Termination of pregnancy & contraception

Question 1

Indications for Termination of pregnancy in dogs and cats.

Answer 1

Unwanted mating:
❖ Wrong male
❖ Different breed

❖ Large difference in body size
❖ Age (too young/too old)

❖ High risk of dystocia (previous fractures, vaginal abnormalities…)

Medical indications:
▪ Pregnancy Diabetes Mellitus
▪ Pregnancy ketosis

▪ Fibroendothelial mammaehyperplasia (FEH) in cats

Question 2

Surgical technique for Termination of pregnancy in dogs and cats.

Answer 2

❖ Ovariectomy (during first part of gestation)

❖ Ovariohysterectomy (second half of gestation → risk of retention)

Question 3

Drug therapeutic technique for Termination of pregnancy in dogs and cats. (3)

Answer 3

1. Anti-progestogens: they prevent the effects of progesterone on the uterus
   initially without decreasing serum progesterone concentrations
2. Prostaglandins: Cause lysis of the Corpus luteum → induces a decrease in
   progesterone, uterine contractions and cervical dilatation.
3. Dopamine agonists: direct inhibitory effect on release of prolactin from the pituitary gland (remember prolactin is luteotropic so leads to luteolysis).

Question 4

Aglepristone (alizin®) is

Answer 4

a competitive inhibitor with a strong affinity to the progesterone receptors. It shortens
the next inter-estrus interval.

Can be used to plan and induce before C-section and induce parturition in the bitch.

Safe to use alone in early pregnancy at a dose of 10mg/kg twice 24 hours apart.

After day 45, should be used in combination with prostaglandins.

Always do ultrasound if used after day 25 of pregnancy.

Question 5

Antiprogestins, efficiency rates.
 Day 0-25:
 Day 25-45:

Answer 5

 Day 0-25: 100%
 Day 25-45: 95%

After day 45, should be used in combination with prostaglandins.

Always do ultrasound if used after day 25 of pregnancy.

Question 6

Prostaglandins for pregnancy termination.

Answer 6

Prostaglandins are Drugs that acts on the ovaries. Cause lysis of the Corpus luteum and thus induce a decrease in
progesterone, induce uterine contractions and cervical dilatation.

• Needs several injections daily
• Vomiting as side effect should be prevented with antiemetic therapy.

Prostaglandins should be used in combination with dopamine-agonist or
aglepristone.

Question 7

Dopamine agonists for pregnancy termination.

Answer 7

Dopamine-agonists are drugs that act on the pituitary gland. They stimulate the dopamine receptors which leads to a direct
inhibitory effect on release of prolactin from the pituitary gland.

They can be used in combination with prostaglandins when anti-progestins have failed and if late in pregnancy.

Cabergoline and bromocriptine both have a high affinity for dopaminergic receptors and thereby cause decreased release of
prolactin.

Question 8

Practical approach to medical abortion in the dog, early pregnancy.

Answer 8

Do vaginal smear to check whether in estrus.
Consider P4 measurement from blood.

Tx with one of these:
- surgery
- estrogens
- aglepristone (given after estrus is finished, so ask them back in a week)

Question 9

Practical approach to medical abortion in the dog, mid pregnancy.

Answer 9

First confirm pregnancy.

If pregnant, do aglepristone.
Confirm abortion in 10 days time by U/S.

If abortion is incomplete, give aglepristone with PGF2alfa.

Question 10

Practical approach to medical abortion in the dog, late pregnancy.

Answer 10

First confirm pregnancy.

If pregnant, either use a combo aglepristone and PGF2alfa or PGF2alfa with dopamine agonist (e.g. cabergoline).

Confirm abortion by U/S in 1 week.

If abortion incomplete, continue medical tx or perform OVH.

Question 11

If a bitch is mismated→ what to do?

Answer 11

Get a good history → has the bitch been mated, is she in estrus?

Next step:
❖ Vaginal smear
❖ Measuring of progesterone.

