Cattle 2 Flashcards
What normally occurs after calving and why does metritis occur
○ Uterine fluid should be negligible 2-3 weeks after calving. - metritis - uterus does not contract properly and fluid is retained, allowing bacteria to grow.
○ Whole uterus of dairy cow should be palpable 10 days postpartum
○ Dairy cow’s uterus pre-pregnant size 40-50 days postpartum
- Lochia (uterine fluid, placental fragments, caruncles) discharged for 2 weeks postpartum
○ Normally red-brown, odourless. If it becomes stinking, uterus infected.
○ Discharge should cease by Day 30 postpartum at latest
- most bacteria are eliminated by uterine defences
Acute septic metritis (puerperal metritis) what does severity depend on, clinical signs, treatment and a major risk factor for what
- Severity of infection depends on immune system, BCS of cow, nutrition, stress, bacterial species etc …
- Clinical signs
○ Infection starts to have systemic effects
○ High temp, depressed, foul smelling redish colored uterine fluid +/- membranes
Treatment
○ Controversial - many animals don’t die!
○ RFM – if the cow is not “sick” (pyrexic) wait 5-7 days
○ Manual removal – gently – stop if blood
○ My view – pessary always; parenteral antibiotics (alamycin) if pyrexic.
§ Pessaries -> antibiotic foam
Metritis is a big risk factor for endometritis
Endometritis define, clinical signs and list some bacterial causes
- Inflammation of the endometrial lining of the uterus without systemic signs, associated with chronic postpartum infection of the uterus with pathogenic bacteria - normal 90% of cows HOWEVER if Persist beyond 3 wks – endometritis
Clinical signs
○ White discharge that DOESN’T SMELL
○ Cows are not sick
○ Causes lowered fertility if it persists
Causes
○ Arcanobacter pyogenes, Fusobacterium synergistic
○ Pseudomonas, E coli, Streptococcus,Staphylococcus,
○ clostridia - gangrenous
Endometritis how to diagnose and what is important about incidence of uterine infection after calving
○ Visually - see white pussy discharge that doesn’t smell
○ Metricheck
§ May miss some smaller cases
○ Speculum
§ Pus coming out of the vagina
○ Vaginoscopy - cervical, vaginal discharge
○ Rectal palpation - not accurate
○ Ultrasound (uterine fluid) - not common
○ Biopsy - cumbersome, deleterious result to uterus sometimes - not common
Incidence -> longer you leave uterus after calving the more likely own mechanism will get rid of infection
Endometritis list 7 risk factors
- RFMs or Metritis
- Stillbirth or calf dies within 24 hours
- Twins
- Dystocia
- Milk Fever
- Vulval discharge
- Calving induction
Endometirtis treatment and control
Treatment ○ Controversial as tends to get better with time ○ Timing is important § 2 weeks before planned start of joining -> will lead to decreased fertility Intra-uterine - metricure - cephapyrin (1st gen) Control ○ Difficult ○ Basically a nutritional problem § reduce dystocia by selective breeding § ensure clean calving environment § reduce RFM adequate feeding – esp. post partum
Pyometra pathogenesis and clinical presentation
Pathogenesis: ○ Chronic uterine infection ○ Damage to uterine wall ○ Does not produce PG ○ CL with an indefinite life span ○ No oestrus activity to remove infection presentation - Cow not sick - Uterus enlarged with doughy feel to it
Pyometra treatment and prognosis
Treatment ○ Prostaglandin to induce oestrus to get cycling then give antibiotics (intrauterine) ○ Generally an incidental finding at preg testing (empty) so don't treat as should be pregnant so just cull Prognosis ○ Unlikely to die from it ○ Often found after joining has finished ○ Treatment often not undertaken ○ More longstanding -> less fertile
Rectal examination what can palpate in what quadrants
○ Left dorsal
§ Rumen
§ Left kidney
§ Ovary
○ Left ventral:
§ Rumen
§ Uterus
○ Right dorsal
§ Left kidney
§ Lymph node
§ Small intestines
§ Cecum/spiral colon
§ Ovary
