Pharmacologic Control of Canine Repro Flashcards
1
Q
what are the 3 main options for female sterilization?
A
- ovariohysterectomy (OHE)
-increased risk of ureteral ligation
-ovarian remnants
-risk of hemorrhage
-uterine stump complication
-fistulas, granulomas
-urinary incontinence - ovariectomy (OV)
-common in rest of world (not USA)
-decreased surgery and anesthesia time
-smaller incision
-decreased abdominal trauma
-no pyometras
-low risk uterine tumors (<0.003%)
-also risk ovarian remnants - ovary sparing spay (OSS)
-no pyometra (stump pyometra potentially tho)
-risk of mammary tumors
-increased risk of pseudopregnancy
-ovarian cysts, tumors, or fibrosis
comparing relative risk of techniques:
-no difference between OHE and OV surgery times, incisions, or pain on recovery (according to most studies)
-need more long term data on OSS
2
Q
describe timing of spay/neuter
A
- around 6-9 months old for placing purebred quality animals (in shelter, now or never)
- age at gonadectomy matters for females
-decreased risk of mammary tumors if spay before 1st estrus
-no benefits for castration of males - multitude of conflicting studies on best practice based on
-ortho disease
-behavior
-obesity
-AKA: no one size fits all solution but the benefits of spaying dogs before 1st or second estrus outweigh risks at least - appropriate age is likely breed and circumstance dependent
3
Q
describe ovarian remnant syndrome
A
- recurrent estrus after OHE (or pseudopregnancy)
-piece of or whole ovary left behind
-reported as surgeon error - remnants make up 17-43% of complications, almost always due to incomplete removal of tissue
- on average show up approx 15 months post OHE (but can be 3 months to 5 years post OHE)
- present for some degree of vulvar discharge on a cyclical basis, mammary development, or being the subject of interest of male dogs
- ddx for vulvar discharge in spayed bitch:
-uterine stump pyometra
-vaginitis
-coagulopathy
-trauma
-foreign body
-exogenous estrogens
-vaginal neoplasia
4
Q
describe diagnosis of ovarian remnant syndrome
A
- vaginal cytology: esp if actively in heat or bleeding
- bloodwork: estradiol, progesterone, AMH, LH
-progesterone and AMH preferred first line testing (ideally a couple weeks post bleeding/heat event but at any point will work)
-AMH: from early antral follicle and from granulosa cells ONLY; positive AMH = you KNOW there are granulosa cells reamining in that dog
-progesterone: from corpus luteum; if present, is able to make a follicle
-estradiol produced in low levels in other body tissues and only elevated at specific times of the year (comes from early antral follicles as repro-wise); wasting client money to test unless you think was exposed to exogenous estrogens!
-LH should be baseline in an intact female and only high 2 days out of the year when peak, but is basally high in spayed females! (no negative feedback from ovaries!)
- +/- ultrasound: can be very difficult to visualize
5
Q
describe treatment of ovarian remnant syndrome
A
- surgical removal of all pedicle scar tissue and submit histology to ensure removed what you meant to remove!
-most commonly remnants are on right side of animal but check both sides!!
-literature says remnants are always at the pedicles (no ectopic tissue), but still check just in casies
- +/- hormonal therapy
6
Q
describe contraceptive use in canines
A
- for temporary prevention: show dogs, field trials, vacations, etc.
- permanent use for medical conditions with high risk of anesthetic or surgical complications
-when spaying is not an option - for wild captive canines
- knowing the stage of the cycle matters!!
