Ovine Reproduction Flashcards
When are caesarean sections indicated in sheep?
- Non-dilation of the cervix (ringwomb)
- Foetal oversize
- Irreversible malpresentation
- Deformities
What anaesthesia is used for caesareans in sheep?
Flank infiltration, L block or paravertebral preferred
How are caesarean sections in sheep different to those in cattle?
Surgical technique similar to cattle – except always drape sheep due to wool contamination
How is a left paralumbar laparotomy in sheep approached?
- Restrain in right lateral recumbency
- No need for uterine relaxants
- Skin incision is made midway between the last rib and the stifle – over the most domed past of the flank
What method of castration is used for sheep and goats under 2 months and over 2 months of age?
Under 2 months - torsion and traction, emasculators
Over 2 months - ligation and emasculators
What does fat lamb production depend on?
- Maximise ewe conception rate
- Minimise embryonic and foetal losses
- Maximise neonatal lamb survival
- Maximise rate of growth of lambs
- Minimise losses from other causes
What are the factors affecting ewe conception rate?
- Nutrition of ewe
- Early feeding which determines early growth and adult body size
- Condition score at tupping
- Plane of nutrition prior to tupping period
- Trace element status
- Age and genotype of ewe
- Disease
What is ram fertility influenced by?
- Nutrition and body condition score
- Age and genotype
- Disease
- Ewe to ram ratio
- Season and out of season breeding for early lamb crop
- Weather
- Stress
What are the possible causes of whole ram groups being infertile?
- Balanoprosthitis causing vulvovaginitis after contact with ewe
- Epididymitis and orchitis
- Orf
- Scrotal mange – may increase temperature of the scrotum
How can you treated scrotal mange in rams?
Systemic endectocides do not work, need to use Ops topically
How does the ewe to ram ration change?
1:25 for ram lambs
1:40 for mature lambs
1:10 for synchronised ewes
What are the immediate actions to be taken for a flock where all new lambs are dead and born 3 weeks early?
- Isolate ewes that have aborted, have vaginal discharge and/or very sick/weak lambs
- Mark these ewes
- Retain for the vet any foetal membranes, dead foetuses or dead lambs
- Examine foetal membranes – cotyledons, intercotyledonary space
What are the characteristics of a campylobacter foetus on post mortem examination?
Liver lesions
Enlarged abomasum
What is investigated if there are no foetal membranes?
Paired serology from ewes:
- ELISA for chlamydia
- LAT/latent agglutination test for toxoplasma gondii
What do clinical signs of ewes in the flock indicate about pathogens?
Enteritis = salmonella
Encephalitis = listeria
Septicaemia = salmonella, listeria
What is enzootic abortion?
Chlamydophila abortus
Extracellular infectious phase are elementary bodies
What are the clinical signs of enzootic abortion in ewes?
- Rarely see any ill effects in ewes
- Abortion approximately 2-3 weeks before term
- Premature/weak lambs
- Live lambs which survive
- Very rarely retained placenta
- Vaginal discharge after abortion
What is the pathology behind enzootic abortion in ewes?
- Chlamydial growth in placenta from 90 days
- Disruption in placental production of progesterone
- Premature labour
- Lesions are seen mainly in the intercotyledonary space
Describe the epidemiology and transmission of enzootic abortion in ewes.
- Infected foetal membranes are the source of elementary bodies
- Copious uterine discharges
- Newborn lambs wet with foetal fluids – ewes are maternally driven to lick lambs, spreading infection
- Intestinal carriers
- Subsequently excrete chalmydiae during oestrous
How is enzootic abortion in ewes prevented and controlled?
- Isolate ewes that have aborted/had weak lambs
- Destroy dead foetuses/dead lambs
- Collect placentas and destroy
- Disinfect lambing pens
- Keep a closed flock
- Buy replacement ewes from EAE free flocks
Which antibiotic in the face of an enzootic abortion outbreak in ewes should be used and why?
