Serosurvey for selected viral agents in white rhinoceros (Ceratotherium simum) in Kruger National Park, 2007

One hundred serum samples collected from free-ranging white rhinoceros (Ceratotherium simum) in Kruger National Park (KNP) during the 2007 capture season were selected for measurement of antibody levels to several different vector-borne viral agents. These infectious diseases were chosen to compare with an earlier serosurvey that had been conducted in KNP in rhinos during 1987-1997. Positive antibody titers were found against epizootic hemorrhagic disease (EHD) of deer (8%), Bluetongue (BT) (1%), and Rift Valley fever (RVF) (49%). However, none of the 100 animals tested had detected antibody levels to African horse sickness (AHS). These values were in sharp contrast to those measured in the 1987-1997 survey in KNP white rhinos (AHS 60%, EHD 30%, BT 37%, RVF 0%). Vector-borne viral infection prevalence in white rhinos in the same geographical location appears to vary over time and may be important for monitoring presence of pathogens in an ecosystem.     

Stress steroid levels and the short-term impact of routine dehorning in female southern white rhinoceroses (Ceratotherium simum simum)

Rhinoceros populations in Africa are under severe threat as a result of surging poaching rates and risk-mitigation strategies are continuously adapted in an attempt to ensure the survival of the species. This study compared faecal glucocorticoid metabolite (fGCM) levels of two age classes of limited free-ranging female white rhinos with fGCM levels of adult free-ranging female white rhinos. Subsequently, fGCM alterations in the limited free-ranging animals were monitored following routine dehorning as a measure of the animals’ short-term physiological stress response. Baseline fGCM levels differed significantly between tested groups, with both free-ranging and limited free-ranging adult animals showing significantly higher fGCM levels compared with limited free-ranging juvenile females. In contrast, baseline fGCM levels did not differ significantly between limited free-ranging and free-ranging adult individuals. Routine dehorning procedures resulted in a short-term stress response expressed by a significant increase in fGCM levels 48 h post-dehorning, with stress steroid levels returning to pre-dehorning concentrations 72 h after the procedure.     

Reference cardiopulmonary physiologic parameters for standing, unrestrained white rhinoceroses (Ceratotherium simum).

Chemical restraint is an important tool for the management and medical care of both captive and free-ranging rhinoceroses. Current anesthetic protocols for the white rhinoceros (Ceratotherium simum) are reported to cause varying degrees of hypertension, tachycardia, muscular stiffness and fasciculation, acidosis, and, most importantly, respiratory depression with resulting hypoventilation, hypoxia, and hypercapnea. To assist in the assessment and development of new and improved anesthetic techniques for the white rhinoceros, the following cardiopulmonary reference parameters for standing, unrestrained white rhinoceroses were generated (mean +/- standard error [minimum maximum]): heart rate = 39 +/- 0.8 beats/min (32-42), respiratory rate = 19 +/- 0.6 breaths/min (16-23), corrected indirect systolic blood pressure = 160 +/- 2.9 mm Hg (146-183), corrected indirect diastolic blood pressure = 104 +/- 2.3 mm Hg (88-117), corrected indirect mean blood pressure = 124 +/- 2.2 mm Hg (108-135), end tidal CO2 = 45.1 +/- 0.7 mm Hg (41.7-48.0), rectal temperature = 36.8 +/- 0.1 degrees C (36.6-37.2), arterial blood pH = 7.391 +/- 0.007 (7.346-7.431), arterial partial pressure of oxygen = 98.2 +/- 1.4 mm Hg (90.2-108.6), arterial partial pressure of CO2 = 49.0 +/- 0.9 mm Hg (44.4-53.7), base excess = 3.5 +/- 0.4 mmol/L (1.9-5.9), bicarbonate = 29.3 +/- 0.4 mmol/L (27.3-32.2), and arterial hemoglobin oxygen saturation (SaO2) = 97.2 +/- 0.1% (96.6-98.0).     

Pheochromocytoma in a white rhinoceros (Ceratotherium simum)

A 46-yr-old male white rhinoceros (Ceratotherium simum) died during anesthesia following agonal excitation. On postmortem, a well-demarcated 2.5-cm tan mass was identified in the right adrenal gland. Histopathology confirmed the presence of a pheochromocytoma, and elevated levels of epinephrine in serum collected shortly prior to the animal's death, as compared with sera from healthy controls, demonstrated the functional nature of the tumor. Although rare, pheochromocytoma should be considered as a differential diagnosis in cases of suspected hypertension and acute death in rhinos.     

The cardiopulmonary effects of etorphine, azaperone, detomidine, and butorphanol in field-anesthetized white rhinoceroses (Ceratotherium simum).

