Death of a South American fur seal (Arctocephalus australis) after the ingestion of toads--evaluation of toad poisoning by toxicological analysis

Animals in zoological gardens are at risk of severe and even lethal poisoning when they accidentally ingest toads. Here we report the case of an eleven month old male South American fur seal (Arctocephalus australis) which was found dead in its outdoor enclosure in the zoo of Dortmund, Germany. Autopsy revealed the presence of two adult, partly digested common toads (Bufo bufo) in the stomach. Toxicological analysis of the stomach content using high performance liquid chromatography coupled to time-of-flight mass spectrometry (LC-TOF MS) proved the presence of bufadienolides, the major cardiotoxic components of toad poisons. Using electrochemical luminescens immunoassay (ECLIA) compounds equivalent to digitoxin were detected in the blood sample confirming the absorption of toad poison components from the intestines into the circulation potentially leading to cardiac failure. In zoological gardens special precautions are necessary to protect non-native animals from encountering toads and the risk of poisoning, particularly in early spring, the spawning period of the toads.

[Determination of cinobufagin and resibufogenin in liver tissue by HPLC-MS/MS]

OBJECTIVE

To develop a sensitive and accurate assay for detecting cinobufagin and resibufogenin in liver tissue using high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS).

METHODS

The homogenization of liver tissue with internal standard dexamethasone was extracted with dichloromethane. The extracts with methanol were purified through ProElut C18 solid phase extraction and tested in positive electrospray ionization with multiple reaction monitoring of HPLC-MS/MS.

RESULTS

The good linear relationship of cinobufagin and resibufogenin in liver tissue were 1-204 ng/g and 1-206 ng/g, respectively. The minimal detection threshold (S/N > or = 3) of this method was 0.3 ng/g for both cinobufagin and resibufogenin. The matrix effect was 96.5%-126.7%. The extraction recovery coefficient was 70.0%-82.3%. The precision of intra-day and inter-day was less than 10%.

CONCLUSION

This method is sensitive and reliable, and can be used in forensic toxicological analysis.

An interesting case of cardiotoxicity due to bufotoxin (toad toxin)

Consumption of toads for their aphrodisiac effect is a common practice in Laos, China and in some parts of India. Toad secretions from parotid and skin contains toxin similar to cardiac glycosides. It results in bradycardia and cardiac dysfunction leading on to death in some cases. We report a case of toad poisoning in a young previously healthy male.

Urginea maritima L (Squill): a poisonous plant of North Africa

Poisoning of livestock by ingestion of Urginea maritima L (squill), a common plant of coastal Mediterranean regions of North Africa is reviewed.

Efficacy of digoxin specific Fab fragments (Digibind) in the treatment of toad venom poisoning

Chan Su, a traditional Chinese medication, and Love Stone, a topical aphrodisiac, are both made from dried venom of the toad bufo bufo gargarizans and contain bufalin, cinobufotalin, cinobufagin, and other cardioactive steroids of the bufadienolide class. Deaths have occurred following ingestion of these products and the clinical course resembles digoxin toxicity. The purpose of this study was to determine the efficacy of digoxin specific Fab fragments in treating Chan Su poisoning. An ethanolic extract was prepared from Chan Su. Digoxin specific Fab fragments were reconstituted in normal saline to a concentration of 80 mg/ml. An approximate LD90 dose was determined in preliminary experiments. Mice were then randomly divided into a treatment group of 15 mice and a control group of 30 mice. The treatment group was pretreated with 20 ml/kg of digoxin specific Fab fragment solution by intraperitoneal injection at t = 0, followed by 10 ml/kg of digoxin specific Fab fragments intraperitoneal at t = 30 min. The control group was pretreated with equal volumes of intraperitoneal normal saline at the same times. Immediately following the 30 min injection, both groups were given the estimated LD90 dose of Chan Su extract by subcutaneous injection. An endpoint of survival at 6 h was chosen after preliminary results showed that all deaths occurred in the first 4 h. All 30 of the control mice had seizures followed by death compared to 11 seizures and 7deaths in the 15 treatment mice. These results were statistically significant by Fisher's exact test (p = 0.00003 for mortality and p = 0.009 for seizures). Digoxin specific Fab fragments are effective in the treatment of Chan Su poisoning in mice and may be effective for poisoning by other cardioactive steroids of the bufadienolide class.

Krimpsiekte in a sheep following a single dose of Tylecodon ventricosus (Burm. f.) Toelken and the isolation of tyledoside D from this plant species

Tylecodon ventricosus induced severe respiratory distress in two penned sheep without any electrocardiographic abnormalities being recorded. Based on the results it appears as if T. ventricosus predominantly induces the neuromuscular syndrome referred to as krimpsiekte. A single, relatively large intraruminal dose of 10.0 g/kg induced krimpsiekte in one sheep. Treatment with 5.0 g/kg activated charcoal on two consecutive days did not prevent the development of krimpsiekte. A bufadienolide, tyledoside D, was isolated from semi-dried plant material.