Long acting oxytetracycline IM, repeated at 10-14 day intervals. Suppression of chlamydial multiplication extends the duration of threatened pregnancies
What are the vaccines availabel for enzootic abortion in ewes?
Inmeva = inactivated vaccines, can use in pregnancy in the face of an outbreak
Enzovax and cevac = live vaccines, can’t use in pregnancy
When should ewes be vaccinated against enzootic abortion?
- Low risk flocks only vaccinate once
- High risk flocks vaccination boost in 2-3 years
- Vaccinate before breeding to replacement ewes
- Can vaccinate bought in ewes where not sure of EAE status, but does not prevent latent infection, but reduces shedding
When should be ewes be kept and when should they be culled and why?
Ewe aborts = solid immunity against abortion, only with small intermittent excretion of Chlamydophila during oestrous. If flock infected some years, keep ewes that have aborted.
If newly infected, cull aborted ewes due to carriage risk.
What are the clinical signs of toxoplasma gondii in ewes in early infection?
Resorption
What are the clinical signs of toxoplasma gondii in ewes in mid gestation?
Abortion/still birth often accompanied by mummification
What is the characteristic of toxoplasma gondii on post mortem examination of sheep?
Characteristic white foci visible on cotyledons and presence of mummified foetus
How is toxoplasma gondii treated in sheep?
Pyrimethamine and sulfadimidine have been used successfully
How is toxoplasma gondii controlled in sheep?
- Chemoprophylaxis - Decoquinate, Monensin
- Toxovax is a live attenuated. Cannot use in pregnant sheep. Care with self-injection
- Control cat breeding and vermin
- Remove dead lambs/placentas to deny access to cats
What are the major differentials of infectious ovine abortion?
Chlamydophila
Toxoplasma
Campylobacter
Salmonella
Listeriosis
Border disease
Q fever – Coxiella burnetti
Leptospirosis
How can horizontal spreading of pathogens during lambing be prevented?
- Synchronised? Provided that hygiene is very good, this will limit horizontal spread
- General hygiene in lambing pens
- Less time pressure on staff
What is the epidemiology of campylobacter abortion in ewes?
- C. fetus fetus is found in the gut of carrier sheep with horizontal spread at lambing
- C.jejuni is found in most birds, contamination of fields/paddocks/water courses, horizontal spread between sheep
How is campylobacter abortion in ewes be diagnosed?
Culture from foetal stomach, liver and placenta, specialist media and conditions
How is campylobacter abortion treated in ewes?
Oxytetracycline LA
Pen/strep
What is border disease?
Pestivirus related to BVD and CSF
What are the clinical signs of border disease?
- Foetal resorption
- Abortion
- Hairy-shaker lambs – persistently infected with virus
- Normal lambs
What is the result of infection 60 days or less of border disease?
Before immunocompetency in the lamb:
Foetal death
Resorption
Mummification
Abortion
Stillbirth
Hairy-shaker lambs
Weak/normal, lambs persistently infected with virus, no antibodies detectable
What is the result of infection 85 days or more of border disease?
After immunocompetency in the lamb:
Foetal death
Abortion
Stillbirth or foetal survival
Weak or normal lambs with antibody to BD, no virus/antigens detectable
What are hairy shaker lambs?
- Small, weak
- Nervous signs from tremors to violent shaking
- Fleece changes in smooth coated breeds as the virus affects the hair follciles
- Skeletal abnormalities
What is the epidemiology of border disease in ewes?
Mainly sheep to sheep transmission by persistent carriers also in semen, can get BD from BVD in cattle or other ruminant pestiviruses
How is border disease diagnosed?
- Abortions/stillbirths
- Hairy-shakers
- Fresh tissues specific immunostaining
What action is taken for a sporadic outbreak of border disease in a flock?
Entire lamb crop should go for slaughter and no replacement animals should be kept, cull sheep suspected of introducing disease.
