Leishmaniases are zoonoses caused by protozoa of the genus Leishmania, with significant impact
on public health. The disease can occur in tegumentary or visceral form, depending on the
Leishmania species, and transmission is through the bite of female sandflies of the family
Psychodidae, commonly known as phlebotomine sandflies. In the Americas, Brazil concentrates
the majority of reported cases of both forms. Domestic and wild felines are hosts of the protozoa
species that are most incident in Brazil, with reports of infected cats mainly in areas of intense
disease transmission. Despite being considered more resistant, infected felines may present
cutaneous alterations in tegumentary leishmaniasis and alterations in different organs such as skin,
liver, spleen, lymph nodes, and lungs in visceral leishmaniasis. Histopathological analysis is a
diagnostic method that can aid in understanding the damage caused to the host, and few
histopathological studies have been conducted in naturally parasitized domestic felines to date.
This study aimed to evaluate the application of different staining methods in the analysis of
cutaneous tissue of naturally parasitized domestic felines by Leishmania amazonensis and report
the renal alterations caused by Leishmania infantum infection in cats. For the analyses, samples of
cutaneous nodules from a cat positive for L. amazonensis were collected and subjected to
histological processing, followed by staining with hematoxylin-eosin (HE), periodic acid-Schiff
(PAS), Fontana-Masson, fast green, and Mallory's trichrome, and the staining quality was
evaluated. Samples of kidneys from 5 cats positive for L. infantum and 5 negative cats were stained
with HE and PAS and were analyzed and compared. Among the stains analyzed in cutaneous
nodular tissue, hematoxylin and eosin staining showed better performance for visualizing the
protozoa and tissue components. The other stains, although not yielding the same result as
hematoxylin and eosin, still managed to reveal the parasite in the tissue, albeit more difficultly.
Renal alterations were observed in 100% of positive and negative cats. The most frequent
glomerular alteration was membranous glomerulonephritis, present in all negative animals and
80% of positive animals, but with different intensity grades (P<0.05). Positive animals for
Leishmania presented interstitial nephritis, which was not found in negative cats (P<0.05). The
results obtained show that hematoxylin and eosin staining was the best staining method for
visualizing Leishmania and skin tissue aspects. Additionally, it was evidenced that cats also
develop visceral lesions of leishmaniasis, as demonstrated in this study by the significant
occurrence of renal lesions.
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