Complement 3 Deficiency

Complement C3 deficiency is a pathology that in dogs increases susceptibility to recurrent bacterial infections and renal disease (glomerulonephritis).


Dogs with complement C3 deficiency tend to have recurrent bacterial infections, including pneumonia and urinary tract infections. This deficiency also increases the risk of kidney disease (glomerulonephritis).

Disease Management

Should your dog show any symptoms you should see your veterinarian for evaluation. Although there is no specific treatment for complement C3 deficiency, antibiotics can be used to control bacterial infections. Monitoring of renal function and control of hypertension with a low sodium diet is advised.

Genetic basis

This disease follows an autosomal recessive mode of inheritance. Autosomal recessive inheritance means that the dog, regardless of sex, must receive two copies of the mutation or pathogenic variant to be at risk of developing the disease. Both parents of an affected dog must carry at least one copy of the mutation. Animals with only one copy of the mutation are not at increased risk of developing the disease, but may pass the mutation on to future generations. Breeding between dogs carrying genetic variants that can cause disease, even if they do not show symptoms, is not recommended.

Technical report

Here we analyze the c.2136del variant in the C3 gene that codes for the complement component C3, which is involved in innate immunity. In the study conducted by Ameratunga et al. this alteration was shown to cause complement 3 deficiency in the Brittany Spaniel breed of dog.

Most affected breeds

  • Brittany Spaniel


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