Genetic Conditions

Confirmed Genetic Condition Carriers

Click on the condition names below to access a list of known genetic carriers of that condition.

You can also use the Online Animal Inquiry to access a list of known genetic carriers. Use the “Select if” drop down menus and select the “Animal is a Carrier” of whichever condition you are searching for. Click Search. This will populate all the animals that have been confirmed carriers for the condition you selected.
You can also search animals that have tested free of the MD or DB conditions. For example, “Animal is Tested Free for MD”.

Please note that if an animal was tested through the American Hereford Association, the testing result will likely not be reflected in the Canadian Hereford Association Animal Inquiry. Please visit the American Hereford Association Animal Inquiry to check the testing status in the USA. You can search for animals either by inputting the animal’s name or AHA registration number or by scrolling down in the sidebar, expanding the DNA menu and selecting the condition(s) you would like to search for and then clicking search at the top.


Partial to almost complete lack of hair. Affected calves are often born with very short, fine, kinky hair that may fall out leaving bare spots or areas particularly susceptible to rubbing. The condition may vary in expression as the animal matures and is usually less noticeable in older animals. The haircoat color will sometimes appear “frosted” or “silverish.” Tail switch may be underdeveloped.


Carrier Hereford bulls or females when mated to black cattle can produce offspring with a haircoat that is gray, smokey or chocolate color.

Idiopathic Epilepsy

Age of onset or first seizure can be vary, ranging from birth to several months of age. Occurrence and persistence of seizures may be influenced by environmental stressors such as temperature extremes or increased physical activity. Upon initial onset of seizure episodes individuals will typically lie on their side with all limbs extended in a rigid state. Manual flexing of the limbs is possible, but return to the extended position occurs after release. Seizure episodes may last from several minutes to more than an hour.

Maple Syrup Urine Disease (Neuraxial Edema)

Calves are typically born without symptoms but by 2-4 days of age become slow, dull and eventually recumbent. The calves will often throw their heads back, lying on their side unable to rise. These calves may have some swelling of the brain at autopsy, but diagnosis requires laboratory investigation. The calves have a defect in an enzyme that breaks down complex amino acids in the diet and the buildup of these in the body creates the urine odor and brain damage. The disease name comes from the smell of urine observed in human babies (not always noted in calves).

Mandibulofacial Dysostosis

The anatomic features overlap with a variety of other facial defects and can include cleft palate, brachygnathia (short jaw) and camplygnathia (crooked jaw or face). The unique and consistent hallmarks of the condition include unusual bilateral skin tags just behind the corner of the mouth. These tags are attached to an unusual bone formation. There may be additional skin tags near and/or below the ears. A ridge of Meckel’s cartilage, a structure usually present only during embryonic development, is retained in these calves and attaches to the skin tag. This cartilage is encased in bone as it is followed from the skin tag toward the base of the ear. This bone attaches specifically to the zygomatic process of the temporal bone (just above the articulation of the jaw). The calves’ ears are sometimes slightly small and floppy. Muscles of the jaw are underdeveloped, and calves may have an elongated oral opening appearing as an exaggerated smile. The nursing reflex is present, but nursing is not vigorous. Calves with the additional cleft palate, severely shortened or crooked jaws are debilitated in ability to nurse. Calves with the defect are live born but are not able to thrive.

Delayed Blindness

Delayed Blindness (DB) is caused by retinal degeneration within the eye. Cattle affected by DB are not born blind, but vision loss is noticeable near or just after one year of age. Initial clinical signs may include the animal having difficulty navigating their surroundings, bumping into stationary objects, and slowly navigating unfamiliar terrain. These cattle will also lack a menace responsive (reaction to something being moved toward the eye). Cattle are remarkable at adapting; if in a stable environment vision loss may be severe when first noticed. Unless secondarily injured, the eye appears normal to the casual observer. A detailed ophthalmologic evaluation of the retina in the back of the eye can confirm retinal degeneration. Diagnosis can also be established by genetic testing.

When conducting online searches, you may see animals which have codes listed in curly brackets {} between the animal and registration number. These codes represent either awards the animal has received or genetic abnormalities the animal is known to be tested free of or a carrier of. Currently used codes for genetic conditions are listed below.

HYF=Hypotrichosis Free (tested and results indicate animal is not a carrier)
HYC=Hypotrichosis Carrier
HYP=Hypotrichosis Potential Carrier
DLF=Dilutor Free (tested and results indicate animal is not a carrier)
DLC=Dilutor Carrier
DLP=Dilutor Potential Carrier
IEF=Idiopathic Epilepsy Free (tested and results indicate animal is not a carrier)
IEC=Idiopathic Epilepsy Carrier
IEP=Idiopathic Epilepsy Potential Carrier
MSUDF=Maple Syrup Urine Disease Free (tested and results indicate animal is not a carrier)
MSUDC=Maple Syrup Urine Disease Carrier
MSUDP=Maple Syrup Urine Disease Potential Carrier
MDF=Mandibulofacial Dysostosis Free (tested and results indicate animal is not a carrier)
MDC=Mandibulofacial Dysostosis Carrier
MDP=Mandibulofacial Dysostosis Potential Carrier
DBF=Delayed Blindness Free (tested and results indicate animal is not a carrier)
DBC=Delayed Blindness Carrier
DBP=Delayed Blindness Potential Carrier

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