Intoxication after ingestion of toad soup: report of two cases

Intoxication after ingestion of toad is rare, but it results in severe morbidity and high mortality. Recently, we encountered 2 children, one a 15-month-old boy and one a 20-month-old girl, who were fed cooked toad (Bufo melanostictus) soup. The boy expired of ventricular fibrillation. The girl presented with varying degrees of A-V block with congestive heart failure which, however, was completely resolved after intensive treatment. In our experience, early identification and intervention are necessary to decrease absorption of toxins; to correct hyperkalemia. Dysrhythmia should be treated with atropine, antiarrhythmic agents, and a temporary pacemaker, in order to avoid lethal results.

Krimpsiekte, associated with thalamic lesions, induced by the neurotoxic cardiac glycoside, cotyledoside, isolated from Tylecodon wallichii (Harv.) Toelken subsp. wallichii

The specific neurotoxic principle of Tylecodon wallichii (Harv.) Toelken subsp. wallichii, the cause of krimpsiekte in small stock, was isolated and identified as the previously described cumulative bufadienolide, cotyledoside. Krimpsiekte was experimentally induced in two sheep by the repeated intravenous administration of cotyledoside at the rate of 0.01-0.015 mg/kg body mass. On day 9, both animals developed clinical signs typical of krimpsiekte, which is characterized by tremors, paresis and recumbency. Both sheep had difficulty in controlling their hindquarters when attempting to lie down. No significant electrocardiograph abnormalities were detected during the experiment which confirms that cotyledoside at low doses does not overtly affect the electrical activity of the heart. No gross lesions were observed in the sheep. The most significant microscopic lesions comprised mild brain oedema and pronounced vacuolation of the white matter of thalamic nuclei. These lesions might explain some of the motor function deficiencies clinically observed in this syndrome. The previously held contention that these neurotoxic cardiac glycosides are indeed the cause of krimpsiekte is, therefore, confirmed.

Treatment of toad venom poisoning with digoxin-specific Fab fragments

Toxicity from toad venom poisoning is similar to digoxin toxicity and carries a high mortality rate. We report on six previously healthy men who developed vomiting and bradycardia after ingesting a purported topical aphrodisiac. Each patient had positive apparent digoxin levels and the first four patients died of cardiac dysrhythmias. The last two patients recovered following treatment with digoxin Fab fragments. We analyzed samples of the purported aphrodisiac and found that it was identical to Chan Su, a Chinese medication made from toad venom. To our knowledge, this is the first reported use of digoxin Fab fragments to treat toad venom poisoning.

Centers for Disease Control and Prevention (CDC). Deaths associated with a purported aphrodisiac--New York City, February 1993-May 1995

During February 1993-May 1995, the New York City Poison Control Center (NYCPCC) was informed about onset of illness in five previously healthy men after they ingested a substance marketed as a topical aphrodisiac; four of the men died. These cases were investigated by the New York City Department of Health, the New York City Department of Environmental Protection, and the Food and Drug Administration (FDA). Four cases were referred to the NYCPCC and one case to the New York City medical examiner's office. The decedents died from cardiac dysrhythmias, and all five patients had measurable levels of digoxin* detected in their serum. Digoxin had not been prescribed for therapeutic purposes for any of these patients, and none had medical conditions associated with endogenous digoxin-like immunoreactive substances. The purported aphrodisiac contains bufadienolides, naturally occurring cardioactive steroids that have digoxin-like effects. This report describes three of the five case reports, summarizes the investigations of the five cases, and underscores the health risks associated with inappropriate use of preparations containing digoxin-like substances.

[Acute poisoning by scilliroside]

A 43-year-old man, with no history of cardiac disease, deliberately ingested 4 tablets of a rodenticide containing 12 mg of scilliroside. Vomiting appeared a few minutes later and persisted for 48 hours. At the 20th hour, when he was admitted, EKG revealed a complete atrio-ventricular block which disappeared only on the 4th day. The repolarization abnormalities characteristic of digitalization persisted still further until the 12th day.

Specific anti-digoxin Fab fragments: an available antidote for proscillaridin and scilliroside poisoning?

The purpose of this study was to evaluate the capacity of specific anti-digoxin Fab fragments to bind to and neutralize scilliroside and proscillaridin in acute poisoning. Apparent affinity constants were determined with values of 2.6 10(8)M-1 for scilliroside and 3.8 10(7)M-1 for proscillaridin. These results are in accordance with a possible in-vivo neutralization of these toxins.

Cardiac glycoside poisoning in sheep caused by Urginea physodes (Jacq.) Bak. and the isolated physodine A

Urginea physodes (Jacq.) Bak., a species closely related to or possibly synonymous with U. pusilla, is described and its distribution given. Four bufadienolides were isolated from U. physodes and the approximated LD50 and cumulative effect of some of them determined in guinea pigs. The most toxic one proved to be mildly cumulative. Typical signs of acute cardiac glycoside poisoning, involving the locomotory, gastro-intestinal, respiratory and cardiac system, were seen in the field cases and/or were experimentally induced by the plant. Similar signs could also be induced by injecting the isolated bufadienolide, physodine A, to a sheep.

