Steatitis in wild sharptooth catfish, Clarias gariepinus (Burchell), in the Olifants and lower Letaba Rivers in the Kruger National Park, South Africa

Large numbers of adult Nile crocodiles, Crocodylus niloticus (Laurenti), died from pansteatitis during autumn and winter 2008 in the lower Letaba and Olifants River gorge in the Kruger National Park, South Africa. Consequently, the health status of fish from these waters was investigated. The study presents the pathological findings in fish inhabiting these rivers within the boundaries of the Park. Changes typical of steatitis were diagnosed in many of the larger specimens of sharptooth catfish, Clarias gariepinus (Burchell), caught within the Olifants River gorge. These fish carried large amounts of mesenteric fat with characteristic small brown granulomata within the adipose tissue. Necrosis and inflammation of the adipose tissues, with characteristic ceroid accumulation within the resultant granulomata and the associated aggregation of ceroid‐containing macrophages, were demonstrated histologically and were typical of steatitis. Other changes included mild thickening and pallor of the gill tissues and swollen, orange, fatty livers. Focal hepatic lipidosis was demonstrated histologically, and special stains revealed storage of large amounts of iron in the livers. Blood smears revealed chromatin clumping in erythrocyte nuclei and nuclear and cell membrane irregularities. This is the first record of steatitis in wild‐caught C. gariepinus.     

Incidence and intensity of tree infestation by the mistletoe Erianthemum dregei (Eckl. & Zeyh.) V. Tieghem in Durban,South Africa

Relatively few studies have investigated mistletoe infestation of tree species in urban settings, and even fewer considered infestation of alien tree species. Here, mistletoe infestation incidence and intensity were studied in Durban, South Africa. The relationship of infestation to tree CBH and height was examined in detail for the mistletoe species Erianthemum dregei. Although E. dregei is known to have a wide range of host taxa, we report E. dregei infestation on 27 new host species for the first time. E. dregei occurred on 30 host species with a preference for the alien host tree Melia azedarach in our study area. The relationship between infestation and CBH indicated that the trees (irrespective of species) of ≥200 cm were more susceptible to the mistletoe attack. The implications of this pattern, as well as those of high host diversity and especially of infestation of alien trees are discussed in a conservation perspective.     

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.     

Comparison of the lipid properties of healthy and pansteatitis‐affected African sharptooth catfish,Clarias gariepinus (Burchell), and the role of diet in pansteatitis outbreaks in the Olifants River in the Kruger National Park,South Africa

Pansteatitis has been identified in wild populations of sharptooth catfish, Clarias gariepinus (Burchell), and Nile crocodiles, Crocodylus niloticus Laurenti, inhabiting the same waters in the Olifants River Gorge in the Kruger National Park, South Africa. Mesenteric and pectoral fat tissue was investigated microscopically and by fatty acid analysis in healthy and pansteatitis‐affected catfish from both captive and wild populations. Variation in fatty acid composition between pectoral and mesenteric fat was noted. Composition of mesenteric fat differed between fish from various localities as a result of differences in diet. Pansteatitis in the captive population, resulting from ingestion of high amounts of dietary oxidized fat, reflected higher levels of unsaturated fatty acids within the mesenteric fat. Mesenteric fat of pansteatitis‐affected wild catfish was characterized by an increase in moisture content, a decrease in fat content and a decrease in stearic and linoleic acids. The n‐3 to n‐6 fatty acid ratio of mesenteric fat was higher in pansteatitis‐affected wild catfish than in healthy catfish from the same locality, reflecting higher polyunsaturated fat intake by pansteatitis‐affected fish. The possible role of alien, invasive, phytoplankton‐feeding silver carp, Hypophthalmichthys molitrix (Valenciennes), in the aetiology of pansteatitis in both catfish and crocodiles in the Olifants Gorge is discussed.     

Piroplasm parasites of white rhinoceroses (Ceratotherium simum) in the Kruger National Park, and their relation to anaemia

As part of a larger survey to map the geographical distribution of Babesia and Theileria parasites in the southern African rhinoceros population, white rhinoceroses were sampled during routine immobilisations in the Kruger National Park. Polymerase chain reaction (PCR) and reverse line blot (RLB) hybridisation assays were used to screen for the presence of piroplasms and complete blood counts were used to assess associated changes in clinical parameters. Of the 195 rhinoceroses sampled, 71 (36.4 %) tested positive for the presence of Theileria bicornis, with no significant change in the haematological parameters measured, while 18 (9.2 %) tested positive for Theileria equi. None of the rhinoceroses sampled tested positive for Babesia bicornis, a parasite associated with mortalities in black rhinoceroses.