In Practice: first published as 10.1136/inp.l5007 on 5 September 2019. Downloaded from http://inpractice.bmj.com/ on September 22, 2019 at James Cook University.

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CLINICAL PRACTICE
David Yates
qualified from
the University
Prepubertal neutering in cats
and dogs
of Liverpool
in 1991. He
worked for the
RSPCA for over 25 years, and
was the hospital director
of the RSPCA Greater
Background: Neutering cats and dogs is the most common elective procedure undertaken in small animal
Manchester Animal Hospital. practice. Neutering is often at the request of an owner but may be carried out on unowned animals as a policy
He also taught students on decision in a charity practice, or as a life-saving intervention in cases such as testicular torsion or pyometra.
clinical placements from Considerations influencing the decision to neuter include owner, animal and veterinary factors.
both Nottingham and Bristol
universities. He now works
in private practice in Ludlow. Aim of the article: Here, we consider the timing of the procedure, the risks and benefits and technicalities of
performing prepubertal gonadectomy in the dog and cat. Traditionally, cats and dogs are neutered from six
Rosa months old; in contrast, prepubertal neutering is defined as ovariectomy/ovariohysterectomy or castration
Leedham at six to 16 weeks of age in both species. It should be noted that large dog breeds may not reach puberty for
qualified many months after this period.
from the
University of
Nottingham in
2016 and has worked for
the RSPCA at the Greater
Manchester Animal Hospital
since graduation. She Why should we neuter? behavioural and health outcomes will ultimately
has been involved in the In an ideal world, all companion animals would guide an owner’s decision regarding neutering their
development of veterinary be under the care of a responsible owner who has pet. A recent paper by Downes and others (2015)
clinics – particularly internal
the capacity to engage in an informed discussion investigated the factors and perceptions which
medicine services – at a
number of RSPCA rehoming with their veterinarian about the health and influence this decision making, such as cultural
centres. wellbeing of their pet. In reality, pet breeding factors, economic status, gender and perceptions
is often uncontrolled and, as a consequence, about their animal (Table 1).
animal charities in the UK are continually faced A breeder may employ neutering as a means to
with many thousands of unwanted pets which prevent overuse of strains within a breed, preserve
have been all too easily acquired and discarded. their ‘product’ and prevent irresponsible breeding.
Surgical gonadectomy is a commonly employed and
effective tool to combat this animal overpopulation Benefits of neutering
and offers charities a financially viable method To the individual animal
to improve the welfare of a large population of It is difficult to evaluate the relative risks and
animals. benefits associated with the neuter status of an
animal, because there is an abundance of influential
Owner/breeder perceptions of neutering factors to consider (ie, breed, age at neutering,
Owner perceptions of neutering, and whether they sex) and this greatly confounds lifetime studies.
doi:10.1136/inp.l5007 believe that the procedure will impart desirable Neutered animals generally have a longer life span
than entire dogs and cats. This may be partially
attributable to the rationale that these animals
are more likely to be responsibly owned and have
KEY LEARNING OUTCOMES engaged with a veterinary professional on at least
one occasion. However, multiple health benefits
After reading this article, you should understand: have been described, which are discussed below.

▢▢ Gonadectomy is the most common elective procedure in small Cats

animals; Males
▢▢ Societal and individual patient risk/benefits are derived from In cats, reproductive behaviours (eg, urine spraying
and sexual aggression) are reduced (or eliminated)
gonadectomy;
by neutering. Neutered males may be less likely
▢▢ The timing of gonadectomy alters the relative risks/benefits; to exhibit risk behaviours such as roaming and
▢▢ Prepubertal gonadectomy is the optimal surgical method of fighting, thus reducing the risk of involvement in
population control in cats; road traffic collisions (RTCs) and other accidents,
▢▢ Prepubertal gonadectomy may offer significant advantages to the although the ‘Bristol Cats’ cohort study did not
patient in terms of reduced recovery and surgical times. identify neuter status as a risk factor for RTCs
(Wilson and others 2017). Neutering decreases the

