A Veterinary "Review" Article on Neutering, with Implications
for Dalmatian Stone-Formers
Carroll H. Weiss
Study Group on Urinary Stones
Dalmatian Club of America
The following is a summary of an article written and co-authored by three graduate veterinarians; it was published in the most prestigious U.S. veterinary journal. Except for reactions to the article's acknowledgement of dwarfed and infantile os penises in prematurely castrated dogs, neither I personally nor the Study Group on Urinary Stones nor the DCA endorse the information. It is summarized and published for your information only.
A "review article" in human and veterinary medical journal publishing is one in which the author(s) condense most or all of published scientific articles on a specific subject from worldwide accredited journals and textbooks. For the readers, the compendium provides in a single published article the current status by authoritative specialists as compared to having to obtain and to read each of the publications.
This abstract is of a review article on the subject of elective neutering and its effects on dogs' body systems and structures. The authors, two of whom have doctorate or masters degrees in addition to their DVMs, summarized over 100 published articles from veterinary journals, veterinary textbooks, journals of humane societies and a spectrum of definitive publications reporting the influence (or lack of in sterilized animals) of sex hormones on skeletal, urogenital and other body systems and their influence (or lack of in sterilized animals) on normal growth and normal maturing. Comments about Dalmatian stone-forming were not in the original article but are those of the DCA Study Group on Urinary Stones; all others are paraphrased or quoted from it.
The article was entitled, "Elective Gonadectomy in Dogs: A Review" by Katharine R. Salmeri, DVM, Patricia N. Olsen, DVM, Ph.D. and Mark S. Bloomberg, DVM, MS. It was published in the April 1, 1991 issue of the Journal of the American Veterinary Medicine Association, volume 198, pages 1183-1191.
Male castration and female spaying appear to have two major advocates: one group who believe neutering can avoid or minimize cancer of the genitals, and a second group concerned with the current overpopulation of pets. The latter group and those who are dedicated to rescue are alarmed by intact dogs indiscriminately being bred or mating thereby increasing the numbers of abandoned dogs. It is these latter groups in which there is growing emphasis to consider early even premature neutering of puppies and litters to eliminate adopted yet still-intact dogs from going out to swell the overpopulation of unwanted animals. (Abstractor's comment: Some Dalmatian puppy sales contracts stipulate spaying-neutering and a few breeders are suggesting patched and pet quality Dalmatians be neutered before the buyer takes possession of the puppy.)
Countering indiscriminate sterilization, no matter how justified in principle, are serious health effects produced by premature neutering. Neutering is the removal of sexual organs and thereby, it must be remembered, the removal of the source of sex hormones and their normal interaction with the equilibrium with other hormones produced elsewhere by different glands. Also removed is the influence of the sex hormones on other body systems such as stunted growth of the skeletal system if neutering is performed too prematurely.
Background:Castration of dogs was reported back in 284 B.C. but effects of neutering on domestic animals have paradoxically been sparsely reported to date. Animal control and rescue operations report a 50 to 60 percent compliance to neuter on the part of people adopting pets. Because so many adopted pets leave shelters intact, by neutering before adoption and thus increasing compliance to 100 percent, routine sterilization is becoming the rationale by some in the rescue community. The authors noted, "Veterinarians, on the other hand, question the safety of 'neuter at adoption policies,' inasmuch as [it] is not routinely performed on young pups and kittens."
Ages at Which to Neuter:In the early 1900s, veterinarians spayed bitches between three and six months of age, some even prior to weaning. Males were castrated as young as four weeks of age.
Today, veterinarians suggest neutering to be done in:
Bitches - spayed between five and eight months
Males - castrated between six and eight months *
* (The DCA Study Group suggests this be extended to 50 weeks of age)
Definition of Animal "Puberty:"If sterilization programs are to be effective in controlling animal overpopulation, the article suggests they must be performed before the onset of puberty and it is here where opponents of premature neutering (the DCA Study Group included) raise objections. "Puberty" is roughly defined as the onset of reproductive capabilities. In bitches, this is the first heat. In males, this is the first appearance of sperm in their ejaculate. Pre-pubertal (premature) neutering is defined as when sexually immature animals are sterilized. The article notes there can be variation in the onset of puberty dog-to-dog within one breed as well as breed-to-breed. In toy breeds, puberty takes place as early as six months whereas in large breeds, as late as 24 months (two years!). These variances make it difficult to establish a guideline age at which premature neutering will occur in the individual dog and in its specific breed.
