MAWQUA. VOL. 13. NO. l. I982ISg-70) 59 Antelope and poisonous S: CONTENTS 1 Introduction ...... 59 1. Gifblaar 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 ...... 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/ 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 (=) (MFA). which causes of the 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 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 . 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 . 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 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 8/9 13f9 6/9 5J5 12/5 13/5 2615 Extraction time (h) 12-14 12 13 15 13 12 12 12 12 12 12 12 Mass of kavcs (g) 505 1334 314 2027 480 4244 1360 3815,s 558 1555.7 247* 804* Massof mid-veins removed (g) 20 - 61,5 27 - Ralance of leaves (g) 485 1334 304 1965,5 453 4244 1360 3815,s 558 1355,7 247 804 Water added (ml) 5200 13150 ZOO0 12666 2500 25429 8160 22893 5250 10840 2100 7000 Res~due(after straining) (g) 388,s 1173 294,5 1508 36Q 3600 1208 3575 530 1401 419.5 1683 Balance of extract (ml) 4680 12950 1890 11325 2066 23435 8080 20000 ND ND ND ND Concentration of extract (m1 extract& of leaves) 9,65 9,7 6,2 5,76 4,56 S,5 5,94 54 t9,Q +8,0 +6,5 28-7 % MFA in dried leaves ND ND ND ND ND 03 0,29 0,2 ND 0,05 0,05 0.05 ND =Not determined * = Dried material they were weighed and drenched. The majority or TABLE 3: Gifblaar experiment: September-October: Eoats anteIope was caught in a crush without the aid of chemical agents, but where indicated, some animals were immobilised with a combination of etorphine HC 1 (MP9, Reckitt) and a neuroleptic, using a pneumatic Palmer Cap-Chur gun (Tables 7 and 8). The antidote, cyprenorphine (M285, Reckitt) was given soon after dosing to prevent possible interaction between etorphine and MFA. After drenching, animals had access to food and water, and were kept under close observation for 24-48 hours. Those animals which survived were observd for a further 12-14 days to determine the degree of recovery or the onset of latent effects. Autopsies were carried out wherever possible and organ specimens were collected in buffered 10% formdin from all the animals that had died. The tissues were prepared for histopathological studies in a routine manner. The sections of 3 to 5 p in thickness were stained with haematoxylin and eosin. Frozen sections of some livers, kidneys and mymardium were stained with oil red 0.

3.2 Goats

3.2.1 Dosing

h = Postdrenching priod in hours A total of 27 goats was drenched with various extracts * = Died after 33 days (Table 3, extracts A-E) prepared during Septemkr- October (spring) of 1974, 1976 and 1977. Dosages equivalent to 34g/kg of fresh leaves proved to be an which were calculated on the basis of fresh leaves, ca. LDIoo for goats during spring 1974, the toxicity of ranged from 0,5-4,O g/kg. During May 1975 (early same winter) another six goats were used (Table 5, extracts leaves during the period in 1976 increased so markedly that 1 g/kg proved to be lethal to goats (Table F-G). Dosage rates of fresh leaves (extracts F & GI) 6). It could have been even less, as lower dosages were and dried leaves (extracts G1 & Gj) in these animals not administered. ranged from 3-8 glkg, calculated on a wet basis.

