HEREDITY
IN THE DOG

[ABSTRACT.]  JUST as some outstanding advances in other scientific fields— advances of very great value to humanity—have been made with the help of dogs, so their use in certain fields of genetic research seems to offer the most practical means of attacking some very important but difficult problems, notably those connected with the inheritance of psychological characteristics. Because they show so wide a range of intelligence, aptitudes, and temperament, and can be handled easily dogs appear to be better adapted to studies of this kind, especially with our present limited methods of measurement, than any other animal. Aside from the possibility of improving one of our most useful animals through such studies, there is the still more significant possibility of adding materially to knowledge of mammalian genetics, especially the inheritance of psychological traits—a field in which relatively little progress has been made.

NO OTHER animal serves so many widely different purposes or has been so plastic in man’s hands as the dog. Those characteristics by which dogs differ most from other domestic animals and which make them especially useful to man are largely of a psychological nature such as intelligence and willingness to cooperate. This can be especially appreciated by one who has watched a trained sheep dog working a quarter or half mile away from his master, yet obeying every signal that his master gives.

Partly because of their original inheritance and adaptability and partly because of the great variability that has resulted from centuries of selection, dogs today serve man as hunters, retrievers, guards, companions, aides in war, herders of livestock, police aides, guides, draft animals, entertainers in sports and shows, subjects in medical and scientific investigations, scavengers, fur bearers, and in case of necessity as food. Many of these uses can be subdivided and doubtless others might be given.

The range in size is so great that some animals in the largest breeds weigh 100 times as much as other normal individuals of the smallest breeds. An Irish Wolfhound standing on his hind legs can often look over the head of a tall man, while some full-grown Chihuahuas may stand comfortably on one’s outstretched palm. Not only in size but in form, physique, temperament, aptitude, and intelligence there is great variation. Long, short, wide, narrow, tall, squat, slender, chunky, graceful, awkward, excitable, placid, robust, delicate, intelligent, stupid, friendly, savage, affectionate, self-contained, dignified, ridiculous, ugly, and beautiful are terms that might be aptly applied to different breeds and individuals. Figure 1 illustrates some of the wide variations in type.

Figure 1.—Variation in body form, type of coat, and color patterns as shown by some popular breeds of dogs in the United States. A, Pointer; B, German Shepherd; C, Toy Poodle; D, Bulldog; E, Dachshund; F, Pekingese; G, Cocker Spaniel; H, Chow; I, Scottish Terrier; J, Fox Terrier; K, Greyhound; L, St. Bernard. (C, D, and L by courtesy of G. Howard Watt, Inc.)

In many of the breeds there is a so-called “standard” size, but there also may be a small or “toy" size, and sometimes a giant size. There are varieties with smooth, wire-haired, curly, long, stand-off, or corded coats.¹  Some breed standards permit all colors, others certain variations in color, and others only a single color or color pattern. Later in this article the causes for much of this variation will be discussed.

It is certain that doglike animals existed on the earth thousands of years ago. The origin of the dog (Canis familiaris), however, is not known. There is considerable speculation as to whether dogs originated from such present-day wild species as wolves, jackals, and dingoes, with which they will interbreed (fig. 2), or from other forms now extinct.

Figure 2.—Hybrid from a German Shepherd dog and a female wolf. (Photograph by courtesy of John Gans and Fachschaft für Deutsche Schäferhunde after von Stephanitz (54).)

Quite probably they trace to more than one of these sources. It has often been supposed that the fox, which has many doglike characteristics, was one of the ancestors of the dog. However, few, if any, authentic cases of successful crosses between these two species are known,² although numerous unsuccessful attempts to cross them have been reported. Accordingly, it appears improbable that the fox has played a very large part in the ancestry of our present dogs.

