Sheep Flashcards
Timing for pregnancy, lactation and dry months in sheep?
Pregnancy: 5 months (Sept/Oct is tupping time)
Lactation: 4 months (March is lambing time)
Dry: 3 months (June/July is weaning, lamb produced July-Dec)
What makes up Pedigree, hill and lowland flocks?
Pedigree - pure bred hill/upland/lowland for own replacement or to sell, terminal sires
Hill - pure bred females, cross breeding females to sell (cross with leicester breeds), males for meat
Lowland - ewes often cross bred, mated with terminal sires, produce fat lambs for sale/meat
Store lambs - buy fattening lambs and finish for meat
Characteristics of sheep hill breeds?
Hardy Good mothering One lamb/ewe Male offspring for meat Females kept as replacements or sold to upland farms to be crossed with long wool breeds - border or blue faced leicester
Characteristics of sheep upland breeds (long wool)?
Bigger carcass Fast growth Prolificacy Female hill sheep crossed with male long hair breed Blue face X = mile Border X = half bred Females sold to lowland farms as ewe replacements Males sold for meat
Characteristics of sheep lowland farms?
Buy in mules or half bred ewe replacements Or breed their own Cross with terminal sire breeds All lambs for meat Keep ewes for 4 crops of lambs then cull
What are the problems with the UK sheep stratification structure?
Little genetic improvement in UK flocks
Breeding based on size and appearance rather than economically valuable traits
About intensive
Ideal sheep characteristics?
Lamb vigour
Good mothering
Growth rates
Resistance to disease
How to use Estimated Breeding Values (EBVs)?
Halve the value for the offspring
Weight EBV +6 = genetic potential to be 6kg heavier (3kg for offspring)
Litter size is percentage more lambs
Gross and net margin equations? (sheep)
Gross margin = output - (variable costs + replacement costs)
Net margin = gross margin - fixed costs
What are the targets for: ewe mortality, ewe culling rate, ewe:tup ratio, replacement rate,lamb mortality scanning to birth, lamb mortality birth to turn out (1 week old), lamb mortality turn out to sale, lamb mortality overall birth to sale, lamb growth rate?
Ewe mortality: 1-3% Ewe culling rate: <30% Ewe:tup: 40:1 Replacement rate: 20-25% Lamb mortality scanning to birth: 6% Lamb mortality birth to turnout: 6% Lamb mortality turnout to sale: 2% Lamb mortality overall birth to sale: 8% Lamb growth rate: 0.2-0.25kg/day
Condition score targets for upland, lowland and hill sheep at tupping, mid pregnancy, lambing and weaning?
Tupping -> mid pregnancy -> lambing -> weaning
Upland: 3 -> 2.5 ->2.5 -> 2
Lowland: 3.5 -> 3 -> 3 -> 2.5
Hill: 2.5 -> 2 -> 2 -> 2
What is flushing? What are the static and dynamic effects?
Increase feed to ewes pre-tupping to increase BCS by 0.5 to improve number of eggs produced
Usually with grass management
May need supplementary concentrates
Static effect = ewes in better BCS have higher ovulation rate
Dynamic effect = increasing live weight gain gives higher ovulation rate
Why should the BCS be maintained/reduce by 0.5 around mid-pregnancy?
Placenta develops
If underfed = small placenta = low lamb birth weight
When does most of sheep foetal growth occur? Why is it difficult to feed ewes more towards lambing?
70% in last 5 weeks
Ewe’s rumen capacity is decreasing due to foetus size
What to feed sheep in late pregnancy? How?
Supplementary feeding usually required for last 6-8 weeks
If later lambing (April/May) may only need well managed grass
Monitor BCS and/or metabolic profiles (3 weeks before lambing)
Feed in groups - 1.2m squared per ewe, 50/pen, group by scan/BCS/lambing date
Good access to top quality forage is key - hay/silage ad lib
Max 1kg concentrate/day, 0.5kg/feed
Water!
Consider vitamins and minerals
Trough space - ad lib forage 15-20cm/ewe, concentrates 45-60cm/ewe
Best to feed 1/3 of ewes ad lib forage at once, concentrates all at once
Pen first time ambers separately
Consider floor feeding concentrates
TMR
What are common problems with sheep nutrition?
Thin Broken mouth Old Concurrent disease - worms, lameness etc Poor quality forage - acidic, mouldy, wet, low feed value Overcrowding Inadequate quantity Inadequate trough space Acidosis - max 0.5kg/feed No access to water
Problems with fat ewes in pregnancy?
More prone to pregnancy toxaemia More dystocia More likely to prolapse Large foetuses can cause dystocia Oversized lambs have higher mortality Fat is expense to put on
3 main problems if lack of/poor quality colostrum for lambs?
Hypothermia
Starvation
Infection
When do lambs start eating grass and when weaned
Start eating grass at 6 weeks old
Weaned at 12-16 weeks (some evidence better if 6-8 weeks?)
What is pregnancy toxaemia? Risk factors?
= under-nutrition/energy deficiency/hypoglycaemia/hyperketonaemia Thin Fat (don't eat enough) Stress Late pregnancy Broken mouth Often fatal unless treated early
Clinical signs and diagnosis of pregnancy toxaemia?
Separate from group Inappetent Apparent blindness Tremors of face and ears Progress to recumbency Dead foetuses Death 0-10 days Diagnosis: clinical signs and BOHB > 3mmol/l
How to treat pregnancy toxaemia of sheep? And if not improving?
Early! To prevent hypoglycaemic brain damage
Separate
Give highly palatable feed - fresh food and water
IV glucose
50-100ml 40% dextrose - can repeat after couple of hours
Propylene glycol - 50ml twice daily (max 2-3 days)
If late/not improving:
- PTS
- Abort ewe after 135d pregnancy with 16mg dexamethasone
- C section only if ewe viable, otherwise PTS
- poor prognosis
Flock prevention of pregnancy toxaemia?
Ensure adequate feeding
BCS 6-8 weeks before lambing
Feed according to number of foetuses/BCS
Monitor ketone body levels 2-3 weeks before lambing
Cull broken mouth ewes
Avoid sudden changes/stress in last 6 weeks of pregnancy
When is hypocalcaemia seen in sheep pregnancy? Risk factors?
Usually pre-lambing 6 weeks onwards (not always)
Often stress induced - handling, gathering for vaccinations etc
Changes of diet/pasture/snow/water deprivation
Acidosis with cereal diet
Older ewes
Rapid growing lush pasture
Clinical signs of hypocalcaemia in sheep?
Initial weakness and excitement Progresses to recumbency Dilated pupils Constipated Bloated Collapsed Flaccid paralysis Comatose -> death
Treatment for hypocalcaemia in sheep?
Slow IV 40-80ml 20% calcium boroglucoronate or very slow 20-40ml 40% - rapid response
SC 1ml/kg 20% CaBG (50-100ml) warm - slow response
Monitor as may relapse
History and clinical signs for hypomagnesaemia (staggers) in sheep?
History: post lambing/peak lactation, lush grass/bare pasture
Rapid onset
Sudden death usually
Neurological signs - excitable, tremors, recumbent, hyperaesthesia, convulsions, death/found dead
Treatment for hypomagnesaemia (staggers) in sheep?
IV 40-80ml 20% Calcium
SC 50-80ml 25% MgSO4
Differential diagnoses of sick/recumbent ewes at lambing time?
Hypocalcaemia Hypomagnesaemia Pregnancy toxaemia Listeria Mastitis Metritis
What drugs to use for dystocia in sheep?
