Dwarf Cattle Breeds
Dwarfism is generally considered an undesirable trait in production cattle and now occurs quite rarely.
Dwarfs may be selectively bred as hobby, pet or "curiosity" animals.However in most cases preference should be given to "true" miniature breeds that do not carry dwarfism genes.
Dwarfism may be accidentally propagated during periods when it is fashionable for show cattle to have a stocky appearance.
Dwarfism in cattle can be caused by a number of different genetic conditions.
Achonroplastic dwarfism became common in Herefords during the 1950s due to large-bodied and short legged bulls being favored. It is named after the sound it made while breathing due to having short noses. This form of dwarfism was also reported, to a lesser extent, in the Angus and American shorthorn.
It took a determined effort to identify the genetic basis for this condition and largely weed it out of the gene pool for this breed. This task was made more difficult by the lack of an anatomical method for distinguishing non-carriers from heterozygous carriers--with only homozygous carriers being dwarfs.
Snorters are still sometimes produced in modern herds and an ongoing effort is needed to completely eliminate this condition from production herds.
Homozygous Lethal Chondrodysplasia is a version of dwarfism often found in Dexter cattle causes very short legs for offspring that carry one copy of the gene, and is lethal to those with two copies.
"Long Head" Dwarfism
Long Head dwarfism (dolichocephalic dwarfism) affects the legs but not the head and is a problem in Angus cattle.
There are a number of cattle breeds that are very small in stature. These are often traditional breeds, useful to small agrarian household because they require relatively little feed. The degree to which these breeds are dwarf versus miniature is not always clear.
Dwarfism may also be produced in genetical standard calves by a number of toxins.