Fawn Calf Syndrome

Genetics Project



  • First discovered in Australia in 2001.
  • There it was recognized as a heritable disease affecting Angus cattle. In fact it was traced back to the four bull studs in the United States.
  • Since then it has been recognized worldwide in Angus cattle.

Description of the Disease

Contractual Arachnodactyly or Fawn Calf Syndrome (FCS) results from an abnormality of skeletal development. Calves generally have a normal birth weight but a variety of symptoms affect them.


  • Long and thin legs.
  • Contracture of the proximal limbs; specifically the hock and stifle.
  • Decreased range of motion in the hind end.
  • Most recognizable feature is the malalignment of the spine, resulting in an ached back. This is what gives the disease the name "Fawn Calf" due to them resembling baby deer.

These symptoms range in severity. 10% of cattle affected do not have the ability to stand or walk, which makes them unable to nurse. Without intensive nursing these calves usually die. There are also cases were the diagnosis can be difficult due to degree of symptoms. Often times by the four to six months of age they can appear normal.

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Why is this a problem?

Although calves may grow and develop normally, they will maintain a thin stature and decreased muscle formation. This makes it specifically difficult to have a cattle operation when calves do not have good muscle formation and growth.

What We Know

Genetic Transmission

  • Non-lethal autosomal-recessive genetic disease
  • Simply inherited
Phenotype: There is no visible change in phenotype between affected and non-affected cattle.


  • AA are homozygous dominant and non-carriers
  • Aa are heterozygous carrier
  • aa are homozygous recessive and affected

Example of Punnet Square and Genotypes

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Current Methods of Prevention

  • Laboratory DNA tests are available.
These were developed by the Angus Society of Australia, NSW Department of Primary Industries (Australia) and the Department of Animal Sciences University of Illinois. The tests have been utilized worldwide in order to identify the carrier(s) in populations, therefore reducing the number of calves affected.

  • The American Angus Association also has strict testing and registering rules in order to know carriers.
For example; all heifers must be tested and can registered regardless of outcomes. Bulls are required to be tested and can only be registered if they test negative.


With the information I have gathered I am concerned with the methods of prevention and eradication. In my opinion these animals do not live healthy or pain free lives and I wish there was something that could be done in order to completely remove it from the Angus cattle genes. The prevention does not seem enough because heterozygous carriers are still being bred together, thus, creating affected cattle. There are rules and regulations set in place for testing, however, I do not believe it is always done or logged correctly. If an Angus cattle has great genes for growth and meat quality I can almost guarantee the producer will not stop breeding that cow, especially with the somewhat low chance of creating an affected cow. Unfortunately for some producers it is about money and not the welfare of calves.


"American Angus Association Contractural Arachnodactyly (CA) Fact Sheet." American Angus Association. 10 Oct. 2013. Web. 29 Apr. 2015. <http://www.angus.org/pub/ca/CAFactSheet.pdf>.

Parish, Dr. Jane, and Dr. Trent Smith. "Managing Genetic Defects in Beef Cattle Herds." Mississippi State University Extension Service, 2010. Web. 29 Apr. 2015. <http://msucares.com/pubs/publications/p2622.pdf>.

"Contractural Arachnodactyly (CA)." Canadian Angus. 26 July 2010. Web. 29 Apr. 2015. <http://www.cdnangus.ca/breed/Contractural_Arachnodactyly.htm>.

Windsor, P., Kessell, A. and Finnie, J. (2011), "Neurological diseases of ruminant livestock in Australia. V: congenital neurogenetic disorders of cattle." Australian Veterinary Journal, 89: 394–401

Whitlock, B.K. ; Kaiser, L. ; Maxwell, H.S. “Heritable bovine fetal abnormalities.”

Theriogenology, 2008, Vol.70(3), pp.535-549

O'Neil, Dennis. "Probability of Inheritance." Basic Principles of Genetics. 1997. Web. 29 Apr. 2015. <http://anthro.palomar.edu/mendel/mendel_2.htm>.