Contraception Flashcards
Why is empirical calculation of risk vs benefit so difficult for contraception?
- Incidence, severity, and method for diagnosis of disease may be uncertain
- Frequent confounding variables
- Contraception may lead to effects on longevity and body weight which themselves affect frequency of certain disease
Population benefits of contraception
- Reduced overpopulation
- Reduced feral animal population (reduced predation on wild animals, reduced transmission of disease through reservoirs; reduced injuries and auto accidents)
- reduced euthanasia of unwanted animals
Population: risks of contraception
- Population risks are infrequently discussed
- Decreased genetic diversity (????)
- Ecosystem and environmental effects
- Effects on animal industries including veterinary medicine
- Loss of models of human disease
Risks of breeding and pregnancy for the individual
- Behavior associated with being intact (mating related wandering; territorial based fighting; aggression; injury during copulation; infection; STD)
- Medical problems during pregnancy
- Dystocia
- Post-partum problems
Benefits of contraception for the individual
- Reduction of breeding and pregnancy risks
- Reduce undesired behavior and traits
- Increased life expectancy
- Reduced diseases of reproductive organs in general
Which contraception surgeries are proven and effective?
- Ovariectomy
- Ovariohysterectomy
- Castration
- Recently, positive seeming reviews for sutureless scrotal castration in dogs
Why is it usually not recommended leaving functioning gonads with ligation or transection of oviducts and ductus deferens as an alternative to castration?
- reproductive behavior and disease risk often don’t change much
Risks of surgery and anesthesia
- Intubation, hypothermia, hemorrhage, pain, surgical error, dysrhythmia, GDV, drug error, delayed healing
Benefits of prepubertal surgery?
- Gonadectomy performed before release from animal shelters helps with population control
- Early age pregnancy is avoided
- Mammary neoplasia (the most common cancer in dogs) is significantly reduced
Concerns with prepubertal surgery?
- Failure of gonadal hormone influenced development (vulva, penis, long bones)
- Anesthesia of small patients
Mammary neoplasia incidence in spayed vs intact females
- Most common tumor in dogs
- 7x more likely in intact female compared to spayed female
- 0.5% incidence if spayed prior to first estrus
- Mammary gland development during diestrus diminishes protective effect of spaying with each subsequent estrus, but there is still some risk reduction if spayed at any time of life
Mammary neoplasia malignancy in dogs vs cats
- Malignant in about 50% of dogs and 90% of cats
Other neoplasias that are decreased in spayed/castrated animals?
- Ovarian cancer is decreased
- Testicular cancer is reduced
Which cancers may have a relative risk increase in spayed and castrated animals?
- Prostate usually has a 2.84 relative risk increase
- Urinary bladder transitional cell carcinoma may have an increased risk as well
- Hemangiosarcoma has slight increase
- Osteosarcoma has slight increase too
Caveats of increased risks of neoplasia in altered animals
- cause and effect is very unclear; lots of confounding variables like environment, increased longevity, and increased weight
- Persistent LH elevation and other hormones of hypothalamus and pituitary gland may play a significant role
What happens to luteinizing hormones when you spay or neuter a dog?
- Increase in LH due to you taking away the negative feedback of estrogen
Metabolic diseases associated with castration
- Increased diabetes mellitus in Burmese cats
- Due to increased insulin sensitivity?
- Hypothyroidism in dogs potentially due to persistent hypothalamic stimulation and persistent GnRH
Orthopedic disease and castration
- Estrogen causes closure of long bone growth plates in both females and males (testosterone converted to estrogen)
- Gonadectomy prior to normal time of closure leads to continued bone growth, asymmetry of bones, laxity of joints, overly straight limbs
- Hip dysplasia, ACL injury, and growth plate fractures may increase due to early surgery (obesity may be a factor though too)
Genitourinary problems associated with early castration
- Incidence of estrogen-responsive urinary incontinence in females is 4.9 to 20%
- More common in early age spay (3 months)
- Obesity can be a factor
- Small and inverted vulva more common in early age spay as well
- Persistent frenulum in feline males with early age neuter
- May increase cystitis?
Effect of gonadectomy on uterine, ovarian, and vaginal neoplasia?
- Prevents
Effect of gonadectomy on perianal gland tumor?
Decreased
