Question submitted during the Underlying Disease Screening in Dogs with IMHA webinar:
Do you believe vaccinations and/or Frontline and/or Heartgard application, combined with a bitch having been in season (or not in season), can contribute to the likelihood of a dog getting IMHA?
There is evidence that tick and flea borne diseases and heartworm are associated with IMHA or anemias with antibody on the red cell surface, as reviewed in the lecture and in the upcoming ACVIM consensus statement. So preventing them is important. It's worthy of noting that because these preventative medications are given monthly usually it would be difficult to figure out if an association (within 30 days) existed for drugs that prevent vector borne disease. Reproductive status may play a role in immune-mediated disease (see below) but to my knowledge whether an intact dog is in season or not has an impact on the development of IMHA has not been investigated. One study showed evidence that vaccination within 30 days was associated with IMHA in some patients, while another study did not show this. It is theoretically possible that vaccination in individual patients might trigger immune-mediated disease. More studies are needed to determine which factors in an individual patient might contribute to its development. Its also possible that a build up of several factors in a predisposed individual may lead to an immune “milieu” that contributes to the development of IMHA in an individual patient with say, a genetic predisposition but we just don’t know. The evidence for whether vaccination and drugs such as flea and tick preventatives are associated with IMHA in dogs is summarized in the upcoming ACVIM consensus statement.
