Canis ISSN: 2398-2942

Immunology: C3 deficiency

Contributor(s): Michael Day, Richard Squires


  • RARE autosomal recessive immunodeficiency disease.
  • Cause: characterized by deficiency of serum C3 (complement component).
  • Signs: increased incidence of sepsis and local bacterial infections in homozygous animals.
  • Predominantly gram-negative bacteria involved and Clostridia Clostridium perfringens.
  • Reported in single colony of Brittany Spaniel (see Sources - Blumet al).



  • C3 deficiency is associated with inability to opsonize and lyse bacteria.
  • Animals homozygous for this genetic defect have no detectable C3.
  • Heterozygotes have approximately 50% of normal levels.
  • Clinical signs are seen in homozygotes.


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Further Reading


Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Ameratunga, R, Winkelstein J A, Brody L, Binns M, Cork L C, Colombani P & Valle D (1998) Molecular analysis of the third component of canine complement (C3) and identification of the mutation responsible for hereditary canine C3 deficiency. J Immunology 160 (6), 2824-2830 PubMed.
  • Guilford W G (1987) Primary immunodeficiency diseases of dogs and cats. Comp Contin Educ 9 (6), 641-650 VetMedResource.
  • Blum J R et al (1985) The clinical manifestations of a genetically determined deficiency of the third component of complement in the dog. Clinical Immunology and Immunopathology 34 (4), 304-15 PubMed.

Other sources of information

  • Felsberg P J (1992)Primary imunodeficiencies.In:Current Veterinary Therapy XI: Small Animal Practice.Eds: Kirk R W & Bonagura J D. Philadelphia: W B Saunders. pp 448-453.