05/31/2026
I recently saw a post on a group where the OP shared a screen shot of a reputable breeder's puppy brag, condemning her for 'breeding for looks and not for health'. The pup was, if I recall m/n for CEA and m/m for MDR1.
Of course she had a few folks clammoring in and calling out this 'poor' breeder, but thankfully several group members stepped up and let her know that neither of these two genetic mutations is the end of the world for our dogs.
It's easy to panic when mutations are mentioned. I'm not saying not to be cautions and careful, but panic and banning breeding stock when you don't understand the disease or long term impact on the breed is irresponsible.
Within the rough collie world, approx 70% of collies are either m/n or m/m for MDR1. There is no difference between them, as we now know. If your dog carries one copy, it is affected. And if your dog carries zero copies, you treat it as affected because there have been (rare) cases of dogs who've tested clear who have had mild reactions.
To breed a healthier dog, you cannot simply breed only those who are clear because we've already got a ridiculous genetic bottleneck in the collie world. Healthy dogs have a COI of under 10%, and ideally less than 5%. Full siblings who mate, with zero ancestry overlap, are 25%.
Collies? 40%. So you can see how it would be an absolute DISASTER if we did not use 70% of our dogs as breeding stock. Especially since this is a drug reaction. Do not use those drugs that trigger the disease, and you do not have an issue with MDR1.
The other mutation the puppy in the shared post had was Collie Eye Anomoly, which at one time was a huge threat to the eyesight of our dogs. Dogs were tested and graded on severety (similar to hips now), and those with less of an issue were kept for breeding. This has helped over the years to reduce the severity of CEA in our dogs.
It's estimated that 70-90% of all rough and smooth collies carry at least one copy of CEA, so once again we do not simply not breed a dog who is a carrier or affected.
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Pictured below are Cirrus (our honorary 'smooth'...who's actually a lab but doesn't know it), Tiggy (two copies of CEA and MDR1, never an issue), Ted (one copy of MDR1), Ivy (CEA m/n, MDR1 m/n) and Thistle (CEA m/n). Also the tail end of Mustard the Cat who left the family photo early, lol!
We are fairly certain Tiggy may have limited vision in one eye, but at ten years of age it doesn't seem to bother her, and she's never had a reaction to drugs in her lifetime. She is the reason we can speak confidently. She came from a train wreck of a breeder, but she was our first collie and we love her!
