Rare Exserohilum rhinitis case expands bovine fungal differential
Bottom line
A newly published case report in the Journal of Veterinary Diagnostic Investigation describes granulomatous rhinitis caused by Exserohilum rostratum in an adult Holstein cow from a dairy herd in Uruguay, adding a rare bovine presentation to the literature on this dematiaceous fungus. The cow developed bilateral nasal mucosal nodules in March 2024, with dyspnea, snoring, nasal discharge, and weight loss. The paper also reviews older ruminant reports tied to Exserohilum and historically related names such as Helminthosporium, Drechslera, and Bipolaris, underscoring how taxonomy changes can obscure case recognition across the veterinary literature. (lifescience.net)
Why it matters: For veterinary professionals, the report is a reminder that chronic nodular or granulomatous nasal disease in cattle isn't always allergic rhinitis or a more familiar fungal process. Published bovine and small-ruminant reports suggest Exserohilum infections can involve the skin and nasal cavity, and older cases may be buried under outdated organism names. That makes histopathology, fungal culture, and molecular identification especially important when upper-airway lesions don't fit the usual pattern. (lifescience.net)
What to watch: Watch for whether this case prompts more retrospective reclassification of older “Drechslera” or “Bipolaris” ruminant cases, and whether additional bovine nasal infections are identified now that the paper was published on September 22, 2026. (lifescience.net)
Key facts
- Journal
- Journal of Veterinary Diagnostic Investigation
- Species
- Adult Holstein cow
- Location
- Uruguay
- Condition
- Granulomatous rhinitis
- Cause
- Exserohilum rostratum
- Clinical signs
- Bilateral nasal mucosal nodules, dyspnea, snoring, nasal discharge, and weight loss
- Case date
- March 2024
- Publication date
- September 22, 2026
- Literature review focus
- Domestic ruminant diseases caused by Exserohilum spp. and historical synonyms, including Helminthosporium, Drechslera, and Bipolaris
A new Journal of Veterinary Diagnostic Investigation report details Exserohilum rostratum granulomatous rhinitis in a Holstein cow, highlighting an uncommon fungal differential for chronic upper-airway disease in cattle. The case involved an adult dairy cow in Uruguay that developed bilateral nasal nodules and progressive respiratory signs in March 2024; the article was published online on September 22, 2026. (lifescience.net)
What makes the paper especially useful is that it doesn't stop at a single case. The authors pair the case report with a literature review covering disease caused in domestic ruminants by Exserohilum species and by fungi historically labeled Helminthosporium, Drechslera, or Bipolaris. That matters because fungal nomenclature has shifted substantially over time, and modern phylogenetic work has shown that several previously named Exserohilum species are conspecific with E. rostratum. In practice, that means older reports may be easy to miss unless clinicians and diagnosticians search across synonym-heavy terminology. (lifescience.net)
According to the abstracted report, the cow presented with bilateral nodules in the nasal mucosa along with dyspnea, snoring, nasal discharge, and weight loss. Histologically, the lesion was described as a severe chronic eosinophilic granulomatous process, fitting the broader pattern seen in some fungal rhinitis cases in cattle. Older bovine literature has documented related disease patterns, including dermal granulomas and cases in which nasal involvement followed cutaneous disease, while a 2023 goat report also described rhinitis caused by E. rostratum. (lifescience.net)
The broader literature suggests this remains a rare diagnosis, not a routine cause of bovine nasal disease. Merck Veterinary Manual notes that enzootic nasal granuloma and allergic rhinitis are more established considerations in cattle with chronic nasal granulomatous lesions, while other case reports show that unusual fungi such as Pseudallescheria boydii can produce a similar eosinophilic, granulomatous rhinitis picture. For diagnosticians, that's the core challenge: morphology may point to fungal disease, but species-level identification often requires culture and, increasingly, PCR or sequencing. (merckvetmanual.com)
I didn't find a dedicated institutional press release or published expert commentary specific to this September 2026 paper. Still, related peer-reviewed reports help frame the significance. A 2024 bovine dermatology case report noted that cattle infections attributed to Exserohilum are uncommon and that older bovine mycotic granuloma cases were sometimes reported without species identification or under the name Drechslera rostrata, now considered E. rostratum. That supports the new paper's emphasis on historical synonyms and under-recognition. (pmc.ncbi.nlm.nih.gov)
Why it matters: For veterinary professionals, this is less about a likely surge in cases and more about sharpening the differential list. In cattle with chronic nodular rhinitis, stertor, discharge, and weight loss, especially when lesions are eosinophilic and granulomatous on biopsy, uncommon dematiaceous fungi deserve consideration alongside allergic and more familiar infectious causes. The report also reinforces the value of preserving samples for mycology and molecular work, because accurate naming affects literature retrieval, case comparison, and any future understanding of epidemiology in dairy herds. (lifescience.net)
There may also be a One Health angle, even if this paper is strictly a veterinary diagnostic report. E. rostratum is best known outside veterinary medicine for rare but sometimes severe opportunistic infections in people, and the organism has been described as a cross-kingdom pathogen affecting plants and humans. That doesn't make this bovine case a public health event, but it does reinforce that environmental fungi with broad host range can show up in unexpected clinical settings. (pmc.ncbi.nlm.nih.gov)
What to watch: The next step is whether this publication leads pathologists and veterinary diagnosticians to revisit archived bovine nasal granuloma and dermatomycosis cases under older names, and whether additional reports clarify risk factors, geographic distribution, and the best diagnostic workflow for suspected Exserohilum infection in ruminants. (lifescience.net)