Students of the antiquity of the dog, Studer (57, 58),³ Breuil (7), Elliot (15), Osborn (46), Allen (2), von Stephanitz (54), and Clark (10) are agreed that dogs were domesticated before any of the other animals’ but how long ago they do not know.  In Europe bones of dogs have been found associated with the remains of men who invaded Europe at the close of the Paleolithic or Old Stone Age, and at the beginning of the Neolithic or New Stone Age. Since earlier remains of dogs have not been found in Europe, apparently they were brought to that continent by the pre-Neolithic peoples and were probably already partially domesticated, serving possibly as scavengers and guards and for food. This makes it seem probable that the dog was first domesticated in Asia at an even earlier date. Somewhat more recent evidence of domestication has been left us in the form of crude pictures carved by prehistoric man (fig. 3) showing dogs used in the chase (8, 35).

Figure 3.—Prehistoric rock tracing representing reindeer, a horse in a boat, men, and dogs. Cut in the quartz at Massleberg, Skee Parish, Bohuslin. Height, 5 feet; width 1214 feet. (Courtesy of Cassell & Co., London, after Leighton (35).)

DOGS AS FARM ANIMALS

Dogs have held an important place in agriculture and rural life for centuries. Probably they have been most important to the American farmer in guarding property, herding livestock, contributing to the sport and the larder of the master when he goes hunting, helping exterminate vermin, and as companions and pets. While it is impossible to estimate the value of these services, one can hardly imagine a cheaper or more efficient guard service for the farm than that furnished by a good watchdog, and if the same animal serves in other ways, as it often does, one can be sure that its value considerably exceeds the cost of keeping it. The value of dogs as companions, especially where people lead rather isolated lives, as they sometimes do in certain agricultural districts, is often underestimated. And what other animal gives the growing boy, either on the farm or in the city—or the growing girl, for that matter—as good an opportunity to learn self-control and consideration through the care and control of his pet?

According to an old saying, there is no good flock without a good shepherd and no good shepherd without a good dog. There are without doubt some exceptions to this, but there is no doubt that a trained herding dog is a great help and under some conditions indispensable in handling livestock. Many farmers enjoy hunting so that good hunting dogs are found on many farms. If one were to estimate the percentage of the 6,812,350 farms ⁴ in the United States that have at least one dog from the sample of which he has personal knowledge, it would certainly be very high.

ALTHOUGH dogs have been domesticated for many centuries and have been successfully molded into many forms adapted to man’s uses by the processes of heredity and selection, most of the breeds we know today have originated in comparatively recent time, and up to within a few years ago there had been very little, if any, breeding work with dogs that could be considered of a ‘scientific nature.

However, there is a considerable store of scientific information concerning various aspects of the dog. Anatomists, physiologists, and psychologists have found the dog an excellent subject, especially in connection with medical research, for studying mammalian characteristics. In fact the diet, physiology, and temperament of dogs make them indispensable for certain types of experiment. Some of the outstanding advances in physiology, psychology, and medicine have been made with the help of dogs, as for example the work on conditioned reflexes by Pavlov (48) and much of the fundamental information on artificial respiration, and the control of diabetes and pernicious anemia (9).

In addition to the gain for humanity that has resulted from these experiments, dogs have been used, of course, in the study of their own disorders. The control of hookworm following the work of Hall (19) and of distemper resulting from the investigations of Dunkin and Laidlaw (13, 14, 30, 31, 32, 33), who were provided with funds by the Field Distemper Council in Great Britain, has been made possible by the use of a relatively small number of dogs in the laboratory.

Although the results obtained in some of these researches indicate that the dog would serve as an excellent subject in the study of certain aspects of mammalian genetics, few systematic attempts have been made to obtain information on inheritance in this animal. However, many reports dealing with various aspects of the genetics of the dog have been published. The characters reported in these papers will be considered in this article in the following order: (1) Cytological (concerned with the chromosomes in the cell), (2) psychological, (3) morphological (concerned with form and structure), and (4) color.

Investigators are in disagreement as to the number of chromosomes in the dog. Thus Malone (40) has reported the number in the body cells as being 21 and 22 in the male and female, respectively ; Minouchi, according to Oguma and Kakino (44), has reported 78 chromosomes in the body cells of both the male and the female; Painter (47) has reported the number to be about 50, probably 52; while other investigators have found intermediate numbers (29).

