Fatty acid status in captive and free-ranging black rhinoceroses (Diceros bicornis)

The fatty acid (FA) patterns of plasma/serum triglycerides (TG), phospholipids (PL) and cholesteryl esters (CE) of captive and free-ranging black rhinoceroses (Diceros bicornis) were investigated. Free-ranging animals (n = 28) stemmed from four different regions. Captive animals sampled included specimens from North American (n = 11) and three different European facilities (n = 6). The European animals were tested on 1-4 different diets, resulting in a total of 15 blood samples. Regardless of differences between the free-ranging animals from different regions, differences between captive and free-ranging animals were relatively uniform: captive animals had higher overall proportions of polyunsaturated fatty acid (PUFA), due to levels of linoleic acid (LA, 18:2n6) that were drastically increased as compared to free-ranging animals. In contrast, levels of alpha-linolenic acid (ALA, 18:3n3) were consistently lower on conventional zoo diets. n6/n3 ratios for TG, PL and CE were 1.6, 10 and 8 in samples from free-ranging animals, respectively, as compared to 4.1-16.3, 16-148 and 40-277 in samples from captive animals. There was a distinct correlation between the proportion of grain-based products (commercial concentrates, plain grains and bread) in the diets of the European animals and the measured levels of n6 PUFA. An animal from a facility with a very low proportion of grain products in the diet nevertheless had high LA readings, most probably due to the use of sunflower oil as 2% (dry matter basis) of its diet. One animal that received a high proportion of grass meal pellets due to an oral disease had increased ALA contents after the diet change. These results allow conclusions on the suitability of diets fed in captivity: the black rhinoceros is prone to several uncommon diseases that have been suspected to be linked to oxidative damage, possibly due to the disposition of this species to excessive iron storage. An unnatural dietary loading with PUFAs would exacerbate this problem. Additionally, n6 FAs are known as precursors of pro-inflammatory mediators, and their overrepresentation could therefore exacerbate any inflammatory processes. Therefore, the current practice of using grain-based feeds as major ingredients in captive rhinoceros diets is discouraged. Diet items containing ALA (a precursor of anti-inflammatory mediators) such as, fresh grass, fresh browse, the respective silages should be included at higher levels in diets for captive black rhinoceroses. Grass meal pellets, although a good source of ALA and linked with high levels of ALA in an animal of this study, must be chosen with care for black rhinoceroses due to their particular proneness for high iron contents.     

Leptospira infection in two black rhinoceroses (Diceros bicornis michaeli).

Two black rhinoceroses (Diceros bicornis michaeli) developed clinical leptospirosis without hemolytic crises. The first rhinoceros presented with peracute depression, anorexia, rear leg trembling, dysuria, glucosuria, gastrointestinal discomfort, and decreased fecal output and died within 12 hr. Necropsy and histopathology revealed lesions within multiple organs. Leptospirosis was diagnosed postmortem based on positive fluorescent antibody staining of liver. The second rhinoceros presented 2 mo later with similar signs. It survived with treatment and was diagnosed with leptospirosis based on serology using microscopic agglutination testing and detection of urinary antigen using a fluorescent antibody technique. Leptospira kirschneri serovar grippotyphosa was postulated as the etiologic agent, with transmission probably occurring through wallow contamination by wild raccoons (Procyon lotor).     

Reproductive parameters in free-ranging female black rhinoceroses (Diceros bicornis) in Zimbabwe

Samples and data were collected from twenty-eight female black rhinoceroses (Diceros bicornis) during translocation efforts carried out by the Department of National Parks and Wildlife Management in Zimbabwe. Biological data were collected, cytological examination of vaginal smears was performed, and serum concentrations of follicle stimulating hormone, luteinizing hormone, progesterone, oestriol, and 17-beta-oestradiol were determined by radio-immuno-assay. Prolactin levels were determined for 3 pregnant animals, 1 of which was sampled before and after parturition. Vaginal cytology was not found to be helpful for indicating the oestrous cycle stage for the black rhinoceros, but progesterone and 17-beta-oestradiol levels were found to be useful indicators of pregnancy and possibly of oestrous cycle stage as well.     

