{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,17]],"date-time":"2026-09-17T09:04:37Z","timestamp":1789635877445,"version":"4.0.0"},"reference-count":45,"publisher":"MDPI AG","issue":"9","license":[{"start":{"date-parts":[[2026,9,17]],"date-time":"2026-09-17T00:00:00Z","timestamp":1789603200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Vaccines"],"abstract":"<jats:p>Canine leishmaniasis (CanL), caused by Leishmania infantum, can be difficult to manage in dogs with severe clinical disease, particularly when established treatments are impractical or poorly tolerated. We report an approximately 3-year-old mixed-breed dog from Sardinia with clinically manifest CanL, anemia, thrombocytopenia, marked hyperglobulinemia, and an immunofluorescence antibody test titer of 1:4000. The dog\u2019s condition deteriorated during allopurinol treatment, with profound lethargy, vomiting, diarrhea, and complete refusal of food and water. Because escalation to combination leishmanicidal therapy (meglumine antimoniate or miltefosine) was considered clinically unsuitable in the severely debilitated patient, allopurinol monotherapy was discontinued after 18 days without clinical improvement, and one full commercial dose of the recombinant vaccine LetiFend\u00ae was administered subcutaneously off-label. No immediate adverse reaction was observed. Clinical improvement became apparent within approximately 10 days, and near-normal activity returned within three weeks. During follow-up, hematological parameters normalized and serum protein electrophoresis showed an increased albumin\/globulin ratio and a reduced gamma-globulin fraction. Domperidone was subsequently introduced as long-term immunomodulatory follow-up, and allopurinol was temporarily reintroduced after transient laboratory deterioration in 2024; the dog remained clinically healthy through July 2026. The close temporal association is clinically noteworthy but cannot establish causality. This hypothesis-generating observation supports controlled investigation of therapeutic vaccination as a potential complementary approach in canine leishmaniasis.<\/jats:p>","DOI":"10.3390\/vaccines14090818","type":"journal-article","created":{"date-parts":[[2026,9,17]],"date-time":"2026-09-17T08:03:17Z","timestamp":1789632197000},"page":"818","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Rapid Clinical Improvement Temporally Associated with Off-Label LetiFend\u00ae Vaccination in Canine Leishmaniasis: A Case Report"],"prefix":"10.3390","volume":"14","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-5340-1073","authenticated-orcid":false,"given":"Tobias","family":"Werner","sequence":"first","affiliation":[{"name":"Institute of Analytical Chemistry, Mannheim University of Applied Sciences, Paul-Wittsack-Stra\u00dfe 10, 68163 Mannheim, Germany"},{"name":"Parasitus Ex e.V., Research and Diagnostic Center for Vector-Borne Diseases, Deutzer Stra\u00dfe 64A, 53859 Niederkassel, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Marius","family":"R\u0103mnean\u0163u","sequence":"additional","affiliation":[{"name":"Small Animal Veterinary Practice Dr. Marius Ramneantu, Am Kufholz 10, 93138 Lappersdorf, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9031-6970","authenticated-orcid":false,"given":"Torsten J.","family":"Naucke","sequence":"additional","affiliation":[{"name":"Parasitus Ex e.V., Research and Diagnostic Center for Vector-Borne Diseases, Deutzer Stra\u00dfe 64A, 53859 Niederkassel, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,9,17]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"102211","DOI":"10.1016\/j.cimid.2024.102211","article-title":"Canine leishmaniosis global prevalence over the last three decades: A meta-analysis and systematic review","volume":"112","author":"Priolo","year":"2024","journal-title":"Comp. Immunol. Microbiol. Infect. Dis."},{"key":"ref_2","doi-asserted-by":"crossref","unstructured":"Morales-Yuste, M., Mart\u00edn-S\u00e1nchez, J., and Corpas-Lopez, V. (2022). Canine leishmaniasis: Update on epidemiology, diagnosis, treatment, and prevention. Vet. Sci., 9.","DOI":"10.3390\/vetsci9080387"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"86","DOI":"10.1186\/1756-3305-4-86","article-title":"LeishVet guidelines for the practical management of canine leishmaniosis","volume":"4","author":"Koutinas","year":"2011","journal-title":"Parasites Vectors"},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"463","DOI":"10.1007\/s00436-009-1404-2","article-title":"Clinical efficacy and tolerance of miltefosine in the treatment of canine leishmaniosis","volume":"105","author":"Woerly","year":"2009","journal-title":"Parasitol. Res."