We are delighted to announce that we have identified a second genetic mutation in Doberman pinschers with dilated cardiomyopathy (DCM) and have a new test available!
We have discovered that there are two mutations that can lead to Doberman pinscher dilated cardiomyopathy, PDK4 (NCSU DCM1) and the newly discovered NCSU DCM2. Although both PDK4 (DCM1) and DCM2 can each independently lead to the development of the disease, the risk is highest when a dog is unlucky enough to have both mutations.
We now recommend that Doberman pinschers be tested for both mutations. To order a test for this disease,click here.
About Doberman pinscher DCM
Doberman pinschers are one of the most common breeds of dogs to be affected with Dilated Cardiomyopathy (DCM). When a Doberman pinscher is diagnosed with DCM, the implication of subsequent abnormalities, such as congestive heart failure and sudden death become concerns.
We have previously demonstrated that dilated cardiomyopathy is an inherited disease in the Doberman pinscher and appears to be inherited in an autosomal dominant fashion. We previously identified one genetic mutation (PDK4; NCSU DCM1) for the disease and have now identified a second, NCSU DCM2. Dogs that carry both mutations are at the highest risk of getting sick from the disease, although dogs with a mutation in either gene can develop the disease as well.
About Doberman pinscher DCM
Doberman pinschers are one of the most common breeds of dogs to be affected with Dilated Cardiomyopathy (DCM). When a Doberman is diagnosed with DCM, the implication of subsequent abnormalities, such as congestive heart failure and sudden death becomes concerns. We have previously demonstrated that dilated cardiomyopathy is an inherited disease in the Doberman pinscher and appears to be inherited in an autosomal dominant fashion. We have identified one genetic mutation for the disease that we can test for, a mutation in the PDK4 gene. However, we know that in human beings there are more than 20 different mutations that can all cause this disease and that Dobermans likely have more than one.
Can you help us identify a second mutation? We are currently looking for DNA samples from Doberman pinschers with dilated cardiomyopathy or a cardiac arrhythmia who are negative for the PDK4 gene. If you have an affected dog but do not know its genetic status and can send us the clinical information we can do the genetic test for you.
1Faculty of Medicine and Health Sciences, School of Veterinary Medicine and Science, The University of Nottingham, Sutton Bonington Campus, Loughborough LE12 5RD, UK 2Department of Pharmacology, Weill Cornell Medical College, 1300 York Avenue, New York, NY 10065, USA
Cardiovascular disease is a leading cause of death in both humans and dogs. Dilated cardiomyopathy (DCM) accounts for a large number of these cases, reported to be the third most common form of cardiac disease in humans and the second most common in dogs. In human studies of DCM there are more than 50 genetic loci associated with the disease. Despite canine DCM having similar disease progression to human DCM studies into the genetic basis of canine DCM lag far behind those of human DCM. In this review the aetiology, epidemiology, and clinical characteristics of canine DCM are examined, along with highlighting possible different subtypes of canine DCM and their potential relevance to human DCM. Finally the current position of genetic research into canine and human DCM, including the genetic loci, is identified and the reasons many studies may have failed to find a genetic association with canine DCM are reviewed.
1. Dilated Cardiomyopathy Aetiology and Epidemiology
Cardiovascular disease is the fourth most common cause of death in dogs  and one of the most common causes of death in humans . Dilated cardiomyopathy (DCM) is the second most prevalent form of heart disease in dogs, accounting for 10% of cardiac diagnoses , and is estimated to be the third most common inherited type of heart disease in humans, reported to affect 35.6 in 100,000 people, although this is thought to be an underestimation [4, 5].
Due to the similar nature of DCM in humans and dogs in terms of disease phenotype and progression, it has been suggested that canine DCM can act as a model for human DCM . Conversely, knowledge obtained from the clinical management of people with DCM may guide improvements in the clinical care and outcomes of companion animals with DCM.
Animal models of DCM are useful in providing insights into the molecular and cellular progression of the disease and thus lead to potential new treatments . While there are many animal models where DCM is induced, for example [8–11], naturally occurring cases of canine DCM are also valuable, in particular with regard to natural disease progression, especially where the underlying cause can be shown to be similar in dogs and people (e.g., similar genetic function) . In addition to providing a potential natural model for human DCM, canine cardiovascular health is an important issue in its own right. Understanding the disorder will impact veterinary care, treatment, and prognosis and may also influence pedigree breeding, health, and welfare. Here we review the clinically distinct types of canine DCM and relate these to clinical heterogeneity seen in human DCM. Furthermore we provide a review of the known genetic contributions to DCM and discuss how these factors may inform future clinical management and breeding strategies in the dog.
2. Clinical Characteristics of DCM
DCM is characterised by cardiac ventricular chamber enlargement and systolic dysfunction which often leads to congestive heart failure and death . The aetiology of DCM is complex in that genetic factors, myocardial ischemia, hypertension, toxins, infections, and metabolic defects have been implicated in human disease . Both human and canine DCM have a number of phases of progression starting with a long asymptomatic period before clinical signs appear [6, 15]. During this asymptomatic period, no functional changes in cardiac tissue have yet been reported, but it is possible that the underlying causes (e.g., genetic factors, toxins, and infections) are already initiating the disease . During the next stage, there are again no reported outward clinical signs and the individual usually appears to be healthy, but cardiovascular electrical and morphological changes can be observed [6, 15–17]. Cardiovascular electrical changes may be detected using Holter monitoring for 24 hours, with individuals that go on to develop canine DCM often displaying ventricular arrhythmias . Echocardiography can identify individuals that have an enlarged left ventricle which ultimately leads to symptomatic canine DCM . Due to the apparently asymptomatic nature of this stage it is often termed the occult or preclinical stage and can last for several years in dogs [6, 17, 18]. In the final stage of DCM patients present with clinical signs of heart failure, commonly including cough, depression, dyspnoea, weight loss, and syncope, the individual requires treatment for heart failure, but prognosis is often poor [6, 19]. In humans, mortality 10 years following diagnosis is roughly 40%, although there is a wide variation with some individuals remaining asymptomatic, conversely many individuals suffer from sudden death . Dogs also have significantly shortened lifespan following diagnosis, mean survival time following diagnosis, usually at the point of developing overt clinical symptoms, being 34 weeks, although, similar to humans, large variations are observed, with some surviving for several months while others only live for a few weeks [21–23].