If she has been mated during the last 24 hours → do a vaginal smear→ put it in
saline for 10 min→ centrifuge→ look for spermatozoa.

Options:
1. Treat with Alizin® twice 24 hours apart after end estrus.

2. Do ultrasound day 25 after mating and if negative re-check in a week. Tx only if pregnancy confirmed.

Question 12

Practical approach to medical abortion in the cat.

Answer 12

Aglepristone(Alizin®) can be used as for the dog until day 40-45 days of pregnancy, alone or in combination with prostaglandins in mid pregnancy.

❖ The dose in cats is 15mg/kg sc BID 24 hours apart.

❖ The affinity for uterine receptors in the cat are 9 times greater than progesterone
itself, but the bioavailability is lower.

A lot is still unknown about progesterone in cats - it seems that the queen is not completely dependent on progesterone to maintain pregnancy after day 40/45.

Therefore aglepristone as an anti-progesterone drug can’t be used after day 45.

Question 13

Prostaglandins for medical abortion in the cat.

Answer 13

❖ Are better tolerated in cats than in dogs

❖ But the sensibility of the CL is low during the first month of pregnancy

❖ Is normally used in combination with aglepristone or dopamine-agonists

Question 14

Dopamine agonists for medical abortion in the cat.

Answer 14

❖ Can be used alone until day 45 of pregnancy.

❖ After that in combination therapy

Question 15

Medical contraception with progestins.

Answer 15

Mode of action:
❖ Altered motility of the reproductive tract
❖ Altered receptivity to oocyte implantation
❖ Negative feedback on hypothalamus and pituitary gland.

Produces an artificial luteal phase.
Treatment should always be started in anestrus due to risk of pyometra in diestrus.

They are available for dogs and cats, but are not recommended for animals intended for breeding.

Question 16

Contraceptive Progestin Medroxyprogesterone acetate (MA)

Use in the bitch and in the queen?

Answer 16

Bitch:
❖ 0,55 mg/kg/day orally in anestrus → postponed estrus for 3 months.

❖ 2,2 ng/kg/day for 8 days in proestrus → signs subside within days and the bitch will not ovulate in 92% of the cases, pyometra in 0,8% cases.

Queen:
❖ 2,5-5 mg/cat/day for 5 days → once weekly, start during an-or inter-estrus.

❖ 5 mg/cat/day until estrus stops → then once weekly.

Not useful for male dogs and tom cats.

Question 17

Contraceptive progestin Proligestone.

Use in the bitch and in the queen?

Answer 17

depot injection with gestagenic action (meaning relating to progestin)

Bitch:
❖ Injection in anestrus, initial dose 10-30 mg/kg sc

❖ Repeated 5 months later

❖ Next estrus will occur 3-9 month after the last injection.

❖ Up to 3% of the bitches will fail to come into heat again.

Queen:
❖ Dosage 30 mg sc → suppression for 8 months.

❖ More efficient than medroxyprogesterone acetate and less side effects.

Question 18

GnRH-agonists for contraceptive.

Answer 18

Deslorelin acetate (Suprelorin®) comes in 4,7 mg and 9,4 mg implants.

• Acts by suppressing the function of the pituitary axis when applied in a slow
  releasing dose.
• Results in the failure to synthesize and release FSH and LH → suppression of serum testosterone → suppression of sperm production and folliculogenesis → infertility.
• After implantation, there is an initial increase in FSH/LH followed by a rapid
  decrease in 9-20 days → flair up period.

Question 19

Placement and removal of the suprelorin implant.

Answer 19

 Normally the implant is placed subcutaneously in the neck region and is not removed.

BUT

 In cases where the owner want the dog to regain fertility when the implant is still
working, it can be very difficult to find the implant again in this region.

THEREFORE
 Put instead the implant subcutaneously in the umbilical region → it’s always palpable and easy to find.

Expected regained fertility after removal in 2-3 month.

