Abstract
Background: Epizootic lymphangitis (EEL) is a persistent fungal disease affecting equines, yet effective vaccines remain scarce. The newly developed Histoplasma farciminosum ‘8ZH’ vaccine requires safety validation before going into general usage. Objectives: This study aimed to evaluate the biochemical and haematological safety of the H. farcimino sum ‘8ZH’ vaccine in foals. Study Design: A controlled, single-blinded trial was conducted using 30 clinically healthy foals, randomly divided into vaccinated (n = 15) and control (n = 15) groups. Methods: Foals in the vaccinated group received a 5 mL intramuscular dose of the H. farciminosum ‘8ZH’ vaccine (2 mg/mL, total 10 mg) with a booster on Day 21. Biochemical (AST, ALT, bilirubin, creatinine, glucose, cholesterol) and haematological (WBC, RBC, haemoglobin, haematocrit) parameters were measured at baseline and at multiple time points over 42 days. Results: No severe adverse effects were observed. AST levels showed a transient increase on Days 14–21 ( p = 0.04) before returning to baseline. WBC counts peaked on Day 14 ( p = 0.03) but stabilized afterward. All measured biochemical and haematological parameters remained within physiological ranges throughout the study. Conclusions: The H. farciminosum ‘8ZH’ vaccine demonstrated a favourable safety profile in foals, with no significant biochemical or haematological disturbances. These findings support its potential integration into EEL control programs, though further long-term studies are planned.