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.     

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.     

Standing laparoscopic-guided uterine biopsy in a southern white rhinoceros (Ceratotherium simum simum).

Transrectal ultrasonography of a 35-yr-old captive female southern white rhinoceros (Ceratotherium simum simum) with a history of chronic mucohemorrhagic vulvar discharge revealed right transmural uterine horn enlargement. Abdominal laparoscopic surgery, although extremely difficult because of inadequate instrumentation, permitted uterine visualization and biopsy. Standing anesthesia, incorporating butorphanol and azaperone together with local anesthetic infiltration, facilitated the laparoscopy. A leiomyoma was suspected on the basis of history, physical examination, ultrasonographic appearance, and histopathology. Prior rhinoceros laparoscopies have failed, primarily from limitations imposed by recumbency.     

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.     

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.     

Successful treatment of a squamous cell carcinoma in a white rhinoceros, Ceratotherium simum

A captive 33-year-old male white rhinoceros with seasonal dermatitis was diagnosed with a malignant squamous cell carcinoma on the right flank. Staphylococcus aureus was cultured from the skin lesions. No fungal or yeast was isolated. The dermatitis was treated with a combination of oral antibiotics (trimethoprim-sulphadiazine) and topically with weekly chlorhexidine washes and a mixture of a zinc oxide, balsam peru and bismuth oxide cream. Under azaperone and butorphanol anaesthesia, the skin tumour was surgically removed. The tumour was excised with wide margins and allowed to heal by secondary intention as primary wound closure was not possible. A post-mortem performed 2 years later for an unrelated condition revealed no metastases or recurrence of the skin tumour. It was presumed that chronic irritation or trauma may have contributed to the development of the skin tumour. This is the first detailed report of the successful treatment of a squamous cell carcinoma not associated with the horn in a rhinoceros.     

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.     

Anesthetic management of a white rhinoceros (Ceratotherium simum) undergoing an emergency exploratory celiotomy for colic

ObservationsA 26-year-old male white rhinoceros (Ceratotherium simum), weighing approximately 2000 kg was anesthetized for an exploratory celiotomy. Sedation was achieved with intramuscular butorphanol (0.04 mg kg^?1) and detomidine (0.025 mg kg^?1) and induction of anesthesia with intravenous glyceryl guaiacolate (50 g) and three intravenous boluses of ketamine (200 mg, each); the trachea was then intubated and anesthesia maintained with isoflurane in oxygen using a circle breathing system. Positioning in dorsal recumbency for the surgery and later in sternal recumbency for the recovery represented challenges that added to the prolonged anesthesia time and surgical approach to partially correct an impaction. The rhinoceros recovered uneventfully after 10.4 hours of recumbency.ConclusionsAnesthetic management for an exploratory celiotomy with a midline approach is possible in rhinoceroses, although planning and extensive staff support is necessary to adequately position the patient.     

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.     

Conjunctival habronemiasis in a square‐lipped rhinoceros (Ceratotherium simum)

A captive female square‐lipped rhinoceros born in 1993 had been showing intermittent signs of bilateral conjunctivitis and conjunctival proliferation since 1998. Periodic improvement was noted, especially in winter, but overall the condition had deteriorated over the years. Treatment with various topical, intralesional, and systemic antibiotics and glucocorticosteroids was largely ineffective, as were repeated dewormings. No primary cause for these lesions was found in biopsies taken in 2000 and 2006, although a severe infiltrate of numerous eosinophils was observed in the latter. As the condition worsened, secondary corneal changes were noted, and eventually vision was lost due to proliferative conjunctival tissue. Aggressive resection of the proliferating tissue in 2013 restored vision and submitted biopsies yielded a diagnosis of severe allergic conjunctivitis, eosinophilic granuloma, and habronematid (Habronema or Draschia) larval infection. As no other rhinoceros in the herd was affected, including two calves born to the patient who were in close contact with their mother, it was concluded the presentation was most likely due to a hypersensitivity reaction to the dead or dying larvae. Fly repellent is now regularly applied around the eye of this rhinoceros, and a protective face mask has been fitted. Ongoing periodic relapses are treated with oral ivermectin, topical antibiotics, and steroids.     

