Gastrointestinal and hepatic endoparasites of domestic guinea pigs (Cavia porcellus (Linnaeus, 1758)): Diversity, diagnosis, epidemiology, and clinical relevance.

The guinea pig (Cavia porcellus (Linnaeus, 1758)) is a popular companion animal and an important laboratory model. Gastrointestinal and hepatic endoparasites are documented in this host across companion, laboratory and production settings, but the available evidence is methodologically heterogeneous and should be interpreted at study level. This structured narrative review summarizes parasite diversity, host-specific clinical evidence, diagnostic approaches and epidemiological findings. Particular emphasis is placed on separating parasite detection from infection intensity and attributable clinical disease, and on avoiding zoonotic inference without species-, genotype- or assemblage-level evidence. Across the reviewed literature, Paraspidodera uncinata and Eimeria spp. are recurrent findings, while molecular studies have refined interpretation of Cryptosporidium, Giardia and Balantioides. A source-level audit of epidemiological studies highlights substantial variation in analysis units and diagnostic methods, including pooled farm samples, individual fecal samples, post-mortem examinations and molecular assays. These differences preclude direct regional prevalence comparisons. Future studies should report explicit numerators, denominators, units of analysis, diagnostic endpoints and molecular resolution to improve comparability and One Health interpretation.