White rhinoceroses (Ceratotherium simum) anesthetized with etorphine combinations develop severe pathophysiologic changes, including hypoventilation, hypoxemia and metabolic acidosis. The aim of this study was to evaluate the addition of butorphanol to the immobilizing mixture on the cardiopulmonary effects in free-ranging white rhinoceroses darted from the helicopter. In the control group (n=15), the rhinoceroses were anesthetized with etorphine, azaperone, detomidine, and hyaluronidase administered intramuscularly. In the treatment group (n=16), 10-20 mg of butorphanol was added to the combination. Within 10 min of becoming immobile, vital parameters (heart rate, respiratory rate, and temperature) and blood gas analyses were taken, and measurements were repeated after 10 (treatment group) and 20 min (control group). Both groups showed respiratory and metabolic acidosis, hypoxemia, and hypercapnia. In the control group, the arterial partial pressure of oxygen was significantly higher and the alveolar-to-arterial oxygen pressure gradients were significantly lower in all body positions compared with the butorphanol group. Oxygen hemoglobin saturation in the control group was higher than in the butorphanol group only in the lateral position. Improvements in arterial oxygen levels were observed in all animals when placed in sternal recumbency. There were no significant differences in the mean induction times between groups, but the distance the butorphanol group ran was significantly less after darting than in the control group. By adding butorphanol to the immobilizing mixture, no benefits in ventilation were seen; although, size differences make comparisons difficult. Running for a shorter distance during induction could be beneficial in the prevention of severe acid-base imbalances and capture myopathy.     

Neosporosis in a white rhinoceros (Ceratotherium simum) calf

A 16-day-old white rhinoceros calf died suddenly while in excellent condition and showing no obvious previous clinical signs. It was the 9th calf of a mature female kept free-ranging with 11 other rhinoceros as well as various other game species on a 2000 hectare game breeding centre adjacent to the town of Lichtenburg and outlying cattle farmlands in the Northern Province. At post mortem examination, death was ascribed to heart failure. There was marked multifocal to coalescing subacute parasitic myocarditis with numerous protozoan bradyzoite cysts and free tachyzoites present amongst the predominantly round cell inflammatory infiltrate. The coccidian was positively identified as Neospora sp. using both polyclonal and murine monoclonal Neospora caninum antibody immunohistochemistry in the avidin-biotin technique. The parasites stained poorly with Toxoplasma gondii-specific immunoperoxidase staining. Ultrastructurally, a section of a bradyzoite-containing cyst, as well as tachyzoites, were largely but not totally consistent with those described for Neospora caninum. The dam showed no sign of illness. Neosporosis affecting white rhinoceros (Ceratotherium simum) has not previously been reported. A summarised overview of neosporosis from selected publications and a recent review is given.     

Serial chemical restraint for treatment of decubitus ulcers in two neonatal white rhinoceroses (Ceratotherium simum).

Two neonatal white rhinoceroses (Ceratotherium simum) at two zoological institutions were medically managed for wounds characterized by extensive multifocal necrosis of the skin and subcutaneous tissue, associated with decubitus ulcers throughout the body. Wounds resulted from prolonged recumbency due to inability to stand in one case and causes unconfirmed in the other. Both calves were born in cement stalls during winter. Using either butorphanol (i.v. or i.m.) alone or in combination with detomidine (i.m.), serial chemical restraint was conducted over a 6-wk period to facilitate wound care. Anesthesia was well tolerated in both calves, and lesions responded well to medical treatment.     

Morphology of the intestinal tract in the white rhinoceros (Ceratotherium simum)

The intestinal tract of the white rhinoceros (Ceratotherium simun) was dissected. We observed a simple structure for the small intestine, duodenum, jejunum and ileum, and a well-developed large intestine, cecum, colon and rectus. The cecum consisted of a small chamber, whereas the colon was much enlarged; notably larger than that of the domesticated horse, which belongs to the same order, Perissodactyla. This suggests that in the white rhinoceros the cecum may be functionally replaced by the well-developed colon which may act as the main fermentation tank in this animal.     

