Farm Animals

Cattle Bovine Leukocyte Adhesion Deficiency Welfare

Bovine Leukocyte Adhesion Deficiency (BLAD) is a genetic disease causing severe immunodeficiency and early death in homozygous Holstein calves, controllable through carrier testing in bulls.

Key Facts

BLAD is caused by a recessive mutation in the CD18 gene affecting leukocyte function
Homozygous calves develop recurrent severe infections and die before 18 months of age
Carrier bulls spread the allele widely before the mutation was identified in the 1980s
DNA testing identifies carrier bulls and cows enabling breeding decisions to eliminate the condition
BLAD prevalence has decreased significantly in Holstein populations through testing programmes

Welfare Considerations

BLAD-affected calves suffer recurrent severe infections throughout their short lives. Carrier testing in breeding programmes has effectively reduced this preventable welfare burden.

What You Can Do

Support mandatory DNA testing for BLAD in Holstein bull licence approvals
Advocate for carrier status transparency in bull catalogues
Test breeding females in herds with historic BLAD exposure
Raise awareness of BLAD as an example of how genetic testing prevents inherited welfare problems