Many clients ask us when they should spay/neuter their puppy. We encourage our clients to wait until their puppy is older. Below are two articles which explain why later is better than sooner !


Early Spay-Neuter Considerations for the Canine Athlete - One Veterinarian's Opinion

by Chris Zink DVM, PhD, DACVP

Those of us with responsibility for the health of canine athletes need to continually read and evaluate new scientific studies to ensure that we are taking the most appropriate care of our performance dogs. This article provides evidence through a number of recent studies to suggest that veterinarians and owners working with canine athletes should revisit the standard protocol in which all dogs that are not intended for breeding are spayed and neutered at or before 6 months of age.

Orthopedic Considerations
A study by Salmeri et al in 1991 found that bitches spayed at 7 weeks grew significantly taller than those spayed at 7 months, who were taller than those not spayed (or presumably spayed after the growth plates had closed).(1) A study of 1444 Golden Retrievers performed in 1998 and 1999 also found bitches and dogs spayed and neutered at less than a year of age were significantly taller than those spayed or neutered at more than a year of age.(2) The sex hormones, by communicating with a number of other growth-related hormones, promote the closure of the growth plates at puberty (3), so the bones of dogs or bitches neutered or spayed before puberty continue to grow. Dogs that have been spayed or neutered well before puberty can frequently be identified by their longer limbs, lighter bone structure, narrow chests and narrow skulls. This abnormal growth frequently results in significant alterations in body proportions and particularly the lengths (and therefore weights) of certain bones relative to others. For example, if the femur has achieved its genetically determined normal length at 8 months when a dog gets spayed or neutered, but the tibia, which normally stops growing at 12 to 14 months of age continues to grow, then an abnormal angle may develop at the stifle. In addition, with the extra growth, the lower leg below the stifle likely becomes heavier (because it is longer), and may cause increased stresses on the cranial cruciate ligament. In addition, sex hormones are critical for achieving peak bone density.(4) These structural and physiological alterations may be the reason why at least one recent study showed that spayed and neutered dogs had a higher incidence of CCL rupture.(5) Another recent study showed that dogs spayed or neutered before 5 1/2 months had a significantly higher incidence of hip dysplasia than those spayed or neutered after 5 1/2 months of age, although it should be noted that in this study there were no standard criteria for the diagnosis of hip dysplasia.(6) Nonetheless, breeders of purebred dogs should be cognizant of these studies and should consider whether or not pups they bred were spayed or neutered when considering breeding decisions.

Cancer Considerations
A retrospective study of cardiac tumors in dogs showed that there was a 5 times greater risk of hemangiosarcoma, one of the three most common cancers in dogs, in spayed bitches than intact bitches and a 2.4 times greater risk of hemangiosarcoma in neutered dogs as compared to intact males.(7) A study of 3218 dogs demonstrated that dogs that were neutered before a year of age had a significantly increased chance of developing bone cancer.(8) A separate study showed that neutered dogs had a two-fold higher risk of developing bone cancer.(9) Despite the common belief that neutering dogs helps prevent prostate cancer, at least one study suggests that neutering provides no benefit.(10) There certainly is evidence of a slightly increased risk of mammary cancer in female dogs after one heat cycle, and for increased risk with each subsequent heat. While about 30 % of mammary cancers are malignant, as in humans, when caught and surgically removed early the prognosis is very good.(12) Luckily, canine athletes are handled frequently and generally receive prompt veterinary care.

