This partial literature revue about our pets sexual hormones physiological roles, and the consequences, both positive and negative associated to their presence or their deprivation, was published as a reflexion tool, a base for deeper search, and the base of discussions with your veterinarian before you make an irreversible decision direclty related to your pets health. From scientific publications and statistics, many health problems are related to gonadectomy (ovariectomy or castration), and health advantages are also related to it. We have to be aware of those health problems prevalence in our pets in our reflexion, but we also have to keep in mind that gonadectomy is not a harmless intervention, that won't have any negative consequences on our pets physiology. We can easily see that sexual hormones play physiological roles on multiple levels, and that gonadectomy isn't a panacea to all our dogs and cats problems.
We insist on the fact that any medical decision should necessarily be taken with our veterinarian.
A FEW SEXUAL HORMONES PHYSIOLOGICAL ROLES
Precision: in this text, sterilization in female is associated to ovariectomy (ovarian ablation), and sterilization in males is associated to castration (testicles ablation). Gonadectomy consists in gonads ablation. Ovaries in females, and testicles in males.
Sexual hormones are anabolic steroids. The play a role in many organs growth. They increase muscular proteins synthesis. They play an important role in long bones growth (legs...), and later, they inhibit those bones linear growth (1,50). Meaning that dependently of the age at which a dog is sterilized, his/her legs will be either shorther or longer than that they would have been without external intervention. Which doesn't necessarily mean a marked difference, but can cause orthopdic problems, like we'll see later.
Mammals mature red blood cells don't have a cellular nucleus. Because of this fact, they can't multiply. Furthermore, their life cycle being short, they must be constantly renewed (2). Sexual hormones play a role in this renewal, by acting directly on stem cells, and by stimulating erythropoietine production (which stimulates stem cells too) (1,3).
Gonadectomy eliminates the possibility to develop certain health problems related to the reproductive system. Gonadectomy in males eliminates testicular cancer risks. In females, generaly sterilization consists in an ovario-hysterectomy (ovaries and uterus ablation), so it eliminates the risks of developing a pyometra (hormonal unbalance causing a uterine infection which has to be treated rapidly), and it reduces the risks of developing mammary tumors later in life, IF the bitch is gonadectomized before her first heat preferably, or before her second heat (ovariectomy done before the first heat reduces the risks of developing mammary tumors to 0.5% of the risk of intact bitches, and if done before the seond heat, the risk is reduced to 8% of the risk of intact bitches. Bitches ovariectomized after they reached maturity have the same mammary tumor risk than intact bitches (3)).
In the cat, if the gonadectomy is done before the age of one year, risks of developing mammary tumors (carcinoma) later in life are reduced significantly (40).
But, in bitches, if she's gonadectomized before her first heat, she hasn't reached maturity neither physical nor emotional.
Puppies, like humans, go through diverse maturation stages, which are triggered by the sexual hormones production. Many canine psychologists believe that a dog who is deprived from sexual hormones is more inclined to develop inappropriate behaviors, because he/she will never reach the stability associated with maturity. We believe that those immature dogs have a bigger need of stability and to be directed by their human family. Owners who choose gonadectomy before their dog reaches maturity should be aware of the situation in order to prevent behavioral problems, which can be of any level (housebreaking, separation anxiety, aggressivity etc...), by giving their puppy an appropriate education.
Deficiency of hormones produced by testis (testosterone) and by ovaries (oestrogens) can induce urinary incontinence (3,4,5,14,15). This phenomena happens in 20% of gonadectomized bitches (6,52). The cause is not yet well explained, but sexual hormones probably have effects on uretral sphincter (14,15). This problem is more frequent in bitches than in male dogs (3), however, it exists also in male dogs (7). Tall breeds would be at high risk (5,7,52). In a study, gonadectomized bitches who weight less than 20 kg, 9.3% developped urinary incontinence, while in those who were over 20 kg, the incidence was 30.9% (52). Certain breeds are known to have a gonadectomy related urinary incontinence predisposition: 65% of Boxers are affected (5, 6, 52), and Doberman pinschers and Giant Schnauzers have a higher predisposition than average (5, 6). From Blendinger C. and al. (53), the gonadectomy related urinary incontinence incidence would be significantly superior in Giant Schnauzers, Irish Setters, Boxers and Bobtails. It appears certain breeds would be less predisposed. A study shows that 10.6% of German Shepherds and 11.1% of Teckels became incontinent (52).