NSAIDs
Epidurals
Antibiotics
Give lamb colostrum
When is a simple embryotomy done for sheep? How?
Dead lambs which are not possible to deliver per vaginum
Lots of lube
Remove forearms - cut through skin around leg above carpus, then up towards elbow, undermine attachment of shoulder to chest wall, pull leg off
Repeat other if necessary
Indications for a sheep caesarean? Contraindications?
Over sized lambs Ringwomb (failure of cervix to dilate) Vaginal prolapse Foetal monster Malpresentation
Contra: rotten lamb/smelly fluids unless can exteriorise uterus (embryotomy or euthanasia best)
Drugs for sheep caesarean section? Local methods?
Broad spectrum antibiotics (5 day coverage)
NSAID
Local anaesthetic - local infiltration (40ml total), inverted L block or paravertebral T13, L1, L2, L3, 5ml procaine/site), sacra-coccygeal epidural (with xylazine)
Method of sheep caesarean?
Incise half was between last rib and wing of ileum, 10-15cm below transverse processes
15cm incision
Skin and SC tissue with scissors
External and internal abdominal oblique, then lift transverse and peritoneum before incising (so don’t puncture rumen)
Grasp uterine horn and exteriorise
Incise 10-12cm with scissors
Remove lamb
Check for other - reach into other horn, can make another incision if needed
Suture uterus with continuous inverting pattern - catgut, clean, can do 2 layers
Peritoneum and transverse, then internal and external abdominal obliques with continuous simple catgut
Skin - ford interlocking, simple interrupted or other, nylon
Blue/yellow spray
Can give sheep oxytocin after to involute uterus and protect the sutures (1-2ml)
Feed lambs!
Risk factors for metritis in sheep?
dystocia - poor hygiene, dead lambs
Post abortion
Clinical signs of metritis in sheep?
Dull, recumbent, depressed
Toxaemia - congested mucous membranes
Red/brown or purulent vaginal discharge
Treatment of metritis in sheep? Prevention?
Antibiotics and NSAIDs
Poor prognosis
Prevent with hygiene
When is vaginal prolapse usually seen in sheep? Problems with it?
Common in last 4 weeks of pregnancy (1-2%)
Vagina or vagina and cervix, may include bladder
Inflamed swollen infected tissues, obstruction of bladder, urine retention
Can be fatal if untreated
Suggested causes of vaginal prolapse in sheep?
Prolific breeds > hill breeds Litter size Age Obesity Hypocalcaemia 35-40% will re-prolapse
Treatment for vaginal prolapse of sheep pre-lambing? And cervix post lambing? Prevention?
Retention devices - discomfort, irritation of mucosa, secondary infection
Harnesses - avoid pressure sores
NSAIDs
Long acting antibiotics
Surgery
Cervix post-lambing - same and mark for culling
Prevention - difficult as cause uncertain, cull as increased risk, put harness on before occurs next lambing, review poss risk factors
Procedure for vaginal prolapse surgery of sheep?
Epidural anaesthetic - reduce straining, analgesia, sacra-coccygeal or first intercoccygeal space, procaine (short action) or procaine and xylazine (24h+)
NSAIDs and antibiotics
Clean and assess - mild chlorhexidine
Replace prolapse - gently with palm of hand, raise back end of ewe
Suture with obstetrical tape, purse string (leave 1.5cm opening, burner
Mark ewe, remove sutures before lambing
What is a complication of vaginal prolapses in sheep? What to do?
Rectal prolapse
Epidural, replace, purse string suture
Tissue non viable - amputate rectum
Treatment of uterine prolapses after lambing?
Epidural Clean Remove or trim placenta Replace carefully and fully evert Suture Oxytocin Antibiotics NSAIDs Calcium?
Impact of mastitis in sheep?
Ewe mortality
Ewe premature culling
Lamb mortality
Lamb poor growth
Most common 2 causes of mastitis in sheep in the UK? How are they transmitted?
Staph aureus - via teat skin
Mannheimia haemolytica - via lamb’s mouth
Udder and milk clinical signs of peracute/acute/chronic/subclinical mastitis in sheep?
Peracute - cold blue +/- necrotic in gangrenous mastitis
Acute - hot, red, painful, swollen
Chronic - udder may be light with hard swellings (abscesses)
Subclinical - abnormal milk appearance (clots) and composition
Systemic clinical signs of mastitis in sheep?
Toxaemia - congested mucous membranes? Pyrexia Tachycardia Rumenal stasis Lameness Recumbency Hungry lambs
Risk factors for mastitis in sheep?
Nutrition - undernutrition in late pregnancy/lactation, low BCS, vitamin E/selenium deficiency
Concurrent disease - fluke, jones, worms, dystocia etc
Prolificacy - multiple lambs
Older ewes
Udder conformation - abnormal teat position
Udder abscesses
Teat lesions - orf, over-suckling, chilling (chapped teats)
Genetics
Hygiene
Milking practices (dairy sheep)
Treatment of mastitis in sheep?
No real evidence basis
Gangrenous - euthanasia (v poor prognosis)
Acute - systemic antibiotics (ideally based on c+s, first line amoxicillin for 5 days, tilmicosin licensed), strip udder to remove toxins, NSAIDs, IV fluids, supportive care
Chronic - cull
7 mastitis prevention points in sheep?
- Ensure adequate ewe nutrition pre and post lambing
- Wean lambs at 12-16 weeks abruptly
- Control orf
- Control concurrent disease e.g. fluke, worms
- Don’t turn out ewes with triplets
- Cull ewes over 7/with broken mouth/udder lumps/abnormal teat positions
- Ensure good bedding and hygiene in sheds
When is the sheep breeding season?
August - December
What is the difference between spring and christmas lamb management?
Spring - easy management, essential for hill and upland (limited housing, later grass growth)
Christmas - intensive management (housing essential), better lamb prices at easter market
What is responsible for the seasonality of sheep breeding?
The pineal gland
Tryptophan –> serotonin –> melatonin
Melatonin only secreted during hours of darkness
Hypothalamus is sensitive to melatonin during the late afternoon
Coincidence of hypothalamic sensitivity and melatonin = short day breeders
Oestrogen negative feedback
How many follicular waves do sheep have?
2-5
50% have 4
35% have 3
How long should a ram remain with ewes for natural service? Why?
At least 35 days
Ewes ovulate and are receptive to the ram every 16-18 days
So allows for ewes that didn’t conceive when first mated to be bred again at next heat
Can saddle the ram to see mated ewes
How is AI done in sheep and why? When?
Laparoscopy due to cervical anatomy
12-24 hours after oestrus detected
What is the ‘ram effect’?
Introduction of a ‘novel’ male or after 2+ weeks of male absence
Induces cyclicity earlier in the season
Can synchronise cycling sheep to some extent
2 peaks of oestrus activity after male introduction
First ovulation ‘silent’ for some
19 days first ovulation for others
25 days second ovulation for those who had silent ovulation
Use vasectomised ram so cannot fertilise
Breeding males then later introduced
How can sheep breeding seasonality be manipulated with melatonin?
Melatonin implant at base of ear
- Suffolk/Cross - use from mid May to late June to introduce ram in late June/July
- Mules/halfbreds - use from early June to late July to introduce ram from mid July to late August
- Day 1: 30 weeks before want to lamb - move ewes from sight/smell/sound of rams
- Day 7: Implant ewes
- Day 42: 30-40 days after implantation - introduce rams
- Delay of 14-21 days before mating, peaks at 25-35 days
- Use vasectomised ram for first 14 days to get more compact lambing period
How can sheep breeding seasonality be manipulated with progesterone sponges?