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"155","DOI":"10.1007\/s00436-009-1375-3","article-title":"Comparative study on the short term efficacy and adverse effects of miltefosine and meglumine antimoniate in dogs with natural leishmaniosis","volume":"105","author":"Mateo","year":"2009","journal-title":"Parasitol. Res."},{"key":"ref_6","first-page":"279","article-title":"Clinical follow-up examination after treatment of canine leishmaniasis","volume":"23","author":"Moritz","year":"1998","journal-title":"Tokai J. Exp. Clin. Med."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"532","DOI":"10.1186\/s13071-024-06617-7","article-title":"Is pancreatitis associated with meglumine antimoniate treatment for canine leishmaniosis? A multicentric prospective study","volume":"17","author":"Castro","year":"2024","journal-title":"Parasites Vectors"},{"key":"ref_8","doi-asserted-by":"crossref","unstructured":"Gizzarelli, M., Foglia Manzillo, V., Inglese, A., Montagnaro, S., and Oliva, G. (2023). Retrospective Long-Term Evaluation of Miltefosine-Allopurinol Treatment in Canine Leishmaniosis. Pathogens, 12.","DOI":"10.3390\/pathogens12070864"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"143","DOI":"10.1099\/jmm.0.46841-0","article-title":"Molecular mechanisms of antimony resistance in Leishmania","volume":"56","author":"Goyal","year":"2007","journal-title":"J. Med. Microbiol."},{"key":"ref_10","doi-asserted-by":"crossref","unstructured":"Moncada-Diaz, M.J., Rodr\u00edguez-Almonacid, C.C., Quiceno-Giraldo, E., Khuong, F.T.H., Muskus, C., and Karamysheva, Z.N. (2024). Molecular Mechanisms of Drug Resistance in Leishmania spp. Pathogens, 13.","DOI":"10.3390\/pathogens13100835"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"101783","DOI":"10.1016\/j.cimid.2022.101783","article-title":"Xanthinuria secondary to allopurinol treatment in dogs with leishmaniosis: Current perspectives of the Iberian veterinary community","volume":"83","author":"Jesus","year":"2022","journal-title":"Comp. Immunol. Microbiol. Infect. Dis."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"346","DOI":"10.1016\/j.tvjl.2010.05.025","article-title":"Long term follow-up of dogs diagnosed with leishmaniosis (clinical stage II) and treated with meglumine antimoniate and allopurinol","volume":"188","author":"Torres","year":"2011","journal-title":"Vet. J."},{"key":"ref_13","doi-asserted-by":"crossref","unstructured":"Yasur-Landau, D., Jaffe, C.L., Doron-Faigenboim, A., David, L., and Baneth, G. (2017). Induction of allopurinol resistance in Leishmania infantum isolated from dogs. PLoS Negl. Trop. Dis., 11.","DOI":"10.1371\/journal.pntd.0005910"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"506","DOI":"10.1186\/s13071-024-06583-0","article-title":"Evidence for in vivo resistance against allopurinol in a dog infected with Leishmania infantum by reduction in copy numbers of the S-adenosylmethionine synthetase (METK) gene","volume":"17","author":"Faucher","year":"2024","journal-title":"Parasites Vectors"},{"key":"ref_15","doi-asserted-by":"crossref","unstructured":"Medkour, H., Bitam, I., Laidoudi, Y., Lafri, I., Lounas, A., Hamidat, H.K., Mekroud, A., Varloud, M., Davoust, B., and Mediannikov, O. (2020). Potential of Artesunate in the treatment of visceral leishmaniasis in dogs naturally infected by Leishmania infantum: Efficacy evidence from a randomized field trial. PLoS Negl. Trop. Dis., 14.","DOI":"10.1371\/journal.pntd.0008947"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"121","DOI":"10.1007\/s11259-018-9714-4","article-title":"Effectiveness of the sesquiterpene (-)-\u03b1-bisabolol in dogs with naturally acquired canine leishmaniosis: An exploratory clinical trial","volume":"42","year":"2018","journal-title":"Vet. Res. Commun."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"525","DOI":"10.1186\/s13071-021-05030-8","article-title":"Effect of domperidone (Leisguard\u00ae) on antibody titers, inflammatory markers and creatinine in dogs with leishmaniosis and chronic kidney disease","volume":"14","author":"Cavalera","year":"2021","journal-title":"Parasites Vectors"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"397","DOI":"10.1186\/s13071-022-05537-8","article-title":"Efficacy of domperidone plus renal diet in slowing the progression of chronic kidney disease in dogs with leishmaniosis","volume":"15","author":"Cavalera","year":"2022","journal-title":"Parasites Vectors"},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"56","DOI":"10.1016\/j.prevetmed.2014.03.010","article-title":"A single-centre, open-label, controlled, randomized clinical trial to assess the preventive efficacy of a domperidone-based treatment programme against clinical canine leishmaniasis in a high prevalence area","volume":"115","author":"Homedes","year":"2014","journal-title":"Prev. Vet. Med."