The world’s most complex and comprehensive genetic test for dogs, MyDogDNA, has been available to all dog owners for about a year. During this time, Lagottos have been tested to the extent that it is possible to get an overview of the genetic variation in the breed. The Lagotto enthusiasts have also gratifyingly adopted the MyDogDNA Breeder –tool that is based on the test results in the MyDogDNA database in order to treasure the breed’s genetic diversity. At the same time, MyDogDNA has also revealed the occurrence of a breed hereditary genetic defect that may predispose to formation of urine stones. An overview of the Lagotto Romagnolo breed MyDogDNA results provides a good example of how genetic information can simultaneously help maintain health-enhancing genetic diversity, and control individual hereditary diseases.
Overview of genetic diversity in Lagotto Romagnolo
The width of the gene pool of the Lagotto Romagnolo breed is evaluated, for example, in the breed clubs’ breeding strategy program documentation. Comprehensive statistical pedigree databases provide good opportunities to have a look, e.g., at the average COI and the effective population size, as well as to estimate the potential overuse of certain individuals for breeding. As additional support for this information, MyDogDNA offers yet another approach to evaluate the size of the gene pool and the level of inbreeding, i.e. a molecular genetic assessment of genetic diversity within the breed. This approach is based on measurement of the level of heterozygosity, that is, the proportion of evaluated genomic sites in which the dog has inherited a different gene form from its dam and sire.
Figure 1 illustrates the level of heterozygosity in the Lagotto Romagnolo breed. The figure gives up-to-date information on the situation, which is currently based on a sample of more than 300 dogs. The median diversity for the breed is 29.6 % (distribution 17.9 % - 34.1 %), while the median for all dogs is 28.8 % (15.3 % - 40.1 %). Significant geographical differences in the heterozygosity level were not observed (table 1), but with the exception of Finland, the sample size is not yet large enough to conclusively review this. A future goal for the breed could be to increase the number of tested dogs of other origin through co-operation projects and networks. The diversity level of the Lagotto breed is compared to other selected breeds in table 2.
Based on the current sample, the Lagotto Romagnolo seems somewhat more diverse than MyDogDNA analyzed breeds on average. A breed’s basal level of genetic diversity can be understood not only by examining the current breeding practices but also by knowing the breed’s history (e.g., number of and variation present in founder dogs, any encountered genetic bottlenecks such as the World Wars). In lagottos, quite a lot of variation in diversity levels seems to occur between individuals. The breeding committee of the breed club may want to evaluate the kinship or background of the dogs at the extremes of the distribution in order to understand the observed variation. It is worth keeping in mind that a healthy and good-natured dog that has a low level of diversity is no worse as an individual than others – genetically it can even be a very good partner for other dogs that do not carry similar gene forms. In the long run, it is worth paying attention to sustainable breeding practices in order to maintain any breed’s overall well-being. In its simplicity, this refers to breeding practices that aim to minimize the loss of gene forms and narrowing the breed’s gene pool as well as to increase the genetic diversity. The Finnish breed club breeding strategy guideline documentation for the Lagotto sets up restrictions related to mating close relatives as well as to the recommended amount of offspring of an individual. In the documentation, the stud book is noted to still be open, which in turn allows introducing new gene forms into the breed. Keeping both breeding stock and gene pools as wide as possible is indeed particularly important for the Lagotto breed that has climbed quite quickly from a limited number of founding dogs to become one of the 100 most popular breeds ( in Finland). Bringing “new blood” into the population of a specific country with imported dogs is particularly important to make such rapid growth sustainable.. In addition, Lagotto enthusiasts have gratifyingly adopted the MyDogDNA Breeder –tool, included as a part of the MyDogDNA service, that helps identify genetically optimal mating pairs (i.e. mating pairs that help increase genetic diversity in the offspring).
Figure 1. Diversity distribution in the Lagotto Romagnolo breed. The blue curve reflects the genetic diversity distribution of the Lagotto Romagnolo breed (N = 307). The peak of the curve indicates the most common diversity levels in the breed. The median is marked on the graph with a dot. For comparison, the orange curve illustrates the current distribution for all dogs in the MyDogDNA database. For further reference, the curve of other breeds in the same FCI subgroup is shown (water dogs, green curve).