Chronogest = synthetic progesterone in a sponge, place intavaginally for 12-14d to get into bloodstream
Combine with PMSG (FSH activity) injections at time of sponge removal to stimulate cyclicity out of season
Oestrus 36-72 hours after sponge removal
1 ram:10 ewes
Ram in 48 hours after sponge out (not earlier)
Lamb in 3 week period, most in 7 days
Also CIDR now licensed (real progesterone so can measure?)
How can sheep breeding seasonality be manipulated with prostaglandin?
Can use to cause luteolysis and induce oestrus in cycling animals
Not authorised but can use half of cattle dose
CL refractory to PG for 2-4 days
Oestrus in about 40 hours
2 PG injections 7-11 days apart induces 95% of ewes in 72 hours
Some data suggests lower pregnancy rates than progestergens
How can lambing be induced if service date known?
8ml Dexamethasone injection from day 140 after ram in
Lamb about 40 hours later
Not authorised
What BCS should rams be before breeding? How long does sperm take to develop?
BCS 3.5
60+ days
Sheep gestation length?
145 days
How many times maintenance should ewes be fed at conception-42days/42-90days/90days?
Conception-42 days: maintenance only
42-90 days: maintenance + 2MJ/day (grass/forage)
90days-parturiton: good nutrition needed for rapid foetal growth/colostrum quality and quantity/prevention of metabolic diseases, feed according to single/twin/multiple, should be 2xmaintenance by lambing time (but reduced appetite in last 2 weeks due to rumen space)
What to make sure to do when vasectomising a ram?
Store the epididymis
Identify the animal (ear tag)
What should the scrotal measurement be of a ram?
30cm
Causes of epididymitis in rams? Prevention?
Actinobacillus seminis Haemophilus somnus Histophilus ovis Treatment unsuccessful! Prevent by growing rams in small groups, graze and rotate to clean paddocks May develop to orchiditis
Physical problems with testicles which may reduce fertility?
Cryptorchidism (rig) - uni or bilateral, need lower temp for sperm to develop, don’t put with too many ewes if unilateral
Testicular degeneration - bilateral unless specific local injury
Testicular hypoplasia - uni or bilateral
What causes scrotal mange of rams? Clinical signs? Diagnosis? Treatment?
Chorioptes bovis - sheep adapted strain
Crusty scabs on lower 1/3 of scrotum
Crake and expose sore, weeping dermis
Sore as get ‘gratification reflex’ when handled
Can occur on lower legs and poll
If extensive then raises blood flow and testes temperature –> testicular degeneration and reduced sperm quality
Confirm with skin scrapes from several locations
Doramectin and diazinon sheep dip effective
What is pizzle rot (balanoposthitis)?
Affects rams and wethers - castrations affect development of area so urinate inside prepuce
Ranges from small ulcers and discharge at prepuce to scanning?? causing blockage of the prepuce and fly strike
Corynebacterium renale - also associated with off
Produces ammonia from urea in urine
Pizzle rot risk factors, prevention and treatment?
High protein concentrates and lush grass = risk factors
Access to water, salt or ammonium chloride to increase drinking and acidify urine
Isolate animals to reduce environmental contamination
Clip wool away and clean area
Systemic antibiotics and fly treatment
When do 49% of lambs die? :(
At lambing (0-48h)
What are the main causes of lamb mortality/morbidity?
Pre-partum - abortion/still birth Intra-partum: dystocia: - Birth trauma - Ruptured liver - Fractured ribs - Brain haemorrhage - Anoxia Post partum: - Hypothermia - Starvation - Infection (e.g. watery mouth, salmonella, cryptosporidium, septicaemia, meningitis, joint ill, clostridial disease) - Predation - Accidents - Congenital defects
Risk factors for lamb mortality?
Maternal factors - genotype 'mothering ability', experience, ewe health, nutrition, stress, ewe health Prenatal infections Lamb birth weight - genetics, nutrition Dystocia Colostrum/milk Hygiene - pens, lambing, equipment, navel dipping Shepherds - experience, number Weather
Problems from no colostrum?
Inadequate immune system
No energy
Die of hypothermia, starvation or infection
How much colostrum does a lamb need? How to check? When to supplement?
50ml/kg in first 6 hours (200ml)
200ml/kg in first 24 hours (1L)
Check - full belly, ewe has colostrum, watch for suckling
Supplement if needed - triplets, orphans, thin ewes, dystocia, weak lambs
What is the ideal and minimum plasma protein level of lambs from colostrum?
Ideal > 60g/L
Minimum > 45g/L
Suckling from ewe is best!
Risk factors for poor colostrum intake?
Concurrent disease - dystocia, lameness Undernutrition of ewe Breeding - mothering, lamb vigour Age of ewes Multiple births Lambing environment - stress, mis mothering, shepherding skills, poor weather
Colostrum substitute options?
Ewe colostrum - can use oxytocin to assist milking out single ewes
Goat colostrum is good - similar energy, good Ab spectrum, but CAE negative herds
Cow colostrum - 2 hours of calving, jones and TB negative, vaccinated for clostridia, less energy so need 30% more
Commercial colostrum - variable quality, often good energy and protein but poss less Ig, often dried cow colostrum
Protocol for feeding orphan lambs?
50ml/kg colostrum in first 6 hours Total 250ml/kg in first 24 hours Week 1 - 300ml milk (warm) 3-4 x daily Week 2 - 1-1.25L twice daily Hay and creep feed from week 1 Wean 4-6 weeks at 15kg 0.4m squared/lamb
When is hypothermia of lambs usually seen?
Early lambing flocks/outdoor lambing
Usually in first 6 hours
Can use brown fat for 6 hours
Normal rectal temperature for lambs?
39-40C
Risk factors for hypothermia of lambs?
Bad weather Weak Premature Triplets Dystocia Infection Poor ewe nutrition Mis mothering
What to be careful to avoid when warming/giving colostrum to lambs?
Warming a hypoglycaemic lamb without giving glucose first will cause a hypoglycaemic fit
Oral administration of fluids to hypothermic lambs can cause regurgitation and inhalation pneumonia or asphyxia
So need I/P glucose!
How to treat a lamb with hypothermia <37C? And clinical signs?
Will be severely weak, depressed, arched back, stands close to dam, recumbent Dry I/P 20% glucose 10ml/kg Warm to 37C Colostrum 50ml/kg Warm to 39C Return to ewe Monitor Shelter
How to treat a lamb with hypothermia 37-39C? And clinical signs?
Moderately weak but can still suckle and hold head up Dry Feed warmed colostrum Check ewe's milk status/health Return to ewe Provide shelter Supervise
How to do intra-peritoneal glucose injections for lambs?
Strength is 20%
10ml/kg warm
Use 19G 1’’ needle
Hold lamb by front legs
Just below and to one side of navel
Warm in box with fan heater under wire mesh
When lamb is conscious and able to suck, feed 150-200ml colostrum
Prevention of lamb hypothermia?
Breeding - breed from good mothers, hardy vigorous lambs
Ewe nutriton - lamb birth weight, brown fat, colostrum
Provide shelter
Identify at risk lambs and give special attention
Lamb coats
What causes watery mouth in lambs? Clinical signs?