Incidence of ryegrass staggers in white rhinoceros (Ceratotherium simum) at Auckland Zoo

Abstract

Extract

Most perennial ryegrass (Lolium perenne) plants in pastures in New Zealand contain a naturally occurring fungal endophyte, Neotyphodium lolii. Endophyte-infected perennial ryegrass produces alkaloids that vary in concentration during the year. Some alkaloids enhance the persistence and productivity of ryegrass pastures by protecting them against insect attack. However, when other alkaloids are consumed they can reduce animal performance and lead to health problems. The alkaloid lolitrem B, for example, causes the neuromuscular disorder ryegrass staggers (Fletcher et al 1999 Fletcher, LR, Sutherland, BL and Fletcher, CG. 1999. “The impact of endophyte on the health and productivity of sheep grazing ryegrass-based pastures”. In Ryegrass endophyte: an essential New Zealand symbiosis Grassland Research and Practice Series Edited by: Woodfield, DR and Matthew, C. Vol. 7, 11–17.  [Google Scholar]). Clinical symptoms of ryegrass staggers in animals range from slight muscular tremors through to staggering and complete collapse. Severely affected animals create management problems and are prone to accidental death. Outbreaks occur sporadically, particularly in summer and autumn and affect sheep, cattle, deer, horses, llamas (Lama glama) and alpaca (Lama pacos). Lolitrem B appears to be a stable compound, which tends to be concentrated in the leaf sheath at the base of the ryegrass plant and in the seed-heads (di Menna et al 1992 di Menna, ME, Mortimer, PH, Prestidge, RA, Hawkes, AD and Sprosen, JM. 1992. Lolitrem B concentrations, counts of Acremo ni um lolii hyphae, and the incidence of ryegrass staggers in lambs on plots of A. lolii-infected perennial ryegrass. New Zealand Journal of Agricultural Research, 35: 211–217. [Taylor &; Francis Online], [Web of Science ®] , [Google Scholar]; Keogh et al 1996 Keogh, RG, Tapper, BA and Fletcher, RH. 1996. Distributions of the fungal endophyte Acremonium lolii, and of the alkaloids lolitrem B and peramine, within perennial ryegrass. New Zealand Journal of Agricultural Research, 39: 121–127. [Taylor &; Francis Online], [Web of Science ®] , [Google Scholar]). Hay made from endophyte-infected perennial ryegrass contains large numbers of seed-heads and lolitrem B concentrations can be high, especially if it is made in late summer or autumn and, consequently, animals fed such hay are at risk of developing ryegrass staggers.     

Diagnosis and management of a patent urachus in a white rhinoceros calf (Ceratotherium simum simum).

A 10-day-old female southern white rhinoceros calf (Ceratotherium simum simum) was diagnosed with a patent urachus after urine was observed dribbling from the umbilicus. After being separated from its mother, the animal was sedated with i.m. butorphanol and anesthetized with isoflurane in oxygen for surgical correction of the patent urachus. Mild postoperative complications involved seroma formation and partial skin incision dehiscence, which necessitated three follow-up immobilizations for reevaluation and treatment of the surgical site. Histopathology did not reveal an infectious etiology as the cause for the complications or for the patent urachus. The etiology of the patent urachus in this animal remains undetermined. This report represents the first documented case of a patent urachus in a white rhinoceros.     

Vesiculobullous skin reaction temporally related to firocoxib treatment in a white rhinoceros (Ceratotherium simum)

A 40 yr-old female white rhinoceros (Ceratotherium simum) suffered from chronic nail-bed abscesses. Due to worsening of clinical signs, the animal's nonsteroidal anti-inflammatory treatment was switched to firocoxib. Approximately 7 days after this change, the animal developed multifocal vesicles and bullae along the lateral aspects of the thorax and abdomen, the dorsum, and the proximal limbs. Cytology and culture did not identify an infectious etiology. Histologically, the lesions consisted of a severe, subacute vesiculobullous dermatitis with intraepidermal to subepidermal clefting with areas of individual keratinocyte necrosis and minor neutrophilic epidermal infiltrates. These findings are similar to those seen in some drug reactions in people; therefore an adverse drug reaction to the firocoxib was suspected.     

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.     

Pharmacokinetics of an intravenous and oral dose of enrofloxacin in white rhinoceros (Ceratotherium simum)

South Africa currently loses over 1000 white rhinoceros (Ceratotherium simum) each year to poaching incidents, and numbers of severely injured victims found alive have increased dramatically. However, little is known about the antimicrobial treatment of wounds in rhinoceros. This study explores the applicability of enrofloxacin for rhinoceros through the use of pharmacokinetic‐pharmacodynamic modelling. The pharmacokinetics of enrofloxacin and its metabolite ciprofloxacin were evaluated in five white rhinoceros after intravenous (i.v.) and after successive i.v. and oral administration of 12.5 mg/kg enrofloxacin. After i.v. administration, the half‐life, area under the curve (AUC_tot), clearance and the volume of distribution were 12.41 ± 2.62 hr, 64.5 ± 14.44 μg ml^?1 hr^?1, 0.19 ± 0.04 L h^?1 kg^?1, and 2.09 ± 0.48 L/kg, respectively. Ciprofloxacin reached 26.42 ± 0.05% of the enrofloxacin plasma concentration. After combined i.v. and oral enrofloxacin administration oral bioavailability was 33.30 ± 38.33%. After i.v. enrofloxacin administration, the efficacy marker AUC₂₄: MIC exceeded the recommended ratio of 125 against bacteria with an MIC of 0.5 μg/mL. Subsequent intravenous and oral enrofloxacin administration resulted in a low Cmax: MIC ratio of 3.1. The results suggest that intravenous administration of injectable enrofloxacin could be a useful drug with bactericidal properties in rhinoceros. However, the maintenance of the drug plasma concentration at a bactericidal level through additional per os administration of 10% oral solution of enrofloxacin indicated for the use in chickens, turkeys and rabbits does not seem feasible.     

