Received: 6 November 2023 | Accepted: 20 May 2024 DOI: 10.1111/eve.14015_1


C A S E R E POR T


Successful management of pneumonia and pyogranulomatous cranial mediastinitis due to Coccidioides species infection with fluconazole in a 3- year- old horse


Kathleen R. Mullen 1 | Melissa Fenn 1 | Jacqueline A. Hill 1 | Kate Alexander 1 | Cristy Rocio Gonzalez- Barrientos 2 | Aline Rodrigues- Hoffmann 3 | Gerald E. Duhamel 2


1 Littleton Equine Medical Center , Littleton , Colorado , USA 2 New York State Animal Health Diagnostic Center , Cornell University , Ithaca , New York , USA 3 Texas A&M Veterinary Medical Diagnostic Laboratory , College Station , Texas , USA


Correspondence: Kathleen R. Mullen Email: kathleen.mullen@cuanschutz.edu


SUMMARY


A 3- year- old Quarter Horse gelding presented for fever and inappe- tence. The horse was quiet, alert and responsive with a rectal tem- perature of 101.3°F (38.5°C), a pulse of 48 beats/min and a respiratory rate of 16 breaths/min. During rebreathing examination, the horse became agitated, coughed and had a prolonged recovery. Bloodwork was consistent with a chronic neutrophilic inflammatory process. Ultrasonography along the left and right fourth intercostal spaces re- vealed an encapsulated, mixed echogenic cranial mediastinal mass that displaced the heart caudally. Histological evaluation of needle biop- sies of the mass obtained under general anaesthesia revealed a severe pyogranulomatous inflammatory process associated with intralesional round, 15–25 μm diameter, fungal structures with a thick double- contoured cell wall (Figure 1). Panfungal PCR assay and sequencing of DNA extracted from the paraffin- embedded biopsy sample had a


99.1% identity to either Coccidioides immitis or C. posadessii . Bronchial alveolar lavage fluid cytology revealed 96% moderately degenerative neutrophils and 4% macrophages. No fungal structures were appreci- ated. However, the mediastinitis could have resulted from inhalation and dissemination of arthroconidia through lymphatics or directly from the lung parenchyma. Quantitative immunodiffusion of serum for the presence of coccidioidal IgG antibodies yielded a titre of 1:256 sugges- tive of disseminated coccidioidomycosis. After 24 months of oral flu- conazole, the horse ' s general health and athletic performance returned to normal and the mediastinal mass was no longer seen sonographically.


K E YWORDS horse , antifungal , Coccidioides , coccidioidomycosis , fluconazole


Key points


• Coccidioidomycosis was confirmed based on histological evaluation and a panfungal PCR assay of needle biop- sies taken from a cranial mediastinal mass. Coccidioidal serum IgG antibody titre of 1:256 suggested disseminated coccidioidomycosis.


• The disease resolved after long- term oral fluconazole therapy.


FIGURE 1 Photomicrograph of biopsy sample (H&E stain) showing fungal organisms (arrows) and intense granulomatous inflammation, including multinucleated giant cells (arrowhead).


• The geographic range of coccidioidomycosis may be ex- panding due to climate change.


This is an open access article under the terms of the Creative Commons Attribution-NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes. © 2024 The Author(s). Equine Veterinary Education published by John Wiley & Sons Ltd on behalf of EVJ Ltd.


564 | aaep.org/wiley-redirect Equine Vet Educ. 2024;36:564.


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52  |  Page 53  |  Page 54  |  Page 55  |  Page 56  |  Page 57  |  Page 58  |  Page 59  |  Page 60  |  Page 61  |  Page 62  |  Page 63  |  Page 64  |  Page 65  |  Page 66  |  Page 67  |  Page 68  |  Page 69  |  Page 70  |  Page 71  |  Page 72  |  Page 73  |  Page 74  |  Page 75  |  Page 76  |  Page 77  |  Page 78  |  Page 79  |  Page 80  |  Page 81  |  Page 82  |  Page 83  |  Page 84  |  Page 85  |  Page 86  |  Page 87  |  Page 88  |  Page 89  |  Page 90  |  Page 91  |  Page 92