In the study of mental characters psychologists have been able to measure various abilities of dogs such as the speed with which they form conditioned reflexes or immediate reactions to a given situation constantly repeated; their powers of discrimination with regard to visual objects and sounds of different kinds; their ability to make delayed responses to stimuli; and their ability to solve problems such as the opening of a box to get food or finding their way out of a maze or labyrinth. Since most such measurements are difficult to make accurately and require considerable time and expense, practically no information exists on the variation in these abilities among dogs of the various breeds and strains or on the mode of their inheritance.

Some information has been collected regarding the inheritance of certain aptitudes in dogs, as is shown in the appendix. For example, both Marchlewski (41) and Whitney (64) have reported that the aptitude for hunting with the head carried high appears to be dominant to the aptitude for hunting with the head carried low when certain strains or breeds of dogs are crossed. Although the list given seems impressive, it presents information on relatively few of the great variety of aptitudes possessed by dogs and most of the conclusions are based on a few observations only and have not been completely confirmed.

One of the best studies of temperament in dogs and the practical application of genetic principles to breeding dogs with superior abilities is that of Humphrey and his associates in producing and training dogs for leading the blind, and for police and army service, at Fortunate Fields, Switzerland (reported by Humphrey and Warner (22)). The tests used were largely subjective judgments by the trainers and while it was apparently impossible for them to determine the exact mode of inheritance of most of the characters, they were able by assuming that certain of these characters were largely controlled by a few major genes to make marked progress in producing superior animals.

In addition to mental traits, such body characters of the dog as conformation, functioning of internal organs, fertility, and resistance to disease play an important part in his usefulness. The body characteristics that have been studied genetically are listed in the appendix. Of particular interest in this connection is the work being carried on in this country by Stockard (55) and his associates at the Cornell University Medical College on the genetics of modified endocrine secretion and of associated form patterns—such as head shape—among dog breeds. (See the reported findings of Stockard and Vicari in the appendix.)

Although the color of the animal is a body character, it is so easily differentiated from other characters that it seems best to consider it separately. The third part of the list (p. 1337) gives the color characters in dogs for which information concerning the mode of inheritance has been reported.

On the whole, where more than one investigator has reported on the inheritance of a color factor, the results have been similar or the differences can be reasonably well accounted for. There appear to be marked similarities between color inheritance in dogs and that in rodents and in other carnivora (18), which makes some of the conclusions appear reasonable even where the evidence from dogs themselves is rather scant. No cases of proved linkage have been reported.  There is, however, fairly good evidence that there are a number of allelomorphic (alternative) series of genes that affect color in the dog.  These have been summarized briefly in table 2 in accordance with what seems to be the best evidence available. Some genes, exhibit multiple effects, such as those caused by the gene for dominant irregular spotting, which in addition to affecting the coat color produces defective sight and hearing, frequently a reduction in general vigor, and sterility in the female (pp. 1333, 1[3]36, and 1339).

Probably the greatest contribution of the science of genetics to practical breeding has been the formulation of a definite system of inheritance. This system furnishes the basis for a rational approach to breeding problems. However, at present it is difficult, for several reasons, to make specific recommendations on many practical problems confronting the dog breeder—the breeder’s aims are extremely diversified; the dogs themselves exhibit such tremendous variations; there are not nearly enough known facts on inheritance in dogs to solve most of the problems of practical importance; and many practical men have not yet familiarized themselves with general genetic principles. (The discussion of these principles in introductory articles in this Yearbook will probably be found helpful in this connection.)  This emphasizes the need for encouraging research on inheritance in dogs and for organizing breeders so that they can obtain information with regard to specific problems and can at the same time contribute to the knowledge of inheritance in dogs from their own records.

