Breed Improvement

Genetic Conditions


To maintain Angus breed integrity in Canada, and to assist our members with their mating decisions, the Canadian Angus Association identifies animals that have been tested for genetic conditions and reports the subsequent results of this testing.

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Genetic Basics

The Canadian Angus Association identifies animals that have been identified as carriers of, or have tested free of the causative genes for genetic conditions. Breeders have an ethical responsibility to disclose full pedigree information to potential buyers of an animal. Genetic condition test results are printed on registration certificates and published on our website. Breeders are encouraged to report all test results in sale catalogues.

Breeding a carrier animal to a non-carrier animal will result in half of the calves being both phenotypically and genotypically normal, while the other half of the calves, although phenotypically normal, will have inherited the defect causing allele or gene and be carriers.

A calf that has one carrier parent has a 50% chance of also being a carrier. DNA testing the calf will identify if it is a carrier or not. If a calf is born to parent animals that have not been tested for genetic conditions but has a known carrier animal in its grandparent generation, then it should also be tested because it has a 25% probability of having inherited the gene. However, it might be more economical to test the parent in this case. If the parent did not inherit the gene from the carrier grandparent then there is no way that the calf could have inherited the gene from the grandparent.

Breeding two carrier animals as shown in the following Punnett square will result in one-quarter of the calves being both phenotypically and genotypically normal, half of the calves looking normal but being carriers, and one-quarter of the calves inheriting both recessive alleles and being born affected.

The following Punnett square shows the results of a homozygous dominant (AA) animal being bred to a heterozygous or carrier (Aa) animal:

Canadian Angus Association Genetic Condition Policy*

*Approved September 22nd 2013, revised January 27th 2020.

To maintain Angus breed integrity in Canada, and to assist our members with their mating decisions, the Canadian Angus Association identifies animals that have been tested for genetic conditions and reports these test results. It is good ethical practice to disclose full pedigree information to potential buyers of an animal. Test results are printed on registration certificates and we encourage breeders to report all carriers in sale catalogues.

The following genetic conditions
are monitored by the Association:

This is not a lethal defect. Affected calves are born, after lengthened gestation periods, with high birth weights, and large prominent muscling. They have little fat and very fine bone structures.

There are several types of dwarfism in the Angus breed. Dwarf calves are typically born with very short legs and a stout fat body. A test is available for the D2 mutation of Dwarfism. Please contact the office for information and to arrange testing.

The Angus Society of Australia, with the assistance of Dr. Jonathan Beever (Professor, Department of Animal Sciences, College of Agricultural, Consumer and Environmental Sciences, University of Illinois), has been investigating the cause of calves born with extra limbs/heads (polymelia) since 2011. This research has led to a newly identified recessive genetic condition called Developmental Duplication or DD. Dr. Beever has identified the genetic mutation that causes this syndrome in beef cattle and developed a DNA test to help identify carrier animals and avoid affected calves. To date, only 20 affected calves have been reported. From low occurrence of affected calves and the higher probable frequency of the mutation in the Angus populations, Dr. Beever concludes that in most instances the cow suffers early abortion and the chance of seeing affected calves is low. The most common result is open cows because of embryonic loss with the less common result being calves born with more than four limbs and/or one head. As both of these results impact producer profitability, a DNA test is now available as a tool to identify carrier animals so that cattlemen might avoid breeding them. Please be aware that similar cases have been reported in other beef breeds, both Bos Taurus and Indicus; this is not an Angus-specific issue.

Although the impact of this mutation will be much lower in the Canadian Angus population than the American and Australian Angus populations, the Canadian Angus Association Board of Directors takes anything that can affect member profitability seriously. The Board of Directors will consider the implications of this genetic condition and the best interest of the breed and members and will advise our membership on the approach that will be taken. AI companies are already working with Dr. Beever to ensure that genetics currently being marketed are tested.

Scientific advances in the field of genetics, our membership’s ability to manage such conditions and the likelihood that the scientific community will continue to identify additional genetic conditions in all breeds in the future are some of the factors that the Board will consider. We will keep you advised on the Board's approach as it occurs.

Dr. Beever has tested 1,099 Angus bulls at the University of Illinois. The list of tested animals with a Canadian Herd Book impact is linked below. At this point, only Black Angus cattle have been tested.

Heterochromia Irides (HI) — White Eye
Rare ocular pigmentation abnormality, often called “white eye”. There is a grey-silver or white/blue ring observed around the iris of affected animals.

Oculocutaneous Hypopigmentation (OH)
Oculocutaneous Hypopigmentation (OH) presents very similarly to the already monitored genetic condition Heterochromia Irides (HI) or White Eye which was identified in beef cattle in the 1980s. Cattle affected by HI and OH have eyes with irises that are pale blue around the pupil with a tan periphery. In some beef breeds their hair coats have a slightly bleached color. While some affected calves have sensitivity to light, they are believed to be otherwise normal functionally and physiologically. Dr. Jon Beever from the University of Illinois, has screened numerous Angus bulls for the OH mutation. Of those, only one was identified as a carrier of the mutation, Sir Wms Warrant, (AAA 9196894) born in 1978. In 1982, Warrant was identified by the American Angus Association as a carrier of Heterochromia Irides (HI) based on abnormal calves sired by him. Although they are two separate genetic mutations, OH and HI exhibit many of the same characteristics.

