# A case report of acute claudication due to vena cava thromboembolism in a dog naturally infected with Leishmania Infantum

## TL;DR

A dog infected with Leishmania infantum developed a severe blood clot in its vena cava, likely due to immune system overactivity.

## Contribution

This case report highlights thromboembolism as a rare but severe complication of canine leishmaniosis linked to immune complex formation.

## Key findings

- A dog with leishmaniosis developed acute claudication and a massive venous thrombus in the caudal vena cava and external iliac veins.
- High levels of circulating immunocomplexes were detected, suggesting immune-mediated mechanisms contributed to thrombosis.
- Kidney and liver damage may have worsened the imbalance in hemostasis in this dog.

## Abstract

Canine leishmaniosis is a vector-borne disease caused by Leishmania infantum, and clinical manifestations of infection range from absent or severe to fatal and result from immune-mediated mechanisms. In dogs, the most common clinical signs of leishmaniosis include skin lesions and lymphadenomegaly. However, the presence of other nontypical signs has been described, and diagnosing these cases can be challenging. The aim of the present short communication was to describe the impact of the formation of circulating immunocomplexes due to L. infantum in a dog with leishmaniosis affected by a massive venous thrombus of the caudal vena cava and external iliac veins. On admission, the dog presented bilateral cutaneous vasculopathy of the thigh and renal disease due to L. infantum infection. Two weeks after starting anti-Leishmania treatment based on meglumine antimoniate and allopurinol administration, the animal developed acute claudication of the hind limbs with the presence of a thrombus in the caudal vena cava and the external iliac veins and a high level of circulating immunocomplexes detected by enzyme-linked immunosorbent assay. Exacerbation of the humoral immune response, along with deposition of circulating immune complexes in the tissues and the concurrent presence of kidney and liver damage, might have contributed to an imbalance in haemostasis in this patient. Future studies should evaluate and analyse the pathological mechanisms contributing to thrombosis in dogs with leishmaniosis.

The online version contains supplementary material available at 10.1007/s11259-024-10370-8.