One method of encouraging improvement in the animals themselves would be to offer prizes at dog shows on the basis of the breeding record of an animal instead of almost wholly on the basis of its individual appearance or performance. Genetics has very definitely shown that in many instances the appearance of an animal is not a reliable basis for judging its value as a breeder. Its real breeding value depends on its ability to pass on desirable characters and combinations of desirable characters to its descendants. Because of the effect of dominant genes, the appearance of an animal may give no hint of the presence of recessive genes for quite opposite characters, more or less covered up by the dominants. Thus a short-legged dog may carry the gene for normal legs, which would show up in some of his descendants if they received the same recessive gene from the other parent. Similarly, a black dog may carry the gene for liver color. (See pp.1334 and 1337.)

Not only individual genes but the particular. combination of genes that an animal inherits also determines its appearance or performance.  Since most animals are very mixed in their inheritance, they are capable of transmitting a large number of different combinations of genes to their offspring. For example, a dog of intense agouti or wild gray color without white spots may carry the genes for dilute coat color, for nonagouti, and for piebald white spotting. When this dog was mated with an animal of similar mixed genetic composition, one would expect, if agouti, intense coat color, and absence of piebald white spotting are considered to be completely dominant, ⁵ to get puppies of eight different types so far as appearance is concerned, provided enough puppies are produced: (1) Intense agouti without white spots, (2) intense agouti with white spots, (3) intense nonagouti without white spots, (4) dilute agouti without white spots, (5) dilute agouti with white spots, (6) intense nonagouti with white spots, (7) dilute nonagouti without white spots, and (8) dilute nonagouti with white spots. These 8 types could represent as many as 27 different combinations of genes, considering only the characters mentioned.  Examples of the effects of certain combinations of genes for color are given in the appendix (p. 1343). In many cases there are no data on the results to be expected from given combinations.

This illustrates the fact, well known to geneticists, that often the only way to judge what an animal does carry in its inheritance is by a sufficiently extensive progeny test.

Genetic studies indicate that color, type of hair, length of legs, form of head and body, and many other characters can be transferred from one breed to another by cross-breeding. It is undoubtedly by cross-breeding followed by selection that much of the variation in dogs has come about. New mutations—sudden changes in the germ plasm, later passed on in inheritance—were undoubtedly transmitted to different breeds by cross-breeding and greatly increased the number of types. The large number of types in turn allowed great leeway for selection and the development of still different forms. Many mutations are decidedly disadvantageous to the animals possessing them— so much so that under wild or primitive conditions they may not survive. Under the conditions of domestication, however, many of the mutant types not only survive, but may be superior for certain of man’s uses. For example, certain inherited characters possessed by the Russian Wolfhound give him greater speed than the wolf so that he is useful for hunting wolves. On the other hand it is doubtful whether the Russian Wolfhound could compete successfully with the wolf in the wild state because he possesses certain other inherited characters that would put him at a disadvantage, such as a less well- developed sense of smell and a type of intelligence that is not quite so well adapted to self-preservation as that of the wild animal. Reports (5, v. 1, p. 38) of dogs that have returned to the wild state—feral dogs—indicate that their descendants are often wolflike in form.

If one were to undertake a comprehensive genetic program on the inheritance of many of the characters that make dogs useful, a system of measurements of these characters would have to be worked out so that accurate comparisons could be made. At the present time dogs are used in competitive trials of various kinds, out of which certain measurements have been developed. Generally, however, these tests are of a sporting nature and chiefly measure the ability of the animal to win over its opponents under the particular conditions of the trial.  Often they measure several distinct characteristics. Thus a winning combination must generally include a strong desire on the part of the dog to succeed, excellent morphological and psychological adaptability, a high degree of coordination of physical and mental powers and often a high degree of intelligence, and perfect cooperation between the dog and his trainer or handler.  While such things are often only crudely differentiated or measured in competitive trials, nevertheless, such trials have been a very important factor in the development of breeds especially suited to certain types of competition. The following brief descriptions are given to illustrate what has been done in this connection as well as because of their general interest to dog breeders.