This condition causes various degrees of hairlessness, affecting Angus; Ayrshire; Brangus; Holstein-Friesian; Hereford breeds. The condition is a simply inherited recessive trait.

Animals affected with Protoporphyria (PR) are sensitive to sunlight and develop scabs and open sores when exposed to sunlight. The liver is also affected and the animals may suffer from seizures. PR is inherited as a simple recessive trait.

Affected calves are born with a large quantity of fluid retained between the body and the skin. This results in larger bodies that usually require birthing assistance. Affected calves are stillborn. There are no suspected or confirmed cases in Canada.

Toes of the hoof are fused together in affected animals. This can range from one affected hoof to all four. This defect is not lethal.

Tibial Hemimelia (TH) causes large abdominal hernias. This recessively inherited condition is lethal.


The below genetic conditions are monitored and there is also a requirement to test for these conditions if there is a carrier in the first 2 generations of an animal’s pedigree.

The Canadian Angus Association acknowledges and seeks to identify carriers of the following genetic conditions:

This is a lethal defect caused by a recessive gene. Affected calves have a bent and twisted spine. The calves are small and very thin due to limited muscle development. Their legs are often rigid and may be hyper-extended. In some cases, this causes calving difficulties.

NH is a recessively inherited defect that causes excess fluid retention in the brain. The calves are born near term and have 25–35 pound birth weights. The cranium is markedly enlarged (volleyball to basketball sized). The bones of the skull are malformed. The cranial cavity is filled with fluid and no recognizable brain tissue is evident. The spinal canal is also dilated.

Affected calves of this lethal, recessively inherited defect are typically born premature and dead. The affected calves have a severely compacted jaw and brittle bones.

Contractural Arachnoloactyly(CA) is a non-lethal condition wherein calves are normally born alive and most can walk, suckle and survive. The birth weight of affected calves is normal. The phenotype is subtle and hence CA may not initially be recognized as an inherited defect. Affected calves at birth assume an abnormal crouched posture resembling an elk or deer fawn. In their first days of life, affected calves are also flat down on their pasterns. Although there is a reduced range of movement in the upper limb joints, particularly the hip, stifle and hock, there is an increased extensibility of the lower limb joints, particularly the pasterns. CA affected calves are reported as taller and more slender than their unaffected siblings.

Australian researchers assert that the inability to passively extend the hip, stifle and hock joints to the normal extent by pulling downwards on the foot of a newborn calf—while it is held on its side on the ground—is a valuable diagnostic sign in CA cases.

Affected calves can show significant recovery and usually appear relatively normal by 4 to 6 months of age. As weanlings and yearlings, CA affected calves appear lighter framed and lighter muscled, particularly in the hindquarters. Most perform poorly and remain tall, slender animals with poor foot conformation. The more normal appearance of CA cases as mature adults makes early evaluation of the phenotype essential. Australian researchers have also reported the early onset of degenerative arthritis in cows that were CA-affected as calves, particularly in the stifle joints.

The Condition
Alpha Mannosidosis (MA) is an inherited condition in beef cattle that affects the nervous system. In affected animals the Alpha Mannosidosis enzyme does not work optimally to break down sugars in lysosomes causing a buildup of sugars and deterioration of the central nervous system. Like AM, NH and OS this condition is fatal, however, symptoms do not normally develop until the animal reaches sexual maturity. At about yearling age affected animals develop head tremors, loss of muscle control and difficulty walking, aggression issues, failure to thrive, and ultimately die.


The History
MA is one of the oldest genetic defects known in beef cattle. The Australian Angus Association undertook an aggressive endeavor to eradicate the gene from their herdbook in the 1980s after several Australian calves were diagnosed with MA. Much of what we know about MA today is a result of their research and efforts. Calves affected by MA have been documented in several countries including Scotland and America, and in several different beef breeds including Aberdeen Angus, Galloway and Murray Grey.


The Genetics
Similar to AM, NH and OS, the gene that causes Alpha Mannosidosis (MA) is a recessive gene, requiring two carrier parents to be bred before an affected calf is ever seen. To date there have been no reports of an affected calf in Canada. The frequency of the recessive gene in the Canadian herdbook is minimal. However, carrier animals, which look normal, can still pass on the gene to future generations. A DNA test has been validated in North America so that these carrier animals can be identified.

DNA Testing

DNA testing is available for the following genetic conditions: AM, CA, DD, DM, MA, NH, OH and OS.

To request a DNA test please complete the DNA Test Request Form and return it to the office. The lab accepts hair, tissue, blood and semen. For more information on DNA sampling, please click HERE.

Tests cost $22 each.

