Recurrent Outbreaks of Myelodysplasia in Newborn Calves

Abstract

The present study records recurrent outbreaks of myelodysplasia of unknown origin occurring in a specific geographical location in the north of Spain, and involving up to 30% of the calves born in affected herds. The affected calves were of different breeds and displayed non-progressive signs of spinal cord dysfunction. The disease has occurred annually in February-March over a period of at least 15 years. Only calves born to cattle grazed on mountainside pastures and under high grazing pressure were affected. Seven calves were subjected to necropsy examination. Myelodysplasia was not associated with vertebral defects or arthrogryposis and involved the entire length of the spinal cord. Microscopically, there was abnormal distribution of the grey matter, aberrations of the central canal and failure of formation of the ventral median fissure. Infectious, nutritional and physical disorders were ruled out as possible aetiologies. A critical period of embryonic susceptibility to the causal agent was identified. This was during the time of secondary neurulation when cows in the early stages of gestation were grazed on mountainside pastures. Consequently, the presence of neuroteratogenic plants in these pastures is proposed as a likely cause. Two plants, Carex brevicollis and Erythronium dens-canis, which contain alkaloids, were identified on the mountainsides where affected cattle were grazed and not in other pastures, and are proposed as the possible aetiology of the disease.

Congenital diplomyelia and hydromyelia in two calves

“…Furthermore, antiepileptic medications during pregnancy increase the risk of NTDs in humans 14. In veterinary medicine, besides genetic factors, environmental factors such as a vitamin A deficiency, copper deficiency and the ingestion of neuroteratogenic plants during early pregnancy are described to be involved in the development of NTDs 3…”

“…For instance, degenerative conditions are common in later juvenile stages and throughout adulthood and usually have a slow, insidious onset and progressive course. Given that the neurological signs were present since birth with a static progression, congenital anomalies or malformations are considered to be the most likely causes 3–5. These include genetic mutations or intrauterine infections with BVDV, SBV, BTV, Neospora 6 7.…”

Clinical, MRI, and histopathological findings of congenital focal diplomyelia at the level of L4 in a female crossbred calf

“…Active inflammatory, infectious, degenerative and neoplastic diseases can cause a slow progressive course of the symptoms, but are less likely to cause symptoms from birth onwards. In this case, either congenital anomalies or malformations in the spinal cord between L4 and S1 are most likely to be the cause of the symptoms, although these typically cause a more static progression of the clinical symptoms [1,2,7,8].…”

“…Other cases of different types of myelodysplasia have also been diagnosed in calves. Calves with myelodysplasia have been described with varying symptoms like: sensory loss, non-progressive ataxia, 'bunny hopping', hypermetria, weakness in the hindlimbs and blindness [7]. Occurrence of myelodysplasia in the breeds Charolais and Hereford is thought to be higher compared to other breeds [7].…”

“…Calves with myelodysplasia have been described with varying symptoms like: sensory loss, non-progressive ataxia, 'bunny hopping', hypermetria, weakness in the hindlimbs and blindness [7]. Occurrence of myelodysplasia in the breeds Charolais and Hereford is thought to be higher compared to other breeds [7]. In Górriz-Martín et al [14], three cases were described of calves with nonambulatory paraparesis due to diplomyelia located in the lumbar vertebral column.…”