What action is taken for endemically infected flock with border disease?
Deliberately exposure breeding animals when most are pregnant to known persistently infected lambs, house indoors for at least 3 weeks. End exposure 2 months before the start of the breeding season
What is salmonella abortus ovis?
A sheep adapted strain, late abortion/high lamb mortality, non-specific clinical signs and lesions
What is the epidemiology of salmonella abortus ovis?
Stress causes non-pregnant ewes to excrete in faeces and pregnant ewes to excrete in abortion products
What antibiotics can be used in ewes in the face of a salmonella abortus ovis outbreak?
Long acting preparations, antibiotic sensitivity, supportive therapy
What are the clinical signs of listeriosis in ewe flocks?
Abortion at any stage of pregnancy, may also see other signs within the flock, septicaemia, encephalitis
What is the epidemiology of listeriosis in ewe flocks?
Sporadic cases occur, large outbreaks inevitably associated with silage feeding of housed ewes
What are the treatment and controls for listeriosis in ewe flocks?
Remove silage
Antibiotics may reduce losses
Describe the epidemiology of leptospirosis in sheep.
- Organism is excreted in urine
- Sheep to sheep transmission can occur
- Sheep can act as a reservoir of infection for cattle
How can leptospirosis be treated and controlled?
Pen/strep
Could potentially use cattle vaccine in sheep
What is Schmallenberg virus?
- Orthobunya virus
- Vector borne - midges
What does schmallenberg virus cause?
Late abortion or birth defects in newborn cattle sheep and goats
What is arthropryposis?
Typically hock, limb fixed in position, causes a lot of dystocia.
What is the pathogen causes Q fever?
Coxiella burnetti
What is vaginal prolapse in sheep?
Hormones of pregnancy alter the amount and distribution of collagen and smooth muscle in vaginal wall. Usually occurs 3weeks before lambing.
What are the characteristics of vaginal prolapse in sheep?
- Further eversion until the cervix is visible
- Prolapsed vagina is vulnerable to injury
- Signs of swelling, oedema and congestion ultimately progress to haemorrhage and gangrene
How can vaginal prolapse lead to vaginal rupture in ewes?
Prolapse > neglect > damaged vagina > straining > rupture
Prolapse > obstruction of urethra > distention of the bladder > straining > rupture
How can vaginal rupture progress in ewes?
Vaginal rupture (uncommon) > herniation of caecum ileum colon > death from haemorrhage and shock
Describe the epidemiology of vaginal prolapse in ewes.
- Breed – lowland more than hill
- Litter size – risk of VP increases with litter size
- Age – risk of VP increases with increasing age due to increasing litter size
- Overfeeding
How is vaginal prolapse in sheep treated and managed?
- Anaesthesia – consider use of caudal epidural if straining is severe (lignocaine/xylazine for prolonged anaesthesia
- Lift prolapse and empty bladder
- Clean up prolapsed tissues very thoroughly
- Raise rear end of ewe
- Reduce prolapse carefully, tissue may be friable so be careful
- Subcutaneous purse string suture/Buhner suture around vulva, horizontal mattress sutures
What are the supportive treatments used for vaginal prolapses in sheep?
Antibiotics
Anti-inflammatory analgesics
Check re-pregnancy toxicity
Hypocalcaemia
How are vaginal prolapse ewes controlled?
Mark ewes with prolapse and cull post lambing – 40% will prolapse again
When does uterine prolapse in ewes occur?
Post lambing
What is the effect of prolonged second stage labour in ewes?
Subdural, subarachnoid and extradural haemorrhages around cranial and spinal meninges > reduced mobility and sucking reflex > may cause death
What are the possible causes of intrapartum deaths in lambs?
- Oedema ‘hung lamb’
- Ruptured liver due to vitamin E deficiency
- Fractured ribs – posterior presentation
- Flail chest – all ribs broken at cost-chondral junction
- Fractures due to being trodden/laid on by ewe (post-partum)
Why may a lamb be concluded to be a dead a long time?