TABLE 4: Gifblaar experiment: September-Octobr: antdope

Anw. ~wagc On& Death 3.2.2 Results 1% Exvact Sex (dB& syrnpmnsp) (h1 P---- Gernsbok The onset of symptoms in many of the goats dosed with OG 1 B2 F 3 5 10 the spring extracts of gifblaar was usually within 2 to 3 OG2 B2 M 4 4 10 hours. Initially they showed indolence and inappetence Springbok and preferred a ~e~~t'nbentposition. When aroused they AM 1 B2(1974) M 4 ? 20 AM2 C(1974) F 4 5 6 would walk a short distance onty to adopt the same AM3 C M 3 5 6 position once more. Shady areas were preferred. The AM 4 E(1977) F 4 ? 6 animals urinated frequently and appeared uneasy and Kudu depressed, TS 1 B2 M 3 ? TS2 Bz M 4 - - Their gait was often slow and ataxia was usually a very +S3 D2 F 4 54 ominous sign. Tachycardia and dyspnoea or polypnma TS4 D1 F 3 14 - with gasping were noted in the advanced stages. Eland Bleating of a moaning nature occurred frequently. Some TO1 A2 M 4 ? ataxic animals showed circling movements, excitement TO2 DI M 4 ?3 26 TO3 D1 M 3 73 - and terminal spasms. Lateral recumbency with spasms or galloping movements similar to heartwater were seen occasionally. Spells of excitement characterised by sud- den bewildered running, often into fences and bushes, TO 7 F and with fatal spasmodic collapse were noticed with the highly toxic material of 1976. Where an extract h = Post-drenching period in hours In those goats which received extracts of the May col- 3.3 Eland lection, the onset of clinical signs was delayed, rather uncertain and not as distinct as in the previous group. These animals originated from a known gifblaar area in For instance, two goats which received extract F (Table the southern Kavango. The eland which were yearlings 5) were mostly recumbent and unwilling to move. One and sub-adults, were in captivity for at least six months (dosage 8 g/kgj died 16 hours and the other (4 before commencement of the tdals. They had access to g/kgj 48 hours after dosing. natural browse and were fed lucerne hay and Rider cubes (Epol) twice daily. Rock salt and fresh water were Secondly, three goats which were given extract G,at available ad lib. dosages ranging from 3-5 g/kg, showed inappetence for a 3--4 hour period which commenced approximately 2 hours after dosing. Nothing more dramatic was noticed 3.3.1 Dosing until 30 hours when ode animal (dosage rate 5 g/kg) became recumbent and refused to eat. This goat bleated One two-year-old bulI (TO I) which was not starved in a moaning way and remained recumbent for almost previously, was immobilised (Table 7) and dosed by 40 hours. It eventually recovered. The other two goats stomach tube with the October extract (Az). Nine other also showed inappetence at 30 hours and developed eland were dosed during various seasons without the aid peculiar spells of excitement at 48 hours. Shaking move- of any immobilising agents. They were herded into a ments of the head, kicking at the flanks, sudden running crush after a starvation period of ca. 24 hours. Seven with sternal recumbency were repeatedly seen. How- eland (TO 2-8) received the highly toxic material (Table ever, both animals recovered. 4, extracts D and E) colIected during spring (1976 and 1977), whereas two eland (TO 9 and TO 10) were drenched with the May extracts (Table 5, G1and GJ). Thirdly, a goat which was dosed with extract G2 at 8 The details abut the procedures are given in Tables 4,5 g/kg showed anorexia and an inclination to sterna1 and 7. recumbency at 10 hours. Almost continuous bleating followed at 2 1 hours. The animal then adopted a lateral recumbent position in which it died at 32 hours. Gallop- 3.3.2 Results ing movements were seen at times before death. Because eland TO l was not starved beforehand, there TARLE 5: Gifblaar experiment: May was an increase in pressure on the diaphragm during

Equivalent Onsw Death drenching which was caused by the unusually large Extracl Sex dowg (dkg) symptoms (h) (h) volume of the extract on the full rumen of the recumbent Goat and immobilised animal. This produced such an adverse 28 F F 4 3-4 48 spasmodic reaction that cardiac arrest was feared. The 29 F F 8 3-4 16 soon - reaction was too fur the toxic agent to have had 30 G1 F 3 3-4.48 any effect, as a minimum interval after dosing of ap- 3 1 G1 F 4 3448 - 32 GI F 5 3-4.30 - proximately 2 hours is required for the appearance of 33 G2 F 8 10 32 symptoms and 5 hours for death to occur. This is in Springbok accordance with the known latent period required for AM 5 GI M 2,7 ? 17 MFA (Jensen, Tobiska and Ward, 1948; Robinson, AM 6 GI M 33 ? 27 1970; Vickcry and Vickery, 1973). Eland TO 9 G1 M 4 - - Following the administration of the antidote the animal TO 10 G3 F 8 - - rose and did not reveal any sign of intoxication until 5 hours later when the Follawing symptoms were noticed: h = Post-drenching period En hours Extracts G2 and G3 were prepared from dried leaves and the sternal recumbency, uneasiness, inappetence, salivation dosage calcuIated on a wet basis. with mouth slightly opened and occasional protrusion of the tongue. The symptoms disappeared within an hour and an uneventful recovery was made. Apart from differences in the clinical picture, the ca. The three eland drenched with the most toxic extract LDlm for goats was considerably higher (ca. 8 g/kg) ID1) did not show any serious symptoms. They were when the May extracts were used. It was important to found to be recumbent at times but rose whenever ap- consider these facton and establish the toxic levels of proached. Recumbency was always interruptd by the different extracts in goats in order to calcula~e periods of normal browsing. All of them appeared nor- dosage rates in the antelope and determine their suscep- mal, quite at ease and were found feeding the fotlawing tibility to gifblaar poisoning. day. However, one animal (TO 2) (dosage rate 4 g/kg) Finally, the MFA assays indicated that the ca. LDloo of died suddenly a few hours after this observation. MFA for goats was found to be equivalent to 1,Ol-1,60 Of four eland dosed with the E extract (Sept. 1977), mg/kg (Table 6). none showed any symptoms of gifblaar poisoning. The 64 emn.NORVAL HOPMEYR. EBEDE~,ScHuLTz