Treatment of DCM in humans is aimed at minimising the effect of heart failure on the patient and delaying disease progression . Standard medical treatment for human DCM consists of ACE inhibitors and β-blockade, often with a diuretic agent and, in the latter stages of disease progression, inotropic agents are frequently prescribed [24, 25]. Heart transplants are often the last resort in treating human heart disease; however the proportion of heart transplants in humans due to nonischemic cardiomyopathy, of which DCM is the second most common form, has increased to become the leading cause of heart transplant in recent years: 51% of transplant cases had nonischemic cardiomyopathy . Canine DCM is treated in a similar manner to human DCM, in that treatment is aimed at minimising the effect of heart failure . This treatment usually consists of diuretics, ACE inhibitors, positive inotropes, and other vasodilators [27, 28]. There is evidence that treatment when preclinical symptoms appear can increase lifespan, but this requires screening of individuals for preclinical DCM . Heart transplants and other cardiac assist devices are not generally available to canine DCM patients.
2.1. Evidence for Different Types of Canine DCM
Although dogs within all breeds have the potential to develop DCM, there are some breeds that are particularly afflicted by DCM . These include Newfoundlands, St. Bernards, Doberman Pinschers, Great Danes, Irish Wolfhounds, Boxers, and English Cocker Spaniels . While these breeds, as well as other less frequently affected breeds, can be diagnosed as having DCM, there is evidence that different breeds may present with distinct types of DCM. This evidence consists of differential survival times from diagnosis, histopathology, inheritance patterns, and age of onset [21, 31–35].
Within canine DCM, two distinct types of histopathological variations have been described: “attenuated wavy fibre type” and “fatty infiltration type” . While this evidence may be subjective, it adds to the evidence suggesting that there are different types of canine DCM. The fatty infiltration type is less subjective and has only been reported in Doberman Pinschers, Estrela Mountain Dogs, Great Danes, and Boxers [32, 36–38]; while the wavy fibre type is more ubiquitous, it does not seem to be restricted to specific breeds and can also occur in breeds which display the fatty infiltration type [32, 37]. As the wavy fibre type is found across breeds and in many individuals, it could be the tissue’s response to the other processes of DCM. In particular atrophy, or attenuation, of muscle fibres is a frequent result of processes that prevent normal contractile ability: contractile ability is consistently compromised in DCM . The prevalence and clinical significance of these histopathological variants remain to be established, although the phenotype can only be established post mortem and thus is unlikely to be useful in a clinical setting.
Human DCM is generally inherited in an autosomal dominant fashion , but autosomal recessive, X-linked recessive, and mitochondrial modes of inheritance have all been reported . In common with human inheritance patterns there are several types of inheritance suggested in canine DCM. These include autosomal recessive , X-linked , and the common autosomal dominant inheritance [35, 38]; although often with reduced penetrance, not all dogs with the DCM genotype will develop the disease [41, 42]. X-linked and autosomal inheritance patterns show that the genetic basis of the disease is different. Recessive and dominant inheritance patterns also suggest the presence of different mutations leading to DCM and reduced penetrance indicates that there are likely to be additional factors involved in the formation of the disease phenotype. These additional factors may involve additional genes, epigenetic effects, and environmental effects including, but not limited to, diet, exercise, stress and toxins, or a combination of any number of these.
There is a wide variation in the long term prognosis of canine DCM. Some dogs, with appropriate disease management, can have a good quality of life for many years following a DCM diagnosis, whereas others die within weeks despite medical intervention [21–23]. Within this variation there are prognosis trends within breeds. Doberman Pinschers are a breed with particularly poor prognosis, and mean time to death (from diagnosis) is in the range of 7.4 to 9.7 weeks [21, 31], while the mean time for other breeds is reported to be about four times that at 34 weeks . Great Danes also suffer from a poor prognosis with Martin et al.  finding that they have the lowest median survival time of breeds included in their analysis, while Doberman Pinschers had the lowest upper quartile range.
Age of onset can also affect prognosis. There is a juvenile form of DCM in Portuguese water dogs, where age of onset is measured in weeks from birth [43, 44], while in most other cases age of onset is measured in years . It would seem from this that DCM in Portuguese water dogs is a distinct condition. Even within adult canine DCM there is variation between breeds as to when individuals present with outward clinical signs. For example, Great Dane mean age of onset is 4.8 (SD ± 2.3) years , which is comparable to Irish Wolfhound mean age of onset of 4.40 (SD ± 2.03) years ; however, Doberman Pinscher’s mean age of onset is in 7.3 years in males and 8.6 years in females . This variation in mean age of onset could further suggest that there are different types of canine DCM.
There also appears to be different types of human DCM, with different inheritance patterns and age of onset reported . If canine DCM can be appropriately matched to human DCM in terms of age of onset, inheritance pattern, survival time, and histopathology, they could provide appropriate models for each other. In particular some cases of childhood DCM have been shown to have an autosomal recessive pattern of inheritance , and in this instance the juvenile DCM observed in Portuguese water dogs  could be an appropriate model. There are currently several types of DCM identified in humans , but additional studies of canine DCM phenotypes are required to allow appropriate matching of canine and human DCM categories. Once identified, knowledge about canine DCM types could benefit current and future potential treatments and support for both human and canine DCM patients, in addition to elucidating other clinically important factors in canine DCM, such as longevity and prognosis.
