2a: Why Dexters are Small

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The smallness of the Dexter can be due to either of two quite different factors, one genetic, the other a breeding strategy. The first factor is a gene that in its recessive form results in a "short-legged" animal. A short-legged Dexter has an obviously short length of the cannon bone on the front legs between the knee and the fetlock (ankle) joint. The first photo below shows two Dexter bull calves of the same age, one of which carries the short-leg gene. The second photo below contrasts two Dexter heifer calves of the same age, one also carrying the short-leg gene. NOTE: All four of these calves are registered Dexters and recognised as legitimate representatives of the breed, despite the noticeable differences in height between each member of the pair.
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Long-leg and short-leg Dexter bull calves due to genetic difference (Source: Debbie Davis, http://www.lazyj5dexters.com/).

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Dexter heifer calves of the same age, one carrying the short-leg gene (Source: Debbie Davis).

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The second source of smallness in a Dexter has been the selective breeding for size of those Dexters which do not carry the short-leg gene. This process seems capable of producing just as short an animal as the short-leg gene, and it often produces a Dexter which is more proportionate in character. Below is a Dexter bull that at first glance has the height and body of a short-leg Dexter but it has been verified through DNA testing as NOT carrying the short-leg gene.
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Shilton Pontius (M4241 DCS UK) at 4 years old, 41 inches high at the rump - non-short dun bull (Photo: D. MacIntyre).

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One of the reasons why Dexter breeders have pursued a selective breeding strategy is that the genetic source of short-legs has historically posed a problem for Dexters. The carrying of two short-leg genes by a Dexter foetus results in developmental abnormalities, early abortion and death - what has become known as the "bulldog calf". For more, see Post 2b: "Dexters and the genetics of leg-length". Experienced breeders easily avoid this by mating short-leg Dexters only with long-leg Dexters. With the identification of the short-leg gene and the development of a DNA test for it in 2002, Dexter breeders now have a certain method for avoiding the mating of two cattle with the short-leg gene. The days of the bulldog calf now belong to history.

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