Until now, studies show that the risk of developping ovariectomy related urinary incontinence is not different if we compare bitches ovariectomized at young age and those ovariectomized after they reached maturity. However, a study showed that clinical signs of urinary incontinence associated with ovariectomy are more important in bitches ovariectomized at young age than in those ovariectomized at a more advanced age (35).
A study shows that ovariectomized bitches have a higher risk than intact bitches, of developping urinary infections, sexual hormones deprivation having an effect on the bladder defense mechanism (13).
Howe et al., showed in 2001, that infectious diseases are more frequent in dogs who were gonadectomized at an early age (before puberty), than in those who were gonadectomized at a traditional age (after puberty) (49).
According to a study, male dogs who were castrated between the age of 8 and 12 years old would be at higher risk than intact dogs, of developping calcium oxalate urolithiasis, along with dogs who are overweight (36). Uroliths are cristals that form in the bladder, causing urinary problems.
Castration doesn't lower risks of developping prostatic carcinoma (cancer) in dogs (27). It appears that castrated dogs would be at higher risk of developping prostatic cancer than sexually intact dogs (26, 54). According to a study, over 80% of sexually intact dogs aged over 5 years old develop a benin prostatic hypertrophy. On the other hand, castrated dogs would have a higher risk than sexually intact dogs to develop prostatic cancer (adenocarcinoma) (16, 26), independantly of the age at which the castration was done (27). Furthermore, in prostatic cancer cases, there would be a higher incidence of pulmonary metastasis in castrated dogs than in sexually intact ones (17).
A study showed that the more frequent prostatic diseases in dogs are in order: bacterial infections, cysts, adenocarcinoma and benin hyperplasia (18). What this study also revealed is that the more frequent prostatic disease in castrated dogs is adenocarcinoma (cancer) (18). The breed at higher risk being the Doberman Pinscher (18). Sorenmo et al. results are similar of those of epidemiologic studies that show that castrated dogs have a higher risk than sexually intact dogs of developping a prostatic carcinoma (44).
A study published in 2007 also shows that there is a canine breed related predisposition to prostate cancer, which suggests a genetic predisposition (57), and it also shows that castrated dogs (from all breeds) have a higher risk of developping prostate cancer (all types) than intact dogs (57).
It seems that ovariectomized bitches have a higher risk of being affected by hypothyroidism, compared with sexually intact bitches (3, 21, 25). And a study showed that gonadectomized dogs (both males and females) have a higher risk of developping hypothyroidism than sexually intact bitches (8).
Studies show that gonadectomized dogs (males and females) are at higher risk than sexually intact dogs and bitches, of having a cranial cruciate ligament rupture (19, 24). A study done in 2005, including 369 dogs, shows that 8% of those patients were sexually intact bitches, for 43% of gonadectomized bitches, and 14% were sexually intact males, for 35% of castrated males (43). The risk being constant, wathever the breed and size of dogs (28).
Gonadectomy can cause dermatitis, including mild alopecia in dogs and cats, but condition is not frequent (3). It can also cause endocrine alopecia in cats, more frequently in castrated males (3).
One of the potential negative impact of ovariectomy in bitches is that dominant ones can become more dominant, and develop aggressivity following ovariectomy (9, 42, 46).
It's also interesting to know that gonadectomy lowers metabolism. It's precisely the reason why some gonadectomized animals tend to obesity (3). In fact gonadectomy triples the risk of obesity. An interesting fact is that a study showed that wandering cats, just like sedentary cats, are at risk of putting on weight following gonadectomy. The study was done on 14 cats, which physical condition was evaluated at the time the gonadectomy was done, and one year after. They put on weight significantly (37).
