INTRODUCTION
Babesiosis is a tick-borne infection caused by several parasitic hematoprotozoal organisms belonging to the Babesia genus. Several pathogenic species have been documented in dogs, but in the United States, B. canis and B. gibsoni are most common.1-3 Transmission occurs through a variety of mechanisms, such as the bite of an infected Rhiphecephalus sanguineus tick, transplacental and direct blood-blood contact, dog bites, and contaminated blood transfusion.1 A variety of clinical syndromes in dogs and people with babesiosis have been described, and the hallmark is hemolytic anemia or “uncomplicated babesiosis.”1 Immune-mediated hemolysis, increased erythrocyte osmotic fragility, direct cellular injury by piroplasms, and oxidative injury have all been proposed as causes of hemolysis.1
In addition to anemia, other severe clinical syndromes have been described in people and dogs.4-7 Sequelae of babesiosis unrelated to hemolysis are termed “complicated babesiosis,” and are associated with worse prognosis.4 There are no consensus definitions of complicated vs. uncomplicated babesiosis in veterinary medicine, but complicated infections may include sequelae like pancreatitis, acute kidney injury, cerebral babesiosis, or hepatopathy.
Babesia -induced acute respiratory distress syndrome (ARDS) is a late and rare complication of human babesiosis cases, first reported in 1984 as a single case report5 and not again until 1994.6 The incidence of Babesia -induced ARDS in dogs is unknown, partially because case reports documenting respiratory distress in this population do not report diagnostic information to evaluate for ARDS criteria. However, several studies have shown poor outcome in dogs with complicated babesiosis that include respiratory signs, as well as histologic evidence of ARDS in a dog with cerebral babesiosis.4,8,9 The successful management of severe respiratory failure and suspected ARDS in a dog with naturally occurring babesiosis has not previously been described.