Reliability of pulse oximetry at four different attachment sites in immobilized white rhinoceros (Ceratotherium simum)

ObjectivesTo determine the reliability of peripheral oxygen haemoglobin saturation (SpO₂), measured by a Nonin PalmSAT 2500A pulse oximeter with 2000T transflectance probes at four attachment sites (third eyelid, cheek, rectum and tail), by comparing these measurements to arterial oxygen haemoglobin saturation (SaO₂), measured by an AVOXimeter 4000 co-oximeter reference method in immobilized white rhinoceros (Ceratotherium simum).Study designRandomized crossover study.AnimalsA convenience sample of eight wild-caught male white rhinoceros.MethodsWhite rhinoceros were immobilized with etorphine (0.0026 ± 0.0002 mg kg^–1, mean ± standard deviation) intramuscularly, after which the pinna was aseptically prepared for arterial blood sample collection, and four pulse oximeters with transflectance probes were fixed securely to their attachment sites (third eyelid, cheek, rectum and tail). At 30 minutes following recumbency resulting from etorphine administration, the animals were given either butorphanol (0.026 ± 0.0001 mg kg^–1) or an equivalent volume of saline intravenously. At 60 minutes following recumbency, insufflated oxygen (15 L minute^–1 flow rate) was provided intranasally. In total, the SpO₂ paired measurements from the third eyelid (n = 80), cheek (n = 67), rectum (n = 59) and tail (n = 76) were compared with near-simultaneous SaO₂ measurements using Bland-Altman to assess bias (accuracy), precision, and the area root mean squares (ARMS) method.ResultsCompared with SaO₂, SpO₂ measurements from the third eyelid were reliable (i.e., accurate and precise) above an SaO₂ range of 70% (bias = 1, precision = 3, ARMS = 3). However, SpO₂ measurements from the cheek, rectum and tail were unreliable (i.e., inaccurate or imprecise).Conclusions and clinical relevanceA Nonin PalmSAT pulse oximeter with a transflectance probe inserted into the space between the third eyelid and the sclera provided reliable SpO₂ measurements when SaO₂ was > 70%, in immobilized white rhinoceros.     

The prevalence of blood parasites in helmeted guineafowls, Numida meleagris, in the Kruger National Park

Bloodsmears were taken from separate groups of five helmeted guineafowls, Numida meleagris, shot at approximately monthly intervals at Skukuza and near Lower Sabie in the Kruger National Park during the period August 1988 to August 1990. Ninety-eight (86%) of 114 guineafowls had single or multiple infections of Aegyptianella sp., Haemoproteus pratasi, Hepatozoon sp., Leucocytozoon neavei, Plasmodium circumflexum and Trypanosoma numidae. The apparent seasonal prevalence of Aegyptianella sp., H. pratasi and L. neavei, the three most commonly occurring parasites (42%, 49% and 56% of birds infected respectively), is probably dependent on the presence of their respective vectors.     

Captive breeding of the white rhinoceros, Ceratotherium simum, and the Cape buffalo, Syncerus caffer

Breeding records of 40 white rhinoceros and 155 Cape buffalo were analysed. Three rhinoceros cows bred in captivity, themselves conceived for the first time at 84, 87 and 95 months of age, respectively. Rhinoceros cows breed throughout the year. There is no evidence of a relationship between calving interval and month of birth. Calving intervals were normally distributed about the mean of 34 months and there were no significant differences between bulls, cows or sex of calf. There was no difference in the sex ratio of calves born to young cows nor older cows. The male:female ratio of the calves was 1:1. Younger cows did not have shorter birth intervals. Although captive Cape buffaloes breed throughout the year, there is a preponderance of births in midsummer. There was some evidence that larger cows produce heavier calves and that season of birth may influence birth weight. Male calves weighed 41.20 +/- 0.68 kg vs 39.00 +/- 0.73 kg (range 24-60 kg) for female calves but this difference was not significant. Calving intervals were normally distributed about the mean of 395 days and the male:female ratio of the calves was 1:1.2.