A study shows that gonadectomized dogs have twice the risk of sexually intact dogs of developping an osteosarcoma (20). Other researchers showed that in rottweilers, the risk in dogs (both males and females) who were gonadectomized before the age of one year old is higher compared to the risk in sexually intact ones. The risk of dogs gonadectomized before the age of one year old is 1 out of 4 (23). It is also discouraged to have Irish Wolfhounds castrated, because it highers the risk of developping osteosarcoma in this breed (59).
A study done in 2001 shows that sexually intact male dogs are significatively less encline to progress from a mild alteration of cognitive fonctions toward a severe one than castrated ones. The study included 4 behaviors. Results suggest that testosterone presence in blood in sexually intact aging male dogs could slow down the progression of the alteration of cognitive fonctions in dogs showing signs of mild alteration (30).
Oestrogen (hormone secreted by ovaries) should play a similar protective role in sexually intact bitches, unfortunately there were not enough available intact bitches for this study, in order to verify this hypothesis (30).
The Veterinary Medical Data Program (VMDP) data, including 1019 canin diabetes cases from 14 veterinary medicine schools, showed a significatively increased risk of developping diabetes mellitus in sexually intact and gonadectomized bitches, compared to the risk of sexually intact males, and a significatively increased risk in castrated males (55).
A study done in 2005 on a cohort of 1733 Boxers, from 325 litters, studied from birth to the age of 10 years old shows that the risk of mortality in gonadectomized dogs, males and females, is higher than the risk of sexually intact dogs (51).
According to a study done in 1994, in dogs younger than 4 years old, sexually intact bitches are at lower risk of developping a chronic superficial keratosis than castrated and intact male dogs, and gonadectomized bitches (31).
Gonadectomized male and female dogs have a higher risk than intact male dogs to develop an acute pancreatitis (32). And they also have a higher risk than sexually intact females (33).
According to a study, the risk of developping a fatal acute pancreatitis would be higher in dogs who are overweighed, and in hypothyroidic ones (33). Two conditions that can be related to gonadectomy.
Statistics done between 1982 and 1995, on 1383 dogs suffering from a cardiac tumor, show that the risk of developping a cardiac tumor in gonadectomized bitches is 4 times higher than the risk of sexually intact bitches. Moreover, their risk of developping an hemangiosarcoma (cancer) is 5 times higher than the risk of sexually intact bitches. Castrated dogs risk is slightly higher than the risk of intact males, who have a 2.4 higher risk than sexually intact bitches. So this study suggests that gonadectomy increases the risks of developping a cardiac tumor in dog males and females. Sexually intact females having the lowest risk, and ovariectomized females beign at the higher risk (22).
There are some unusual hyperadrenocorticism (Cushing disease) clinical manifestations in castrated male dogs, including prostatomegaly and perianal adenoma (21).
Osteoporosis in women is caused by a lack of oestrogens following menopause (ovaries having ceased to produce that hormone). Furthermore, even if the female rat is the ideal model to sudy this phenomena and discover treatments for women, gonadectomized bitches have also been used in laboratories (39). Ovariectmized bitches have a bone production alterated following ovariectomy. Studies done on male beagles also demostrated a reduced bone mass (production of bone being less important compaired to its resorption) in castrated dogs (45).
A study done on 1 226 159 vaccinated in 360 veterinary hospitals shows that gonadectomized adult small dogs have a risk 27% to 38% higher than the risk in small dogs, intacts, of developping an allergy following vaccination (the risk decreasing inversly proportional to the weight) (41).
Also, a study done on 496 189 vaccinated cats, in 329 veterinary hospitals, in the goal to determine the incidence of vaccine associated adverse reactions within 30 days of vaccination, and classifed as nonspecific vaccine reaction, allegic reaction, urticaria, shock or anaphylaxis, showed that the risk of developping those reactions was higher in gonadectomized cats than in sexual intacts ones. The most frequently observed reactions being lethargy with or without fever (58).