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"344","DOI":"10.1186\/s13071-023-05903-0","article-title":"A blinded, randomized and controlled multicenter clinical trial to assess the efficacy and safety of Leisguard\u00ae as an immunotherapeutic treatment for healthy Leishmania infantum-seropositive dogs","volume":"16","author":"Baxarias","year":"2023","journal-title":"Parasites Vectors"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"103","DOI":"10.1186\/s13071-018-2705-z","article-title":"Prevention of disease progression in Leishmania infantum-infected dogs with dietary nucleotides and active hexose correlated compound","volume":"11","author":"Segarra","year":"2018","journal-title":"Parasites Vectors"},{"key":"ref_22","doi-asserted-by":"crossref","unstructured":"Mir\u00f3, G., Segarra, S., Cer\u00f3n, J.J., Ferrer, L., Solano-Gallego, L., Montell, L., Costa, E., Teichenne, J., Marin\u00e9-Casad\u00f3, R., and GALILEI trial Group (2024). New immunomodulatory treatment protocol for canine leishmaniosis reduces parasitemia and proteinuria. PLoS Negl. Trop. Dis., 18.","DOI":"10.1371\/journal.pntd.0012712"},{"key":"ref_23","doi-asserted-by":"crossref","unstructured":"Roatt, B.M., Aguiar-Soares, R.D.d.O., Reis, L.E.S., Cardoso, J.M.d.O., Mathias, F.A.S., de Brito, R.C.F., da Silva, S.M., Gontijo, N.D.F., Ferreira, S.d.A., and Valenzuela, J.G. (2017). A Vaccine Therapy for Canine Visceral Leishmaniasis Promoted Significant Improvement of Clinical and Immune Status with Reduction in Parasite Burden. Front. Immunol., 8.","DOI":"10.3389\/fimmu.2017.00217"},{"key":"ref_24","doi-asserted-by":"crossref","unstructured":"Christodoulides, M. (2023). Vaccines for Canine Leishmaniasis. Vaccines for Neglected Pathogens: Strategies, Achievements and Challenges, Springer.","DOI":"10.1007\/978-3-031-24355-4"},{"key":"ref_25","first-page":"20163118985","article-title":"Leishmaniosis in canines: Part 1\u2014Treating and controlling infection","volume":"46","author":"Elsheikha","year":"2016","journal-title":"Vet. Times"},{"key":"ref_26","first-page":"100048","article-title":"Allopurinol therapy provides long term clinical improvement, but additional immunotherapy is required for sustained parasite clearance, in L. infantum-infected dogs","volume":"4","author":"Nascimento","year":"2019","journal-title":"Vaccine"},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"540","DOI":"10.1111\/tmi.13382","article-title":"Commercially approved vaccines for canine leishmaniosis: A review of available data on their safety and efficacy","volume":"25","author":"Velez","year":"2020","journal-title":"Trop. Med. Int. Health"},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"323","DOI":"10.25259\/IJMR_1040_2024","article-title":"An update on recombinant vaccines against leishmaniasis","volume":"160","author":"Shital","year":"2024","journal-title":"Indian J. Med. Res."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"1972","DOI":"10.1016\/j.vaccine.2018.02.111","article-title":"A large-scale field randomized trial demonstrates safety and efficacy of the vaccine LetiFend\u00ae against canine leishmaniosis","volume":"36","author":"Iniesta","year":"2018","journal-title":"Vaccine"},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1016\/S0165-2427(02)00315-X","article-title":"A Leishmania infantum multi-component antigenic protein mixed with live BCG confers protection to dogs experimentally infected with L. infantum","volume":"92","author":"Molano","year":"2003","journal-title":"Vet. Immunol. Immunopathol."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"5964","DOI":"10.1016\/j.vaccine.2009.07.069","article-title":"The chimerical multi-component Q protein from Leishmania in the absence of adjuvant protects dogs against an experimental Leishmania infantum infection","volume":"27","author":"Iniesta","year":"2009","journal-title":"Vaccine"},{"key":"ref_32","unstructured":"European Medicines Agency (2026, August 12). LetiFend\u00ae: Summary of Product Characteristics, Available online: https:\/\/www.ema.europa.eu\/en\/medicines\/veterinary\/EPAR\/letifend."