Congenital and Inherited Anomalies of the Musculoskeletal System in Cattle

Bulldog-type bovine chondrodysplasia, also known as bulldog calf syndrome, is a lethal congenital syndrome in cattle. It is inherited as an incompletely dominant trait of Dexter cattle. Several mutations are associated with the phenotype. In addition to Dexter cattle and crosses, it has been reported in Holstein, Nellore, and Zebu cattle.

Calves with bulldog-type bovine chondrodysplasia can be carried to term; however, they are usually aborted by the seventh month and missed by the owner.

If they are born, they are identified by their much smaller than usual size; extremely short limbs, which are usually rotated; domed head with protruding mandible; and large abdominal hernia (see image of calf with bulldog-type chondrodysplasia). Their tongue is normal size and therefore protrudes from the mouth; the hard palate is absent. These calves lack ossified bones due to failure of endochondral ossification.

Bulldog-type chondrodysplasia, calf

Image

Courtesy of Dr. Shari Kennedy.

Telemark lethal bovine chondrodysplasia is an inherited autosomal recessive trait; thus, the parents are normal.

Affected calves have head deformities similar to bulldog-type bovine chondrodysplasia calves (domed head, protruding mandible, protruding tongue) and small, rotated limbs. They are usually born alive but cannot stand, and they suffocate shortly after birth.

A mild form exists in Jersey cattle and can result in viable calves.

Reported in Hereford and Angus breeds, brachycephalic (snorter) dwarfism is now a relatively rare form of dysplasia.

Calves are born with short, broad heads; bulging foreheads; and protruding mandibles (though less severe than in bulldog and Telemark calves). The eyes bulge, and the vertebral column is short due to the presence of short, flat vertebrae. The short vertebral column results in a short abdomen; thus, eructation is limited, and calves become gas-distended and prone to recurrent ruminal tympany.

Dolichocephalic (long-headed) dwarfism is similar to snorter dwarfism. The main difference is that the head is proportionally larger and tapers to a pointed muzzle. Calves have crooked limbs and a slow growth rate and are unthrifty. 

Limber leg is a hereditary condition of Jersey cattle, apparently controlled by a simple lethal autosomal recessive gene.

Some affected calves are born dead. Living calves appear normal at birth but are unable to stand because of incompletely formed muscles, ligaments, tendons, and joints. The shoulder and hip joints can be rotated in any direction without apparent discomfort.

Diagnosis is based on clinical signs, necropsy findings, and identification of carrier animals.

Double muscling is an overdevelopment of the musculature of the shoulder, back, rump, and hindquarters, separated by deep creases, particularly between the semitendinosus and biceps femoris, and between the longissimus dorsi muscles on each side. Necks of double-muscled cattle are shorter and thicker, and their heads appear smaller.

Associated disorders of double muscling include hypoplastic reproductive tracts, delayed reproductive age of maturity, lengthened gestation, and increased birth weights combined with dystocia.

The condition occurs in various beef breeds, including Charolais, Santa Gertrudis, South Devon, Angus, Belgian Blue, Belgian White, and Piedmontese.

Double muscling is caused by a pair of incompletely recessive genes that result in the inhibition of myostatin activity in various degrees of the condition. Succinic dehydrogenase activity is substantially decreased in affected calves.

Myopathy of the diaphragmatic muscle is an inherited disorder of Meuse-Rhine-Yssel and Holstein-Friesian cattle. The diaphragmatic and intercostal muscle fibers undergo atrophy and develop distinctive corelike lesions.

Clinical signs manifest at 2–10 years old and include loss of condition and appetite and recurrent bloat due to decreased rumen contractility. 

Complex vertebral malformation is a lethal congenital defect of Holstein calves characterized by shortening of the cervical and thoracic vertebral column due to multiple hemivertebrae, fused and misshapen vertebrae, and scoliosis. Affected calves are small, with persistent arthrogryposis of the forelimbs and possibly the hindlimbs. Approximately 50% of cases will have concurrent cardiac defects.

Spastic paresis is a progressive neuromuscular disease affecting one or both hindlimbs due to spastic contractions of the gastrocnemius muscle. The disease first manifests as exaggerated straightness of the hock, which progresses to hock and stifle hyperextension. The calf extends the limb caudally and swings out the leg to walk. Abnormal loading of the contralateral limb often results in tarsal varus.

Disease usually manifests at 3–7 months but occasionally occurs in adults. An important differential diagnosis is upward fixation of the patella.

Treatment is surgical: either partial tibial neurectomy (associated with recurrence) or tenotomy of the gastrocnemius. The disease is inherited, so removing the bloodline from the herd is advisable.

In dairy cattle with brown atrophy, the skeletal muscles and myocardium are yellow-brown to bronze. The masseter muscles and diaphragm are affected most frequently. No clinical disease results.

Certain breeds (eg, Ayrshire) are more predisposed than others. Microscopically, brown lipofuscin pigment granules accumulate under the sarcolemma or centrally in muscle fibers. The inheritance pattern of 1 affected and 3 normal offspring suggests that this condition may result from inheritance of a simple recessive gene.