A review of some of the health issues of captive black rhinoceroses (Diceros bicornis).

In captivity, black rhinoceroses (Diceros bicornis) are beset by many disease syndromes not described in black rhinoceroses in the wild. Hemolytic anemia, hepatopathy, and ulcerative dermatopathy that lead to increased morbidity and mortality characterize these syndromes. It is uncertain whether these are separate disease syndromes with different etiologies or the same disease with different manifestations. This article offers a brief review of some of the health issues of concern for the captive black rhinoceros population and proposes some possible avenues of research for consideration.     

Role of excessive maternal iron in the pathogenesis of congenital leukoencephalomalacia in captive black rhinoceroses (Diceros bicornis)

OBJECTIVE: To investigate the possibility that excessive maternal iron (overload) may contribute to development of congenital leukoencephalomalacia in captive black rhinoceroses. SAMPLE POPULATION: Tissue specimens and serum samples from 18 rhinoceroses in 2 kindreds harboring 4 (possibly 5) affected female calves. PROCEDURE: Fresh and archival sera and necropsy tissue specimens were evaluated to determine the nature and extent of iron overload in captive and wild black rhinoceroses as well as other rhinoceros species. RESULTS: Quantitative serum and tissue assays of iron and iron analytes, corroborated by histopathologic findings, indicated that these kindreds carried the greatest body burdens of iron yet found among captive black rhinoceroses. Fourteen of 18 rhinoceroses had the highest serum ferritin concentrations measured among 64 black rhinoceroses in captivity in the United States. Dams of affected calves had serum ferritin concentrations 2 orders of magnitude higher than clinically normal humans, equids, or free-ranging rhinoceroses. A neonatal serum sample from 1 affected female calf had a high ferritin concentration (approx 100-fold increase), but a male sibling of another affected female did not, suggesting a possible sex disparity in fetal response to maternal iron overload. Morphologic hallmarks of hemochromatosis were prominent in dams and grandams of affected calves. CONCLUSIONS AND CLINICAL RELEVANCE: Excessive maternal iron may affect female fetuses more than males, possibly inducing leukoencephalomalacia by catalyzing production of highly toxic hydroxyl free radicals during crucial periods of in utero development. Reduction of maternal iron overload may decrease the probability of developing leukoencephalomalacia and some other disorders commonly affecting rhinoceroses in captivity.     

High serum concentrations of iron, transferrin saturation and gamma glutamyl transferase in captive black rhinoceroses (Diceros bicornis)

Iron storage disease (haemochromatosis) is thought to be the cause of many disorders unique to captive black rhinoceroses (Diceros bicornis). To establish reliable reference ranges for iron parameters, serum samples from 27 eastern black rhinoceroses (Diceros bicornis michaeli) from a translocation programme in Kenya were analysed and compared with the samples from 17 captive individuals. The transferrin saturation, serum iron concentration and gamma glutamyl transferase were significantly higher in the captive rhinoceroses, but these elevations were not evident when the results were compared with previously published data.     

Risk factors associated with a skewed natal sex ratio in captive black rhinoceroses (Diceros bicornis) in the United States.

The skew toward males in the sex ratio of calves is considered to be a problem for the captive population of black rhinoceroses (Diceros bicornis) in North America. This study used a retrospective case-control design to determine whether there was a predisposition toward birth of male calves over female calves and to examine risk factors associated with the occurrence of any detected skewed natal sex ratio in captive black rhinoceroses in the United States. The study population included captive female black rhinoceroses housed in the United States that had given birth to at least one calf of known sex. This study confirmed a skewing of the natal sex ratio toward male calves in the captive black rhinoceros population. The skewed ratio was found in calves born to wild-born dams, for which an increased time in captivity, irrespective of age, was associated with an increased likelihood of a male calf. Dams between 12 and 19 yr of age had a decreased likelihood of a male calf. The data also suggested a possible trend for the southern subspecies of black rhinoceros (Diceros bicornis minor) to be more likely to produce male calves than the eastern subspecies (Diceros bicornis michaeli). No associations were found with the sex of offspring in captive-born dams: however, this lack of association could be a result of low power in the study.     

