The Reproductive Companion Animal Flashcards
Detail the HPG axis in Females
What is Prolactin?
- A luteotrophic agent produced in the anterior pituitary
What are the roles of prolactin?
- Stimulate and maintain the CL, allowing the gestation period to be maintained
- Prepare for and maintain lactation
-Influence maternal bhvrs
Who is th emain regulator of prolactin?
DOPAMINE
What are the options for control of the female breeding cycle?
- Surgical (OVH, OV, Tube ligation)
- Intrauterine, intravaginal devices
- Chemical (Progestogens, Androgens, GnRH agonists, Melatonin)
What may influence the choice of contraception?
- Purpose
- Demographics
- Culture
- Ethnics
- Economics
- Species
What is the MOA for progestogens?
- Mode of action is unclear
May block production/ release of, or response to , GNRH - May decrease secretion of FSH and LH
- May have a direct effect at ovarian level by altering secretion of oestradiol
What are the effects of action
- Temporary postponement -> start progestogens just before pro-oestrus
- Prolonged postponement -> Start treatment during anoestrus
- Suppression of oestrus -> Start at onset of pro-proestrus
What are the different synthetic analgogues of progesterone available?
- Delmadinone acetate (not licensed in females)
- Megestrol acetate (short acting; temporary postponement)
- Proligestone (cats, dogs, ferrets)
Detail Proligestone use
- Repeat injections in anoestrus/dioestrus
- Single injection in anoestrus / dioestrus
- Single injection at onset of pro-oestrus
What GENERAL side effects with Progestogen use?
- Skin reaction at injection site
- PRegannt animals -> delays parturition / masculine foetuses
- Bhvr / metabolic changes: polyphagia, PUPD, inc BCS
- Steroid effect - adrenocortical suppression
What Side effects with PROLONGED tx with progestogens?
- Mammary enlargement
- CEH/ pyometra
- Insulin resistance - DM
- Cushings
IS fertility affected by the use fo progestogens?
Usually no - but endometrial proliferation may affect function
MOA of androgens?
- -ve feedback on HPG axis
- Androgen receptor in oestrogen target tissues may decrease the effectiveness of response to oestrogens
Androgens timing?
Given in first hald of anoestrus -> prolonged postponement
What side effects fo androgens admin?
- Low-grade vaginitis
- CLitoral enlargement
- Urine spraying
- Mounting bhvr
- Endometrial atrophy
Examples of androgen products we may use?
- Testosterone
- Milbolerone (synthetic analogue not licensed)
- Nandrolone (licensed for CRF in cats)
Name a GNrH Agonist
Deslorelin acetate
MOA of Deslorelin?
- Desensitises GnRH receptors int he pituitary
- Lh and FSH production reduced
Describe Deslorelin use
-Licensed for prepubertal female dogs only
- Implant admin between 12 and 16 wks old
- Induced temporary infertility to delay first oestrus
What happens with initial use of Deslorelin?
- Initial dose causes surge of pituitary hormone release
- May increase fertility until down-regulation occurs
What is required for the safe use of chemical control?
- Complete reproductive history - when was last oestrus?
- Complete clinical exam
- Palpation of mammary glands
- Vaginal smear to ensure not in oestrus
- Serum biochemistry to check liver function and glucose metabolism
Why may we consider preganncy termination?
- Unwanted puppies/ kittens
- Wrong dog/ tom
- Age concerns
- Hgh risk of dystocia
- Medical conditions
How do we do we terminate pregnancy
- Surgery - ovh
- Chemical: Progesterone antagonist (aglepristone), Oestrogen, PRostaglandin, Dopamine agonist (cabergoline)
What is Aglepristone (Alizin) ?
Synthetic steroid
MOA of Aglepristone?
- Competes with progesterone at receptor level
- Strong affinity for receptors in uterus
- devoid of any agonist activity - true competitor