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Y4 Farm Reproduction > Dystocia > Flashcards

Dystocia Flashcards

(75 cards)

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1
Q

What does dystocia mean?

A
  • difficulty giving birth
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2
Q

What % of calvings are affected by dystocia?

A

8-10%

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3
Q

Causes of dystocia

A

At conception or early gestation
- foetal sex
- foetal abnormalities
- twins
- sire factors (e.g. breed, calving ease)
- dam factors (e.g. parity, calving history)

At late gestation
- gestation length
- foetal oversize
- dam undersize
- hypocalcaemia
- peri-parturient stress

At parturition
- foeti-maternal disproportion
- uterine torsion
- foetal malpresentation
- uterine inertia
- cervical or vulval stenosis

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4
Q

Most common causes of dystocia

A

Cattle = foeto-maternal disproportion
▪ 50-80%

Sheep = malpresentations
▪ > 50% of cases

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5
Q

Effects of dystocia

A

▪Reduced welfare
▪Reduced production
– Cow = subsequent lactation
– Calf = 1st lactation
▪ Stillbirth
▪Dam death
▪Postpartum problems ▪E.g. RFM, metritis, injuries

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6
Q

Options for management of dystocia

A

▪Manual correction and deliver per vaginum ▪Caesarean section
▪Foetotomy (foetus needs to be dead)
▪Euthanasia of dam +/- foetus

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7
Q

Manual correction and delivery

A

▪ Will only be successful if foeto-maternal disproportion NOT present
– Malpresentations
– Some soft tissue obstructions (e.g. vulval stenosis)
▪ Correct malpresentation
– Epidural can be helpful (if soft tissue obstructions)
– Consider episiotomy

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8
Q

Indications for c-section

A

▪ foeto-maternal disproportion
▪malpresentations that cannot be corrected
▪breech calves
▪elective (e.g. high value calves) (ethical q’s re breeding animals knowing they’ll need a c-section, e.g. Belgian blues)

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9
Q

When are c-sections not suitable?

A
  • if calf decomposing→foetotomy
    – would contaminate the dams abdomen with bacteria -> very likely to get peritonitis
  • Alternative approach needed if C-sec performed
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10
Q

Foetotomy (AKA ‘embryotomy’)

A

▪Foetus will not survive – only suitable if already dead (preferable to C-sec if not fresh) or if euthanasia of foetus required
– but euthanasia of the foetus is very tricky, esp without contamination/damage of the dam as well
▪Epidural recommended→provides analgesia and reduces straining
▪Partial or total
– Partial = removal of part of the foetus only (e.g. head)
– Total = division of the whole foetus into two or more sections
▪ Fetotome prevents soft tissue damage to the dam with the wire

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11
Q

Advantages of foetotomy

A
  • Reduction in foetal size allows easier delivery
  • Can be quick (especially partial)
  • Can be done without assistance (although assistance recommended if possible)
  • Avoids C-sec
    – Especially useful if C-sec contraindicated
    (emphysematous foetus)
    – Better for dam in some circumstances
  • Can be performed with minimal equipment if required
    – Especially sheep
    – Partial and subcutaneous need less equipment
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12
Q

Disadvantages of foetotomy

A
  • Risk of iatrogenic injury
    – Can be severe or even life-threatening
  • Can take a long time (especially total)
    – Exhaustion of dam and vet
  • Requires training and technical competency
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13
Q

Percutaneous foetotomy

A
  • Percutaneous = dissection is made through foetal skin
  • ‘classic’ technique
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14
Q

Subcutaneous foetotomy

A

= limb removal without skin
- An incision made in the skin
- Foetotomy knife introduced under the skin and limb dissected away from body
- Easier, less tiring and less equipment needed

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15
Q

Indications for percutaneous foetotomy

A
  • Foeto-maternal disproportion
  • Pathological foetal oversize
  • Congenital foetal malformations
  • Malpresentations that cannot be corrected

NB: these all only apply where the foetus is already dead

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16
Q

Indications for subcutaneous foetotomy

A
  • Same as for percutaneous except correction must be achievable through limb removal only
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17
Q

Less common causes of dystocia

A
  • Dropsical conditions (placental origin)
  • Congenital abnormalities (foetal origin)
  • Teratogens
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18
Q

What does ‘dropsy’ mean?