E.coli - lack of colostrum or delay allows gram negative bacteria to multiply unchallenged, bacteriaemia, bacterial death releases endotoxins, lamb dies of endotoxaemia
Within first 3d of birth
Depressed, profuse salivation, swollen abdomen, collapse, dehydration, death
Risk factors for watery mouth in lambs?
High litter size Low birthweight Early castration Inadequate colostrum Poor hygiene Later in lambing period
Treatment for watery mouth in lambs?
Oral fluids - 50ml/kg every 6 hours
NSAIDs - anti-endotoxic effects
Broad spectrum antibiotics - amoxicillin/clavulonic acid, spectinomycin
Prevention of watery mouth?
Nutrition/BCS of pregnant ewes
Colostrum - check, policies
Hygiene of environment
Don’t castrate until >24h (as would sit around for few hours as painful)
Check/monitor sensitivity
Metaphylactic oral antibiotics - spectinomycin in outbreak scenarios
Policy for antibiotic use for watery mouth?
Targeted oral antibiotics for prevention of WMD may be appropriate if:
- Lambs born into groups where there ave been previously recent clinical cases
- Triplets or low birth weight lambs born into challenging environmental conditions or towards end of lambing period
But whole flock treatment of all lambs at birth should be avoided
Causes of lamb neonatal diarrhoea?
Lamb dysentery - Clostridium perfringens E.coli Rotavirus Cryptosporidium parvum Salmonellosis (typhimurium or dublin)
What agents cause joint ill (infectious arthritis) in lambs in the UK?
Streptococcus dysgalactiae
Erysipelothrix rhusiopathie
Tick pyaemia (Staph aureus)
Anaplasma phagocytophila?
Sources of infection for Strep dysgalactiae causing joint ill in lambs?
Unknown?
Theory:
- Low carriage rate in ewes (milk, report tract?, faeces)
- Direct contamination of her lambs and indirect to other lambs
- Contaminated lambing environment (bedding, equipment etc)
- Builds up through lambing
Route of infection unsure - oral? milk? faecal? bedding? respiratory? cutaneous has good evidence - exposed surfaces such as umbilicus and wounds (docking and castration)
How old are lambs affected by Strep dysgalactiae joint ill? Clinical signs?
<4wo
Mild or no pyrexia
Moderate to severe lameness
Single joint (50% of cases) or 2 or 4
Paresis, intra-vertebral joints affected
Carpal, hock, fetlock, stifle most common
Joints swollen, hot and painful
Progress to chronic thickened joints, restricted movement, poor growth
Radiographically thickening of joint capsule, osteophytic changes
Treatment of Strep dysgalactiae joint ill of lambs? (also for meningitis)
No evidence base for treatment or control
5 day course early in disease - suggested repeat once if required, euthanise if not better
Penicillin drug of choice - not sensitive to tetracyclines
NSAIDs
Dexamethasone
Prevention/control of Strep dysgalactiae joint ill in lambs? (also for navel ill and meningitis)
Move all ewes and lambs away from contaminated environment
Hygiene - turnout to pasture, clean+disinfect sheds and pens between ewes, remove placentas and afterbirths, re-bedding frequently, wear gloves when lambing, wash hands between lambing, disinfect all equipment between lambs
Ensure colostrum intake
Navel dipping in 10% iodine by 15mins old and repeat 2-4h later
Metaphylactic treatment of neonatal lambs in outbreaks but don’t continue in successive years
How old are lambs affected by Erysipelothrix rhusiopathie joint ill? Clinical signs?
6 weeks - 6 months old
Polyarthritis (fibrinous), pyrexia, lameness, stiffness
High morbidity
What type of organism is Erysipelothrix rhusiopathie? How is it spread to cause joint ill in lambs?
Ubiquitous
Commensal and pathogen
Faces, urine, saliva, nasal secretions, carrier animals, wild birds
Environmental contamination
Skin wounds - surgical castration and docking sites, umbilicus?
Post dipping
Treatment and control for Erysipelothrix rhusiopathie joint ill in lambs?
Penicillin daily for 5 days
NSAIDs
Control - clean, dry lambing environment, hygiene of wounds and navels, vaccination licensed for pigs
Clinical signs of navel ill/omphalophlebitis in lambs?
Hunched back Poor body condition Poor suckling Moist, swollen, painful navel Pus from navel Spreads to joints
Treatment for navel ill/omphalophlebitis in lambs?
Poor prognosis
Broad spectrum antibiotics for at least 5-7d (penicillin etc)
Prevention same as joint ill
What causes meningitis in lambs and what are the clinical signs?
Opportunistic bacteria, inadequate colostrum
Weak, depressed, collapsed, fitting
Congestion of blood vessels around the eyes
Prognosis poor
Clinical signs of drunken lamb syndrome? Age affected?
1-3 weeks old
Acute ataxia and uncoordinated tendency to recumbency
Death quickly follows usually within 24-48 hours
Diagnosis of drunken lamb syndrome?
Clinical signs and lab confirmation
Biochemically lambs may be weakly azotaemic and hyperphosphataemic
All have metabolic acidosis due to excess D-lactate (due to colonic fermentation)
Treatment of drunken lamb syndrome?
Sodium bicarbonate dissolved in tap water orally with parenteral long acting amoxicillin
How to treat entropion in lambs?
Treat early - check at birth
Flip out lid, sub-conjunctival injection with penicillin, staples
How to treat atresia ani in lambs?
Use small amount of local Incise skin where anus should be Identify and open blind rectum Evacuate Suture rectal wall to skin
How to treat prolapsed intestines in lambs?
Gaseous GA Surgically repair Clean intestines with sterile fluid Enlarge hole Replace Suture defect Good aftercare
Clinical signs of patent urachus in lambs and treatment?
Umbilicus swollen (ddx hernia/abscess)
Dribbling urine (ddx urolithiasis)
Surgery under GA to locate
Usually need antibiotics as infection common
What is swayback in lambs? When is it seen?
Copper deficiency
When ewes deficient in pregnancy
Clinical signs of swayback in lambs?
Still births
Weak lambs
Characteristic weakness of pelvic limbs
Delayed form in offer lambs
Which sheep breed is prone to swayback?
Scottish blackface
Treatment for swayback?
Copper injections/boluses/capsules
When is iodine deficiency seen in sheep/lambs? Clinical signs?
Ewes grazing pasture or crops with high goitrogens
Newborn lambs - hypothermia, starvation, pot bellied, weakness, death
Thyroid gland goitre in lambs
Late abortion
PM: goitre gland:bodyweight ratio
Prevention of iodine deficiency in lambs?
Treat ewes with potassium iodide 4 weeks pre-lambing or boluses
How much should 1 day old single/twin/triplet lambs weigh?
Single: 5.5-7kg
Twin: 5-6kg
Triplet: >4kg
What indicated dystocia on lamb PM?
Swollen head/tongue Meconium staining Oedema of head and shoulders Fractured limbs and ribs Free blood in carcass Haemorrhages Hepatic rupture
What indicates hypothermia/starvation on lamb PM?
No brown fat
No milk in abomasum
How to monitor weight of growing lambs?
EID and electronic scales, or traditional weigh scales and paper Pick typical group of lambs (known age) Assume 4kg birth weight 8 week weight - 300-500g/day Weaning weight - 300-500g/day Sale weight - 200-250g/day
Causes for individual/few lambs with poor growth?
Low birth weight Border disease Congenital problem Neonatal/chronic infection Inadequate milk - triplets, too little milk, bottle fed, weaned too early
Causes for poor growth in a group of lambs?
