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By:
Maria Leliñho under the guidance of Dr. Karen M. Tobias, DVM, MS,
Diplomate ACVS
Developing
fetuses in all mammals have a large shunt that carries blood through the
liver to the heart. Since
the mother's liver does the work of filtering out toxins, storing sugar,
and producing protein for her unborn babies, liver function is not
needed in the fetus. Under normal circumstances, the shunt closes down shortly
before or after birth as the newborn's liver begins to work. However, in some cases the shunt doesn't close down properly,
or forms around the outside of the liver, thereby causing a hereditary
birth defect known as a “congenital portosystemic shunt” or CPSS.
Because
the blood bypasses the liver in a dog with a shunt, toxins may build up
in the bloodstream or kidneys. The
animal lacks the necessary materials to give it a ready source of energy
that it needs to help it grow. Clinical
signs are often seen at a young age and include small stature, poor
muscle development, behavioral abnormalities (circling, disorientation,
unresponsiveness, staring into space, head pressing), seizures, and
quiet demeanor. Other less
common signs can include drinking or urinating too much, apparent
blindness, diarrhea, and vomiting.
In some animals the signs are associated with protein intake
while others are diagnosed when they take a long time recovering from
anesthetics (i.e. barbiturates) or sedatives (i.e. acepromazine). Yet
other animals show no signs until they are older, when they develop
bladder and kidney infections and stones.
Over
the years spanning from January 1980 through February 2002, Veterinary
Teaching Hospitals have been collecting information concerning affected
dogs, including the Yorkshire Terrier breed, as they are presented and
diagnosed with CPSS. This
information is maintained in a Veterinary
Medical Data Base (“VMDB”) in order to track and identify
which breeds are at greater risk.
Based
upon the statistical information contained in the VMDB as it relates to
the Yorkshire Terrier breed, the
following facts and findings have recently been presented to the Journal
of the American Veterinary Medical Association and portions have
also been accepted for publication in the Journal of the American Animal
Hospital Association.
Congenital
shunts were reported in 0.18%
of all dogs and 0.05% of mixed breed dogs.
The annual proportion of dogs diagnosed with CPSS in the VMDB
increased ten-fold from 0.05% (or 5 in every 10,000) in 1980 to 0.5% (or
5 in every 1,000) in 2001. Yorkshire
Terriers accounted for 20.1% of dogs with CPSS and were the most
frequently reported.
Overall,
when compared with mixed breeds, 33 purebred breeds were more likely to
have a diagnosis of CPSS. Alarmingly,
in the United States, Yorkshire Terriers have almost a 36 times greater
risk of developing shunts than all other breeds combined and the breed
had the greatest total number of diagnoses of CPSS.
The Yorkshire Terrier breed was among the highest proportional
diagnosed breed maintaining a rate of 483 affected dogs in 16,538 – a
rate of 2.9%.
Vets,
breeders and owners of Yorkshire Terriers (as well as any other breed at
higher risk for CPSS) should be aware of the following points concerning
this disease:
1.
Clinical signs as discussed above;
2.
Methods for diagnosis, which include blood tests that measure
BUN, albumin, liver enzymes, and bile acids;
3.
Appropriate testing, which includes scintigraphy, portogram,
Doppler ultrasound, and/or biopsy;
4.
Treatment, which consists of several methods, the most successful
being the ameroid constrictor. Other
options include placement of a suture or cellophane band around the
shunt or coils inside of the shunt.
(In all cases of diagnosed CPSS, it is highly recommended that
the affected dog should be spayed or neutered so as not to run the risk
of breeding such affected dogs, and that the parents of the dog not be
bred to each other); and,
5.
Medical management, which consists of, but is not limited to, a
protein-restricted diet, the use of lactulose, and possibly antibiotics.
Additional
studies are currently underway (by way of breeding program) to determine
the mode of inheritance, or when and how the gene is passed genetically
and whether the gene is passive or recessive, in the Yorkshire Terrier
breed. As such, there is a
strong need for affected females and/or for families of affected dogs
for this program. The
importance of such a program will also provide insight on a potential
testing procedure that can be implemented by breeders to ensure they are
breeding non-CPSS dogs or carriers in their line.
Any
breeders wishing to be a part of this study should contact Dr. Tobias
directly at the University. Total
confidentiality is assured and pedigree information is not required for
this program. The program
offers free travel/transport arrangements to the University of Tennessee
and 100% coverage of all surgical and future medical management costs in
addition to a fee-for-dog-relinquishment for all approved affected dogs.
Anyone
wishing to learn more about CPSS in the Yorkshire Terrier or about the
breeding program can contact Karen M. Tobias, DVM, MS, Diplomate ACVS at
the University of Tennessee College of Veterinary Medicine (865)
974-5525. Additional
in-depth and detailed information about CPSS can be obtained at the
College of Veterinary Medicine’s website at: http://www.vet.utk.edu/clinical/sacs/shunts.shtml.
A recognised expert in treatment of Liver Shunt is Dr.
Karen Tobias..
Click her banner below for her brochure explaining more
about liver shunts
A recognised expert in treatment of Liver Shunt is Dr.
Karen Tobias..
Click her banner below for her brochure explaining more
about liver shunts
A recognized expert in treatment of Liver Shunt is Dr. Karen Tobias.
Click
HERE for her
brochure explaining more about liver shunts.
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