A

= accumulation of fluid

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19
Q

What are the 2 dropsical conditions?

A
  • hydrallantois
  • hydramnion
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20
Q

What is hydrallantois?

A

▪ Excess fluid accumulation in the allantois
▪ 85-90% of bovine cases
▪ Placental origin
▪ Foetus normal
▪Sporadic occurrence
▪Up to 10x expected volume of allantoic fluid
– Normal = 8-15 L
▪Fluid accumulates after mid-gestation
▪ Failure in mechanisms of production and absorption
– Excessive production, little-to-no absorption
▪Reduced number of placentomes
▪ Permanent alteration of endometrium

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21
Q

What is hydramnion?

A

▪ Excess fluid accumulation in the amnion
▪ ~10% of bovine cases
▪ Foetal origin
▪ Foetal abnormalities present
▪Related to foetal abnormalities
– Failure of swallowing or digestion of foetal fluids
– Future breeding prognosis of dam is reasonable
▪Progressive abdominal enlargement in 3rd trimester
– Slower development than hydrallantois
– Uterus and abdomen accommodates extra fluid better
– Less sick cow
– Placentomes still palpable
▪May go undiagnosed until parturition
– Large volume of thick, syrupy fluid
– Foetal abnormalities

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22
Q

Can hydrallantois and hydramnion occur together?

A
  • yes occasionally
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23
Q

Hydrallantois prognosis

A
  • guarded to poor
  • if survives, cull of cow recommended
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24
Q

Hydrallantois CS

A

▪Bilateral abdominal distention
– Symmetrical
▪Uncomfortable
▪ Inappetant
▪Reduced/absent rumen function
– Due to compression
▪Recumbency
▪Tight uterine wall palpable per rectum
– Could potentially rupture from rectal

