Contraception Flashcards
Risks of Breeding and Pregnancy
Territorial based fighting Aggression during breeding season Injury during copulation Infection Sexually transmitted disease Medical problems during pregnancy Dystocia Post-partum problems
Benefits of Contraception
Reduction of breeding and pregnancy risks
Reduce undesired behaviors
Increases life expectancy
Reduces disease of reproductive organs
Ovarioectomy
Removal of ovaries
Ovariohysterectomy
Removal of ovaries and uterus
Ovarioectomy and ovariohysterectomy problem
Removal of ovaries than no longer can continue negative LH feedback; LH consistantly high
LH receptors are located in numerous tissues; unsure what elevated LH levels do to effect other tissues however
Hysterectomy
Removal of uterus
Now ovaries can respond to LH, will not get bloody discharge b/c no uterus
Higher chance of developing mammary neoplasia (can be quite common)
Autoligation
Sutureless scrotal castration
Must be in cat or very small dog
Prepubertal Surgery
Benefits
Population control
Significantly reduced mammary neoplasia
When is puberty reached?
When animal has reached 70% of adult bodyweight
Prepubertal Surgery
Concerns
Failure of gonadal hormone influenced development (vulva, penis, long bones)
Long bone development is driven by estrogen; long bones get longer because the physis does not close at proper time
Increased chance of obesity
Mammary Neoplasia
Most common tumor in dog
7x more likely in intact female
0.5% incidence if spayed prior to first estrus
Mammary gland development during diestrus diminishes protective effect of spaying with each subsequent estrus
Mammary Neoplasia
Canine vs. Feline
Canine: 50% malignant
Feline: 90% malignant
What neoplasias increase (risk) with gonadectomy?
Why?
Prostate Transitional cell carcinoma Hemangiosarcoma (low incidence) Osteosarcoma (low incidence) \+/- lymphoma \+/- mast cell tumor
Why?
Suspected; persistent elevation of LH and other hormones of hypothalamus and pituitary gland may have significant role
Metabolic Disease in Neutered Animals
Increased diabetes mellitus in Burmese cats (decreased sensitivity to insulin and/or obesity)
Hypothyroidism in dogs reported to increase in some studies (persistent hypothalamic stimulation and persistent GnRH may affect TRH and TSH)
Orthopedic Disease in Neutered Animals
Estrogen causes closure of long bone growth plates (males and females)
Gonadectomy prior to closure causes continued bone growth, asymmetry of bones, laxity of joints
May increase chance of hip dysplasia, ACL injury, growth plate fractures
Genito-Urinary Problems in Neutered Animals
Estrogen-responsive urinary incontinence in spayed females (usually if spayed early)
Inverted vulva (if spayed young)
Kinds of non-surgical contraception
Hormones GnRH (agonist, antagonist, receptors) Affects FSH and LH Immuno-contraception Chemical sterilant
Progestins
What is it? How does it work?
Contraceptive
Mimics progesterone => body thinks female is pregnant
Not recommended because of frequent serious side effects (pyometra, diabetes mellitus, increased mammary tumors, adrenocortical suppression)
Androgens for female contraception
Examples
What does it do?
Adverse effects?
Tesosterone and mibolerone
Causes negative feedback blocking LH release -> delays estrus
Idiosyncratic liver failure
Masculinization effects
GnRH Agonist
Examples
What does it do?
Deslorelin implants (licensed for use outside the US)
Initial stimulation then prolonged suppression of GnRH => enters estrus than will get out of it
Lasts months to years; individual dependent
FDA approved for horses and adrenal disease in ferrets ONLY
GnRH Antagonists
Effective within short time after administration; requires frequent administration
Blocks pituitary GnRH receptors
Not available in veterinary medicine yet
GnRH Vaccines
Stimulates antibodies to GnRH (small molecule poorly recognized by immune system) - inconsistent however so not available for feline and canine
Effective as one-injection for several years (1-4): USDA use in white-tailed deer
Chemical Sterilant
Examples
Zinc gluconate and arginine (approved in US)
Calcium chloride (not approved in US)
Chemical Sterilant
How it works
Testicular degeneration and permanent sterility
Intra-testicular injection (extremely painful)
Sedation and analgesia
Castrate after or close to musculoskeletal maturity which is…
7-8 months for small breed dogs
2 years for large breed dogs (can do at 12-14 months)
