Hypoaminoacidemia is not Associated with Ulcerative Lesions in Black Rhinoceroses, Diceros bicornis

Abstract

Ulcerative oral and skin lesions have become an issue of concern for the health of the managed black rhinoceros (rhino) (Diceros bicornis) populations. Lesions exhibited by the black rhino are clinically similar to those observed in other species with superficial necrolytic dermatitis (SND). One biochemical alteration in dogs with SND is severe hypoaminoacidemia, and nearly all cases are fatal. The objective of this study was to determine if black rhinos with analogous lesions exhibit a similar hypoaminoacidemia. Amino acid concentrations were measured in monthly plasma samples collected for 1 yr from black rhinos with (n = 4) and without (n = 34) lesions clinically consistent with SND. The rhinos with skin and/or oral lesions were zoo born males, ages 2, 6, 17, and 23 yr, from four different facilities. Three rhinos recovered from skin (n = 2) and oral lesions (n = 1). However, the one male with both skin and oral lesions died with the disease. None of the affected black rhinos exhibited a decrease in any of the amino acids evaluated or for total amino acid concentrations (P > 0.05). Based on the absence of hypoaminoacidemia and the comparatively low mortality rate in rhinos with lesions, it appears that this syndrome is not entirely consistent with SND observed in other species. These data will be useful for future assessments of rhino nutritional status and other potential metabolic diseases.

Decreased Baseline Fecal Glucocorticoid Concentrations Associated with Skin and Oral Lesions in Black Rhinoceros (Diceros bicornis)

“…5,8 Therefore, adrenal hyperplasia may indicate chronic stress. 7 Adrenal hyperplasia has been documented through postmortem examinations in several species. 14,21-23 Several cases of adrenal hyperplasia have been observed in black rhinos in zoos.…”

“…First, one of the major symptoms of SND in dogs, hypoaminoacidemia, was not observed in affected black rhinos. 7 Second, the mortality rate in dogs is almost 100%, whereas rhinos with lesions frequently recover from episodes without treatment, although recurrence is common. 6,16,18 Third, SND lesions affect primarily older dogs, whereas skin and oral lesions in black rhinos occur in animals of all ages.…”

Topical treatment of multiple erosive, ulcerative skin lesions in an Indian rhinoceros (Rhinoceros unicornis)

“…In the Indian rhinoceros a too high amount of crude fibre can lead to laminitis [1], hypovitaminosis E in the black rhinoceros is suspected to cause haemolytic anaemia [15] and infertility in the white rhinoceros may be influenced by dietary phytoestrogens and a change in gut microbiota [16]. However, hypoaminoacidaemia was not present in black rhinoceroses with ulcerative skin lesions [17]. The environment and life style were already optimized as good as possible prior to treatment and thus fecal or urine samples were not obtained from this patient for cortisol measurement.…”

The interspecific relationships of black rhinoceros (Diceros bicornis) in Hluhluwe-iMfolozi Park

“…that may be associated with stress since captive rhino experience weight loss, pregnancy and oestrus bleeding and a two-fold increase in mortality (Dorsey 2008;Dorsey et al 2010). In other animals such as domestic cattle (Bos taurus) low body condition scores are also correlated with inceased treatment for haemorrhaging lesions of the sole (i.e., lameness) up to two to four months later .…”