When in recent years it was possible to reliably determine a dog’s hearing using apparatus (BAER test) and identify not only bilateral, but also unilateral deafness, it turned out that among Dalmatians the highest percentage of deafness from all dog breeds. This fact suggests that in breeding a certain factor is acting that increases the percentage of deaf individuals.
It is believed that Dalmatians suffer from a congenital, hereditary, neuromuscular form of deafness. Microscopic studies have shown that in the first weeks of a puppy's life, the vessels of the cochlea of the inner ear atrophy, followed by further deterioration of the components of the inner ear and nerve degeneration.
At the same time, the inheritance path cannot be established. This is clearly not a dominant, but not an autosomal recessive type of inheritance, since there are cases of birth of normally hearing puppies from two deaf parents. Sex dependence also could not be established. But it is reliably known that among Dalmatians with a congenital spot there are practically no deaf dogs.
Since the dependence of deafness on white color is known, you can try to consider the mechanism of color formation of Dalmatian and other breeds related or similar in color, compare the distinguishing moments and principles of selection and, thus, try to find factors that increase the likelihood of deafness in Dalmatians.
It is known that the initial ("wild") is solid color, and depigmentation appeared during domestication and is due to a gene that inhibits (suppresses) the formation of pigment cells.
The pigmentation process is ordered in time (Ilyin, Robinson). The first pigment spots appear on the head of the embryo, then spread along the spine. These are the so-called "centers of sustainable pigmentation." Also known are the "points of initial depigmentation" (Ilyin), which are the points of completion of pigmentation. Therefore, it can be assumed that the color of the white-spotted dog is determined by the time the pigment inhibitor gene takes effect, which, therefore, refers to quantitative polygenes.
In favor of quantitative conditionality of the color speaks and splitting the intensity of color in the offspring. The vector of natural selection is directed towards the solid ("wild") color, the vector of artificial selection is in favor of lighter individuals.
Since pigmentation in most breeds has always been completed by the time of birth, the pigment inhibitor gene also acts only in the prenatal period. Dalmatians and English setters are distinguished from other breeds (English and French bulldogs, greyhounds, bull terriers, etc.) only by the ability to postnatal pigment formation (T gene), which only masks their true degree of depigmentation.
By the way, thanks to this, on the example of the Dalmatian, you can clearly observe the staining process, which in other dogs occurs before birth. The pigment appears at the beginning in the form of points on the skin, which concentrically expand, merge with neighboring points, etc. The hairs are colored later, from the root to the end, and from the center to the periphery of the spot. That is, the coat dyes in the same sequence as the skin, only with a slight delay in time (it is known that by 33 days everything is apparently formed in the dog's embryo, but there is no wool yet).
Imagine the staining process in the diagram:
C) the depigmentation process (as the accumulation of polygenes, the inhibitor gene comes into effect earlier and earlier, until the pigment completely disappears on the skin).
/ 1-2 / - the period of formation of primary pigmentation centers.
Since the process of pigmentation is determined in time, like the entire process of embryogenesis, certain stages of color formation should correspond to certain stages of embryo formation.
Pigment cells are formed in the ganglion plate (nerve crest), which also gives derivatives such as nerve cells of the spinal cord and sympathetic nerve nodes, adrenal medulla cells, cartilage and bone cells, epidermal cells of the skin and hair, as well as cells of the inner ear (cochlea) .
It is possible that a factor inhibiting the formation of nerve cells also has an inhibitory effect on other components of the ganglion plate at the stage of dependent differentiation (the stage of greatest interdependence.
In particular, American medicine considers human pigmentation disorders (including hypomelanism) as a pathology. The treating doctors are urged to see in such violations not only a cosmetic defect, but also to seek violations in the work of other organs originating from the ganglion plate of the embryo. A person also has a number of syndromes combining pigmentation defects with hearing, vision, etc., in particular Vandenburg syndrome: deafness + extensive white spots on the skin.
Since the topography of organs in the embryo is hardly consistent with the topography of certain genes, that is, it is unlikely that the genes of organs developing from the ganglion plate are closely adjacent to the same chromosome (especially since the number of chromosomes in a person and a dog is different), and the structure of all these organs is determined polygenically, then most likely we are not talking about linked inheritance.
It is more likely to suggest a violation of embryonic development under the influence of some biochemical factors that disrupt the synthesis of melanin. Since the genetic conditionality of the color in dogs (in this case, hypomelanism) is not in doubt, the root cause of the remaining disorders should be sought in it. That is, it can be assumed that deafness in Dalmatians and other white dogs is not of an independent hereditary nature (there is no "deafness gene").
It can also be assumed that primary centers of pigmentation are markers of the completion of the discrepancy between pigment cells and the primordia of other organs, and the transition to the stage of independent differentiation.
