Larval cyathostominosis: Clinicopathological data and treatment outcomes of 38 hospitalised horses (2009-2020)

Background: There is limited evidence regarding the treatment and outcomes of larval cyathostominosis. Objectives: To describe the presentation, treatment and outcomes of horses with larval cyathostominosis in two equine hospitals. Study design: Retrospective, multicentred cohort study. Methods: Clinical records were reviewed (2009-2020). Inclusion criteria included a diagnosis of larval cyathostominosis (determined by faecal assessment and/or post-mortem examination). Data were assessed for normality. Descriptive analysis was performed for frequency results and central tendencies. Statistical analysis between survivors and nonsurvivors was determined by Chi-square/Fisher's exact test for categorical variables, and Student's t-test/Mann-Whitney for continuous variables. Results: Of 38 cases, 21 (55%) were nonsurvivors (3/38 dead on arrival). Nonsurvivors died by 2.9 days +/- 2.4. Tachycardia (mean 61 beats/min +/- 14), leucocytosis (mean 17.1 x 10(9)/L +/- 9.1), neutrophilia (mean 14.1 x 10(9)/L +/- 8.5), hypoalbuminaemia (mean 21.6 g/L +/- 6.0), hyperfibrinogenaemia (mean 7.4 g/L +/- 2.6) and elevated serum amyloid A (SAA) (median 315.0 mg/L, interquartile range [IQR] 117.0-1460.0) were consistent findings. Faecal shedding of Salmonella spp. occurred in four cases. The mean last recorded albumin was 18.6 g/L +/- 4.5 and total protein (TP) 52.3 g/L +/- 13.6. Crystalloids were administered in 25/35, synthetic colloids in 5/35 and plasma in 17/35 cases. Anthelmintic treatment was administered in 25/35 cases, of which 22 also received corticosteroids. Recumbency prior to admission (p = 0.037) and administration of isotonic fluid therapy (p = 0.027) were associated with nonsurvival. From peripheral blood analysis, lower TP (p = 0.006) and higher SAA (p = 0.050) concentrations at admission as well as lower last recorded TP (p = 0.002) and lower last recorded albumin concentrations (p = 0.028) were associated with nonsurvival. Main limitations: Results may not be applicable to other populations. Conclusions: Referred cases of larval cyathostominosis have a low survival rate. Several variables are associated with reduced survival: history of recumbency, isotonic fluid therapy, elevated SAA at admission, low TP at admission, low last recorded TP and low last recorded albumin.