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Table 1: Owner perceptions influencing the decision to neuter* The incidence of mammary neoplasia in dogs
Enabling perceptions Disabling perceptions from reported veterinary cases is 3.4 per cent,
Control of unwanted behaviour Financial cost of procedure with approximately half of these cases being
benign fibroadenomatous and half malignant
Positive health outcomes (ie, prevention of Concerns regarding negative health and
adenocarcinomas (Dorn and others 1968).
neoplasia) welfare outcomes (ie, infliction of pain,
weight gain) Mammary tumours are significantly less likely in
bitches neutered before puberty. If spayed before
Owner responsibility (unless pet is being Perception that existing controls are
used for breeding) adequate the first oestrous cycle, a 0.5 per cent lifetime risk
has been reported, which increases to 8 per cent
Control of breeding within a household Concerns about change in personality and
and 26 per cent when spaying between the first and
effects on sexuality/masculinity of the
animals (particularly apparent with male second cycle and after the second cycle, respectively
owners) (Schneider and others 1969).
Veterinary advice Belief that it is not necessary to neuter if Bleeding during oestrous can be inconvenient
indoor pet and behavioural problems associated with entire
Desire to breed an animal females (ie, aggression or nesting behaviour
during pseudopregnancy) can be challenging for
*As described by Downs and others (2015)
owners. Table 3 describes other conditions that are
prevented or reduced by spaying.
risk of feline immunodeficiency virus (FIV) which is
commonly transmitted by fighting and bite wounds. To a population of animals
Other conditions reduced or prevented by neutering In the UK, most cat breeding is unplanned and
are described in Table 2. uncontrolled and owners are often unaware of the
breeding cycles in their pets. Entire female cats with
Females outdoor access have a high chance of conception,
Entire female cats have a seven times greater risk particularly in the summer months.
of developing mammary tumours than spayed cats, In contrast, misalliance in the dog should
with cats that are spayed when they are less than six be more amenable to control. The behavioural
months old showing a 91 per cent reduction in risk and physiological changes may be apparent in
of mammary carcinoma compared with unneutered the female and there should not be an outdoor
cats (Overley and others 2005). The majority of reservoir of entire male suitors. Anecdotally, the
mammary tumours are malignant, and most are stray dog problem is now less evident in the UK
carcinomas which infiltrate locally and frequently and relinquished dogs are more likely to be adult
metastasise. animals rather than unwanted litters of puppies.
Often, dogs are signed over to charities because of
Dogs social factors (eg, loss of employment and financial
Males difficulties of the owners).
In intact male dogs, undesirable sexual behaviours The nuisance behaviour of entire male cats (eg,
such as urine marking, roaming and mounting mounting, urine spraying, aggression towards
can be reduced by castration. Benign prostatic people and the deleterious impact of cats on prey
hyperplasia commonly occurs in intact dogs that are animals) precludes their being pleasant household
over five years old and sequelae such as prostatitis, pets. Furthermore, feral cat colonies are often in
abscessation, urinary and defecation issues may suboptimal health, suffering conditions associated
require surgical intervention which is associated with fighting (eg, cat bite abscesses) and infectious
with further morbidity. Castration results in the disease (eg, FIV). Without proactive efforts to limit
reduction of secretory epithelial cells; this decreases future breeding, numbers of such populations will
the size of the prostate which also renders it less inevitably escalate further out of control.
susceptible to infection. Furthermore, testicular
neoplasia is common in intact dogs and is prevented Risks and disadvantages of neutering
by gonadectomy. The short-term risks associated with the neutering
procedure are summarised in Table 4, and relate
Females predominately to surgical and anaesthetic
Pyometra is a hormonally mediated condition complications.
characterised by cystic endometrial hyperplasia and In contrast, long-term risks are likely to be evident
a subsequent secondary bacterial infection. This is some years after the procedure.
a common condition in aged, entire bitches, usually
occurring four to six weeks after oestrous. Although Cats
ovariohysterectomy at the point of diagnosis is Obesity
curative, surgical mortality may be as high as 17 per Gonadectomy has been shown to reduce the
cent when treating pyometra (Johnston and others metabolic rate of cats, thus increasing the risk
2001). of obesity. However, long-term studies have not

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Table 2: Neoplastic and non-neoplastic conditions in male and Table 3: Neoplastic and non-neoplastic conditions in male and
female cats that are reduced or prevented by neutering female dogs that are reduced or prevented by neutering
Males Females Males Females
Lower incidence of abscesses, Reduction in risk of mammary Prevention of testicular neoplasia Prevention of ovarian and uterine
asthma and gingivitis when carcinomas, particularly when the tumours
neutered before 5.5 months of age kitten is spayed when it is younger Reduced risk of benign prostatic Reduction in risk of mammary
(Spain and others 2004) than six months old hyperplasia and sequelae such as neoplasia
Less likely to exhibit risk Prevention of unintended prostatitis and abscessation
behaviour; therefore, lower risk pregnancies or whelping
Prevention of pyometra
of involvement in road traffic complications
collisions Prevention of vaginal prolapse
occurring in young, intact, large
Prevention of testicular neoplasia Prevention of pyometra
breeds during oestrous
Less likely to contract feline Prevention of ovarian and uterine
Prevention of unintended
immunodeficiency virus (FIV)/ neoplasia
pregnancy or whelping
feline leukaemia virus (FeLV)
complications (ie, dystocia)
Less likely to contract FIV/FeLV
Prevention of pseudopregnancy
Prevention of oestrous-related
Prevention of ovarian and uterine
behavioural changes
neoplasia