These pigmentation centers are therefore “stable” because completely white dogs do not appear or do not survive outside the artificial selection factor. The boundary of natural selection passes on our scheme to the right of point "2". From this point of view, the fact can be explained that among the white greyhounds and bulldogs there are many deaf people (“almost all” - Ilyin), and among white bull terriers not only deafness was noticed, but also a general weakened constitution and low vitality (Ilyin). Actually, the selection for a pure white color was only for the bull terriers, but since the working requirements prevailed over the decorative ones, the dogs with a spot on their heads were not rejected, and the percentage of pure white bull terriers was not so high. Similarly, in all other breeds, including the English setters: the vast majority of dogs have spots on their heads.
Let us designate the place of the Dalmatians among white-spotted dogs in the following diagram:
1 - white dogs (leucists, albinoids)
2 - partially formed centers of stable pigmentation (one black ear, monocle)
3 - fully formed centers of sustainable pigmentation (typical color of spaniels, gundogs, hounds, St. Bernards and other breeds)
Most white-spotted breeds are located on the diagram to the right of point "3" (including outbred dogs).
On the segment "2-3" - part of the bulldogs, greyhounds, English setters and bull terriers. The latter can be pure white (to the left of the "2" point), but the% of such dogs in the breed is lower due to the fact that bull terriers and setters with an inborn spot are not rejected. And only in Dalmatians the tribal core is kept exclusively in the “1-2” segment.
The current Dalmatian population consists of 90% albinoids, about 10% are Dalmatians with a congenital spot (but they are unconditionally derived from breeding). The "left" part of the population, which is not part of the breeding group, consists of the least pigmented dogs (too few spots, incomplete eye contouring, unpainted nose, blue eyes).
It is interesting to note that as a result of selection, we often see Dalmatians, bull terriers, English setters with only one colored ear. Therefore, we can assume that the formation of these two symmetric centers of pigmentation does not coincide in time. It can be assumed that the course of formation of paired hearing organs does not coincide in time. One way or another, testing revealed about 5% of deaf Dalmatians in both ears and from 20% (in England) to 30% (in the USA) of deaf in one ear.
It seems that the presence of white spotting, blue-eyedness and deafness can be combined into one syndrome with an irregular frequency of manifestation and severity, which is explained by the fact that only color is genetically determined in this syndrome, and the remaining pathologies are a consequence of a violation of melanin synthesis at the very early stages of embryonic development . For this reason (again, without strict determinism), a higher percentage of pathology should be expected with an earlier violation of melanin synthesis and a decrease in the percentage of pathologies in more pigmented dogs. Moreover, the formation of the initial centers of pigmentation on the head (a symmetrical mask) can be considered the boundary of safe depigmentation.
If deafness in Dalmatians is really caused not by special genes, but by the side effect of depigmentation, this probably also explains the irregularity of the appearance of side effects, which can be single, multiple and appear in different combinations. In some dogs this may be deafness, in others weakened cardiac activity, etc. The weakened constitution, if any, is also not systemic in nature: for example, a thinner skeleton, less durable ligaments can be combined with a voluminous chest, a massive head and etc.
It can also be assumed that the most direct method of influencing the dynamics of the percentage of deafness in a breed will be selection by color intensity, rather than culling one-sided-deaf Dalmatians while striving for a lighter color.
In almost all old realistic images, we see Dalmatians with a darker color than modern dogs, with black (at least marble) ears, often with a double-sided mask.
The first Dalmatian standards were adopted in the 19th century. They outlined the direction for improving the color: the priority was given to dogs whose spots do not merge, including on the ears, the congenital spot was declared a disqualifying sign. And although genetics did not yet exist, the connection between white color and deafness was already known then. But the spotted Dalmatian was not perceived as a white dog - and so on!
Moreover, at that time the breed turned out to be “unemployed” and its phenomenal physical data (strength, endurance, speed, requiring not only a strong musculoskeletal system, but also a healthy respiratory and cardiovascular system) were not claimed. The breed moved into the category of ornamental, and selection by working qualities ceased (at exhibitions, the color was estimated at 30 points out of 100, and limbs at 15 points!). Further advances in veterinary medicine and vaccination have minimized natural selection factors.
Currently, a new stage begins in the selection of Dalmatians. Thanks to the BAER test, it became possible to identify unilaterally deaf dogs that will undoubtedly be removed from the breeding (in the diagram, this is the left, lighter part of the population). The breed will be influenced by two oppositely directed selection factors, which in itself will narrow the genetic base. But since we not only exclude dogs with a congenital spot and darker from breeding, but also shift the breed towards albinism, the culling process becomes endless, which leads to genocide of the breed (up to 20% reject by color + 30% by deafness) . About selection by anatomy and character, especially in small populations, it is not necessary to speak at all.