2.2. Genomic Research of DCM in Humans
While there are many implicated causes or risk factors related to developing DCM and disease progression, genetics is a common one, with the disease often affecting several individuals within a family. To date mutations in over 50 genes have been associated with DCM in humans; however mutations in the most prevalent DCM related genes only account for approximately 50% of patients with DCM . Genetic testing of individuals related to DCM patients can allow those that are at high risk of developing DCM to be more closely monitored . This genetic testing is carried out on a panel of about 50 loci and more than one locus can be implicated in the disease  suggesting a dose effect, whereby the more DCM alleles an individual carries, the more severe the phenotype . Gene penetrance has also been reported to affect disease expression and severity, and likewise the type of mutation and the specific gene which is affected often lead to differing features, age of onset or severity, and prognosis [49, 50].
Human DCM-associated genes identified to date are involved in a range of functions but can usually be placed into one of six functional groups: sarcomeric protein genes, cytoskeletal protein genes, nuclear envelope protein, desmosomal protein genes, calcium/sodium-handling genes, and transcription factor genes . Cardiac muscle consists of striated muscle, and the sarcomere is the smallest unit of contractile muscle within this and thus alterations to this could lead to heart disease . The cytoskeleton forms the majority of the cytoplasm, enabling cells to maintain their shape and facilitating communication within the cell [52, 53]. The nuclear envelope provides a barrier between nucleic acid synthesis and the rest of the cell but must remain permeable to allow the cell to function , a large number of proteins within the nuclear envelope have been implicated in chromatin organization and gene regulation . The desmosome provides mechanical strength to tissues and potentially has cell signalling capacity, both of which are essential for cardiac function . Na+/Ca2+ are important in the contraction of muscle  and as such calcium/sodium-handling genes are important in maintaining the correct concentration of Na+/Ca2+ for contraction of the heart. Transcription factors regulate the rate at which transcription of DNA to mRNA occurs; this rate is important in controlling the expression of genes and therefore the amount of a protein produced . The breakdown of any of these functions has the capacity to lead to disease, including DCM. Table 1 shows the genes with mutations associated with DCM in humans, including the group into which the gene falls (where appropriate).
Table 1: Genes with mutations associated with DCM in humans.
2.3. Genetics of Canine DCM
Canine DCM has often been used as a model for human DCM, but it is also a major clinical challenge in companion animals [3, 18, 22, 59]. It is has been established that, in common with human DCM, canine DCM frequently has a familial basis [33–35, 42]. Despite this, current understanding of the genetics of canine DCM is limited, in particular compared to the depth of genetic information available for human DCM. Indeed it is only recently that any loci have been associated with canine DCM [6, 60–62]. Genes associated with canine DCM are DMD in German short-haired pointers , PDK4 in Doberman Pinschers , and STRN in Boxers , in addition to a locus on chromosome 5 in Doberman Pinschers . Additional polymorphisms on chromosomes 1, 10, 15, 17, 21, and 37 have also been implicated in Irish Wolfhounds . There are two methods that have been employed in attempts to identify genes associated with canine DCM, candidate gene studies, and genome wide association studies (GWAS).
3. Canine Candidate Gene Studies
Candidate gene studies for canine DCM primarily involve examining genes with variants associated with human DCM or associated conditions, for example [64–69]. The majority of canine DCM genetic studies have been of this type; however, only one mutation associated with canine DCM has been identified in this manner, which is that of a deletion in the Striatin gene in Boxers, a gene previously associated with Boxer arrhythmogenic right ventricular cardiomyopathy using GWAS . All other candidate gene studies have failed to find an association with canine DCM in the cohort examined (see Table 2), and unfortunately the small sample sizes frequently utilised could have limited the power to detect an association. In addition to small sample sizes in a number of studies, control (non-DCM cases) dogs have been limited or have not been appropriate (see Table 2 for exact numbers). Suitable controls should be breed matched and over a certain age to ensure that they are unlikely to develop DCM. Table 2 shows the genes examined for mutations associated with canine DCM in a variety of breeds, sample sizes, and control dogs, in the published literature to date.
Table 2: All genes investigated in relation to canine DCM.
4. Genome Wide Association Studies (GWAS)
Genome wide association studies are a method of screening the genomes of many individuals for variants or regions that are associated with a trait . Some variants will fall within genes and some outside of genes. When variants associated with a trait are found outside of genes it can be more difficult to establish their mode of action.
There have been three GWAS looking for an association with canine DCM. One of these led to the identification of a deletion in a splice site of PDK4 associated with DCM in Doberman Pinschers . A separate GWAS in Doberman Pinschers revealed a single SNP associated with DCM in a different location to the PDK4 gene . The only other GWAS undertaken with regard to canine DCM is that by Philipp et al.  which found one significantly associated SNP and five suggestively associated SNPs in Irish Wolfhounds. Of all the loci identified as associated with canine DCM only two are on the same chromosome, one of the Irish Wolfhound SNPs and the Striatin genes are both on chromosome 17, but even these are far apart. This indicates that there may be many loci involved in the development of canine DCM.
5. The Effects of Multiple Loci on DCM
Thus far in both canine and human genetic DCM studies loci have only been considered for an association with disease individually. There have been indications that multiple loci may influence the development of DCM . In human DCM where a pannel of more than 50 loci are tested concurrently, often several loci are implicated. Simpson et al.  have shown theoretically that multiple loci affect the development of DCM in Doberman Pinschers. While this still requires valiadation, it is possible that similar effects occur in other breeds and species.