Mummification
Autolysis
Collapse of eyeball
TOD = antepartum
Why might a lamb by concluded to have been recently dead?
No thrombus in umbilical artery
Square end to artery
Lungs uninflated
TOD = antepartum
Why might a lamb be concluded to have died from dystocia?
No thrombus in umbilical artery
Tapered end to artery
Lungs uninflated
Localised oedema in prolonged dystocia
Why might a lamb be concluded to have died in the first few minutes?
Thrombus in umbilical artery
Lungs uninflated
Why might a lamb be concluded to have died in the first few hours?
Lungs inflated
Navel cord wet
Hoof membranes still present
Why might a lamb be concluded to have lived a few days before death>
Hooves hardened
Navel cord shrivelled
What are the most common causes of neonatal losses in lambs?
- Weakness at birth
- Failure to sick – leads to hypothermia and lack of colostrum protection against neonatal disease
- Disease or undernutrition in periparturient ewe or if ewes are in poor body condition
- Hypothermia
- Water mouth
- Diarrhoea
- Naval/joint ill
- Congenital disease
- Haemolytic anaemia
- Sub-capsular liver rupture
- Predation
Why may a lamb have weakness at birth?
- Small lambs from multiple births
- Placental insufficiency. Placenta is fully grown by 90 days, deficiency before this restricts placental growth and ability to transfer nutrients.
- Lamb growth
- Supervision at lambing
- Congenital diseases: toxoplasmosis, border disease
- Iodine or copper deficiency,
How is moderate hypothermia treated in lambs?
37-39˚C – dry and feed colostrum by stomach tube
How is severe hypothermia treated in lambs under 5 hours old?
Unlikely to be hypoglycaemic. Warm in warming box to 37˚C, then feed with colostrum (50ml/Kg)
How is severe hypothermia treated in lambs over 5 hours old?
Assume will be hypoglycaemic. Need to give energy first before warming them otherwise may have hypoglycaemic fit.
When should stomach tubing not be done in lambs? What else is used?
Never use a stomach tube for very weak/unconscious lamb. Give intraperitoneal injection of glucose
How are weak lambs avoided?
- Use appropriate breed for environment
- Adequate ewe nutrition
- Adequate iodine
- Good supervision at lambing
- Control toxoplasmosis and border disease
- Give weak lambs 60-100ml colostrum.
- Provide heat lamps
How is a cold, wet environment for lambs avoided?
- Provide access to shelter/housing
- Emergency shelter can be made from straw bales
- Use of lamb macs, which also confuse foxes
How can you make sure lambs suck?
- Good supervision
- Check ewe has milk lambs
- Extra supervision of ewe lambs
- Choose breed with good mothering ability
- Make provision for orphan lambs
What can result from bacteria entering the navel of lambs?
- Haematogenous spread
- Swelling of navel
- Meningitis
How is navel ill treated?
- Navel abscess
- Lance and irrigate with sterile saline and perfuse with antibiotics
- Liver abscess
- Hopeless cases – meningitis
- Early treatment with high doses of antibiotics
- Ensure lamb does not damage itself
How is navel ill controlled?
Dress navels with tincture of iodine asap after birth. Dry well-bedded pens
What is joint ill in lambs?
- Very painful as bone is affected leading to osteoarthritis
- Lambs under 4 week sold
- Often become recumbent
How is joint ill treated in lambs?
- Need to use antibiotics that perfuse the joint cavity for 10 days to eliminate infection from joints
- Joint flushes – irrigate with sterile saline and perfuse with antibiotics
- Pain relief
What are the infectious disease of lambs?
- Border disease
- Daft lamb disease – hereditary abnormal cerebellar development, lambs appear stupid, ataxic with intention tremor
- Swayback – weak, ataxia, particularly hindlimbs, die within 3-4 days
- Entropian – treat with clips, sutures, sterile paraffin, antibiotic injection
- Red foot – loose hoof cases. Cull
How can cattle colostrum cause haemolytic anaemia in lambs?