Overdose during chemical restraint in a black rhinoceros (Diceros bicornis)

A juvenile female black rhinoceros (Diceros bicornis) was successfully treated after overdose of drugs used for chemical restraint. Subsequent general anaesthesia for surgical reduction of a recurrent rectal prolapse was uneventful. Over a 25-minute period before transportation to the veterinary hospital, the animal received a total dose of 1.225 mg etorphine, 30 mg acepromazine and 30 mg detomidine. Based on an estimated mass of 200 kg, these corresponded to doses of 6.1 microg kg(-1) etorphine, 150 microg kg(-1) acepromazine, and 150 microg kg(-1) detomidine which constitutes considerable overdose for each drug given separately, notwithstanding the synergy that probably resulted when the three drugs were present concurrently. The estimated body mass may have substantially overestimated the actual body mass and exacerbated overdosage. The animal was recumbent and apnoeic on arrival at the hospital. Heart sounds were auscultated and a weak peripheral pulse was palpated; no pulse deficits were detected, although the heart rate was low. The trachea was intubated, inspired breath was enriched with oxygen and the lungs ventilated manually. Diprenorphine (1.5 mg) was given intravenously and spontaneous breathing resumed 11 minutes later. After induction of general anaesthesia using isoflurane, emergency surgery for correction of rectal prolapse was performed, from which the animal recovered uneventfully. The case highlights some of the practical problems that may be encountered in dealing with dangerous and unfamiliar species.     

Morphology of the dorsal lingual papillae in the black rhinoceros (Diceros bicornis)

The dorsal lingual surface of a black rhinoceros (Diceros bicornis) was examined by scanning electron microscopy. The tongue was about 30 cm in length. There were about 60 vallate papillae on both sides. Filiform, fungiform and vallate papillae were found. The filiform papillae were distributed over the entire dorsal surface of the tongue. The papillae had a hair-like shape. The fungiform papillae were round in shape, and more densely distributed on the lingual apex. No foliate papillae were seen on the dorsal surface. The vallate papillae were located on both sides of the posterior end of the lingual body. Each papilla was surrounded by a groove.     

Globular periodontal cement dysplasia in a black rhinoceros (Diceros bicornis)]

A globular periodontal cementous dysplasia in a 18 years old black rhinoceros (Diceros bicornis) is diagnosed by gross pathology, X-ray, and by histological examinations. The findings are discussed.     

The importation of the black rhinoceros (Diceros bicornis) from Zimbabwe into Australia

SUMMARY The paper describes a program to import and breed black rhinoceros ex situ at Western Plains Zoo in Australia. Nine rhinoceros (7 females and 2 males) captured in 1992 in Chete National Park, Zimbabwe, were transported to Australia via Cocos Island. The veterinary treatment of the animals before and during quarantine in Zimbabwe and on Cocos (Keeling) Islands is described. Three animals died; an adult male on Cocos Islands and a juvenile male and an adult female at Western Plains Zoo, Dubbo, New South Wales. The juvenile male died as a result of trauma sustained shortly after arrival and the two adults after developing a severe hepatopathy. The group of 6 females and an additional 4 males imported from the USA in 1994 have adapted well to captivity and to the climate and environment of central west New South Wales.     

Mineral absorption in the black rhinoceros (Diceros bicornis) as compared with the domestic horse