Dog racing has been on the increase in the United States since the devising of a mechanical rabbit for the dogs to chase. The first track using this invention was opened in 1919 in California.  In 1935 meets were held in Arizona, Arkansas, California, Florida, Massachusetts, Minnesota, New York, Ohio, Oregon, Pennsylvania, Texas, and Washington. American racing records taken from the All Sports Record Book (42) are given in table 1.

These records are not quite so fast as the best time reported for running horses on oval tracks—three-eighths of a mile in 33½ seconds, seven-sixteenths of a mile in 39 seconds, and one-half mile in 46 seconds. Mick the Miller, a British dog, considered the world’s fastest Greyhound, has a record of 600 yards (a little less than three- eighths of a mile) in 34 seconds, which compares very well with the best running-horse record for approximately the same distance.  Perhaps a clearer idea of how fast this dog was traveling may be gained from stating the rate as an average of 36 miles per hour for a distance of 600 yards.

According to Menke (42), Mick the Miller is said to be the most intelligent of greyhounds and showed uncanny ability in getting clear of “jams” in the running of races, thus giving him undisputed passageway. From 1929 to the end of 1931 he won $50,000 in purses and numerous cups and trophies. He was 9 years old in 1935, retired and quartered at Walton-on-Thames for breeding purposes even though his exact ancestry was unknown. The increase of track racing in this country has resulted in the importation of thousands of Greyhounds from England and Ireland and the crossing of these dogs with American Greyhounds.

Another form of racing requiring a very different type of dog is dog-sled racing. The most famous of these races are run in Canada and Alaska—for example, the Eastern International Dog Sled Derby run annually over a 120-mile course at Quebec; the Hudson Dog Sled Derby (generally called The Pas Derby) run over a 200-mile course from The Pas, Manitoba, to Flin Flon and return; and the All-Alaska Dog Race at Nome. Similar races have been run in New Hampshire, in upper New York State, and from Winnipeg, Manitoba, to St. Paul, Minn. As the races are run on scheduled dates regardless of the weather, there is considerable variation in the time required by the winning teams. Thus, over the 200-mile course at The Pas Derby the time has varied from 24 hours 51 minutes in 1922 to 37 hours in 1929.  Alaska’s Borden marathons run over a course of 26 miles 385 yards, has been won in time varying from 1 hour 50 minutes 27 seconds to 3 hours 35 minutes. Albert Campbell, a Cree Indian, drove his team of six dogs 522 miles in 118 hours 16 seconds to win the Red River International Derby from- Winnipeg, Manitoba, to St. Paul, Minn. Rules governing the contests vary with regard to the number of dogs allowed per team, whether the race must be run in laps, and other points.

Because of their remarkable strength and endurance, Huskies have been very successful in these dog-sled races. These dogs are the result of crossing Eskimo dogs, which probably have considerable wolf inheritance, with such breeds as Great Dane, Newfoundland, or German Shepherd. It may well be that at least a part of their superiority in strength and endurance is an expression of hybrid vigor. Deerhounds have been used in recent years in crosses with the Eskimo dogs, but though the offspring are big, rugged animals, it is said that temperamentally they are more of a hunting-dog than of a sled-dog type and so are not such useful draft animals as some of the other cross-breds. Greyhounds are also said to have been tried in crosses with the Eskimo dogs. The offspring have superior speed but lack the ability to withstand the severe climatic conditions under which the sled races are often run. Today it is hard to find pure Eskimo dogs in the North as the Eskimos themselves prefer the stronger cross-breds.

Field trials for dogs are now widely held in the United States and in some other countries, notably England, to test the ability of bird dogs such as Setters and Pointers. These trials are actual hunting contests in which the dogs are scored by judges for their ability to locate the birds by scent, to point in the direction of the game, to hold the point until the hunter fires at or flushes the birds, to retrieve the game when crippled or killed, to cover a large area both rapidly and efficiently, and to demonstrate endurance, tractability, style, and perseverance. Generally the competition is divided into three classes, puppy, derby, and all-age, the division depending on the age of the dog. ~ Contestants are run either singly or in pairs.

