1
Q
Why is empirical calculation of risk vs benefit so difficult for contraception?
A
- 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
2
Q
Population benefits of contraception
A
- 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
3
Q
Population: risks of contraception
A
- 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
4
Q
Risks of breeding and pregnancy for the individual
A
- 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
5
Q
Benefits of contraception for the individual
A
- Reduction of breeding and pregnancy risks
- Reduce undesired behavior and traits
- Increased life expectancy
- Reduced diseases of reproductive organs in general
6
Q
Which contraception surgeries are proven and effective?
A
- Ovariectomy
- Ovariohysterectomy
- Castration
- Recently, positive seeming reviews for sutureless scrotal castration in dogs
7
Q
Why is it usually not recommended leaving functioning gonads with ligation or transection of oviducts and ductus deferens as an alternative to castration?
A
- reproductive behavior and disease risk often don’t change much
8
Q
Risks of surgery and anesthesia
A
- Intubation, hypothermia, hemorrhage, pain, surgical error, dysrhythmia, GDV, drug error, delayed healing
9
Q
Benefits of prepubertal surgery?
A
- 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
10
Q
Concerns with prepubertal surgery?
A
- Failure of gonadal hormone influenced development (vulva, penis, long bones)
- Anesthesia of small patients
11
Q
Mammary neoplasia incidence in spayed vs intact females
A
- 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
12
Q
Mammary neoplasia malignancy in dogs vs cats
A
- Malignant in about 50% of dogs and 90% of cats
13
Q
Other neoplasias that are decreased in spayed/castrated animals?
A
- Ovarian cancer is decreased
- Testicular cancer is reduced
14
Q
Which cancers may have a relative risk increase in spayed and castrated animals?
A
- 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
15
Q
Caveats of increased risks of neoplasia in altered animals
A
- 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
16
Q
What happens to luteinizing hormones when you spay or neuter a dog?
A
- Increase in LH due to you taking away the negative feedback of estrogen
17
Q
Metabolic diseases associated with castration
A
- Increased diabetes mellitus in Burmese cats
- Due to increased insulin sensitivity?
- Hypothyroidism in dogs potentially due to persistent hypothalamic stimulation and persistent GnRH
18
Q
Orthopedic disease and castration
A
- 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)
19
Q
Genitourinary problems associated with early castration
A
- 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?
20
Q
Effect of gonadectomy on uterine, ovarian, and vaginal neoplasia?
A
- Prevents
21
Q
Effect of gonadectomy on perianal gland tumor?
A
Decreased
22
Q
Effect of gonadectomy on lymphoma?
A
- Increased
23
Q
Effect of gonadectomy on mast cell tumor?
A
- Increased
24
Q
Effect of gonadectomy on cystitis
A
- Increased
25
Effect of gonadectomy on perineal hernia
Decreased in males
26
Effect of gonadectomy on Diabetes mellitus
- Increased but may be related to obesity
27
How do progestins act as contraception?
- mimic effects of progesterone and simulate pregnancy
28
Recommendation for progesterone as a hormonal control of contraception?
- Not recommended
- Frequent serious side effects
- Pyometra, diabetes mellitus, increased mammary tumors
- Adrenocortical suppression
29
Which androgens can be used for female contraception?
- Testosterone and mibolerone
30
How do mibolerone and tesosterone act as contraception?
- Cause negative feedback that blocks LH release
31
How effective are testosterone and mibolerone?
- Effective
32
Label of tesosterone and mibolerone
- Testosterone is off-label
| - Mibolerone is compounded
33
Negative effects of androgens
- Masculinization efefcts in females
| - Idiosyncratic liver failure can occur
34
GnRH agonist
- Deslorelin implants effective in canine and feline
| - Licensed outside of the US
35
How does a GnRH agonist work?
- Initial stimulation then suppression
36
FDA approval of GnRH agonists
- Approved for horses and limited for adrenal disease in ferrets
- Not approved for use in other species in the US
- DO NOT USE IT EXTRA-LABEL - this will risk your license
37
GnRH antagonists MOA
- Blocks pituitary GnRH receptors
| - Effective shortly after administration
38
GnRH antagonist route
- Requires frequent administration
| - No depot products
39
Negative side effects of GnRH antagonists
- Adverse histamine release
40
Availability of GnRH antagonists
- Not commercially available
41
How do GnRH-toxin conjugates theoretically work?
- GnRH binds to cells in pituitary and kills those cells
42
Why don't we really use GnRH Toxin Conjugates?
- In theory they could kill other cells too
43
GnRH protein synthesis inhibitors
- Inhibitor reduces production of FSH and LH
| - variable efficacy and no available products
44
GnRH vaccines
- Stimulate antibodies to GnRH
- GnRH is a small molecule poorly recognized by the system
- No commercial vaccine available due to inconsistency in immune response
- Promising for the future?
45
Zona pellucida vaccine and oocyte/sperm vaccines?
- Not effective in males
| - Inconsistent effect in females
46
LH receptor vaccine
- Not effective in males, inconsistent in females, and injection site reactions occur
47
Active agent in zeuterin?
- Zinc gluconate and arginine
48
how does zeuterin work?
- Causes testicular degeneration and permanent sterility
49
How is Zeuterin administered?
- Intra-testicular
| - Sedation and analgesia recommended
50
Adverse reactions associated with Zeuterin
- Swelling, pain, dermatitis, infection, ulceration, bruising, etc.
51
When to perform early age surgery for spay?
- If unwanted breeding is possible
52
When should you perform ovariectomy/OVH if breeding can be prevented?
- After puberty and first estrus but before second estrus (~6 months)
53
When should you perform castration if unwanted breeding can be prevented?
After or close to musculoskeletal maturity
SA Therio
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