-some can only be used during anestrus: progestagens, androgens, GnRH agonists
-NEVER introduce during estrus or diestrus
7
Q
describe progestagens for dogs contraception
A
- megasterol acetate: the only approved progestagen for dogs
- estrus prevention use:
-MUST start >1 week prior to proestrus
-treat for 32 days
-92% effects - estrus suppression use:
-MUST start in first 3 days of proestrus, treat for 8 days
-onset suppression in 3-8 days, 97% effective
-will return to estrus in 4-6 months - side effects:
-PYOMETRA, weight gain, lethargy
-DO NOT USE if mammary neoplasia, diabetes mellitus, liver or uterine disease
-NOT RECOMMENDED if: first estrus, or for more than 2 consecutive estrous cycles
8
Q
describe mibolerone contraceptive use for dogd
A
- the only approved androgen for dogs
- start more than 30 days prior to proestrus
-check progesterone and cytology before starting treatment to ensure in anestrus - can prevent estrus for up to 2 years
- return to estrus in 70 days after withdrawal (7 to over 260 days)
- check hepatic and renal function before initiating treatment
- side effects:
-clitoral hypertrophy
-vulvar discharge
-male behavior
-obesity
-improved hair coat - contraindications:
-estrus, pregnancy, renal or hepatic disease, prepuberty, uterine disease
9
Q
describe GnRH agonist contraceptive use for dogs
A
- leuprolide acetate: 1mg/kg
-reversible azoospermia (onset 3-8 weeks, laster 140-260 days) - suprelorin implants:
-used in zoo populations
-not approved for domestic cats/dogs, used in europe - how work:
-first, stimulate pituitary, THEN downregulate FSH and LH, resulting in decreased estradiol or testtosterone
-will cause to come into heat or increase repro behavior at first, and then decrease (so warn owners)
10
Q
what do you do first following an accidental mismate in dogs? (2)
A
- check a vaginal cytology to see if in heat and close to ovulation, check for sperm
- check progesterone to predict when would whelp if mated
11
Q
describe pregnancy termination
A
- indications:
-mis-mating
-age/health concerns
-abnormal gestation - goal: remove progesterone!!! (remove CL)
-dogs DEPEND on luteal progesterone for pregnancy maintenance
-CLs are very resistant to PGF2a (sad) - protocols:
-use bromocryptine or cabergoline to inhibit dopamine to inhibit prolactin to begin killing the CL (one shot but takes time)
-give PGF2a: need multiple shots
-give dexamethasone: unsure of the mechanism but works
-give anglepristone: block effects of progesterone on uterine receptors, can use earlier in gestation, most humane but must import from europe
12
Q
describe use of PGF2a to terminate canine pregnancy
A
- MUST have a mature, responsive CL
-25-30d gestation
-the later in gestation, the fewer doses needed for efficacy - induces luteolysis and uterine contractions
- options:
-dinoprost/lutalyse SQ TID
-clorprostenol: every 48 hours
-give until complete evacuation! - 90% of dogs abort in less than 9 days
- must monitor fetal heart beats and progesterone to ensure complete evacuation
-progesterone must bc <2ng/ml for more than 2 days to ensure complete termination - recommend hospitalization due to side effects
-can be severe: vomiting, diarrhea, trembling, panting, tachycardia, rarely circulatory collapse
-effects are dose dependent and seen within 5 min of drug admin, last up to 1 hour
-shortens inter-estrus interval by approx 70 days
-legal to use but not an approved method in the US
-can shorten the amount of drug you need to use if you combine with a dopamine agonist
13
Q
describe dexamethasone use to terminate a canine pregnancy
A
- start after 35d of gestation
-will not work before - abortion in 7-15 days in 97% of dogs
- side effects: PU/PD (ensure not also on NSAIDs for other side effects!)
-giving a pretty high dose but not quite immunosuppressive level - unknown MOA
14
Q
how do you monitor passing of fetuses?
A
radiographs
15
Q
describe use of dopamine agonists for termination of canine pregnancy
A
- bromocriptine or cabergoline (fewer side effects)
- start after 30d of gestation, will abort in 4-7 days
- suppress prolactin secretion and cause premature luteolysis
- side effects: V/D, anorexia
- not approved in US, usually use in combination with PGF2a
