Gifblaar Dichapetalum Cymosum 1982.Pdf
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MAWQUA. VOL. 13. NO. l. I982ISg-70) 59 Antelope and poisonous plant S: CONTENTS 1 Introduction ....................... 59 1. Gifblaar Dichapetalum 2 Experiment 1: Voluntary intake .......... 60 cymosum (Hooker) 2.1 Procedure ..................... 60 Engler & Prantl 2.2 Results ........................ 61 containing monofluoroacetate 3 Experiment 2: Toxicity trials ............ 61 3.1 General procedure ................ 61 3.2 Goats ......................... 62 by 3.2.1 Dosing .................... 62 P. A. Basson 3.2.2 Results .................... 62 Division of Veterinary Services, 3.3 Eland ......................... 63 Grootfontein, 3.3.1 Dosing .................... 63 South West ~Frica/Namibia 3.3.2 Results .................... 63 3.4 Kudu 64 A. G. Norval ......................... 3.4.1 Dosing .................... 64 Division of Veterinary Services. Okahandja, 3.4.2 Results .................... 64 South West AfricdNamibia 3.5 Gernsbok ...................... 66 3.5.1 Dosing .................... 66 J. M. Hofmeyr 3.5.2 Results .................... 66 Etosha Ecological Institute, 3.6 Springbok ...................... 66 Q kaukuejo, 3.6.1 Dosing 66 South West Africamamibia .................... 3.6.2 Results .................... 66 H. Ebedes 3.7 Pathology ...................... 66 National Zoological Gardens, 3.7.1 Antelope ................... 66 Pretoria, 3.7.2 Goats ..................... 67 Republic of South Africa 3.8 Histopathology .................. 67 and 4 Discussion and conclusions ............. 68 R. Anitra Schultz 5 Acknowledgements ................... 69 Veterinary Research Institute, Onderstepmq 6 References.. ....................... 69 Republic of South Africa Received: 6 July 1981 ABSTRACT Ten tame eland (Taurorragus oryx), four kudu (Tmgelaphus srrepsi- terns), rwo gemsbok (Oryx ~dla),six springbok (Antidarcas I INTRODUCTION mnrsupiulis) and 33 domestic goats were drenched by stomach tube with extracts of the poisonous plant gifblaar (Dichapetalurn cyrno- mm) (Hooker) Engler and PrantI (=D, wnenabm Englm and Gilg). One of the most potent known poisons, monofluoro- Semi-quantitative analyses of the monofluoroacetate (MFA) content acetate (=sodium fluoroacetate) (MFA). which causes of the leaves were conducted at regular intervals and the proven blockage of the Krebs cycle and cardiac arrest in rumi- lethal (ca. LDm) ccprine dose was found to be equivalent to E.01- nants, found in the plant gifblaar (Dichaptalum 1,60 mg/kg MFA. Eland and kudu only succumbed at high dosage is levels of 6-8 mg/kg MFA and proved to be much less susceptible to cymosum) (Hooker) Engler and Prantl (=Drnvenemhtm gihlaar poisoning than goats. Springbok and gemsbok were as Engler and Gilg) (Steyn, 1928; Marais, 1944; Steyn, susceptible as goats, although confirmation is needed in gemsbok to 1949). Gifblaar occurs in large areas of southern Africa eliminate possible interaction between the immobilising drugs used including the north-eastern part of South West Af- and MFA. During separate voluntary inlake trials, eland ate limitad offerings of both low and highly toxic stages of giblaar. At these ricdNamibia (Map 1). Because it causes heavy annual dosages they showed no ill effects. Kudu on the other hand were mortality in domestic stock', gifblaar was selected for the more cautious and intake was minimal. first series of experiments, to determine the susceptibility The lesions caused by gifblaar are described. A few macroscopic of antelope to indigenous toxic plants. lesions observed in some of the animals have not knrccorded previously. These include: oedema and haemorrhages of the gall The investigation was conducted in the Grootfontein bladder with occasional blood-stained bile: oedema of the district of South West Africa/Namibia and consisted of sbornasum, periportal area of the liver, pancreas and pulmonary two separate studies. The first experiment was to detex- valves; adrenal haemorrhages and petechiae in the urinary bladder. mine the voluntary intake of gifblaas leaves while the se- Histopathological changes were describml in various organs such as the rnyocardium where replacement fibrosis became evident in cond experiment comprised toxicity trials where the animals which survived for two or mwe days. animals were dosed with an extract of the plant material, 2 EXPERIMENT l: (44%) and December (60-70% depending on the age of VOLUNTARY JNTARE the leaves). The dried leaves were thoroughly ground in a laboratory 2.1 Procedure hammemill at Ondersttpoort (0,5 mm mesh) and suspended in water. Guinea pigs (ca. six weeks of age) For more than a year, sublethal doses of specific quan- which were starved and withheld from water for 24 tities of counted leaves of gifblaar were periodically