Diagnosis and Surgical Treatment of a Chiari I-like Malformation in an African Lion (Panthera leo)
A 13-month-old intact male African lion (Panthera leo) presented with a 3-month history of lethargy, ventral flexion of the neck, abnormal vocalization, and ataxia. Hemogram and serum biochemistries were within normal limits except hypokalemia (2.7 mEq/L) and hypochloridemia (108 mEq/L).5 When no improvement was noted with oral potassium gluconate supplementation, a computed tomography scan was performed of the brain and skull and no abnormalities were noted. However, magnetic resonance imaging detected occipital bone thickening, crowding of the caudal cranial fossa with cerebellar compression and herniation, and cervical syringohydromyelia which was consistent with a Chiari I-like malformation. Foramen magnum decompression was performed to relieve the compression of the cerebellum. The animal recovered well, with subsequent resolution of clinical signs. Hypovitaminosis A has been proposed previously as the underlying etiology for this malformation in lions with similar clinical presentations.1-4,6,7 This lion’s serum and liver vitamin A concentrations were low (100 ng/ml and 25.31 μg/g, respectively) as compared to concentrations reported for domestic carnivores and suggest hypovitaminosis A as the underlying cause of this animal’s Chiari I-like malformation.
1. Baker JR, Lyon DG. Skull malformation and cerebellar herniation in captive African lions. Vet Rec. 1977;100:154–156.
2. Bartsch RC, Imes GD Jr., Smit JPJ. Vitamin A deficiency in the captive African lion cub Panthera leo (Linnaeus, 1758). Onderstepoort J Vet Res. 1975;42:43–54.
3. Chandra AMS, Papendick RD, Schumacher J, Homer BL, Wollenman P. Cerebellar herniation in captive lions (Panthera leo). J Vet Diagnostic Invest. 1999;11:465–458.
4. Hartley MP, Kirberger RM, Haagenson M, Sweers L. Diagnosis of suspected hypovitaminosis A using magnetic resonance imaging in African lions (Panthera leo). J South Afr Vet Assoc. 2005;76:132–137.
5. International Species Inventory System. Physiological data reference values. International Species Information System, Apple Valley, Minnesota. 2007.
6. O’Sullivan BM, Mayo FD, Hartley WJ. Neurologic lesions in young captive lions associated with vitamin A deficiency. Aust Vet J. 1977;53:187–189.
7. Tuch K, Pohlenz J. Partielle Cerebellarhernie beim Löwen (Panthera leo L.) Vet Pathol. 1973;10: 299–306.