Why Do Dalmatians Have Spots? The Genetics Behind Their Iconic Coat

The Dalmatian’s spotted coat is one of the most recognizable features in the dog world and is unique among AKC-recognized breeds. Although every Dalmatian puppy is born solid white, its distinctive spots begin to emerge within weeks and continue developing over time. Scientists have spent decades studying how these spots form, revealing a complex combination of genetic factors.

Spots and Patches: Understanding the Difference

The Dalmatian breed standard describes the spots, which may be black or liver but never both, as ranging in size from a dime to a half-dollar. Spots are generally smaller on the head, legs, and tail than on the body. Ideally, the they’re distinct rather than intermingled, and the ears are also spotted.

Spots are visibly, developmentally, and genetically different from patches, which aren’t allowed under the AKC standard. A patch is a solid mass of black or liver hair that is much larger than a normal spot and is present at birth. Large areas formed by overlapping or intermingled spots aren’t considered patches because they typically have uneven edges and may contain scattered white hairs.

This distinction often surprises new Dalmatian owners. Since Dalmatians are born completely white, any coloration visible at birth is a patch, not a spot. True spots usually begin appearing at about two weeks of age and may continue developing until a dog is more than a year old.

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A Long and Uncertain History

The Dalmatian’s history is, well, spotty. Ancient artwork, including some images dating to Ancient Egypt, depicted dotted dogs, although it’s difficult to know whether these representations accurately reflect real dogs or artistic interpretation.

The first known written description of the breed, referred to as Canis Dalmaticus, dates to 1375 and describes dogs with short white coats marked by round black spots. Later artistic works, including “Madonna with Jesus and Angels” from around 1600, portray Dalmatian-like dogs with spotting patterns that closely resemble those seen today.

The breed’s genetic origins are equally mysterious. Modern DNA studies suggest that Dalmatians are more closely related to sporting and pointing breeds, including the Weimaraner, than to any obvious family of spotted breeds. While some relatives, such as the Small Munsterlander or German Shorthaired Pointer, display ticking or flecking, none exhibit the Dalmatian’s uniquely bold spotting pattern.

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The Genetics Behind Dalmatian Spots

For decades, geneticists have tried to determine exactly how Dalmatian spots develop. Current research suggests that several genes work together to create the breed’s signature appearance.

The first requirement is a white coat background. This comes from genes at the white spotting locus, often referred to as the S gene. These genes produce varying degrees of white coloration. Dalmatians typically carry two copies of the extreme white variant, designated sw/sw, which creates the predominantly white coat necessary for spots to appear.

Researchers have also explored the role of ticking, a pattern that produces small flecks of color and doesn’t emerge until several weeks after birth. While ticking resembles spotting in some respects, ticked markings are typically much smaller than Dalmatian spots and often contain white hairs mixed with pigmented hairs. Dalmatian spots don’t contain white hairs within the spots themselves.

For many years, scientists theorized that a separate Flecking gene enlarged small ticked markings into the larger spots seen in Dalmatians. Under this model, the dominant Ticking gene worked together with two recessive copies of the Flecking gene to create larger markings.

In 2021, researchers uncovered another important clue. They found that all Dalmatians examined carried the genetic mutation associated with the roan coat pattern. Roan coats consist of dark hairs intermingled with white hairs and are seen in breeds such as the Australian Cattle Dog, German Wirehaired Pointer, Wirehaired Pointing Griffon, English Cocker Spaniel, Spinone Italiano, and, less commonly, the German Shorthaired Pointer.

Several of these breeds are also genetically related to the Dalmatian, providing another possible clue to the breed’s development.

Current evidence suggests that Dalmatian spots likely result from a combination of extreme white spotting, the roaning mutation, and flecking-related genetics. Researchers found little evidence linking Dalmatian spotting to the genomic regions thought to influence ticking, suggesting the breed’s spots may arise through a different mechanism altogether.

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How Coat Genetics May Affect Health

The genes involved in Dalmatian spotting may have implications beyond appearance.

Deafness occurs in Dalmatians at a higher rate than in most breeds. Researchers believe this may be partly related to the extreme white spotting responsible for the breed’s largely white coat. Interestingly, deafness also appears more frequently in some roan-coated dogs, even those without the same white spotting genes.

Scientists have noted that the gene associated with roaning, USH2A, affects hearing and vision in other species. Although additional research is needed, it’s possible that both white spotting and roaning-related genetics contribute to hearing loss in Dalmatians.

Another inherited health concern involves uric acid metabolism. Dalmatians excrete significantly higher levels of uric acid than most dogs, increasing their risk of developing bladder stones. This trait is caused by a recessive mutation in the SLC2A9 gene.

The mutation is genetically linked to the Flecking gene, leading researchers to suspect that selection for bold, attractive spotting may have unintentionally preserved the high-uric-acid mutation throughout the breed’s history. For many years, virtually every Dalmatian inherited the mutation from both parents, making it impossible to reduce the trait through traditional selective breeding.

As researchers continue studying the genetics of spotting, breeders hope to better understand how coat pattern, hearing health, and uric acid metabolism may be interconnected. Achieving the ideal combination of bold spotting, normal hearing, and lower uric acid levels remains a goal that depends on continued scientific discovery and breed-specific genetic research.

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