6. Power to Detect an Association with Canine DCM
The majority of studies undertaken with the aim of identifying causal genetic variants of canine DCM have only utilised small samples (5–40 individuals) which is unlikely to be large enough to detect an effect. To establish appropriate study sizes and indicate the effect size that can be detected in published studies Power 3.1.7 Chi-squared goodness of fit tests were used (using the methods from ). This takes known input parameters, including sample size, and calculates estimated effect sizes based on assumed power and can be used to indicate minimum sample size for prescribed power, alpha error rate, and effect size. This was done to indicate minimum sample sizes needed to detect various effect sizes (Figure 1).
Figure 1: goodness of fit tests: contingency tables Df = 1, err prob = 0.05, and power ( err prob) = 0.8.
Published studies that have identified genetic variants associated with DCM have used sample sizes of 180 , 132 , and 49 . Assuming these studies had enough power to identify a positive effect (0.8), the effect sizes of these variants in these studies are 0.2088, 0.2438, and 0.4002, respectively, calculated using the sensitivity power analysis in Power 3.1.7 . These effect sizes, while not large, are larger than the standard effect size for small effect of 0.1. None of these variants explain all incidences of DCM, suggesting that other factors, which may be additional genetic variants of smaller effect, are involved. The sample size required to obtain a positive result from variants with small effect size (0.1) is 785, a number possibly not obtainable for all breeds but could be aimed for in future studies. It is likely that earlier studies concentrated on simple Mendelian recessive, dominant traits and even a multiplicative risk models where Karlsson & Lindblad-Toh  had suggested that affected and control groups of 20, 50, and 100, respectively, may suffice. Despite these suggestions, the authors indicated that higher group sizes (around 500 samples) would likely provide sufficient power to map an allele conferring a two-fold risk.
6.1. Discussion of Selected Breeds
While there are many breeds affected by canine DCM only a few have had genetic loci identified as associated with the disease. Here we discuss breeds with adolescent and adult onset DCM associated loci. The juvenile DCM that Portuguese water dogs develop is not discussed because it is already considered to be a distinct condition .
6.2. Boxers: Striatin (STRN)
The Boxer breed of dog was developed in the late 1800’s primarily from the now extinct hunting dog the Bullenbeisser . As with the development of most modern breeds there is documented evidence of inbreeding to produce the desired characteristics. In the case of the boxer this included a mating of a son to his mother, and following the creation of a breed standard in 1902 it is likely that usually Boxers will have exclusively been mated to other Boxers . This limited genetic diversity is likely to have led to Boxers being prone to developing a number of diseases including heart disease, of which they frequently develop both arrhythmogenic right ventricular cardiomyopathy (ARVC) and DCM . Since boxer cardiomyopathy was described by Harpster  there have been several subtypes described, of the two displaying overt clinical symptoms these most closely align to human ARVC and DCM . Recently Meurs et al.  tested a deletion in the striatin (STRN) gene for an association with DCM in boxers. This deletion has previously been associated with ARVC and it was hypothesised that ARVC and DCM are variants of the same disease in Boxers and the homozygous genotype leads to DCM rather than ARVC . They found a significant association with the deletion in its homozygous form and DCM, but there were three cases of DCM where there was no deletion in the gene, thus indicating that there is at least one more cause of DCM in the breed to be established .
6.3. Doberman Pinschers: PDK4 and Chromosome 5 SNP
The Doberman Pinscher breed was developed at the end of the 1800’s in Germany  when a number of individuals from established breeds were used to improve various characteristics. According to Gruenig  these include the Manchester terrier, Greyhound, Rottweiler, Gordon Setter, Old English Sheepdog, Beauceron, Pinscher (probably German Pinscher), Weimaraner, and other less specific breeds such as Mastiff (possibly Great Dane), Hound, and Sporting dogs. The development of the breed happened rapidly, over a period of about 30 years, and since then Doberman Pinschers have only been bred to Doberman Pinschers , leading to a closed gene pool. Although a number of breeds contributed to the Doberman Pinscher it is likely that relatively few individuals of each breed were used likely leading to low genetic diversity. In addition to relatively few founders there is evidence of some individuals contributing a greater number of offspring to the breeding population than others .
Doberman Pinschers can develop a particularly severe type of DCM with rapid disease progression following the diagnosis of DCM with mean survival time of less than 10 weeks [21, 31]. Poor survival time following diagnosis combined with the high prevalence of the disease with estimates ranging from 45% to 63% means DCM in this breed is a particular problem for clinicians . Doberman Pinschers display the fatty infiltration type of histopathology . Despite these poor statistics, age of onset of clinical signs is often later than in other commonly affected breeds (7.3 years in males and 8.6 years in females, compared to 4.8 (SD ± 2.3) years in Great Danes), giving individuals a good quality of life up until overt DCM clinical signs [31, 77]. Across age groups there is no difference in clinical signs associated with DCM between the sexes including echocardiographic changes, presence and number of ventricular premature contractions, and overt DCM . Unfortunately, however, males are more likely to have overt DCM than females with 73.7% of all observed males becoming clinically overt while only 26.3% of females observed became clinically overt .
DCM in Doberman Pinschers appears to be inherited in an autosomal dominant fashion with equal numbers of males and females affected, male-male transmission, and the mating of two affected individuals producing unaffected offspring . There have been two loci identified as associated with DCM in the breed, a deletion of a splice site in pyruvate dehydrogenase kinase, isozyme 4 (PDK4), and a SNP on chromosome 5 [6, 60]. Unfortunately neither of these loci explains all incidences of DCM, and the PDK4 deletion is not significantly associated with DCM in a separate Doberman Pinscher population . There are still additional causes of DCM to be identified in Doberman Pinschers and the function of the SNP on chromosome 5 needs to be established.
