Question submitted during the Underlying Disease Screening in Dogs with IMHA webinar:
Why is it that Cocker Spaniels are the "poster dogs" for this disease?
Please see the answer to the question about genetics.
Its likely that Cocker spaniels have an overall “genetic burden” that predisposes them to being very cute and also having a propensity to developing immune mediated disease. There have been a few studies that have looked at Cocker spaniels with and without a history of IMHA but those studies are difficult because we don’t know if the ones without IMHA at the time of the study will develop it in the future and they just haven’t had the “trigger” exposure to instigate the disease. It appears that the diversity of genes that code for a family of molecules that present foreign antigen to the immune system and another that down regulates the immune response is limited in cocker spaniels. (Trelfall AJ et al. Analysis of DLA-DQB1 and polymorphisms in CTLA4 in Cocker spaniels affected with immune-mediated haemolytic anaemia.) More studies are needed to determine if genetics will determine which ones get it and how many genes are involved and if epigenetics and environment play a role. Note that studies of twins show some develop immune mediated disease and some don’t, so its not all genes.
