Hematologic and bone marrow changes in dogs experimentally infected withRangelia vitalii

Piroplasmid Infections Among Domestic Dogs in the Mountain City of Rio de Janeiro, Brazil

PURPOSE

The aim of the present study was to analyze the frequency of the piroplasmids in blood from dogs and ticks recovered from these animals in Teresópolis city, located in the mountain region of Rio de Janeiro state, Brazil. In addition to the clinical and hematological profile.

METHODS

A total of 400 dogs attended in a veterinary clinic in this city between 2020 and 2021 were included. The blood was collected from the dogs, along with ticks and information on these dogs was obtained through a questionnaire applied to the owners. Thin-smear analyses and complete blood counts were performed. All forms characteristic of piroplasmids were measured and classified morphologically. The blood was also subjected to PCR assays based on the genes 18S rRNA and hsp70. In addition, the ixodid ticks were classified morphologically and subjected to PCR for piroplasmids research. The amplified products were sent for gene sequencing.

RESULTS

Piroplasmids were detected in 2.3% of the dogs. The variables statistically associated with infections in these animals were hemorrhage/bleeding, jaundice, anisocytosis, activated monocytes and macroplatelets (p ≤ 0.05). Piriform, ring-shaped, oval and aberrant structures were viewed in erythrocytes, neutrophils and monocytes, with lengths greater than and less than 2.5 µm. The nine positive samples from these dogs were characterized as due to Rangelia vitalii. However, one sequence from B. vogeli was detected in a single adult specimen of R. sanguineus.

CONCLUSION

Although circulation of two species of piroplasmids potentially infective for domestic dogs has been observed in the mountain city of Rio de Janeiro, infection due to R. vitalii was mostly seen in the dogs of the present study.

ACVIM consensus statement on the diagnosis of immune-mediated hemolytic anemia in dogs and cats

Immune-mediated hemolytic anemia (IMHA) is an important cause of morbidity and mortality in dogs. IMHA also occurs in cats, although less commonly. IMHA is considered secondary when it can be attributed to an underlying disease, and as primary (idiopathic) if no cause is found. Eliminating diseases that cause IMHA may attenuate or stop immune-mediated erythrocyte destruction, and adverse consequences of long-term immunosuppressive treatment can be avoided. Infections, cancer, drugs, vaccines, and inflammatory processes may be underlying causes of IMHA. Evidence for these comorbidities has not been systematically evaluated, rendering evidence-based decisions difficult. We identified and extracted data from studies published in the veterinary literature and developed a novel tool for evaluation of evidence quality, using it to assess study design, diagnostic criteria for IMHA, comorbidities, and causality. Succinct evidence summary statements were written, along with screening recommendations. Statements were refined by conducting 3 iterations of Delphi review with panel and task force members. Commentary was solicited from several professional bodies to maximize clinical applicability before the recommendations were submitted. The resulting document is intended to provide clinical guidelines for diagnosis of, and underlying disease screening for, IMHA in dogs and cats. These should be implemented with consideration of animal, owner, and geographical factors.

Surface immunoglobulins of erythrocytes and platelets in dogs naturally infected by Rangelia vitalii

Rangelia vitalii is a protozoan of the Babesiidae family that parasitizes domestic and wild dogs in South American countries. The main laboratory findings in blood samples from animals infected by R. vitalii are anemia and thrombocytopenia. The aim of this study was to detect IgM and IgG immunoglobulins on the surface of red blood cells and platelets, as well as to determine the percentage of reticulated platelets and reticulocytes in dogs naturally infected by R. vitalii. Blood samples from twenty dogs seen at the Veterinary Hospital of the Federal University of Santa Maria (UFSM) were divided into two groups: the diseased group consisted of blood samples from 10 animals with the diagnosis of rangeliosis, and the healthy group (control) consisted of samples from 10 healthy animals. All diseased dogs showed normocytic normochromic anemia but showed no differences (p > 0.05) in reticulocyte counts compared to healthy dogs. Moreover, IgM and IgG immunoglobulins were detected on the surface of the plasma membrane of red blood cells from both groups, but the amounts did not differ between groups (p > 0.05). Thrombocytopenia in infected animals was classified as severe. The percentage of reticulated platelets was higher (p < 0.001) in diseased dogs than in healthy animals. Diseased animals showed more IgM immunoglobulins bound to the surface of platelets than did the healthy group (p < 0.001). However, the amount of IgG bound to the surface of platelets was not different between groups. In conclusion, we showed that R. vitalii caused immune-mediated thrombocytopenia since IgM immunoglobulins were found on the surface of platelets of diseased dogs. We suggest that the binding of immunoglobulins on platelet surfaces contributes to early destruction of these cells and, consequently, alterations in hemostasis. An increase in reticulated platelets was noted in response to thrombocytopenia, indicating active thrombopoiesis.