○ Right ventral
§ Uterus
§ Caecum, IntestinePalpation of ovaries rectally what can you feel and diagnosis and list the 3 main ovarian conditions
- Pea sized, no structures (anoestrus)
- Hard lump (CL)
- Soft lump (follicle)
- Big hard lump (cyst)
- Huge (neoplasm)
Ovarian conditions
1. Post-partum anoestrus (discuss later)
2. Ovarian cyst
3. Ovarian tumour
Cystic Ovarian Disease what are they, how long persist, size, why occurs and what results in
- Anovulatory structures on ovaries
- Persist for variable periods (>10d)
- Usually larger than normal follicles (>2.5cm)
- Mainly on right ovary
- Mainly Dairy Cows, less in Beef
- Lack of LH surge leads to anovulation of dominant follicle
- Infertile if cysts persist
Increases Calving interval by 50 days
What are the 3 types of ovarian cysts and how to diagnose
1) follicular cysts
2) luteal cysts
3) cystic corpus luteum
Diagnosis
1. ultrasound
2. rectal palpation
Follicular cysts what secret, size and associated with
○ secrete either oestrogenic or androgenic steroids
○ large (>2.5 cm internal diameter, with a wall less than 3 mm thick), turgid, and thin-walled,
- can be associated with either ‘nymphomaniac’ behaviour or anoestrus
Luteal cysts structure, what secret and how similar to follicular
○ have a layer of luteal tissue in the cyst wall
○ thicker walled and less prone to rupture
○ secrete progesterone - affected cows are anoestrus
○ hard to differentiate clinically (by rectal exam) from follicular cysts, but their cause and treatment is similar so determining the difference is not particularly important.
Cystic corpus luteum how significant, when form, treat and what can cause
Incidental diagnosis made when performing ultrasound or rectal exams
○ generally no changes in the oestrous cycle observed and the cows are generally fertile
○ form after ovulation when a fluid filled cavity appears in the luteal tissue
○ do not treat them
○ They feel on rectal exam like big CLs
○ Conditions of the uterus that prevent it from producing prostaglandin can cause CLs to have a prolonged lifespan, but in these cases the CL is generally normal.
What are the 3 common outcomes for a follicular cyst and result to fertility
- Persist (for up to 70 days)
○ remain dominant over others
○ growth of other follicles suppressed by E2 and inhibin. - Regress
○ replaced by normal follicle (10-50%) - Undergoes atresia and replaced by new cyst.
○ Inter-follicular interval 8.5 to 13 days
○ Regular oestrus behaviour
What are the 4 ways to treat ovarian cyst which respond well and which dont
- Manual rupture
○ relatively low recovery rate
○ risk of ovarian haemorrhages and adhesions. - GnRH intramuscularly
○ causes the release of LH and luteinisation of the cysts (not ovulation)
○ Most cows that respond come into oestrus 18 - 23 days after treatment. - Progesterone (P4)
- Follicular cysts may best be treated using a P4 releasing device to deprive the cyst of LH. This treatment will stop nymphomania behaviour immediately. In many cases, after removal, cycling continues normally. - Ovsynch program + P4 device
Most successful unless 6 months or more then don’t respond well
Ovarian neoplasms what is the main one, diagnosis and age generally occurs
Granulosa cell tumour ○ Commonest but still rare ○ Diagnosed via palpation, ultrasound ○ All ages of cattle - not just older cattle § Even pregnant cattle
What is the difference between menstrual and oestrus cycle
- Menstrual cycle – humans, chimps
- Oestrus cycle – placental mammals
○ Do not shed the endometrium (it is resorbed)
○ Start at puberty and lasts until death, with pauses during pregnancy and after calving
○ Females only sexually active during the oestrus phase of their cycle
○ “on heat” or “in oestrus”
Bovine oestrous cycle what type, pauses, cycle length and the length of 4 phases as well as oestrus
- Polyoestrus
○ Have “cycles” from puberty until death
○ Pauses:
