicions are confirmed, we progress to administration of snake antivenom via a syringe pump, generally over 10minutes. Summerland Serums’ Tiger/Brown Multi is the only antivenom we stock, and it has been my trusted product since graduation.
Years ago, I used to pre-med my snake antivenom cases with corticosteroids and antihistamines, but I stopped doing this seven or eight years ago and have not noted any ill effects. In fact, we very rarely
note any reaction with the administration of Summerland’s antivenom, with only the veryodd minor issue – minor swelling around the face or a slight elevation in heart rate – which resolves soon after.
In our experience the sooner the venom can be neutralised in the patient’s bloodstream the better. This sometimes necessitates the use of two to three vials of antivenom. Although there is an added cost, this can be the difference between a healthy patient the following day or one requiring days in hospital with expensive and labour-intensive supportive care, not to mention potential death. Weoften perform serial clotting tests to monitor the response to treatment and find great success with our trusted antivenom.
Over the years I have had many success stories and will share a few here. Out of desperation – in rural remote practice years ago –the only antivenom available was an out-ofdate bottle of Summerland’s serum. It worked and an animal was saved. (Obviously I would never advocate this, and thankfully the veterinary profession has moved beyond leaving vets, patients, and clients in similarly compromising positions since then).
Another, such story was when Iwas looking after my brother’s four-month-old Jack Russell pup. The dog was helping me fill up water troughs during the drought. She vomited once, so I put her in the car, thinking she must be just hot, and proceeded to continue.
A little while later she had another vomit, so I took her inside and left her with my brother. After much more time had passed my brother asked me a few times if I was sure the pup was ok, and reassured him it was fine. Eventually, my brother To page 30
Are keel bone fractures a growing problem for the layer-hen industry?
Discusses the skeletal health of layer hens, using keel bone fractures as an indicator.
Introduction
Several important issues must be taken into consideration when assessing layer-hen welfare. These include food, shelter, freedom from pain and disease, and the degree to which hens can express natural behaviours and cope with sometimes stressful environments (Layet al., 2011). Inlayer hens, skeletal health issues are of growing welfare concern due to their violation of two ofthese principles, causing severe debilitation and pain in those affected (Richardset al., 2011). The most common problems include osteoporosis and bone fractures, of which up to 90 per cent involve the keel bone (Layet al., 2011: Käppeliet al., 2011).
Discussion
Avian osteoporosis, a disease characterised byadecrease in mineralised structural bone, is associated mainly with conventionally caged layer hens (Layet al., 2011). However, Wilkins et al. (2011) showed that these layer hens have the lowest levels of bone fractures, despite having very fragile bones and a consequently increased susceptibility to bone fractures. Their research suggested that increasing levels of floor space and hen activity could significantly improve bone strength. On the other hand, inadequate housing, genetic factors or nutritional intake of calcium, phosphorus or vitamin D can predispose layer hens to osteoporosis (Layet al., 2011).
Arguably of more concern are layer hens housed in barn and free-range systems. Although these hens may perform more of their natural behaviours due to increased space and access to diverse resources, they are significantly more prone to keel bone fractures than conventionally caged hens, despite having increased bone strength as a result of increased levels of activity (Layet al., 2011: Wilkinset al., 2011). Those housed in systems with aerial perches are particularly susceptible (Wilkinset al., 2011). Perches can be advantageous in that they allow hens to exhibit their natural perching behaviours and thus are a great source of environmental enrichment and improved bone strength, but landing failures can result in bone fractures when hens jump off between perches (Wilkinset al., 2011). In a recent Swiss study by Kappelliet al. (2011), moderate or severe keel bone deformities could be found in more than 25 per cent of laying hens. This figure increased to 55 per cent when slight keel bone deformities were included. These fractures were detected by palpation along the edge of the keel bone to detect alterations, such as S-shaped deviations, bumps, depressions or proliferations. In a separate study by Wilkinset al. (2011), layer hens in furnished cages had the lowest mean level of keel bone deformities (36 per cent) while flocks housed in systems equipped with multilevel perches had the most severely deformed keel bones and the highest levels of keel bone damage (more than 80 per cent).Fracture calluses were evident upon histological examination of moderately and severely deformed keel bones, suggesting a traumatic etiology. Therefore, it is likely that collisions and landing accidents with perches are the cause of these bone fractures.