Clinical and hematological evaluation of Rangelia vitalii-naturally infected dogs in southeastern Brazil

Abstract Rangelia vitalii, a tick-borne piroplasm that infects dogs, has been recently molecularly characterized in Brazil, Uruguay and Argentina. Studies on molecular characterization of these piroplasms in different Brazilian regions are scarce. The aim of this study was to evaluate clinical and hematological changes in dogs caused by R. vitalii in the mountainous region of the state of Rio de Janeiro. Blood samples from 36 dogs were evaluated for piroplasms and hematological disorders using light microscopy and molecular analysis. Blood samples from all the animals included in this study were confirmed to be positive for R. vitalii through genetic sequencing. Clinical signspresented by 24 of the 36 dogs of the study were evaluated during appointments or hospitalization within private practice. The most frequent clinical disorders in these dogs that were naturally infected with R. vitalii were fever, spontaneous cutaneous bleeding and diarrhea. Normochromic non-regenerative anemia and thrombocytopenia were the most common hematological disorders in these R. vitalii-positive dogs and therefore should be considered in hematological evaluations on suspected cases.

Rangelia vitalii in a free-ranging maned wolf (Chrysocyon brachyurus) and co-infections

An adult free-ranged female maned wolf was rescued from a periurban area subject to anthropogenic disturbances in the Minas Gerais, Brazil. The animal presented poor body condition and anemia. The clinical condition rapidly deteriorated culminating in dead and a necropsy was performed. The main gross lesions were marked anemia and blood content in the intestines accompanied by many types of parasites. The protozoa Rangelia vitalii was identified by histopathological analysis predominantly within the cytoplasm of endothelial cells of capillaries of the small intestine. The lymph nodes, spleen, bone marrow, dermis, lungs and kidney had similar protozoal forms but with mild or moderate intensity. Rangelia vitalii was confirmed by molecular assays. Hepatozoon sp., Leishmania sp., and Entamoeba spp., apparently not related to the clinical signs were also detected. The myriad parasites found in the intestines included nematodes (Ancylostoma caninum, A. braziliensis,, Molineus sp., Pterygodermatites sp., and Trichuris sp.), cestodes (Spirometra sp.) and (acanthocephalans. To our knowledge, R. vitalii was identified in C. brachyurus for the first time. These findings emphasize the fragility of Brazilian ecosystems, especially in disturbed areas, reinforcing the necessity of efforts to preserve these areas and wild carnivores, some of which are threatened with extinction, such as the maned wolf.

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Rangelia vitalii was found in Chrysocyon brachyurus, especially in small intestine.

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Co-infections with other parasites were found, including some with zoonotic potential.

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Anemia was likely linked to R. vitalii, Ancylostoma spp and perhaps Spirometra.

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Health status of the near threatened maned wolf reflects anthropogenic disturbed of habitat.

Adenosine levels in serum and adenosine deaminase activity in blood cells of dogs infected by Rangelia vitalii

Ecto-adenosinedeaminase (E-ADA) plays an important role in the production and differentiation of blood cells as well as in the control of extracellular adenosine levels. Infectious diseases can influence the synthesis of new cells or cause cell destruction, as occurs in canine rangeliosis, which results in anemia, thrombocytopenia, leukocytosis, and/or leukopenia. Thus, this study aimed to evaluate E-ADA activity in sera, erythrocytes, lymphocytes, and adenosine levels in sera samples of dogs infected by Rangelia vitalii. Twelve animals were divided into 2 groups: noninfected (n = 5) and infected by R. vitalii (n = 7). Animals were infected with 2 ml of blood containing the parasite, and parasitemia was estimated daily for 20 days by microscopic examination of peripheral blood smears. Blood collection was performed on days 0, 10, and 20 post-infection (PI) in order to evaluate the evolution of the disease. The blood collected was used to assess the activity of E-ADA. We observed an increase of E-ADA activity in sera (day 20 PI) and erythrocytes (days 10 and 20 PI) in the infected group (P < 0.05). E-ADA activity in lymphocytes was decreased on day 10, when the parasitemia was high, and increased after 20 days, when the number of circulating parasites was low. HPLC measured adenosine levels in the serum and found a reduction on days 10 and 20 PI. In conclusion, our results showed that E-ADA activity was altered in sera, lymphocytes, and erythrocytes of dogs experimentally infected by R. vitalii as well as the serum concentration of adenosine. These alterations may contribute to the pathogenesis of anemia and immune response in infected dogs.