The Dalmatian coat color pattern is the most distinctive of all AKC breeds and is found in no other breed of dog. The Dalmatian standard describes the spots, which can be black or liver but never both, as varying in size from a dime to the size of a half-dollar and are usually smaller on the head, legs, and tail than on the body. Ideally, the spots will not intermingle and the ears are spotted.
Spots are visibly, developmentally, and genetically different from patches, which are not allowed per the AKC standard, and are described as a solid mass of black or liver hair that is muchly larger than a normal-sized spot. However, large masses formed by intermingled or overlapping spots are not patches and will have uneven edges and/or white hairs scattered throughout.
This distinction between spots and patches often comes as a surprise to new Dalmatian owners—as does the fact that Dalmatians are born solid white. Any coloration present at birth would be from a patch, not a spot. The colored spots don’t appear until roughly two weeks of age and may continue to develop until over a year old.
The History of Dalmatian Spots
The Dalmatian’s history is, well, spotty. Ancient pictures, some dating from Ancient Egypt, have depicted dotted dogs, but it’s hard to know how much was just artistic license. The first known written information about the Canis Dalmaticus (presumably the Dalmatian) appears in 1375, describing them as having short white hair with black round spots. Early paintings such “Madonna with Jesus and Angels“ (circa1600) show Dalmatian-like dogs with distinctive spotting that could pass for present-day Dals.
Even the Dalmatian’s genetic history is unclear. It fits in no obvious family, with its closest relationships seemingly with sporting dogs like the Weimaraner and other pointing breeds. While some of its relatives, such as the Small Munsterlander or German Shorthaired Pointer, also have flecked or ticked coloration, none has the distinctive spotting sported by the Dalmatian.
The Genetics of Dalmatian Spots
Those dashing dots have long fascinated not only dog lovers but also geneticists. For decades they have speculated about the speckled coats, with recent evidence pointing to a new model of Dalmatian spotting.
Dalmatian spots result from the interaction of genes at several different locations called the loci, which in genetics speak is a fixed spot on a chromosome where a genetic marker is located. First, the dog must have the genes for a white coat, known as the white spotting locus, or the S gene. These genes create a continuum of whiteness, with more white being recessive to less white. They are roughly categorized as S (for colored all over), si (for Irish-marked, or white trim and collar), sp (for patches of color on white), and sw (for extreme white coverage). To avoid patches, Dalmatians need to be sw/sw. Spots can’t be expressed on any other coat color, not even the palest of creams that might appear white.
Next, a Dalmatian has to have genes that can produce a different sort of spotting other than patches. One candidate is the T gene, the dominant form of which causes ticking. Ticking refers to small flecks of color on the body, and doesn’t appear until several weeks of age. But the spots from Ticking are much smaller than Dalmatian spots, more often a quarter of their size or less. Also, spots from Ticking commonly have white hairs interspersed among pigmented hairs. Dalmatian spots never have white hairs within them. The gene that causes ticking has not yet been molecularly identified, so no genetic test exists for it.
Geneticists theorized that Dalmatians might also carry a gene called Flecking, that might interact with Ticking to create larger spots. They hypothesized that the combination of the dominant Ticking gene (T) with two recessive forms (f/f) of the Flecking gene resulted in the normally small flecks of color to be larger spots.
However, in 2021 researchers discovered a new clue: All Dalmatians carry the genetic mutation associated with the roan coat pattern. Roan is a pattern of subtly spotted fur with dark hairs intermingled with white. It’s most notably seen in the Australian Cattle Dog, German Wirehaired Pointer, Wirehaired Pointing Griffon, English Cocker Spaniel, Spinone Italiano, and slightly less commonly, the German Shorthaired Pointer. Note that several of these breeds are in fact fairly closely related to the Dalmatian according to DNA research.
The current theory is that Dalmatian spots are the result of extreme white spotting (sw/sw), overlaid with spots created by the interaction of the dominant Roaning allele (R) with the recessive Flecking allele (f), with almost all correctly spotted Dalmatians being sw/sw R/R f/f. As for the Ticking gene, the researchers found no strong association with any genomic region with ticking, suggesting that Dalmatian spotting may not be related to a Ticking gene at all. The black spots are caused by the dominant B allele and the liver by the recessive b allele.
Dalmatians, Spots, and Health Issues
Unfortunately, deafness occurs in Dalmatians at a higher rate than most breeds, probably because deafness is more common in dogs with the gene for extreme white spotting. Interestingly, deafness is also more common in roan Australian Cattle Dogs as well as other roan dogs—even ones that don’t have the sw allele. It’s possible that the Roan mutation may also have an effect on hearing, especially as the gene (USH2A) is known to affect hearing and vision in other species. While more research needs to be done, it is possible that Dalmatian hearing is affected by both white spotting and Roaning genes.
Dalmatians produce much more uric acid in their urine compared to other dogs, and this places them at greater risk for bladder stones. The high uric acid output is caused by a recessive mutation in the SLC2A9 gene—a gene genetically linked to the Flecking gene. It is likely that in the development of the Dalmatian breed, selection for bold spotting due to the Flecking gene inadvertently selected for high uric acid output. As a result, until recently every Dalmatian inherited it from both of their parents. It was thus impossible to breed away from high uric acid production by selecting Dalmatians with low uric acid—because there weren’t any.
It may be that it’s not possible to produce Dalmatians with big bold spots, no patches, perfect hearing, and low uric acid production—but geneticists and breeders have not given up. To produce such dogs will require an additional understanding of just what makes the Dalmatian’s spots, as well as what causes so many to be deaf. Dalmatian owners can help by enrolling their dogs in a genetic research databank.