New hair-shaft lesions described in northern elephant seals
Bottom line
Northern elephant seals with dermatologic disease may have two previously undescribed hair lesions, according to a new histologic and ultrastructural study in Veterinary Dermatology. The authors report crescentic hair shaft defects, or CHSD, and fungal piedra-like lesions, or PLL, in northern elephant seals (Mirounga angustirostris), finding the lesions in 61% of animals with dermatologic disease and linking them with bacterial and fungal colonization, follicular invasion, and hair fragility. The work adds a new morphologic layer to an old clinical problem in this species: northern elephant seal skin disease, now also described as northern elephant seal dermatopathy, a potentially fatal ulcerative skin condition that has been recognized for decades in stranded juveniles and yearlings. (researchgate.net)
Why it matters: For veterinary professionals working in marine mammal medicine, pathology, or rehabilitation, the findings may help sharpen differential diagnoses in alopecic or ulcerative skin cases that have historically had an uncertain cause. Prior work from The Marine Mammal Center described northern elephant seal skin disease as a syndrome of alopecia, hyperpigmentation, ulceration, and sometimes necrosis in mostly young animals, with systemic illness and increased septicemia risk in severe cases. The new study, together with earlier Cornell-supported mycobiome work suggesting that keratinophilic bacteria or fungi may contribute to hair fragility and breakage, points to hair shaft and follicular pathology as a potentially important part of the disease process rather than a superficial secondary finding alone. (researchgate.net)
What to watch: Watch for follow-up studies on organism identification, prevalence in healthy versus stranded seals, and whether CHSD and PLL become useful diagnostic markers or therapeutic targets in northern elephant seal dermatopathy. (vet.cornell.edu)
Key facts
- Species
- Northern elephant seals (*Mirounga angustirostris*)
- Study type
- Histologic and ultrastructural study
- Journal
- *Veterinary Dermatology*
- Lesions described
- Crescentic hair shaft defects (CHSD) and piedra-like lesions (PLL)
- Finding frequency
- Found in 61% of animals with dermatologic disease
- Associated findings
- Bacterial and fungal colonization, follicular invasion, and hair fragility
- Clinical context
- Northern elephant seal skin disease, also called northern elephant seal dermatopathy, is a potentially fatal ulcerative skin condition
- Affected animals
- Recognized for decades in stranded juveniles and yearlings
A new Veterinary Dermatology study describes two apparently novel hair lesions in northern elephant seals that could help explain part of a long-running dermatology puzzle in the species. The lesions, termed crescentic hair shaft defects and piedra-like lesions with follicular invasion, were identified on histologic and ultrastructural examination and were found in 61% of animals with dermatologic disease, with evidence of associated bacterial and fungal colonization. (vet.cornell.edu)
That matters because skin disease in northern elephant seals is not new, but its pathogenesis has remained unsettled. A landmark 1997 report from The Marine Mammal Center characterized northern elephant seal skin disease, or NESSD, as a generalized ulcerative dermatitis seen mainly in immature animals, with patchy to extensive alopecia, hyperpigmentation, epidermal ulceration, and occasional massive skin necrosis. In that series, affected seals were typically under 2 years old, often emaciated, depressed, and dehydrated, and mortality from septicemia increased with worsening ulceration. (researchgate.net)
More recently, investigators have referred to the syndrome as northern elephant seal dermatopathy, or NESD. A 2022 case abstract describing a stranded yearling male from 2021 called it the first reported case in two decades and noted severe, widespread skin lesions, along with histologic findings including vasculitis, thrombosis, coagulative necrosis, sebaceous adenitis, and sebaceous gland metaplasia. That report underscores that clinically important dermatologic disease is still on the radar in stranded elephant seals, even if published case descriptions have been sparse. (researchgate.net)
The new hair-shaft study also fits with earlier research efforts aimed at the skin microbiome and mycobiome of healthy and alopecic northern elephant seals. A Cornell College of Veterinary Medicine project led by Vivian Lee, with Jeanine Peters-Kennedy as co-mentor, stated that preliminary histopathology and electron microscopy had already suggested hair shaft organisms might be associated with alopecia in this species. The project specifically hypothesized that a keratinophilic bacterium or fungus could contribute to hair fragility and breakage, which now looks prescient in light of the reported CHSD and piedra-like lesions. (vet.cornell.edu)
Direct outside commentary on this specific paper appears limited so far, but the broader dermatology context is familiar to marine mammal clinicians and pathologists. Standard descriptions of piedra in other species characterize it as a fungal infection producing nodules on hair shafts, so the “piedra-like” terminology signals that the authors are placing these lesions within a recognizable hair-disorder framework while stopping short of overclaiming a classic diagnosis without fuller organism characterization. That’s an inference from the terminology and background literature, not a direct statement from the study authors. (pmc.ncbi.nlm.nih.gov)
Why it matters: For veterinary professionals, the practical value is in pattern recognition and case workup. In stranded juvenile or yearling elephant seals with alopecia, crusting, ulceration, or abnormal molt, these lesions may offer a more precise histopathologic explanation for hair loss and secondary skin compromise. They also strengthen the case for pairing routine histopathology with targeted microbial assessment, including fungal evaluation, when marine mammal dermatology cases are investigated. If follicular invasion and shaft fragility are reproducible findings, they could eventually help distinguish primary hair pathology from secondary colonization in a syndrome that has long been clinically important but mechanistically murky. (researchgate.net)
The findings may also have implications beyond individual case management. Northern elephant seals are protected marine mammals, and dermatologic syndromes in stranded animals can reflect larger questions about nutrition, molt physiology, environmental stress, microbiology, and contaminant exposure. Earlier work on NESSD found associations with endocrine and nutritional abnormalities, while stopping short of a definitive cause. The new lesion descriptions don’t settle that debate, but they do add concrete morphologic evidence that may help future studies connect clinical disease with microbial ecology and host factors. (researchgate.net)
What to watch: The next step is likely organism-level follow-up: culture-independent mycobiome and microbiome data, clearer prevalence estimates in healthy versus diseased animals, and work to determine whether CHSD and piedra-like lesions are drivers of disease, opportunistic sequelae, or both. For clinicians and pathologists, this is the kind of descriptive paper that can quietly change how cases are sampled, read, and discussed long before it changes treatment protocols. (vet.cornell.edu)