Lethal Whites UK

Disability is just a label

So just what is a Lethal White?



A pup born from a merle-to-merle mating that has inherited two merle genes

They are more correctly known as 'homozygous' or 'double merle' dogs



Science(y)-bit ...

Genes in a nutshell: 

  • a merle colour gene is dominant (M)
  • a solid colour is regressive (m)
  • a solid colour pup will have an (mm) combination
  • a pup with the (Mm) heterozgous (meaning mixed) gene will be a merle
  • but a pup with the (MM) homozygous (meaning like) gene will be a Lethal White

SO . . .

A merle gene (M) is an epistatic gene that has an effect on other colour genes

Only a merle parent can produce a merle pup

A merle (M) mating to any other colour is likely to produce merle pups in the litter

HOWEVER . . . breeding merle to merle is the only 100% statistical way of obtaining an all merle litter

That's when the problems start . . .

If the resulting merle pup carries two merle genes (MM) then there is a high probability of it having serious medical problems

  • a double-merle dog is mostly white often with fewer merle markings
  • it is likely to be deaf
  • blind or visually impaired
  • suffer form microopthalmia (undeveloped eyeballs) (small eye syndrome)
  • or it could be born with both (deaf and blind)
  • possibly have no tear ducts
  • and it is more likely to have siezures


So what's with the name?


'Lethal White' does not refer to lethal genetic that will not allow the pups to live (as I believe it can do in horses) but that these pups are often culled at birth by the breeder because the predominance of the white colour is an indication of the defects mentioned and they would not be viable to sell.

Merle pups are more in demand and often can command a higher price

BUT it's a high 'price' for the pups pay

IF they are lucky enough to be allowed to live !