Wurroit Bedlingtons

Wurroit Bedlingtons

Copper Toxicosis, Updates

Copper Toxicosis in Bedlington Terriers. (September 2015)

Copper Toxicosis is an autosomal recessive disease which may affect Bedlington Terriers. Affected dogs (generally) accumulate copper in the liver over an extended time which slowly results in the destruction of the liver.

PLEASE NOTE: from the results table it will be seen that only result type “D”, 2:2, not carrying the deletion, is the only DNA result “Guaranteed” as a Copper Toxicosis CLEAR animal.

Early means of testing for this disease was by the use of Liver Biopsy performed on dogs at around 12 months of age. The dog was anaesthetised and a small sample of liver removed and tested for copper levels. This method of testing however has been found to be not a conclusive test for determining the CT status of a dog. This is because dogs which were genetically “affected” by the disease did not necessarily have copper liver levels which would be interpreted as a “positive” result for CT.

Interestingly, some affected dogs with high liver copper levels may not have recognised symptoms of the disease other than high copper levels. Other affected dogs with “marginal” or slightly elevated levels of liver copper have died of Copper Toxicosis.

Regardless of the “margin of error” in using Liver Biopsy to determine CT status of progeny and as a means of determining if Breeding Stock were clear of the disease. This was done by using a dog or bitch known to be affected by the disease to a dog of unknown status. The resultant pups were then tested at 12 months of age. If all of the pups were shown to be “storing” copper in the liver then the dog of unknown status would then be identified as an affected dog. Obviously, this process produced a number of pups that were affected by the disease and the process was unable to identify “carriers” within the litter.

CO 4107

This test is used to identify “markers” at a location on the DNA strand which have been regularly associated with Copper Toxicosis. The markers were labelled as markers 1 and 2 where the type 1 marker is most often associated with the “normal” or functioning gene and the type 2 marker is strongly associated in lines of dogs that are affected by the disease.

It should be noted that;

There are some dogs that were identified as 1:1, ie two copies of the “normal” gene that are affected by Copper Toxicosis.

Also, there are some 2:2 dogs that were clear of the disease.

Therefor, while the CO 4107 test is a strong indicator of CT status in Bedlington Terriers, it is not a guarantee that the dog will be either affected, carrier or clear.

With the advent of the above test pups were granted “Clear by Parentage” status if the DNA of both the Sire and the Dam were 1:1. The reason behind the “Clear by Parentage” is that pups can only inherit a share of what the parents have, ie, if both parents only have “type 1” DNA then the pups can only have “type 1” DNA, and, dogs with “type 1” DNA, ie 1:1, were assumed and/or reported by many breeders to be “CLEAR” without knowing if the markers (1 or 2), were linked to the “clear/normal” or “affected/deletion” gene. While type 2 markers can now be identified as “normal” or “deletion detected” there is no test capable of identifying a similar deletion on type 1 DNA.

COMMD 1, MURR 1 Deletion Test

This test is a further development of the “linked” marker test above. The test is able to identify a deletion the genetic information which seems to be necessary for dogs to process/eliminate copper from the liver. This “deleted” section of genetic information has only been identified on “Type 2” DNA. There has been no recorded instance of a “parallel” deletion on those animals that are identified as having two copies of “Type 1” DNA which is normally associated with a dog of “clear” status, but which are in fact “affected” by Copper Toxicosis.

VetGen (USA genetics LAB), provide the following results;

Result Type	Definition	Marker	Explanation
A	Not carrying the deletion	1:1	Extremely small risk of having inherited the unknown mutation responsible for “bad 1’s”. Breeding considered safe unless mating pair are from line(s) known to have clinically affected 1:1 animals. Very high probability this animal does not have the disease.
B	Not carrying the deletion.	1:2	Extremely small risk of having inherited the unknown mutation responsible for “bad 1’s”. Breeding considered safe unless mating pair are from line(s) known to have clinically affected 1:1 animals and that parent also contributes a “bad 1”. Cannot have the disease.
C	Carrying one copy of the deletion.	1:2	Extremely small risk of having inherited the unknown mutation responsible for “bad 1’s”. Can produce affected offspring if mated to another animal with an identical result type or result types E or F. NOTE: if result is a “bad 1” and research reveals in the future that the mutation is also from the same gene as the “bad 2” deletion, this this result would indicate an affected animal as opposed to a carrier.
D	Not carrying the deletion.	2:2	Cannot have the disease, will not produce affected offspring, Thus is the optimal breeding choice.
E	Carrying one copy of the deletion.	2:2	Cannot have the disease but can produce affected offspring if mated to another animal with an identical result type or result types C or F
F	Carrying two copies of the deletion.	2:2	Is affected with the disease but may or may not exhibit symptoms. Can produce affected offspring if mated to another animal with an identical result type or result types C or E

The above table sourced from VetGen here;

https://www.vetgen.com/canine-ct-marker.html

Of further interest Shirley Davies (Honeymist) has developed the following pamphlet on Bedlingtons and Copper Toxicosis.

http://myweb.tiscali.co.uk/bedlingtonpictures/Health3.pdf

Home Page   About Us   Our Dogs   Photo Album

Puppies   From Birth to You   Managing your Wurroit Bedlington   Puppies, November 2017

Gemma & Raven Pups, 2019   Wurroit Bedlingtons, newest additions, 2014 +   Bedlingtons in Colour   Conditions And Diseases

Copper & Copper Toxicosis   Copper Toxicosis, Updates   Beasley and C.T.   Genes & Genetic Diversity

Bedlington Health Considerations   Sorcha and Cushings Disease   Straight From The Heart   Guest Book   Links Page   Contact Form

Contact Details
Bob & Erica Whitehead
Alice Springs, NT, Australia
Phone : 0407 713 026
Email : [email protected]