Bovis ISSN 2398-2993

Allium spp toxicity

Synonym(s): Allium ampeloprasum (leek), Allium canadense (Canadian garlic), Allium cepa (onion, shallot), Allium fistulosum (spring onion), Allium moly (golden garlic, lily leek), Allium sativum (garlic), Allium schoenoprasum (chive), Allium sphaerocephalon (round headed leek), Allium vineale (field garlic, wild garlic, crow garlic), Allium ursinum (wild garlic, wood garlic, ramsons)

Contributor(s): Nicola Bates , James Adams

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  • Cause: ingestion of Allium species including onions, leeks and garlic.
  • Signs: signs associated with hemolytic anemia.
  • Diagnosis: base on history, clinical signs and possibly the odor of onion or garlic on breath, feces or urine.
  • Treatment: supportive.
  • Prognosis: generally good with removal from source and supportive care.



  • Cattle appear to be particularly susceptible to Allium poisoning compared to goats and sheep.

Predisposing factors


  • Cattle will readily eat Allium species, sometimes in preference to other forage.


  • All parts of the plant are toxic.
  • Trauma to the plants (chewing, crushing) converts organosulphoxides present to a variety of organic sulphur compounds including n-propyl disulphide, allyl propyldisulphide and allyl sulphide.
  • n-Propyl disulphide, depletes the enzyme glucose-6-phosphate dehydrogenase (G6PD) within erythrocytes. The protective effect of the antioxidant, glutathione, is diminished as the glutathione remains in the oxidised state.
  • Thiol free radicals and reactive oxygen species denature hemoglobin which precipitates within the cell resulting in the formation of Heinz bodies .
  • Erythrocytes that contain Heinz bodies are fragile and more likely to lyse. They are removed from the circulation by the recticuloendothelial system, thereby inducing anemia.
  • Free radicals produced by these processes oxidise hemoglobin to methemoglobin.
  • In addition, the amino acids S-meth- and S-prop(en)ylcysteine sulphoxide (SMCO) are hydrolysed in the rumen to thiosulphate which is further metabolised to dipropyl disulphides and dipropenyl disulphides. These compounds are potent hemolytic agents.
  • Cooking, dehydration or spoilage of Allium species does not reduce toxicity.


  • Signs may occur suddenly within 24 hours if a large quantity has been ingested but it is more common for signs to occur after several days.
  • Recovery usually occurs within a week, but can be longer in severe cases (up to 2 weeks).


  • Allium toxicosis may occur anywhere the plants are grown and typically occurs where cattle are fed a large quantity over a short period of time. 


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Further Reading


Refereed Papers

  • Recent references from PubMed and VetMed Resource.
  • El-Sayed Y S, El-Okle O S M, Hassan S M H & Bakir N M A (2015) Poisoning of cattle feeding on Allium ampeloprasum (Egyptian kurrat). Journal of Veterinary Science & Medical Diagnosis 4, pp 4.
  • Borelli V, Lucioli J, Furlan F H, Hopers P G et al (2009) Fatal onion (Allium cepa) toxicosis in water buffalo (Bubalus bubalis). Journal of Veterinary Diagnostic Investigation 21, pp 402-405 PubMed.
  • Aslani M R, Mohri M & Movassaghi A R (2005) Heinz body anaemia associated with onion (Allium cepa) toxicosis in a flock of sheep. Comparative Clinical Pathology 14, pp 118-120.
  • Van der Kolk J (2000) Onion poisoning in a herd of dairy cattle. Veterinary Record 147, pp 517-518 PubMed.
  • Carbery J T (1999) A case of onion poisoning in a cow. New Zealand Veterinary Journal, 47, pp 184.
  • Rae H A (1999) Onion toxicosis in a herd of beef cows. Canadian Veterinary Journal 40, pp 55-57 PubMed.
  • Fredrickson E L, Estell R E, Havstad K M, Shupe W L & Murray L W (1995) Potential toxicity and feed value of onions for sheep. Livestock Production Science 42, pp 45-54.
  • Chakrabart A & Basak D N (1994) Onion poisoning in a heifer - a case report. Livestock Adviser 19, pp 36-37.
  • Munday R & Manns E (1994) Comparative toxicity of prop(en)yl disulfides derived from Alliaceae: possible involvement of 1-propenyl disulfides in onion-induced hemolytic anemia. Journal of Agricultural and Food Chemistry 42, pp 959-962.
  • Lincoln S D, Howell M E, Combs J J & Hinman D D (1992) Hematologic effects and feeding performance in cattle fed cull domestic onions (Allium cepa). Journal of the American Veterinary Medical Association 200, pp 1090-1094 PubMed.
  • Lund L J, Gibson G M & Turner R G (1991) Leek taint in beef carcases. Veterinary Record 128, pp 263 PubMed.
  • Hothi D S, Arneja J S, Chawla J S (1980) Onion (Allium cepa) poisoning in bullocks. Indian Veterinary Journal 57, pp 690-692.
  • Hutchison T W S (1977) Onions as a cause of Heinz body anaemia and death in cattle. Canadian Veterinary Journal 18, pp 358-360 PubMed.
  • James L F & Binns W (1966) Effect of feeding wild onions. Journal of the American Veterinary Medical Association 149, pp 512-514 PubMed.
  • Verhoeff J, Hajer R, van den Ingh T S (1985) Onion poisoning of young cattle. Veterinary Record 117, pp 497-498 PubMed.