To test whether mineral recommendations for horses are likely to guarantee adequate mineral provision for black rhinoceroses (Diceros bicornis), we investigated the apparent absorption (aA) of macro- and microminerals in eight black rhinoceroses from three zoological institutions in a total of 32 feeding trials with total faecal collection, with additional data from three unpublished studies (18 feeding trials). Feeds and faeces were analysed for Ca, P, Mg, Na, K, Fe, Mn, Cu, Zn and Co. The resulting aA coefficients, and the linear relationships of apparently absorbable dietary mineral content to total dietary mineral content [per 100 g dry matter (DM)], were compared with data for domestic horses. Rhinoceroses had significantly higher aA coefficients for Ca and Mg (because of a higher calculated 'true' absorption), and lower ones for Na and K (because of calculated higher endogenous faecal losses). High absorption efficiency for divalent cations is hypothesized to be an adaptation to a natural diet of particularly high Ca:P ratio (approximately 14:1); an effective removal of Ca from the ingesta guarantees sufficient P availability at the fermentation site in the hindgut. Higher faecal losses of Na and K are hypothesized to be linked to a higher faecal bulk per DM intake in black rhinoceroses as compared with horses because of a generally lower digestive efficiency. There were no relevant differences in the absorption patterns of microminerals. In particular, there were no discernable differences in Fe absorption within the rhinoceroses for diets with and without tannin supplementation. Several of the zoo diets assessed in this study were deficient in Cu, Mn or Zn, and most contained excessive levels of Fe when compared with horse requirements. The findings of this study indicate that differences in mineral absorption between occur even between species of similar digestive anatomy; that in particular, Ca absorption might vary between hindgut fermenters with Ca:P ratio in their natural diet; that Na might be a particularly limiting factor in the ecology of free-ranging rhinoceroses; that moderate doses of tannins do not seem to markedly influence mineral absorption; and that diets for captive animals should contain adequate, but not excessive mineral levels.     

Idiopathic distal esophageal dilation in a southern black rhinoceros (Diceros bicornis minor).

An adult female southern black rhinoceros (Diceros bicornis minor) experienced intermittent periods of regurgitation while eating, suggesting an esophageal disorder. Endoscopy for evaluation of the trachea, esophagus, and stomach revealed a 30-mm nasopharyngeal orifice with associated recess located in the caudodorsal pharynx and a 10-cm dilated segment of the distal esophagus that was presumably the cause of regurgitation. Dietary management of esophageal dilation through short-term utilization of a "soft feed" program successfully eliminated the regurgitation. This is the first report of esophageal dysfunction in a rhinoceros.     

Acute lymphoblastic leukemia in a juvenile southern black rhinoceros (Diceros bicornis minor).

A 21-mo-old female southern black rhinoceros (Diceros bicornis minor) developed acute upper respiratory dyspnea in association with lymphadenopathy and marked immature lymphocytosis. A diagnosis of acute lymphoblastic leukemia was reached on the basis of the morphologic and cytochemical characteristics of peripheral lymphoblasts. Antineoplastic chemotherapy included administration of cytarabine, cyclophosphamide, vincristine, and doxorubicin, with clinical remission achieved 19 days after initiation of treatment. The rhinoceros died, however, of congestive heart failure, presumably secondary to doxorubicin cardiotoxicity and a particular sensitivity of rhinoceros myocardial tissue to free hydroxyl radicals. The pharmacologic effects of any therapeutic agent need to be carefully considered before use in the black rhinoceros, especially within the context of the unique physiology of this species.     

Semen collection in rhinoceroses (Rhinoceros unicornis, Diceros bicornis, Ceratotherium simum) by electroejaculation with a uniquely designed probe.

Electroejaculation in rhinoceroses has historically yielded inconsistent results, with the collection of high-quality, sperm-rich samples rare. The goal of this study was to develop a reliable method of electroejaculation in the rhinoceros by designing a rectal probe that appropriately fits the anatomy of this taxon and refining the procedure. A curved probe handle ending in an oblate, ellipsoid head was built using readily available supplies. A combination of rectal massage, penile massage, and electrical stimulation with a specially designed probe was employed in attempts to collect semen on 14 occasions from greater one-horned rhinoceroses (Rhinoceros unicornis; n = 4), black rhinoceroses (Diceros bicornis; n = 2) and a southern white rhinoceros (Ceratotherium simum; n = 1). During 13 of the 14 attempts, ejaculates were collected in multiple fractions. All but one of the ejaculates contained spermatozoa, and seven ejaculates contained good-quality fractions of semen (-60% sperm motility; > or =20 x 106 spermatozoa/ml) suitable for sperm banking and assisted reproduction procedures. Mean (+/-SEM) values for volume, pH, osmolality, and total sperm number for ejaculates containing good-quality fractions (98.2 +/-21.8 ml, 8.5+/-0.1, 290.4+/-6.7 mOsm, and 37.1+/-12.0 x 10(9), respectively) did not differ (P > 0.05) from those containing only poor-quality samples. Urine and/or erythrocyte contamination was not uncommon in fractions of both ejaculate types. Males producing good-quality samples ranged in age from 7 to 34 yr. None of the samples contained > or =75% morphologically normal spermatozoa. Electroejaculation with a uniquely designed probe consistently produced ejaculates in the rhinoceros. However, the production of high-quality samples continued to be challenging, occurring in only 50% of collection attempts. Regardless, the technology has progressed to a stage at which good-quality semen samples can be produced for sperm banking and assisted reproduction, and thereby can be integrated into intensive rhinoceros management strategies for the ultimate survival of this taxon.     

