INHERITED KIDNEY DISEASE IN BULL TERRIERS
Breeders of Bull Terriers come and go and new ones enter the breed so for all you new breeders welcome and here’s something to take on board in your quest for the best of the best. As for the rest of us. Maybe a quick refresher on the subject? And maybe it is time seven years after the article was written for all our breed clubs to push for research.
Appeared in the N. E Bull terrier club magazine 2004
By Dr. Caroline O’Leary
University of Queensland
Inherited Kidney disease (IKD) has been reported in many breeds of dog including the Bull Terrier and Miniature Bullterrier as well as in people.
There are many different types of kidney disease, inherited (or genetic) faults being only one cause. Infections, poisons, some drugs, non-genetic cancers, liver, pancreas, uterine, heart disease or many other diseases can cause kidney disease.
The inherited condition in Bull Terriers can occur in very young (less than six months) middle aged or very old animals. Some dogs can be ten years plus and have the faulty gene in their make-up, pass it on to some of their pups, and may appear normal to their owners. These animals may live to a ripe old age with no-one suspecting they have the disease.
Signs of kidney failure that are common to both types of IKD and to other causes of kidney failure include the following.
• poor appetite- dullness or lethargy-weight loss or stunted growth-poor hair ¾ coat- vomiting/diarrhoea-foul breath and mouth ulcers-muscle twitching and convulsions-drinking
excess water and passing too much urine-owners often notice an increase in the urine passed overnight-pale gums (anaemia)-dehydration (sticky gums).
There are two types of IKD in Bull Terriers.
The first type of IKD is polycystic kidneys where the kidneys contain fluid filled cysts (or balls of fluid) which can be seen by looking at the kidney, for example by using an ultrasound machine, where they may be seen as ‘black holes’ inside the kidneys. At what age this is commonly detectable is not known. While it is possible to detect the defect in some dogs as puppies, it may be that in some animals it is not obvious until the dog is much older. In this disease a urine test will not pick all affected dogs, so an ultrasound is ideal.
The second condition is nephritis where the kidneys may look fairly normal until a biopsy (or small piece of tissue taken from a live animal) is examined under a microscope. It is not possible to diagnose this disease on the basis of an ultrasound examination. A urine test, or kidney biopsy are the best tests for this disease.
Both conditions are thought to be inherited in an autosomal dominant fashion, which means that only one parent has to have the fault for half of the litter to be affected. If both parents have the fault ¾ or more of the pups may be affected.
Because of the way these conditions are inherited, there is no point in condemning whole kennels or bloodlines. As an affected dog may produce unaffected puppies and these animals do not have the faulty gene/s, these animals are fine to be bred with as long as they are regularly tested. They have the virtues present in the line without the ‘taint’
Of the faulty gene/s.
Dogs that have either of these inherited problems SHOULD NOT be bred from.
There is no test available that can say for sure that dogs are unaffected below one year of age. It is possible some affected dogs are not detected until they are 3 or 4 years old.
Even leaving the ethical problems out of deliberately breeding affected dogs that must be euthanised or given to homes with the knowledge that they are affected by a deadly genetic disease, these dogs cannot be reliably cleared until they are at least 1 year old and possibly 3-4years old.
These dogs would have to be kept until this age before being bred.
Dogs affected by both these conditions may have bloody urine on and off, and the vast majority of dogs with nephritis and some dogs with polycystic kidneys will have abnormal levels of protein in their urine (this is shown with a UP/C or urine protein to creatinine ratio). Only a few who are late in the course of the disease will have abnormal blood results. In both these conditions, how fast the disease progresses and how severe it is varies from dog to dog..
The Urine Protein to Creatinine ratio (UP/C) is a very sensitive test and is valuable in detecting nephritis and some polycystic kidney disease before signs of kidney failure appear (so lengthening the dog’s good quality of life) and hopefully before the dog is bred. Using this test will hugely decrease the nephritis problem within one generation. This is especially so as it is possible to prevent popular affected stud dogs spreading the faulty gene/s widely by detecting them much earlier than was possible before with the BUN test.
Animals with a high UP/C need to have a full urinalysis completed to rule out other causes than inherited kidney disease. If the UP/C is high and thee are no other obvious causes (eg reproductive problems, bladder problems) an ultrasound examination and possibly a kidney biopsy will give the full answer.
The UP/C test is easy to use and relatively cheap, making it an ideal screening test for nephritis. We believe most of the affected bull terriers have a high UP/C result by the time they are 1 year old. There are possibly occasional dogs that are affected, that only have a high UP/C once they are 3 or 4 years old, but there are no published records of this. (at the time of going to press) Life long retesting is recommended at this stage.
A lot of hard work needs to be done to investigate both diseases. The relationship between these two diseases needs to be looked at, the value of current testing procedures needs to be continually monitored and, hopefully in the future a genetic test will be developed that can be done once in young pups to predict which ones have the faulty gene/s.
There is no effective cure for either condition. Prevention by breeding dogs free of these inherited faults is the best solution.
At this stage palliative treatment to maintain comfortable life for as long as possible is the usual treatment for IKF.
If the kidney failure is recognised early in its course the following can be tried;
• Constant access to fresh water- controlled protein, phosphorous and salt diet( use only with care in growing dogs)- phosphate binders to bind phosphorous in the diet- water soluble vitamins (especially B vitamins)- hormones for anaemia- medication for nausea and stomach ulcers- blood pressure medication if necessary. Some of the reason so little is known about inherited diseases include;
• Hard to detect carriers of faulty genes cheaply, accurately and early in the life before dogs are sold or used for breeding- differences between dogs in the way the disease appears-need for comment from the Breed Clubs to support research into the problem and develop strategies to breed soundly
• A certificate system to encourage breeding from unaffected dogs and a national register appears to be the best solution