Increased Parasite Resistance and Recurrent Airway Obstruction in Horses of a High-Prevalence Family
Version of Record online: 22 JAN 2010
Copyright © 2010 by the American College of Veterinary Internal Medicine
Journal of Veterinary Internal Medicine
Volume 24, Issue 2, pages 407–413, March/April 2010
How to Cite
Neuhaus, S., Bruendler, P., Frey, C.F., Gottstein, B., Doherr, M.G. and Gerber, V. (2010), Increased Parasite Resistance and Recurrent Airway Obstruction in Horses of a High-Prevalence Family. Journal of Veterinary Internal Medicine, 24: 407–413. doi: 10.1111/j.1939-1676.2009.0465.x
- Issue online: 1 MAR 2010
- Version of Record online: 22 JAN 2010
- Submitted July 9, 2009; Revised August 19, 2009; Accepted November 23, 2009.
- Hygiene hypothesis
Background: Equine recurrent airway obstruction (RAO) shares many characteristics with human asthma. In humans, an inverse relationship between susceptibility to asthma and resistance to parasites is suspected.
Hypothesis/Objectives: Members of a high-incidence RAO half-sibling family (F) shed fewer strongylid eggs compared with RAO-unaffected pasture mates (PM) and that RAO-affected horses shed fewer eggs than RAO-unaffected half-siblings.
Animals: Seventy-three F and 73 unrelated, age matched PM.
Methods: Cases and controls kept under the same management and deworming regime were examined. Each individual was classified as RAO affected or RAO unaffected and fecal samples were collected before and 1–3 weeks and 3 months after deworming. Samples were analyzed by combined sedimentation-flotation and modified McMaster methods and classified into 3 categories of 0 eggs per gram of feces (EpG), 1–100 EpG, and >100 EpG, respectively.
Results: PM compared with RAO-affected F had a 16.7 (95% confidence interval [CI]: 2.0–136.3) times higher risk for shedding > 100 EpG compared with 0 EpG and a 5.3 (95% CI: 1.0–27.4) times higher risk for shedding >100 EpG compared with 0 EpG. There was no significant effect when RAO-unaffected F were compared with their PM. RAO-unaffected compared with RAO-affected offspring had a 5.8 (95% CI: 0.0–1.0) times higher risk for shedding 1–100 EpG. Age, sex, breed, and sharing pastures with other species had no significant confounding effects.
Conclusion and Clinical Importance: RAO is associated with resistance against strongylid parasites in a high-prevalence family.