two eland (TO 9 and TO 10) which received the May D1 (Sept. 1976) at 4 and 3 g/kg respectively (Table 4). extract (4 and 8 g/kg respectively) did not develop any They were released in a small camp for observations. untoward effects.

Based on the MEA assays, at least 6-8 mgJkg MFA 3.4.2 Results was required to kki one of two eland (Table 6). The youngest kudu bull (TS 2) which received 4 g/kg did not show any signs of poisoning at any stage after dosing. His appetite was unaffected and both food and 3.4 Kudu water were taken within a few minutes after the ad- ministration of the antidote against the immobilising The kudu were caught in the south-western Otjo- agent. However, kudu TS 1 (dosage rate 3 g/kg) was in- vasandu area of the Etosha National Park. They were clined to recumbency, but rose whenever disturbed or accommodated for 38 days before the studies com- appraached and appeared normal otherwise. It showed menced. Their natural diet was substituted twice daily no interest in food or water. The next morning both with lucerne hay and Rider cubes and they had free ac- kudu were reIeased into a small camp where food and cess to water. water were taken normally. No other symptoms developed. The two kudu cows (TS 3 and TS 4) were apparently af-' 3.4.1 Dosing fected 3 hours after dosing. Both animals were inclined to sterna1 recumbency and, although intervals of brows- Two young kudu bulls (TS 1 and TS 2) were im- ing did occur in the late afternoon, they were more fre- mobilised 40 hours after starvation and drenched by quently seen in a recumbent position than the four eland stomach tube with gifblaar extract BZ (dosage rate 3 and which were dosed on the same day. The folowing day 4 g/kg respectively) (Tables 4 and 8). For close observa- (2 1 hours post-drenching) both cows were recumbent, tion they were retained in a wooden pen for 24 hours more listless and oppressed. Shivering and stretching of and provided with water and their usual ration, They the neck occurred in both animals. TS 3 (4 g/kg leaves were subsequently released in a small camp for further or 6-8 mdkg MFA) (Table 6) died approximately 24 observation for another 12 days. Two adult cows (TS 3 hours after dosing. TS 4 (3 dkg) remained recumbent and TS 4) were caught in a crush without the aid of any the whole day and appeared to be oppressed. However, immobilisation and dosed with the highly toxic extract she recovered uneventfully on the third day.

TABLE 6: Seasonal comparison of dasing trials

The ratios (fifth column) e.g. 1/2 represent the rnortdities (left) out of total number dosed (right). Some goats received the D2 Ekbact (03%MFA), but the antelope DIEaract (0,5% MEA). ANTELOPE AND POISONOUS PLANTS 65

TABLE 7: Details about the dosing programme, of cland No. TO1 TO2 TO3 TO4 TO5 TO6 TO7 TO8 TO9 TO10 Date Oct. 74 Sept. 76 Sept. 76 Sept. 76 Sept. 77 Sept. 77 Sept. 77 Sept 77 May 75 May 75 Sex M M M M F E M F M F Approx. age (years) 2 + 1 k 1 + 1 2 2 2 2 1,5 1,5 Mass of animal (kg) 170 136 116 129 I80 220 175 167 145 180 Dosage: Leaves (&/kg) 4 4 3 4 4 3 3 2 4 R Total dose (m]) 6596 3003 1921 2848 3887 3563 2835 I803 4000 h100 Extract dosed A2 DE DI D1 E E E E GI, G3 tmmobilising agents (mg): M99' (e~orphine hydrochloride) 4 - - - AZaperone2 100 - I - Immobilisation time (min./s.) 1210 ------*Interval (min.) 38 ------Antidote: M2RSt (cyprenorphine) (mg) 12 ------Recovery time (min./s.) NI) ------Starvation (h) - 24 24 24 24 24 24 24 24 24 Water withheld (h) 24 24 24 24 24 24 24 24 24

*Interva!*= time between dosing and administration uf antidote NI3 = not determined IReckitt "anssen Pharm.