Inadequate nutrition Parasitic disease - esp anthelmintic resistance Trace element deficiencies Pneumonoa Lameness - joint ill, CODD, FR/scald Off, scab
Differentials for lambs with diarrhoea?
E.coli Salmonella Clostridium perfringens type B (lamb dysentery) Clostridium perfringens type D (pulpy kidney) Cryptosporidium parvum Coccidiosis Nematodirus battus Parasitic gastroenteritis Acidosis
When is Cryptosporidium parvum diarrhoea seen in lambs/calves? Clinical signs?
Severe outbreaks at end of lambing/calving Intensive systems Lambs 3-7d old Profuse diarrhoea (blood) Dehydration Can be fatal
Diagnosis of C parvum in lambs?
Stain faecal smear C parvum
PM histopathology (definitive)
Check for E.coli
Treatment and prevention of Cryptosporidium parvum in lambs?
Supportive treatment - house, oral fluids (50ml/kg 4-6xdaily)
No drugs licensed
Prevention - use different fields/housing for lambing and calving, move to fresh pasture in outbreak, put newborn animals to clean pasture, improve indoor hygiene
Which Coccidia species affect lambs? How infected?
Eimeria crandalis/ovinoidalis
Non disease causing strains normally in sheep
Source is from ewes or older lambs multiplying
Risk factors for Coccidia in lambs?
High stocking rates Inadequate colostrum Mixing ages Stress Concurrent Nematodirus infection
Clinical signs of Coccidia in lambs? Age affected?
4-8 weeks old Diarrhoea (can be haemorrhagic) Tenesmus Fever Weight loss Death Subclinical - poor growth
Diagnosis and treatment of Coccidia in lambs?
Faecal samples for coccidia count - not speciation to determine if pathogenic strain
House sick animals
Oral fluids (50ml/kg 4-6xdaily)
Diclurazil, toltrazuril - usually group problem so treat metaphylactically
Prevention of Coccidia in lambs?
Reduce risk factors:
Hygiene of pens and feed troughs
Stocking rates
Colostrum intake
Nutrition
Batch rearing - avoid grazing younger and older lambs together
Consider prophylactic/metaphylactic treatment at risk times
When is acidosis of lambs seen? What happens?
Consumption of rapidly fermentable carbohydrates - e.g. sudden introduction of ad lib carbohydrates
Stubble grain crops, wheat and barley
Fall in rumen pH
Lactic acid production
Rumenitis
Metabolic acidosis
Lead liver abscessation, fungal rumenitis and death
Clinical signs of acidosis in lambs?
Sudden death Dull, depressed Reluctant to move Teeth grinding Colic, bloat Ataxia, recumbent Dehydration No rumen sounds Diarrhoea
Diagnosis of acidosis in lambs?
History and clinical signs
Rumenocentesis pH <5.5
Rumen liquor no live organisms
PM
Treatment of acidosis in lambs?
IV fluids - isotonic saline plus bicarbonate Oral fluids by stomach tube Multivitamins Penicillin daily for 10 days Hay Review feeding
Causes of rumen bloat in lambs? Clinical signs?
Uncommon in sheep
Grain, oesophageal obstruction, legumes (frothy bloat)
Left side distension
Differentials to rumen bloat in lambs?
Hypocalcaemia Abdominal catastrophes Peritonitis Ascites Uroperitoneum
Treatment of rumen bloat in lambs?
Stomach tube
Simeticone
Consider rumen trochar
Clinical signs of lamb nephrosis syndrome? Age affected?
2-12 weeks old
Older lambs (>4 weeks) tend to lose condition and have diarrhoea
Stand around water troughs or field drains due to increased thirst
Diagnosis and treatment for lamb nephrosis syndrome?
Raised urea and creatinine, hyperkalaemia
Decreased albumin:globulin ratio
Metabolic acidosis
No treatment found to be effective - tend to waste away and die within a week so euthanasia preferred
Why is cobalt important for sheep?
For red cell development, amino acid synthesis, energy metabolism - constitute of vitamin B12
Clinical signs of cobalt deficiency ill thrift in lambs?
Weight loss Anaemia Slow growth Debility Watery eye discharge
Treatment of cobalt deficiency in lambs?
Cobalt rumen boluses/oral drenches
Vitamin B12 injections
Cobalt in creep feed
Pasture treatment
Clinical signs of selenium deficiency in sheep?
White muscle disease - ill thrift lambs, weakness, collapse, lame
Poor reproductive performance of ewes
Which sheep breeds are more prone to copper poisoning?
North Ronaldsy
Suffolk
Blue faced Leicester
Texels
Difference between acute and chronic copper poisoning?
Acute - ingestion of large amounts
Chronic - ingestion over long time period, stored in lysosomes in liver, capacity suddenly released into circulation, may be precipitated by stress, intravascular haemolysis and jaundice
Clinical signs of copper poisoning in sheep?
Ataxia Head pressing Jaundice Recumbency Death
Treatment of copper poisoning in sheep?
Sodium calcium EDTA
Supportive therapy
Remove feed source
Molybedenum and sulphur added to water
What causes ‘Pneumonic Pasteurellosis’ in sheep? Where does it come from?
Mannheimia haemolytica
Present in nasopharynx of healthy sheep - disease when enters lung
Often secondary to other disease/stress
Clinical signs of Pneumonic Pasteurellosis in sheep?
Pyrexia
Mucopurulent nasal discharge
Cough
Death
Treatment for Pneumonic Pasteurellosis in sheep?
Oxytetracycline/amoxixillin/macrolides - 5-7d
Avoid stress
Consider metaphylactic treatment of groups at risk or treat when signs appear
Prevention vaccine - heptavac P
Which Mycoplasma species can cause pneumonia in sheep? Clinical signs?
Mycoplasma ovipneumoniae
Cough, slight nasal discharge
Diagnosis, treatment and prevention of Mycoplasma pneumonia in sheep?
Diagnosis - history, clinical signs, BAL, PM
Treatment - oxytet long acting
Prevention - ventilation, stocking rates, hygiene
Which bacteria can cause chronic suppurative pneumonia (lung abscesses) in sheep? Clinical signs?
T pyogenes
Usually 1-2 in group
Secondary to pasteurellosis infection/inhalation pneumonia
Chronic weight loss, pyrexia, soft cough, increased resp effort, nasal discharge?
Poor prognosis
Which lungworm species are there in sheep? Clinical signs? Diagnosis? Treatment?
Dictyocaulus filaria
Muellerius capillaris - not thought to be significant
Coughing, dyspnoea
Baermann test - larvae in faeces
Treatment - anthelmintics, antibiotics, NSAIDs, supportive
What defines drug resistance?
<95% efficacy
How resistant are current anthelmintics?
BZs: 80% of farms have resistant strains
Levamisole: 47% have resistant strains
MLs: 30% have resistant strains
How do nematodes cause disease?
Damage gut lining - reduces absorption
Remove nutrients
Remove blood (Haemonchus)
Host immune response
When are Teladorsagia, Trichostrongylus and Haemonchus seen in sheep?
Teladorsagia - peaks early summer
Trichostrongylus - late summer/autumn
Haemonchus - doesn’t survive well over winter but produces lots of eggs (10,000/day/worm) - mid spring-late autumn serious outbreaks
Nematodirus epidemiology?
Lamb to next year’s lambs
Most hatching and release occurs during period of chill, followed by 10-18C (some don’t require chill anymore so causes disease in autumn)
Large numbers of L3 hatch simultaneously
Severe outbreaks of diarrhoea typically 6-12 week old lambs in late spring/early summer
Clinical signs caused by invading L4 - can have disease but no eggs in faeces
Difference between type 1 and 2 Teladorsagia disease?
