Copper Toxicosis (Bedlington Terrier Type)

Test Overview:

Copper toxicosis is an inherited disease that affects the ability of the liver to process and excrete copper into the bile.  Copper is highly toxic to cells above certain concentrations, and if it cannot be excreted it builds up in the liver cells until it reaches toxic levels.  This disease is especially common in Bedlington terriers, and has been reported as an autosomal recessive disorder.  However, recent research suggests that more than one gene is responsible for producing copper toxicosis in dogs (i.e. it may be a polygenic disease).  This disease occurs occasionally in Bedlington terrier crosses. There are three recognised forms of copper toxicosis:  Asymptomatic copper toxicosis. These dogs show no clinical signs of disease (they are asymptomatic) although a liver biopsy and liver copper level would indicate that they are “affected”.  Many dogs seem to fall into this category, and may live normal lives.  However they may progress to clinical disease at any time. Acute copper toxicosis. In this case a dog becomes acutely ill with liver failure, often at a relatively young age (ie 2-3 years).  This may be precipitated by a stressful incident.  The sudden release of copper from liver cells also causes red cell breakdown, causing a haemolytic crisis.  These dogs often die within a few days despite treatment. Chronic copper toxicosis. This commonly occurs in older dogs, and shows as a gradual onset of worsening liver failure.  Signs are often vague or non-specific, and may not be detected until liver damage is very advanced.  Signs include lethargy, reduced appetite, thirst, weight loss, intermittent vomiting, diarrhoea, then with late disease jaundice and fluid accumulation in the abdomen, with depression and possibly other neurologic signs. If animals can be detected early enough, treatment with copper chelating agents in the diet can minimise or prevent signs of copper toxicosis.  Once copper toxicosis has developed and liver failure is evident, it cannot be cured.  Medication and dietary modification can help to manage the signs of the disease.  Diagnosis of copper toxicosis in the past has been by liver biopsy, which has necessitated general anaesthesia and invasive surgery.  A DNA test (the COMMD1 test) has recently been developed for the detection of carrier and affected Bedlington terriers, however it is known from recent research that there is at least one other gene responsible for copper toxicosis, and there is no direct evidence that COMMD1is even involved in copper metabolism.  Research is continuing.  Current recommendations for breeders include ensuring puppy purchasers are aware of the limitations of the COMMD1 test, and ideally to continue liver biopsy testing of their breeding stock.  Liver biopsy currently remains the only way to definitively tell if a dog is affected by copper toxicosis.