Elevated Renal Function DNA Blood Typing & More
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ELEVATED RENAL ENZYMES IN BIRMAN CATS Dr. Danielle Gunn-Moore For a number of years I have been interested in Birman cats and their kidneys. This started when it was noticed that blood samples from many apparently healthy Birman cats had elevated urea and creatinine levels. While increases in urea and creatinine usually indicate a significant degree of kidney damage the affected cats did not appear to be ill.
Incidence of raised creatinine levels: To investigate this further we performed a prospective survey of healthy Birman cats. The cats were recruited with the assistance of the Southern and South Western Birman Cat Club and via direct contact with a number of individual Birman breeders. Initially, 112 clinically healthy cats were blood sampled. They ranged in age from eight weeks to 12 years; 78% were less than six years of age, 18% were less than six months of age; 50% were entire females, 14% neutered females, 23% entire males, and 13% neutered males. The cats came from 19 separate households. Only creatinine levels were assessed because urea is more inherently variable and can be altered by feeding. The study found statistically significant evidence of elevated creatinine levels in apparently healthy Birman cats. The incidence appeared to relate to age, with over 80% of Birmans less than six months old having creatinine levels above the normal range for that age, while 30% of adults appeared to be similarly affected.
Prospective study: Sixty-eight of the cats were then reassessed 18 months later. Information was available for all of these cats, but repeat samples were obtained from only 43. This was because some had moved to new homes, were unavailable on the day of sampling, or had died. Two of the cats had died from renal failure. The study showed that in the majority of cats the raised creatinine changed little with time. The stability of the condition can also be seen when looking at a number of individual cats for which we have urea and creatinine levels over a long period of time. Table 1 shows details of two cats, Esther and Koska, both of whom were first sampled at nine years of age, and who, despite having raised urea and creatinine levels went on to live long and happy lives. Koska eventually died of kidney failure, aged nearly 16 years of age, while Esther is still well, aged 17 years! Interestingly, while in the majority of cases the raised kidney enzymes appeared to change little with time, the finding may still reflect underlying renal disease. In support of this, two of the cats (one aged 10 years, the other aged only eight weeks), while apparently healthy at the time of first testing, developed progressive kidney failure within a few months, and had to be euthanased. In addition, I have seen several young Birmans with clinical renal failure; the most severely affected being under two years of age, with clinical signs often developing shortly after routine neutering. In some cases, entire families appear to be affected. For example, Figure 1 and Table 2 detail two related families. In one litter of four apparently healthy kittens three of the kittens were found to have raised kidney enzymes at eight weeks of age (a1, 3 and 4). When the kittens were neutered at six months of age, all four were given intravenous fluids and antibiotics. Two of the kittens recovered well (a2 and a4), while the other two were slow to recover (a1 and a3), and one (a1) progressed to terminal renal failure within six months. A related cat (the dam’s sister) was mated to the same sire, and gave birth to a litter of three kittens; b1 and b2 developed acute renal failure within one month of being castrated. b2 failed to respond to supportive treatment and died two weeks later. b1 responded initially, but developed chronic renal failure and had to be euthanased at one year of age. A second litter brother (b3) also had raised kidney enzymes, but was clinically healthy at the time of blood sampling.
Summary: This study suggests that many Birman cats may have some degree of renal dysfunction, which may or may not result in signs of ill-health, and which may or may not progress with time. It has not yet been possible to determine an underlying cause of disease in clinically affected cats, nor to draw any firm conclusions as to the nature of the defect within the breed as a whole. While the clinical significance of these findings therefore remains unclear, it seems appropriate to suggest that evidence of elevated kidney enzymes in an otherwise healthy Birman cat should not be over interpreted as evidence of severe or progressive disease. It would however, seem sensible to monitor affected cats, and to consider the possibility of renal dysfunction when undertaking anaesthesia, surgery or treatment in cats of this breed.
Acknowledgements: I would like to thank all of the owners who volunteered their cats for the survey, the Southern and South Western Birman Cat Club for their assistance, the veterinary surgeons who referred cases or sent blood samples, and members of the University of Bristol who helped in this study.
Table 1. Long term serum urea and creatinine levels in two healthy Birman cats.
Normal adult range: Urea 6.5-10.5 mmol/l Creatinine 80-150 mmol/l
Table 2. Long term results for an individual family of Birman cats.
Normal range: Urea 6.5-10.5 mmol//l Creatinine 2-5 months of age: 35- 88 mmol/l Adult: 80-150 mmol/l
Dr. Daničlle Gunn-Moore, Email: Danielle.Gunn-Moore@ed.ac.uk Tel: 0131 650 7650 Fax: 0131 650 7652
Important Note Please make sure to ask your vet to place your Birman cat on a drip before, during and after any type of surgery where an anesthetic is used. This enables the anesthetic to be flushed out through the system very rapidly and aids rapid recovery.
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KIDNEY FUNCTION IN BIRMAN CATS: WHAT DO WE KNOW AND WHAT CAN WE FIND OUT? By Dr Rebecca Richards MA, VetMB, PhD, CertSAM, MRCVS © Copyright The contents of this paper may only be reproduced with the permission from: The Southern & South Western Birman Cat Club, Dr Rebecca Richards or Dr Danielle Gunn-Moore.