§ during pregnancy
§ after pregnancy (post-partum anoestrus)
○ Cycle length 18-24 days
○ 4 phases
§ Oestrus ( Day 0 - in heat)
§ Metoestrus (Days 1:5 - just had a heat)
§ Dioestrus (Days 6:17 - not much happening)
§ Pro-oestrus (Days 18:21 - about to have a heat)
○ Oestrus lasts 2 hours to 2 days
What is important about bovine oestrus in terms of farm fertility, conception rates
- Much of the activity on beef and dairy farms is directed at getting cows in calf
- Cows are only fertile during Oestrus
- Conception rates 25-60%
○ Most cows need > 1 joining
What are the 3 main structures of the ovaries
1) Corpus luteum - P4
2) Follicles - oestrogen
3) Corpus albicans
Corpus luteum and follicle where do they come from, what does it do and where does it go
Where does it come from
- CL - arises from recently ovulated follicle
Foll - follicular waves - recruitment, selection, dominant
What does it do
CL - produce progesterone (P4)
Foll - grows in response to FSH/LH and produces ostreogen
Where does it go
CL - after Prostaglandin regresses to beceome corpus albicans
Foll - LH surge make ovulate morphs into CL
Brain what are the 2 important structures for reproduction what does they respond to, release and key function in oestrous cycle
- Hypothalamus
- Responds to Oestrogen
- Releases GnRH
- Key to the Oestrus Cycle:
○ Hypothalamus Response to Oestrogen
§ Negative Feedback if P4 present
§ Positive feedback if
□ P4 has been present (“progesterone primed brain”) -> post-partum - Anterior Pituitary
- Responds to GnRH
- Produces FSH and LH
○ Also produces ACTH, TSH, GH et al
Uterus what hormones produce and when
○ Prostaglandin at about d17 if not pregnant -> results in regression of the CL
○ Progesterone during pregnancy
Follicular phase of oestrous cycle what are the 2 aspects, what days and when fertile
- Follicular Phase (CL and Progesterone absent)
○ Pro-oestrus (Days 18:21 – CL regressed)
○ Oestrus ( Day 21 (and 0) - in heat)
Oestrus fertility
§ Egg is released 12 hours after end of oestrus behaviour
§ AI cows when they are seen in oestrus
Luteal phase of oestrous what present, 2 phases, what occurs within and duration
- Luteal Phase (CL and Progesterone Present)
a. Metoestrus (Days 1:5 - CL Maturing)
§ CL not responsive to PG and not as much P4 produced
b. Dioestrus (Days 6:17 – CL Mature)
§ CL just sits there producing P4 until uterus produces PG
□ What occurs in pyometra -> continued production of P4 as not PG
Follicular waves when occur and how/ what occurs
Luteal phase
§ Follicles produce Oestrogen
□ Oestrogen suppresses FSH (because P4 around)
□ Follicles need FSH
® After about 8-9 days, Follicles regress and another “wave” starts
What ends the luteal phase and what days does this occur
DAY 17-21
§ PG from the uterus -> regression of CL, decrease production of P4, oestrogen now positive feedback on hypothalamus leading to GnRH production and FSH produced -> follicular growth -> which causes oestrogen production
§ At threshold level of oestrogen, there is an LH surge and ovulation
Post-partum anoestrus what is it and what does it depend on
- Cows do not commence cycling immediately after calving
- When they do depends on:
○ Nutrient status - most important
§ Higher conception rate with increased body condition score
○ Suckling
○ Season
○ Presence of bulls
Control of the oestrus cycle what are the 4 main reasons to do this and the 4 main drugs used
Reasons: 1. Get Cows Cycling ○ “Anoestrus Cows” - was cycle and stopped ○ “NVOs” - no visible oestrus - cows that farmers have not seen cycling 2. Synchronise Cows ○ Make them cycle when we want them to ○ Batch treatment of cows ○ Reproductive and management benefits 3. Increase Fertility 4. Embryo Transfer Drugs used 1. Prostaglandins 2. Progesterone 3. Oestrogens 4. GnRH
Prostaglandin what act on, result in, given how, OHS issues and how used
- Acts on a Mature CL
- Fast Half Life
