Merle or Dapple as some call it is a currently up and coming coat color for labradoodles that is incredibly striking. It is similar to the stereotypical Australian Shepherd or Shetland Sheepdog and is shown as irregular blotches of fur within black/grays or tans on a lighter backing. Blue and partially blue eyes are often seen with the merle pattern, as well.

What most people don't know is that labradoodles with a Double Merle gene have an very increased risk in the health department. This comes about when one dog with the merle gene (carriers of the Mm genotype - which is a dominant gene) are bred with another carrier. This produces puppies with a double merle gene (MM genotype) that often have permeant health problems or disabilities. Merle carriers can also not show to be merle in their coat appearance but still carry the gene. 

Some of the health issue of a double merle (MM genotype) are:-
- Deafness in one or both ears
- Microphthalmia, leading to small, deformed, and often non-functional eyes
- Night blindness
- Microcoria, meaning the eyes are missing the muscles that cause them to dilate
- Eye deformations, like missing the third eyelid or iris clefts
- Sensitivity to direct sunlight and sunburn

With mandatory health testing, ethical breeding practices & standards, breeders can reliably breed merle puppies that are healthy and risk free. However, this is a clear show of how important it is to know that the breeders you are considering purchasing a puppy from are doing their due-diligence by understanding the importance of genetic testing. A simple oversight on a single gene in the breeding stages can set a whole litter up for failure.