The toxicity to cattle and bufadienolide content of six Bryophyllum species

Cardiac glycoside poisoning was produced in calves given (in descending order of toxicity) flower heads of the hybrid Bryophyllum (Kalanchoe) daigremontianum x B. tubiflorum, of B. pinnatum, of B. tubiflorum (from previous work), whole plant of B. fedtschenkoi, flower heads of B. daigremontianum and whole plant of B. proliferum. For each plant (except B. tubiflorum), 2 calves were each given a single dose of 20 g wet weight per kg bodyweight. By using high performance liquid chromatography, the bufadienolides (cardiac glycosides) bryotoxin A, B and C were detected and assayed in the flower heads and leaf plus stem of B. tubiflorum and in the roots of B. tubiflorum, the hybrid and B. pinnatum. Only bryotoxins B and C were detected and assayed in the flower heads and leaf plus stem of the hybrid, B. daigremontianum and B. pinnatum. No bryotoxins were detected in B. fedtschenkoi. Bryotoxin A and a mixture of bryotoxins B and C from B. tubiflorum flowers were used as standards in the chromatographic assay. Comparing the results of the calf toxicity experiment with the amounts of bufadienolide measured in the plants suggests that bryotoxins A, B and C probably account for the observed disease, but that B. pinnatum and B. fedtschenkoi contain at least one other cardiac glycoside.

Isolation and characterization of and some observations on poisoning by bufadienolides from Cotyledon orbiculata L. var. orbiculata

The approximate LD50 and cumulative effect of 4 bufadienolides, isolated from Cotyledon orbiculata, were determined in guinea-pigs. Two of the bufadienolides proved to be mildly cumulative. One of the mildly cumulative bufadienolides induced subacute intoxication with some signs of krimpsiekte when injected intravenously into a sheep over 13 days. In the sheep, the paralysis was accompanied by signs of malaise, such as electrocardiographic changes and ruminal stasis.

An outbreak of Cotyledon orbiculata L. poisoning in a flock of Angora goat rams

An acute outbreak of C. orbiculata L. poisoning in a flock of 16 Angora Goat rams is described. Typical signs of acute bufadienolide cardiac glycoside toxicity were manifested and 6 animals died. In the 2 animals examined histopathologically multiple foci of myocardial degeneration and necrosis were present. Treatment consisted, inter alia, of drenching with a mixture of activated charcoal, potassium chloride and a commercial preparation, Universal Antidote (Centaur) and parenteral administration of atropine sulphate.

Krimpsiekte and acute cardiac glycoside poisoning in sheep caused by bufadienolides from the plant Kalanchoe lanceolata Forsk

Three toxic bufadienolides , one characterized as hellibrigenin 3-acetate, have been isolated from Kalanchoe lanceolata Forsk. Typical signs of cardiac glycoside poisoning, involving the gastro-intestinal, neuromuscular and cardiovascular systems, could be induced by drenching the milled plant to sheep. Such signs could also be induced by dosing the bufadienolides to sheep or by injecting them into both guinea-pigs (subcutaneously) and sheep (intravenously). The specific paretic syndrome, krimpsiekte , on the other hand, was reproduced only by the repeated intravenous administration of smaller doses of the 2 unknown bufadienolides to sheep. Histopathological examination revealed a mild to severe multifocal cardiomyopathy in sheep receiving plant material or bufadienolides .

The experimental production of krimpsiekte in sheep with Tylecodon grandiflorus (Burm.f.) Toelken and some of its bufadienolides

Six bufadienolides were isolated from Tylecodon grandiflorus ( Burm .f.) Toelken . The paretic syndrome, krimpsiekte , could be induced in sheep either by repeated oral administration of small quantities of plant material or the intravenous injection of small quantities of certain bufadienolides . A mild to moderate, acute to subacute, multifocal cardiomyopathy was evident in sheep poisoned by both the plant and the bufadienolides .

Electrocardiographic changes on sublethal poisoning of Vacor and Silmurin to Bandicota bengalensis

A single sublethal dose of Vacor (1 mg/rat) or Silmurin (50 microgram/rat) brought about dissimilar changes in cardiac physiology of bandicoot rats. Delayed myocardial repolarization and stress on cardiac tissues were noticed. Elevation of S-T segment above the isoelectric axis diagnostic of recent myocardial infarction was observed. Vacor and Silmurin induced differential changes in heartbeat; Vacor poisoning resulted in bradycardia, whereas Silmurin tachycardia. It is inferred that Vacor deaths may be due to bradycardia associated with atrioventricular block and that of Silmurin to delayed myocardial repolarization and tachycardia.