Toxicology Brief managing common poisonings in companion animals

PEER-REVIEWED Kalanchoe species poisoning in pets Geof Smith, DVM, PhD, DACVIM

alanchoe is a genus of 150 to TABLE 1 Common Kalanchoe Species Found in North America 200 plant species, most of K which are native to southern Scientific Name Common Names Africa, Madagascar, and Australia. In Kalanchoe blossfeldiana Florist’s kalanchoe, Madagascar widow’s-thrill the past, the genus was divided into three genera: Kalanchoe, Bryo- Kalanchoe daigremontiana Devil’s backbone, mother of millions, Mexican hat plant phyllum, and Kitchingia. But today Kalanchoe beharensis Feltbush, velvetleaf most botanists recognize it as one Kalanchoe delagoensis Mother of millions, chandelier plant genus.1 In the United States, Kalan- choe species are primarily ornamentals Kalanchoe fedtschenkoi South American air plant, lavender scallops and houseplants, but some have es- Kalanchoe pinnata Air plant, Mexican love plant, cathedral bells caped cultivation and can be found in Kalanchoe gastonis-bonnieri Palm beachbells, donkey ears the wild, especially in Florida and Hawaii. Table 1 lists the most common Kalanchoe beauverdii Sotre-Sotry Kalanchoe species found in North Kalanchoe prolifera Blooming boxes America. Kalanchoe laciniata Christmastree plant

Plant characteristics long; flower clusters can last FIGURE 1 Although the plants vary, most Kalan- for weeks to months. Most choe species are erect, growing shrubs Kalanchoe species are easy to (Figure 1). These perennial plants gen- propagate from leaf or stem erally have thick, green, succulent fo- cuttings. Many species have liage and clusters of small flowers (Fig- plantlets (miniature plants at ures 2 & 3). The plants are popular with the end of flowering stems) florists because they can be forced to growing in the notches of the bloom at any time of the year, including leaf margins; these plantlets holidays. Kalanchoe species’ flowers are so prolific that they some- can be many colors, but red, yellow, times escape into the wild. pink, orange, and white are the most common. The plants’ bloom time is Toxicity Kalanchoe species contain “Toxicology Brief” was contributed by cardiac glycosides and are Geof Smith, DVM, PhD, DACVIM, toxic to animals. In South Department of Population Health and Africa and Australia, where Pathobiology, College of Veterinary Medicine, North Carolina State University, these plants are found in the Raleigh, NC 27606. The department wild, cattle and sheep poi- 2-4 editor is Petra A. Volmer, DVM, MS, DABVT, sonings are common. Toxi- DABT, College of Veterinary Medicine, cosis occurs primarily in the University of Illinois, Urbana, IL 61802. summer months because the 1. A Kalanchoe species shrub. Notice the thick green leaves and flowers contain a much the small clusters of red flowers.

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FIGURE 2 FIGURE 3

2. The flowers of the Kalanchoe blossfeldiana plant, exchange for potassium. When the upset and generally occur beginning a the most common ornamental Kalanchoe species pump is inhibited, intracellular sodium few hours after plant ingestion. The in the United States. concentrations begin to increase, and glycosides in Kalanchoe species can 3. Kalanchoe species plants (white flowers) in an potassium concentrations decrease. also act directly on the gastrointestinal ornamental garden with tulips (red flowers). The increased intracellular sodium can tract, causing hemorrhagic enteritis, be exchanged through the sodium- abdominal pain, and diarrhea. These higher concentration of glycosides calcium exchanger for calcium, which signs appear fairly consistently in the than the stems, leaves, or roots do.2 improves contractility. Because of this early stages of toxicosis, and cardiac Although the toxic dose of Kalanchoe effect, these glycosides (e.g. digoxin) signs such as arrhythmias, tachycar- species in small animals is unknown, can be used pharmacologically as posi- dia, and dyspnea may appear if suffi- in calves the lethal dose is estimated tive inotropes to increase myocardial cient plant material is ingested. As the to be 7 g of flowers/kg body weight contractility. However, these changes in toxicosis progresses, severe arrhyth- or 40 g of leaves/kg body weight.2,3 In ion flux can cause a progressive de- mias with atrioventricular block may the United States, Kalanchoe species crease in electrical conductivity through occur. Animals may develop severe represent little risk to livestock be- the heart, resulting in irregular heart ac- weakness and cold extremities, col- cause the plants are not commonly tivity and, eventually, termination of lapse, and eventually die because of found in pastures. However, house- cardiac activity. In toxic doses, cardiac cardiac arrest. Usually the course is hold pets, including dogs, cats, and glycosides increase sympathetic dis- rapid (12 to 24 hours), but in some birds, are susceptible because the charge to the heart and automatic cases, signs may persist for four or plants are used in landscaping and rhythmicity, thereby potentiating ven- five days. kept as houseplants. tricular arrhythmias. Published reports of Kalanchoe In summary, bufadienolides inhibit species toxicosis in small animals are the sodium-potassium pump of the my- rare. In cattle, the most common clini- Mechanism of action ocardial cell membrane, leading to fre- cal sign is sudden death due to the Kalanchoe species’ toxicity is primarily quent and irregular depolarization of toxin’s profound cardiac effects.2-4 due to a group of bufadienolide com- the cell. This results in disorganized Other reported signs observed in pounds, including bryotoxins, bryo- cardiac electrical activity, manifesting in cases of acute Kalanchoe species toxi- phyllins, and bersalgenins.1,5 Bufa- a variety of arrhythmias and eventually cosis include collapse, cyanosis, ar- dienolides are cardiac glycosides that leading to cardiac arrest. rhythmias, dyspnea, and persistent di- are similar to digitalis compounds. Inhi- arrhea. In South Africa, krimpsiekte, a bition of the cellular membrane neurologic syndrome, has been well- Clinical signs sodium-potassium pump (Na+,K+- described in sheep and goats associ- ATPase enzyme system) produces the Clinical signs of Kalanchoe species ated with long-term ingestion of cardiotoxic effects. In the heart, this toxicosis include depression, exces- Kalanchoe species. The syndrome in- system pumps sodium out of the cell in sive salivation, and gastrointestinal volves progressive paresis of the limbs