of- hours were dosed with this suspension by means of a fered to a varying number of eland (Taurorragus oryx), dosing catheter. Food and water were given ad lib after- kudu (Tragelaphus strepsiceros), springbok (Anri- wards. The 24 hours and 48 hours LD50of gifblaar far dorcas marsupialis) and cattle. AI1 these anirnaIs were each batch was determined using the method of Litch- starved and water was withheld for 24 hours before ex- field and Wilcoxon (1948). The LDS*of the sodium salt posure. The number of animals that ingested gifblaar as of MFA (sodium fluoroacetate 9896, Purum Fluka AG) well as the number of leaves ingested within 1-3 hours fon guinea pigs was determined in the same way and was determined. The intake was correlated with the found to be 0,5 (0,404-0,621 mg/kg. MFA content at the time (Table 1). The % MFA in the dried leaves was calculated from During the determination of voluntary intake, a sample these findings (Table 1). ConsequentIy, by considering of each batch of leaves was dried and submitted to On- the loss of moisture determined previousIy, the approx- derstepoort for MFA assay. The moisture content lost imate MFA content for each batch of green [eaves could by the process of drying was determined during May be calculated. FIGURE 1: The distribution of giblaar (Dichapetalum cymosum (Hooker) Engler &r. Psantl (National Herbarium. Pretoria. and SWA/Narnibia Herbarium, Windhoek, Nova 1980). Each dot represents a confirmed locality. 2.2 Results TABLE 1: MFA assays of dried gifbiaar Contrary to previous findings (Norval and Basson, 1974) tame eland frequently ingested varying quantities of gifblaar leaves (0-80) of both low and high toxic con- tent. Some individuals seemed to be more cautious and either avoided gimlaar completely or only ingested a small number of leaves. The findings were the same for cattle and sheep but kudu were much more wary and their intake of gifblaar was both exceptional and limited. There was no correlation between intake and MFA con- tent of the plant. 3 EXPERIMENT 2: TOXICITY TRIALS *Some of the extracts were prepared From these batches (as 3.1 General procedure indicated) Extracts from the leaves of D. cymosurn were prepared for suspension and extraction. Blending was done in a as follows. Plants were collected during September- Waring Blender and the suspension was left for ca. 12 October, which according to Steyn (1928) is the most hours overnight in closed containers at room toxic period d the plant. After defoliation, the mid-veins tcrnperature before being used for dosing. The suspen- of the older and coarser leaves were usually removed sion was strained through gauze or hessian to facilitate and discarded. The mass of the leaves was determined dosing by stomach tube with an automatic Phillips "Vis- on a triple beam balance. A suspension was either a-matic" drencher or a vacuum pump. Details about the prepared within 2-3 hours or the leaves were stored at processing are contained in Table 2. The MFA content 4OC and a suspension prepared a few days later. was assayed in extracts D1, D2, E and G 1-3 (Tables 1 and 2). Ten eland, four kudu, two gemsbok (Oryx gazel- As the toxicity varied considerably from week to week, la), six springbok and 33 domcstic goats were used as the extracts are dealt with separately (Table 2, A-E). experimental animals. All of them. except the eland, Consequently the results or the dosing trials with the came from areas where gifblaar does not occur. The in- various extracts should be compared separately rather dividual animals were dosed with the watery extract than jointly (Table 6). A similar suspension was (Table 2) to determine their susceptibility to gifblaar. As prepared from old leaves collected from less toxic plants the assays at Onderstepoort could only be conducted during May [Table 2, extracts F and G). Samples of after completion of the dosing trials, the degree of tox- these leaves were dried in the shade at room temperature icity of gifblaar and ca. LDloo for goats had to be deter- for 24 hours (extract G2) and eight days (extract G3) mined by dosing them with the various extracts. before the extracts were prepared. Moisture loss was 33% and 44,16% respectively. Immediately before dosing the mass of each animal was determined, either with a portable cattle scale or a large Since the active principle, MFA, is water soluble spring balance. Except for the first eland and some (Marais, 19441, cold tap water was used as a medium springbok, the animals were starved for 24 hours before TABLE 2: Watery extracts of D, cymosum: prmedure Extract A1 A2 B1 B2 C 131 I)z E F G1 G2 G3 P--------- -- 1974 1974 1974 1974 1974 1976 1976 1977 1975 1975 1975 1975 Date collected 14/10 14/t0 25/9 25,2719 25,27/9 8/9 13/9 6/9 5/5 12/5 12/5 12J5 Date blended 14/10 15/10 25/9 30/9 2/10