Chronic Colitis Due to Leishmania Infection in Two Dogs

Cani ne leishmani asis is a seve re, often fata l, systemic disease of the dog caused by the pro tozoan parasite Leishmania infantum. T he disease is endemic in Med iterranean countries and is occas ionally seen in North Euro pe and in the United States in dogs that have been in ende mic areas. Thi s parasite is transmi tted by sand flies of the subfamily Phlebotominae. In the dog, leishmani ds mu ltipl y inside macroph ages and ot her cells of the mononuclear-ph agocyte-system, causing chro nic inflamma tory processes. ' . 2 Classic canine leishman iasis app ears clinically as a chronic wast ing disease, with anemia, cutaneo us lesion s, and generalized lymphadenopathy. Some dogs also show epis taxis, arthritis, keratocon j unctivi tis , or uveitis. l' In the later stages of the disease, a fata l, chro nic renal failure , du e to an immune-mediated glomeru lonephritis, appears in most of the affected animals.v" In this paper , we present two cases of canine leishm ani asis in which the prima ry clin ical sign was chro nic diarrhea, a change not usua lly associated with leishman iasis. Two unrelated dogs, a I-year-old, male mo ngrel (dog No. I) and a 10-m onth-old , male Ge rma n Shepherd Dog (No. 2), were brought to the Veterinary Teac hing Hospital with chronic large bowe l diarrhea. T he result s of prelim inary labora tory tests, including parasitological examinatio n of the feces, were normal. T he dogs did not respon d to antibiotics or to metron idazol. Fina lly, the anima ls were referred for endoscopic exa mi natio n and biopsy. Both anima ls had been routinely vaccinated and had been healthy previously. Th ey had not received an y treatment with imm unos upp resive effects . T he results of the physical exami nation were norma l except for the presence of mucus and blood in the feces. Hemogram s and blood che mis tries were nor mal except for plasma proteins, which in both anima ls were clearly eleva ted: 8.2 g/d l in dog No. I and 7.9 g/dl in dog No. 2. No para sites could be found, eve n afte r multipl e fecal examinatio ns. Rad iographs of the abdomen did not reveal any ab no rmali ties . After war m-water enemas , the large bowe l was exa mined using fiberoptic equipment. T he colonic mu cosa appeared diffusely hyperemi c, with a few focal eros ions. Four forcep bio psies were obtained from eac h anima l. Histologically, the mos t evident cha nge was a severe inflammatory infiltrate mainly in the intestina l mucosa but also in the mu scularis mucosae and the submucosa (Fig. I). Most of the inflammatory cells were macrophages, altho ugh some plasm a cells, lymphocytes and polynuclear neut roph ils could be seen scattered between the macrophages . In some areas, erosions cha racte rized by the adherence of cellular deb ris to the surface were seen. Basoph ilic bod ies were seen in sma ll vac uoles in the cyto plasm of num erous macrophages and also in the intercellular spaces (Fig. 2). Leishm aniasis, which is ende mic in the cou ntry , was suspected , and a specific ind irect imm unoperoxidase stai ning on para ffi n-emb edded sectio ns was performed} T his techn ique confirmed that the basophi lic bodies were amas tigotes of Leishmania, and colitis d ue to Leishmania infec tion was diagnosed. In bot h dogs, several bone marrow examinations were made from bone marrow samples taken from the iliac crest. Marrow films were prepared in the same way as blood film s, and sta ined by the May Grtinwa ld-Giemsa meth od . Exam ina tion of the samp les revealed some parasites inside macrophages , confirming the previous diagnosis of leishmaniasis. T he owners of the two anima ls were told of the ser iousness of the d isease and that leishmaniasis is a zoo nos is. T he owners of dog No . I opted to have it euthanatize d while the owners of dog No.2 chose treatmen t. Three series of 5 injec tio ns (a total of 15) of Glucantime R (Rhone-Merieux, Lyon , France, 100 rug/kg/day, intra muscularly) were given , sepa rated by 10-day rest period s. With the last series Glucantime was give n concurre ntly at the rate of 1.5 g/day , perorally. Th e incidence of diarrhea began to dec rease slowly, and after 2 month s had ceased altogether. Thirty days after the beginning oftreatment, the dog showed a bilateral uveitis. A year after the end of treatment , the genera l hea lth of the anima l was good, defecat ion was normal, and endoscopic exa mina tio n showed norm al intestinal mu cosa. Th e uveiti s continued, but with less intensi ty. Ana lyses of blood and urine were nor ma l (total protein: 6.8 g/dl), Acco rd ing to the literatu re, chron ic large bowe l diarrhea is very uncommon as the prim ary clinical sign of canine leishmanisais. In an extensive report of 95 cases published recently, chronic diarrhea was never the primary clinica l sign. " Diarrhea has been reported in dogs affected by leishman iasis, but in these cases the affected animals showed other systemic signs, inclu ding anorexia, emaciation, anemia , lymphad enopath y, and skin lesion s. :" Inflam matory lesion s in the gastro intestinal tract assoc iated with the presence ofamas tigotes ins ide macroph ages have been report ed in dogs infected experiment ally with Leishmania amastigotes.v -' In one of the reports, the lesions and clinical signs were simi lar to those described in this paper . ' Our cases show that one of the clinical signs of canine leishmaniasis can be the presence of diarrhea du e to colitis . Th e presence of Leishma nia in the bone marrow of both dogs confirmed that in our cases the infection was syste mic. T he reason for the predominant localization of the parasites in the intestina l mucosa is unknow n. Th e clinical signs of this colitis are those of large bowel diarrh ea: increased frequency of defecat ion and low-volum e stool with tenesm us an d dyschezia . Mucus or blood or bot h are commonly seen in the feces. An inc rease in the plasma pro teins is qu ite commo n in canine leishmaniasis and was also present in our dogs . Uve itis has been descr ibed as an allergic reactio n in dogs with leishmaniasis during treatment with Glucantime R, simi lar to post-Kala-Azar leishmaniasis in human beings . " As a result of our findings, leishmaniasis should be con -