Similar trials are also being run for Retrievers and Spaniels. In these, the animals must work both on land and in the water and more attention is paid to retrieving the game and less to pointing. Field trials with Foxhounds, Bloodhounds, and other types of sporting dogs, as well as ratters, are sometimes held, and there seems to be a growing interest in them.

One of the effects of these trials has been a decided tendency to develop two strains within some of the breeds involved, one being bred to meet the requirements of field trials and the other to meet bench-show requirements of the fancier or the standard set up by the breed association. In the first strain, mental aptitudes and physique are stressed, and in the second, body conformation and color. A good example of this is to be found in English Setters, in which the Llewellin strain has been very successful in the field, while the Laverack strain has been most noted on the bench.

The herding of sheep by dogs goes back to prehistoric times, though, of course, organized sheep dog trials such as are held today in a number of countries to determine the ability of the dogs in competition are of comparatively recent origin. In Germany organized trials were held about the beginning of the present century.  In 1873 the first sheep dog trial was held in Wales. Since the World War, these trials have become very popular in Great Britain and are also held on a large scale in Australia. In the United States for the last 9 years a sheep dog contest has been held annually in New England and exhibitions are given at a number of fairs and livestock shows.

So far the trials in the United States have been of the type held in Great Britain. One dog is run at a time and is directed entirely with whistles and gestures by the master. Scores are given for the manner and style with which the dogs handle the sheep. Trials are held in a meadow, with the sheep being liberated at one end while the dog and shepherd enter at the other. The dog is then sent out to gather in the sheep, which he must bring to the shepherd. Then he must drive them through a number of hurdles and finally into a small pen in the open field. In some contests the dog is also required to cut out or “shed” a certain number of marked sheep from the flock.  All of this must be done within a certain time limit, without hurrying the sheep, and always with complete obedience to the shepherd’s commands.

Practically all the dogs entered in the contests in Great Britain or the United States are Border or Working Collies. These dogs generally have long black and white coats and are somewhat smaller than the Collies seen at dog shows. Their heads also are somewhat broader and shorter than those of the show Collies, which have been selected for long, flat, narrow-type skulls. Scotch and English shepherds train their dogs not to bite the sheep but only to bluff them, while in Germany, where the dog must often protect the crops from the sheep, the shepherds train the dogs to grip the sheep if necessary. Border Collies seldom bark, which 1s an advantage under the conditions prevailing where they ordinarily are used. In brush country, however, a barking dog can be heard by the sheep when he cannot be seen and is thus often more successful in his work than a quiet one. In some countries, the sheep must be protected from wolves and other wild animals so that large and powerful dogs are needed. Because of these differences in requirements and training, it is not to be expected that the more than 40 varieties of herding dogs, including such varied breeds as the German Shepherd, Aftscharaka, Kelpi, Puli, Old English Sheepdog, Komondor, Bundas, Riesenschnauzer, etc., can compete satisfactorily in trials designed for the Border Collie alone.

In former years some breeds of dogs were bred to fight each other in the pit or arena or, as in bullbaiting, to fight a bull. This kind of competition has largely been outlawed, and the fighting breeds— Bull Terriers, Bulldogs, and Boxers—are now kept largely as companions and guards.

Some of the recent dog shows have been featuring a new type of contest called an obedience trial in which prizes are awarded on the obedience of each animal to a number of commands. Poodles have been outstandingly successful in these competitions.

Of the organized competitive activities connected with dogs, the dog shows attract the most interest. In 1935 there were, according to Menke (42), 2,760 bench shows in the United States, with 200,000 entries and 1,000,000 paid admissions. No one knows how many dogs there are in the United States, though a rough estimate would be between 10,000,000 and 12,000,000. There were registered with the American Kennel Club in the single year of 1935, 72,000 dogs that were eligible for shows.

