What is a “double merle” Aussie you ask? This term refers to a puppy bred by two merle colored Aussie parents. Many people are unaware, but when two merles (of any breed) are bred together, each puppy has a 25% chance of being born as a double merle. These puppies have excessive white coloration – lack of pigment – and this coloration causes loss of hearing, vision, or any combination of the two impairments. Most often, we find these puppies to be deaf, with vision impairments ranging from malformed pupils to a complete lack of eyeballs.
These Aussies are very different than “pattern white” Aussies – look here to see information on the difference in color genetics.
In the rescue world, we tend to refer to these Aussies as “Lethal Whites”. This is not because they have health issues that will cause their early deaths (as with Lethal White horses), but because being born as a double merle Aussie is nearly a death sentence for a puppy. If they are not culled at birth (typically done by those who purposefully breed two merle parents), they are dumped in shelters or on the sides of roads. While merle dogs are beautiful and often sought after, in the wrong hands these stunning and unique dogs can produce multiples of impaired puppies. “The Trouble With Merle”, written by C.A. Sharp, is an insightful look at this issue as it exists in accidental form, as well as intentional.
These Aussies can lead perfectly happy, healthy lives if loved and trained by owners willing to dedicate the time and patience to caring for them. It is very important to not view them as “handicapped” – while of course they have limitations, they do not know this. These Aussies are still playful, active, intelligent dogs.
Want help training a deaf and/or blind Aussie? Look here: Deaf and/or Blind Pup Education 101
Aussies aren’t the only herders who can be born deaf – any dog that comes in a merled variety can suffer from this handicap.
Also, Australian Cattle Dogs can be born completely deaf, but for different reasons than lack of pigment. These dogs can all live normal lives.