An other study done in 2004, Spain et al. showed that dogs, both males and females, gonadectomized at a young age, are at higher risk of developping hip dysplasia, noise phobia and to exhibe more sexual behaviors than those who were gonadectomized later in life (47).
In cats, skin soft tissu angiosarcoma is more commun in old castrated males. This cancer can be difficult to treat since metastases, especialy in lungs and liver, are common (21).
Old castrated siamese male cats have a predisposition to lipomas (which are benign fatty tumors) (21).
A study has been done in the goal to determine which risk factors of developping certain diseases of the urinary system in cats. Results showed that castrated males have an increased risk of developping certain urinary diseased, except bacterial urinary infections and uriary incontinence, and that ovariectomized females have an increased risk of developping urocystolithiasis, bacterial urinary infections and neoplasia. The study shows that intact females have a lower risk of developping uriary diseases, except neurogenic didorders and iatrogenic wounds (34).
Gonadectomized cats have a higher risk than intact cats of developping calcium oxalate and magnesium ammonium phosphate urolithiasis (56).
A study showed that gonadectomized cats (males and females), have a higher risk than sexually intact cats, of developing the feline urological syndrome (38).
In ferrets, the hypothethical cause of hyperadrenocorticism, a very frequent disease in ferrets, affecting most females (75% of affected ferrets are females), is gonadectomy at a too early age.
MYTHS AND INCOMPLETE INFORMATION AOUT GONADECTOMY
An intact dog won't necessarily be frustrated if he doesn't get the opportunity to breed. In a dog pack, adolescents are not allowed to mate, and domination of dogs higher in the hierarchy has the effect of decreasing their sex drive. It's a "phsychological castration". This phenomena is called "adolescents marginalisation" (10,11).
Dogs who have developped aggessivity won't necessarily be "cured" by gonadectomy. Some veterinarians recommenda chemical sterilisation, which is temprary, so they can see the effects of an eventual gonadectomy, before they proceed to the irreversible surgery. A sudy shows that aggressive behaviors towards their family humans can be decreased significatively by castration in 1/3 of dogs who present this behavior. Age at which the castration was performed and the lenght of the period of time the behavior was exhibited are not related to the level of success of castration in the modification of the aggressive behavior (48).
Intact males who are well socialized and obediance trained at a young age won't develop behavioral problems such as urinary marquing or territory aggression (behavior mostly related to males). The fact that the owner does obediance training with hi/her dog in the house, increases his/hr leadership on the dog, which results in a decrease of the risks that a male starts marquing his territory in the house, since the owner makes it clear to the dog that his human is the pack leader, and the dog is less incline to try to dominate (12).
ALTERNATIVE SURGICAL TECHNIQUES
In the goal to prevent indesirable litters, and also to prevent useless suffering, without altering the sexual hormones physiology, vasectomy and tubular liguature are two interesting alternatives. Uterine ablation, without touching the ovaries, eliminates pyometra risks.
On the other hand, you should know that those techniques won't modify the animal sexual behavior.