Influence of castration on Dalmatian stone-forming:The os penis in male Dalmatians is the usual anatomic site of the dreaded (This paragraph is not part of the original article)life-threatening urinary obstruction when a large urinary stone has been moved by the urinary stream and has dammed up at the narrow stricture of the os penis. There, the lodged stone will block the expelling of urine which then has no exit and starts backing up into the Dalmatian's system. Untreated, the reflux of urine can cause death after only a few days. The article affirms that normal growth of the os penis in young male dogs "is regulated primarily by testosterone...." The male genitals and the testosterone they produce continue to influence the growth until the os penis is finally mature at 50 weeks of age. Thus, "...castration prior to completion of growth could result in a smaller than normal os penis." Remembering the frequency of the os penis being the culprit in the dreaded urinary obstruction, it seems to be important therefore to assure the os penis of Dalmatians is permitted to mature and reach its largest size possible in males (all of whom are born with the potential of urinary stone-forming). The DCA Study Group on Urinary Stone-Forming accordingly thinks any owner or breeder of male Dalmatians should be aware premature neutering before 50 weeks of age may result in smaller-than-normal os penises, according to this article.
Influence of sex hormones on the skeletal system:The sudden growth spurt of children as they approach and reach puberty is eloquent evidence of the influence of sex hormones on maturing human skeletal growth. Similarly, menopausal and post-menopausal human females developing osteoporosis is one example of the effect of dwindling sex hormones on their skeletal system. The authors quote articles documenting the influence of sex hormones on the growth, development, maintenance and aging of animal skeletal systems, and the corresponding undesirable skeletal and bone effects resulting from the absence of sex hormones due to neutering.
Influence of neutering on animal obesity:"Obesity has been cited as a specific reason not to spay or castrate dogs," according to some of the references the authors review. In one study of 8,268 dogs, they noted "24.3% of...spayed females were twice as likely to be obese than were sexually intact females, and there was a trend for castrated males to be more overweight than intact males."
Influence of neutering on behavior:"Castration of adult dogs has been shown to reduce roaming behavior by 90%," according to one publication reviewed. Aggression between males also was reduced by castration as well as urine marking inside the house. Interestingly, leg-lifting by males does not require testosterone in the adult dog; it appears to be organized before birth by fetal male sex hormones. Dogs castrated at 40 days were compared during two to eight months of age to their sexually intact littermates in social behavior; no differences were seen in mounting, chasing, growling and playing. Dominance did not appear to be affected by early castration. Mounting behavior by bitches did not depend on the presence of estrogen. Sexual receptivity on the other hand depended on declining estrogen but rising progesterone.
Spaying bitches and secondary sex characteristics:Dermatitis in and around the vulva, and vaginitis, were reported in spayed bitches "...particularly when performed prior to puberty." The vulval skin rash seemed to be more common in spayed females that were both obese and also had an infantile vulva. The vulva of bitches remained infantile when spayed prematurely before the first heat. The article noted "...the vulva, vestibule and vagina will atrophy regardless of the age at which [the bitch is spayed]." Vaginitis in spayed bitches may be more difficult to control.
Castrating males and secondary sex characteristics:Development of male urogenital structures such as the penis and prepuce are dependent on the male sex hormone, testosterone, or its metabolites. Males castrated at birth or at four-and-a-half months, for example, are unable to achieve a tie because of infantile size of the penis [Abstractor's comment: this is sort of meaningless being that the males are castrated]. Adult males, when castrated, showed only mild reduction in penile size. Premature castration in cats was suggested to predispose to ascending urinary tract infections.
Influence of neutering on the urinary system:The authors state "...urinary incontinence... [has] been used as arguments against early neutering." In bitches, spaying has been reported to be associated with an increased incidence of incontinence (of which there are more than one type). One called "stress incontinence" is often seen with neutering and dogs with this type "will have no physical or neurological abnormalities, but will involuntarily leak urine when recumbent or asleep." Incontinence may take weeks to years after neutering to show up. In contrast, the authors note that incontinence can occur in intact animals and is unclear as to its cause. They note there is no evidence that neutering, even prematurely, potentiates the problem but further research is needed to determine its influence on urinary function.
(end of draft of 19-Apr-98)