- CL regression in 24 hours
- Given by injection
- OHS issues
○ Asthmatics issues
○ Women - loss of pregnancy
Uses - If given after the first 5-7 days of the cycle, induced oestrus within 7 days of most cycling cows
○ Haven’t induced ovulation - Can also be used to induce abortion up to about day 120
Prostaglandin mechanism of action in induced ovulation and the 2 ways you can use
- Give and get drop in progesterone and may result in ovulation of a follicular wave earlier
How to do this - Cycling cows only – no effect if in post-partum anoestrus - not used in cows that are calved in less than a month
1. “Modified Why Wait”
○ 5-7 days of AI then PG
○ Easy
○ Saves a week
○ Can treat NVO (no visible oestrus)s at day 14
2. “Double PG Programme”
○ 2 shots of PG 14 days apart
§ 1 shot either more than 7 days since last oestrus - will come on in next week, will respond to second shot
§ Less than 7 days will come on the following week anyway
○ Inseminate the whole herd in a week (after second shot)
Progesterone mechanism of action for induction programs and how given
- Progesterone prime the brain
○ In post-partum anoestrus cow -> when remove get positive feedback so will result in ovulation of current follicular waves - Need long term treatment (rather than bolus)
Oestrogens how given, what animals banned in, mechanism of action in induction programs
- Usually given by injection
- Banned for use in Milking Cows
- The effect depends on Progesterone Levels
○ If P4 present, starves follicle of FSH -> Start a new follicular wave
○ After P4 drop, adds fuel to positive feedback loop of FSH and Oestrogen causing ovulation
GnRH how used in induction programs
- Uses are similar to Oestrogen
- Causes “acute secretion” of FSH and LH
- Ovulation or luteinization of the dominant follicle
- In any case, starts a new follicular wave
- Does not necessarily induce oestrus behaviour
eCG and hCG what acitivity, therefore what does it do and when used
eCG – Mostly FSH activity - Hastens follicle development - superovulation programs hCG – Mostly LH activity - Forces ovulation Superovulation programs
OvSynch program what are the 4 steps and how works
- GnRH on day 1
○ Group A - Cause ovulation in cows that have LH receptors and large follicles
○ Group B - Or increase LH levels but without ovulation as don’t have enough LH receptors - PGF2alpha 7 days later
○ Group A - regress new CL from previous GnRH injection
○ Group B - Those that didn’t have enough LH receptors should have ovulated by themselves and have CL which need to regress
○ Now should all be luteolysis - GnRH 48h later
○ Cause ovulation “sooner” - all ovulate at the same time - AI all cows 12-24 later
In the OvSynch program what is a major determinant of fertility
- GnRH 48h later
○ Cause ovulation “sooner” - all ovulate at the same time
§ Follicle state at this point is major determinant of fertility
□ Too small
® Might not ovulate
® Resultant CL might be too small to produce enough
□ Too old
® Start to regress
® Quality diminishes
As Ovsynch program relies on size of follicle for GnRH on step 3 when give this
□ Effect on follicular waves
® Wave just started (~3d)
◊ No effect, wave already up to 3 days old
® Wave underway (~4 to ~7-10):
◊ Ovulation - New wave starts 1.6-2.5 days later
® Follicle undergoing atresia (~7-10 onward)
◊ No effect –New wave starts 2-4 days later
□ On average a follicle takes 7-10 days to ovulation
Therefore ovsynch isn’t enough by itself so what are the 4 approaches to increase fertility
- Changing the timing of the FTAI
- Maximising ovulations to the first GnRH
○ Start on day 5-9 (possibly 5-12) of the cycle
○ Pre-synchrony - Fertilizing the Follicle
○ eCG at the time of the PG
§ Increases the growth of follicles
§ FSH prevents regression and keeps it young - Adding Progesterone
○ Especially in non-cycling cows- post-partum anoestrus - to get follicular waves to start
