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.