6.4. German Short-Haired Pointers: Dystrophin (DMD)
The only gene associated with canine DCM in German short-haired pointers is Dystrophin (DMD) . German short-haired pointers are not considered a breed particularly afflicted by heart disease and the deletion was only identified in two male litter mates [3, 63]. This could be an isolated case which is unlikely to have implications in other breeds, particularly as the affected individuals also had skeletal myopathies, whereas in most cases of canine DCM there are not any other myopathies present .
6.5. Irish Wolfhounds
Although Irish Wolfhounds have a long history, this includes a period when they were close to extinction. As part of conserving the breed, Great Danes, Scottish deerhounds, Borzoi, and Mastiffs were crossed with the few remaining Irish Wolfhounds [61, 79]. While this will have introduced some degree of genetic diversity to the breed, by necessity a large amount of inbreeding will have been required to retain the Irish Wolfhound phenotype and so, like most modern breeds, genetic diversity is low .
Irish Wolfhounds do not usually develop a particularly severe form of DCM and with appropriate management can live with the disease for many months or years . Unfortunately, however, the prevalence of heart disease, including DCM, within the breed is very high, with 41% of individuals presenting with cardiac abnormalities, of which 58% have DCM . This high prevalence combined with early onset of clinical signs at around 4 years old  means that DCM in Irish Wolfhounds is of concern and so identifying genetic causes of the disease could have a large impact on the health of breed.
The mode of inheritance of DCM in Irish Wolfhounds has been shown to be autosomal dominant major gene effect, but with reduced penetrance indicating that multiple factors influence disease progression . Of the six SNPs associated with DCM in Irish Wolfhounds to date, only three lie within known genes . Further work is therefore required to establish the functional significance of the alleles and to confirm the associations with DCM.
7. Conclusions: Impact of Genetics on Canine DCM
In the short term, the identification of the genetic contributors to DCM will enable targeted heart monitoring prior to the onset of clinical signs and clinical management of those dogs with increased risk of developing DCM. In the longer term, knowledge of the genetic factors which predispose to DCM will allow for selective breeding strategies to be considered and may identify novel therapeutic and diagnostic approaches. Individuals likely to develop DCM, identified through robust genetics, could be removed from breeding programmes with the ultimate goal of reducing the number of affected animals within the population and promoting the long term welfare of the breed. Understanding the genetic causes may also aid the stratification of distinct clinical subtypes of DCM. This knowledge may also permit the development of novel DCM management programmes, help to guide prognosis, and assist with future drug and intervention research. Furthermore, investigations into causative genes in canine DCM may prove beneficial for other species, including humans. Novel mutations in canine breeds may serve as candidate genes in affected humans. For these reasons a more detailed understanding of the genetic basis of DCM in diverse dog breeds is now required.
Conflict of Interests
The authors declare that there is no conflict of interests regarding the publication of this paper.
The authors gratefully acknowledge generous funding from the BBSRC University of Nottingham Doctoral Training Programme BB/J014508/1 and the School of Veterinary Medicine and Science and, in part, by an unrestricted educational research grant provided by Boehringer Ingelheim Vetmedica, all to Catrin S. Rutland, Nigel P. Mongan, and Malcolm Cobb.
180. The Role of the Pyruvate Dehydrogenase Kinase 4 (PDK4) Gene Mutation in the Development of Dilated Cardiomyopathy in Dobermanpinschers and Potential Application of Cardiac Gene Therapy
Dilated cardiomyopathy (DCM) is estimated to be the third most common inherited type of heart disease in humans reported to affect 35.6 and 0.57 in 100,000 adults and children, respectively. The Doberman Pinscher (DP) is a canine breed affected with idiopathic, non-ischemic DCM that closely resembles the human counterpart acting as a clinically relevant human model. Recently, a 16 base pair deletion in the 5’ donor splice site of intron 10 of the pyruvate dehydrogenase kinase 4 (PDK4) gene, encoding for a mitochondrial protein involved in energy metabolism, has been identified but the relationship between the PDK4 mutation, mitochondrial function and phenotypic development of DCM is largely unknown. Our research has focused on understanding the relationship between the consequences of the PDK4 mutation on mitochondrial function and phenotypic development of DCM as well as the potential of cardiac gene therapy to correct the phenotype. A total of 64 DP were tested for the PDK4 mutation and screened for DCM. Healthy dogs and dogs diagnosed with DCM were further divided into 3 groups based on the presence of the genetic mutation: Wild-type (PDK4wt/wt), Heterozygous (PDK4wt/del), and Homozygous (PDK4del/del). Preliminary analyses using isolated mitochondria from skin fibroblasts of these dogs demonstrated a lack of detectable PDK4 protein expression in PDK4del/del, and a significant decrease in PDK4wt/del (48% of normal). Phase contrast microscopy and immunofluorescence studies revealed significantly different morpho-phenotypic characteristics and reduced capacity to adapt to unfavorable metabolic conditions as compared to healthy dogs. Assessment of mitochondrial metabolic potential and function (oxygen consumption rate (OCR) and extracellular acidification rate (ECAR)) were performed using an extracellular flux analyzer. Cells were stressed using serum glucose starvation. Compared to healthy dogs, PDK4wt/del and PDK4del/del revealed a much lower basal respiration rate (OCR reduction of 46% and 68% of normal, respectively) and decreased metabolic potential to meet energy demands (85% and 72% of normal, respectively). Maximal mitochondrial respiration and spare respiratory capacity were all significantly lower in the affected dogs (PDK4wt/del 42% and 14%, and PDK4del/del 40% and 1.4% of normal OCR, respectively). Our results indicate that the mitochondria of affected dogs have a lower metabolic capacity and thus exhaust the two major energy-producing pathways, aerobic and glycolytic metabolism, at a much faster rate when under stress compared to healthy control dogs. Although we detected a significant decrease in PDK4 protein levels, PDK4 transcription levels have yet to be determined in these samples. Our immediate future goals include 1) quantitative PCR to compare PDK4 transcript levels, 2) PCR and sequencing to identify abnormalities in PDK4 mRNA splicing in affected dogs, 3) assessments of mitochondria ATP production and PDK4 protein kinase function. Our long-term goal is to perform in vitro experiments to assess if mitochondrial abnormalities can be improved with gene therapy. To this end, we have cloned canine healthy PDK4 into an adeno-associated virus construct. Ultimately, our efforts will lead us to a cardiac gene therapy clinical trial for Doberman PDK4-DCM.