The influence of dietary tannin supplementation on digestive performance in captive black rhinoceros (Diceros bicornis)

Free-ranging browsers such as the black rhinoceros (Diceros bicornis) consume a diet that contains tannins, whereas the diets offered to them in captivity consist mostly of items known to contain hardly any such secondary plant compounds. Tannins could have potentially beneficial effects, including the chelation of dietary iron (iron storage disease is a common problem in black rhinos). Here, we tested the acceptance, and the consequences on digestion variables, of a low-dose tannin supplementation in captive animals. Eight black rhinoceroses from three zoological institutions were used. Faecal output was quantified by total faecal collection. Diets fed were regular zoo diets supplemented with either tannic acid (T, hydrolysable tannin) or quebracho (Q, condensed tannins); overall tannin source intake increased at 5-15 g/kg dry matter (DM) in relation to regular zoo diets. Adaptation periods to the new diets were >2 months. Additional data were taken from one hitherto unpublished study. Data were compared to measurements in the same animals on their regular zoo diets. All animals accepted the new diets without hesitation. There was no influence of tannin supplementation on digestion coefficients of DM and its constituents, or faecal concentrations of short-chain fatty acids or lactate. Water intake did not increase during tannin supplementation. Should the inclusion of dietary tannin sources be an objective in the development of diets for captive rhinoceroses, moderate doses such as used in this study are unlikely to cause relevant depressions of digestive efficiency and will not interfere with bacterial fermentation in a relevant way.     

Serial temperature monitoring and comparison of rectal and muscle temperatures in immobilized free-ranging black rhinoceros (Diceros bicornis)

Control of body temperature is critical to a successful anesthetic outcome, particularly during field immobilization of wild animals. Hyperthermia associated with exertion can lead to serious and potentially life-threatening complications such as organ damage (including myopathy) and death. Methods for monitoring core body temperature must accurately reflect the physiologic status of the animal in order for interventions to be effective. The goal of this preliminary study was to compare serial rectal and muscle temperatures in field-immobilized black rhinoceros (Diceros bicornis) and evaluate a possible association. Twenty-four free-ranging black rhinoceros were immobilized between February and March of 2010 in Ethosha National Park, Namibia. Pairwise comparisons showed a correlation of 0.73 (95% CI; 0.70-0.75) between rectal and muscle temperature measurements. Results from a multivariable model indicate that muscle temperature readings were, on average, 0.46 degrees C (95% CI; 0.36-0.57 degrees C) higher than rectal temperatures while adjusting for repeated measurements on the same rhinoceros, effect of duration of immobilization, and effect of ambient temperature on rhinoceroses' temperature readings. As immobilization time increased, muscle and rectal temperature values within an individual rhinoceros tended to equilibrate. The overall temperatures decreased by an average of 0.00059 degrees C/min (95% CI; -0.0047 to -0.0035 degrees C/min; P = 0.779). As the ambient temperature at time of immobilization increased by 1 degree C, the average rhinoceros temperature increased by 0.09 degrees C (95% CI; 0.06-0.11 degrees C, P < 0.0001). Higher body temperature creates a potential for cellular damage leading to complications that include myopathy. Methods for monitoring rectal, muscle, and ambient temperatures should be incorporated into anesthetic monitoring protocols for large ungulates, particularly under field conditions.     

Effects of translocation on hematologic parameters of free-ranging black rhinoceros (Diceros bicornis michaeli) in Kenya.

