Updates and Notices:
Updates on Liver Shunt Research Programs:
9/05 Dear Yorkie Supporters:
Here is an update of the happenings at University
of Tennessee regarding liver shunts in Yorkies. I realize it's a very long
letter, but I hope getting the information directly to you will help
clarify our programs.
We have several ongoing programs regarding liver shunts in Yorkies and other breeds:
First and foremost is our Angel Fund. This fund was started with the help of Terri Shumsky. Terri truly was a Yorkie Angel; through her efforts dozens of owners were assisted with medical and surgical care of their shunt puppies or were directed to places where they could receive excellent treatment. The fund was set up for three purposes: to help determine the hereditary nature of liver shunts, to help support surgery costs for owners, and to help support clinical projects to improve detection and survival of dogs with shunts. The fund has been used for all of these purposes, and continues to be supported by compassionate Yorkie and non-Yorkie dog owners and enthusiasts. In fact, YTNR recently made a $2,500 donation to the fund to keep it going, and a recent clinical project has added another $3000. Many owners of Yorkies and other affected breeds have also made contributions.
The hereditary studies were also supported by a 1 year grant from the AKC. With this grant, we performed pedigree and epidemiology studies. We found that incidence of shunts was twice as high in dogs that were inbred, but that there was no single family line that could be identified as a shunt carrier. We also found that Yorkshire terriers had a 36 times greater risk of having congenital shunts than all breeds combined, and the odds of having a shunt was 58 times that of mixed breed dogs. With the funding we also developed our "breeding family". We had several Yorkies with corrected shunts that we hoped could be bred to produce puppies so that we could determine mode of inheritance.
So far, only Tilly ("Maggie Mae") produced puppies - a healthy male and a healthy female (both neutered)- from her breeding with Tuffy. Our second male ("Mouse") was just castrated because he developed a prostate infection and changes in his testicles. Another male had to be castrated for behavioral reasons (marking, fighting, etc.). Sassy has had several one-day heats, but has never had cytologic changes that indicate she is ready to be bred. Mary ("Kissy") just went in to heat Friday and will be spending the next two weeks with Tuffy in the honeymoon suite at the local hotel. One of the girls ("Mocha") has been placed in a home with breeder, in the hopes that an experienced breeder will be more likely to recognize the signs of heat in her and therefore will be able to bring her to Tuffy (or visa versa) at the appropriate time.
The other females that we received for possible breeding were too small and too sick to be considered- either they were not going to reach 4 pounds or their liver disease was so severe (and did not resolve with shunt surgery) that we did not want to endanger their lives; therefore, they were spayed. All of the dogs are living with Tennessee Yorkie people- many with veterinary faculty and staff- that have had Yorkies before. All are living in homes and are well loved. We do not do home inspections for placement and I do not do any home inspections after placement; we trust the people that are caring for these dogs and have seen the excellent condition of their other pets.
So, out of the one successful breeding, we have learned that the characteristic for shunts is not simple dominant, simple recessive, or sex linked, and that the disease can skip generations (although we do not know whether these healthy pups are carriers of the gene). The AKC grant was completed 2 years ago, and the results have been published in 2 scientific journals (attached below), so we are no longer doing pedigree studies. We've decided we will not accept any more dogs for breeding, but we hope to start looking at the actual gene assays, or assisting other researchers with this, using our Yorkie family and their offspring. Webmasters were asked several weeks ago to remove the $250 breeder incentive from their sites; hopefully that has been done. On a sadder note, we just lost Tilly last week to a liver lobe torsion (a portion of her liver twisted and she went into shock). She also had a uterine infection, and we were getting ready to spay her when she died. Everyone was devastated- it's hard to lose such a sweet family member.
Our second project is determining better ways to diagnose shunts. As you may know, nuclear scans (rectal scintigraphy) can tell us whether there is shunting or not, but they cannot tell us the type of shunt (i.e. whether it is surgically correctable, or whether there are multiple acquired shunts present). We have recently developed a better technique ("transplenic scintigraphy") for scanning dogs, and it seems to be able to diagnose multiple acquired versus single congenital shunts. The scan is quicker and uses less radioactivity, making it safer for us and the dogs. This funded project has just won the National Radiology Award, and two publications have been submitted. This study was also funded by an outside research grant that allowed us to pay for scintigraphy in over 40 dogs; we will continue to assess the dogs we've evaluated and hope to present our expanced results at next year's national surgery meeting.
Our third project is determining why some dogs have complications after surgery. This funded study is looking at blood sugar and hormone levels in our patients and may help us to predict which dogs will have problems immediately after surgery or later in life. Most often, dangerously low blood sugar affects Yorkies within 6 hours after the surgery, but other breeds are also affected. This study is ongoing and will continue until we can find the answer to this dangerous problem.
What is the bottom line of all our programs? We have determined that shunts are hereditary, that we might decrease the risk with less inbreeding, that it is passed as a genetic trait through multiple genes or through a gene that only expresses itself under certain conditions. With all of our experience that we have gained, our mortality rate is 1% for surgical correction (compared to 2-14% at other hospitals), and we see no fatal seizures after surgery in dogs (compared to 3-7% in other hospitals). Our dogs require no anti-seizure medication before surgery, and usually stay 1-2 nights in the hospital after surgery (compared to 2-4 at other hospitals) because of low postoperative complication rates. Our average surgery time is half that of most other referral hospitals, and 85% of our dogs are clinically normal 4-6 months after surgery.
University of Tennessee will continue to lead the country in clinical studies of dogs with shunts and we will continue to try and help Yorkie owners and other dog lovers by keeping the costs low. This gives us plenty of animals to evaluate, and tons of experience that will continually make us better. Currently we are giving owners an estimate of $1400-1600; this includes bloodwork, scintigraphy, anesthesia, surgery, and 2 days aftercare. We expect this estimate to rise every year with inflation, but have found that our prices are usually much less than at other clinics. Our administration may request that we increase these costs to reflect our expertise in the area (and to make them more equivalent to "market"- usually $2200-$4000) but so far we've been able to convince them of the value that information from these patients provides. (It also allows us to help more dogs!)
If you have any questions about these programs, please contact me directly by e-mail. Please feel free to forward this to anyone in TSFML, YTNR, etc, so that everyone will be well informed.
Dr. Tobias, DVM, MS, Diplomate ACVS
Professor, Small Animal Surgery
University of Tennessee College of Veterinary Medicine
See attached file for more information:
PSS heredity final.doc
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