Behavioral Considerations
The study that identified a higher incidence of cranial cruciate ligament rupture in spayed or neutered dogs also identified an increased incidence of sexual behaviors in males and females that were neutered early.(5) Further, the study that identified a higher incidence of hip dysplasia in dogs neutered or spayed before 5 1/2 months also showed that early age gonadectomy was associated with an increased incidence of noise phobias and undesirable sexual behaviors.(6) A recent report of the American Kennel Club Canine Health Foundation reported significantly more behavioral problems in spayed and neutered bitches and dogs. The most commonly observed behavioral problem in spayed females was fearful behavior and the most common problem in males was aggression.(12)

Other Health Considerations
A number of studies have shown that there is an increase in the incidence of female urinary incontinence in dogs spayed early (13), although this finding has not been universal. Certainly there is evidence that ovarian hormones are critical for maintenance of genital tissue structure and contractility.(14, 15) Neutering also has been associated with an increased likelihood of urethral sphincter incontinence in males.(16) This problem is an inconvenience, and not usually life-threatening, but nonetheless one that requires the dog to be medicated for life. A health survey of several thousand Golden Retrievers showed that spayed or neutered dogs were more likely to develop hypothyroidism.(2) This study is consistent with the results of another study in which neutering and spaying was determined to be the most significant gender-associated risk factor for development of hypothyroidism.(17) Infectious diseases were more common in dogs that were spayed or neutered at 24 weeks or less as opposed to those undergoing gonadectomy at more than 24 weeks.(18) Finally, the AKC-CHF report demonstrated a higher incidence of adverse reactions to vaccines in neutered dogs as compared to intact.(12)

I have gathered these studies to show that our practice of routinely spaying or neutering every dog at or before the age of 6 months is not a black-and-white issue. Clearly more studies need to be done to evaluate the effects of prepubertal spaying and neutering, particularly in canine athletes.

Currently, I have significant concerns with spaying or neutering canine athletes before puberty. But of course, there is the pet overpopulation problem. How can we prevent the production of unwanted dogs while still leaving the gonads to produce the hormones that are so important to canine growth and development? One answer would be to perform vasectomies in males and tubal ligation in females, to be followed after maturity by ovariohysterectomy in females to prevent mammary cancer and pyometra. One possible disadvantage is that vasectomy does not prevent some unwanted behaviors associated with males such as marking and humping. On the other hand, females and neutered males frequently participate in these behaviors too. Really, training is the best solution for these issues. Another possible disadvantage is finding a veterinarian who is experienced in performing these procedures. Nonetheless, some do, and if the procedures were in greater demand, more veterinarians would learn them.

I believe it is important that we assess each situation individually. For canine athletes, I currently recommend that dogs and bitches be spayed or neutered after 14 months of age.

References:
1.Salmeri KR, Bloomberg MS, Scruggs SL, Shille V.. Gonadectomy in immature dogs: effects on skeletal, physical, and behavioral development. JAVMA 1991;198:1193-1203
2.http://www.grca.org/healthsurvey.pdf
3.Grumbach MM. Estrogen, bone, growth and sex: a sea change in conventional wisdom. J Pediatr Endocrinol Metab. 2000;13 Suppl 6:1439-55.
4.Gilsanz V, Roe TF, Gibbens DT, Schulz EE, Carlson ME, Gonzalez O, Boechat MI. Effect of sex steroids on peak bone density of growing rabbits. Am J Physiol. 1988 Oct;255(4 Pt 1):E416-21.
5.Slauterbeck JR, Pankratz K, Xu KT, Bozeman SC, Hardy DM. Canine ovariohysterectomy and orchiectomy increases the prevalence of ACL injury. Clin Orthop Relat Res. 2004 Dec;(429):301-5.
6.Spain CV, Scarlett JM, Houpt KA. Long-term risks and benefits of early-age gonadectomy in dogs. JAVMA 2004;224:380-387.
7.Ware WA, Hopper DL. Cardiac tumors in dogs: 1982-1995. J Vet Intern Med 1999 Mar-Apr;13(2):95-103
8.Cooley DM, Beranek BC, Schlittler DL, Glickman NW, Glickman LT, Waters D, Cancer Epidemiol Biomarkers Prev. 2002 Nov;11(11):1434-40
9.Ru G, Terracini B, Glickman LT. Host related risk factors for canine osteosarcoma. Vet J. 1998 Jul;156(1):31-9.
10.Obradovich J, Walshaw R, Goullaud 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
11.http://www.akcchf.org/pdfs/whitepapers/Biennial_National_Parent_Club_Canine_Health_Conference.pdf
12.Meuten DJ. Tumors in Domestic Animals. 4th Edn. Iowa State Press, Blackwell Publishing Company, Ames, Iowa, p. 575
13.Stocklin-Gautschi NM, Hassig M, Reichler IM, Hubler M, Arnold S. The relationship of urinary incontinence to early spaying in bitches. J. Reprod. Fertil. Suppl. 57:233-6, 2001
14.Pessina MA, Hoyt RF Jr, Goldstein I, Traish AM. Differential effects of estradiol, progesterone, and testosterone on vaginal structural integrity. Endocrinology. 2006 Jan;147(1):61-9.
15.Kim NN, Min K, Pessina MA, Munarriz R, Goldstein I, Traish AM. Effects of ovariectomy and steroid hormones on vaginal smooth muscle contractility. Int J Impot Res. 2004 Feb;16(1):43-50.
16.Aaron A, Eggleton K, Power C, Holt PE. Urethral sphincter mechanism incompetence in male dogs: a retrospective analysis of 54 cases. Vet Rec. 139:542-6, 1996
17.Panciera DL. Hypothyroidism in dogs: 66 cases (1987-1992). J. Am. Vet. Med. Assoc., 204:761-7 1994
18.Howe LM, Slater MR, Boothe HW, Hobson HP, Holcom JL, Spann AC. 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.



