Utility of Thoracic Radiological Determinations in Ferrets Infected with Dirofilaria immitis

Abstract

The objective of this study was to evaluate the usefulness of thoracic radiography for detecting cardiac abnormalities in ferrets naturally infected with Dirofilaria immitis. Quantitative metrics adapted to the species' morphology were applied, including VHS, VRHI, TIHS, SHS, and cardiac areas (AREAPOL), to establish reliable diagnostic parameters. A prospective and descriptive study was conducted in 32 ferrets (20 males and 12 females) residing in Gran Canaria. Infection was determined using laboratorial tests (antigens, IgG antibodies, microfilariae) and transthoracic echocardiography. Radiographs were taken in right lateral, left lateral, and ventrodorsal projections without sedation, and cardiac parameters were measured using Horos® software. Statistical analysis was performed with SPSS v25, applying parametric or nonparametric tests as appropriate. Six positive and twenty six negative ferrets were identified. Cardiac area measurements (R-AREAPOL and VD-AREAPOL) were significantly larger in males (p< 0.05) and in infected animals (p < 0.05). Significant differences were also found between infected and uninfected ferrets in R-VHS, R-VRHI, and L-SHS. Some metrics, such as TIHS and VD-VRHI, showed more stable and non-significant values between groups. Thoracic radiography, without the need for sedation, proved to be a viable and useful tool for detecting cardiovascular abnormalities in ferrets with heartworm disease. The measurements of R-VHS, R-VRHI, L-SHS, and especially R-AREAPOL and VDAREAPOL were able to differentiate infected from healthy animals. The results suggest the need to establish sex-differentiated reference values and conduct larger studies to validate diagnostic cutoff points applicable in endemic areas.