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Understanding Dog Sexual Behavior

Prepuberal Sexual Behavior | Masturbation | Heat Period | Copulation | Sexual Foreplay | Sexual Liaisons | Sexual Dreams | Bestiality | Effect of Spaying and Castration on Sexuality | Sexual Inversion and Homosexuality | Satyriasis, Nymphomania, Frigidity | Conclusion

Suppose I told you that a dog does not have a sex life? You— who are an old observer of dogs on the prowl—would prob­ably suggest that I must be slightly off the beam. And yet, that is exactly what I am going to tell you.

We really cannot consider the dog sexual behavior in the same sense that we consider the sex life of human beings. In the strictest meaning of the term, it must be said that a dog does not have a sex life at all. The very least that a sex life seems to imply are a freedom of choice of sexual partner; a certain regularity of sexual routine; and a conscious direc­tion, anticipation, and planning of future sexual activity. While it may be said that a stray or free-roving dog does have relative freedom of choice and also a blatantly immodest regularity in this regard, the likelihood of conscious direc­tion, anticipation, and planning of future sexual activity is rather remote. House pets or breeding animals are even de­prived of the freedom of choice or of any consistent regular­ity, for these animals are permitted to engage in sexual ac­tivity only at the whim and fancy of the individual owner. Therefore, while it may be said that a dog does not have a sex life, properly-so-called, it certainly cannot be denied that a dog engages in sexual activities. It is the purpose of this chap­ter to consider some uncommonly discussed aspects of the dog sexual behavior from the standpoint of the ran­dom observations and casual reading of an ordinary veteri­nary practitioner. It must also be added that, while I do not

intend to offend the sensibilities of dog lovers, some observa­tions on the cat will also have to be included whenever speci­fic parallel data on the dog cannot be given. This has to be done because the cat has sometimes been more amenable to certain kinds of experimentation on sexual behavior. None the less, both dog and cat can teach us something about the sexual behavior of one another. We have no alternative but to take our basic information wherever it happens to be available.

An animal activity is said to be instinctive when the ac­tivity is performed perfectly, from the very first time that it is done, without any previous learning. All activities that re­quire learning before they can be performed well cannot be said to be instinctive. Thus a beaver builds a dam by instinct; ants build their hills by instinct; homing pigeons return home by instinct, and so on. But man learns to drive a car, to fly a plane, to play the piano. He emphatically does not perform these activities instinctively. In addition, there are some ac­tivities that are only partly instinctive since some learning is required to bring them to full fruition. Sexual activity in the dog is one of these.
Sexual activity in the dog is partially instinctive and par­tially learned. It is instinctive to the extent that it is an un­learned, fundamental, biological impulse. It is not instinctive insofar as some learning is required to render that impulse functionally adequate. In primitive animals that are far be­low the evolutionary status of the dog, sexual activity is purely instinctive in nature. Upon reaching puberty, these lower animals carry out their sexual functions to utter per­fection without any learning whatsoever. The sexual impulse in these lower animals is perfectly and completely inherited. In dogs, on the other hand, the sexual impulse is only imper­fectly inherited, and a certain amount of learning is required in order that those sexual activities necessary to the propaga­tion of the species be adequately carried out. This seems to be more evident in the male than in the female.

In its prepuberal  life that is, in the period before sexual maturity the female dog never exhibits any of its adult sex­ual patterns, but when it attains puberty it carries out its sex­ual functions, from the very beginning, with an admirable competence. The male, on the other hand, exhibits an abundance of its adult sexual patterns in its prepuberal  existence. It mounts its companions in typical, male mating fashion, indulges in pubic thrusts and convulsive pubic move­ments, and seems to make every effort to learn to prepare it­self to become a male adult. None the less, upon reaching puberty, it ordinarily carries out its sexual functions with an extreme awkwardness and seems to require at least a modest amount of sexual experience before it can become an effec­tive partner in the sexual act.

