Cystinuria in Scottish Deerhounds
Three years ago, two dogs I bred (see pedigree) were diagnosed with cystinuria, a genetic kidney defect. Recently, a third dog from the same litter was diagnosed with the same condition, although he continues asymptomatic as he nears his tenth birthday.
If you have a Scottish Deerhound who might have any kind of bladder stones, please arrange to have him or her tested for this condition. If you are a Scottish Deerhound breeder, be sure to screen each of your dogs for this condition; it has shown up in a number of pedigrees in North America as well as in Europe and the UK. The screening test costs only $18 and you do not even need to take the dog to the vet. Visit the Cystinuria Testing Site maintained by the Scottish Deerhound Club of America to find out how you can participate.
If you are purchasing a puppy, insist that the mother and father of the puppy are tested clear for cystinuria by the University of Pennsylvania. There is no other test that is reliable. Since this test is only $18 and completely safe for the dog, there is no reason for a breeder not to have done this simple screening. Cystinuria is a life-threatening condition, and surgery to treat its complications and prevent future recurrences can cost thousands of dollars.
If you are a stud dog owner, do not allow unscreened bitches to be bred to your dogs. Likewise, bitch owners should not use stud dogs who have not been screened for cystinuria.
While there have been instances of false positives and false negatives, in most cases a false positive is the result of a known drug reaction. A positive urine test for cystine is almost always indicative of cystinuria in the dog. A negative test is not conclusive, but until a DNA test is developed to determine carrier status, the University of Pennsylvania test is the best tool we have available to us. More information is available in an Update from the University of PA Scottish Deerhound Cystinuria Study. Please do not allow concern over the reliability of the test prevent you from screening your dog. The results are confidential, and only by screening large numbers of deerhounds can we get the information we need to develop a DNA test for carrier status. Furthermore, if your dog does test positive, it will enable you to be proactive in watching for any signs that he is developing stones.
If you have, or bred, a deerhound who is diagnosed with cystinuria, please contact John Dillberger, DVM, who is coordinating this effort for the Scottish Deerhound, and ask her how you can participate in the ongoing deerhound cystinuria study at the University of Pennsylvania. This will contribute to our search for a genetic marker that we can use to screen dogs. Such a marker could identify dogs at an early age who have cystinuria and help breeders reduce the incidence of cystinuria in Deerhounds.
What is Cystinuria?
Very basically, cystinuria is a genetic defect in which the kidney is not able to process a basic amino acid, cystine, correctly. Affected dogs are born with this condition but in most cases it takes many years before things get bad enough that we notice it. Many dogs, mostly females, but even some males, live their whole lives with the condition and no symptoms at all.
Over time, the unprocessed cystine in the urine clumps together to form stones. These stones can, especially in males, block the urinary tract. This is a life-threatening condition and requires surgery.
However, even before the blockage has occurred, the presence of crystals, gravel, and stones in the bladder can cause irritation, discomfort, and bladder infections.
What Causes Cystinuria?
Cystinuria is genetic. It is not caused by diet or drugs or anything else. Dogs are born with it and it is inherited, although the mode of inheritance is not yet known in our breed.
What Can You Do About It?
The stones form most easily in normal canine urine, which has an acid pH. Keeping the urine alkaline can slow down stone formation, so many veterinarians recommend giving a diet and supplements that keep the urine alkaline. In my own personal opinion, I don't think this is a good idea. Alkaline urine in and of itself can cause or worsen bladder irritation and infections. When we put our deerhound, Skye, on a diet with supplements that produced an alkaline urine, he developed a bladder infection and also, his teeth developed tartar and gum irritation. However, my view is not standard veterinary opinion and I am not a vet.
Skye had an operation known as an urethrostomy, where a new urinary outlet was created for him. He now urinates like a female. Some people believe this means the penis was removed, but this is NOT correct. He simply no longer urinates through his penis, but through his urethrostomy instead. Many, probably most, dogs who have this surgery will continue to lift their legs to urinate or mark, instead of squatting like a female. This means their urine can easily run down the inside of their leg. You must pay special attention to keeping these dogs' legs clean on a daily basis, or every time they urinate. We use health food store "baby wipes" for this purpose. Others use the Depends wipes made for human adults with incontinence problems. A quick rinse with a hose is probably best. At least weekly we wash him thoroughly with warm water from a hose and a gentle canine shampoo.
Conventional veterinarians will probably recommend a diet such as Hills U/D. I have serious problems with this diet, due to several factors.
One, I don't like foods that use ingredients that are unfit for human consumption.
Two, I don't think it's healthy for dogs to have a lifelong diet of processed foods only.
Three, I have unresolved concerns about keeping protein levels low for giant breed dogs. Some cardiologists have questioned if there might not be a link between low protein diets and some forms of heart disease, including cardiomyopathy, in some dogs. I am not suggesting this is a proven connection, but it is something to consider.
Four, I also question feeding diets low in methionine, which is the precursor to cystine, as methionine is required in the canine diet so they can synthesize taurine, which is essential to heart health. This would apply to home-prepared diets as well as prescription diets.
Five, based on my research, I do not believe diet is really that effective of a tool in reducing the incidence of cystine stone formation.
Drugs and Supplements
We experimented with a supplement called Biotic pH+ from Wysong. It is intended to alkalinize the urine. There are other supplements on the market, and even some drugs, which also have this effect. Some people use baking soda for this purpose.
I have come to the conclusion that while an alkaline urine may help keep stones from forming, it will not entirely prevent it, and has health risks I feel are serious, including increasing the risk of bladder infections and irritation.
