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| + | [[Image:Working donkeys.jpg|right|thumb|150px|<small><center>Working donkeys (Image courtesy of [http://drupal.thedonkeysanctuary.org.uk The Donkey Sanctuary])</center></small>]] |
| + | =Distal interphalangeal joint flexural deformity= |
| + | [[Image:Flexural deformity donkey.jpg|right|thumb|250px|<small><center>Flexural deformity (Image courtesy of [http://drupal.thedonkeysanctuary.org.uk The Donkey Sanctuary])</center></small>]] |
| + | [[Image:Stage 2 flexural deformity donkey.jpg|right|thumb|250px|<small><center>Lateral radiograph of stage 2 contracture showing hoof wall past vertical and demineralisation of tip of pedal bone. (Image courtesy of [http://drupal.thedonkeysanctuary.org.uk The Donkey Sanctuary])</center></small>]] |
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| + | Flexural deformity of the distal interphalangeal joint is seen in donkeys. In the UK it is usually recognised in young rapidly growing animals on a relatively high plane of nutrition and may have the same multifactorial aetiologies as in the horse. Working donkeys overseas also suffer the condition – often in such a severe form that the dorsal hoof wall becomes parallel to the ground surface. In these cases, overwork, concurrent distal limb pain and nutritional deprivation may play a role. |
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| + | ==Clinical signs== |
| + | |
| + | As in the horse, the deformity may be referred to as: |
| + | *'''Stage 1''', where the dorsal hoof wall has not passed the vertical |
| + | *'''Stage 2''', where the dorsal hoof wall has passed the vertical |
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| + | ==Diagnosis== |
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| + | Donkey foals and young stock should have their hoof-pastern-axis (HPA) regularly assessed on a firm surface. |
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| + | ==Treatment== |
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| + | Those that are starting to show flexural deformity should have the '''plane of nutrition reduced''' and conservative treatment measures instituted. These measures include '''rasping the heels''' to restore a normal HPA and possible application of '''corrective glue shoes''' to protect the toes from excessive wear. |
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| + | In cases where a '''Stage 2 deformity''' is present, '''surgery is required''' to correct the defect. |
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| + | ==Surgery== |
| + | [[Image:Lateral view pre-tenotomy donkey.jpg|left|thumb|200px|<small><center>Lateral view pre-tenotomy (Image courtesy of [http://drupal.thedonkeysanctuary.org.uk The Donkey Sanctuary])</center></small>]] |
| + | [[Image:Lateral view post-tenotomy donkey.jpg|right|thumb|200px|<small><center>Lateral view post DDF tenotomy mid-cannon, also using ‘glue-on’ therapeutic shoe. (Image courtesy of [http://drupal.thedonkeysanctuary.org.uk The Donkey Sanctuary])</center></small>]] |
| + | [[Image:Shoe with toe extension.jpg|right|thumb|200px|<small><center>Shoe with toe extension (Image courtesy of [http://drupal.thedonkeysanctuary.org.uk The Donkey Sanctuary])</center></small>]] |
| + | [[Image:Post-tenotomy radiograph donkey.jpg|right|thumb|200px|<small><center>Post-surgery radiograph showing shoe (Image courtesy of [http://drupal.thedonkeysanctuary.org.uk The Donkey Sanctuary])</center></small>]] |
| + | Pre-operatively, '''radiographs''' should be taken to assess the distal phalanx; degenerative changes reduce the likelihood of a good outcome. The degree of tension and any abnormal thickening or pain in the flexor tendons should be assessed. At [http://drupal.thedonkeysanctuary.org.uk The Donkey Sanctuary] we like to arrange for a skilled farrier to be present during the assessment and subsequent surgery. This enables the farrier to be able to apply glue-on shoes while the donkey is still slightly sedated. If more than one limb is to be operated on, front limbs can be operated on with a two-week delay between surgeries, or a fore limb and contra-lateral hind limb may be |
| + | operated on simultaneously, with a two-week gap for the opposing limbs. |
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| + | There are three sites for performing the surgery, the simplest being '''tenotomy of the deep digital flexor tendon (DDFT) in the mid-cannon'''. This can be performed in the standing animal under [[Sedatives and Tranquilisers|sedation]] and [[Local Anaesthetics|local anaesthetic]]. This operation results in a pasture-sound animal, and even working donkeys have performed acceptably after the surgery. There is, however, thickening and scarring in the mid-cannon area. |
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| + | DDFT tenotomy can also be performed in the '''mid–pastern'''. In this site the tendon sheath is penetrated and the operation must be carried out under '''general anaesthetic'''. |
| + | A better cosmetic result is obtained, but problems can occur if the cut tendon recoils within the sheath. |
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| + | '''Desmotomy of the accessory ligament of the DDFT''' is the third method of surgical treatment. again this requires '''general anaesthesia'''. This technique is only really suitable for Stage 1 deformities. In the donkey an extra head on the accessory ligament may reduce the effectiveness of this surgery (N. Matthews, personal communication). |
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| + | ===Tenotomy of the DDFT in the mid-cannon site=== |
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| + | This can be performed in the '''standing, sedated donkey'''. For analgesia a '''subcarpal nerve block''' is used and/or '''local skin infiltration'''. The leg is clipped and prepared aseptically. A small '''skin incision''' is made on the '''lateral''' aspect |
| + | of the limb at the '''mid-metacarpal level'''. The tendons are identified manually and curved artery forceps used to '''separate the DDFT''' from the superficial digital flexor tendon (SDFT). Care must be taken to <u>avoid the blood vessels and nerves coursing laterally</u>. A tenotome is inserted into the DDFT and turned through 90º so that the '''DDFT is divided'''. At this |
| + | point a significant gap should appear and the tendon can be checked for complete severance. The '''subcutis and skin is sutured routinely''' and the '''leg bandaged'''. [[NSAIDs#Phenylbutazone|Phenylbutazone]] is administered post-op for five to seven days. |
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| + | After this procedure, the farrier can apply a shoe with a toe extension to help in realigning the HPA. Although theoretically over-extension of the hoof could occur, in practice we have not experienced this. |
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| + | The donkey should have '''box rest for 10 to 14 days''', then '''restricted exercise''', depending on its temperament. If they are not restricted, young boisterous animals can over-exercise and delay healing of the tendon, while sensible animals may heal adequately on paddock rest. |
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| + | ==References== |
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| + | * Thiemann, A. (2008) Surgery In Svendsen, E.D., Duncan, J. and Hadrill, D. (2008) ''The Professional Handbook of the Donkey'', 4th edition, Whittet Books, Chapter 16 |
| + | |
| + | For more details on this condition in the donkey, the following references are suggested: |
| + | * Carmona, A.G., Sevilla, M.A.T., Sevilla, H.C., and Cabanas, A.L. (1997). ‘Correccion de la contraccion del tendon flexor profundo por medio de un herraje ortopedico en equidos’. ''Vet.Mex.'' 28 (2). pp175-177. |
| + | * Daniels, L.E., Conine, T.A., and Jackson, D.A. (1990). ‘A rehabilitation team approach to correct flexural deformities in a donkey foal’. ''Canadian Veterinary Journal 31''. pp 297-299. |
| + | * Walmsley, J.P. (1995). ‘Flexural deformities of distal interphalangeal joints in a group of young donkeys’. ''Equine Veterinary Education 7''(1). pp 4-6. |
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