Canine Cystinuria is an autosomal recessive
disorder that affects a dog's ability to filter cystine out of urine.
Normally, tubules in the kidney are responsible for reabsorption
of cystine, filtering it out of the urine. However, in dogs with
Canine Cystinuria, the tubules are unable to transport the cystine,
allowing it to accumulate in the urine. Cystine is generally insoluble
in the acidic conditions of canine urine, allowing it to crystallize
and form caliculi, also known as stones.
Not every dog that has the mutation responsible for Cystinuria will
exhibit symptoms. Stones causing inflammation and blockage are often
more common in males, due to their long, narrow urethra. Females
exhibit symptoms much less frequently, and may be completely asymptomatic.
Canine Cystinuria affects over 60 breeds of dogs. Research suggests
that Newfoundlands carry a more severe form of this disease than
other breeds. Other breeds often do not experience symptoms until
about 4-5 years in age; however, Newfoundlands may begin experiencing
problems as early as 6 months to one year of age. Also, Newfoundlands
are much more likely to experience recurring urethral blockages
that could require surgical intervention.
In the Newfoundland breed, the cause
of Cystinuria is a single nucleotide polymorphism that occurs in
the SLC3A1 gene which causes a premature stop codon. Cystinuria
is a recessive disorder, meaning that the dog must have two copies
of the defective gene to suffer from the disease. Because Cystinuria
is a recessive disorder, a dog can also be a carrier of this disease,
meaning it carries one copy of the mutation, but does not display
any symptoms. A carrier dog can pass on this mutation to their offspring,
and if they mate with another carrier dog, can produce offspring
affected by Cystinuria.
Animal Genetics offers DNA testing and detection
of the gene mutation responsible for Canine Cystinuria in the Newfoundland breed.
US per sample.
Collect sample using buccal swabs provided by
Animal Genetics. Ensure that the dog has not eaten within a few
hours of sample collection. Any food particles can inhibit the test.
Rub each of the swabs along the inside of the dog's mouth for 10-15
seconds, and allow the swabs to dry thoroughly. Label the provided
envelope with the dog's name, and place the swab inside it. Download
and complete a submission form for each sample and send along with
payment to Animal Genetics for testing.
Results are given using the following symbolic
The dog carries two copies of the mutant gene and is homozygous
for Cystinuria. The dog is affected by Canine Cystinuria.
Both the normal and mutant copies of the gene detected. The
dog is a carrier for Canine Cystinuria.
Tested negative for the Cystinuria mutation.