Inherited disorders of cattle: a selected review”

The strong inbreeding in the bovine population has increased the risk of occurrence of genetic diseases. In fact the wide use of few elite sires has enhanced the probability of the coupling of two mutated recessive genes in the genotype of an animal. Signs that might indicate that an abnormality is likely genetic in nature are: 1) the condition is more common in a group of related animals; 2) the condition is observed during all seasons of the year and in different geographic locations; 3) the condition appears more frequent as the level of inbreeding increases. In the recent past we had the opportunity of having a first hand experience of the following inherited diseases: Inherited central nervous system diseases Spinal Muscular Atrophy: the most worrisome inherited defect of Brown calves, characterized by severe muscular atrophy, progressive quadriparesis, and sternal recumbency beginning from an age of 3-4 weeks. Spinal Dysmielination: congenital neurological disorder mainly affecting Brown calves, characterized by congenital recumbency with typical extension of the hind limbs. The disease is due to a bilateral symmetrical dysmielination in the white matter of the spinal cord Bovine Progressive Degenerative Myeloencephalopathy (“Weaver” Syndrome): inherited disorder of purebred Brown cattle characterized by progressive bilateral hind legs weakness and ataxia, giving the gait a weaving aspect. Clinical findings become apparent from an age of 6-8 months. Spastic Paresis: the most worrisome inherited defect in the Romagnola breed, characterized by hyperextension of the hock and backwards moving of the hind legs. In the most severe cases the affected leg can be held permanently in extension and contractural fits cause a typical “pendulum” movement. Signs of Spastic Paresis appear usually at the age of 3 to 8 months and are due to a spastic contraction of the antigravitational, foot extensor muscle group. Spastic Syndrome: worrisome problem in mature bulls maintained in artificial insemination centres that can affect also cows in a recurrent or in a progressive form. It is characterized by intermittent bilateral spasm of skeletal muscles of the pelvic girdle and the rump, with consequent kyphosis and tremor of the hindquarters. The intensity and duration of the spasm progressively increase over time. Inherited congenital skeletal malformations Chondrodysplasia: also known as “Bulldog” calves and once common in the Romagnola breed. It is characterized by flat head with short nose and sloping forehead and by short and stumpy limbs. In the so called “Congenital Paunch Calf Syndrome” of the Romagnola calves besides a shortened and flattened face, and cleft palate, another main clinical feature is the abdominal distension due to considerable abdominal ascitic effusion. Complex Vertebral Malformation: the most worrisome inherited defect of Holstein calves, characterized by reduced body size, symmetrical arthrogryposis and malformations in the cervical and/or thoracic vertebral column (especially shortened neck and scoliosis). Multiple vertebral anomalies include hemivertebrae, fused and misshapen vertebrae and ribs, and scoliosis affecting mainly the caudal cervical and the thoracic regions. The homozygous condition is also responsible of a high embryonic or foetal mortality rate. Arachnomelia: congenital abnormality of the skeletal system giving the animal a spidery look and reported both in Simmenthal and Brown calves. The condition is mainly characterized by facial deformities, bone dolichostenomelia and angular deformities in the distal part of the hind legs. Bones of the legs appear to be more fragile than normal and spontaneous fracture during calving may injure the dam. Short Spine Lethal: rare skeletal defect characterized by strongly reduced dimension of the calf and marked and disproportionate shortening of the vertebral column due to spinal malformations, including fusion and/or variations in the...