Diagnostic challenge in Veterinary Pathology : Progressive neurological disease in Aberdeen Angus calves in Argentina

Aberdeen Angus calves from a beef production farm located in Balcarce (37°43′56″S, 58°24′43″W), Buenos Aires province, Argentina, developed a chronic, progressive neurologic syndrome.The cases occurred in a cow-calf herd that was largely closed for more than 15 years, with replacement heifers sourced internally and only occasional introduction of outside breeding bulls.Over a period of approximately 3 years, six 4-to 6-monthold nursing calves in good body condition exhibited progressive neurologic signs.In 2016, one calf developed chronic neurologic signs and died after several weeks.In 2017, 4 additional nursing calves in good body condition died after developing similar clinical signs.In some animals, excessive salivation and limb rigidity were noted by farm personnel.The clinical course progressed over several weeks, culminating in recumbency and either spontaneous death or euthanasia.Empirical treatments, including antibiotics and anti-inflammatory drugs, were administered in some cases but failed to produce clinical improvement.In April 2018, another 6-month-old calf presented with progressive neurologic signs characterized by depression, reduced appetite, reluctance to move, progressive ataxia, postural instability, worsening incoordination when stimulated or forced to move, and generalized limb paresis.This prompted veterinary consultation, and upon clinical examination of the animal, a decision was made to euthanize the calf for diagnostic investigation.The subsequent gross examination revealed no significant lesions in the brain, spinal cord, or other major organs.