found a correlation between the age at neutering disease (FLUTD) and consequently there have been
and subsequent susceptibility to obesity (Spain widespread concerns regarding early castration of
and others 2004, Allaway and others 2017). It is not males. However, long-term, retrospective studies
possible to ascertain the exact effect of neutering on have shown a lower risk of FLUTD in cats that were
obesity due to the multitude of factors which may neutered before puberty (Spain and others 2004),
influence an animal’s propensity to become obese with no difference in urethral diameter and function
(ie, diet, exercise and genetics). Therefore, this is an in entire males and those neutered early or at the
important opportunity for a veterinarian to discuss traditional age (Root Kustritz and others 1996).
the importance of provision of an appropriate diet
and adequate opportunities for exercise to ensure Behavioural issues
the maintenance of an appropriate body condition There are widespread concerns that early neutering
(Rowe and others 2017). affects the future behaviour of cats. Studies
have shown that there is no significant effect of
Diabetes mellitus prepubertal neutering on undesirable behaviours
It has been shown that neutered cats are 8.7 times (such as hunting, or fearful or destructive
more likely to develop diabetes mellitus compared behaviour) for at least five years after adoption in
to entire cats (McCann and others 2007). Similarly, shelter kittens (Porters and others 2014).
there is no evidence regarding the influence of
timing of neutering, and genetics, sex and age are Dogs
all contributing factors to this disease. The incidence of multiple neoplastic and non-
neoplastic conditions has been reported to be
Urinary conditions higher in neutered dogs of both sexes than their
It has been postulated that prepubertal neutering in entire counterparts.
males increases the risk of feline lower urinary tract
Neoplastic disease
Table 4: Summary of the short-term risks Some forms of neoplasia are more common in the
associated with neutering procedures and the neutered canine population (Smith 2003) (Fig 1):
expected time of onset of each complication ■■Osteosarcomas (males and females)
■■Haemangiosarcomas (males and females)
Time of onset following Complication
procedure ■■Lymphoma (males and females)
■■Transitional cell carcinomas (males and females)
Hours Pain
Haemorrhage ■■Prostatic tumours (males)

Days Vaginal discharge ■■Mast cell tumours (females)

Lactation
Wound inflammation Further discussion of this extends beyond the
Delayed wound healing scope of this article; there are numerous factors to
Dehiscence
take into account when considering the effect of
Weeks Ovarian remnant neutering on the risk of developing neoplasia. It is
syndrome
important to carefully evaluate the morbidity and

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incidence of perivulvar dermatitis and possibly

chronic vaginitis.
Female dogs Male dogs
Obesity
Osteosarcoma* Neutering is expected to lead to a greater gain
Haemangiosarcoma in body weight than entire dogs, attributable to
increased appetite and metabolic changes. As
Lymphoma*
with cats, client education is imperative to ensure
Transitional cell
that animals maintain a healthy body condition
carcinoma
following neutering.
Mast cell tumour Prostatic neoplasia
Behavioural issues
There is conflicting evidence regarding the effect
of neutering on the temperament of dogs; some
studies have demonstrated that there are a higher
Fig 1: Neoplastic diseases with increased risk in the neutered canine population.
*These diseases have been associated to have an increased risk following number of aggressive and reactive dogs in neutered
prepubertal neutering populations, while others have identified either
no change or a decrease in aggressive behaviour
following gonadectomy. One study has identified
mortality of a particular disease and the prevalence that male dogs castrated at a younger age are more
of this disease within the population, in conjunction likely to demonstrate negative behaviours, the
with the sex, age, breed and environment of the majority of which are related to aggression and
animal. It should also be considered that the fearfulness (McGreevy and others 2018).
higher incidence of certain types of neoplasia may There is often concern regarding the impact of
be partially attributable the longer life span in neutering on the ability of a working dog. However,
neutered animals. studies have shown that time of neutering does
not affect behaviour or placement rate (ie, the
Non-neoplastic conditions successful match of guide dog trainee with owner)
Orthopaedic conditions in a cohort of guide dogs (DeSapio and others 2005),
Neutering is a risk factor for the development and there is no difference in trainability of neutered
of hip dysplasia and cranial cruciate ligament and entire dogs (Serpell and others 2005).
disease (rupture and injury), both of which occur
predominantly in large breed dogs. Delayed closure Current veterinary perception of neutering before
of growth plates has been shown to occur in animals puberty
undergoing prepubertal neutering because closure At present, general veterinary practitioners are often
depends on gonadal hormones (Salmeri and others concerned about both anaesthetic and surgical
1991, Stubbs and others 1996). A hypothesised safety, the potential health implications, and effect
mechanism for the increased incidence of hip on behavioural development when performing early
dysplasia is that this delay affects the hip joint neutering.
conformation. Similarly, deviations of the tibial There are considerable anaesthetic and surgical
plateau angle occur due to changes in closure of the advantages in performing early neutering. When
distal femoral and proximal tibial growth plates, administered appropriate drug combinations,
and this may alter biomechanics by increasing the prepubertal animals usually tolerate anaesthesia very
pressure exerted on the cruciate ligaments (Root well and recover quickly. Surgical times are usually
Kustritz 2014). Elbow dysplasia has been shown to reduced; a lack of abdominal and bursal fat improves
be more common in Labrador retrievers that are visualisation of small blood vessels and facilitates
neutered before six months old compared with effective haemostasis, and smaller incisions are
sexually intact males (Hart and others 2014). usually required. Furthermore, when multimodal
analgesia is used, behavioural scoring systems
Urinary problems suggest that prepubertal patients (including people)
Urinary incontinence (specifically urethral sphincter may be less affected than their adult counterparts
mechanism incontinence) is more common in by both surgery and anaesthesia (Polson and
neutered female dogs compared to entire dogs, others 2014). Studies have demonstrated that early
especially in large breeds. However, the age of neutering has particular advantages; for example, in
neutering bitches that are less than 25 kg has not a postoperative ovariohysterectomy study in bitches,
been shown to impact the incidence of incontinence complications were more common in dogs aged over
(Byron and others 2017). two years (Pollari and others 1996).
Bitches neutered before puberty maintain a
juvenile vulva; this combined with obesity and Animal factors when considering early neutering
urinary incontinence may result in an increased Puppies and kittens booked in for elective