REFERENCES:
(1) Hadley, M. E., Endocrinology, 1988, Second Edition, Prentice Hall Englewood, 549 pages
(2) Alberts, B., D. Bray, J. Lewis, M. Raff, K. Roberts and J. D. Watson, Molecular Biology of the Cell, 1983, Garland
Publishing, Inc., New York, 1148 pages
(4) Gregory S.P., "Developments in the understanding of the pathophysiology of urethral sphincter mechanism in competence
in the bitch", Br. Vet. J., 1994 Mar;150(2):135-150
(5) Holt P. E. and M. V. Thrusfield, "Association in bitches between breed, size, neutering and docking, and acquired urinary
incontinence due to incompetence of the urethral sphincter mechanism", Vet. Rec., 1993 Aug 21;133(8):177-180)
(6) Arnold S., "Urinary incontinence in castrated bitches. Part 1: Significance, clinical aspects and etiopathogenesis", Schweiz
Arch Tierheilkd, 1997;139(6):271-276)
(7) Aaron, A., K. Eggleton, C. Power, P. E. Holt, "Urethral sphincter mechanism incompetence in male dogs: a retrospective
analysis of 54 cases", Vet. Rec. 1996 Nov 30;139(22):542-546)
(8) Panciera DL., "Hypothyroidism in dogs: 66 cases (1987-1992)", J. Am. Vet. Med. Assoc., 1994, Mar
1;204(5):761-767)
(9) Fogle, B., The Dog's Mind, 1992, Howell Book House, New York, 201 pages and Tucker, M., Solving your dog
Problems, 1988, Howell Book House Inc., New York, 146 pages)
(10) Dehasse, J., Le Caniche, 1995, Le Jour Editeur, Montr�al, 160 pages
(11) Dehasse, J., Le Doberman, 1995, Le Jour Editeur, Montr�al, 156 pages)
(12) Carlson, J. and R. Green, Good Dogs, Bad Habits, 1995, Firside Books, Toronto, 252 pages)
(13) Mulholland SG, SM. Qureshi, RW. Fritz, H. Silverman, Effect of hormonal deprivation on the bladder defense
mechanism, J Urol 1982 May;127(5):1010-3
(14) Augsburger, H. R., Cruz-Orive, L. M., "Influence of ovariectomy on the canine striated external urethral sphincter (M.
urethralis): a stereological analysis of slow and fast twitch fibres", Urol. Res., 1998, 26(6):417-22
(15) Augsburger, H. R., Cruz-Orive, L. M., "Stereological analysis of the urethra in sexually intact and spayed female dogs",
Acta. Anat. (Basel), 1995, 154(2):135-42
(16) Johnston S.D., Kamolpatana K., Root-Kustritz MV., Johnston G. R., "Prostatic disorders in the dog", Anim. Reprod.
Sci., 2000, Jul., 2; 60-61: 405-15
(17) Bell F.W., Klauser J.S., Hayden D.W., Feeney D.A., Johnston S.D., "Clinical and pathologic features of prostatic
adenocarcinoma in sexually intact and castrated dogs: 31 cases (1970-1987), J. Amer. Vet. Med. Assoc., 1991 Dec.1;
199(11): 1623-30
(18) Krawiec D.R., Heflin D., "Study of prostatic disease in dogs: 177 cases (1981-1986)", J. Am. Vet. Med. Assoc.,
1992, Apr. 15; 200(8): 1119-22
(19) Whitehair J.G., Vasseur P.B., Willits N.H., �Epidemiology of cranial cruciate ligament rupture in dogs�, J. Am. Vet. Med. Assoc., 1993, Oct. 1; 203(7): 1016-9
(22) Ware WA, Hopper DL., �Cardiac tumors in dogs: 1982-1995�, J. Vet. Intern. Med., 1999, Mar-Apr;13(2):95-103.
(23) Cooley DM, Beranek BC, Schlittler DL, Glickman NW, Glickman LT, Waters DJ., �Endogenous gonadal hormone exposure and bone sarcoma risk�, Cancer Epidemiol Biomarkers Prev. 2002, Nov;11(11):1434-40.
(24) Duval JM, Budsberg SC, Flo GL, Sammarco JL., �Breed, sex, and body weight as risk factors for rupture of the cranial cruciate ligament in young dogs�, J Am Vet Med Assoc. 1999, Sep 15;215(6):811-4.
(25) Milne KL, Hayes HM Jr., "Epidemiologic features of canine hypothyroidism", Cornell Vet., 1981, Jan;71(1):3-14.
(26) Teske E, Naan EC, Van Dijk EM, Van Garderen E, Schalken JA., "Canine prostate carcinoma: epidemiological evidence of an increased risk in castrated dogs", Mol. Cell. Endocrinol., 2002, Nov 29;197(1-2):251-255.