These observations suggest that sexual activity is more of an instinctive manifestation in the female than it is in the male; that is, that learning is required in the male to support its instinctive sexual impulses, whereas it does not appear to be required (at least not to such a degree) in the female. This conclusion is further supported by experimental evidence in studies on the brain of the dog. The portion of the brain that is concerned with higher intellectual functions, such as learning, memory, imagination and the like, is called the cerebral cortex. If this portion of the brain is removed, these intellectual functions cease to exist. Now when it is removed from the dog, the female continues to engage in its normal sexual activities while the male exhibits no sexual interest whatsoever. The implication is that learning is essential to the sexual behavior of the male dog and not to the female. This fact also helps to explain why male dogs commonly show greater discrimination in the choice of a sexual partner than a female at the highest point of heat, and also why males are more apt to be sexually disturbed than females by sudden changes in the immediate area where the sexual ac­tivity takes place. The role of the female in sex being essen­tially passive, when she is in heat she is simply ready for the acceptance of the male. But the role of the male is essentially active and he must always be ready for the female who comes in heat. The male must achieve and maintain an erection. This fact, along with the cerebral connection of the male with sex, makes it logical that the male requires the more favorable situation for achieving sexual completion and that it can be readily disturbed by unfavorable circumstances. It is apparent, therefore, that while the sexual impulse has an instinctive basis, a certain amount of learning is required to render that impulse functionally adequate.

The question may be rightfully raised at this point why a higher animal should inherit an instinct less perfectly than a lower one. Since there are certain functions that are essential to life, should not a higher animal inherit the predispositions to these functions even more perfectly than a lower one? Why should the opposite be the case? The reason for this appar­ent inconsistency is that it is one of the ways in which the pro­gressive mental evolution of animal species from lower to higher forms was rendered possible. Whereas lower animals inherit their instincts to absolute perfection so that life's ac­tivities can be adequately carried out without any form of learning, these instincts become increasingly less perfectly inherited the higher the animal progresses in its evolution­ary development. The logic of the process is simply this: if the instincts necessary to survival were always perfectly in­herited, there would be no need for further mental develop­ment. All of life's problems could be satisfactorily met on an instinctive level. Where instincts were only imperfectly inherited, the animal world was stimulated to exercise its mental capacities in order to cope with the problems of life. In this way, the less perfectly inherited were the instincts, the greater was the necessity and the possibility of further men­tal development. There are, of course, additional factors in the stimulation of evolutionary mental development, but the way just described was very likely of very considerable im­portance.

However imperfectly these instincts were inherited, they still persisted. They were apparently necessary for the con­tinued survival of the species. And since they were imperfectly inherited, they had to be supplemented by learning in order to bring them to full fruition. If this did not occur, the species was doomed unless some drastic and favorable change in the inheritance pattern took place. Sexual behavior in the dog exemplifies rather typically how learning supple­ments an imperfectly inherited sexual impulse.
In the interpretation of animal sexual activity, we have no way of probing into the conscious or subconscious mind of the animal to determine whether its behavior is subjectively sexual. We can only watch the way the animal behaves, and where that behavior involves the sexual organs in a sexual way, we have to consider that that activity is sexual behavior.

Prepuberal Sexual Behavior

Dog sexual behavior seems to start at a considerable age before puberty. Puppies of either sex, as young as three months of age and sometimes younger, have been noted to mount each other in male copulative fashion and to engage in suggestive sexual movements. Both male and female pup­pies exhibit the male pattern of adult sexual behavior. It is significant that the female pattern of adult behavior is never exhibited by the female prior to puberty. The reason for this phenomenon has been attributed to the fact that male sex hormones appear in both males and females very early in the puppyhood stage, while female sex hormones do not appear until puberty. But this hormonal explanation is inadequate. While it can, to a certain extent, explain the male pattern of the female puppy, it cannot apply to the male because cas­trated puppies will behave in a similar manner. It is generally considered that this activity in prepuberal  dogs assumes the nature of play. But why should play in puppies often exhibit this frankly sexual form?

The problem of animal play  is one that has intrigued many astute investigators. During the last century, Herbert Spencer promulgated the "Surplus Energy Theory  of Play," which stated that play was a manifestation of sheer exuber­ance and a way of dissipating excess energy. The theory broke down because it was well known that animals continued to play long after their exuberance was gone. The exhausted dog will still lope to retrieve a stick that is thrown. The pant­ing cat will still take a final swipe at its catnip toy. Animals seem to play, not to dissipate excess energy, but simply for the sake of play. Later, an "Instinctive Theory " was postu­lated, which stated that play was simply instinctive. But this theory also broke down because it could not adequately ex­plain the special forms of activities that were manifested in play. It could not explain sexual play or fighting play or hunting play. The theory currently generally accepted is the so-called "Biological Theory of  Play," which states that play is the necessary prelude of prepuberal  animals to prepare them to meet the problems of life. Animals do not play be­cause they are young and frolicsome, but rather have a pe­riod of youth in order to play. In this period they learn to hunt, fight, protect themselves, and so on. The higher the mental development of the animal, generally speaking, the longer will be its prepuberal  period because it simply needs more time to learn the many things that are necessary in order to cope with the problems of life. From this point of view, the frankly sexual play of dogs would seem to be noth­ing more than a youthful preparation for later requirements in life.