Type 1 - lambs first grazing season, mid summer onwards
Type 2 - yearlings in winter months, emergence of hypobiotic larvae
Which nematode causes ‘black scour’ in sheep?
Trichostrongylus
What clinical signs does Haemonchus cause in sheep?
Acute regenerative anaemia Chronic hypoproteinaemia Bottle jaw Weakness, collapse Tachycardia Sudden death
Clinical signs of Nematodirus in sheep?
Very acute severe diarrhoea
Can have high mortality
When do sheep begin to gain immunity to nematodes? What does this depend on?
5-6 months old Must have been exposed Nutrition Genetics Stage of production - peri-parturient immunosuppression 2-4 weeks pre-lambing until 6-8 weeks after
What are the methods of action of BZs, MLs, Levamisole, amino-acetonitrile and spiroindoles?
BZs: tubular binding, prevents glucose uptake, ovicidal
Imidathiazoles (Levamisole): ganglion blocking, paralysis
MLs: blocks Cl- and GABA channels, paralysis
Amino-acetonitrile (monopantel): ACTH receptors, paralysis
Spiroindoles (e.g. derquantel): nicotinic cholinergic paralysis
What are BZs effective for in sheep?
Broad spectrum round worms
Tape worms - but not clinically significant in sheep
N battus
Some hypobiosed larvae
Fluke (Albendazole)
But has most resistance - strong probability won’t work
What are MLs effective for in sheep?
Round worms and mites
All injectable forms active against mange mites
When should group 4 and 5 new generation anthelmintics be used?
Don’t keep for best
Use regularly as part of worm control plan, especially as quarantine dose
What are the main causes for the development of anthelmintic resistance?
Treating everything Treatment frequency Over use Underdosing Biosecurity
How is a FEC reduction test done?
10 lambs per group 4 groups - control, BZ, LM, Ivermectin Weigh and mark Pre-treatment FEC Accurate dose of drug 7-14d post-treatment FEC Calculate mean reduction in WEC Should be >95%
Why don’t dose and move?
Would just populate clean pasture with resistant strains so return to contaminated pasture
How to do anthelmintic quarantine strategy?
For all bought in sheep
Dose with monopantel or derquantel and abamectin
Plus moxidectin or doramectin to treat scab
Hold off pasture for 24-48h
Return to contaminated pasture
When to dose sheep with anthelmintics?
At lambing - leave at least 10% untreated
Tupping time - only if thin
Lambs - targeted to weight/FEC/use forecast/clinical signs/Famancha test
What test is used for Haemonchus in sheep?
Famancha test
Uses pallor of eye mucous membranes
Method of collecting samples for FEC of sheep?
Group - same age/repro status/field/AH treatments
Gather loosely in corner of field for 5-10 mins
Collect fresh dung (at least 10 samples)
Keep separate and cool - reach lab in 48h
Some labs accept pooled samples
What tapeworms can sheep get? What are the final and intermediate hosts? Clinical significance for sheep?
Monezia expansa: soft mite -> sheep - uncertain pathogenicity
Taenia hydatigena: cysticercus tenucollis in sheep -> dog - liver damage, condemnation at slaughter
Taenia ovis: cysticercus ovis in sheep -> dog - cysts cause muscle damage and condemnation at slaughter
Taenia multiceps: coenuris cerebralis in sheep -> dog - neurological disease
Echinococcus granulosus: hydatid cysts in sheep -> dog - cysts in liver and lungs, condemnation at slaughter, zoonotic
Which tapeworms are known as the thin necked bladder worm, sheep bladder worm and did worm?
Thin necked bladder worm = Taenia hydatigena
Sheep bladder worm = Taenia ovis
Gid worm = Taenia multiceps
How to control tapeworms in sheep?
BZs for Monezia expansa in sheep
Surgical removal of Taenia multiceps cysts in sheep
Praziquantel every 6 weeks for dogs for all Taenia and Echinococcus granulosus
Don’t allow dogs to stray onto pasture
Don’t allow dog access to sheep carcasses
How many sheep flocks are affected by scald/footrot in the UK?
97%
What is scald? How is footrot graded? When seen?
Scald = interdigital dermatitis = benign footrot = footrot grade 1
Footrot grades 2-4 (progression of scald)
Scald is most common cause of lameness in sheep
Occurs when wet underfoot
What causes scald and footrot?
Dichelobacter nodosus = main pathogen
Fusobacterium necrophorum found in some cases (=polymicrobial)
Clinical signs of scald?
Red/pink inflamed interdigital skin Discharge (white/grey pasty 'scum') Lame No horn under-running No foul smell
What does the progression of scald to footrot depend on?
Virulence and dose of D nodosus
Susceptibility go the sheep
Whether the sheep is treated promptly before separation of hoof horn occurs
Clinical signs of footrot? Infection reservoir?
Progressive under-running of sole of hoof horn, starting at medial aspect of sole and progressing laterally
Grey necrotic pungent smelling horn
Extremely painful -> rapid weight loss (reduced feed intake)
Lameness
Death from starvation and thirst in some cases
Infection reservoir = infected foot (direct/indirect contact transmission)
Characteristics of Dichelobacter nodosus?
Facultative anaerobe
Survives in environment for 7 days
Present in normal sheep feet
Not flagellated
Fastidious gram negative anaerobe
Pathogenesis:
- produces extracellular proteases = key for virulence
- has fimbriae conferring motility and adherence
- fimbrial proteins = highly immunogenic (basis of serotyping)
10 major serotypes: A-I and M
Characteristics of Fusobacterium necrophorum?
Anaerobe
Gut, faeces, widespread in environment
Risk factors for footrot and scald?
Warm Wet underfoot conditions Muddy Housing Gathering Genetics - heritable susceptibility
Treatment for scald?
Topical treatment:
-Oxytet spray - make sure dry before return to grazing
-Footbathing: formalin 3% max, zinc sulphate - must be exposed to infected interdigital area for 2 mins, clean feet beforehand, need correct conc and depth, dry standing on concrete after, repeat after 5-7d if necessary
Systemic:
-LA oxytet - usually not necessary
Diagnosis and treatment for footrot? Control?
Diagnosis based on clinical signs (culture based diagnosis not routine as fastidious)
Treat asap!
Isolate lame sheep
Treat individuals/groups
Injectable long acting ABs best - LA oxytet cure rate 70-80%, may need to repeat until clinical cure
Footbathing: formalin, copper sulphate
DO NOT TRIM FEET!
Control:
- footbathing
- vaccination: based on fibril proteins
- biosecurity, isolation and selection for resistance (culling?)
What percentage of UK farms have CODD? At what prevalence?
35-50% of farms
0-50% prevalence on farms
CODD clinical appearance and grades?
Ulcerative or proliferative lesion starting at coronary band
Progressive under-running of hoof wall downwards
Frequently results in sloughing of entire foot horn capsule
Very painful
Grade 1 - coronary band lesion only
Grade 2 - <50% horn capsule separated
Grade 3 - 50-100% hoof capsule off
Grade 4 - healing but still active lesion present
Grade 5 - healed
What causes the most severe lameness in sheep?
CODD
Extensive damage to foot even down to bone
CODD aetiology?
Treponemes strongly associated - T.medium-like/phagedenis-like/pedis
D nodosus and F necrophorum also found but unknown role
Risk factors for CODD?