Furthermore, a layer hen will land with a force four times her bodyweight at a perch height of 30cm, but an increase in perch height to 60cm will result in a landing force seven times her bodyweight. A corresponding increase in poor landings from 2 per cent to 39 per cent can be measured at these heights (Sandilandset al., 2010). Wilkinset al. (2011) also made informal observations that descents to slats or litter from very high perches appeared to result in increased impact velocities and subsequently less controlled landings. This suggests that there is an increased opportunity for trauma, particularly ifobstacles are placed at or above ground level in flight paths between perches. As the impact of landing increases, the possibility of keel bone trauma increases; maximum perch heights above both litter and slats corresponded with the highest mean severity and prevalence of keel bone fractures (Wilkinset al., 2011). Thus we can deduce that an anticipated increase in flight velocity during perch descent may result in a higher risk of keel bone damage.
Gross skeletal damage has major welfare implications. Bone fractures are likely to result in extreme pain, especially given chickens are
known to possess sensitive pain perception mechanisms (Hockinget al., 2005). Moreover, most hens survive the immediate trauma of a keel bone fracture and undergo a six-week period of healing thereafter, when they are not only subject to the debilitating pain and discomfort caused by the keel bone fracture, but are also restricted in their access to food, water,nest boxes, range and perches (Richardset al., 2011). This is a serious violation of the five freedoms of animal welfare.
Fortunately, there are a number of methods that may improve the skeletal health of layer hens without compromising their welfare. Direct measures to improve bone strength and thus decrease the occurrence of osteoporosis include dietarysupplementation with Vitamin D and the selection of genetic lines with better mineralised bone (Kimet al., 2011). On the other hand, keel bone fractures could be minimised by lowering the heights of perches and strategically arranging them to reduce the overall number of obstacles between perches (Käppeliet al., 2011). Lowering stocking densities could also lower the risk of keel bone trauma by increasing floor space for landing, but may reduce the economic efficacy of extensive systems (Wilkins et al., 2011).
Conclusions
Skeletal health is a major animal welfare issue in extensive systems. Poultry farmers are faced with the ethical dilemma of having either conventionally caged layer hens with very weak bones due to osteoporosis, or non-caged hens with massive incidences of keel bone fractures. It must be noted that while provision of facilities, such as perches and floor space, in barn and free-range systems are hugely beneficial for bone strength and expression of normal behaviours (both of which are comprehensively reduced in battery cage systems), these benefits come at a trade-off for severely debilitating and painful keel bone fractures. More research must be conducted on the sustained improvement of skeletal health by looking at animal husbandry requirements and management of these different housing systems to uphold the five freedoms of animal welfare.
■ RICHARD NIALL
References
Hocking, P.M., Robertson, G.W., Gentle, M.J. (2005) Effects of nonsteroidal anti-inflammatory drugs on pain related behaviour in a model of articular pain in the domestic fowl. Research in Veterinary Science 78:1, 69-75. Käppeli, S., Gebhardt-Henrich, S.G., Fröhlich, E., Pfulg, A., Stoffel, M.H. (2011) Prevalence of keel bone deformities in Swiss laying hens. British Poultry Science 52:5, 531-536. Kim, W.K., Bloomfield, S.A., Ricke, S.C. (2011) Effects of age, vitamin D3, and fructooligosaccharides on bone growth and skeletal integrity of broiler chicks. Poultry Science 90:11, 2425-2432. Lay, D.C. Jr., Fulton, R.M., Hester, P.Y., Karcher, D.M., Kjaer, J.B., Mench, J.A., Mullens, B.A., Newberry, R.C., Nicol, C.J., O'Sullivan, N.P., Porter, R.E. (2011) Hen welfare in different housing systems. Poultry Science 90:1, 278-294. Richards, G.J., Nasr, M.A., Brown, S.N., Szamocki, E.M.G., Murrell, J., Barr, F., Wilkins, L.J. (2011) Use of radiography to identify keel bone fractures in laying hens and assess healing in live birds. The Veterinary Record 169:11, 279-283. Sandilands, V., Baker,L., Brocklehurst, S., Toma, L., Moinard, C. (2010) Proceedings of the 44th Congress of the International Society for Applied Ethology, “Coping in Large Groups”, Wageningen Academic Publishers, 249. Wilkins, L.J., McKinstry, J.L., Avery, N.C., Knowles, T.G., Brown, S.N., Tarlton, J., Nicol, C.J. (2011) Influence of housing system and design on bone strength and keel bone fractures in laying hens. The Veterinary Record 169:16, 414-420.