Masturbation rarely if ever occurs in the normal prepu­bera l or adult female. Of course the female can be stimulated to lick its genitalia where local irritations of the external geni­tals occur, but this cannot be properly considered a sexual activity. In the male, on the other hand, masturbation occurs rather early in the puppy. It is performed by licking the penis or by rubbing against soft objects that can be conveniently grasped in a sexual embrace. It is rather common in puppies of about five or six months of age, and often continues throughout the adult life. Reliable scientific information re­garding masturbation in the dog is notably lacking, though even the most casual observation will reveal its undeniable presence. It is common in males just prior to and upon the completion of copulation . Some dogs, especially those that are bored, left alone a great deal, or those that upon matur­ity have little opportunity for sexual intercourse, may develop the masturbation habit. Of course masturbation can be en­couraged by any pathological factor that will stimulate the excessive flow of sex hormones. According to my observa­tions, the masturbation habit in the dog is not ordinarily ac­companied by outward physical symptoms that are detri­mental to the health of the animal. To my knowledge, psy­chological effects of masturbation in dogs have not been criti­cally examined, though clinical observation seems to indicate that these effects are not especially significant. It is very un­likely, however, that the male masturbating dog conjures up any exciting mental image of the female while engaged in this activity. What is most likely is that masturbation, in this instance, is a purely stimulus-response manifestation. The maturbatory act may be stimulated, for example, simply by licking some penis discharge. This, in turn, may stimulate the animal sexually and the act is carried through to its completion. The important point is that masturbation in the dog is apparently not consciously directed to sexual self-stimulation. The stimulus that initiates it is only incidental and not necessarily sexual. For the act to be considered gen­uinely masturbatory, both stimulus and response must be sexual. Where the stimulus is not exclusively sexual—as is the case with the dog—the most that can be said is that we are dealing with a mere masturbatory activity rather than a truly masturbatory act. Nor is masturbation in this sense "abnormal" in the dog. If a dog is properly stimulated it will "masturbate." Thus masturbation is a normal activity in dogs.

Heat Period

The heat period of females was discussed in the chapter, "Pregnancy and Breeding." However, it will be well to add the less well-known fact that the onset of heat is related some­how to the lengthening of the day. Under experimental con­ditions, the period when the dog is not in heat can be sub­stantially shortened by subjecting it to abnormal exposures of artificial daylight. Just what specific reaction is involved here is not known, but it is very likely that this fact accounts for the variability of heat periods in dogs in different parts of the world.

Another fact of interest in this connection is that if a cat in heat is not bred, it will remain in heat for several days. If it is bred successfully, it will often lose its responsiveness in about twelve hours.


The act of copulation  in cats lasts about five to ten seconds. With dogs, on the other hand, the duration is much longer because genital "locking" occurs. This genital "locking" is quite normal in dogs and after ejaculation the animals will separate without assistance in anywhere from a few minutes to a few hours, with the average time being about twenty min­utes.

It may be amusing to note that the longest matings in mam­mals occur in the mink and sable. These animals do not lock but, once entrance into the female is achieved, it is main­tained for very long periods. Several ejaculations seem to take place and there are rest periods in between. From the moment of original insertion until withdrawal, the sable has been timed to copulate for as long as eight hours.

In regard to the frequency of copulation , some male cats may copulate nine or ten times in an hour. Others may copu­late four or five times before their sexual responses are subdued. In these instances, each copulation  includes an ejacu­lation. Male dogs, on the other hand, rarely copulate more than once an hour providing copulation  is complete and sex­ual locking occurs. This situation has a logical physiolog­ical basis. The cat, after all, must undergo intercourse as a stimulus for the expulsion of the ovum. The female dog ex­pels its ovum naturally without the necessity of any additional stimulation. Thus it is not surprising that the cat copulates more actively than the dog.
Though the upper limit of the responsiveness of the female dog has not been subjected to scientific tests, we can be pretty sure that it exceeds that of the male. When female cats are kept in heat artificially with hormone injections, they copu­late continuously and exhaust one male after another.

Another interesting fact is that a pregnant cat will some­times permit an active male to have intercourse with her. But this behavior is irregular and unpredictable.