Here are some important health issues you need to know. All though there aren't test for each, and even with testing there is no way to know for sure your puppy wont developone of these health problems.
These health conditions have been identified in the Doberman Pinscher. Items marked with asterisks (***) can be identified through testing. Screening tests are not currently available for the other conditions listed. It is important to know the status before breeding a dog or bitch - clinically affected dogs, dogs exhibiting symptoms for any of these conditions should NOT be bred.
The text below is intended as an aid to those seeking health information and should not be used to form a diagnosis replacing regular veterinary care by one's own Veterinarian.
CARDIOMYOPATHY - is suspected to be an inherited disease in Dobermans. Research is in progress in several institutions. An echocardiogram of the heart will confirm the disease but WILL NOT guarantee that the disease will not develop in the future. A 24 hour holter will record Premature Ventricular Contractions (PVCs. Drs Meurs' and Estrada's Cardiomyopathy presentations at the 2010 National can be viewed online at UStream. Click here for details
*** HIP DYSPLASIA - is inherited. It may vary from slightly poor conformation to malformation of the hip joint allowing complete luxation of the femoral head. Both parents' hips should be Orthopedic Foundation for Animals (OFA) certified - excellent, good or fair rating. There are other hip labs that are qualified to certify hips. Click here for more info.
*** HYPOTHYROIDISM - is probably inherited and means that the thyroid gland is not producing enough hormone to adequately maintain the dog's metabolism. It is easily treated with thyroid replacement pills on a daily basis. Thyroid testing (T3, T4, TSH and autoantibodies) should be performed on an annual schedule. Finding autoantibodies to thyroglobulin (T4 autoantibodies) is an indication that the dog has "Hashimoto's Disease". Low thyroid dogs, manifested by a high TSH and a low T4, should be treated and monitored on a regular basis.
*** vWd (VON WILLEBRAND'S DISEASE) - is an autosomally (not sex linked) inherited bleeding disorder with a prolonged bleeding time and a mild to severe factor IX deficiency. Von Willebrand's factor antigens of 70% 180% are considered to be within the normal range for Dobermans. When dogs are tested through the Elisa assay blood test for vWD, they are tested for carrier status only NOT the disease. It is believed that carrier status tests (Elisa assay) are inaccurate if a dog is ill, received any medication or vaccination within 14 days of testing, pregnancy, bitches in heat or lactation. Stress conditions (infections, parasites, hormonal changes, trauma, surgery, emotional upset, etc.) may have an effect on the outcome of the vWD blood test and might be a contributing factor for bleeding tendencies. vWD carrier status is quite common in Dobermans. A DNA test for vWD is now available - genetically: clear, carrier (inherited one disease gene), affected (inherited two disease genes) - results are not effected by stress conditions, etc. Learn about DNA labs here.
WOBBLER'S SYNDROME - is suspected to be an inherited condition in Dobermans. Dogs suffer from spinal cord compression caused by cervical vertebral instability or from a malformed spinal canal. Extreme symptoms are paralysis of the limbs (front, hind or all 4). Neck pain with extension and flexion may or may not be present. Surgical therapy is hotly debated and in some surgically treated cases, clinical recurrence has been identified.
*** PRA (PROGRESSIVE RETINAL ATROPHY) - is an inherited condition in Dobermans. Clinically, visual acuity is diminished, first at dusk, later in daylight. The disease progresses over months or years, to complete blindness. A screening test is available and can be performed by a veterinary ophthalmologist. CERF (Canine Eye Registration Foundation) will certify eyes for 12 months from the date of evaluation.
We do our best to only breed the healthiest Dobermans, trying to ensure the best health for our puppies, BUT Note DCM is a killer of the Breed. All the health testing can be done with no signs of the disease BUT the dogs can die from it.
This is just information for you the public..
I want you to know vWD can be bred out of our breed in 3 generations if breeders would just health test and breed accordningly.
We are not supposed to be throwing the baby out with the bath water, but the following can happen if 2 vWD effeted Dobermans produce a litter of puppies..
this is the Email..I took out the names to protect the breeder and they puppy owner..
My heart is broken. Last night, he began bleeding from his nose profusely. After finally finding a 24 vet, he had lost too much blood, and I was advised to put him to sleep, bc he had ruptured the mucous membranes in his nose and eyes, and was bleeding out, all because of Von Willebrand's disease. I never knew he had it. He bled out so quickly, and his lungs filled with blood. He struggled for every breathe. He was only 7 months old. I hated to see him in so much pain, struggling for each breathe. He stopped breathing twice in the car on the way to the vet. I tried to save him. I couldn't let him suffer anymore. I have lost my best friend. My heart. I am dying inside. How do you go through each day? I can barely breathe, let alone live my life. Sorry to bring up memories, but I am lost and you are the only one I know that would understand the love, and loss:(
this is another long sad story.. Please do not buy from a breeder who does not health test.