(27) Obradovich J., Walshaw R., Goudlaud E., "The influence of castration on the development of prostatic carcinoma in the dog. 43 cases (1978 - 1985)", J. Vet. Intern Med., 1987, Oct - Dec; 1(4):183-7.
(28) Slauterbeck J.R., Pankratz K., Xu K.T., Bozeman S.C., Hardy D.M., "Canine ovariohysterectomy and orchidectomy increases the prevalence of ACL injury", Clin. Orthop.-Relat. Res. 2004, Dec; (429):301-5
(29) Spain C.V., Scarlett J.M., Houpt K.A., "Long-term risks and benefits of erarly-age gonadectomy in cats", J. Am. Vet. Med. Assoc., 2004, Feb 1;224:372-9(3)
(30) Hart B.L., "Effect of gonadectomy on subsequent development of age-related cognitive impairment in dogs", J. Am. Vet. Assoc., 2001 Jul 1;219(1):51-56
(31) Chavkin M.J., Roberts S.M., Salman M.D., Severin G.A., Scholten N.J., "Risk factors for development of chronic superficial keratitis in dogs", J. Am. Vet. Assoc., 1994, May 15;204(10):1630-4
(33) Hess R.S., Kass P.H., Shofer F.S., Van Winkle T.J., Washabau R.J., :Evaluation of risk factors for fatal acute pancreatitis in dogs:, J. Am. Vet. Assoc., 1999, Jan 1;214(1):46-51
(34) Lekcharoensuk C., Osborne C.A., Lulich J.P., "Epidemiologic study of risk factors for lower urinary tract diseases in cats", J. Am. Vet. Assoc., 2001, May 1;218(9):1429-35
(35) Stocklin-Gautschi N.M., Hassig M., Reichler I.M., Hubler M., Arnold S., "The relationship of urinary incontinence to early spaying in bitches", J. Reprod. Fertil. Suppl., 2001;57:233-6
(36) Lekcharoensuk C., Lulich J. P., Osborne C. A., Pusoonthornthum R., Allen T. A., Koehler L. A., Urlich L. K., Carpenter K. A., Swanson L. L., "Patient and environmental factors associated with calcium oxalate urolithiasis in dogs", J. Am. Vet. Med. Assoc., 2000, Aug 15;217(4):515-9
(37) Scott K.C., Levy J.K., Gorman S.P., Newell S.M., "Body condition of feral cats and the effect of neutering", J. Appl. Anim. Welf. Sci., 2002;5(3):203-13
(38) Willeberg P., Priester W. A., "Feline urological syndrome: Associations with some time, space and individual patient factors", Am. J. Vet. Res., 1976, Aug;37(8):975-8
(39) Barlet J. P., Coxam V., Davicco M. J., Gaumet N., "Animal models of post-menopausal osteoporosis", Reprod. Nutr. Dev., 1994;34(3):221-36
(40) Overley B., Shofer F. S., Goldschmidt M. H., Sherer D., Sorenmo K. U., "Association between ovarihysterectomy and feline mammary carcinoma", J. Vet. Intern. Med., 2005, Jul-Aug;19(4):560-3.
(41) Moore G. E., Guptill L. F., Ward M. P., Glickman N. W., Faunt K. K., Lewis H. B., Glickman L. T., "Adverse events diagnosed within three days of vaccine administration in dogs", J. Am. Vet. Med. Assoc., 2005, Oct 1;227(7):1102-8.
(42) O' Farrell, V., Peachey, E., "Behavioural effects of ovariohysterectomy on bitches", Journal of Small Animal Practice, 1990, 31(12): 595-598.
(43) Powers M.Y., Martinez S.A., Lincoln J.D., Temple C.J., Arnaiz A., "Prevalence of cranial cruciate ligament rupture in a population of dogs with lameness previously attributed to hip dysplasia: 369 cases (1994-2003)", J. Am. Vet. Med. Assoc., 2005, Oct 1;227(7):1109-11.