There are two drugs available that will bind cystine in the urine and reduce the chances of it forming stones. The more popular one is a-MPG (mercaptopropionylglycine, also known as tiopronin; brand name Thiola). It is used in people with cystinuria. A 14-year Swedish study of 86 dogs with cystinuria found that in 86 percent of the dogs, stone re-formation was prevented with this drug. (A. Hoppe & T Denneberg; "Cystinuria in the Dog: Clinical Studies during 14 Years of Medical Treatment," Journal of Veterinary Internal Medicine, Jul-Aug 2001. Department of Small Animal Clinical Sciences, Swedish University of Agricultural Sciences, Box 7037, S-750 07 Uppsala, Sweden.)
Thiola is what is known as an "orphan drug" and can be difficult to obtain. Information on obtaining the drug can be found here: Thiola. A veterinary prescription is required.
Skye was in excellent health on a home-prepared, raw, grain-free diet, which is the diet we feed all our dogs. We have fed raw, home-prepared foods to our dogs since 1986. When Skye was diagnosed, we did seek out meat sources that are low in methionine (beef, lamb, rabbit), as well as vegetables that tend to produce alkaline urine. We fed him large amounts of alkalinizing vegetables and reduced the overall amount of protein in his diet. We also used a supplement that alkalinizes the urine.
When Skye developed a bladder infection, inflamed gums, and tartar on this diet, we returned him to the same diet he had always eaten, although still primarily using low-methionine meats. He went years without an infection after being back on his regular diet, and his inflamed gums improved. However, he continued to have problems with tartar.
In January of 2003, about three and a half years after his diagnosis and urethrostomy, Skye began to show signs of being ill. A sonagram showed no stones, but his prostate was enlarged and cystic, and a UTI was diagnosed. We opted for a course of antibiotics, but there was no improvement. Skye's condition worsened rapidly and drastically, and he dropped from 105 to 67 pounds. We took him repeatedly to both the emergency vet and our regular internal medicine specialist, but he kept going downhill. He was hospitalized at our insistence, but they were reluctant even to do diagnostics that would require sedation, due to a previous adverse reaction to sedation and his present poor condition. They had to catheterize him, and at one point drained almost a cup of pus out of his bladder. The vets, both internists and surgeons, told us there was nothing they could do for him. We were specifically told there were no surgical options available.
I refused to accept this and in desperation contacted Dr. Gary Brown, the surgeon in Fremont, CA who had done Skye's original surgery. Dr. Brown listened to the details and said, "Tough case. Tough case. I love a tough case. We won't give up on the little guy." He had our former veterinarian, internal medicine specialist and greyhound breeder Helen Hamilton, call us, and just hearing Helen's voice comforted me. The other vets had faxed some of Skye's records over, and she said, "Christie, go put him in the car right away and bring him to me."
My mother left immediately, and she got Skye out of the other veterinary hospital, where he had been for three days, and drove him at once to Helen's practice, three hours away. They admitted him, did more tests, and found that he did indeed have many stones, in his bladder and also in his prostate gland. The urethral wall had ruptured (the pus drained at the previous vet hospital, which they thought had come from the bladder, had actually come when the catheter had gone through the urethral wall into an abscess). They arranged for immediate surgery. Dr. Brown removed the stones (subsequently found to be cystine stones) from Skye's bladder and prostate gland, neutered him to reduce the size of the prostate, repaired the prostate, and then used omentum, the vascularized fatty lining of the stomach, to repair the ruptured urethral wall. It was now a waiting game, because if the rupture wouldn't heal, Skye would not be able to live.
Skye was catheterized, and hospitalized, for a week. Every day either my mother or I went to the hospital to spend time with him, and try to coax him to eat the homecooked meals we brought. His condition was so poor that his inability to eat wsa compromising his chances of recovery. At one point we also were able to have a veterinary acupuncturist treat him in the hospital, which relieved some swelling in his limbs and also caused him to rest more peacefully.
After one week, tests revealed that Skye's urethra had sealed and he was discharged to us. He rapidly put his weight back on and is now extremely well, running and playing like a dog half his age (he will be 10 in July of 2003).
There are no words to express our gratitude to Dr. Hamilton and Dr. Brown, not only for their great skill, but also for their refusal to give up on Skye. Despite the three hour travel time through some of the worst traffic in the San Francisco Bay Area, Skye will remain in Dr. Hamilton's care from now on.
Dr. S. Gary Brown DVM, Diplomate American College of Veterinary Surgeons, can be contacted in Fremont, CA, at 510-657-6343.
Dr. Helen B. Hamilton DVM, MS, Diplomate American College of Veterinary Internal Medicine is at 510-657-9151, also in Fremont, CA.
Note: In July of 2004, just after his 11th birthday, Skye suffered a recurrence of bacterial prostatitis, probably but not definitely related to his underlying cystinuria. While the bacteria in his urine did resolve after a course of antibiotic therapy, his symptoms did not get any better and he appeared to be in grave pain. Pain medication did not give him any relief, and after nearly 4 weeks of trying, we made the difficult decision not to put him through anymore. On August 16, 2004, we said goodbye to our Skye. We'll miss him forever, and hope that everyone with a Scottish Deerhound with cystinuria will find the way a little clearer after reading about Skye's experiences.
For more general information on cystinuria, visit the excellent Cystinuria Information page on the website of the Mastiff Club of America.
John Dillberger, DVM, contributed to this article.