The largest dog show in the United States, the Westminster Dog Show held in Madison Square Garden, New York, N. Y., had a record in 1935 of 2,837 entries with 85 breeds represented. This was the fifty-ninth Westminster Dog Show held under the auspices of the American Kennel Club and it drew entries from all over the world.

As is the case with other domestic animals, the dogs that can win highest honors in competition either in field trials or bench shows, usually attract the breeders, and dogs that can transmit their ability to win soon become the foundation animals of a strain or breed. Thus the sires Gladstone and Count Noble, which produced 25 and 30 field- trial winners, respectively, are to be found in the ancestry of most field- type English Setters in the United States.  Dog shows also have been one of the most potent influences on breeding in the last half century.  By fostering the adoption of breed standards and the use of these in judging they have kept before dog breeders fairly definite aims to be attained. They have also been a most efficient medium for advertising those animals that, in the opinion of the judges, were the best in their respective breeds and have helped to spread information and interest in dog breeding. The standards, of course, have often been largely influenced by changing fashions and frequently have little or no relation to utility.

On the whole this use of bench-show or field-trial winners as breeders has made for progress, although the overwhelming emphasis on individual performance has also sometimes perpetuated and spread through the breeds defects carried by the foundation stock. The ideal condition for the progress of the breeds would be to place the emphasis on breeding records, which should include all the offspring of a given animal instead of the winners only or at best the offspring without serious defects. Thus breeders would have a progeny test that would indicate the real genetic constitution of a given animal.

The American Kennel Club (3), under whose auspices most of the dog shows are held, included descriptions and standards of 102 breeds of dogs in their book Pure-Bred Dogs published in 1935. These breeds, together with their color, size, and principal uses, for the most part as given in Pure-Bred Dogs, have been listed in table 3. This table clearly indicates the variety of dogs in the United States. It is impossible, however, to give an adequate amount of detail, and for more complete information the readers should consult the American Kennel Club’s publication.

The improvement of dogs along certain practical lines by the use of a knowledge of inheritance appears to offer definite promise for the future. Thus the relative number of German Shepherd dogs that are suitable as guides for the blind or for police or army work can be greatly increased by meansof selective breeding and the application of genetics ashas been demonstrated at Fortunate Fields(22). Also, working ability can be successfully combined to a considerable extent with show form according to the results obtained by the same organization.

Superior hunting dogs may be bred for certain conditions as was done by Adametz (see Iljin (25)), who crossed English Pointers to German Pointers to produce a rapid-working dog that could stand the heat on the steppes of Moravia.

Improved physical and disciplinary traits can probably be secured from certain crosses. Iljin (25) states that in several regions of the Union of Soviet Socialist Republics German Shepherd dogs and Doberman Pinschers are crossed for that purpose.

The histories of a large number of the present breeds as given by the American Kennel Club (3) indicate that they originated from matings between animals of two or more breeds made purposely to combine certain desirable characteristics in one strain.

Doubtless many abnormalities or defects, such as cryptorchidism, cleft palate, reduced larynx, certain types of periodic eczema, etc., can be eradicated or controlled through breeding as indicated by the work of Koch (28). Studies on the inheritance of resistance to infectious diseases with other species of animals, as the mouse, rabbit, guinea pig, and chicken (see Hill (20) for a review of the subject) would indicate that it may be possible to develop strains of dogs with high resistance to certain of the infectious diseases, such as distemper.

In addition to the improvements that might be made in the dogs themselves, undoubtedly studies of the inheritance of various characters in dogs would aid in a better general understanding of mammalian genetics.

That dogs have been used extensively in anatomical, physiological, and psychological research, as already indicated, but to a very limited extent in genetic research is probably due to a number of reasons.  (1) Research workers in the fields mentioned have been able to utilize dogs from city pounds and cheap animals of nondescript breeding, whereas in making a genetic analysis a large number of animals would have to be produced from specific matings.  (2) In studying the inheritance of certain characters, notably psychological traits, for the study of which dogs are especially good subjects, methods of measuring many of the characters must first be perfected before genetic studies will be very fruitful.  In the last analysis, however, probably the principal reason why less attention has been paid to genetic research with the dog has been the feeling that results promising greater immediate economic gain were to be had in other fields.