There is another aspect of this problem. Not only is the most healthy part of the population still being destroyed, now a huge number of beautiful and practically hearing, but one-sided deaf dogs will be deduced from official breeding. That is, a parallel population will arise, where uncontrolled breeding "in itself" will inevitably begin, which, with real physical weakness of this part of the breed, will quickly lead to degradation and compromise of the entire breed in the eyes of the overwhelming majority of the uninitiated.
In the official population, while not understanding the true root cause of the problem, in the midst of a search for the mythical “deafness gene”, many worthy producers can be compromised and removed from breeding.
About selection methods
If deafness and, possibly, other problems are the result of selection by color, then the Dalmatian breed can be attributed to breeds of "risky selection" (if we call it selection in the direction opposite to the direction of natural selection), which requires appropriate, more careful selection methods.
It is important to realize that aesthetic requirements at a certain stage conflict with the working criteria and even begin to threaten the physical health of the dog. In this connection, it is necessary to solve, first of all, fundamental questions: whether the unique physical abilities and good health will be preserved in the breed - and then it would be more expedient to retreat to an older type of color, darker in general, often with an inborn spot. Or the breed finally goes into the category of purely decorative ones and selection will continue along the line of color improvement, and then inevitably it will be necessary to lower the bar of physical requirements, including by ear.
In any case, it is hardly possible to work with strict methods in the “risk zone”: on the one hand, by selection by color, produce physical imperfections, and then unconditionally reject dogs obtained as a result of such targeted breeding.
The most appropriate solution seems to be a compromise. Intensively colored Dalmatians with marbled ears (and this is the majority of the standard population) still demonstrate high working qualities and good health. It would only be necessary to shift some emphasis in the standard: give preference not to spotty, but to marble ears, to be more loyal to merging spots (since individual spots are more characteristic of puppies that are least pigmented at birth).
Perhaps it is not necessary to exclude deaf dogs from one-sided breeding if they have an outstanding exterior, but select more intensely colored partners for them, perhaps from among the dogs with a congenital spot that are also outstanding on the exterior. Since if it is confirmed that deafness is caused not by a single gene, but by a quantitative color factor, the breed is unlikely to be clogged with a “recessive deafness gene”.
If we take into account that in our country at present the use of the BAER test is not very realistic because of its significant high cost and the vast territory of our country, the possibility of regulating the percentage of deafness through color is of particular importance to us.
Prepared based on the materials of the Dalmatian World Yearbook.
BAER test (hearing test) in a Dalmatian puppy without a relaxant in the symphony of Stars kennel. (December 2019).
The Dalmatian is an immediately recognizable dog breed because of their distinctive spotted coats and outgoing personalities! Indisputably attractive thanks to both their cheerful nature and attractive appearance, the Dalmatian is a popular choice of purebred dogs for many people, and one that is completely at home among families with children. They are generally considered a hardy, healthy breed that often lives up to a relatively old age and is not susceptible to a particularly wide range of genetic and inherited health problems. However, the Dalmatian has a genetic predisposition to deafness and other hearing impairments, and many dogs of the breed will be affected to some extent by hearing problems.
Read on to learn more about the Dalmatians and deafness, as well as the role played by the genetics of the Dalmatian coat.
Dalmatian health and life expectancy
Dalmatians have an average life expectancy of 11-13 years, although it is often good for Dalmatians to live in their late teens. Dalmatians have increased risk factors for a number of health conditions that are considered breed-specific and herediatary, including:
- Urinary stones
- Hip Dysplasia
However, a condition commonly associated with the Dalmatians, and one that is more common than any other problem, is deafness.
Dalmatian coat and color
While everyone is familiar with the spotted appearance of the Dalmatian coat, Dalmatian females are actually born pure white and are just starting to grow their spots in about three weeks.
Most spots will be present by the time the puppies are four weeks old, although these dogs will continue to develop spots much more slowly throughout their lives. Dalmatians can usually be seen with black spots or yellow spots on a white coating, although other rarer color variations, such as blue, tiger, orange and lemon, can also be seen. Spots or spots of spots cover the entire body and are usually denser around the ears and head.
Dalmatian has a short, thin layer that is stiff and sinewy and relatively easy to care for. Dalmatians will shed hair all year round, although their skin is not particularly oily, and they are usually considered one of the less smelly dog breeds!
Dalmatian deafness and hearing problems
Dalmatian has a pronounced genetic predisposition to deafness, about 30% of the dogs of the breed to some extent suffer from deafness or hearing loss.
Deafness is often associated with coat color, and it is now known that genes that provide piebald (spotted on white) or an albino coat can also cause deafness due to the lack of mature melanocytes (melanin producing cells) inside the inner ear. This problem may affect both one ear and both ears, and will not necessarily be present on all dogs with paybald or albino.