- Cow colostrum fed to lambs or kids in certain situations
- May contain antibodies to sheep blood group antigens.
- The absorbed bovine IgG attaches to sheep red blood cells and to their precursers in bone marrow
- These are recognised as foreign and are destroyed
What are the clinical signs of haemolytic anaemia?
Dull
Lethargy
Anaemia
Jaundice
How is haemolytic anaemia treated in lambs?
- IV blood transfusion
- IP blood
- Blood collected and mixed with 10% of 3.8% sodium citrate.
- Given as for glucose
- Antibiotic cover
- Iron dextran
How is haemolytic anaemia
Pool colostrum as it will distribute out any anti-sheep IgG from a single cow. Record
What are the characteristics of sub-capsular liver rupture?
- Found dead with no evidence of trauma
- Associated with low vitamin E status
What are the characteristics of general debility in ewes?
- Increased incidence of lamb rejection – sick ewe too ill to bother with lambs
- Reduced colostrum production
- Reduced milk production
How do you investigate ewe mortality before lambing?
Check for signs of impending abortion, scouring, evidence of recumbency
How do you investigate ewe mortality at lambing?
Check whether lambing has commenced, skill of shepherd, evidence of trauma, neglected vaginal or cervical prolapse or prolapse of intestines
How do you investigate ewe mortality after lambing?
Check for bruising, haemorrhage, severe swelling or discolouration (clostridial infection), metritis or acute mastitis.
What is the evidence of pregnancy toxaemia?
Fatty liver
Ketones in urine
Multiple pregnancy
What is the evidence of ewe death before parturition?
Cervix closed
What is primary pregnancy toxaemia?
Due to a decline in the plane of nutrition during late pregnancy or a temporary period of fasting (such as diet change, transport, adverse weather conditions).
What is fat-ewe pregnancy toxaemia?
BCS over 3.5. It is thought that excessive intra-abdominal fat limits rumen capacity and thus feed intake.
What is starvation pregnancy toxaemia?
Seen in underconditioned animals that have undergone a long period of undernutrition
What is secondary pregnancy toxaemia?
Develops secondary to concomitant disease in the ewe (such as dental disease, fasciolosis, chronic wasting diseases)
What are the early clinical signs of pregnancy toxaemia?
Dull
Reduced appetite
Separate from the flock
What do clinical signs of pregnancy toxaemia progress to?
- CNS signs (hepatic encephalopathy)
- Appear blind – negative menace reflex but pupillary light reflex is okay. Central blindness
- Wander aimlessly
- Head pressing
- Ataxia
- Trembling/twitching of ears
- Champing jaws
- Frothing at the mouth
- Smell ketones
- Ewe becomes recumbent and dies
When may you get transient improvement in the ewe with pregnancy toxaemia?
Sometimes if foetus died, may get transient improvement in ewe, leading to decomposition of the foetus, which leads to toxaemia and ewe death.
How do betahydroxybutyrate (ketone) levels change in pregnancy toxaemia?
- Blood BHB levels >1.1 mmol/l are abnormal and are consistent with OPT
- Levels in clinically affected animals are often >3 mmol/l
- The best sample to take to confirm hyperketonaemia is aqueous humour
- β-hydroxybutyrate (BHB) level >2 mmol/l is considered diagnostic
- BHB >0.8 mmol/l is considered supportive
What are the characteristics of pregnancy toxaemia on post mortem examination?
- Fatty infiltration of liver
- Liver appears swollen, pale and friable due to fatty infiltration, swollen/full gallbladder
- Betahydroxybutyrate (BHB) in aqueous humour >2.5mmol/l
How can pregnancy toxaemia be treated?