Table 1. Geographical distribution of heterozygosity level (% heterozygous genetic markers of the total evaluated markers).
Table 2. Average level of genetic diversity in selected breeds.
Geographical differences within the breed
Figure 2 shows how similar or different the tested Lagottos are. The Finnish breed club has stated in its breeding strategy documentation that one of the possible breed problems is that even on a global level, all Lagottos are more or less derived from the same original lineages. This is one plausible explanation for why different Lagotto populations are not clearly distinguishable in the figure, though certain sub-groups, such as the Australian dogs, do stand out as a clear subpopulation. The most important conclusion that can be made from the figure is the fact that imported dogs can not automatically be assumed to bring a large number of completely new gene forms e.g. into the Finnish population. The aforementioned MyDogDNA Breeder tool creates virtual matings through which it is possible to get an idea of how much “new blood” an imported dog actually brings into the population, or evaluate if it is, in fact, genetically similar to the existing dogs. Modern genetic information can thus be used as a tool in practical breeding - as one selection criterion among others (such as character and structure).
Figure 2. Genetic differences in the Lagotto Romagnolo breed. Each dot on the graph reflects an individual dog. In the figure, dogs that are close to each other are genetically similar while dogs with distance are more different.
Hyperuricosuria occurs also in the Lagotto Romagnolo breed – should the genetic defect be accounted for in breeding?
As part of the MyDogDNA analysis each dog is tested for approximately 100 genetic defects that cause known inherited disorders (http://mydogdna.com/sites/default/files/files/mydogdna_tested_disorders_and_traits_2014.pdf). Of the examined genetic defects only juvenile epilepsy had previously been found in the Lagotto Romagnolo breed. According to the MyDogDNA database, 30.4 % of the tested Lagottos carry the mutation for juvenile epilepsy.
MyDogDNA’s approach to screen comprehensively for genetic mutations has proven to be successful. We have made many new discoveries, i.e. found mutations for the first time in breeds in which they have not previously been known to be present. What is essential for the Lagotto breed, is our new observation that about 9 % of the dogs within this breed carry the genetic defect that causes hereditary hyperuricosuria (HUU). HUU is a potentially painful urinary tract and kidney disorder in which excess urine acid accumulates in urine. This leads to formation of uric acid crystals in the urinary tract, which may manifest as frequent urination, difficulties in urinating, blood in the urine or urinary tract infections. General symptoms include weakness, fatigue, loss of appetite, or vomiting. HUU is inherited in an autosomal recessive manner, i.e., according to current knowledge, the dog needs to inherit the mutation from both parents in order the disease to manifest. Carriers don’t have any symptoms.
After a new finding, we always strive to ensure with further examinations that the effect of the mutation manifests also in the new breed. The HUU findings are currently subject of research, which seeks to clarify the effect of the genetic defect for the Lagotto breed. However, it should be noted that the HUU mutation has previously been found in about 15 different breeds. For this reason, many laboratories are automatically offering the HUU genetic test for all breeds, even though there are no scientific publications that confirm its impact or prevalence in all breeds. By examining the Lagottos, we are aiming to confirm the finding by following an appropriate and precise scientific process. However, most likely it is wise to avoid mating two Lagotto HUU carriers. Carriers should by no means be excluded from breeding, but it would be good to choose a partner that has been tested clear for the same mutation.
Towards healthy and active dogs in the future, with the support of genetic information
The importance of genetic diversity has been recognized for a long time, but only now, modern genetic technology is available for all as a breeding tool. Narrowing of the gene pool is a long term threat to the breed; on the other hand, the immediate life and health of an individual dog may decisively depend on a single mutation causing genetic disorder. For this reason, we believe that combined technology simultaneously exploring level of diversity and individual mutations is the most appropriate tool for canine DNA diagnostics. At the same time, information about other hereditary characteristics, such as coat color or coat type can be collected.
In dog breeding, there is no reason to be afraid of the information gained by genetic testing. For many breeds, genetic tests are a routine part of breeding selections. Modern genetic tests are easy to order and use as a supporting tool for breeding, along with other criteria important to the breeder. The comprehensive MyDogDNA testing concept includes also a unique DNA profile for each dog that can be used e.g. for parentage confirmation. Another huge advantage that panel testing enables is a low price compared to performing each test individually.