Intro/overview Flashcards
Common methods of oestrus control in small animals
- progestogen
– Proligestone (Delvosteron) - GnRH supreragonist
– Deslorelin (Suprelorin) - Human medicine (Norethisterone)
Progestogen for oestrus control
- temporary prevention
- single dose injected in anoestrus or proestrus
- long term prevention: additional doses given at 3, then 4, then every 5 months
GnRH superagonist for oestrus control
- temporary infertility in sexually immature female dogs (licensed)
- temporarily infertility in sexually mature female dogs (not licensed but good data)
- implant placed and can be repeated every 6-12m dependent on BW and size of implant
Human medicine for oestrus control
- progestogen that is weakly androgenic
- some anabolic effect -> use in greyhounds, has positive effect on muscle building as well
- no licence
- tablets given daily
Bitch cyclicity
- mon-estrus (interval 7m)
- spontaneous ovulator
- obligatory long luteal phase similar to pregnancy (70d)
- non-seasonal anoestrus (i.e. not related to photoperiod)
Correct order of metoestrus, oestrus, anoestrus, pro-oestrus
- anoestrus -> pro-oestrus -> oestrus -> metoestrus (also called diestrus) -> anoestrus
What is unique to dogs re rise in progesterone?
- rise in progesterone before luteinisation and ovulation
– this is the development of luteal cells inside follicle wall prior to ovulation
What is the dogs mechanism for supporting the CL? What else does this hormone do?
- prolactin
- it is produced in both the pregnant and non-pregnant bitch
- it increases progesterone and is luteotrophic
- it also affects lactation and nesting/nursing behaviour
– the non-pregnant dog will display pseudopregnancy signs due to prolactin
Queen cyclicity
- seasonal (long day breeder = doesn’t cycle over winter)
– but inside cats may have disturbed photoperiodic effect and so may cycle over winter - polyoestrus
- induced ovulatory (no luteal phase unless ovulation)
– mating must occur to cause ovulation
-> Mating causes LH release - magnitude depends on different aspects - frequency of mating - high LH surge causes ovulation, low doesn’t - there’s a threshold
– no ovulation = no luteal phase = no high progesterone as this only comes from progesterone -> no CL - cycles may be 2-3w apart
– not the same as 21d cycle as no ovulation and no luteal phase
But do some queens ovulate without mating?
- yes
Are ovulated oocytes in the dog immature?
- yes, but they survive for a long period unlike other species
How to optimise breeding timing in dogs
- measure hormone changes
– repeated sampling for progesterone on d7 and looking for an increase - indirect assessment of hormones
– vaginal cytology looking mating from 80% anuclear cells
– vaginoscopy looking for mating from angulated phase
– behaviour looking for mating from 4d after onset standing oestrus (unreliable)
– vulval swelling looking for mating from onset of distinct softening (unreliable) - detect ovulation
– e.g. US, but very difficult
How to optimise breeding timing in cats
- ensure breeding occurs on the correct day (d3)
- ensure that multiple breeding are allowed within a short period of time
- possibly could consider inducing ovulation using hCG or GnRH (this requires the queen to be in oestrus so often these are given at the time of mating or immediately after mating)
Methods to investigate the repro tract
- BSE
- investigation of infertility or dz
- diagnosis/evaluation of pregnancy
- investigation of dystocia
- investigation of postpartum dz, e.g. RFM
US can be used for all
Also:
- clinical history
- previous breeding records
- venereal pathogen screnning
- general CE
- specific repro exam
Clinical history - what q’s to ask
- previous cycles (normal/abnormal?)
- normal mating?
- ovulation confirmed?
- previous pregnancy confirmed?
- pregnancy to term?
- repro tract discharge?
- behavioural manifestations?
Bitch venereal pathogen screening - bacteriology
Vestibule and vagina have normal commensal flora that changes daily
– many bacteria present, e.g. Staphs, Streps, E. coli
– often mixed flora
– Pseudomonas is not commonly isolated
– Brucella canis is a venereal pathogen in some countries and has now been identified in the UK
-> can cause abortion, stillbirth, fading pups
-> is zoonotic but with a low chance of transmission to man
The uterus is normally bacteriologically sterile
– vaginal bacteria may enter the uterus at oestrus
Is vulval discharge normal in dogs?
