Kalanchoe Lanceolata Poisoning in Brahman Cattle in Zimbabwe: the First Field Outbreak
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Case report — Gevalverslag Kalanchoe lanceolata poisoning in Brahman cattle in Zimbabwe: the first field outbreak Cecilia Masvingwea and M Mavenyengwab FIELD INVESTIGATION ABSTRACT A farm visit was undertaken to investi- Field outbreaks of Kalanchoe lanceolata poisoning in cattle on a commercial farm in Zimbabwe gate possible toxic causes for this condi- are reported. The clinical signs and pathological lesions observed in field cases resembled tion, during which a necropsy was those reproduced in an experimental cow and were consistent with acute cardiac glycoside performed on a cow reported to have died poisoning. after showing signs similar to those Key words: acute cardiotoxicity, cattle, Kalanchoe lanceolata, poisoning. described above. Grossly, an ulcerative Masvingwe C, Mavenyengwa M Kalanchoe lanceolata poisoning of Brahman cattle in haemorrhagic gastroenteritis, hydroperi- Zimbabwe: the first field outbreak. Journal of the South African Veterinary Association (1997) cardium with fibrin strands, petechiation 68(1): 18–20 (En.). Department of Preclinical Veterinary Studies, Faculty of Veterinary of the epicardium and moderately dark Science, University of Zimbabwe, PO Box MP167, Mt Pleasant, Harare, Zimbabwe. discolouration of the myocardium were observed. After due consideration, plant intoxications causing diarrhoea and gastroenteritis were regarded as the most INTRODUCTION 140 km west of Harare. These outbreaks probable diagnosis. Samples of the brain, Kalanchoe lanceolata is an erect, usually were observed during the rainy seasons of kidney, heart, liver, intestines and skeletal unbranched annual and occasionally 1991/92, 1992/93 and 1993/94. The affected muscles were collected and preserved in perennial succulent plant standing about herd was grazed separately on an exten- 10 % buffered formalin for histopatho- 1 m in height4. On the farm near Chegutu ded rotation system utilising two large logical evaluation. Histopathological (about 140 km west of Harare) where the undivided paddocks of a partly-cleared lesions were similar to those previously outbreak occurred, it stood about 40 cm at woodland. Investigations during the noted. flowering. The flowers are star-shaped 1991/92 and 1992/93 outbreaks, when an The paddocks were surveyed for and the four corolla lobes a mixture of unspecified number of animals died, were poisonous plants. Specimens of known apricot and yellow. The inflorescences are inconclusive. At that stage the animals poisonous and unknown plants were borne on the axils of upper leaves. Of the presented with diarrhoea, excessive collected for positive identification by the family Crassulaceae, the genera Kalanchoe, voiding of urine, a pounding, rapid heart National Herbarium, Harare. Amongst Cotyledon and Tylecodon contain bufa- beat, muscle tremors and frothing. In the the plant species collected were the poi- dienolides that are capable of causing terminal stages, affected animals would sonous Pavetta schumanniana, Acacia sieber- acute cardiac toxicity and a chronic paretic isolate themselves, charge at attendants, ana, Solanum delagoense and Kalanchoe syndrome1–3, depending on dose and tire easily, collapse and die. Death lanceolata. duration4. occurred within 24–48 h of onset of clinical A second visit to the farm was under- The distribution of K. lanceolata in signs. At necropsy no significant patho- taken to verify the population densities of Zimbabwe has not been reported fully logical lesions were detected but the the poisonous plants identified and to but the plant has been recorded from investigators noted remission of clinical establish whether any of these plants had highveld areas such as Chegutu, Zvimba, signs and deaths after the relocation of been grazed. A survey of the 2 paddocks Mazowe and Mayo. It is known to grow animals to a different paddock. revealed abundant K. lanceolata with evi- in the shade of trees and bushes and often During the 1993/94 outbreak, which we dence that it had been grazed. A sack was forms dense stands4. On the affected farm investigated, 22 animals were affected filled with the plant for feeding trials. it grew densely on richer soils, for exam- over a period of 2 months. Clinical signs ple on anthills, and was associated with were similar to those described above. FEEDING TRIAL fields of overgrazed Cynodon dactylon. About half of them died or were destroyed Mazowe Field Station, a government during the aggressive phase. The remain- veterinary research farm 30 km north of HISTORY OF OUTBREAKS der seemed to respond to oral gavage, by Harare, was used for the feeding trial. Mortalities from an unknown cause the referring veterinarian, with 10 l of There was no history of