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.     

Severe hypoxaemia in field-anaesthetised white rhinoceros (Ceratotherium simum) and effects of using tracheal insufflation of oxygen

White rhinoceros anaesthetised with etorphine and azaperone combination develop adverse physiological changes including hypoxia, hypercapnia, acidosis, tachycardia and hypertension. These changes are more marked in field-anaesthetised rhinoceros. This study was designed to develop a technique to improve safety for field-anaesthetised white rhinoceros by tracheal intubation and oxygen insufflation. Twenty-five free-ranging white rhinoceros were anaesthetised with an etorphine and azaperone combination for translocation or placing microchips in their horns. Once anaesthetised the rhinoceros were monitored prior to crating for transportation or during microchip placement. Physiological measurements included heart and respiratory rate, blood pressure and arterial blood gas samples. Eighteen rhinoceros were intubated using an equine nasogastric tube passed nasally into the trachea and monitored before and after tracheal insufflation with oxygen. Seven rhinoceros were not intubated or insufflated with oxygen and served as controls. All anaesthetised rhinoceros were initially hypoxaemic (percentage arterial haemoglobin oxygen saturation (%O2Sa) = 49% +/- 16 (mean +/- SD) and PaO2 = 4.666 +/- 1.200 kPa (35 +/- 9 mm Hg)), hypercapnic (PaCO2 = 8.265 +/- 1.600 kPa (62 +/- 12 mm Hg)) and acidaemic (pHa = 7.171 +/- 0.073 ). Base excess was -6.7 +/- 3.9 mmol/l, indicating a mild to moderate metabolic acidosis. The rhinoceros were also hypertensive (systolic blood pressure = 21.861 +/- 5.465 kPa (164 +/- 41 mm Hg)) and tachycardic (HR = 107 +/- 31/min). Following nasal tracheal intubation and insufflation, the %O2Sa and PaO2 increased while blood pHa and PaCO2 remained unchanged. Tracheal intubation via the nose is not difficult, and when oxygen is insufflated, the PaO2 and the %O2Sa increases, markedly improving the safety of anaesthesia, but this technique does not correct the hypercapnoea or acidosis. After regaining their feet following reversal of the anaesthesia, the animals' blood gas values return towards normality.     

Cloning, sequencing and expression of white rhinoceros (Ceratotherium simum) interferon-gamma (IFN-gamma) and the production of rhinoceros IFN-gamma specific antibodies

Bovine tuberculosis (BTB) is endemic in African buffalo (Syncerus caffer) in the Kruger National Park (KNP). In addition to buffalo, Mycobacterium bovis has been found in at least 14 other mammalian species in South Africa, including kudu (Tragelaphus strepsiceros), Chacma baboon (Papio ursinus) and lion (Panthera leo). This has raised concern about the spillover into other potentially susceptible species like rhinoceros, thus jeopardising breeding and relocation projects aiming at the conservation of biodiversity. Hence, procedures to screen for and diagnose BTB in black rhinoceros (Diceros bicornis) and white rhinoceros (Ceratotherium simum) need to be in place. The Interferon-gamma (IFN-gamma) assay is used as a routine diagnostic tool to determine infection of cattle and recently African buffalo, with M. bovis and other mycobacteria. The aim of the present work was to develop reagents to set up a rhinoceros IFN-gamma (RhIFN-gamma) assay. The white rhinoceros IFN-gamma gene was cloned, sequenced and expressed as a mature protein. Amino acid (aa) sequence analysis revealed that RhIFN-gamma shares a homology of 90% with equine IFN-gamma. Monoclonal antibodies, as well as polyclonal chicken antibodies (Yolk Immunoglobulin-IgY) with specificity for recombinant RhIFN-gamma were produced. Using the monoclonals as capture antibodies and the polyclonal IgY for detection, it was shown that recombinant as well as native white rhinoceros IFN-gamma was recognised. This preliminary IFN-gamma enzyme-linked immunosorbent assay (ELISA), has the potential to be developed into a diagnostic assay for M. bovis infection in rhinoceros.     