TABLE S: Details about dosing programme of antelope

Kudu springbok

No. TS1 TS2 TS3 TS4 OG1 OG2 AM1 AM2 AM3 AM4 AM5 AM6 Date Sept.74 Sept.74 Sept.76 Sept7h Sept.74 Sept.74 Sept.74 Sept.74 Sept.74 Sept. 77 May 75 May 75 Sex M M F P F M M M M E M M Approx. age (years) 1,5 0,6 Adult Adult 1 I 2 I I &2 +3 k3 Mass of animal (kg) 153 78 146 144 68 88 33 25 25 25 393 36 Dosage (&g) 3 4 4 3 4 3 4 4 3 4 3 4 Total dose (ml) 2639 1794 3224 2385 1564 1518 759 342 456 540 74Q 1000 Extrsct dosed BI B2 D1 DI Bz B2 B2 C C E GI G) Immobilising agents (mg): M99l letorphine nydrochloride) 4 2 2 2 1,5 1,5 1.5 - 2 2 Azaperonel I - - - - - 100 100 Acetylpromazine' 10 S - - 10 10 I- - - - Hyoscinc hydrobromide' - - - - 10 L0 - - - Sernylan5 (phen- cyclldine hvdrochloride) 60 30 - 50 50 - - - Serenace6 (haloperidol) _ I_ - - - - ' 1 2.5 ' 2.5 ' - - - Rompum' (xylazine) ------15 - Irnrnobilisatian t~me I (rnin./s.) 7/5 13/40 - - 5/36 4/22 5/40 10/47 2/45 - ND ND *Interval (min.) - - - - 15 - - - - Antidote: M285 (cyprenorphine) (mg) 12 6 - - 6 6 5 S 5 4 4 Recovery time (min./s.) 0/58 2/0 - - 1/25 1/40 4/45 O/JS 2/45 - ND ND Starvation (h) 40 40 24 24 41 4 1 - - - 24 24 24 Water withheld (h) 12 12 24 24 113 13 - - - 24 24 24

*Interval = time between dosing and administration of antidote + = drug given folIowing morning ND = not determined ' Reckitt lJanssen Pharm. 'Boots Pure Drug Co. 'Burroughs t Wcllcome Co. Parke-Davis Searle 'Bayer 3.6.2 Results

These animals were captured at the same time and in the AM l showed inco-ordination for at least 15 minutes same area as the kudu. They were Fed Rider cubes and after revival, but this was evidently due to the effect of hay treated with Morea 30 (30% urea in an ethyl the xytazine. No further ill effects were noticeable until alcohol molasses complex) and Moranol (van Borsen) the animal was found dead after 20 hours. Both AM 2 which is an alcohol-molasses compound. Nine Iitres of and AM 3 developed sudden severe intermittent convul- the former and 18 litres of the latter, diluted in 180 litres sions with bleating 5 hours after dosing. The former died of water were sprayed over the hay. within 15 minutes and the latter within half an hour after the onset of symptoms (Table 6). AM 4 was found dead 6 hours after dosing. No symp- 3.5.1 Dosing toms were noticed beforehand. The remaining two springbok (AM 5 and AM 6) recovered within a minute Two gemsbok, one male (OG 2) and one female (OG l), or two after the administration of the antidote, but both were immobilised with a combination of etorphine, revealed drowsiness and ataxia until death intervened 17 acetylpromazine (Boots), and hyoscine (Burroughs hours and 27 hours respectively after dosing (Table 6). Wellcome) (Table 8), drenched with 3 and 4 gJkg It was evident that the animals became affected by the respectively of extract l32 and then rcvivd. gi(bIaar extract while still under the influence of azapesone. Peak effects of azaperone are known to last for 2 hours with a rapid decline between the second and eighth hours (Marsboom, 1969). However, the 3.5.2 Results azaperone dose recommended by Pienaar (1 973) for the immobilisation of springbok is considered excessively Both animals were inclined to lie down; OG 2 within 4 high, hence the prolonged drowsiness and ataxia which hours and OG 1 within 5 hours. They were drowsy and set in. OG 1 (dosage 4 g/kg) showed muscular tremors. Both became progressively worse and at 9 hours, OG I 3.7 Pathology showed severe ataxia when aroused. It died 15 hours later. At this stage severe imbalance was also evident in Most of the cases were acute, some sub-acute and only OG 2, but at 10 hours it was standing calmly in the pen one goat died 33 days after dosing. when it died within minutes after a sudden fatal seizure (Table 6).