Introduction The Birman is the fourth most popular feline pedigree breed in the UK, with over 4000 kittens being registered annually with the Governing Council of the Cat Fancy. It is very fortunate in having a well-organized and educated breed society, the Southern and South Western Birman Cat Club. The breed society has access to a database including the pedigree information of over 90,000 cats. This has allowed calculation of the coefficients of inbreeding to be made, for Queens and offspring in the Birman population today. These data indicate a population with a degree of inbreeding steadily rising over the past 30 years to reach levels of between 40 and 60% in some cases as shown in Fig 1.
Fig 1 Coefficients of inbreeding in the Birman breed In breeding of this level is expected in a pedigree population, and is in line with other pedigree dog and cat breeds. In fact the degree is less than in some. However in all animal and human populations in breeding can create problems with harmful traits being inherited along with the good. In the cat world the Siamese is known to have an inherited problem causing a blockage of part of the stomach, the Persian has an inherited defect of the walls of blood vessels and some of the British short hairs have blood clotting problems. Unfortunately the beautiful Birman is not immune and conditions, which may have an inherited component, include a liver shunt and kidney dysfunction. The problem of kidney function in Birmans is discussed below; as will become obvious from the information this problem is no ones fault. Potential kidney problems are widespread, and therefore the work myself and Dr Danielle Gunn-Moore will undertake is not designed to hunt out culprits or specific lines but to help the health of the breed as a whole. Preliminary work by Dr Danielle Gunn-Moore in 1997 indicated that measures of serum and Createnine (a standard measure of renal function used in general practice) in Birmans may be elevated above those expected in a normal cat population and that this may have an inherited component. In a prospective study involving 119 Birman cats from over 20 different households significantly elevated serum createnine levels was found. This appeared to be age related with 80% of Birmans of less than 6 months of age having createnine levels above the normal range for that age, while 30% of adults appeared to be similarly affected. Birmans with elevated createnine were followed up over an 18-month period and a spectrum of kidney related problems were observed. Createnine levels remained elevated but were stable in the majority of cats but 4 cats progressed to renal failure (un-related to surgery) in this time. In two families of related cats 2 out of 4 and 3 out of 4 cats progressed to terminal renal failure after routine neutering. In addition collected data on the cause of death in Birmans showed that out of 92 cases so far, 19 died of renal failure, 8 of these were under 10 years of age. We can therefore see that there is a kidney problem within the breed, which may have an inherited cause. This should not panic us but we should consider what we could do for the Birman cat in the light of what we know. A consideration before any study is entered into is to make your veterinary surgeons aware of the potential hazard lurking when a Birman is anaesthetised and ask for Kidney blood tests to be performed prior to any surgery. Further to this you could consider helping with a scientific study constructed by myself and Danielle, our aim is to discover the cause of renal dysfunction in Birmans and provide practical suggestions on how to deal with it. We are in the process of applying for a grant for this work so the costs to cat owners will be minimal. The study. Aims: 1. To investigate the prevalence of raised renal parameters in Birman cats. 2. To investigate the significance of these in renal disease in the Birman. 3. To investigate the mode of inheritance and genetic cause of increased renal parameters in Birman cats. Details: The construction of the study falls into 3 parts. Collection of serum and urine data from Birmans presented for neutering. Breeders will issue new owners with an information sheet for their veterinary surgeon, detailing what is known about Birman renal function and its relevance to anaesthesia. This sheet will be produced in collaboration with club members therefore not alarming perspective new "parents" Veterinary surgeons will be asked to take blood samples for haematological and biochemical investigations and urine by for urine analysis and culture. All cats will have been starved for surgery negating the effect of feeding on serum urea levels. All samples will be sent to the Royal Veterinary College Dept of Pathology for analysis. A sample of blood from all cats sampled will be reserved for later DNA analysis. Any cats with raised BUN and Createnine levels will be monitored at 4 monthly intervals. Full serum biochemical and haematological investigations will be repeated combined with urine analysis and culture. Controls for this part of the study will be provided by comparison of data for age matched normals at this laboratory. Collection of kidney tissue for histology and electron microscopy. A Birman Kidney donor card will be designed; this will be registered with veterinary surgeons taking decision making away from tragic circumstances and allowing valuable breed information to be gathered. This will allow the removal of kidneys from Birmans, which have been euthanased for any reason. The card will detail storage instructions for the vet and details of where to send the tissue. The samples will be submitted, for histological and electron microscopic investigation. Comparison of kidneys from Birmans, which were euthanased due to renal failure following persistently elevated urea and createnine and those, which were euthanased for other reasons will be made. Genetic analysis. The existing computerised 30,000 cat data base will be used. Initially the pedigrees of known affected cats will be annotated for affected and common ancestors to establish a likely mode of inheritance. This will allow a relevant type of DNA analysis to be performed on the stored blood samples. The DNA analysis will be completed by geneticists linked to the Feline Advisory Bureau Feline genome project.
What will all this tell us? Examination of serum BUN and Createnine data will investigate the prevalence of this problem in the Birman breed, in the absence of other clinical problems. Follow up blood samples in conjunction with urine analysis will allow investigation of the relevance of raised renal parameters in the progression of renal failure in the Birman cat. Data from histological examination of kidneys will indicate the likely mechanism of renal failure and persistently raised urea and createnine. Combined these data may suggest likely treatments and veterinary management. Examination of pedigrees may elicit the likely mode of inheritance in this breed, and suggest breeding strategies to breeders to both decrease the amount of inbreeding and produce healthier Birmans. DNA analysis should give rise to the likely genetic defect involved in this condition and add to the current Feline Advisory Bureau Feline Genome Project.
UNFORTUNATELY THIS PROJECT DID NOT CONTINUE DUE TO
LACK OF
FUNDS.
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