- Correct hypoglycaemia – 50-150ml warmed 40% dextrose IV
- Glucose precursors orally for 4 days, propylene glycol for ketosis
- Offer palatable feed – beet, corn
- Reduce glucose drain with glucocorticoids, stimulate gluconeogenesis
- Stimulate the appetite with anabolic steroids – correct acidosis, give sodium bicarbonate IV
How can you protect the rest of the flock from pregnancy toxaemia?
- Increase feed available
- Increase trough space
- Separate over thin/fat ewes and feed appropriately
- Give high quality forage
- Scan ewes
- Avoid stress in late pregnancy
What is the aetiology of milk fever/hypocalcaemia in ewes?
Inability of the ewe to mobilise calcium from the skeleton sufficiently rapidly at times of stress. Occurs in late pregnancy and first few days of lactation. Follows stress
What are the clinical signs of hypocalcaemia in ewes?
- Initially restless
- Unsteady walk
- Trembling
- Rapidly become dull and recumbent
- Fast shallow respiration
- Sternal recumbency with head turned towards flank
- Often bloated
- May prolapse vagina
How is hypoglycaemia treated in ewes?
Calcium borogluconate 100ml 20% solution IV (or SC) or 50ml of 40% solution SC
How is hypocalcaemia controlled in ewes?
- Adequate calcium in diet
- Vaccinate 4 weeks before lambing
What is post-partum hypomagnesaemia?
- No body reserves of magnesium, animals are dependent on continued dietary intake
- Seen 4-6 weeks after lambing
- Potassium/ammonia fertilisers decrease magnesium absorption into foliage
When do clinical signs of hypomagnesaemia occur in sheep?
When plasma concentration is below 0.5mg/dL/0.2mmol/L
What are the clinical signs of hypomagnesaemia in sheep?
- Often found dead
- Dull but if disturbed, become excitable
- Develop muscle tremors and staggering, unsteady gait
- Collapse and lateral recumbency
- Opisthotonos
- Often nystagmus and frothing at mouth
How is hypomagnesaemia treated in ewes?
25ml magnesium sulphate SC, do not give magnesium sulphate IV, applies to cattle and sheep as it will stop the heart, but can give IV if you dilute Mg into Ca.
How is hypomagnesaemia prevented in ewes?
Magnesium supplements in feed, water, mineral blocks, licks or powders.
Magnesium bolus – these contain copper so do not supplement copper
Where do the economic costs of mastitis in ewes comes from?
- Death from peracute mastitis
- Replacement ewes
- Lamb starvation
- Vet treatments
- Reduced growth rates
Which pathogens cause acute mastitis in ewes?
Manheimia haemolytica and staphylococcus aureus – these have necrotising toxins
What are the predisposing factors of acute mastitis in ewes?
- Leaking teats
- Damaged teats
- Orf infection
- Spread infection by dirty hands when shepherd check for colostrum
What are the clinical signs of acute mastitis in ewes?
- Hungry lambs
- Apparent hind leg lameness
- Swollen, red, hot udder
- Pyrexia
- Udder becomes purple and cold and clammy to the touch
- Gangrene will lead to slaughter
How is acute mastitis treated in ewes?
- Remove lambs
- Parental antibiotics – oxytetracycline
- NSAIDs
- IV fluids for endotoxic shock
How is acute mastitis in ewes controlled?
- Vaccination allows prevention of acute cases and reduced somatic cells counts in sub-clinical mastitis
- If udder is full of pus can remove teat
In the absence of clinical signs, how is subclinical mastitis detected?
- California mastitis test
- Culture of bacteria
- Post-weaning the udder may be a bit lumpy/distorted
How is subclinical mastitis in ewes controlled?
(Only really done in dairy sheep) dry cow intramammary tube into each gland
How is subclinical mastitis in dairy ewes managed?
- Cull animals with persistent high CMT and udder lesions
- Post milking teat dipping and use of antibiotic tubes at drying off
- Vimco is a staph mastitis vaccines
