RICIN

Ricinus communis (castor oil bush, castor oil plant, palma christi). A member of the plant family EUPHORBIACEAE. Annual herbaceous plant with lobed, palmate leaves. Flowers are in clustered panicles, developing into spiny capsular fruits enclosing hard, shiny, oval seeds marbled brown and black. Castor oil is obtained from the seeds. Cultivated as a garden and ornamental indoor plant, to a lesser extent for its oil content.

Animals most affected
Dogs, (all species).

Etiology
Ingestion of the seeds or, more frequently, ingestion of oilcakes which are used as fertilizer and appear to be very appetizing to dogs.

Toxicity
The seeds contain a proteinaceous phytotoxin, ricin, located in the albumen fraction. It is this non-liposoluble fraction of ricin which persists in the oilcake.

Oral doses:
LD in g/kg body weight:
seeds

cattle (adult)	2
calves	0.5
horses	0.1
sheep	1.25
goats	5.5
pigs	1.3
chickens	1.4
rabbits	1.0
dogs	0.6-5

oilcakes

cattle (adult)	3
horses	3
sheep	2.5
pigs	5-6
hens	40
rabbits	2
dogs	3.5

Clinical features

In dogs, after a latent period of 12 to 72 hours:

vomiting, violent and protracted hanmorrhagic diarrhoea with colic, abdominal pain and cramps, oliguria;
prostration, exhaustion, a typhus-like state progressing towards death within 2-3 days, following a period of convulsions.

Lesions

severe, intense protracted gastroenteritis;
haemorrhages of the mucosae of the gastrointestinal tract;
degeneration of the liver and kidneys;
generalized congestion.

Treatment
Antidote: anti-ricin serum but which is restricted in its availability. Therefore symptomatic care only, which may not be very effective.

Case summaries
A veterinary surgeon examined two dogs which had eaten some ricin oilcake and had vomited within half an hour of ingestion. One of the two dogs had gastric lavage using a protective agent based on aluminium phosphate. The following day their condition deteriorated: the dogs were prostrate, with discoloured buccal and ocular mucosae. Urine analysis showed the presence of albumen and a pH of 5. At 36 hours post-exposure, both dogs died following gross intestinal haemorrhages. No treatment, symptomatic or otherwise, could have prevented this fatal outcome.
A puppy swallowed the remainder of a sack of ricin seed-cake which had been open for 5 years. The next morning he presented with profuse diarrhoea and was in a semi-conscious state. Despite treatment, the puppy died by mid-morning.