Genetics Australia

Contractural Arachnodactyly

Managing Fawn Calf in the Beef Industry

Contractural Arachnodactyly (CA) is a nonlethal genetic defect caused by a recessive mutation that affects Angus and Angus-influenced cattle. While CA-affected calves are born alive, and most can walk, suckle and survive, their upper limb joints (particularly hip, stifle and hock) have a reduced range of motion. Affected calves appear normal by four to six months of age, but most perform poorly and are relatively tall and slender, with compromised feet and leg conformation. Without DNA or progeny testing, carrier animals are indistinguishable from animals that are free of the condition.

A diagnostic test for CA developed by Dr. Jon Beever at the University of Illinois in collaboration with the American Angus Association is now available commercially through Zoetis Genetics.

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  • Testing of suspect animals is essential to manage propagation of the deleterious recessive gene, to meet association registry requirements, and to eliminate the negative impacts of CA.

    Samples for testing may be submitted in one of the following forms:

    • Hair follicles (Preferred Option). When sending hair samples, please make sure at least 25 follicles (bulb intact) are included to ensure an adequate volume of DNA to complete the test.
    • Blood FTA® cards
    • Semen sample
    • Whole blood samples in purple top tubes


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