},{"key":"ref_33","doi-asserted-by":"crossref","unstructured":"Leite, J.C., Gon\u00e7alves, A.A.M., de Oliveira, D.S., Resende, L.A., Boas, D.F.V., Ribeiro, H.S., Pereira, D.F.S., da Silva, A.V., Mariano, R.M.D.S., and Reis, P.C.C. (2023). Transmission-Blocking Vaccines for Canine Visceral Leishmaniasis: New Progress and Yet New Challenges. Vaccines, 11.","DOI":"10.3390\/vaccines11101565"},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"341","DOI":"10.1016\/j.pt.2010.04.005","article-title":"Immunity to Leishmania and the rational search for vaccines against canine leishmaniasis","volume":"26","author":"Reis","year":"2010","journal-title":"Trends Parasitol."},{"key":"ref_35","doi-asserted-by":"crossref","unstructured":"Digiaro, S., Recchia, A., Colella, A., Cucciniello, S., Greco, B., Buonfrate, D., and Paradies, P. (2024). Treatment of Canine Leishmaniasis with Meglumine Antimoniate: A Clinical Study of Tolerability and Efficacy. Animals, 14.","DOI":"10.3390\/ani14152244"},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"131","DOI":"10.1016\/j.rvsc.2019.08.026","article-title":"Short Term Impacts of Meglumine Antimoniate Treatment on Kidney Function in Dogs with Clinical Leishmaniosis","volume":"126","year":"2019","journal-title":"Res. Vet. Sci."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"105","DOI":"10.1016\/j.rvsc.2006.10.008","article-title":"Evaluation of Renal and Hepatic Functions in Dogs Naturally Infected by Visceral Leishmaniasis Submitted to Treatment with Meglumine Antimoniate","volume":"83","author":"Lopes","year":"2007","journal-title":"Res. Vet. Sci."},{"key":"ref_38","unstructured":"(2026, August 12). Regulation (EU) 2019\/6 of the European Parliament and of the Council of 11 December 2018 on Veterinary Medicinal Products and Repealing Directive 2001\/82\/EC. Available online: https:\/\/eur-lex.europa.eu\/eli\/reg\/2019\/6\/oj."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"1332","DOI":"10.4269\/ajtmh.17-0888","article-title":"Safety Analysis of Leishmania Vaccine Used in a Randomized Canine Vaccine\/Immunotherapy Trial","volume":"98","author":"Toepp","year":"2018","journal-title":"Am. J. Trop. Med. Hyg."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"890","DOI":"10.1016\/j.vaccine.2019.10.078","article-title":"Vaccination with LetiFend\u00ae reduces circulating immune complexes in dogs experimentally infected with L. infantum","volume":"38","author":"Parody","year":"2020","journal-title":"Vaccine"},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"431","DOI":"10.1055\/a-1970-9590","article-title":"Ein update zur leishmaniose des hundes: Diagnostik, therapie und monitoring","volume":"50","author":"Naucke","year":"2022","journal-title":"Tier\u00e4rztliche Prax. Ausg. K Kleintiere Heimtiere"},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"98","DOI":"10.1186\/s13071-025-06731-0","article-title":"Characterisation and evaluation of predisposing factors for the development of xanthinuria in dogs with leishmaniosis under allopurinol therapy","volume":"18","author":"Oliveira","year":"2025","journal-title":"Parasites Vectors"},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"747","DOI":"10.1084\/jem.20041470","article-title":"A role for IgG immune complexes during infection with the intracellular pathogen Leishmania","volume":"201","author":"Miles","year":"2005","journal-title":"J. Exp. Med."},{"key":"ref_44","doi-asserted-by":"crossref","unstructured":"Peris, M.P., Esteban-Gil, A., Ortega-Hern\u00e1ndez, P., Morales, M., Halaihel, N., and Castillo, J.A. (2021). Comparative Study of Real-Time PCR (TaqMan Probe and SYBR Green), Serological Techniques (ELISA, IFA and DAT) and Clinical Signs Evaluation, for the Diagnosis of Canine Leishmaniasis in Experimentally Infected Dogs. Microorganisms, 9.","DOI":"10.3390\/microorganisms9122627"},{"key":"ref_45","doi-asserted-by":"crossref","unstructured":"Solc\u00e0, M.S., Bastos, L.A., Guedes, C.E.S., Bordoni, M., Borja, L.S., Larangeira, D.F., da Silva Estrela Tuy, P.G., Amorim, L.D., Nascimento, E.G., and de S\u00e1 Oliveira, G.G. (2014). Evaluating the Accuracy of Molecular Diagnostic Testing for Canine Visceral Leishmaniasis Using Latent Class Analysis. PLoS ONE, 9.","DOI":"10.1371\/journal.pone.0103635"}],"container-title":["Vaccines"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2076-393X\/14\/9\/818\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,9,17]],"date-time":"2026-09-17T08:35:54Z","timestamp":1789634154000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2076-393X\/14\/9\/818"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,9,17]]},"references-count":45,"journal-issue":{"issue":"9","published-online":{"date-parts":[[2026,9]]}},"alternative-id":["vaccines14090818"],"URL":"https:\/\/doi.org\/10.3390\/vaccines14090818","relation":{},"ISSN":["2076-393X"],"issn-type":[{"value":"2076-393X","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,9,17]]}}}