3.7.1 Antelope

No macroscopic observations could be made in the one 3.6 Springbok kudu and one eland that had died. Specimens were, however, collected by a stock inspector. All the other 3.6.1 Dosing animals were autopsied. Cyanosis and congestion were always present. The Three springbok (AM 1, AM 2, and AM 3) were cap- livers were usually congested, sometimes with petechiae tured by immobilisation. AM l which was immobilised or haemorrhages beneath Glisson's capsule (OG 2). with and xylazine (Rompun, Bayer), was drenched M94 Degeneration was suspected. The lungs were mildly with 4 g/kg of extract B2 within l hour after capture. congested with a few petechiae. Pulmonary oedema was Sixteen hours after capture AM 2 and AM 3 were tran- present in springboks AM 4, AM 5 and AM B. The quillised with 2,5 mg haloperidol (Serenace, GD. Searle heart was usually dilated, Myocardial degeneration, & Co.) (Hofmeyr, Luchtenstein and Mostert, 1 977) and mainly in the papillary muscles, was seen in gemsbok then dosed with 4 and 3 gJkg respectively of extract C OG 1, and springboks AM 2, AM 3 and AM 4. Mild (Table 8). In order to combat stress and other untoward subepi- and subendocardial petechiae were usually effects due to capture, all three springbok were treated noticeable but were never very prominent, except in AM prophylactically with a vitamin E-selenium preparation 6. Congestion OF the small intesrines, occasionally with (BO-Se C yanamidj and a long-acting antibiotic. mild enterorrhagia, was fairly commorr, but absent in Springbok AM 4 which had been in captivity for 10 OG 2 and AM 4. The kidneys were also congested and months was dosed with 4 g/kg of extract E, without be- mild nephrosis was suspected in the two gemsbok and ing chemically immobilised. Two other springbok (AM AM 4. Some animals (AM 2 and AM 3) revealed a Few 5 and AM 6) which had been captive for three years petechiae in the urinary bIadder and congestion and/or were immobilised with etorphine and azaperooe (Jans- haemorrhages of the adrends (OG 2 and AM 2). Mild sen Pharm.) (Table 8) and then dosed with 3 and 4 g/kg cerebral oedema was suspected in AM 3. AM 2, AM 3, of extract Cl, respectively. OG 1 and OG 2 revealed oedema of the gall bladder with some haemorrhages whilst AM 3 had a consider- filtrative and proliferative (fibroblastic) changes were able amount of blood in the bile contents. Abornasal noticeable in the necrotic foci. Congestion, some oedema was seen in both gernsbok and springbok AM 3 haemorrhages, especially in the auricles, and occasional and also oedema of the pulmonary valves, pancreas and oedema were sometimes present. In the skeletal muscles, perborfd area in gemsbok OG 2. Zenker's changes were seen in scattered individual fibres of a few animals.

