Osteopathology and selenium deficiency co-occurring in a population of endangered Patagonian huemul (Hippocamelus bisulcus)

Abstract

BackgroundAbout 1,000 endangered Patagonian huemul deer (Hippocamelus bisulcus) remain in Chile and 350–500 in Argentina. Most groups (>100) are not recovering, and prevalence of osteopathology in Argentina was at least 57%. Here I describe relevant cases of osteopathology from a Chilean population which, however, recently also provided data on trace mineral status, supporting the initial hypothesis that nutrition may be a primary etiologic factor. Additionally, recent data on bone chemical composition of Argentine cases and soil analyses are discussed.ResultsFluoride levels in Argentine cases with osteopathology were low and fluorosis was discarded as an etiological factor. Selenium deficiency occurred in 73% of huemul from the Chilean population which exhibited several cases with osteopathology. The pathophysiognomy included extensive erosion; tooth loss; porosification; perforations of palate, maxillar and mandibular bone with frequent exposure of tooth roots; and fractured mandibula. Areas currently used by remaining huemul have mainly acidic volcanic soils, which reduces selenium bioavailability: mean soil selenium levels from areas typically used by extant huemul were very deficient (0.19 ppm), corroborating documented overt selenium deficiency in local livestock and plants. The area of extant huemul is known to result in primary iodine deficiency in livestock which is aggravated by selenium deficiency.ConclusionsCurrently the most parsimonious explanation for frequent osteopathology and lack of numerical recovery are the combined effects of selenium and iodine deficiencies based on: osteopathology in a population of selenium deficient huemul; selenium deficient livestock, plants and soils; acidic soils; and regional primary iodine deficiency. The nexus between mineral nutrition and population dynamics of huemul may be due to constraints on their movements to fertile lowlands, including the elimination of historic migratory traditions, and concomitant elimination of source populations.

Troubling disease syndrome in endangered live Patagonian huemul deer (Hippocamelus bisulcus) from the Protected Park Shoonem: unusually high prevalence of osteopathology

“…Selenium (Se) deficiency, which impairs bone metabolism and causes periodontitis in ruminants, occurs regionally and is more prevalent at high altitudes where extant huemul tend to remain. This was recently corroborated in Chilean huemul, which were also afflicted with such osteopathology, and severe Se deficiency [ 5 , 6 ]. The presented novel data about types and prevalence of osteopathology in live huemul extends previously documented postmortem cases [ 2 , 6 ] and furthermore lends imperative support for the hitherto hypothesized causal relationship between nutritional constraints as factors which have prevented the recovery of most of the > 100 fragmented subpopulations.…”

“…The high prevalence of osteopathology in carcasses is now also substantiated for live huemul. The clinical severity of osteopathology in carcasses from Argentina (this study, 2) and Chile [ 6 ] demonstrate the severity of the disease status of these recently radio-collared huemul.…”

“…In case of accompanying infections, it is fundamental to determine if they are of primary versus secondary origin. Fluorosis was discarded for Argentine huemul [ 6 , 12 ]. However, iodine deficiency in southern Chile is documented in people [ 13 ] and livestock [ 14 , 15 ].…”

Elusive cranial lesions severely afflicting young endangered Patagonian huemul deer

“…Deficiency of Se in cervids and other ruminants impairs bone metabolism and causes periodontitis [23]: it occurs in huemul areas and is more prevalent where extant huemul tend to remain, namely at high altitudes. Such severe Se deficiency was corroborated in a Chilean huemul population, which simultaneously was also affected with this osteopathology [16, 20]. For southern Chile, the most common trace mineral imbalance recognized in dairy herds is Se deficiency [21].…”

Dental Defects as a Potential Indicator of Chronic Malnutrition in a Population of Fallow Deer (Dama dama) from Northwestern Germany

“…It has been assumed (Flueck, ) that in habitats characterized by acidic soils, as is the case in our study area, selenium deficiency can cause bone lesions in the resident deer population. We, therefore, wish to emphasize that we did not observe any pathological alterations of the mandibular bone in the studied fallow deer that would be suggestive of a selenium deficiency.…”