Dissociative anaesthesia in free-ranging male koalas and selected marsupials in captivity

Forty seven free-ranging, adult, male koalas were captured and administered an intramuscular injection of the dissociative anaesthetic, Telazol (tiletamine HCl plus zolazepam HCl), at dose rates of 5.0 to 7.7 mg/kg body weight. Anaesthesia induction was rapid and smooth and resulted in a surgical plane of anaesthesia lasting 30 to 45 min. There was no depression of heart rate or respiration. Mild salivation occurred in most animals, but was not a problem because the swallowing reflex was retained. There was no mortality or morbidity and the anaesthesia level was sufficient to allow electroejaculation and multiple blood sampling with no apparent animal discomfort. For 10 of 19 males in which anaesthesia was required for a 90 min protocol, a supplementary Telazol injection (average, 2.5 mg/kg) was necessary. All koalas recovered completely within 3 to 4 h of the initial injection. The results suggest that the optimal Telazol dosage for the adult male koala is 7.0 mg/kg body weight. The retrospective analysis of 259 anaesthesia records involving 14 species indicated that Telazol was equally effective and safe in other captive marsupials.     

Gastrointestinal diseases of foals

Few foals escape gastrointestinal disease during the first weeks of life. Diarrhea is an extremely common problem; fortunately, however, it is usually mild and self-limiting. When it is not, the underlying cause is often an infectious agent, such as rotavirus or Salmonella spp. Our understanding of many of the infectious agents causing neonatal diarrhea is far from complete. Gastric and duodenal ulcers are a less common disease of neonatal foals. There has been an apparent increase in the incidence of ulcer disease in foals during the past few years. The most effective way of decreasing serious gastrointestinal disease in foals is through the use of good management practices. Environmental and dietary stress must be minimized, and good hygienic practices should be followed. Unfortunately, the needs of the neonate are often ignored, while attention is focused on the mare during the breeding season.     

Metastasis of bile ductule carcinoma in a cow

An 8-year-old Holstein cow was referred with a history of weight loss, poor milk production, and hyperfibrinoginemia. Laboratory evaluation showed high gamma-glutamyltransferase activity, prolonged sulfobromophthalein clearance half-time, and prolonged prothrombin and partial thromboplastin times. Multiple firm nodules with histologic evidence of bile ductule carcinoma were found on exploratory laparotomy and liver biopsy. Pulmonary and lymph node tumor metastases were extensive. Tumor development in this case could not be associated with any of the known contributing factors in ruminants. This case demonstrates the extensive metastatic potential of this tumor and nonspecific signs with which bovine hepatic disease can be manifested.     

Respiratory support techniques in foals in a newborn intensive care unit for large animals]

Various techniques for support and control of respiration in neonatal foals are described. It is crucial to evaluate respiration through frequent arterial blood gas analysis. Details for blood sampling from the metatarsal arteries and interpretation of results are provided. Typical diseases in newborn foals, which cause hypoxemia and/or hypercapnia and can be indications for respiratory support are apnea, hypopnea, pulmonary atelectasis, surfactant deficiency, meconium-, fetal fluid- and milk aspiration, maladjustment syndrome, cardiovascular abnormalities, anemia, airway obstruction, compromised lung expansion, increased abdominal pressure and pneumonias. Oxygen insufflation can be delivered through an intranasal tube. Positive pressure ventilation is best accomplished via an endotracheal tube. A nasogastric tube is inserted for enteral nutrition, application of drugs and checking for gastric reflux. Details for insertion of endotracheal and nasogastric tubes are given. Positive pressure ventilation can be achieved by manual ventilation with a rebreathing resp. resuscitator bag and mechanical ventilation with a respirator. Management and control of mechanical ventilation as well as intensive care and monitoring of foals are described.     

Comparison of the effects of intragastric infusions of equal volumes of water, dioctyl sodium sulfosuccinate, and magnesium sulfate on fecal composition and output in clinically normal horses.