Blue eyes in Dalmatians are also associated with an increased likelihood of deafness, and in Dalmatians, who have blue eyes rather than brown, are exponentially more likely to be deaf, although it is not yet known why this is so. While the blue eyes of Dalmatians will not always be deaf, the blue eyes of a dog are considered by many authorities of the breed to be guilty, and breeding of blue-eyed dogs is sometimes discouraged.
It was found that Dalmatians, whose coats are more spotted than spotty, for example, when the spots are so close to each other that they form large spots of a darker pigment, the frequency of deafness is much lower. While breeding for a coated coat rather than a spotty coat can ultimately help reduce the incidence of deafness throughout the breed as a whole, this is currently not recommended. The standard model for Dalmatian breed hair consists of spots, not spots, traits that breeders and breed authorities seek to preserve.
Deafness in both ears of a Dalmatian is known as bilateral deafness, while deafness in one ear is called unilateral. The ability to hear effectively with both ears is known as two-way listening, and only Dalmatians who have bilateral rumors should be used for breeding. Many Dalmatian breeders will test for puppies that they produce prior to sale to test the auditory ability of the dog in question.
While deaf or partially deaf Dalmatians should not be used for breeding (as they are exponentially more prone to producing deaf puppies), there is no reason why deaf Dalmatians or any other deaf dogs will not make large pets.
Many deaf and hard of hearing dogs lead a full, happy life and can be trained, cared for and kept safe by a bona fide owner. Training and living with a deaf dog needs to be approached quite differently than training an auditory dog, but there are many alternatives to get your dog's attention than the usual vocal teams that most of us use.
For more information about training and managing a deaf dog, check out our previous articles on training a deaf dog and living with a deaf dog.
Dalmatian spots color
Dalmatian spots are not always black. Dogs with brown spots are less common, because the recessive gene is responsible for the brown color. Only dogs with a white-black and white-brown color are allowed to exhibit. However, sometimes representatives of a breed of a different color are born, for example, lemon, gray (blue) color and even tiger color.
Color brown stains can range from light brown to rich chocolate. Sometimes dark brown spots can be mistaken for black ones, but upon close examination, it is easy to notice the difference, especially when you consider that the pigmentation of the nose and eye rims in white-brown Dalmatians is always liver-colored.
Behind blue (gray) color in the coat color corresponds to the recessive gene. Such puppies are born from parents, one of which was white-black and the other white-brown, or from white-brown parents who are carriers of the recessive gene responsible for the blue color. Such puppies are rarely born.
Animals with lemon (peach) color appear due to a gene that forbids black and brown to appear. Pigmentation of the nose is usually black or brown. When buying a puppy of brown color, the color of the spots of a light brown shade should be carefully evaluated, because unscrupulous breeders can give puppies with a non-standard color as purebred.
Tricolor dogs are rare. The color is characterized by the presence of black or brown spots with a tan in those places that are characteristic of the Doberman breed (legs, chest). The tricolor dog is a carrier of the tricolor gene. It is possible to notice the manifestation of tri-color only at an older age. At the time of the sale of the puppy (1.5-2 months), tricolor is not always manifested. The third color is always red, so do not confuse it with lightening spots on the head of individuals with a brown color.
Brindle color is rare. The spots are dark striped, for example, red-brown or red-black. Such animals cannot participate in exhibitions and breeding.
The color is transmitted from parents, so when breeding dogs it is important to consider the size and number of spots in the bitch and dog. So, for example, if one of the parents has large or too many merged ones, then a puppy with the same peculiarity is more likely to appear. But even from ideal parents in color, a puppy with small or large spots inherited from grandparents can be born.
Congenital spots in Dalmatians
Pedigree marriage is considered to be puppies with dark spots at birth. Usually they are larger than normal, their forms are diverse. They can be present on any part of the body, but most often they are located on the head, ears, paws, stomach, tail. One or several puppies with this defect may be born in the litter. Such dogs become companions; an exhibition career does not shine for them. Offspring from parents with congenital spots are not recorded.
It is easy to distinguish the type of spots in an adult. Sometimes merged spots are taken for congenital large, and vice versa. But on the merged, there are always several white hairs, and the congenital one is perfect in color (completely black or brown). In addition, the edges merged are uneven, while the congenital ones have very smooth borders.
There is such a concept of “frost” when the spots on the Dalmatian overlap with separate white hairs. This concept is incorrectly applied to puppies, because their color is still being formed, and naturally the tips of white hairs will overlap spots, the size and shape of which are distinguishable.
It is a completely different matter when a gray dog appears on the spots of a mature dog. Here, due to age, changes in color occur. In older individuals, gray hair appears most often on the muzzle and ears.
If “frost” is really present in puppies, then with age it will not disappear. “Hoarfrost” is either there or it is not.