Sexual Foreplay

The essential difference between human sexual foreplay and that of the dog is that, unlike the animal, sexual foreplay in the human is consciously directed toward sexual stimula­tion. A male dog may lick the external sexual organs of a female in heat because it is attracted by the female discharge and its odor, but it does not perform this activity because it feels that it will excite the female. It acts, rather, as if it is merely investigating the area. But the fact is that its behavior does excite the female and excites the male too. In this man­ner a lusty male can stimulate a sluggish female in heat and achieve a mating. In the same way, a female in heat may sniff at or lick the male organs and may thus excite a slug­gish male to become more aggressive in his mating responses. A female may also mount a male in the male copulative fash­ion and this activity often seems to stimulate the male.

When a male cat is about to have intercourse with a female, the torn first grasps the loose skin of the female's neck in his teeth. This action seems to have three results: it produces an erection in the male; then the female lowers her fore quarters and gets into the mating position; lastly, by maintaining the grip after it has mounted, the male can more readily get into the proper position so that genital insertion can result. A male cat will rarely succeed in completing the copulatory act unless it grasps the female in this way.

Some dogs may be sexually stimulated merely by being placed in a situation where they had previously experienced intercourse. This is especially true if a breeding crate is used. There can be little doubt that sexual stimulation here is a con­ditioned response.

Sexual Liaisons

Mateships, as exemplified by human marriage, are con­sidered to be lasting sexual unions. Liaisons are temporary or casual relationships. The best that can be said of the dog is that it is an occasional party to what may be very liberally interpreted as a sexual liaison. This is more the result of cir­cumstances than of preference. One occasionally hears of a male and female brought up in the same household who seem to develop a genuine affection and exclusive sexual prefer­ence for each other. But this is the exception rather than the rule. All that can be said for sure is that dogs show a certain amount of discrimination in the choice of sexual partners, and males do so to a greater extent than females.

Sexual Dreams

Not only does every indication point to the fact that dogs dream, but there is further evidence that they also have sexual dreams. Pelvic thrusts with nocturnal emissions have been observed in both male and female dogs and cats. Just how much "imagination" goes into these dreams poses an interesting and challenging psychological problem.


Sexual relations between animals and men is as old as time. There are and have been sexual relations between dogs and humans; almost every conceivable position and manipu­lation that can be conjured up by the lasciviously brisk imag­ination has very likely already been attempted. In such re­lationships the dog often transfers its sexual affections to the human being directly involved. A dog that is habitually mas­turbated by a human may transfer its sexual affections to that human to such a remarkable degree that it will cease to be receptive to females of its own species.

Sexual relations between dogs and species other than the human have also been reported. Captive female baboons that South African farmers keep chained to stakes frequently offer themselves sexually to dogs. Ford and Beach, to whom we are indebted for much of the information in this chapter, tell of a case of a female macaque (a type of monkey) that copu­lated repeatedly with a male dog. Copulation was performed dog fashion, the dog attaining partial entrance into the female and causing great sexual excitement in the macaque. The macaque would copulate with the dog whenever it en­tered the monkey's yard. On a later occasion, the monkey of­fered itself to a strange dog, but this animal bit off the macaque's arm. Since then, all the monkeys of the herd have shown their hostility to dogs.

Effect of Spaying and Castration on Sexuality

Spaying promptly and permanently abolishes all sexual behavior in female dogs. These animals possess no attrac­tion for males of their species and never display sexually re­ceptive behavior. The male dog that is castrated before pu­berty never develops the normal degree of sexual aggressive­ness. However, these males do show a certain amount of sex­ual activity. They may exhibit abortive attempts to mount others and may display a few weak pelvic thrusts. Prepuberally castrated dogs develop nothing more intense than the normal, prepuberal  sexual behavior.

The male, castrated in adulthood, however, often shows very little decline in sexual aggressiveness. Laboratory ex­periments on adult castrated male cats have demonstrated that there is no decline in sexual aggressiveness in these animals over the period of several years during which they were observed. Some of them seemed to suffer a reduc­tion in the ability to copulate, but none were unable to do so. These observations indicate that sexual activity in female cats is much more dependent on hormones than it is in males.

Sexual Inversion and Homosexuality

From the standpoint of endocrinology (the study of hor­mones and the glands that produce them), no individual is ever totally male or totally female. By definition, a male in­dividual is one in which the male hormones predominate, and a female is one in which the female hormones predomi­nate. It is logical to presume, therefore, that, if some disease process should disrupt this hormonal predominance in either sex, corresponding changes in sexual behavior should occur. Limited though it is, the evidence on hand seems to bear out this contention.