3.7.2 Goats The divers were usudly moderately to severely wn- gested and oedematous with varying degrees of fatty As some specimens were collected by stock inspectors, degeneration, Whenever abundant proteinaceous the incidence of the lesions in the various animals can- material or even globules were present in dilated spaces not be given accurately. However. most of the lesions of Disse, this was regarded as oedema. The distribution were similar to those found in the antelope. Congestion, or the fatty changes varied, being either zonally (peri- degeneration and enlargement of the liver, with conges- pherally or centrilobular~y)or diffusely spread in the tion and suspected degeneration of the kidneys as well lobuli. Centrilobular necrosis accompanied by neutro- as pulmonary and inlestinal congestion were most fre- phi1 infiltration and peripheral fatty changes occurred in quently encountered. The mvocardiurn, either entirely or a t'ew animals, A restricted mne of necrosis and zonally (such as the endocardial region and papillary haemorrhage was occasionally seen around the gall muscles), often had a parboiled appearance. Mild sub- bladder. The latter was Frequently congested and endocardial and subepicardial haemorrhages were seen oedematous, sometimes with concomitant haemor- occasionally. Larger haemorrhages were noticeable in rhages and necrotic foci. A small to moderate number ol the wall of the right auricle of a few animals. Approx- large cosinophilic globules was found in the hepato- imately 50% of the goats revealed variable degrees of cytes in a third of the cases. congestion, oedema and even mild haemorrhages of the Congestion of the kidneys was present in most of the gall bladder. Lesions that were less frequently en- animals. With the exclusion of small number of countered included pulmonary oedema, enterorrhagia, a animals, nephrosis was a common feature. It varied abomasal oedema, very mild haemorrhages and from cloudy swelling, vacuolar or fatty degeneration to suspected oedema of the urinary bladder. frank necrosis. Hyalin globules were occasionally found The spleen was usuaily either small or of normal size but in the cytoplasm of the cortical cells. The capsular sometimes mildly enlarged. spaces of Bowman and many of the cortical tubuli, es- pecially the proximal convoluted tubuli, were frequently dilated and contained much proteinaceous material. 3.8 Histopathology Eosinophilic globules were often seen in the capsular spaces. Reflux of tubular epitheIiurn in these spaces was Two gemsbok, one eland, one kudu, six springbok and present in one goat. Necrosis was usually seen in the dis- 23 goats were examined. The most important lesions, tal convoluted tubuli, ascending hpof Henle, spiral although not constant, were present in both the antelope tubuli and outer medullary area; but occasionally other and goats. For this reason the histopathological findings tubuli and the glomeruli were also affected. of both groups are dealt with simultaneously. Further- more, as there appeared to be no correlation between the The brains of some animals were either congested, mild- dosage rate, or survival time and severity of the lesions, ly swollen andJor oedematous. A very mild or mild except in the myocardium, the animals are not dealt status spongiosus of the white substance occurred in a with individually. few of the goats and antelope. The spongiosity was un- related to any specific dosage level or any length of sur- lrt the heart the papillary muscles and the subendo- vival period. Mild gliai swelling was present in a f~ cardial zone of the left ventricle were most consistently animals. affected. Other areas including the inner and outer walls of both ventricles and the apex were also frequently in- The spleen was either congested or somewhat con- volved. Although not always very obvious, degeneration tracted and about 30% showed variable degrees of OF the myocardium was a constant feature. The most kariorrhexis of the sptenic corpuscles. This was some- common findings were swelling of the fibres, hydropic times also noticeable in the lymph nod~s,which were un- rareiaction and mild fatty changes, frequently accom- fortunately not regularly studied. Oedematous lymph panied by foci or patches of more advanced lesions, es- nodes were encountered occasionally. pecially in the papillary muscles. The latter changes Apart from occasional abomasal oedema, congestion were characterised by zonal rarefaction and irregular and haemorrhages were more hequent in the small in- narrow intermittent eosinophilic bands. The most ad- testine. These changes were at times accompanied by vanced lesions were overt Zenker's necrosis. Mineralisa- necrosis of the tips of the vilIi. tion was present in two animals that died at 21-24 hours. In those animals that survived for approximately Some of the urinary bladders showed very mild congea- two days or more, macrophage mobilisation, mild in- tion, haemorrhages and occasionally mild oedema. The lungs were congested and about 30% revealed where assays were made (Table 6). The ca. LDlm of oedema. Pneumonitis and acute thrombosis of some goats killed gemsbok and springbok but in no instances vessels were present in one goat with a survival pcriod of eland or kudu. During 1936 the lowest dosage rate of 32 hours (dosage rate 8 g/kg of extract Gz) (Table 5). 