Etiology and pathogenesis of leptospirosis: general patterns and features of manifestation in dogs (review)

Abstract

Introduction . Leptospirosis is an infectious disease hazardous to both humans and animals. Dogs serve as a key link in transmitting the infection to humans. Within the Russian Federation, the Canicola and Icterohaemorrhagiae serogroups are of primary relevance for dogs as the most virulent ones, although infection with other Leptospira spp. serogroups remains possible. The severity of the disease is determined by the pathogenicity factors of leptospires. Due to the zoonotic nature of leptospirosis, canine vaccination is a vital element of sanitary and epidemiological freedom. Regular immunization reduces the risk of human infection and prevents outbreaks. When selecting vaccines, the limited cross-protection between serogroups should be considered, with polyvalent products being preferred. However, existing vaccines do not provide reliable protection due to outdated serogroup compositions. The persistence of the causative agent within the animal host and its shedding into the environment diminish the effectiveness of prevention. A comprehensive approach is required to prevent canine infection and subsequent causative agent transmission to humans. Objective . To update and systemize data on canine leptospirosis caused by Leptospira interrogans. Materials and methods . Scientific publications by foreign and domestic authors available in bibliographic databases such as eLibrary, CyberLeninka, PubMed, Science Direct, Google Scholar, and others served as the material for this analytical study. Results . This analytical review presents up-to-date data on the epizootic and epidemiological situation regarding leptospirosis in the Russian Federation. It examines the properties of the causative agent, presents the classification of leptospires, and describes the clinical and post-mortem lesions of the disease. Furthermore, the review characterizes modern methods of laboratory diagnosis, treatment, and prevention of canine leptospirosis currently applied in veterinary practice, and outlines existing challenges. Conclusion . Leptospirosis is widespread in dogs. Leptospires are capable of adapting and persisting in the host organism, causing a chronic course of the disease, which poses a threat to human and animal health. The complexity of pathogenesis, the diversity of serotypes and intracellular persistence complicate the eradication of the causative agent. Current diagnostic and treatment methods require improvement. Research is needed to develop effective prevention and therapy protocols, including new approaches to specific prevention in dogs. Thus, leptospirosis remains a pressing issue in veterinary medicine requiring a comprehensive approach.