EQUINE VETERINARY EDUCATION / AE / AUGUST 2020


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Fig 6: Endometrial biopsy stained with PAS showing Candida spp. spores within the uterine lumen over uterine epithelium.


2017). Unfortunately, there is a lack of controlled studies in the literature regarding appropriate dose and duration of therapy required to treat fungal endometritis in the mare (Table 2). In an aim to improve treatment efficacy, Beltaire et al.


(2012) cultured 102 fungal isolates, from 92 uterine samples taken from mares with reproductive problems and determined in vitro susceptibility to commonly used antifungals. Yeast isolates were 100% sensitive to polyenes, but susceptibility to azoles varied considerably: ketoconazole (90%), fluconazole (61%) and miconazole (48%). About 69–100% of moulds with septated hyphae were susceptible to polyenes, but the susceptibility to azoles was significantly lower compared with the yeast isolates, with 54% of moulds showing resistance or intermediate susceptibility to itraconazole and 100% showing resistance to fluconazole. Hess et al. (2002) successfully treated four mares


Fig 5: a) Aspergillus spp. cultured on Sabouraud's dextrose agar. b) Endometrial cytology of Aspergillus spp. and inflammatory cell debris stained with Trichome stain.


Ideally specific antifungal sensitivity patterns should be


determined prior to treatment, but due to limited availability and prolonged testing times, many cases are treated empirically whilst awaiting culture results. The two major classes of antifungals used are azoles and polyenes; their mechanism of action is to interfere with the cytoplasmic membrane of fungi. Polyenes bind to ergosterol and destabilise the membrane whereas azoles inhibit ergosterol biosynthesis. Polyenes are thought to be fungicidal and azoles fungistatic which may in part account for the increased resistance seen to azoles (Campoy and Adrio


diagnosed with fungal endometritis caused by either Candida spp. or Aspergillus spp. with a single intrauterine administration of 540 mg Lufenuron (Program2). Lufenuron is thought to inhibit fungal growth by interfering with chitin biosynthesis. However, since not all fungal organisms have chitin in their cell walls, Lufenuron may not be effective in all cases. Scotty et al. (2005) failed to demonstrate in vitro antifungal activity against Aspergillus spp. and Hector et al. (2005) tested in vitro antifungal properties of lufenuron against isolates of Coccidioides immitis and Aspergillus fumigatus and found no evidence of inhibition, under experimental conditions. Weinstein et al. (2006) found the third-generation buffered


chelator TricideTM,3 to potentiate the antimicrobial effects in vitro of antifungal agents against isolates obtained from clinical cases of equine fungal keratitis. Whilst the use of chelating agents in fungal endometritis has not been studied to date, there is in vitro evidence to support their use in bacterial endometritis (Ferris et al. 2016). Oral administration of fluconazole (15 mg/kg bwt per os


loading dose followed by 5 mg/kg bwt per os q. 24 h) has been shown to achieve endometrial concentrations near or above MIC for Candida albicans (Scofield et al. 2011) and is well tolerated in the horse (Table 3). Systemic treatment is recommended based on sensitivity patterns and may help with invasive forms that are not exposed to luminal therapies and reduce the risk of iatrogenic infection associated with


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