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25
Tx of dropsical conditions
▪ Induce/terminate pregnancy -- Prostaglandin / steroids -- Need to provide replacement fluids to cow -> Prevent hypovolaemia -> Correct electrolyte disturbances ▪ Euthanasia -- Salvage slaughter if fit to travel ▪ Trochar and drain fluid -- Pass trochar into cervix -- Useful if very close to calving, otherwise would have to repeat frequently -- Rapidly re-accumulation of fluid occurs in hydrallantois -- Need to provide replacement fluids to cow? -> ongoing debate re whether need to replace fluids -> risk of hypovolaemic shock BUT it's extra fluid that shouldn't be there, so removal may not be an issue -> IV fluids unlikely to cause harm
26
Congenital abnormalities
- arthrogryposis - schistous réflexes - congenital chondrodysplasia - hydrocephalus - large offspring syndrome - cranial defects
27
Arthrogryposis
▪ Relatively common malformation ▪ Limb ankylosis (fusion of the joints in unusual directions) ▪ Usually combined with other congenital malformations (e.g. cleft palate) ▪ Liveborn neonates unable to stand → euthanasia ▪ Foetotomy or C-sec usually needed
28
Causes of arthrogryposis
Genetic - Autosomasal recessive in Charolais breed -> Arthrogryposis, cleft palate, scoliosis (spinal twist), kyphosis (spinal rounding) Viral infection in utero - *Schmallenberg* virus -> Arthrogryposis affecting multiple neonates in same year ->Sheep, goats and cattle all affected. - Bluetongue virus -> Ruminants and camelids affected. ->Abortion is more common. - Akabane virus -> Not reported in UK - Viruses are the most common cause, esp if multiple animals affected Teratogenic plants - Lupines (not all species) -> Contain anagyrine. -> Congenital deformities occur in cattle if ingested between d 40 and 70 of gestation -> USA.
29
Schistosomus reflexus
▪‘Inside out’ foetuses ▪Rare, fatal malformation -- Likely genetic ▪Foetotomy or C-sec ▪Be careful not to confuse with uterine rupture ▪ Good CE and vaginal exam will differentiate between this and uterine rupture
30
Congenital chondrodysplasia
▪‘Bulldog’ calves -- Short legs -- Domed head -- Brachygnathia inferior (undershot jaw) ▪Dexters, Holstein, Jerseys -- Likely genetic -- Other breeds reported ▪Does not always = dystocia
31
Hydrocephalus
▪ Increase in CSF volume → domed head ▪ Calves born alive may have neuro deficits ▪ Teratogenic viruses implicated -- BVDv -- BTV -- Akabane virus (not UK) ▪ May also form part of mixed congenital disorders ▪ Mild cases may calve unassisted ▪ Severe cases = C-sec or partial foetotomy (remove head)
32
Large offspring syndrome
▪ Also termed ‘abnormal offspring syndrome’ -- Varied congenital abnormalities reported ▪ Associated with assisted reproductive technologies -- Embryo transfer -- In vitro techniques -- Cloning ▪ Exact mechanisms unclear ▪ Very large neonates -- May be 2x average size -- Dystocia -- Macroglossia (enlarged tongue) -> can affect ability to suckle and feed
33
Cranial defects
- Ancephaly - Otocephaly - Bicephaly
34
What is ancephaly?
- no head
35
What is otocephaly?
- some head structures present but no skull
36
What is bicephaly?
- 2 heads
37
What is a teratogen?
- agents causing foetal abnormalities or death
38
How does the timing of exposure to teratogens influence the outcome?
▪Zygote→affected by chromosomal or genetic abnormalities. Often result in embryonic death ▪Embryo→affected by environmental and infectious agents. Most high risk period for developing abnormalities ▪Foetus→more resistant to environmental teratogens but structures that develop late are still susceptible to being affected (e.g. palate)
39
Effects of BVD virus on calves
* Abnormalities of the brain, eyes and neurological development * Foetal death * PI calves -- May be small but may appear normal -- Increased susceptibility to disease -- May develop mucosal disease
40
Common viral teratogens (& who they affect)
- BVD virus - Border disease virus - Schmallenberg virus - Bluetongue virus - Akabane and Aino viruses
41
Effects of border disease virus on lambs & kids
* Abnormalities of skin, skeleton and neurological system -- ‘hairy little shakers’ * Foetal death * PI lambs -- Similar to PI calves
42
Effects of Schmallenberg virus
* Arthrogryposis * Foetal death
43
Effects of bluetongue virus
* Arthrogryposis and other deformities * Foetal death and abortion (more common than malformations)
44
Effects of Akabane and Aino viruses
* Congenital malformations * Not currently in UK * Midge spread→may be seen in future
45
Examples of environmental teratogens
- Hemlock - Nitrates/nitrites (nitrate accumulating plants e.g. sugar beet, alfalfa) (nitrite based fertilisers) - Ergotism (mouldy feed) - Lead
46
Effects of hemlock
* Skeletal abnormalities if ingested between days 40-70 of gestation * Abortion * NB. is highly toxic to cattle and often causes death of dam
47
Effects of nitrates/nitrites
* Excess nitrate consumption exceeds rumen capacity for metabolism → nitrate and nitrite absorbed into circulation → interacts with haemoglobin → oxidation to methaemoglobin * This process can also occur in the placenta → foetal death, weak calves
