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• ranges T3 (ng/dL) 31 67 50–160 T4 (µg/dL) 0.8 8 3–9 TSH (ng/mL) 0.34 0.13 fT4 (ng/dL) 0.45 3 0.7–1 As EMG findings, the occurrence of fibrillation potentials positive sharp waves and complex repetitive discharges has been described in dogs with hypothyroidism (13). Dysfunction of multiple cranial nerves (facial, trigeminal, and vestibulocochlear) with or without abnormal gait and postural reactions has been reported in dogs with hypothyroidism (10). Facial nerve damage and vestibular dysfunction were also seen in our patient. These findings were supported by the literature information. Cranial nerve deficits associated with hypothyroidism can involve single or multiple nerves, but those most commonly affected are the vestibular, trigeminal, and facial nerves. Clinical manifestations can be unilateral or bilateral; they include head tilt, nystagmus, strabismus, decreased facial sensation, and facial paralysis. (6). The clinical findings of the patient were similar to the symptoms in the literature. Peripheral neuropathy caused by hypothyroidism affects primarily middle aged and older individuals, especially of middle to large sized breeds (6,10,15). In our case, the patient was a middle sized breed (American Cocker) and 7 years old. There is no proven association that supports a connection between hypothyroidism and the occurrence of facial paralysis as a single sign in dogs. One source indicates that the facial dysfunction seldom improves on treatment using levothyroxine, which gives some reason to question if hypothyroidism causes facial paralysis alone (13). Treatment of dogs with hypothyroidism is easily achieved with oral levothyroxine supplementation (2,6). Dogs improve rapidly within a few days after the start of treatment (1). The majority of dogs with hypothyroidism with neurological deficits will show partial or complete resolution of their neurologic signs over 2–4 months, with improvement often noted within the first week of treatment (6). The patient had showed improvement in the 2 weeks after the use of oral levothyroxine. With appropriate treatment, hypothyroidism can be well managed and have an excellent prognosis (2). The dog’s facial paralysis was improved within 2 months of the administration of levothyroxine sodium. Treatment with thyroxine supplementation is successful in most cases of polyneuropathy and peripheral vestibular syndrome (13). Hypercholesterolemia, hypertriglyceridemia, and hyperlipidemia are commonly noted in serum biochemistry results in hypothyroidism (3,11). In our case, the dog had hypercholesterolemia, hypertriglyceridemia, and hyperlipidemia when the disease had been first recognized. Eventually, dogs with facial paralysis must be evaluated for thyroid functions to be certain of the cause and to help determine treatment duration. Further studies are necessary to determine the disturbances caused by hypothyroidism. 5 ms 50 µV Figure 6. After the treatment, normal facial view. Figure 7. Polyphasic motor unit potentials. References Suraniti, A.P., Gilardoni, L.R., Rama Llal, M.G., Echevarria, M., Marcondes, M.: Hypothyroid associated polyneuropathy in dogs: Report of six cases. Braz. J. Vet. Res. Anim. Sci., 2008; 45: 284–288.
• Scott-Moncrieff, J.C.: Clinical signs and concurrent diseases of hypothyroidism in dogs and cats. Vet. Clin. North. Am. Small Anim. Pract. 2007; 37: 709–722.
• Finora, K., Greco, D.: Hypothyroidism and myxedema coma. Compendium, 2007; 29: 19–32.
• Dixon, R.M., Reid, S.W.J., Mooney, C.T.: Treatment and therapeutic monitoring of canine hypothyroidism. J. Small Anim. Pract., 2002; 43: 334–340.
• McKenown, H.M.: Hypothyroisim in a boxer dog. Can. Vet. J., 2002; 43: 553–555.
• Blois, S.L., Poma, R., Stalker, M.J., Allen, D.G.: A case of primary hypothyroidism causing central nervous system atherosclerosis in a dog. Can. Vet. J., 2008; 49: 789–792.
• Dodds, W.J.: Thyroid disease and autoimmune thyroiditis. http://www.homevet.com/pet-care-library/item/336-thyroiddisease-and-autoimmune-thyroiditis-with-dr-dodds. Taeymans, O., Daminet, S., Duchateau, L., Saunders, J.H.: Preand post-treatment ultrasonography in hypothyroid dogs. Vet. Radiol. Ultrasound, 2007; 48: 262–269.
• Dixon, R.M.: Canine hypothyroidism. In: Mooney, C.T., Peterson, M.E., Eds. BSAVA Manual of Canine and Feline Endocrinology. 3rd ed., BSAVA, Gloucester. 2004; 76–94.
• Jaggy, A., Oliver, J.E., Ferguson, D.C., Mahaffey, E.A., Glaus Jun, T.: Neurological manifestations of hypothyroidism: a retrospective study of 29 dogs. J. Vet. Intern. Med., 1994; 8: 328–336.
• Panciera, D.L.: Is it possible to diagnose canine hypothyroidism? J. Small Anim. Pract., 1999; 40: 152–157.
• De Luca, C.J.: The use of surface electromyography in biomechanics. J. Appl. Biomech., 1997; 13: 135–163.
• Fors, S.: Neuromuscular manifestations of hypothyroidism in dogs. Svensk Veterinärtidning, 2006; 14: 11–17.
• Holiday, T.A.: Electrodiagnostic examination: somatosensory evoked potentials and electromyography. Vet. Clin. North. Am. Small Anim. Pract., 1992; 22: 833–857.
• Jaggy, A., Oliver, J.E.: Neurologic manifestations of thyroid disease. Vet. Clin. North. Am. Small Anim. Pract., 1994; 24: 487–494.