Deciding Whether and When to Neuter a Golden Retriever

By Rhonda Hovan, From The Golden Retriever News Vol. LXVI No. 5

A focus on the serious issues of pet overpopulation and unwanted puppies has led to the common practice of neutering dogs prior to sexual maturity, often near the age of six months. While this clearly helps reduce unplanned breedings and thereby may serve the public interest, research is increasingly showing that it may not be in the best health interests of an individual dog with a responsible owner. Breeds of dogs vary considerably with regard to their rate of maturity and risk for specific diseases, and the interaction of these factors with natural hormones should properly be taken into consideration when deciding whether and when to neuter a dog. However, appropriately tailoring neutering recommendations to a breed requires awareness of the ways in which neutering and the age of neutering affect specific breeds, and it may be impossible for veterinarians to know this in detail for every breed. Therefore, below is a review of health consequences to consider when deciding whether and/or when to neuter a Golden Retriever. The term "Goldens" will be used when the data are specific to Goldens, and most of this data come from a large breed health survey scientifically conducted and analyzed by a veterinary epidemiologist. The term "dogs" will be used when the data are applicable to many breeds, and supporting references are provided. In some cases the findings have been substantiated across many breeds, but relative risk is also defined specifically for Goldens. The term "neuter" refers to either sex. Please note that there are both health benefits and detriments associated with neutering and various neutering ages, so decisions will need to balance these complex factors. It is relevant to consider what diseases are more and less common in the breed, and also what diseases have greater or lesser consequences to the dog, so that information is also provided. For example, it is important with reference to cancer risk to know that 18% of all Goldens die from hemangiosarcoma but that testicular cancer is rare (less than ½ of 1%), so that appropriate weight can be given to the effect that neutering has on each of those cancers. Health Consequences Associated with Neutering and the Age of Neutering - Neutered dogs have a higher incidence of hypothyroidism than do intact dogs. Male Goldens neutered prior to one year of age have an 80% increased risk of hypothyroidism and female Goldens neutered prior to one year of age have a 60% increased risk of hypothyroidism, as compared to those neutered after one year of age or not neutered. Hypothyroidism is a common but treatable disease in the breed.

- Neutered dogs have a greater incidence of hip dysplasia and torn cruciate ligaments than intact dogs, and there is some evidence to suggest that this risk is most pronounced in dogs neutered prior to sexual maturity. Hip dysplasia is common in Goldens, and torn cruciate ligaments are less common but not rare. Both of these diseases can be treated surgically, but treatment is costly and success is variable depending on many factors.