1,01 mg/kg MFA used proved to be an approximate The adrenals were sometimes congested and a Few con- LDloo for goats, but a five-fold increase (5,25 rng tained intracytoplasrnic eosinophilic globules in various MFA/kg) failed to kill eland and kudu. This only hap- pened at dosage level of 6 to 8 mg MFAIkg which zones such as the zoaa fasciculata, zona glomemlosa, a zona reEicuiaris and in exceptional cases even in the constitutes at least a seven-fold increase of the caprine medulla. Specimens of the pancreas were collected from LDloo. Considering all the evidence. it can be safely a few animals, and in two of these, congestion, haernor- stated that eland and kudu need a six- to seven-fold in- rhages and focal necrosis were observed. The latter was qease of the ca. LDmo of MFA for goats to produce macroscopically noticeable as greenish areas. Micro- some mortalities. It is evident therefore that both kudu scopically they represented necrotic foci around affected and eland are much more resistant to gifblaar poisoning than goats. (1957) pancreatic ducts some of which contained numerous Garner gives the oral lethal dose of bacilli. The greenish cotour is thought to be due to bile MFA for goats as 0,3-0,7 mg/kg (Table 9). According seepage or regurgitation of bile. to Robinson (19701, the LDso for cattle is 0,247-0,625 mg/kg. Thesc findings and our own investigation show Springbok AM 4 revealed no significant degenerative le- that cattle are equally or even slightly more susceptible sions in either myocardium or parenchymatous organs to gifblaar poisoning than goats. such as the liver and kidneys. Similarly, in a few goats Only one and degeneration was so mild that it could easily have been of the ten eland two of the four kudu overlooked. which were drenched were chemically immobilised. Consequently the advisability of such immobilisation in TABLE 9: Oral lethal dose of MFA in mglkg body weight of various gernsbok and springbok comes into question. As the animals (Garner. 19571. combination of immobilising agents varied, an adverse and possible synergistic efEect between some of the drug Horse ...... 0,SQ-1,75 combinations and MFA cannot be ignored entirely. Sheep ...... 0,25-0.50 Drugs in question include xylazine used in one spring- Goat ...... 0,30-0.70 bok, the high dose of azaperone used in two springbok Pig ...... 0.30-0.40 and both Dog ...... 0,06--0,20 in particular hyoscine which was used in gems- Cat ...... 0,30-0,50 bok. Hyoscine is a powerful cholinolytic agent and Fowl ...... 10,0&30,00 produces inter alia tachycardia which in the gemsbok may well have enhanced the toxic effect of MFA on the myocardium. It would therefore be advisable to repeat dosing trials on gernsbok preferably without using im- mobilising compounds or at least by omitting hyoscine. 4 DISCUSSION AND CONCLUSIONS Springbok AM l had fully recovered overnight from the effect of xylazine before it died the next afternoon, but The trials on voluntary intake have shown that certain the high dose of asaperone used in AM 5 and AM 6 ob- antelopc will eat gifblaar at least under some adverse cir- viously caused the animals to remain drowsy and ataxic cumstances such as starvation but that kudu are ap- after MEA had taken effect. However, the death aT AM parently much more wary than eland and springbok. It 4 a Few hours after dosing it without the use of chemical should, however. be taken into consideration that the immobilisation is substantial evidence that springbok animals had in captivity for a prolonged period and been are at least as susceptible as goats and that the im- that the regular feeding by man could have played a role mobilising agents played a negligible or no role at all in in their acceptance of the plant. enhancing death in these antelope. MFA assays confirmed that the most toxic stage of gif- blaar is during spring (September) and another high All the antelope except the first three springbok were peak is reached during late summer - early autumn given adequate time for adaptation in captivity, before (March) (Steyn, 1928; Vickery and Vickery, 1973;Tm- commencement of the trials. The shortest period was nock, 1975). five weeks in two kudu and two gemsbok and it ex- ceeded six months in all the other animals. Apart from The assays also indicate that the toxicity may vary from handling and dosing, any stress which could have year to year and that a drastic variation may occur even precipitated capture myopathy and enhance death dur- within seven days of collecting the material. The lowest ing the trials can therefore be regarded as negligible. level of 0,0143% MFA compared with the highest level of 0,5% MFA represents a 35-fold increase. Due to this Some of the macroscopic lesions observed have not variation in toxicity and the fact that MFA assays were been recorded previously for gifblaar poisoning (Steyn, not done regularly, an evaluation and comparison be- 1928; and Steyn, 1949). These lesions include oedema tween goats and antelope are only valid within each and haemorrhages of the gall bladder with occasional separate trial and not collectively or between those trials blood-stained bile, oedema elsewhere such as the abomasum, per-portal area, pancreas and pulmonary Mr B. de la Bat, former Director