Diagnosis and therapeutic management of Babesia gibsoni-induced paraplegia in dogs

Introduction

Canine Babesia species are intraerythrocytic protozoan parasites classified under the order Piroplasmida of the phylum Apicomplexa (Schnittger et al., 2012; Koster et al., 2015) [16,13] . They are morphologically categorized into large forms (Babesia canis), and small forms (Babesia gibsoni). Transmission occurs primarily through ixodid ticks, with Haemaphysalis spp. recognized as the principal vectors of B. gibsoni in dogs (Irwin, 2009; Jongejan et al., 2018) [9,11] . In India, B. canis and B. gibsoni are the predominant causative agents of canine babesiosis (Jain et al., 2017; Baneth, 2018) [10,1] . The clinical manifestations of canine babesiosis vary from mild to severe systemic illness. Common signs include anorexia, pyrexia, vomiting, pallor of mucous membranes, tachycardia, and polypnea. However, atypical and severe complications such as ascites and neurological deficits, including paraplegia, have also been reported, indicating the potential for multisystem involvement (Gonde et al., 2016) [5] . Neurological manifestations, although uncommon, are clinically significant and may arise due to hypoxia, vascular compromise, or immune-mediated mechanisms affecting the central nervous system. Accurate diagnosis of babesiosis involves a combination of clinical evaluation and laboratory techniques, including microscopic examination of blood smears, complete blood count analysis, serological testing such as the SNAP 4Dx test, and molecular methods like polymerase chain reaction (PCR) (Daviktov et al., 2015) [6] . Additionally, immunochromatographic tests utilizing recombinant antigens have been developed for rapid and specific detection of B. gibsoni antibodies (Verdida et al., 2005) [20] . The conventional treatment of canine babesiosis involves antiprotozoal agents such as imidocarb dipropionate and diminazene aceturate; however, these drugs often exhibit limited efficacy against Babesia gibsoni, highlighting the need for alternative therapies (Teodorowski et al., 2022) [18] . Artesunate, a potent semisynthetic derivative of artemisinin, has shown promise due to its antiparasitic activity, which includes the generation of reactive free radicals, inhibition of heme polymerization, and disruption of parasite membrane transport, ultimately leading to parasite death. Studies have reported that oral administration of artesunate at 12.5 mg/kg once daily for 10 days is effective in treating B. gibsoni infection in dogs (Goo et al., 2010; Karasová et al., 2022; and Bhasme et al., 2024) [7,18,2] .

Materials and Methods

Two cases, from different time periods, were examined, and both dogs exhibited similar clinical histories, including lethargy, acute paraplegia, fever, inappetence, and 2-3 episodes of vomiting, upon presentation at VCC, PGIVAS, Akola. Clinical examination revealed congested CMM, tick infestation and swollen lymph nodes, Ashok as shown in Figures 1 and2. Clinico-physiological parameters were systematically recorded on day 0 (pre-treatment) and subsequently on the 10th and 30th days post-treatment. These included rectal temperature (°F), respiratory rate (breaths per minute), heart rate (beats per minute), capillary mucous membrane (CMM) status, capillary refill time (CRT, seconds), and body weight (kg). Blood samples were collected for diagnosis, and haematobiochemical investigations were performed on day 0 (pre-treatment) and on the 10th and 30th days post-treatment. The parameters evaluated included haemoglobin (Hb, g/dl), total erythrocyte count (TEC, ×10⁶ /cu.mm), packed cell volume (PCV, %), platelet count (×10⁵ /µl), total leukocyte count (TLC, ×10³/cu.mm), and absolute neutrophil count (×10³/cu.mm). Biochemical parameters included total protein (g/dl), liver enzymes ALT/SGPT (IU/L) and AST/SGOT (IU/L), renal markers included blood urea nitrogen (BUN, mg/dl) and creatinine (mg/dl), and the iron metabolism indicator total iron-binding capacity (TIBC, µg/dl). Diagnosis of Babesia gibsoni infection had been carried out using blood smear examination and the antibody rapid test (ICT), which were performed on day 0 (pre-treatment) and on the 10th and 30th days post-treatment for direct parasite detection and serological screening, while PCR targeting the cox3 gene was conducted on day 0 (pre-treatment) and day 30 th (post-treatment) to confirm infection and monitor parasite clearance.

Diagnosis

The diagnosis of the infection was carried out using blood smear examination, the rapid antibody test (ICT), and PCR. The results are summarized in Table 1 and illustrated in Figures 345. Positive samples.

Treatment

Both dogs were treated with artesunate at a dose of 12.5 mg/kg orally once daily and azithromycin at 10 mg/kg orally once daily for 10 days. In addition to specific therapy, supportive treatment was provided on the day of admission, which included antipyretics (inj. meloxicam @ 0.2 mg/kg, IM) and antiemetics (inj. Ondansetron @ 0.2 mg/kg, IM). Neurotropic vitamin therapy containing mecobalamin (1500 µg/dog, IM) and inj. Methylprednisolone acetate (120 mg/dog, IM) was administered on days 0, 3, and 7 to support neural repair and to reduce neuropathic pain and inflammation associated with Babesia gibsoni-induced paraplegia. Polyherbal liver and platelet stimulants were also administered orally to manage systemic complications and support recovery. Owners of both the dogs were advised to present the patients for follow-up examinations on the 10th and 30th days posttreatment. Additionally, owners were also instructed to assist their dogs with physical activity like walking with weightbearing support during the early stages of recovery to ensure safe ambulation and to prevent injury.

Results and Discussion

Canine babesiosis commonly presents with clinical signs such as fever, lethargy, anorexia, and enlargement of lymph nodes and the spleen (Boozer and Macintire, 2003) [3] . Occasionally, it has also been reported to manifest as paraplegia (Gonde, 2016) [5] .

The clinical parameters of both dogs over the treatment period are summarized in table 2. The elevated body temperature in the dogs was caused by infection-induced inflammation and vascular damage (Zygner et al., 2023) [21] , and he also stated that babesiosis can cause hemodynamic instability, hypovolemia, and microvascular obstruction due to red blood cell sequestration which causes prolonged CRT. [4] , is caused by splenic sequestration and immune-mediated platelet destruction.

Leukocytosis in naturally infected babesiosis cases is often associated with neutrophilia and secondary bacterial infections (Gurjar et al., 2023 and Sivajothi et al., 2014) [8,17] . Neutrophilia serves as a primary defense mechanism against piroplasm infection (Mittal et al., 2019) [15] . The increase in AST without a marked ALT rise suggests an extra-hepatic origin (Thomas, 2000; Koseoglu et al., 2011) [19,12] . The finding of normal serum creatinine with elevated BUN indicated prerenal azotemia; an increased urea-to-creatinine ratio with normal creatinine is typically of non-renal origin (Lobetti et al., 2012) [14] . The clinical and hematobiochemical improvements observed indicate successful recovery following treatment. [2] .

Acknowledgement

Conflict of InterestThe authors declare that they have no conflicts of interest. AcknowledgmentThe authors sincerely thank the faculty members of the Departments of Veterinary Medicine, Veterinary Pathology, and the Veterinary Clinical Complex (VCC), as well as the Dean of the Post Graduate Institute of Veterinary and Animal Sciences (PGIVAS), Akola, Maharashtra, for providing the necessary facilities and support.

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