A Latin square design was used to compare the effects of laxatives and a corresponding volume of water on gastrointestinal tract function in 4 healthy horses. Horses were intragastrically infused with each of the following: dioctyl sodium sulfosuccinate (DSS; 50 mg/kg of body weight); magnesium sulfate (0.5 g/kg--low dosage); magnesium sulfate (1.0 g/kg--high dosage); and an equal volume of water (6 L) given as a control infusion. From 5 to 33 hours after the high dosage of magnesium sulfate, feces were slightly softer than usual in all horses. In 1 horse, DSS caused mild colic, hyperpnea, and diarrhea from 0.3 to 3 hours after administration. After all laxative treatments and the control infusion, fecal output, fecal water, number of defecations, and fecal water percentage were greater during the first 6 and 12 hours, compared with each subsequent 6-hour period (P less than 0.05). The high dosage of magnesium sulfate had greater effect on fecal output and fecal water than did the low dosage and control infusion (P less than 0.05). However, this effect preceded arrival of the liquid transit marker, polyethylene glycol, and magnesium at their highest concentrations in feces by 12 to 18 hours. Compared with the control infusion, none of the laxative treatments affected excretion of polyethylene glycol and plastic particulate markers, nor did they increase water consumption. It was concluded that the response to intragastric infusions may involve reflex mechanisms in the gastrointestinal tract and that these responses could be used for treatment of colon impactions.(ABSTRACT TRUNCATED AT 250 WORDS)     

Estimating evapotranspiration in semi-arid rangelands: connecting reference to actual evapotranspiration and the role of soil evaporation

In a context of water scarcity, efforts to increase landscape production should focus on improving water productivity. This requires an appreciation of the various components of evapotranspiration (ET), including soil evaporation (E_s) because the latter reflects ‘unproductive’ water loss. Both complex and simple algorithms have been developed to determine ET. In data scarce areas, developing and testing parsimonious algorithms is useful. This study sought to improve a simple single layer ET model by incorporating an E_s component. Empirical methods were also explored to predict ET from vegetation indices (VIs), leaf area index (LAI) and reference evapotranspiration (ET₀). A large aperture scintillometer and an eddy covariance (EC) system were used to validate the proposed algorithm at three sites over Grasslands and Albany Thicket biomes in the Eastern Cape, South Africa. There was good agreement between the observed and predicted ET with RMSE of 0.30–0.58 mm d^?1 when average daily observed ET was 0.43–3.24 mm. The VIs had moderate correlations with the observed data due to the significant role played by E_s (65%–84%) across the sites and stomatal conductance at the Albany Thicket site. The simple algorithms developed would make determining ET easier in data scarce regions.     

Aboveground biomass production of a semi-arid southern African savanna: towards a new model

Following a field campaign to determine the species composition, canopy cover, aboveground annual production and leaf area index (LAI) of the semi-arid savanna of north-western Namibia, we present a production model that can be used by graziers to determine the livestock carrying capacity. The model predicts the annual aboveground net primary production (ANPP) from regression equations of canopy cover by annual production fraction for plant functional classes. We tested the output of the model against another fully independent net primary production (NPP) model, namely the MODIS NPP product. The mean MODIS NPP for the 29 sites was 343 ± 22?kg dry matter (DM) ha^?1 y^?1 as opposed to 285 ± 142?kg DM ha^?1 y^?1 for the fAP model that used the regression method (p < 0.01). As a proof of concept, these landscape-scale ANPP values are used to calculate a recommended livestock carrying capacity for the Ehirovipuka Communal Conservancy, a 1 980 km² communal area with both wildlife and livestock populations. In addition, we also provide details of a field method for predicting landscape-scale LAI from line transect data. This approach can be used to ground reference the LAI values generated from the MODIS LAI product.     

Feeding ecology of four livestock species under different management in a semi-arid pastoral system in South Africa

The Leliefontein communal area in Namaqualand is grazed by mixed species herds that have multiple benefits for pastoralists. This study assessed how the management (herding and free-ranging) of different livestock herds affects their feeding ecology during the wet and dry seasons in a semi-arid shrubland. By using direct observations of livestock grazing in the field, we established their habitat preferences, diet selection and resources overlap. Results indicate that all free-ranging livestock can be considered grazers with cattle being selective. When sheep are herded, they tend to be more generalist feeders and herded goats are browsers. Livestock diet selection and forage preferences are largely linked to the habitats in which they graze and browse. Dietary overlap is highest between free-ranging livestock irrespective of season, whereas herded livestock are able to consume a food source with little potential competition from other livestock. Although the wet-season annual forage resources are able to sustain the livestock population in Leliefontein, this study concludes that the overdependence on annual vegetation would make livestock vulnerable during drought periods when forage production is low.