Canine parvovirus (CPV) is a devastating disease; left untreated, the mortality rate is >90%, and the high cost of aggressive treatment and prolonged hospitalization may lead to humane euthanasia. Signs of CPV infection include severe dehydration, disseminated intravascular coagulation (DIC), and bacterial translocation with sepsis. Many treatments to help decrease hospital time have been investigated, but none has led to substantial improvements in outcome. One proposed treatment is the use of passive immunotherapy with CPV-immune plasma from patients with high titers of anti-CPV antibodies. Antibodies would theoretically neutralize free virus in plasma, impede viral spread, and suppress release of new infectious virions.
This clinical trial compared neutrophil and monocyte counts, magnitude of viremia, percentage weight change, number of hospitalization days, and cost of treatment between patients treated with CPV-immune plasma (n = 7) and a placebo group (n = 7). The results suggested no benefit in offering 12 mL of CPV-immune plasma to patients within 24 hours of onset of signs. Failure to detect effects may have resulted from the small sample size or lack of recommendations as to effective dosing of CPV-immune plasma; the dose administered may have been too low to effectively neutralize CPV in the circulation or tissues.
This study did not show clinical improvement by common measures (blood work, days of hospitalization), but it did highlight several key points in the rationale for treating a patient with immunotherapy, such as its effectiveness in other diseases (tetanus, Clostridium difficile infections). Documentation of immunotherapy in other cases of viral infections was not mentioned. CPV-immune plasma may offer other therapeutic effects at proper doses, as plasma is used to treat DIC secondary to severe CPV infection and does offer potentially beneficial antiinflammatory properties. Before this therapy can be considered ineffective, more studies with larger numbers of dogs or dosing variables (onset of administration, dose, frequency) or in vitro studies documenting viral neutralization from immunotherapy are warranted.—Heather Troyer, DVM, DABVP, CVA
Clinical evaluation of a single dose of immune plasma for treatment of canine parvovirus infection. Bragg RF, Duffy AL, DeCecco FA, et al. JAVMA 240:700-704, 2012.