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high-dose corticosteroids compared to placebo-treated patients (Steinsapir and Goldberg 2011). Recent animal studies also suggest that high-dose corticosteroids are toxic to the injured optic nerve (Steinsapir and Goldberg 2011). Given that the human and animal data suggesting that corticosteroid treatment is harmful and the lack of demonstrated clinical efficacy, corticosteroids are not used to treat TON in man (Steinsapir and Goldberg 2011). We are not aware of any horse with TON that has
recovered vision. Given that the likelihood that TON is more like TBI resembling ICH than an inflammatory insult to the optic nerve, we suggest that future therapy of horses with TON include systemically administered iron and calcium chelator therapy as early as possible in addition to high dose and sustained nonsteroidal inflammatory therapy. The iron chelator deferoxamine, at a dose of 20 mg/kg bwt subcutaneously twice daily, increases urinary iron elimination and decreases hepatic iron accumulation after administration of a blood transfusion to normal neonatal foals (Elfenbein et al. 2010). Deferoxamine is utilised in human patients for the treatment of acute iron intoxication and of chronic iron overload because of transfusion-dependent anaemias. Verapamil is a calcium channel blocker that may be used in TON cases at a dose of 2.2 mg/kg bwt subcutaneously 3 times/day.
Authors’ declaration of interests No conflicts of interest have been declared.
References
Blogg, J.R., Stanley, R.G. and Phillip, C.J. (1990) Skull and orbital blow-out fractures in the horse. Equine Vet. J. 22, Suppl. 10, 5-7.
Brooks, D.E., Komaromy, A.M. and Kallberg, M.E. (1999a) Comparative retinal ganglion cell and optic nerve morphology. Vet. Ophthalmol. 2, 3-12.
Brooks, D.E., Komaromy, A.M. and Kallberg, M.E. (1999b) Comparative optic nerve physiology: Implications for glaucoma, neuroprotection and neuroregeneration. Vet. Ophthalmol. 2, 13-26.
Elfenbein, J.R., Giguere, S., Meyer, S.K., Javsicas, L.H., Farina, L.L., Zimmel, D.N. and Sanchez, L.C. (2010) The effects of deferoxamine mesylate on iron elimination after blood transfusion in neonatal foals. J. Vet. Int. Med. 24, 1475-1482.
Feary, D.J., Magdesian, K.G., Aleman, M.A. and Rhodes, D.M. (2007) Traumatic brain injury in horses: 34 cases (1994-2004). J. Am. Vet. Med. Assoc. 231, 259-266.
Gleckman, A.M., Evans, R.J., Bell, M.D. and Smith, T.W. (2000) Optic nerve damage in shaken baby syndrome: detection by beta-amyloid precursor protein immunohistochemistry. Arch. Pathol. Lab. Med. 124, 251-256.
Hippocrates (1928) On Wounds in the Head, vol. III, translated by E.T. Withington, Loeb Classical Library, Harvard University Press, Cambridge, MA.
Hua, Y., Keep, R.F., Hoff, J.T. and Xi, G. (2007) Brain Injury after intracerebral hemorrhage. The role of thrombin and iron. Stroke 38, 759-762.
Hua, Y., Keep, R.F., Hoff, J.T. and Xi, G. (2008) Deferoxamine therapy for intracerebral hemorrhage. Acta Neurochir. Suppl. 105, 3-6.
Iwamoto, M.A. and Bstaendig, S. (1995) Recent advances in orbital and periorbital trauma. Ophthalmol. Clin. North Am. 8, 681-691.
Joseph, M.P. (1995) Traumatic optic neuropathy. Ophthalmol. Clin. North Am. 8, 693-708.
Kullmann, A., Marteniuk, J.V.,Williams, M.R., Holcombe, S.J., Mowat, F.M. and Mullaney, T.P. (2014) Bilateral traumatic optic nerve avulsion in a Thoroughbred gelding. Equine Vet. Educ. 26, 523-526.
Law, J. (1923) Diseases of the Eye. Special Report on Diseases of the Horse, US Dept of Agriculture, Washington DC. p 296.
Le Fanu, J. (2005) Wrongful diagnosis of child abuse – a master theory. J. R. Soc. Med. 98, 249-254.
Levin, L.A., Beck, R.W., Joseph, M.P., Seiff, S. and Kraker, R. (1999) The treatment of traumatic optic neuropathy: the International Optic Nerve Trauma Study. Ophthalmologe 106, 1268-1277.
Ma, M., Shofer, F.S. and Neumar, R.W. (2012) Calpastatin overexpression protects axonal transport in an in vivo model of traumatic axonal injury. J. Neurotrauma 29, 2555-2563.
Martin, L., Kaswan, R. and Chapman,W. (1986) Four cases of traumatic optic nerve blindness in the horse. Equine Vet. J. 18, 133-137.
Matsuzaki, H., Kunita, M. and Kawai, K. (1982) Optic nerve damage in head trauma: clinical and experimental studies. Jpn J. Ophthalmol. 26, 447-4461.
Maxwell, W.L., Povlishock, J.T. and Graham, D.L. (1997) A mechanistic analysis of nondisruptive axonal injury: a review. J. Neurotrauma 14, 419-440.
Nicolas, E. (1925) Veterinary and Comparative Ophthalmology, Translated by H. Gray. H and W Brown Pub, London. p 337.
Percival,W. (1876) Hippopathology Vol 3. The Disorders and Lamenesses of the Horse. Longmans, Green and Co., London, p 129.
Pieramici, D.J. and Parver, L.M. (1995) A mechanistic approach to ocular trauma. Ophthalmol. Clin. North Am. 8, 569-587.
Polyak, S. (1957) The Vertebrate Visual System. University of Chicago Press, Chicago. p 289.
Scrivani, P.V. (2013) Neuroimaging in horses with traumatic brain injury. Equine Vet. Educ. 25, 499-502.
Steinsapir, K.D. and Goldberg, R.A. (1994) Traumatic optic neuropathy. Surv. Ophthalmol. 38, 487-518.
Steinsapir, K.D. and Goldberg, R.A. (2011) Traumatic optic neuropathy: an evolving understanding. Am. J. Ophthalmol. 51, 928-933.
Wolf, J.A., Stys, P.K., Lusardi, T., Meaney, D. and Smith, D.H. (2001) Traumatic axonal injury induces calcium influx modulated by tetrodotoxin-sensitive sodium channels. J. Neurosci. 21, 1923-1930.
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