Canis ISSN: 2398-2942

Vitamin A toxicity

Synonym(s): Vitamin toxicity

Contributor(s): Dawn Ruben, Patricia Talcott

Introduction

  • Vitamin A toxicity is uncommon.
  • It is a chronic disease usually due to ingestion of feed containing high levels of vitamin A Vitamin A for several weeks.

Pathogenesis

Etiology

  • Vitamin A toxicity occurs when excessive amounts of vitamin A are ingested over a period of several weeks (over 14 weeks).
  • Improperly mixed food or ingesting food with high concentrations of vitamin A, such as raw liver or cod liver oil, can lead to vitamin A toxicity.

Predisposing factors

General
  • All animals are susceptible but vitamin A toxicity is more likely to occur in cats.

Pathophysiology

  • High levels of vitamin A will induce chondrocytes to produce increased amounts of extracellular matrix proteins and will also inhibit intramembranous and endochondral ossification. This leads to dystrophic calcification. The physeal areas of the long bones may fuse early. Exostoses and fusion of the sternum and/or vertebrae may be found.
  • High levels of vitamin A also leads to lysosomal instability. Enzymes are released and the cartilage matrix is reduced, resulting in chondromalacia.

Timecourse

  • This is a chronic disease and generally takes over 14 weeks of excessive vitamin A exposure to develop.

Diagnosis

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Treatment

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Prevention

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Outcomes

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Further Reading

Publications

Refereed papers

Other sources of information

  • Roder J D (2004) Vitamins. In:Clinical Veterinary Toxicology.(ed) Plumlee KH. Mosby. St. Louis, p 330.
  • Osweiler G D (1996) Toxicology. Lippincott, Williams & Wilkins. Philadelphia. p 154.

 

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