(44) Sorenmo K., Goldschmidt M., Shofer F., Goldkamp C., Ferracone J., "Immunohistochemical Characterization of canine prostatic carcinoma and correlation with castration status and castration time", Vet., Comparative Oncology, 2003, 1(1):48-56.
(45) Fukuda S., Iida H., "Effects of orchidectomy on bone metabolism in beagle dogs", J. Vet. Med. Sci., 2000; 62(1):69-73.
(46) Heindenberger E., Unshelm J., "Changes in the behavior of dogs after castration", Tierarztl Prax., 1990, Feb;18(1):69-75.
(47) Spain C.V., Scarlett J.M., Houpt K.A., "Long-term risks and benefits of early-age gonadectomy in dogs", J. Am. Vet. Med. Assoc., 2004, Feb. 1;224(3):380-7.
(48) Neilson J.C., Eckstein R.A., Hart B.L., "Effects of castration on problem behaviors in male dogs with reference to age and duration of behavior", J. Am. Vet. Med. Assoc., 1997, Jul 15;211(2):180-2.
(49) Howe L.M., Slater M.R., Boothe H.W., Hobson H.P., Holcom J.L., Spann A.C., "Long-term outcome of gonadectomy performed at an early age or traditional age in dogs", J. Am. Vet. Med. Assoc., 2001, Jan 15;218(2):217-21.
(50) Salameri K.R., Bloomberg M.S., Scruggs S.L., Shille V., "Gonadectomy in immature dogs: effects on skeletal, physical, and behavioral development", J. Am. Vet. Med. Assoc., 1991, Apr 1;198(7):1193-203.
(51) van Hagen M.A., Ducro B.J., van den Broek J., Knol B.W., "Life expectancy in a birth cohort of Boxers followed up from weaning to 10 years of age", Am. J. Vet. Res., 2005, Sep;66(9):1646-50.
(52) Arnold S., Arnold P., Hubler M., Casal M., Rusch P., "Urinary incontinence in spayed female dogs: frequency and breed disposition", Schweiz Arch Tierheilkd, 1989;131(5):259-63.
(53) Blendinger C., Blendinger K., Bostedt H., "Urinary incontinence in spayed bitches. 1. Pathogenesis, incidence and disposition", Tierarztl Prax, 1995, Jun;23(3):291-9.
(54) Sorenmo K.U., Goldschmidt M.H., Shofer F.S., Goldkamp C., Ferracone J., "Evaluation of cyclooxygenase-1 and cyclooxygenase-2 expression and the effect of cyclooxygenase inhibitors in canine prostatic carcinoma", Vet. and Comparative Oncology, March 2004, Vol. 2, Issue 1, p13.�
(55) Marmor M., Willeberg P., Glickman L.T., Priester W.A., Cypess R.H., Hurvitz A.I., "Epizootiologic patterns of diabetes mellitus in dogs", Am. J. Vet. Res., 1982, Mar;43(3):465-70.
(56) Lekcharoensuk C., Lulich J.P., Osborne C.A., Koehler L.A., Urlich L.K., Carpenter K.A., Swanson L.L., "Association between patient-related factors and risk of calcium oxalate and magnesium ammonium phosphate urolithiasis in cats", J. Am. Vet. Med. Assoc., 2000, Aug 15;217(4):520-5.
(57) Bryan, J.N., Keeler M.R., Henry C.J., Bryan M.E., Hahn A.W., Caldwell C.W., "A population study of neutering status as a risk factor for canine prostate", Prostate, 2007, Aug 1;67(11):1174-81.
Sexual hormones are anabolic steroids. The play a role in many organs growth. They increase muscular proteins synthesis. They play an important role in long bones growth (legs...), and later, they inhibit those bones linear growth (1,50). Meaning that dependently of the age at which a dog is sterilized, his/her legs will be either shorther or longer than that they would have been without external intervention. Which doesn't necessarily mean a marked difference, but can cause orthopdic problems, like we'll see later.
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