- during pro-oestrus/oestrus
- common during pregnancy
- often mucoid or lightly purulent
Interpreting vaginal swabs from the bitch
- most swabs taken from vestibule
- swabs should be expected to contain commensal bacteria
- the only known bacterial venereal pathogen is Brucella canis
- routine screening of the clinically normal bitch is pointless (may change if Brucella becomes more prevalent)
- routine AB use is not appropriate
Bitch venereal pathogen screening - virology
- canine herpes virus
– venereal pathogen causing vesicular lesions in the genital tract of dogs & bitches
– can cause resorption, abortion, stillbirths (depending on when infection occurs)
– infection can be venereally or via resp tract
– some viral recrudescence occurs
– vaccine is available (Eurican Herpes) for bitches and is given 2x during pregnancy to protect the litter - other viral infections during pregnancy can cause pregnancy loss but are not venereal pathogens:
– canine parvovirus
– canine adenovirus
– canine distemper virus
– usually as the animal becomes ill/feverish, not because the virus is toxic to foetus
Queen venereal pathogen screening - bacteriology
Vestibule and vagina have normal commensal flora that changes daily
– many bacteria present, e.g. Staphs, Streps, E. coli
– often mixed flora
– bacteria commonly isolated from stillborn kittens are likely opportunistic commensals
The uterus is normally bacteriologically sterile
– vaginal bacteria may enter the uterus at oestrus
Queen venereal pathogen screening - virology
Feline leukaemia virus (FeLV):
- implicated in infertility, resorption and abortion
- most common cause of infectious infertility
- screening of queens prior to breeding is important
Other viruses that cause pregnancy loss associated with infection during pregnancy, but are not venereal pathogens:
- Feline herpes virus
– uncommon
– late abortion
– vaccination effective in prevention
- Feline panleukopaenia virus
– uncommon
– abortion, stillbirth, cerebellar hypoplasia
Investigating breeding soundness, infertility & repro tract abnormalities - general clinical exam
- looking for maturity, adult body size, systemic disease
- ruling out hereditary disease
- consider specific schemes / DNA tests (kennel club)
- consider suitability for breeding based on temperamental assessment
Investigating breeding soundness, infertility & repro tract abnormalities - perineum and vulva
Normality or abnormality?
- presence of discharge
– normal in oestrus
– normal muco-purulent discharge in early pregnancy
- assess clitoris and vestibule
Assess stage of oestrus cycle
Investigating breeding soundness, infertility & repro tract abnormalities - mammary glands
- Normal or abnormal?
- Stage of oestrus cycle
– mammary enlargement under influence of progesterone
Investigating breeding soundness, infertility & repro tract abnormalities - digital examination of the vagina
- vaginal abnormalities are common
– narrowing
– dorso-ventral bands
– hyperplasia - ^ best detected by palpation
– can evaluate degree of narrowing and extent
Investigating breeding soundness, infertility & repro tract abnormalities - vaginal endoscopy
- assessment of stage of cycle
- document of normality or abnormality
- during oestrus can be performed in standing, non-sedated bitch
Vaginal endoscopy - assessment of time to breed - Phase O, S, A1, A2, A3, D1, D2
Phase O
= oedematous, moist
- low-levels of progesterone (0.5-1.5ng/ml)
- ovulation: unknown time
Phase S
= shrinkage on surface of mucosa as progesterone concentration increases
- progesterone (2.5ng/ml)
- ovulation soon (i.e. ~2 days away)
- day of LH surge
Phase A1
= shrinkage (even less oedematous) and wrinkling more prominent
- progesterone high (7ng/ml)
- ovulation
Phase A2
= beginning of fertilisation period
- progesterone high (10ng/ml)
- ovulation ~2d ago
- mucosa very angled
- start breeding from 1st detection of this stage
Phase A3
= middle of fertilisation period
- progesterone high (15ng/ml)
- ovulation ~4d ago
- becoming more oedematous/less angled
Phase D1
= end of fertilisation period
- progesterone high (30ng/ml)
- ovulation ~6d ago
- becoming more oedematous/less angled
Phase D2
= luteal phase
- progesterone high (50ng/ml)
- ovulation ~10d ago
Use of vaginal cytology
- assessment of stage of cycle
- establishment of normality
– collection by aspiration/swab
– haematology stains
-> look for large anuclear cells
Uterine US
- uterus is positioned dorsal to the bladder
– tubular in sagittal plane
– circular in transverse plane - appearance varies according to stage of oestrus cycle
Common uterine pathology
- cystic endometrial hyperplasia (CEH)
- mucometra
- pyometra complex
When can you diagnose a pregnancy in the bitch/queen?
- as early as d20 after ovulation in the bitch
– but normally sea undertaken 28d from mating as day of ovulation not always known - as early as d18 after ovulation in the queen
– but normally scan undertaken 28d from mating
Difficulty with examining ovaries by US
- appearance varies according to stage of cycle
- can be difficult to detect as bursa often contains much fat
- ovulation difficult to determine as CLs have fluid cavities
Most common ovarian abnormality where imaging used to investigate
- ovarian neoplasia
Use of radiography
- usually used to determine pregnancy or foetal number/death
- less commonly used to examine the reproductive tract (use US instead)
- plain radiographs
- contrast studies
When does mineralisation of the skeleton occur?
- day 45
How do you count foetal number from radiographs?
- count skulls
How and when to detect foetal death on radiographs
- several days after death
– loss of normal posture
– overlapping of skull bones
– accumulation of gas in foetus/uterus
Plain radiography
- normal ovaries and uterus not normally visible on plain radiographs
- detection of enlargement may be possible in some cases, usually this is a soft tissue opacity mass causing displacement of other structures where location is suspicious of the repro tract
When does progesterone rise re ovulation?
- before and throughout
When does progesterone decline re parturition?
- before
What can the hCG stimulation test confirm?
- functioning (presence) of an ovary
What can the GnRH stimulation test confirm?
- functioning (presence) of an ovary and pituitary
How can you confirm the presence of ovaries in cats?
- in oestrus cat by induction of ovulation
– hCG stim test
– GnRH stim test - both will induce ovulation so that elevation of progesterone can then be detected
Commonest cause of infertility in the bitch
- mating at incorrect time
Commonest cause of infertility in the queen
- mating insufficient number of times on the correct day