Management of the endangered black rhinoceros (Diceros bicornis michaeli) in Africa frequently involves translocation. These procedures are not without risk, and protocols must be critically examined. Hematologic analyses can be used to evaluate the effects of translocation on animal health. Hematologic data obtained during routine translocation of free ranging black rhinoceros (n = 74) in Kenya between 1991 and 1995 were examined, and subsets of data from rhinoceros (n = 43) that were translocated to different regions of Kenya were compared. All animals showed an increase in total blood protein. Animals transported for longer periods and to lower altitude zones with higher ambient temperatures and trypanosomiasis developed anemia and showed neutrophilia, lymphopenia (males), and eosinopenia. The changes in packed cell volume (PCV), hemaglobin, and neutrophils were more marked in females, and the PCV drop was more significant in subadults. The red cell changes were most probably pathologic, involving the loss of red cells from circulation through sequestration or hemorrhage. The changes in white cell parameters are consistent with the effect of endogenous corticosteroids as a result of stress. Transport and confinement stress might lead to gastric ulceration with hemorrhage. In many animals, exposure to trypanosomes contributes to anemia.     

Antioxidant status of faeces of captive black rhinoceros (Diceros bicornis) in relation to dietary tannin supplementation

In context with the frequent observations of excessive iron (Fe) storage in captive black rhinoceroses (Diceros bicornis), it has been suggested that both an excessive dietary Fe content and a lack of dietary Fe-chelating substances, such as tannins, is the underlying cause. Therefore, studies on the effects of tannin supplementation to captive diet are warranted. Six captive rhinoceroses were fed their normal zoo diet (N), and a similar diet supplemented with either tannic acid (T, hydrolysable tannin) or quebracho (Q, condensed tannins), and the total antioxidant capacity (TAC) was measured as mmol Trolox equivalents per kg fresh faeces. The TAC values on diets N (1.24 +/- 0.39 mmol/kg fresh faeces) and T (1.34 +/- 0.33 mmol/kg fresh faeces) were similar, but significantly higher on diet Q (2.32 +/- 0.61 mmol/kg fresh faeces). In contrast to expectations, faecal TAC increased with increasing faecal Fe, possibly as a result of the fact that the faecal Fe content was positively correlated to the proportion of concentrate feeds in the diet, which also contain antioxidants, such as vitamin E, in addition to Fe. Increased antioxidant status caused by the use of tannin substances could have a beneficial effect on animal health, but if tannins should be incorporated in designed diets, other tannin sources, such as grape pomace should be tested.     

Quantification of Enterobacteriaceae in faeces of captive black rhinoceros (Diceros bicornis) in relation to dietary tannin supplementation

Free-ranging browsing herbivores ingest a range of secondary plant compounds, such as tannins, with their natural diet. As many of these substances have been shown to have antibacterial properties, it could be speculated that a lack of such compounds in captive zoo diets could favour the growth of potentially pathogenic intestinal bacteria. The effect of a supplementation of a conventional diet (N, consisting mainly of grass hay and/or lucerne hay and pelleted compound feeds) fed to eight captive black rhinoceroses (Diceros bicornis) from three zoological institutions with either tannic acid (T), a source of hydrolysable tannins, or quebracho (Q), a source of condensed tannins, was investigated. The number of faecal colony forming units (CFU) of Enterobactericeae was determined by colony count of dilution series from fresh faeces applied to MacConkey agar plates. Tannins were added to the diets at approximately 5-15 g/kg dry matter, depending on the varying intake of roughage and compound feeds by the animals. There was no difference in the number of CFU between diets N (95.0 x 10(5) +/- 225.3 x 10(5)/g fresh faeces) and T (164.3 x 10(5) +/- 225.1 x 10(5)/g fresh faeces); in contrast, diet Q led to a significant reduction in CFU (4.3 x 10(5) +/- 6.5 x 10(5)/g fresh faeces) compared with the other diets. These findings suggest that condensed tannins could have the potential to reduce the number of potentially pathogenic intestinal bacteria, and that the deliberate inclusion of tannin sources in the diets of captive wild animals should be further investigated. The fact that tannic acid, shown to have antibacterial effects in various in vitro studies, did not have an effect in this study, emphasizes that the relevance of tannin supplementation for intestinal health must be verified in vivo.