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Table 5: Measures to reduce the risk of hypoglycaemia and hypothermia in prepubertal neutering
patients before, during and after the procedure
Period of care Special measures
Before • Advise clients to give a small meal up to three hours before anaesthesia
admission
Admission • Group house littermates in heated cages
• Schedule as the first surgical cases of the day
Premedication • Avoid a lengthy premedication period
Surgery • Use warmed surgical preparation liquids and minimise wetting of the animal
• Perform only a moderate clip
• Avoid prolonged surgery
• Use heated operating tables
• Ensure the ambient temperature of the operating room is >20oC
Anaesthesia • Fit heat and moisture exchanger devices to non-rebreathing circuits
• Use short-acting and/or ‘reversible’ anaesthetic agents if possible
Recovery • Use warming aids, such as heated recovery kennels, Bair Hugger patient warming device, reflective
foil blankets
• Prompt feeding on recovery (when standing)
• Return to littermates as soon as possible
Discharge • Owners to collect as soon as appropriate

gonadectomy should undergo a complete physical General anaesthetic considerations

examination before admission for surgery to Prepubertal patients and small puppies in particular
ensure that they are healthy and well developed have an increased body surface area to mass
for their age. Additionally, they should be ratio in comparison to their adult counterparts.
vaccinated and treated for internal and external Consequently, they are particularly susceptible
parasites. For example, it would be inappropriate to both hypothermia and hypoglycaemia, unless
to neuter a kitten with anaemia caused by a heavy special measures are implemented before, during
flea burden. and after anaesthesia (Table 5).

Kittens Anaesthetic combinations

To prevent unplanned pregnancies, The Cat Group Dog
(a collection of organisations dedicated to feline Puppies neutered before puberty are likely to be
welfare) recommend neutering at around four of sufficient size to readily permit intravenous
months of age, before a kitten reaches puberty. access. Therefore, vets may not need to alter their
At this time, patients should be healthy and their anaesthetic protocols. However, to reduce the
physical development should closely approximate likelihood of hypothermia in small patients it may
to standard growth curves (Fig 2). Outliers or ‘runts’ be prudent to avoid a lengthy premedication period.
within a litter should be carefully examined before Young patients may have an increased dose
surgery. It is prudent to postpone elective surgery
and allow time to re-evaluate such underdeveloped
3500
kittens.
3000
Puppies
2500 Bottom of female range (g)
Puberty in the dog has a wider age range than in
Mass (g)

Top of male range (g)

the cat. For example, small breeds of dog may start 2000
to ‘cock their leg’ at around four months old and
giant breeds may still be growing (open growth 1500

plates) at 18 months of age. Given the increased 1000

risk of orthopaedic and urinary problems with early
neutering of large dogs in particular, a compromise 500
may be to neuter just before puberty. This will
0
reduce the potential for alterations to growth 0 2 4 6 8 10 12 14 16 18 20
and optimise population control. Regular weight Age (weeks)
checks and discussing behaviour with the owner
at veterinary consultations will indicate a suitable Fig 2: Example of a kitten growth chart used to ensure that prepubertal patients are at an
time for the operation. appropriate weight before they are neutered

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Table 6: Intramuscular anaesthetic combinations suitable for puppies

Combination Drugs Notes
1 Medetomidine 40 μg/kg IM and ketamine 5 mg/kg IM Patients will require additional analgesia (eg,NSAIDs or opiates).
2 Medetomidine 25 μg/kg and butorphanol 0.1 mg/kg IM This is a licensed triple combination but may require additional
Wait 15 minutes analgesia. However, butorphanol is a μ antagonist which may create
Ketamine 5 mg/kg IM difficulties if additional opiates are required.
3 Medetomidine 20 μg/kg and buprenorphine 10-20 μg/kg IM This combination provides superior analgesia with regards to both
Wait 20 minutes depth and duration compared with combinations 1 and 2.
Ketamine 2-5 mg/kg IM
4 Medetomidine 20 μg/kg and methadone 0.2 mg/kg IM This produces profound analgesia.
Wait 10 minutes Additional methadone doses (0.2 mg/kg IM or SC) may be given in
Ketamine 2 mg/kg IM response to postoperative pain scoring.

The combinations listed are sufficient to allow endotracheal intubation and surgery of approximately 20-30 minutes duration. Gaseous agents (eg, isoflurane) will be required to deepen or extend the
anaesthetic period.
IM Intramuscular, SC Subcutaneous

requirement for anaesthetic drugs. There are a • Reduces the dose of alpha-2 agonist required
number of reasons for this, including a faster which is likely to improve cardiac output,
metabolism and clearance rate. Intramuscular (IM) • Is an appetite stimulant (prompt feeding on
alpha-2 agonist/ketamine combinations may be recovery reduces the risk of hypoglycaemia),
useful in very small patients where intravenous • Provides amnesia meaning that kittens are less
access is problematic (Table 6). likely to be distressed by the experience of hos-
pitalisation,
Cat
• Reduces the likelihood of post-reversal (atipa-
The Kitten Quad – an app that enables vets to
mezole) excitation.
calculate doses of an unlicensed quad anaesthetic
■■Ketamine is the intramuscular induction agent
combination to carry out early neutering in kittens –
developed at the RSPCA Greater Manchester Animal which:
Hospital comprises medetomidine, ketamine, • Increases heart rates which have been reduced
midazolam and an opioid (buprenorphine or by the alpha-2 agonist,
methadone). • Contributes to multimodal analgesia,
The key features of the combination are: • Has as a wide therapeutic index.
■■The quad combination causes a rapid loss of
consciousness; this improves throughput, allows Surgery
for rapid establishment of a patent airway with Males
intubation and reduces the risk of hypothermia. Dogs
■■Body surface area dosing is used for calculation of Puppies may be castrated using a standard
drug volumes. This improves reliability in small prescrotal midline approach. The small, mobile
patients with rapid metabolic rates. testes should be gently pushed cranially to a
■■The intramuscular combinations are easily common incision. Alternatively, as per cats, small
administered to small kittens where intravenous puppies may be castrated through scrotal incisions.
access is challenging. The incision should be closed routinely with 1.5
■■Midazolam, which is not licensed for veterinary metric poliglecaprone (Monocryl; Ethicon) or an
use, offers the following: appropriately sized absorbable suture material
and tissue glue applied to prevent self or littermate
wound trauma (Box 1).
Table 7: Volumes of drugs used in the buprenorphine and methadone quads Both testes are usually descended into the
scrotum by 12 to 14 weeks of age in dogs. It is
Weight of kitten (kg) Volume of each agent in Volume of each agent in
sensible to postpone castration of cryptorchid dogs
buprenorphine quad (ml) methadone quad (ml)
until after puberty; there is an increased surgical
0.5 0.04 0.03
risk associated with removal of retained testicles
1.0 0.06 0.05 and larger testes may be easier to palpate when in
1.5 0.08 0.07 an inguinal location or identify at coeliotomy.
2.0 0.1 0.08
Cats
2.5 0.12 0.1
It is important to note that many kittens will have
3.0 0.13 0.11 small, relatively mobile prepubertal testes which
Concentrations of drugs used in the ‘quad’ are: medetomidine 1 mg/ml, ketamine 100 mg/ml, buprenorphine 300 ‘fix’ scrotally when larger at sexual maturity. As
μg/ml, methadone 10 mg/ml, midazolam 5 mg/ml
with canine patients, cryptorchid cats should

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Table 8: Recommendations for timing of neutering in the dog and cat

Ownership Dog Cat
Owned, private client Thorough discussion with the client is Ensure cats are vaccinated before
required to determine the most appropriate admission; therefore, neuter at 12-16 weeks
time for neutering depending on the of age.
individual animal.
For example, a large breed, cryptorchid dog
should be neutered at puberty, compared
with a small breed, female dog that may be
neutered after completion of the primary
vaccine course.
Owned, charity client Owner compliance is often poor. Neutering Owner compliance is often poor. Neutering
can be combined with vaccination, can be combined with vaccination,
microchipping and other minor procedures microchipping and other minor procedures
in cases where a thorough clinical in cases where a thorough clinical
examination has been performed and the examination has been performed and the
animal has received endo- and ectoparasite animal has received endo- and ectoparasite
treatment. treatment.
However, the same discussions are
required as for dogs owned by private
clients.

Feral Trapped, feral kittens should be neutered

regardless of age. Size is likely to be
the restricting factor (ie, location of
testes in patients less than 300 g can be
challenging).
Shelter animals Animals should be neutered before rehoming (this prevents issues with failure to comply
with charity neutering policies).

be castrated after puberty for the same reasons on entry to the abdomen and this is a common,
previously described. incidental finding in both puppies and kittens.
Bilateral scrotal incisions are made directly over Haemostasis in puppies and kittens is relatively
the testes and castration can be achieved by (Box 1): simple. Vessels in the skin, subcutaneous fat and
■■Ligation of the spermatic bundle with absorbable linea alba are small and often insignificant. The
suture material (open or closed castration), ovarian vessels can be ligated with simple ligatures
■■Tying the spermatic bundle on itself with with an appropriately sized suture material. The
haemostats (open or closed castration) , vaginal stump is ligated by a simple ligature or a
■■Tying the ductus deferens with the spermatic modified Miller’s knot.
vessels (open castration). The linea alba can be closed with an interrupted
or continuous polydioxanone pattern and the
The skin incisions are left to heal by secondary subcutaneous fascia closed with a continuous
intention.
Females
BOX 1: STEPS FOR PERFORMING A PREPUBETAL CASTRATION
Dogs
A midline approach caudal to the umbilicus should
be used for ovariectomy or ovariohysterectomy
in the bitch. We would locate the incision further
caudally in younger patients. For example, the
centre of the incision may be halfway between the
umbilicus and pubic brim in a six-week-old female.
The surgical incision is likely to be smaller and
surgical time shorter for ovariectomy. In prepubertal
patients, the ovaries may be readily elevated for the
following reasons:
■■The ovarian suspensory ligament seems more
elastic,
■■The abdomen is relatively shallow and usually
contains less fat. Step 1: Make bilateral scrotal Step 2: Tie the ductus deferens
incisions. with the spermatic vessel during
Small volumes of serous intra-abdominal fluid (low open castration.
cellularity and low specific gravity) may be noted

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BOX 2: STEPS FOR PERFORMING A PREPUBERTAL SPAY

Step 1: Place the animal on a heated table or heat pad and position Step 2: Make a small (1-2 cm) incision two-thirds the distance from
it in dorsal recumbency with its hind limbs extended. Perform a umbilicus to pubic brim. Dissect the subcutaneous fat to expose the
conservative clip to minimise patient cooling. linea alba.

Step 3: With a scalpel, make a Step 4: Locate and gently elevate Step 5: Starting with the left side, expose the ovary and place three
stab incision on the linea alba the uterine horn. small haemostats before ligating the ovarian pedicle.
to allow entry to the abdominal
cavity. Extend this using
metzenbaum scissors.

Step 8: Intradermal closure Step 7: Close the linea alba with

can be achieved by using an interrupted or continuous
Step 6: Using haemostats, separate
poliglecaprone ended with an polydioxanone pattern and
the broad and round ligament from the
Aberdeen knot. Tissue glue may the subcutaneous fascia with
uterus - ligation is seldom required in
be advisable for extra protection a continuous poliglecaprone
prepubertal kittens.
in litters of puppies and kittens pattern, taking occasional ‘bites’
Steps 5 and 6 are repeated with the right
(eg, where there is mutual of the muscle sheath.
ovary. The cervix is double ligated.
grooming or suckling).

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poliglecaprone pattern taking occasional bites of 31, 442-448

the muscle sheath (this reduces the likelihood of DESAPIO, A., VAN DE COEVERING, P., WILLIAMS, J. G. & OTHERS (2005)
Effects of early-age gonadectomy on a male guide dog population.
seroma formation). Intradermal closure can be
Proceedings of the 4th International Working Dog Breeding Conference.
achieved by using poliglecaprone ended with an Melbourne, Australia, 23-27 January, 2005
Aberdeen knot. Tissue glue may be advisable for DORN, C. R., TAYLOR, D. O. N., FRYE, F. L. & HIBBARD, H. H. (1968)
extra protection in litters of puppies and kittens. Survey of animal neoplasms in Alameda and Contra Costa Counties,
California. I. Methodology and description of cases. Journal of the
National Cancer Institute 40, 295-305
Cats DOWNES, M. J., DEVITT, C., DOWNES, M. T. & MORE, S. J. (2015)
The landmarks for the midline incision in kittens Neutering of cats and dogs in Ireland; pet owner self-reported percep-
are as follows: tions of enabling and disabling factors in the decision to neuter. PeerJ
3, e1196
■■Kittens less than 12 weeks old: make an incision
HART, B. L., HART, L. A., THIGPEN, A. P. & WILLITS, N. H. (2014) Long-
two-thirds the distance from umbilicus to pubic term health effects of neutering dogs: comparison of labrador retrievers
brim. with golden retrievers. PLoS ONE 9, e102241
■■Kittens more than 12 weeks old: make an incision
JOHNSTON, S. D., ROOT KUSTRITZ, M. V. & OLSON, P. S. (2001) Canine
and Feline Theriogenology. Saunders
half the distance from umbilicus to pubic brim. MCCANN, T. M., SIMPSON, K. E., SHAW, D. J., BUTT, J. A. & GUNN-
MOORE, D. A. (2007) Feline diabetes mellitus in the UK: the prevalence
Generally, a 10 to 20 mm surgical incision is within an insured cat population and a questionnaire-based putative
risk factor analysis. Journal of Feline Medicine and Surgery 9, 289-299
adequate. The bladder may be carefully reflected
MCGREEVY, P. D., WILSON, B., STARLING, M. J. & SERPELL, J. A. (2018)
to facilitate identification of the uterus. The kitten Behavioural risks in male dogs with minimal lifetime exposure to
can be spayed routinely; the ovaries should be gonadal hormones may complicate population-control benefits of
exposed starting with the left ovary, and clamped desexing. PLoS ONE 13, e0196284
OVERLEY, B., SHOFER, F. S., GOLDSCHMIDT, M. H., SHERER, D. &
with three small haemostats before ligation. SORENMO, K. U. (2005) Association between ovariohysterectomy and
The cervix should be double ligated. Particular feline mammary carcinoma. Journal of Veterinary Internal Medicine 19,
care must be taken to ensure tissue handling is 560-563
minimised and performed in a gentle manner POLLARI, F. L., BONNETT, B. N., BAMSEY, S. C., MEEK, A. H. & ALLEN,
D. G. (1996) Postoperative complications of elective surgeries in
given the friable nature of the reproductive tract. dogs and cats determined by examining electronic and paper medical
Abdominal closure is achieved as described above records. Journal of the American Veterinary Medical Association 208,
for puppies, with necessary alterations to the size 1882-1886
of suture materials selected (Box 2). POLSON, S., TAYLOR, P. M. & YATES, D. (2014) Effects of age and repro-
ductive status on postoperative pain after routine ovariohysterectomy
in cats. Journal of Feline Medicine and Surgery 16, 170-176
Summary PORTERS, N., DE ROOSTER, H., VERSCHUEREN, K., POLIS, I. & MOONS,
The evidence to support prepubertal gonadectomy in C. P. H. (2014) Development of behavior in adopted shelter kittens
after gonadectomy performed at an early age or at a traditional age.
cats is highly persuasive. Cats are efficient and largely
Journal of Veterinary Behavior 9, 196-206
uncontrolled breeders and they exhibit significant ROOT KUSTRITZ, M. V. (2014) Pros, cons, and techniques of pediatric
risk behaviours which often respond to neutering. neutering. Veterinary Clinics of North America: Small Animal Practice
Prepubertal gonadectomy is a low-risk procedure 44, 221-233
ROOT KUSTRITZ, M. V., JOHNSTON, S. D., JOHNSTON, G. R. & OLSON, P.
when performed appropriately; complications are N. (1996) The effect of prepuberal and postpuberal gonadectomy on
minimised by appropriate patient selection, the use penile extrusion and urethral diameter in the domestic cat. Veterinary
of safe and efficient anaesthetic protocols, minimally Radiology and Ultrasound 37, 363-366
traumatic surgical techniques, careful monitoring ROWE, C., BROWNE, W. J., CASEY, R. A., GRUFFYDD-JONES, T. J. &
MURRAY, J. K. (2017) Early-life risk factors identified for owner-reported
and provision of adequate analgesia. feline overweight and obesity at around two years of age. Preventive
Prepubertal gonadectomy in dogs is open to much Veterinary Medicine 143, 39-48
wider debate. Randomised studies to compare SALMERI, K. R., BLOOMBERG, M. S., SCRUGGS, S. L. & SHILLE, V.
prepubertal, conventional and non-neutered dogs (1991) Gonadectomy in immature dogs: effects on skeletal, physi-
cal, and behavioral development. Journal of the American Veterinary
are unavailable. For owned animals, it is essential Association 198, 1193-1203
that the risks and benefits for each individual SCHNEIDER, R., DORN, C. R. & TAYLOR, O. N. (1969) Factors influencing
animal are discussed to determine the most mammary cancer development and postsurgical survival. Journal of the
National Cancer Institute 43, 1249-1261
appropriate strategy for neutering based on breed,
SERPELL, J. A. & HSU, Y. (2005) Effects of breed, sex, and neuter status
lifestyle, temperament, longevity expectations, on trainability in dogs. Anthrozoös 18, 196-207
neoplasia risk and client preferences. SMITH, A. N. (2003) Hemangiosarcoma in dogs and cats. Veterinary
Clinics of North America: Small Animal Practice 33, 533-552
SPAIN, C. V., SCARLETT, J. M. & HOUPT, K. A. (2004) Long-term risks and
benefits of early-age gonadectomy in dogs. Journal of the American
References Veterinary Medical Association 224, 380-387
STUBBS, W. P., BLOOMBERG, M. S., SCRUGGS, S. L., SHILLE, V. M. &
ALLAWAY, D., GILHAM, M., COLYER, A. & MORRIS, P. (2017) The impact LANE, T. J. (1996) Effects of prepubertal gonadectomy on physical and
of time of neutering on weight gain and energy intake in female kittens. behavioural development in cats. Journal of the American Veterinary
Journal of Nutritional Science 6, doi: 10.1017/jns.2017.20 Medical Association 209, 1864-1871
BYRON, J. K., TAYLOR, K. H., PHILLIPS, G. S. & STAHL, M. S. (2017) WILSON, J. L., GRUFFYDD-JONES, T. J. & MURRAY, J. K. (2017) Risk fac-
Urethral sphincter mechanism incompetence in 163 neutered female tors for road traffic accidents in cats up to age 12 months that were
dogs: diagnosis, treatment, and relationship of weight and age at neu- registered between 2010 and 2013 with the UK pet cat cohort (‘Bristol
ter to development of disease. Journal of Veterinary Internal Medicine Cats’). Veterinary Record doi:10.1136/vr.103859

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SELF-ASSESSMENT: PREPUBERTAL NEUTERING IN DOGS AND CATS

In Practice partners with BMJ OnExamination to host self-assessment quizzes for each clinical article. These can be
completed online at inpractice.bmj.com

1. Which of the following statements regarding anaesthesia c) Large breed male puppies
in puppies and kittens is false? d) Mixed breed puppies
a) Dosing kittens using body surface area improves
reliability 3. Prepubertal neutering is:
b) Hypothermia and hypoglycaemia may significantly a) A high risk procedure beyond the scope of the average
delay recovery from anaesthesia practitioner
c) A multimodal approach is likely to improve both safety b) An essential tool for the control of unplanned breeding
and pain prevention in owned cats
d) Puppies and kittens usually recover more slowly than c) A cause of early growth plate closure in puppies
adults d) Likely to decrease life expectancy in dogs

2. Arguments supporting prepubertal neutering are least 4. True or false. All forms of cancer are less likely following
persuasive in: prepubertal gonadectomy in the dog.
a) Male kittens a) True
b) Small breed bitches b) False
Answers: (1) d, (2) c, (3) b, (4) b

Going on parental
leave or have a
vet who is?
Download the BVA guide to
maternity and paternity leave
for advice for employers,
employees and locums.
www.bva.co.uk/guides

298 September 2019 | IN PRACTICE

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 In Practice: first published as 10.1136/inp.l5007 on 5 September 2019. Downloaded from http://inpractice.bmj.com/ on September 22, 2019 at James Cook University. Protected by copyright.
Companion animal

SELF-ASSESSMENT: PREPUBERTAL NEUTERING IN DOGS AND CATS

In Practice partners with BMJ OnExamination to host self-assessment quizzes for each clinical article. These can be
completed online at inpractice.bmj.com

1. Which of the following statements regarding anaesthesia in

puppies and kittens is false? 3. Prepubertal neutering is:
a) Dosing kittens using body surface area improves reliability a) A high risk procedure beyond the scope of the average
b) Hypothermia and hypoglycaemia may significantly delay practitioner
recovery from anaesthesia b) An essential tool for the control of unplanned breeding in
c) A multimodal approach is likely to improve both safety and pain owned cats
prevention c) A cause of early growth plate closure in puppies
d) Puppies and kittens usually recover more slowly than adults d) Likely to decrease life expectancy in dogs

2. Arguments supporting prepubertal neutering are least persuasive 4. True or false. All forms of cancer are less likely following
in: prepubertal gonadectomy in the dog.
a) Male kittens a) True
b) Small breed bitches b) False
c) Large breed male puppies
d) Mixed breed puppies
Answers: (1) d, (2) c, (3) b, (4) b

Going on parental
leave or have a
vet who is?
Download the BVA guide to
maternity and paternity leave
for advice for employers,
employees and locums.
www.bva.co.uk/guides

298 September 2019 | IN PRACTICE

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