While sexual inversion is rare in male dogs, cases of dogs with cancers of the testicle have been reported in which the affected male seems to undergo a variable degree of feminiza-tion, manifesting itself in seeking to be copulated by other males, being indifferent to females in heat, and even becom­ing an object of sexual desire for normal males. This is the closest approximation to true homosexuality in dogs, that is, to a state in which the sexual drive seems to be clearly di­rected toward achieving sexual satisfaction with a member of the same sex. One French author believes that these testicu-lar tumors  elaborate female hormones or other substances analogous to them that undergo alterations by metabolic processes and terminate in feminization. Still more rarely, feminization is said to come about as a consequence of cer­tain pituitary, adrenal, or thyroid tumors , though specific instances of this casual relationship in dogs have never been brought to my attention.

I am not aware of specific medical cases of the masculini-zation of female dogs. The cases most often mentioned among animals are those of cows, in which these animals assume a remarkable abundance of the physical and mental attributes of the male. The condition is considered to be caused by various tumors  of the ovary or of the adrenal, pituitary, thy­roid, or thymus glands, or it may be a manifestation of an excess of male hormones due to a simple functional variation of these several glands. There is no reason why similar cases should not occur in dogs.

As mentioned earlier, normal female dogs exhibit certain distinctly masculine traits in that they often attempt to mount either male or female in the male fashion. Where this occurs before puberty, it has been suggested that it is very likely attributable to the temporary preponderance of male hor­mone. In mature females, this behavior occurs most com­monly during the heat period and seems to be one of the ways in which an aggressive female arouses an unresponsive male to sexual activity.

Male cats, in the absence of a female in heat, will often seek to copulate with each other. However, if a female in heat should come upon the scene, both males will immediately copulate with the female. These activities are normal for mature male cats. So it would seem that male cats are nor­mally bisexual—that is, that they will readily copulate with either male or female, depending upon which is available at the time that the male happens to be aroused.

In regard to homosexuality among otherwise normal dogs or cats, the most that can be said is that while these animals unquestionably engage in homosexual behavior, it cannot be considered true homosexuality because there is no evi­dence that it is consciously directed to the exclusive attainment of sexual satisfaction in the sense of homosexuality among human beings. A male dog may lick the genitals of another male because of the curiosity aroused by the appear­ance and smell of an abundant penis discharge. This act may sexually stimulate the dog acted upon, but the act itself seems to be in the nature of an investigation rather than a de­liberately sexual move. Male dogs may mount each other in play or even after having been stimulated in the normal fashion by a female. Actual intromission with subsequent orgasm is possible, though most often very unlikely. Fe­males will occasionally lick each other's genitalia, but more as a grooming procedure or out of curiosity than as a sexual approach. The fact that the female acted upon may be stimulated by this procedure is secondary. While the act itself may be classified as a homosexual activity, it does not appear to be homosexually motivated.

The least that may be said, however, is that while true homosexuality does not exist in apparently healthy dogs, some homosexual tendencies exist in all normal dogs, more commonly in the male than in the female. While homosexual­ity in man may often be attributed to psychological malad­justments, this relationship has not been established in the dog. The explanation of homosexual manifestations in the healthy dog is encompassed within the sphere of its normal activities.

Satyriasis, Nymphomania, Frigidity

Excessive desire for sexual activity in the male is called satyriasis. Excessive desire for sexual activity in the female is called nymphomania. Lack of or subdued sexual desire in either sex is called frigidity. These conditions are more com­mon in the dog than is ordinarily imagined. While the causes of these abnormalities in the human are often psychological in character, there is little likelihood of such a causal relation in the dog, though the involvement of these factors is not im­possible. These conditions are most often due to obvious hormonal derangements that are routinely amenable to the pe­destrian hormonal and surgical procedures of every veteri­narian. It is well to be reminded, however, that, because male sexuality is less affected by hormones than the female, hor­monal or surgical approaches will be much less certainly suc­cessful against satyriasis than against nymphomania. The frigid animal may be stimulated with appropriate hormones, but attention should also be paid to proper feeding and to cutting down on possibly excessive breeding, which may also be related to frigidity.


We may conclude this section by reminding the reader that, since experimental data regarding these unconventional aspects of the dog sexual behavior are notably lack­ing, it was unavoidable that interpretations of these activities often had to be fragmentary or conjectural. None the less, it seemed a good idea to summarize briefly the present state of our knowledge in this fascinating field. The least that it may accomplish is that it may stimulate more careful observation of the dog's sexual behavior.

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