The relationship between vaginal electrical impedence and hormone profiles during pregnancy and parturition of a white rhinoceros (Ceratotherium simum simum).

In this study, an attempt was made to use vaginal electrical impedance to predict calving in a female white rhinoceros (Ceratotherium simum simum) and to determine the relationship between vaginal electrical impedance and hormonal profiles during pregnancy. The principle behind vaginal electrical impedance is that a change in the ionic balance of vaginal and cervical mucus occurs in response to changes in reproductive hormones. Three times weekly vaginal electrical impedance readings and fecal samples were collected from midgestation to calving (a 6-mo period). The extracted fecal samples were analyzed for immunoreactive estrogens, progestagens, and corticoids by RIA. Vaginal electrical impedance readings did not decrease before calving but remained consistent throughout the last 140 days of pregnancy. Fecal progestagens in the white rhinoceros decreased between day 17 and day 1 before calving, whereas estrogens increased between 4 and 2 mo before calving, with an additional increase occurring 1 mo before calving. Fecal corticoids increased 5 mo before calving, slowly declined, and increased again within 3 wk before calving. A decline in vaginal electrical impedance was noted 168 days before calving and remained at low levels for 4 wk. At the time of this decrease, the female became aggressive toward the male and began lactating. Fecal progestagens and estrogens did not change during this time; however, fecal corticoids increased as vaginal electrical impedance readings returned to normal along with her behavior and cessation of lactation. In summary, the use of vaginal electrical impedance could not predict parturition in the white rhinoceros. However, an anomaly occurred during pregnancy that was supported by vaginal electrical impedance readings, a change in female behavior, premature lactation, and a subsequent increase in fecal corticoids. The etiology of this physiological anomaly is unknown, yet it did not compromise pregnancy.     

Remote assessment of stress in white rhinoceros (Ceratotherium simum) and black rhinoceros (Diceros bicornis) by measurement of adrenal steroids in feces.

This study monitored fecal cortisol and corticosterone levels in 14 black rhinoceroses (Diceros bicornis) and in seven white rhinoceroses (Certotherium simum) under various conditions of captivity, including translocation. Free cortisol and free corticosterone were measured in methylene chloride extracts of feces, using high-performance liquid chromatography (HPLC). The extraction-assay method was validated for quantitative measurement of these hormones by mass spectroscopy analysis, chemical derivitization, and radiolabel tracking and recovery. Both cortisol and corticosterone were extractable from feces and routinely detectable by HPLC. In three nonstressed, captivity-adapted white rhinoceroses monitored across 21 days of routine activity, fecal cortisol ranged from 2.0 to 7.3 ng/g dry feces and corticosterone from 4.0 to 10.8 ng/g dry feces, with no observable trend. Matched plasma, urine, and fecal samples in these rhinoceroses yielded corticosterone:cortisol ratios of 2.0:1.0, 2.7:1.0, and 2.2:1.0, respectively. Both black rhinoceroses (n = 5) and white rhinoceroses (n = 4) exhibited higher fecal cortisol (6.9- to 10.0-fold) and corticosterone (3.2- to 4.5-fold) levels in association with restraint-translocation than in limited free-roaming conditions. In five black rhinoceroses monitored across 6 wk after release from translocation, fecal levels of both cortisol and corticosterone decreased significantly between week 1 and weeks 4-6. In general, cortisol and corticosterone paralleled each other, with cortisol exhibiting a greater range of response. Measurement of either hormone in feces appears to be reliable for adrenal axis monitoring in the white and the black rhinoceroses.