Canadian Angus Association
Genetic Condition Process:

Once the Association has formally acknowledged and identified a genetic condition, the following actions are required:

  • Calves that have known carriers of a genetic condition in the first two generations (parental and grandparental) of their pedigree will need to be tested for the causative gene to be eligible for registration. If the animal is found to be a carrier of the causative gene it is eligible for registration and transfer. The subject animal’s genetic condition status will be noted on its registration certificate, including electronically.
  • The Association will send an email notification to all members with registered animals (purebred breeders) summarizing the information on any new developments on genetic conditions, both those that are Acknowledged and Identified as well as those being Monitored. The notification will refer members to the Association website.

The following procedures will be followed for potential and known carriers of a genetic condition:

  1. Status of Currently Registered Females and Bulls
    Notwithstanding any subsequent test results, all registered females and bulls with the impacted genetics in their pedigrees as of January 1st in the year following the Association’s identification and acknowledgement of a genetic condition shall remain registered.
  2. Testing of Animals
    Testing to determine whether an animal is a carrier, or free, of the causative gene of a genetic condition shall be conducted through the Canadian Angus Association.
  3. Publication of Test Results by the Association
    Results of the testing shall be noted on the Registration Certificate of subject animals, including electronically. The Association shall also maintain an updated list of each animal determined to be a carrier, as well as those who have tested free of such condition. Upon request, the Canadian Angus Association shall provide such a list at no cost to the requesting member.
  4. Right to Request a Second DNA Test
    In those instances in which an animal previously registered or seeking registration is tested and determined to be a carrier of the genetic condition (and is identified as such electronically on the Association’s website), the member owner of record may request that an approved laboratory conduct a second DNA test on a sample from subject animal. In order to process a request for a second test, the member owner of record must provide materials or samples sufficient to permit the laboratory to verify the parentage of the animal in question.
  5. Notations on Registration Certificates
    Upon testing of an animal for a genetic condition, the animal’s registration certificate shall be noted in one of the two following manners:
    1. the letter F designating “FREE” on the registration certificate of any animal that has been determined by such a test to be free of the genetic condition;
    2. the letter C designating “CARRIER” on the registration certificate of any animal that has been determined by such test to be a carrier of the genetic condition.

Reporting an Abnormal Calf

Members of the Canadian Angus Association are required to report abnormalities in their herds. If an abnormality is observed:

  1. Complete and submit a Calf Abnormality Report to the Canadian Angus Association office.
  2. Collect DNA samples (hair from calf, dam and sire) to keep on record for future reference.
  3. Verify parentage (DNA) of abnormal calf to both sire and dam.
  4. Collect photographs for future reference.
  5. Conduct a pedigree search for common ancestors.
  6. Complete a veterinary inspection, DNA analysis and/or pathology exam if required

AI bulls and Donor Dams

AI sires and Donor dams that have a known carrier of any genetic condition, for which there is a DNA test commercially available, within the first two (2) generations of their pedigree, are required to be tested prior to registration of calves.

Foreign Animals

Foreign animals with a known carrier of a genetic condition, for which a DNA test is commercially available, in the first two (2) generations of their pedigree must be tested for the causative genetic condition in order to be eligible for registration.

Abnormal Calves

Calves that are stillborn or born with abnormalities are most commonly affected by environmental factors such as lack of minerals, viral infection, or exposure to toxic materials. All abnormal calves should be reported to the Association using Calf Abnormality Report so that the Association can monitor the occurrence of abnormal calves.

The Canadian Angus Association’s genetic condition policy is designed to eliminate the probability of getting affected calves, the associated economic impacts and also to minimize the frequency of these genes within the Canadian Angus gene pool.

Genetic Conditions for which there is no DNA test

Animals that have known carriers of a genetic condition for which there is no DNA test commercially available in the first two (2) generations of their pedigree are eligible for registration.

*For animals born before September 22, 2013
Animals born before September 22, 2013 are subject to the Association Genetic Defect policy which required an animal to be tested free of any genetic condition for which there was a confirmed carrier in the first two generations of its pedigree.

Monitoring and Testing In Your Own Herd

To help members manage genetic conditions within their own herds, your Canadian Angus Association provides members with a Geneprob herd analysis report. These reports identify the probability of animals in your herd carrying the genes for several genetic conditions. The reports help members identify which, if any, animals should be tested. The herd analysis will provide a snapshot of your genetics and allow you to focus your testing economically. Contact the Association to request an analysis for your herd. Please see the current fee schedule for rates.

DNA Testing for Genetic Conditions

DNA testing is available as a tool to identify carrier animals so that breeders can avoid breeding carrier animals to prevent having affected calves and minimize the number of carriers in the Canadian Angus Herdbook.

DNA testing is available for the following genetic conditions: AM, CA, DD, DM, MA, NH, OH and OS. Tests cost $22 each.

To request a DNA test please complete the DNA Test Request Form and return it to the office. The lab accepts hair, tissue, blood and semen. For more information on DNA sampling, please click here.

If you have any questions about genetic conditions, please email or call the Canadian Angus Association office at 1-888-571-3580.