Genetic Abnormalities in a Calf with Congenital Increased Muscular Tonus.

Abstract

A 2-week-old female calf was referred to the Clinic for Ruminants at the Vetsuisse Faculty, University of Berne, Switzerland, with difficulty standing and muscle tremors since birth. Prior treatment by the private veterinarian with selenium, calcium, magnesium, and vitamins had not led to any improvement. The general status at arrival to the clinic was slightly reduced, though the calf was alert and attentive, and tachycardia (152/min) and tachypnea (80/min) were noticeable. Examination of the skin revealed an infected lesion on the fetlock of the left forelimb and several superficial lesions. Gastrointestinal, respiratory, and urinary tracts were without important abnormalities. The musculoskeletal system was normally developed, no atrophy was noticed, but the calf remained in a recumbent position unless lifted up and helped to stand. When standing, it showed tremor, ataxia, and could only move backward with hypermetria in the hind limbs and tip-toe-standing of the front limbs (Fig 1). Consciousness was normal but the calf was unable to orientate itself in its surroundings. Cranial nerve examination showed no deficits. Muscle tone was generally increased in the limbs. No painful reaction was noticed upon palpation of the limbs. The spinal reflexes were generally reduced. Sensibility was normal in the neck and shoulder area, but reduced in the limbs. The head and neck could be moved in all directions and the ears were symmetrical and loose. The clinical signs were localized in the peripheral nervous or musculoskeletal system. Based on the clinical signs of weakness, stiffness, trembling, and inability to stand up on physical examination, white muscle disease was considered a possible differential diagnosis, as Switzerland is known for its selenium-poor soils and high prevalence of selenium deficiency in calves. A blood chemistry profile revealed no relevant abnormalities, muscle enzyme activities were within normal limits. Further differential diagnoses associated with increased muscle tone, such as spastic paresis and tetanus, or with abnormal footing, as deforming ankylosis of the coffin joint, were considered unlikely based on the clinical findings, and no further diagnostic steps were undertaken. To exclude a bone lesion in the left fetlock, a radiographic examination of the joint was conducted which revealed no abnormality. A complete blood count was within normal limits. A lumbar puncture was not conducted as the problem of the calf had been localized in the peripheral nervous or musculoskeletal system. The calf was treated with antibiotics (procaine-penicillin 30,000 IU/kg SID s.c.) because of the deep lesion on the left fetlock. In addition, the calf was treated with vitamins of the B-complex (5 mg/kg thiamine, 2.5 mg/ kg pyridoxinhydrochloride SID i.m.) and selenium (sodium selenite 0.25 mg/kg, alpha-tocopherol 5 mg/kg s.c. once). The calf was assisted to stand several times a day, and feed and water was always provided for the calf to consume in recumbent position. The movements of the calf did not improve with treatment, however, it always had a good appetite, and was bright and alert. The owner did not wish any further examinations such as electromyography, or nerve or muscle biopsies. Based on the calf’s history of clinical signs since birth and lack of improvement despite treatment, on the clinical presentation and lack of specific findings matching the most common musculoskeletal diseases, congenital disease was suspected and veterinary geneticists were contacted during the calf’s stay at the clinic in order to investigate possible genetic causes for the disorder observed in this calf. The calf was of especially high breeding value for the owner, who insisted to take the calf home for further care. The calf was released from the clinic under the agreement that it would be brought back for further examinations or necropsy if it did not improve. Information was gathered approximately weekly by telephone conversation. A month after returning home, the From the Institute of Genetics, Vetsuisse Faculty, University of Berne, Berne, Switzerland (Wiedemar, Jagannathan, Drogem€ uller); Clinic for Ruminants, Vetsuisse Faculty, University of Berne, Berne, Switzerland (Riedi, Meylan). This work was performed at the Vetsuisse Faculty of the University of Berne at the Clinic for Ruminants and the Institute of Genetics. Corresponding author: M. Meylan, Clinic for Ruminants, Vetsuisse Faculty of the University of Berne, Bremgartenstrasse 109a, 3012 Berne, Switzerland; e-mail: mireille.meylan@vetsuisse.unibe.ch. Submitted February 15, 2015; Revised May 6, 2015; Accepted July 21, 2015. Copyright © 2015 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals, Inc. on behalf of American College of Veterinary Internal Medicine. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes. DOI: 10.1111/jvim.13599 Abbreviations: