DL - to spay or castrate? Flashcards
What are reasons not to spay?
CLINICAL juvenile vaginitis, congenital urethral sphincter mechanism incompetence (SMI)
OTHER: unable to give informed consent, neutering may be considered by some as a mutilation,
What are reasons for neutering?
Prevention of unwanted litters and pregnancy
Prevention of pre-oestrous
Modify behaviour
Reduce or prevent disease affecting sex organs and accessory sex organs
What is prevented with spaying?
social inconvenience of oestrous, pyometra, vaginal prolapse, dystocia, foetal death, abortion, eclampsia, uterine torsion, uterine rupture, uterine prolapse, metritis, post-partum haemorrhage, mastitis and unwanted litters are ALL PREVETNED.
What are the advantages of OVH?
Incidence of mammary tumours reduced in dogs and cats
• 3-7 more common in Entire N bitch
• 0.5% cancer risk if neutered pre-pubertally
• 8% cancer risk post first season
• 26 % cancer risk post 2nd season
• 3+ seasons no effect Schneider 1969
b. Earlier neutering – maximal effect
c. Various studies also suggest reduced risk of recurrence and improved survival of dogs that are speyed as an adjunctive to mammary tumours
d. Recent evidence – risk is associated with breed
e. Recent systematic review (Beauvais 2012, JSAP 53, 314) concluded the published evidence is weak
What are the disadvantages of OVH?
a. Risk of surgical complication (haemorrhage – biggest risk, wound breakdown, infection, retained ovarian remnant, acquired ectopic ureter, ureteral injury, stump granuloma
b. In dogs associations between neutering and urinary incontinence, weight gain, increased risk of some type of cancer, CCL rupture, anaesthetic death, peri-vulval dermatitis, atrophic vaginitis, endocrine alopecia.
c. Some cancers more common in neutered dogs
Which cancers are more common in neutered dogs?
BLADDER – TCT affecting bladder and urethra of male and female dogs has been found to be increased 2-4 times after gonadectomy, specific breed predispositions
SPLEEN AND HEART – both haemangiosarcoma are increased after gonadectomy increased by an average of 2.4 times, specific breed predispositions.
LYMPHOMA – intact female dogs have a significantly lower risk of developing lymphoma than other sex combinations. Proposed that oestrogen offers a protective effect.
SKIN – suggestion of increased risk of cutaneous MCT in NF dogs versus entire bitches
PROSTATE – rare but usually malignant carcinoma, castration not protective and increased risk 2.4-4.3 times has been found in castrated dogs compared to intact dogs.
What are the pros/cons of pre-pubertal neutering?
PROS OF PREPUBERTAL NEUTERING – reduced mammary tumours (can kill dogs), no opportunity for pregnancy, pyometra or pseudopregnancy, surgery quicker and easier, recovery faster? Hormonally related learned behaviour not established
CONS OF PREPUBERTAL NEUTERING procedure more risky for inexperience surgeon, SMI? - contradictory evidence, possible increased risk of orthopaedic disease (osteosarcoma, CCL rupture, hip dysplasia), infantile vulva?? Coat fluffier??? More dominant behaviour?? PROS OF PREPUBERTAL NEUTERING – reduced mammary tumours (can kill dogs), no opportunity for pregnancy, pyometra or pseudopregnancy, surgery quicker and easier, recovery faster? Hormonally related learned behaviour not established
Why is is not advisable to neuter during oestrous if at all possible?
greater risk of haemorrhage (increased blood supply), organs more friable. Only really in unplanned situations. Be more careful with tissue handling and ligature quality
How long should you want after oestrous before spaying and why?
AVOID 28D TO APPROX. 4 MONTHS POST OVULATION as risk of inducing false pregnancy or in bitches with pseudocyesis (phamtom pregnancy) – the condition becoming permanent, due to sudden drop in P4 and rise in PRL loss of negative feedback to pituitary.
What are the 2 main spaying techniques?
OVARIECTOMY: evidence available that it is an effective method for elective neutering, shorter and less major surgery with OE reduced risk, reduced risk of ureteral injury less ligature (foreign material) and ? reduced risk of bleeding, less trauma if done laparoscopically, no increased risk of pyometra, risk of urinary incontinence not reduce, laparoscopy expensive, treatment with exogenous hormones may affect remaining reproductive tract.
OVARIOHYSTERECTOMY (OVH): UK vets familiar with OVH, minimal risk of future problems if bitch receives exogenous hormones, failure to remove ovary for both techniques.
How can oestrous be controlled non-surgically?
- PROGESTINS (proligesone = Delvosterone= safest found in most SA practices, Medroxyprogesterone acetate = Promone-E, megestrol acetate = Ovarid)
- ANDROGENS (testosterone +Durateston) used for greyhound racing to prevent them coming into season, not really used in practice
- PRONLONGED GnRH AGONISTS AND ANTAGONISTS – non licensed in UK for this use, pyometra still possible (P4 still present), no data on mammary disease incidence
- More information at NOAH compendium
- Owner has to be dedicated – injections (about every 5 months for Delvosterone) for control or pills.
How can pregnancy be controlled post-mating, medically?
- Progesterone antagonists (Aglepristone)
- Oestrogens
- (PRL antagonists)
- (Prostaglandins)
- (PRL antagonists and prostaglandins)
- (Prolonged GnRH agonists and antagonists)
- (Synthetic anti-oestrogens)
How reliable is castration at stopping/reducing aggression?
Behavioural signs reduced by 60% following orchidectomy (objectional sexual behaviour, itnermale aggression, roaming abnormal urination)
Another study concluded that castration may be effective in decreasing aggression in some dogs but 33% have a marked improvement (Neilson et al 1997)
But not predictable or reliable for an individual dog
What is prevented with castration?
What is decreased with castration?
PREVENTED: testicular neoplasia, torsion, epididymitis, testicular tumours, testicular trauma, other testicular disease, unwanted litters
DECREASED urine marking, roaming, inter-male aggression, mounting/copulatory behaviour (if pre-pubertal), reduction in prostatic disease, reduced incidence of perineal hernia)
What are the disadvantages of castration?
SURGICAL COMPLICATIONS – haemorrhage, wound breakdown, infection, scrotal bruising and swelling, urethral injury, incomplete orchidectomy, inadvertant prostatectomy (dog)
OTHER RISKS – urinary incontinence, weight gain, anaesthetic death, prostatic carcinoma not prevented in dog, increased risk of neoplasia, increased risk of orthopaedic disease, delayed physeal closure (because related to reproductive hormones
What are non-surgical alternatives to castration?
Therapeutic trial with progestagens, behaviour modification training or combination of these.
GnRH analogue - Deslorelian (Suprelorin) not licensed for behavioural modification and effect unknown.
What is defined as early age neutering?
Early age neutering is defined as <12 weeks. (Murray et al Vet Rec 2008). Some animals are neutered really young (6-7 weeks).
What are additional considerations when neutering a young animal?
ANAESTHETIC CONSIDERATIONS – more prone to cold, risk of hypoglycaemia (consider giving glucose in IV fluids), more sensitive to drugs (see literature)
SURGICAL CONSIDERATIONS – procedures the same, gonads and RT small, tissues delicate, less fat and easier to see and ligate vessels, rapid recovery.
What are the long-term effects of neutering animals early?
Many recent studies
Overall benefits on pet population
BUT no less likely to be given up by adopters
Generally considered safe and desirable with minimal long term health effects but there are some consequences
Approx. 50 000 animals are euthanized every year in the UK because not wanted by rehoming centres.
What are the advantages of early neutering?
Max effect on population control
At preventing some diseases (Mammary tumours, RT disease)
Max effect on preventing socially acceptable behaviours
Benefit for adopters
Cheaper – animals smaller so need less drugs, procedure quicker
What are the disadvantages of early neutering?
Risk of infectious disease if not fully vaccinated
Potential loss of gene pool diversity
Early neutering suggested to increase risk of uretheral sphincter mechanism incompetence (USMI) in the bitch, some cancers in the dog, some other orthopaedic diseases in dogs and cats
What are the biologic effects of early neutering?
Secondary sex characteristic don’t develop – immature external genitalia
Delay in growth plate closure – longer long bones
Juvenile behaviours – less aggression
What is the effect of early neutering on behaviour? (dogs/cats)
Cats. Males – decreased aggression to vets, sexual behaviour and urine spraying, increased hiding. Males and females – decreased hyperactivity, increased shyness
Dogs – males and females - decreased separation anxiety, escaping behaviours, inappropriate elimination when frightened, increased noise phobias and sexual behaviours.
Which orthopaedic diseases are associated with early neutering?
More prone to growth plate fractures
Hip dysplasia
CCL rupture due to abnormal angulation of the tibial plateau
More research needed
True/false - there is a short term risk of destabilising diabetes with a GA.
True
Why are Doberman’s risky to spay?
vWDs
Which breeds are most susceptible to vWD?
Doberman Pinscher, Golden Retriever, Shetland Sheepdog, Rottweiler, Miniature Schnauzer, German Shepherd, German Short-Haired Pointer, Standard Poodle, and Scottish Terrier.
What is the ICC?
International Cat Care (formerly FAB)
What is USMI?
Urinary smooth muscle incontinence
What alternatives are there to neutering for contraception? (FEMALE)
Responsible pet ownership – prevent mating
Other surgeries – vasectomy
Use of drugs to – control oestorus, induce abortion, suppress spermatogenesis in male.
Physical device – IUD reported in bitches
What alternatives are there to neutering for contraception? (MALE)
Prolonged GnRH agonist – Deslorelin (Suprelorin), licensed for use in the dog and ferret
Others unreliable and NOT licensed for this in UK: progestogens, androgens, progestogens/androgens, prolonged GnRH antagonists
Other physical, chemical and immunotherapeutic techniques subject of research which have not yet been translated into clinical practice.