Question 20

GnRh-agonists in male-dogs:

Answer 20

❖ Rapid reduction in testosterone→ decrease in libido (some males still want to mate)→ decreased spermatogenesis → induced temporary infertility → reduction in the size of testicles.

❖ Infertility is normally achieved in 4-6 weeks, but up till 12 weeks has been noted in some animals.

❖ 4,7mg implant → infertility for 6 weeks - 6 months

❖ 9,4mg implant → infertility for 8 weeks – 12 months

Minimal side effects
❖ To prevent the flair-up effect on the prostate the first weeks after implantation, use osaterone azetate (Ypozane®) orally one week before implantation.

Question 21

GnRH-agonists, off label use in the
Bitch.

Answer 21

When Implanted in anestrus:
❖ Undesirable side-effect is induction of estrus

❖ After that, a down regulation takes place and the bitch goes out of estrus for
6-12 month depending on the size of implant (4,7mg/9,4mg).

When Implanted in diestrus:
❖ No estrus induction

❖ Increased risk of canine endometrial hyperplasia – pyometra complex.

When Implanted pre-pubertal:
❖ At 4 month of age it’s very safe and no estrus induction has been noted.

Side effects : persistent estrus, induced lactation, behavioral changes

Question 22

GnRH agonist, off label use in the Queen:

Answer 22

❖ Estrus induction is registrered in 10-40% of the cases after implantation →
followed by down regulation of the gonadotropins.

❖ Suppression of estrus after implantation of 4,7 mg implant for up to 18 months (sometimes more).

❖ Pyometra has been registered after implantation, but not frequently.

❖ Can be used safely pre-pubertal because of the very variable period of effect, it´s always advisable to place the implant subcutaneously in the umbilical region to be able to remove it if necessary.

Question 23

GnRH agonist, off label use in the tomcat:

Answer 23

❖ Effect normally after 2 month

❖ Increased libido (flair-up effect) first 2 weeks after implantation.

❖ Disappearance of penile spines and atrophy of the testicles.

❖ Disappearance of urine marking

❖ Regaining of fertility in 15-25 month

Question 24

Melatonin implant in animals

Answer 24

18 mg melatonin implant (used for estrus induction in sheep (short- day breeder)

Mechanism:
→ an increase in melatonin
→ decrease in the release of GnRH
→ decrease in the release of FSH/LH
→ no stimulation of follicular growth and
spermatogenesis
→ anestrus occurs

Question 25

Melatonin implant for the cat

Answer 25

The cat is a long-day breeder
→ less than 14 hours of light
→ prolonged anestrus.

Effect of the melatonin implant in cats:
- Queen: safe, but only short term estrus suppression (2-4 months) in post-pubertal cats

• Tom: reduced semen parameters that starts to increase after 120 days

Question 26

Other contraception methods (not used for veterinary practice yet). (8)

Answer 26

 Androgens and antiandogens
 Estrogens and anti estrogens

 GnRH antagonists
 Prolactin

 GnRH vaccines
 LH and LH receptor vaccines

 Zona Pellucida immunization
 Sperm antigen immunization

Question 27

Surgical methods of contraception in dogs and cats. (3)

Answer 27

1. Removal of the gonads (spaying/neutering)
2. Vasectomy
3. Intratesticular injections

Question 28

Removal of the gonads in various species.
Bitch and queens:
Dog:
Tomcats:
Rabbit/guinea pigs

Answer 28

Bitch and queens:
❖ Ovariectomy or ovariohysterectomy (routinely linea alba, but is also done via flank incision) or laparoscopic

On young animals with no history of uterine disease, normally only the ovaries are removed.

Dog:
❖ Castration pre-scrotal with a median incision or with scrotectomy if necessary (covered testicles).

Tomcats:
❖ Castration with scrotal incision on both sides (uncovered)

Rabbit/guinea pigs
❖ Castration with scrotal incision on both sides (uncovered) but ligation must be done over the vaginal process to prevent inguinal herniation.