and Mr P. Swart, valves, and adrenal haemorrhages and petechiae in the Acting Director of Nature Conservation, Swth West urinary bladder. It is also noteworthy that the intestinal Africa/Namibia, for the provision of game from Etosha congestion described by Steyn (I 928) and Steyn (1949) National Park. was frequently present, whereas enterorrhagia in the Dr T, W. Naudl, toxicologist and Deputy Director at small intestines was found in a small percentage or the Veterinary Research Institute, Onderstepoort, for his animals. valuable advice and assistance. Mild fatty changes proved to be a fairly common lesion Dr J. G. Pienaar, Head of the Section Pathology at the in the myocardium and liver. It is sometimes preceded Veterinary Research Institute, Onderstepoort, and his or repEaced by hydropic changes or cloudy swelling. staff for the preparation of the histopathological sec- More advanced lesions include hyalin droplet degencra- tions. tion (Iiver) and necrosis in both liver and rnyocardium. Replacement fibrosis in the latter is noteworthy in Mr H. F. du Plessis, a game rancher from the farm animals which survived for two or more days and is Shunem, Grootfontein, and his assistants who caught reminiscent of the lesions in Gmrgina River Poisoning several of the eland on horseback. caused by MFA in Acacia georginoe (Whittern and The staff of the Etosha National Park and especially Mr Murray, 1963). Other changes that need emphasis are Manie GrobIer for their co-operation and assistance. kariorrhexis of the splenic corpuscles and lymph nodes, The late Mr C. Kriigel, Mtssrs J. Oosthuizen, J. Alberts, oedema of the liver and the mild status spongiosus of the J. Geldenhuys and J. Brits, stock-inspectors at Groot- brain in some cases. fontein, for assistance. It is accepted that some of the lesions encountered, notably tubular reflux and accumulation of eosinophilic globules in the renal capsular spaces, could have been caused by shock. Gifblaar poisoning is of considerable economic import- ance. Although there are apparently no figures avail- 6 REFERENCES able on the annual losses of domestic stock caused by gifblaar in southern Africa, an estimate for the Groot- GARNER, R. J. fontein district alone would be at least 300 cattle a year. 1957 : Veterinary Toxicology. Bailliire Tindall & Cox It is undoubtedly the most' important cause OF death HOFMEYR, J. M,, LUCHTENSTEIN, H. G. and amongst livestock in this area. Reports of mortalities in MOSTERT, P. K. N. wild antelope are also lacking. However, the relatively 1977: Capture. handling and transport of springbok and the high resistance of eland and kudu to gifblaar poisoning application of haloperidol as a long-acting neuroleptic. Madoqlia 10:123- 130. which became evident during the present studies, tempts JENSEN. R., TOBISKA, J. W, and WARD. J. C. one to emphasise the potential of selective game 1948: Sodium fluoroacetate (compound l080) poisoning in ranching in gifblaar areas and possibly also other areas sheep. Am. J. vet. Res. 9370-372. where poisonous plants abound. It is also interesting to LtTCHFIELD, J. T. and WILCOXON, F. note that gifblaar areas generally fall within the natural 1448: A simplified methcd of evaluating dose-effect ex&- habitat of eland and kudu, whereas the major natural ments. J. Plrarmac. exp. Ther. 96(2>:99-133. habitat OF springbok and gemsbok occurs elsewhere. MARAIS, J. S. C. 1944: Monofluoroacetic acid, the toxic principle of "giiblaar", Atthough small numbers of gemsbok are occasionally Dtchopeiab~mc,vn?osum (Hook) Engl. Onderslepoorr J. found in the gifbjaar areas of South West Africa1 20(1):67-73. Namibia, they are known grazers, and were consequent- MARSBOOM, R. ly not exposed to MFA during their evolutionary 1969: On the pharmacology 6f azaperone, a ncumleptic used development. for the restraint af wild animals. Acra Zoo1 plh, kntv. no. 48:lSS-161. NORVAL, A. G. and BASSON, P. A. 1974: Eland avoid g~fblaar.J.S. Afr. ver. med Ass. 45:233. PIENAAR, U. de V. 5 ACKNOWLEDGEMENTS 1973: The drug immobilization of antelope specics. In E. Young (cd.) The caplure and care of wild animals. Gape We are indebted to the following: Town: Human & Rousseau. ROBINSON, W.D. The late Deputy Director, Dr T. Veenstra, the previous 1910: Acute toxicity of sodium rnonofluoroacetate to cattle. I. Deputy Director, Dr C. van N. Jonker, and the present Wildl. Mgmr. 34547-648. Director, Dr H. H. P. A. Schneider of Veterinary Ser- STEYN, D. G. vices Windhoek, for their permission and support to 1928: Gifblaar poisoning. A summary of our present OF conduct the project. knowledge in respect poisoning by DichupetaIum cyrnosurn. 13th and 14rh Rep. Dir. Vet. Ed. arrd Res. The Kavango Government for permission to obtain 1:185-194. antelope in the Mangetti area. 1949: Vergfliging van mens en dier. Pretoria: J. L., van Schaik. 70 BASSON, NORVAL, HOFMEYR, EBWES, SCHUtTZ

TANNOCK, I. WHI'lTEM, J, H. and MURRAY, L. R. 1975: Seasonal variation in toxicity of Dichnpetalum cymosum 1963: The chemistry and pathology of Georgina River poison- (Hook) Engl, in the Nyamandhlovu area. Rhod. J. Agric. ing. AUSI.ve!. J. 39:168-173. Res. 13:67-70. VICKERY, B, and VICKERY, M. L. 1973: Toxicity for livestock of organofluorine compounds pre- sent in Dichapetaium plant spies. The Veterinary Bu1- Ierin 43537-542.