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
DOse of Aglespristone? - Bitch
give 2 doses 24hrs apart from day 1 to day 45 after mating
Dose of Aglepristone - Queen?
Give 2 doses 24 hrs apart; early after mating gives better results - off license for queens
When should we give aglepristone?
Dioestrus - vaginal cytology to check not too early
Describe Oestrogens?
- Oestradiol benoate (Mesalin)
- No longer licensed - aglepristone safer and more effective
MOA of OEstrogens?
- Changes biochemical environment
- Affects transit time of zygote in oviduct
- Has direct embryotoxic effects
When should we use Oestradiol ?
- Early preganncy - 3 and 5 days post mating
What side effects of Oestradiol use?
BM suppression, CEH, pyometra
Dexamethasone use?
from 0 days onwards but not recommended
Prostaglandin (Dinoprost) MOA?
- Lyse CL
- Cut -> dog CL resistant to effects of Protaglandin
- Cause uterine contractions
Side effects with Dinoprost?
serious - don’t use if known cardiac or resp dx
Other considerations of Prostagladin ?
- Not licensed for this use in the UK in dogs and cats
- PGF2 alpha sometimes used for medical management of pyometra in combination with other drugs
What is Cabergoline (Galastop)?
Dopamine agonist
MOA of Cabergoline?
- Inhibit prolactin production
- Prolactin essential to maintain CL function from mid-pregnancy onwards
- Results in luteolysis and TERMINATION
What side effects of Cabergoline use?
Transient hypotension
What is cabergoline usually used with?
PRostaglandins
DRAW OUT DECISION TREE FOR TERMINATION
What is another name for Pseudopreganncy/ false pregnancy
Pseudocyesis
When would we see a pseudopregnancy
6-14 weeks after oestrus
Cause of pseudopregnancy
Excessively elevated prolactin levels or inc response to normal levels
Signs of pseudopregnancy
- Mammary development
- NEsting/ toy fixation
- Aggression or lethargy
- Milky vulval discharge
Treatment for pseudopregnancy
- Try conservative -> inc exercise, disrupt nesting , distract from toys, prevent mammary stimulation, dec food
- Cabergoline - dopaine agonist
- Likely to be recurrent
Why do we want to avoid spaying at time of elevated prolactin?
May result in prolonged pseudopregnancy
Considerations for husbandry esp nutrition in pregnant bitch / queen?
Dogs -> inc feed in last trimester (usually fed puppy food)
Cats -> Linear increase of feed from the start of the pregnancy
Reasons for loss of pregnancy?
- Foetal abnormalities
- Premature parturition
- Hypoluteoidism
- Infection (Herpes virus, brucella)
- Gestational diabetes
- Preg toxaemia
- Toxins/ drugs
- Environment/ stress factors
Lethal causes of loss of pregnancy?
- Congenital abnormalities
- Placental insufficiency
- Uterine infection
Detail the induction of parturition?
- Not common in CAs
- Drugs no licensed
- May be used therapeutically (maternal morbidity, risk of dystocia)
Parturition should not be induced before …. days of gestation (0= day of ovulation)
60 days
What can we use to induce ?
- Aglepristone, oxytocin
- Aglepristone, PGF2a
- Nitoglycerine, oxytocin
Detail the HPG MAle axis
How can we control the male breeding cycle?
- Surgical (Castrate, Vasectomy)
- Chemical (GnRH agonist, Progestogens, Andorgens, Prolactin, Immunisation)
- Miscellaneous (Injection, US)
Describe Desloreliin use in males
- GnRH agonist - slow release long acting implant
- Causes initial 14-day testosterone surge, then testosterone levels fall
Timing of action in males for deslorelin?
- Infertility acheived from 6-8 wks after implantation and lasts 6-12 mths (different sizes) -> lasts longer in dogs <10kg, return to normal testosterone levels post-implant is variable, up to 2 years
What can superlorin also be used for ?
- Inducing infertility in ferrets - male and female
- Tx of ovarian cysts in GPs
- Oestrogen induced mammary carcinomas in rats
- Egg laying disorders (egg binding) in birds
- Bitches to delay onset of oestrus
What synthetic analogues of progestogens available (males)
- Delmadinone acetate
- Megestrol acetate (no longer available)
- Proligestone (NOT LICENSED)
Detail Delmadinone acetate use?
Does not result in infertility
- Licensed to treat hypersexuality, prostatic hyperplasia etc
Androgen use in Males?
- Testosterone
- Produces reduction in spermatozoa and motility
- Not licensed for use for control of breeding in males
- Side effects - prostatic hypertrophy
Prolactin in Females?
- Reduces fertility - reduced motility, N° and altered structure of spermatozoa
- Serum concentrations of test, FSH & LH do not alter
- Possibly a direct effect on testes rather than HPG axis
- Nothing licensed
What are the targets for immunosterilisation?
GnRH,LH and sperm antigens
Problem of immunosterilisation?
- GnRH/ LH not naturally immunogenic
- Production and duration of antibodies in unpredictable
Injection - males?
- Intratesticular, intra-epididymal, intra-vas deferens
injections - Adjuvant agent (BCG)
- Reproductive toxins (dexamethasone)
- Zinc gluconate
- Occlusive silicone (vas deferens)
- Varying degrees of reduction/duration of infertility
Ultrasound - males?
- High intensity focused ultrasound beam
- Short bursts (10 -15 mins) delivered 1-3 times at
intervals of 2 – 7 days - Suppressed spermatogenesis without affecting
testosterone levels