This is just one of many stories of why we want people to purchase puppies from GOOD Reputable Breeder, yes it is sad but it is also very true. www.htpuppiescb.com
The Art and Science of Judging
Judging dogs is a combination of art and science, and the really good judges (and breeders) are blessed with and understand the perfect combination of the two.
This illustration diagrams the information you should have about any breed you study. This is the science of learning about correct silhouette, which is created by a sum of correct proportions. Photo from Solving the Mysteries of Breed Type, by Richard G. ("Rick") Beauchamp.
Knowledgeable, competent and honest judges are essential to the showing and breeding of quality purebred dogs. (I know what you’re thinking: "Not more on judging; I can’t take it.” Bear with me, please.) Judges are an integral part of the very foundation of our sport upon which almost everything we do depends; depends, that is, if we are still interested in quality. Show committees need them to construct judging panels that will draw the most entries and hopefully the best dogs to the shows. Exhibitors need them to draw good entries to make up the points in the classes and also in Group and Best in Show points for national ranking.
Some still look to the show ring for evaluation of their breeding stock. But we tend to overlook the most important element in the judging equation: maintaining and/or improving our dogs and the breeds they represent. Excellence in our breeds is more important than show entries, majors or win records, and if we are not pursuing that, then just what are we doing? If we want excellence in our dogs, we need excellence in our judges.
The great Bull Terrier breeder Raymond Oppenheimer cared deeply about his beloved breed and understood this need. He said, "No breed can long continue to progress if it is consistently badly judged, because sooner or later a general air of confusion will grow so that neither the experienced breeder nor the novice knows what to do next. It is therefore of great importance that everybody connected with shows should understand clearly what the term ‘a good judge’ implies so that only men and women who qualify for such a description shall be appointed to officiate on important occasions.”
Why? He goes on to explain, "If the wrong animals are put up consistently, they are liable to be chosen for breeding, which is likely to have a harmful effect on the breed concerned. So it is very important that a high level of judging be maintained, especially at important shows (the breed club and general championship shows), for unless this happens, the general standard of the dogs will almost certainly deteriorate.”
I want to make two points. First, the number of conformation dog shows, all-breed shows particularly, requires a frightening number of judges to fill the panels. Even without knowing that a relatively small percentage of our judges are actually officiating at these shows, we can see that this requirement sets us up for failure almost before we begin. Someone has to judge those shows, and reason tells us that they can’t all be top-flight and can’t all have availed themselves of the essential training and experiences.
Second, I really have no idea how to determine which aspiring judges will rise to the top and be the good ones, the people to whom we look forward to showing our dogs and whom we are eager to put on our all-breed panels. Nevertheless, I’m pretty sure the methods we have been using for the last 20 years have not been all that successful, or else why would we keep changing those methods?
One of the reasons, probably the principal reason, why no satisfactory method of evaluating potential judges exists is the same one that makes educating them so difficult: Judging dogs is a combination of art and science, and the really good judges (and breeders) are blessed with and understand the perfect combination of the two. We seem to believe that we can measure everything and train everyone if we throw enough PowerPoint programs at aspiring judges and test them with SAT-type programs. And isn’t it the artistic part that renders the judges’ decisions subjective rather than strictly objective?
Having "An Eye for a Dog”
Why do we seem to forget that an important element for a great judge is that mysterious element we call "an eye for a dog.” All the great judges had/have it, usually without knowing it because it is so natural to them. Judith Anne Dorothea Blunt-Lytton, the 16th Baroness Wentworth, whom Arabian Horse breeders have always referred to as Lady Wentworth, understood this essential gift. In addition to her Crabbet horses, she was a respected breeder and judge of King Charles Spaniels and wrote a distinguished work on the ancestry of Toy breeds in 1911. She expressed her views on judging dogs in 1950 in the English magazine Country Life: "A good judge must have natural aptitude as well as experience. No amount of training can replace it, and a lot of nonsense is talked about training young judges. Nothing is worse than training in a bad school, and a lot of old judges would have to go to an elementary school themselves before they would be able to teach. Yet the worst judges are often the hottest advocates of Leading the Young Idea, and it becomes a case of the incurably blind leading the short-sighted.”
I can never read that statement without thinking that if a group of people heard her say that today, they would surely ask, in concert, "Why don’t you tell us how you really feel, Lady Wentworth?”
There was an interesting article that appeared in Sports Illustrated before the Westminster show in 1967. The great Percy Roberts, then 77 years old, was the Best in Show judge that year, and his comments on dogs and judging made the importance of that "eye” crystal clear. He was interested in all animals, including cattle and horses, observing them in order to hone his skill at finding quality wherever he could, going to the racetrack, not to gamble but to observe the horses at work. He recalled his Welsh father, a horse dealer, telling him to "never buy a horse that doesn’t impress you when he first comes out of the barn.” He worked as a kennel man for the best breeders, and observed animals of all species and breeds at every opportunity to improve his knowledge of dogs and refine his "eye.” He didn’t do it by looking at photographs and certainly would not by looking at digital images if he were alive today.
There is an entire book dedicated to this subject, An Eye for a Dog, Illustrated Guide to Judging Purebred Dogs, by the late Canadian writer Robert W. Cole. In the conclusion of the book, Mr. Cole writes, "Having an ‘eye for a dog’ combines both science and art. Knowledge of the science of the dog and the ability to develop an appreciation for the art involved are required for the successful judge and exhibitor. On the science side, you must know the purpose a breed serves. This provides the clues as to how the dog should be structured and move. The art involves the ability to recognize beauty, form, symmetry and style ... in other words the dog’s aesthetic appeal. One category complements the other.”
