Splenic Nodules: Canine Visceral leishmaniasis?

Abstract

Background: Canine visceral leishmaniasis (CVL) is a parasitic disease of high lethality caused by the protozoan Leishmania infantum in Brazil and is often related to splenomegaly. However, splenic nodules in dogs, although frequent, have not previously been reported as associated with CVL, but with neoplastic diseases. Considering that most dogs infected are oligosymptomatic or asymptomatic and that splenic nodules are common to other diseases, it is prudent to differentially diagnose CVL in view of its high zoonotic potential and lethality. The objective of the study was to describe a case of splenomegaly with splenic nodules associated with CVL in an asymptomatic dog treated with 2% miltefosina. Case: A 5-year-old male Rottweiler with 41 kg, with a history of inappetence, apathy and weight loss was referred to the Veterinary Medicine School Clinic of the Cesmac University Center, Maceió, AL, Brazil. However, during palpation a slight increase in the spleen was noted. Hematological, hemoparasite, biochemical and abdominal ultrasonographic examinations were requested to clarify the clinical suspicion of hemoparasitosis. The hematological and biochemical results respectively showed the following: normocytic normochromic anemia, hyperproteinemia and thrombocytopenia, in addition to hypoalbuminemia, with elevated total protein levels. The test for hemoparasites was negative. Ultrasonography showed mixed echogenicity suggestive of nodules. The rapid test for Ehrlichia, Anaplasma and L. infantum was performed. It was positive only for L. infantum. ELISA, IFAT and qPCR tests were performed to confirm the result. The test showed a cut-off result of 0.371 for ELISA, positive for RIFI at a cut-off of 1:40 and qPCR with less than 1 fg and with amplification above 36 cycles. In view of these results, treatment with 2% miltefosine at a dose of 1 mL/ 10 kg was started once a day, after feeding, for 28 days. The animal was monitored throughout treatment and re-evaluated every 10 days for 30 days, showing signs of clinical development, presenting satisfactory results.Discussion: Canine splenomegaly can be associated with a variety of disease possibilities. In asymptomatic canine visceral leishmaniasis (CanL), the slight increase in spleen and the presence of splenic nodules may lead to a false diagnosis. Splenic nodules may be associated with dogs of advanced age and may be due to lymphoid nodular hyperplasia, which causes nodules with echogenicity, hyperechoic regions with well demarcated irregularity, with centralized hypoechoic areas and an absence of hematological and biochemical alterations. The cause of splenomegaly associated with nodules may be difficult to diagnose and require much time and effort. Therefore, diseases such as visceral leishmaniasis of high lethality must be the priority in differential diagnosis in endemic areas in order to minimize the risk of transmission. In addition to allowing an early intervention aiming at good animal health results and preventive measures, such as the use of repellent collars that reduce the risk of phlebotomo infection. The differential diagnosis of CVL is necessary in endemic areas, even in asymptomatic dogs that may present splenic alterations suggestive of other diseases. Treatment with 2% miltefosine was shown to be, in this case, effective at reducing the splenic nodules and a good alternative for the quality of life of the animal.