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and neck (torticollis). Animals even- Antiarrhythmic drugs such as potas- tually become paralyzed and gener- sium chloride, procainamide hy- ally have to be euthanized.6 The con- drochloride, lidocaine hydrochloride, dition has also been reported in dogs or atropine sulfate may be indicated in South Africa.7 In the United States, when specific arrhythmias are pres- neurologic signs, including nystag- ent. Treating digoxin toxicosis with mus, delirium, mild seizures, and digoxin-specific antibodies (Digibind; tetany, have been reported in dogs GlaxoSmithKline) has been de- consuming Kalanchoe species scribed,11 but it is unknown whether plants.8 these antibodies would effectively bind the cardiac glycosides found in Kalanchoe species. Diagnosis and treatment Kalanchoe species toxicosis is diag- REFERENCES nosed based on a history of known 1. Burrows, G.E.; Tyrl, R.J.: Crassu- laceae. Toxic Plants of North America. exposure (i.e. observed ingestion, Iowa State University Press, Ames, 2001; identification of chewed plants, iden- pp 385-391. tification of plant material in vomitus) 2. McKenzie, R.A.; Dunster, P.J.: Hearts and flowers: Bryophyllum poisoning of and compatible clinical signs. Al- cattle. Aust. Vet. J. 63 (7):222-227; 1986. though no definitive tests are avail- 3. McKenzie, R.A. et al.: The toxicity to able to confirm Kalanchoe species cattle and bufadienolide content of six Bryophyllum species. Aust. Vet. J. 64 ingestion, assays to detect other car- (10):298-301; 1987. diac glycosides from gastrointestinal 4. Reppas, G.P.: Bryophyllum pinna- contents have been described.9,10 It is tum poisoning of cattle. Aust. Vet. J. 72 (11):425-427; 1995. unknown whether these chromato- 5. Oelrichs, P.B. et al.: Isolation and graphic tests can detect the cardiac identification of the toxic principles in glycosides found in Kalanchoe Bryophyllum tubiflorum (Kalanchoe). Poisonous Plants. Proc. Third Interna- species. tional Symposium on Poisonous Plants Treatment of Kalanchoe species (L.F. James et al., eds.). Iowa State Uni- toxicosis is symptomatic and support- versity Press, Ames, 1992; pp 288-292. 6. Anderson, L.A. et al.: Krimpsiekte and ive. Gastric lavage or vomiting acute cardiac glycoside poisoning in should be induced in asymptomatic sheep caused by bufadienolides from the dogs and cats as soon as possible plant Kalanchoe lanceolata Forsk. Onder- stepoort J. Vet. Res. 50 (4):295-300; 1983. after a suspected ingestion. Activated 7. Kellerman, T.S. et al.: Heart. Plant charcoal may be given after emesis. Poisonings and Mycotoxicoses of Live- If clinical signs are already present, stock in Southern Africa. Oxford Univer- sity Press, Cape Town, South Africa, supportive therapy is indicated. Al- 1988; pp 83-130. though intravenous fluids are neces- 8. Plumlee, K.H.: Plant hazards. Vet. sary to maintain cardiac output, fluids Clin. North Am. (Small Anim. Pract.) 32 (2):383-395; 2002. containing calcium should be used 9. Galey, F.D. et al.: Diagnosis of olean- with caution because calcium may der poisoning in livestock. J. Vet. Diagn. augment the effects of the cardiac Invest. 8 (3):358-364; 1996. 10. Holstege, D.M. et al.: Multiresidue glycosides. Animals should be kept screen for cardiotoxins by two- as quiet as possible to avoid further dimensional thin-layer chromatography. stress on the heart. If cardiac abnor- J. Agric. Food Chem. 48 (1):60-64; 2000. 11. Senior, D.F. et al.: Treatment of acute malities are identified during auscul- digoxin toxicosis with digoxin immune tation, electrocardiographic monitor- fab (Ovine). J. Vet. Intern. Med. 5 ing is highly recommended. (5):302-303; 1991. ■

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