similar outbreaks occurred in a Brahman breeding herd on cow’s milk per animal. on this farm and Kalanchoe lanceolata was a commercial farm near Chegutu about Necropsies performed on 3 animals that not present. Initially, a Brahman cow was died during the 1993/94 outbreak revealed selected for the trial. She proved too a mucoid to haemorrhagic gastroenteritis, aggressive to be handled and a 5-year-old aDepartment of Preclinical Veterinary Studies, Faculty of brain oedema and petechiation of the epi- Friesian cow, weighing about 450 kg, was Veterinary Science, University of Zimbabwe, PO Box MP cardium. Histopathological examination then used. The cow was starved for half a 167, Mount Pleasant, Harare. showed scattered areas of fine granular day but had access to water. It was then b Central Veterinary Laboratory, Harare. degeneration of myofibres and a haemor- hand-fed 7 kg of K. lanceolata (stems and Received: March 1996. Accepted: January 1997. rhagic gastroenteritis. leaves) over 2 hours, and thereafter 18 0038-2809 Tydskr.S.Afr.vet.Ver. (1997) 68(1): 18–20 allowed to graze with the rest of the herd and monitored twice a day for signs of illness. Clinical signs were observed from 2 days post-ingestion and included isola- tion from the rest of the herd, tachycardia, weakness, diarrhoea and frothing at the mouth. All these signs, with the exception of frothing, persisted until death. The animal died in sternal recumbency, with a backward extension of hind legs, 2 weeks post-ingestion (Fig. 1). A necropsy was performed on the farm. Gross examination revealed epicardial haemorrhages and myocardial conges- tion. A muco-haemorrhagic enteritis with paintbrush mucosal haemorrhages, abomasal hyperaemia and scattered abomasal ulcers about 5 mm in diameter were also noted. The abomasal and rumi- nal contents were voluminous and fluid. Tissue samples of the heart, liver, kidneys, brain, skeletal muscles, lungs and intes- tines were collected and fixed in 10 % buffered formalin for histopathological examination. Fig. 1: Experimental animal in sternal recumbency with backward extension of the hind The heart microscopically showed legs. myofibre oedema and degeneration indicated by granularity, swelling and vacuolation, and interfibre oedema evi- denced by widening of interfibre spaces (Fig. 2). Hyperaemia and haemorrhage in the myocardium were also present. Con- gestion and scattered haemorrhages were noted in the mucosa and submucosa of the intestines. DISCUSSION The clinical signs and pathological lesions from field cases appeared similar to those observed in the feeding trial and conform to those described by other workers5,7,8. Aggression, as observed in field cases, was only directed towards attendants and not towards objects or other animals as would have been ex- pected in a true neurological syndrome. It is possible that this could have been a breed-related stress response of Brahman cattle and probably explains why this phenomenon was not noticed in the Friesian cow used experimentally. The clinical syndrome observed in both Fig. 2: Heart: widening of interfibre spaces (indicative of oedema) and swelling of fibres; mild the natural cases and the experimental interstitial fibrosis (arrow). HE ×300. case appear to be consistent with acute cardiac glycoside poisoning. Experimen- tal cases of the bufadienolide-containing, closely related Bryophyllum (= Kalanchoe) was the most probable cause of the the finding of abundant K. lanceolata with tubiflorum poisoning in cattle have been unexplained deaths that occurred on the evidence that it had been grazed, were treated successfully with activated affected farm. The investigation was lim- highly suggestive of a common aetiology. charcoal6. While oral gavage with milk ited by the availability of only one experi- Differential diagnoses for the syndrome appeared to alleviate field cases treated mental animal of a different breed for should include bufadienolide poisoning early, the mechanism of action is not clear clinical trials. However, the similarity of due to other plants such as Urginea san- and requires further investigation. the field and experimental syndromes, guinea (Liliaceae), Cotyledon and Tylecodon This study indicates that K. lanceolata especially the pathological lesions, and spp. (Crassulaceae). 0038-2809 Jl S.Afr.vet.Ass. (1997) 68(1): 18–20 19 ACKNOWLEDGEMENTS REFERENCES 4. Kellerman T S, Coetzer J A W, Naudé T W 1. Anderson L A P, Schultz R A, Joubert J P J, 1990 Plant poisonings and mycotoxicoses of We thank Messrs R B Drummond and Prozesky L, Kellerman T S, Erasmus G L, livestock in southern Africa. Oxford Univer- S Mavi, National Herbarium, Harare, for Procos J 1983 Krimpsiekte and acute cardiac sity Press, Cape Town specialist botanical assistance, and Messrs glycoside poisoning in sheep caused by 5. McKenzie R A, Dunster