Seasonal trend late summer/early autumn
Large flock size
Lowland pasture, lush pasture, poached pasture
Sheep with footrot
Dairy cattle in close proximity
Bought in sheep
Ruminant GI tract, direct contact and foot trimming equipment = infection reservoirs
CODD diagnosis and treatment? Control?
Diagnosis normally visual (lameness and lesion score) Responds to antibiotics LA amoxicillin 71% cure rate Often require repeated injections Macrolides licensed in sheep Formalin/copper sulphate footbaths Topical tetracycline
Control:
- no vaccine and host immunity not protective
- regular footbathing
- improve farm hygiene
- don’t trim infectious sheep lesions
- flock biosecurity: purchase from known sources/health status, isolate lame sheep
What is the 5 point plan for lameness in sheep?
- Vaccinate twice yearly - footvax
- Treat lame sheep quickly
- Biosecurity
- Environmental challenge
- Cull chronically lame sheep
What is footvax? How well does it work? How to use? When?
Footrot vaccine - treats and prevents
70-100% cure rates
60-100% protection rates
May also have small protection against CODD
Multivalent vaccine containing multiple D nodosus strains
Oily adjuvants - site lumps
Don’t use prior to shearing or lambing
Don’t give treated sheep moxidectin 1%
Initial vaccination - 2 doses 5-6 weeks apart
6 monthly booster at risk periods - post scanning (housing) and post shearing in summer
How long to isolate a sheep with footrot/CODD?
3-4 weeks
When to cull lame sheep?
After 2-3 cases of lameness
What is white line disease? What can develop?
No infection just separation of sole from wall - can carefully pare out area of separation
Doesn’t cause lameness unless sensitive tissue affected - impaction with stones, mud etc
Can develop abscesses - heat, pain, swelling, may burst out at coronary band, pare out if necessary to release pus
Treatment for sheep toe granuloma?
IV regional anaesthesia
Cut back granulation tissue
Cauterise with disbudding iron to stop bleeding and ensure granuloma removed
When are pedal joint abscesses seen? Treatment?
Consequence of white line abscess
Flush and antibiotics?
PTS
Digit amputation?
How to do a sheep digit amputation?
Sedation - xylazine IV regional anaesthesia or ring block around foot - procaine Clip, clean and prepare foot Antibiotics, NSAIDs Disarticulate between P1 and P2 Bandage foot Change after 3-4 days
What is the problem with trimming lame sheep feet?
Delays healing
May spread disease to hands and clippers
Studies showed treating alone with antibiotics better - foot shape will return to normal by self
So trimming and topical treatment not recommended for footrot
What to do with overgrown sheep feet e.g. after housing?
Likely to self correct Only careful cosmetic trim Don't over trim - causes granulomas Don't cause bleeding Don't trim if infectious foot lameness!
What can cause post dipping lameness in sheep? What happens?
Erysipelothrix rhusiopathie Number of sheep 1 week post dipping Lame, swelling above coronary band Then progresses to other joints Prompt treatment with penicillin Clean dipper tank
Clinical signs of strawberry footrot in sheep? What causes it? Treatment?
Proliferative scab lesions of distal limbs
Orf dermatophilus
Topical antibiotics and move to dry fields
Types of arthritis in sheep?
Infectious arthritis - neonatal (strep dysglactiae), tick pyaemia (staph aureus), E rhusiopathie
Non infectious arthritis - degenerative joint disease, elbows of adult sheep, unknown aetiology
What type of virus is orf? Clinical signs? Consequences?
Parapox virus - zoonotic Vesicular/proliferative scabby lesions - mouth/head and teats Lambs but can affect ewes esp teats 4-6 week duration Painful - Interferes with suckling/eating - Teat lesions - predisposes to mastitis - Poor growth - Death
How is orf spread?
Spread by contact
Damage to skin and mouth allows virus in - rough grazing/feed esp thistles
Virus doesn’t survive over winter outside but scabs remain infective for long periods in dry conditions
Control of orf?
Isolate clinical cases - disinfect feeding bottles etc
Thorough cleaning and disinfection - steam cleaning (heat sensitive), trigene
No treatment - antibiotics for secondary infection
Vaccine only for infected farms (live and can cause disease, vaccine scabs are infectious, don’t use indoors as will contaminate housing)
What causes sheep scab? Transmission?
Psoroptes ovis - allergic reaction
Spread by direct contact or infected scab fomites material on fence posts etc
Clinical signs of sheep scab?
Kicking, scratching
Wool loss, ragged fleece, moist yellow appearance
Flank/dorsum/whole sheep
Progressively distressed, stop eating, weight loss, seizures, death
Sheep scab diagnosis?
Choose itchiest sheep with wool loss
Edge of exudative lesions - wool pluck (seal in bag), skin scrape (put in container)
Warm sample
If negative sample again
ELISA - detects early stages, good se and sp
Sheep scab treatment?
Must consider re-infection as survive off host 17-19 days
Must treat all sheep
Dexamethasone for severely affected sheep
Improvement in 2 weeks
Organosulphate dip - must do correctly to be effective, 1 minute in dip, do not use showers
Ivermectin - 2 doses 7 days apart, must move to clean grazing after first dose
Doramectin - 1 dose, must move to clean grazing after first dose
Moxidectin 1% - 2 doses 10 days apart, don’t need to move, don’t use if had footvax
Moxidectin 2% - 1 dose, don’t need to move, difficult to administer
Sheep scab prevention?
Biosecurity
Observation not enough as 7-8 weeks before see clinical signs
Treat all bought in sheep
Double fencing
Disinfection of vehicles and equipment esp shearers and scanners
How does Chorioptes bovis affect sheep? Diagnosis and treatment?
Ventral abdomen, scrotum
Pruritis, infertility
Skin scrape
Organophosphate dips
Bovicola ovis? - Appearance? Favourable environment? Clinical signs? Problems? Diagnosis? Treatment?
Small pale red brown louse Highly host specific (sheep) Permanent parasite Spread by direct contact Chew at skin and coat - feed on skin debris and wool Like warm dark environment, not wet Shearing and rainfall reduces risk Pruritis, fleece loss Hypersensitivity and irritation Part fleece on back and flanks and look for clumps of lice Treat worst affected Synthetic pyrethroid pour ons - resistance concerns Plunge dip, diazinon, OP dip
How can scrapie affect sheep skin?
Usually neurological but can present as primary skin disease
Pruritis
Notifiable
When is fly strike seen in sheep? Cause?
May to October
Lucilia sericata - lay eggs in fleece, larvae hatch 12h later, proteolytic enzymes and mouth hooks
Damage skinAttract other flies
Clinical signs of fly strike in sheep?
Wounds Separate Depressed Foot lesions Toxaemia Death
Risk factors for fly strike in sheep?
Temperature - eggs need 10C to develop Humidity >65% - rainfall Shearing and fleece length Faecal soiling - lush grass/worms, tail docking Carcasses on farm
Treatment of fly strike in sheep?
Early is best
Kill maggots - synthetic pyrethroid pour ons, deltamethrin
Clean woundsSupportive - antibiotics, NSAIDs, fluids
House
Address risk factors
Where does Staph aureus usually affect the skin in sheep? Transmission? Treatment?
Peri-orbital eczema
Spread by contact, feeding troughs
Course of penicillin injections
What does Dermatophilus congolensis cause in sheep? Clinical signs? Treatment?