Other livestock judging requires this combination of art and science, even when more scientific qualities are more important, such as milk production, wool quality and the fat/lean balance in beef and other livestock. For example, this from the article "Alpaca Judging: Art or Science?” by Mike Safley: "I have judged 1,000’s of classes over the past 10 years, and I would like to suggest that each decision is not necessarily scientific; there is by necessity a certain art to judging alpacas.”
Tom Horner, the well-known English judge and journalist, is reported to have said that breed standards are like "The Lord’s Prayer.” Even a child can memorize the prayer, but it takes a lifetime to completely understand it. He was another admired judge who clearly understood the art/science balance in judging.
In his Take Them Round, Please: The Art of Judging Dogs, Mr. Horner writes, "Judging is both an art and a science: It is an art because the decisions with which a judge is constantly faced are very often based on considerations of an intangible nature that cannot be recognized intuitively. It is also a science because without a sound knowledge of a dog’s points and anatomy, a judge cannot make a proper assessment of it whether it is standing or in motion.”
In acknowledging the essential gift of talent, he writes, "Knowledge, decisiveness, integrity and the rest of the necessary qualities are useless without one vital possession — ‘an eye for a dog,’ which is the ability that every good judge has to recognize at a glance whether a dog is right or wrong, good, bad or indifferent. A priceless gift, without which no one can make a real success of judging, it is acquired by long and painstaking study of anatomy, breed standards, high-class dogs and poor ones, breed books, photographs and so on, until it becomes an instinctive skill to weigh up the merits of a dog, almost on first sight.”
And once again, who can ever say it better than Raymond Oppenheimer? (And what does it say about the world of dogs or, now that I think about it, me, that most of my references are to English men and women, and deceased English men and women?) In the chapter on judges and judging in McGuffin & Co.: A Bull Terrier History, published in 1964, he describes a good judge. "He must have that flair which recognizes quality, style, symmetry and balance at a glance.” This requirement "is one that can never be learned unless the judge has an artistic sense, and it is the one which will always mark out the first-class judge from the second-class. If a man can see quality, style, symmetry and all-round balance, he has what it takes to make both a great breeder and a great judge.”
Obtaining the Eye
If we can accept the proposition that science and art are both necessary parts of the good judging equation, how do we try to achieve that in our judges, the ones in our future who are just entering the approval process or applying for additional breeds? Most of the people quoted above agreed that these qualities can be attained or, at least, our natural talents can be improved upon. The question is, how? I have a few suggestions.
Does anyone read anymore? There are excellent books in print that would add to everyone’s existing knowledge of dogs, written by people who have talent and experience. In his excellent book, Solving the Mysteries of Breed Type, the author/judge Richard Beauchamp discusses the value of reading expertly written books for both breeders and judges and gives examples of specific ones that he has found valuable in his judging career. Why is reading one of these books not an acceptable component, even a requirement, in the application process? Is having aspiring judges write book reports such a bad idea?
There is nothing to compare with getting your hands on dogs, and on as many dogs as possible. We’re all at dog shows, and it takes very little time and effort to ask an exhibitor outside the ring if we can go over a dog. It may not be a breed we are at that moment interested in judging, but may still enlighten us as to structure or coat texture. And it doesn’t have to be a great dog, or even a good one. How a dog feels under our hands, and learning by experience what that feeling means is enlightening, even as we try not to listen to the owner tell us about the dog’s wins and rankings.
To say that I am not a fan of PowerPoint or slide presentations is a great understatement because both are so often the refuge of the lazy or worse. I am reminded of several breeders I know who will sit in front of their computer or television watching a litter of puppies on video when the very puppies are outside in the yard. Nothing replaces touching and watching the actual dog in living flesh. Otherwise, why don’t we just send photos of our dogs to judges to be evaluated?
Could we require all aspiring judges to write a critique of the dogs judged during the permit phase of the approval process? Writing a critique requires the judge to focus on what he or she saw and forces that judge to prove or disprove his or her actual knowledge of the standard. Of course, writing a critique takes time, and yes, it might slow down the ring a little. But couldn’t we allow fewer dogs to be judged per hour in the pursuit of better judging, better dogs and better breeds? It is a valuable tool for learning as well as evaluating, and I have known some of our best judges to sit ringside and write critiques on the dogs being observed, even dogs they are currently approved to judge, because our best judges always want to know more and to do a better job.
Finally, we need more intelligent conversation about our dogs and our breeds. The talk at club meetings, shows and even specialties is more often than not about a specific dog’s winning record or national ranking, or who has bred to what dog, or what horrible health issues a popular sire is producing. I am always impressed at the high level of discussions ringside and in the dining areas at Scandinavian shows, where there seems to be a more intellectual approach to all aspects of dogs, especially breeding and judging. Is it possible that this approach is at least partially responsible for the consistently high quality of their dogs and, dare I say, their judging?
As a group, we are particularly resistant to change. But if we are truly interested in better judging, in the product and not the process, there are many options we could consider. May I suggest that the proposed AKC Canine College, which would provide online educational opportunities, might be an acceptable method to train some architects or some engineers, but not those seeking the art in judging dogs?
All judges are not created equal and do not approach judging with the same talents, with that natural understanding of balance and beauty, that "eye for a dog.” And, in the end, we are all going to have to be satisfied with a wide range of expertise in our judges. But can’t we do a better job in finding those especially talented ones and give them every assistance possible to advance? I know we can be more creative in helping to develop that essential "eye” in all aspiring judges who are willing to put in the time and effort to that end.
From the May 2014 issue of Dogs in Review magazine. Subscribeto receive 12 months of Dogs in Reviewmagazine, or call 1-888-738-2665 to purchase a single copy.