Congenital contractural arachnodactyly in cattle
Autosomal recessive disorder causing limb contracture in cattle.
Congenital contractural arachnodactyly (CA), or fawn calf syndrome, is an autosomal recessive genetic condition in cattle. It disrupts connective tissue in muscles, causing upper limb contracture—most noticeable in the hind legs—along with looseness in the lower limb joints. The disorder mainly appears in Angus cattle and related breeds like Murray Greys, resulting from a deletion on bovine chromosome 21.
Affected calves are typically born alive at normal weight, and most can walk and nurse, though about 20% cannot suckle and die shortly after birth. Signs include contracted upper limbs, overextended lower limbs at birth, and a curved spine. These symptoms often improve significantly as the calf grows. In mild cases, CA may be less obvious, showing up as tall stature, loose joints, and poor muscle development. Joint laxity makes affected cattle prone to early arthritis.
In Australia, all affected animals trace back to Freestate Barbara 871 of KAF, a cow born in Indiana, USA, in 1979. She is an ancestor of roughly half of all Australian Angus cattle, which limits the usefulness of pedigree checks for identifying carriers. If CA appears in a herd, bulls that have tested negative for the mutation should be used, since both parents must carry the defective gene for a calf to be affected. Known Angus sires carrying CA include Rambo 465T of JRS, Te Mania Kelp K207, Bon View Bando 598, SAF 598 Bando 5175, and Boyd On Target 1083.
The disorder was first identified in Victoria, Australia, in 1999 and has since been found in other countries. A genetic test became available in 2010.
- first_identified
- Victoria, Australia in 1999
Lore & Background
Congenital contractural arachnodactyly was first identified in Victoria, Australia in 1999, and has since been identified in other countries. Affected calves are usually born alive with normal body weight, and most can walk and suckle, although 20 percent cannot suckle and die soon after birth. Clinical signs include proximal limb contracture, congenital distal limb hyperextension, and congenital kyphosis. As the calf grows, signs significantly improve. In mildly affected calves, CA may be less obvious, presenting as tall stature, joint laxity, and poor muscling. Joint laxity predisposes affected cattle to the early onset of arthritis.
Reader's Guide
Congenital contractural arachnodactyly is significant in cattle breeding because it is an autosomal recessive disorder that can cause mortality in up to 20 percent of affected calves. The disorder is particularly notable in Angus cattle and associated breeds such as Murray Greys. In Australia, affected animals are descended from Freestate Barbara 871 of Kaf, a cow born in Indiana, US, in 1978, which is an ancestor of approximately half of all Angus cattle in Australia, limiting the usefulness of pedigree analysis in identifying potential carriers. Prevention involves purchasing bulls that have tested negative for CA, since both parents must be carriers for affected calves to be born. Known carrier sires include Rambo 465T of JRS, Te Mania Kelp K207, Bon View Bando 598, SAF 598 Bando 5175, and Boyd On Target 1083. A genetic test was developed in 2010, enabling more effective management of the disorder in herds.
Did You Know?
- CA is also known as fawn calf syndrome.
- The mutation causing CA is a deletion on bovine chromosome 21.
- Approximately 20 percent of affected calves cannot suckle and die soon after birth.
- A genetic test for CA was developed in 2010.
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