Yet within a single species dogs show so wide a range of intelligence and temperament that they are better adapted for studies of the inheritance of these characters with the crude methods now available than other species in which the differences are less marked, such as guinea pigs, rats, mice, rabbits, and poultry. Dogs also reproduce with reasonable rapidity and would not be so expensive to maintain in sufficient numbersunder laboratory conditions as horses, cattle, sheep, goats, and swine.  Thus the use of dogs as subjects in certain fields of genetic research appears to offer the most practical means of attacking certain very important problems.

The Bureau of Animal Industry has just initiated a project to study the inheritance of intelligence and associated characters in farm animals with especial reference to the influence of such characters upon performance and production.  Dogs are being used in the early phases of these studies because they probably exhibit a greater range in temperament and in intelligence than most animals; different breeds have been developed for widely different purposes and some of them have important agricultural uses.

In this project dogs of several breeds of different temperament will be subjected to certain tests to determine the range and type of intelligence and their suitability for various purposes, especially for the herding of sheep.  Crosses also will be made between breeds and similar tests will be made on the offspring of the first generation and later generations following the cross.  One of the breeds being studied is the Puli.  Four individuals of this breed (fig. 4) were recently imported by the Department from Hungary. These dogs are noted in their native country for their sheep-herding ability. Studies on this breed and its hybrids from crosses with several other breeds are now under way.

Figure 4.—Puli bitch. One of four animals of this breed recently imported by the United States Department of Agriculture from Hungary for use in studying the inheritance of intelligence and related characters in animals. The Puli has the reputation of being an exceptionally good herding dog in its native country. The most favored colors are white, cream, gray, and black.  Dogs weigh about 30 pounds, bitches about 25 pounds.

From these experiments facts will be secured on (1) the degree to which intelligence is inherited, (2) the manner of its inheritance, and (3) the influence of intelligence, temperament, and certain other psychological traits upon certain special aptitudes of the dog. The experiments will also furnish fundamental information on the type of temperament and psychological traits that are needed in dogs for special purposes. Furthermore, information will be secured on the relation of various types of temperament to such things as feed utilization, appetite, management, and growth. The results obtained from these experiments are expected not only to furnish information on these functions in dogs but also to be of value in pointing the way for further investigations of this nature with other farm animals.

 (1)   ANONYMOUS. 1917. THE HAIRLESS DOG. Jour. Heredity 8: 519-520, illus.
 (2)  Allen, G. M. 1920. DOGS OF THE AMERICAN ABORIGINES. Bull. Mus. Compar. Zool. (Harvard Univ.) 63: 431-517, illus.
 (3) AmericaN KenneL CLus. 1935. PURE-BRED DOGS; THE BREEDS AND STANDARDS AS RECOGNIZED BY THE AMERICAN KENNEL CLUB. 640 pp., illus. New York.
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Figure 5.—Haired and hairless Mexican dogs from the same litter.  (Photograph by courtesy of the Journal of Heredity, after Stockdale (1).)


Color Inheritance

Figure 6.  Collies showing the effects of the genes V—v for dominant spotting (merle dilution): A, Normal black and tan Collie (vv); B, blue merle Collie (Vv), which happens to have both eyes normal, but often one or both eyes will be wholly or partly of a pale bluish-white color—“wall-eyed"; C, merle Collie with defective sight and hearing (VV). Since blue merles or sable merles are mixed (Vv), they will not breed true - when mated together. (Photographs by courtesy of the Journal of Heredity, after Mitchell (43).)



Figure 7.—Foxhounds showing the absence and presence of ticking, colored hairs intermingled with white hairs on those portions of the body that would otherwise be white: A, Foxhound bitch without ticking (tt); B, Foxhound dog with ticking (Tt).  Eight of the fifteen offspring from the above animals were ticked. (Photographs by courtesy of the Journal of Heredity, after Whitney (62).)