48
Effects of ergotism
* reduced size offspring
49
Effects of lead
* Concentrates in CNS of foetus -- Neurological defects -- Reduced foetal size * Also causes problems in the dam
50
Examples of pharmacological teratogens
- Benzimidazoles - Tetracyclines - Steroids - Prostaglandins - Xylazine
51
Effects of benzimidazoles on sheep
- Abnormalities of the foetal skeleton, kidneys and vascular system
52
Effects of tetracyclines on all ruminants
- Dental discolouration
53
Effects of steroids on all ruminants
- Abortifacient
54
Effects of prostaglandins on all ruminants
- Abortifacient
55
Effects of xylazine on all ruminants
- Abortifacient in later stages of pregnancy - Causes uterine contraction -> abortion - Detomidine also has similar, but less pronounced effects
56
What is puberty in cattle driven by?
- weight, not age - puberty occurs at ~2/3 of adult BW
57
Early unwanted pregnancy in heifers
▪Well grown heifers unexpectedly conceive to mis- mating -- Uncastrated youngstock -- Bulls running with herd -- Entire males escaping Can lead to: ▪Poor heifer growth ▪Increased risk of dystocia
58
How can an early pregnancy in a heifer be managed?
- Wait & see - Elective c-section - Induce parturition - Terminate pregnancy
59
How can an early pregnancy in a heifer be managed - wait & see
* C-sec likely needed→can be less optimal outcomes if performed in emergency * Can be effective if farmer aware of mis-mating and requests vet assistance as soon as parturition starts * Only addresses issue of dystocia
60
How can an early pregnancy in a heifer be managed - elective c-section
* Performed at/near end of gestation before parturition starts * Need a idea of gestation duration → scan * Only addresses dystocia * Justified in this case
61
How can an early pregnancy in a heifer be managed - inducing parturition
* Aim to induce near/at term for viable but small foetus * May still need C-sec if calf big * Requires reliable insemination date → scan * Only addresses dystocia
62
How can an early pregnancy in a heifer be managed - terminating pregnancy
* Prostaglandin * Glucocorticoid steroids (dexamethasone) * Reliability dependent on stage in gestation → scan * Early termination can mean limited effects of pregnancy on dam
63
Pregnancy termination using prostaglandins
▪Lysis of CL→pregnancy loss -- Progesterone needed to maintain pregnancy ▪ Abortion occurs within 7days if given <100 days gestation -- >100 days gestation timing and reliability of abortion reduced
64
Why is the stage of gestation an important factor when considering the use of prostaglandins for pregnancy termination?
- <100 days gestation = maximal chances (> 90%) - 101-150 days gestation = moderate chances (~ 60%) - >150 days gestation = lower chances (≤ 40%) -- Because placenta also a source of progesterone between days 150-200 - >270 days gestation to induce parturition → live calf
65
Pregnancy termination using glucocorticoid steroids
▪Reduces placental secretion of progesterone→ pregnancy loss -- Most effective in last month of gestation -- Can also be used after day 270 to induce parturition → live calf ▪Dexamethasone -- Give 20-30mg (for most products this is 10-15ml)
66
What can you give for pregnancy termination for mid-late gestation (i.e. >150d) or if uncertain?
- both dexamethasone AND prostaglandin - both drugs associated with increased likelihood of retained foetal membranes - no other adverse effects for the heifers reported
67
Pregnancy induction - drug choices
- Short acting (corticosteroids) -- 20-30mg dexamethasone - Prostaglandins - Prostaglandin + corticosteroid combination - Longer acting corticosteroids -- dexamethasone trimethyl acetate)
68
Short acting corticosteroids to induce parturition - advantages
* High efficacy (80-90%) when given within 2 weeks of expected calving date * Calving occurs within 72hrs of injection
69
Short acting corticosteroids to induce parturition - disadvantages
* High incidence of retained foetal membranes (RFM)
70
Prostaglandins to induce parturition - advantages
* Calving occurs 24-72 (average 45) hours after injection * Give within 2 weeks of calving date
71
Prostaglandins to induce parturition - disadvantages
* High incidence of RFM * Failure of induction common if given > 2weeks before end of gestation
72
Prostaglandin + corticosteroid to induce parturition - advantages
* More reliable than steroids or PGF alone -- Especially if dates uncertain * Calving occurs 24-48hrs after treatment
73
Prostaglandin + corticosteroid to induce parturition - disadvantages
* Retained foetal membranes commonly occur
74
Longer acting corticosteroids to induce parturition - advantages
* Used if timing of calving more important than calf viability * Given 1 month before expected calving date * Calving occurs 4-26 days after injection * Lower incidence of RFM
75
Longer acting corticosteroids to induce parturition - disadvantages
* Higher incidence of calf death (up to 45%) * Dexamethasone trimethyl acetate currently not licensed in UK

Y4 Farm Reproduction (11 decks)

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