-There is some evidence that the incidence of cardiac hemangiosarcoma is greatly increased (2-5 times) in neutered dogs, and that the risk of splenic hemangiosarcoma may also be increased in neutered dogs. Hemangiosarcoma is the most common cancer in the breed, causing the death of approximately 1 in 5 Goldens. Most of these tumors occur in the spleen, with fewer but still a substantial number in the heart. This is a rapidly progressing and incurable cancer.

-Several studies indicate that the incidence of osteosarcoma (bone cancer) is significantly higher in neutered dogs than in intact dogs, but there is some evidence that this increase is not as great when neutering occurs after sexual maturity. This cancer affects about 5% of Goldens, and is not curable. -Dogs neutered prior to sexual maturity grow taller than their natural genetic potential, and their bone structure is altered toward a more narrow, lanky appearance. Taller Goldens have shorter life spans than shorter Goldens. Among male Goldens, the shortest males live 2.2 years longer than the tallest males; and among female Goldens, the shortest females live 1.1 years longer than the tallest females. It is unlikely that neutering a Golden prior to sexual maturity will alter the dog’s potential height from extremely short to extremely tall, but it will make a noticeable difference in height and thus potentially in life span.

- Neutered females have a greatly increased risk of urinary incontinence as compared to those not neutered, but there is some evidence that this increased risk is less significant for dogs neutered after sexual maturity. Urinary incontinence is neither common nor rare in Goldens, and can often (but not always) be treated successfully. - Females neutered prior to their first heat cycle have less than ½ of 1% chance of developing mammary cancer (breast cancer). In females neutered after the first cycle but before the second, this risk increases to 4%. And if a female is not neutered until after her second heat cycle, this risk increases to about 13%. If detected early through regular mammary exams, most but not all mammary cancers can be treated successfully with surgery and sometimes additional therapies.

- Males with one or more testicles located in the abdomen (cryptorchidism) are at high risk for testicular cancer and should be neutered prior to 15 months of age, which eliminates this risk. It is not necessary to neuter these dogs prior to sexually maturity to avoid testicular cancer. Testicular cancer is rare (less than ½ of 1%) in dogs with both testicles normally descended into the scrotum.

- Females that remain intact are exposed to a significant risk for pyometra (a life threatening uterine infection) that rises with every heat cycle, particularly after the age of five years. Pyometra is a common and rapidly progressing disease in Goldens that must be diagnosed promptly to be successfully treated. - Males that remain intact frequently develop an enlarged prostate gland (benign prostatic hyperplasia) as they age, particularly over the age of seven years. This is not a serious disease, and while it can sometimes be managed medically, neutering affected dogs is curative. This is not to be confused with prostate cancer which is uncommon in the breed, although more common in neutered males than intact males.

Taking all of the above factors into consideration, there is good evidence to support that it is in the best overall health interests of the dog to neuter female Goldens after sexual maturity, at approximately one year of age. This typically allows a female to have one heat cycle but not two, which keeps the risk of mammary cancer low while still providing her with some important health benefits gained by maturing with natural hormones. Of course, the female must be kept on leash or securely fenced away from males for the full three weeks of her heat cycle to avoid unwanted pregnancy, so this should not be undertaken unless the owner is able to be certain that there is no possibility of an accidental breeding.

There are no clear significant health benefits to neutering a normal male, so this decision should be based on factors other than the health of the dog, such as preventing unwanted breedings, reducing the risk of male-to-male dominance/aggression, and reducing roaming behavior and urine marking. If a male is going to be neutered, there is good evidence to support that it is in the overall best health interests of the dog to neuter male Goldens after sexual maturity, at approximately one year of age. Neutering a male after two years of age has less impact on behavior, so if behavioral considerations are important to the owner, neutering should be done prior to the age of two.