Atypical guttural pouch empyema in Arabian foals

It has been long recognized that some lines of Arab foals are predisposed to guttural pouch tympany. In this report the problem goes one step further with aspiration of milk into the GP and a secondary bacterial infection which in some cases extended to the lungs. Endoscopy was required for diagnosis and treatment required the inclusion of lavage but the prognosis was excellent.
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A control study of atypical guttural pouch empyema in Arabian foals

Vet Med Sci. 2023 Jul;9(4):1599-1609.
Authors
Nicole van der Vossen 1 , Paulo Cavalcante 2 , Sarah Glynn 3 , Devaya Achappa 3 , Wasiq Mehmood 3 , Masaaki Oikawa 3 , Tatiana Vinardell 3 4 , Camilla Jamieson 3 5
Affiliations

1 University of Saskatchewan College of Veterinary Medicine, Saskatchewan, Canada.
2 Umm Qarn Farm, Umm Qarn, Qatar.
3 Equine Veterinary Medical Center, Education City, Qatar Foundation, Doha, Qatar.
4 College of Health and Life Sciences, Qatar Foundation, Hamad Bin Khalifa University, Doha, Qatar.
5 College of Veterinary Medicine, Purdue University, West Lafayette, Indiana.

PMID: 37221932
PMCID: PMC10357273
DOI: 10.1002/vms3.1142

Free PMC article
Abstract

Background: Upper respiratory disease was reported over many seasons in Arabian foals on a single stud farm in the Middle East. Affected foals were noted to have mucopurulent nasal discharge, cough, fever and tachypnea. All affected foals had been empirically treated with a macrolide and rifampicin, by the referring veterinarian without improvement. On endoscopic examination, all affected foals had significant guttural pouch empyema (GPE).

Objectives: (1) To document a previously unreported presentation of guttural pouch empyema (GPE) in a family of juvenile Arabian foals; (2) To document the cytological and microbial composition of the empyema; (3) To identify clinical signs significantly correlated with the presence of GPE, as predictors for the need for guttural pouch (GP) endoscopy; (4) To demonstrate successful resolution of the identified syndrome with mechanical GP lavage and evidence based antimicrobial use, improving antibiotic stewardship and the one-health approach to respiratory disease in this demographic of foals.

Methods: Evaluation and scoring of clinical signs, upper airway endoscopy and thoracic ultrasound were performed in 14 affected foals and 10 age-matched controls, followed by comparative tracheal and guttural pouch sputum culture and cytological evaluation. Therapeutic GP lavage was performed and response to therapy monitored.

Results: GPE, cranioventrally distributed ultrasonographic lesions and opportunistic pathogen infection suggested a primary lesion of GPE with aspiration of GP discharge into the lungs. GP lavage resolved the empyema and associated clinical signs in all cases.

Conclusions: Cytological examination of tracheal and guttural pouch aspirates revealed a neutrophilic exudate with lipid-laden phagocytes, suggestive of engulfed milk. Bacteriology revealed a high prevalence of Streptococcus equi ssp. zooepidemicus admixed with other opportunistic pathogens. Streptococcus equi ssp. equi was not isolated in any case.

This study characterises a previously unreported syndrome of dysphagia related GPE in young Arabian horses. Evidence suggests that show type Arabian foals presenting for upper respiratory disease with nasal discharge may be aspirating milk into the GPs and trachea and should be examined endoscopically including examination of the GPs, prior to initiation of empirical antibiotic therapy, to reduce unnecessary and ineffective antibiotic therapy.

Management of Arabian foals with GPE should include mechanical decontamination via high volume GP lavage and targeted antibiotic treatment based on bacterial culture and sensitivity testing to reduce use of high-level antibiotics like rifampicin and macrolides without thorough diagnostic evaluation.

Keywords: Arabian; antibiotic stewardship; empyema; foal; guttural pouch.

© 2023 The Authors. Veterinary Medicine and Science published by John Wiley & Sons Ltd.
Conflict of interest statement

The authors declare no conflict of interest in the undertaking or funding of this work