'Lumpy wool' Associated with wet conditions esp after shearing Thin wooled breeds Crusty lesions with wool loss Pruritic Risk for fly strike Treat with penicillin 3-5 days
What causes caseous lymphadenitis in sheep? Treatment? Spread?
Corynebacterium pseudotuberculosis
Affects lymph nodes, esp parotid
Abscesses - antibiotics can’t penetrate so no effective treatment
Spread by close contact, fomites (shearing), resp spread (mediastinal LN abscessed rupture into airway)
Control of caseous lymphadenitis in sheep?
Infected flock: Test and cull affected (culture, ELISA), hygiene of shearing, vaccination
Biosecurity - disease monitoring schemes, isolate and test bought in sheep
Which plant can cause photosensitisation of sheep?
St John’s wort
Causes of abnormal wool fibres?
Border disease - hairy shakers
Copper deficiency of growing lambs
What causes tick borne fever in sheep? Clinical signs?
Anaplasma phagocytophila
Seen in tick areas upland
Profound immunosuppression:
- secondary infections
- fever: spermatogenesis infertility of rams, abortion of ewes
- Predisposed to other diseases
Do become immune
Bought in animals and new lambs most susceptible (no previous exposure)
Control:
- treat with sheep pyrethroid pour ons before entering tick area
- avoid introducing naive sheep when pregnant or at tupping time
What causes tick pyaemia in lambs? Clinical signs?
Staph aureus
Polyarthritis/joint ill
Immunosuppression
Spinal abscesses/joint abscesses
What causes louping ill of sheep? Clinical signs? Prevention?
Flavivirus transmitted by ticks
Non suppurative meningoencephomyelitis
Varying severity - incoordination to seizures and death
Variable signs - head pressing, trembling/tremors, nystagmus, lip twitching, ‘louping gait’
Most infections are slight and give immunity
Often young stock bought in - immunologically naive
Protective immunity in colostrum, vaccine, tick control, grazing management
Zoonotic
Causes of a low scanning % in a flock?
Season
Infectious infertility - toxoplasma, border disease
Ewe - BCS, age, disease
Ram - age, disease, number, fertility
What sheep health schemes are there by the Scottish Rural University College?
Maedi visna (MV)/Caprine Arthritis Encephalitis (CAE) accreditation scheme
Enzootic abortion of ewes (EAE) accreditation
Scrapie genotyping
Scrapie monitoring sheme
Caseous lymphadenitis (CLA)
Johne’s risk assessment
Causes of sudden death of neonatal lambs?
Birth trauma (rib fractures, dystocia) Starvation Hypothermia Clostridial disease - lamb dysentery, tetanus Meningitis Septicaemia Diarrhoea Watery mouth Intestinal torsion Predators
When to sample lambs to check colostrum Ab transfer?
2-7do
Causes of sudden death in growing lambs?
Clostridial disease - pulpy kidney, brassy, abomasitis, tetanus
Pasteurellosis - B trehalosi, M haemolytica
Urolithiasis
Parasitic gastroenteritis
Fluke
Rumen acidosis
Plant poisoning
Causes of sudden death in adult sheep?
Metabolic disease - hypocalcaemia/magnesaemia
Parasites - fluke, Haemonchus
Plant poisoning - rhododendron, yew, laurel, acorns
Pasteurellosis
Toxaemia - mastitis, metritis
Clostridial disease - struck, blackleg, black’s disease, tetanus
When does plant poisoning of sheep usually occur? Which plants? Clinical signs?
Usually when lack of other food available - starvation, snow etc
Yew, acorn, laurel, rhododendron, laburnum
Sudden death, severe abdominal pain, neurological signs
Which agent causes systemic pasteurellosis in lambs? Clinical signs? Risk factors?
Bibersteinia trehalosi Normal inhabitant of URT Sudden death 6-12mo lambs Change of grazing, weather, concurrent disease Stress of handling/gathering may worsen
What do most clostridial diseases cause? What does it do to cause disease?
Sudden death
Organisms multiply rapidly and produce toxins
Trigger factors for clostridial diseases of sheep?
Changes in environment
Injury/trauma/insult
Endoparasites
Poor hygiene
What type of bacteria are Clostridia? How are they grouped?
Anaerobic gram positive rods Grouped by organ systems: - Enterotoxaemia - Parenchymatous organs (liver and kidney) - Myonecrosis and toxaemia - Neurotropic
Which clostridial disease cause what?
C perfringens
-B: lamb dysentery (enterotoxaemia)
-C: struck (enterotoxaemia)
-D: pulpy kidney (nephrotoxic)
C novyi
-A: big head (rams head wounds, myonecrosis and toxaemia)
-B: black’s disease (hepatotoxic)
-D: bacillary haemoglobinuria (hepato and nephrotoxic)
C septicum
-Braxy (enterotoxaemia)
-Malignant oedema (myonecrosis and toxaemia)
C sordelli - abomasitis
C chauvoei - blackleg (myonecrosis and toxaemia)
C botulinum C - botulism (neurotrophic)
C tetani - tetanus (neurotrophic)
Risk factors and prevention for Clostridial diseases?
Enterotoxaemic and parenchymatous groups: dietary change and fittest animals - prevent with vaccination and avoid sudden diet changes
Myonecrosis and toxaemia: contamination of wounds (lambing, castration/tail docking/injections/fighting wounds) - prevent with vaccination and good hygiene
How do sheep get botulism? Clinical signs?
Pasture contaminated with poultry manure
Flaccid paralysis and death
How do sheep get tetanus? Clinical signs?
Contamination of docking and castration wounds
Spastic paralysis, stiffness, recumbency
Often not sudden death
What causes lamb dysentery? When is it seen? Risk factors? Clinical signs?
C perfringens type B Lambs <3 weeks olf Often fit lambs Overcrowding, hygiene Severe abdominal pain, dysentery, sudden death
What causes pulpy kidney disease? When seen? Clinical sign?
C perfringens type D Most common clostridial disease 4-10 weeks old or finishing lambs 6 months plus Sudden death May see ataxia, opisthotonus
What causes clostridial abomastitis and toxaemia? Risk factor? Clinical signs?
Clostridium sordelli 4-10 weeks old Intensively housed creep fed lambs Sudden death Or bloat due to displaced distended abomasum
When to vaccinate against Clostridia in sheep?
4 weeks before lambing to also protect lamb via colostrum
Then lambs from 3 weeks
What causes anthrax? What does it cause in sheep?
Bacillus anthracis
Sudden death
Rare in sheep but don’t rule out
Notifiable
Clinical signs of FMD in sheep?
Lameness
Blisters on tongue
Fever
Not usually fatal (but economic impact)
How is bluetongue spread? Mortality rate? Clinical signs?
Culicoides imicola Up to 70% mortality Fever Swelling of head and neck Lameness Mouth ulceration Drooling Haemorrhages of skin Respiratory probelms
What are prion diseases? Spread?
Causes abnormal protein to accumulate in brain causing neurological dysfunction
Spreads mother to offspring prenatally and via colostrum and milk
And also horizontally via birth fluids, placenta
Clinical signs of scrapie? Incubation period
Progressive, fatal neurological disease Long incubation period: 2-5 years Single animals Altered mental state Excitable, nervous, depressed, aggressive Tremors, ataxia, recumbency Pruritis, rubbing, scratching Weight loss Death
Clinical signs of diffuse cerebrum being affected in sheep?
Altered mental state - depressed, hyper excitable, disorientated
Blindness
Seizures
Opisthotonus - recumbent, extended front legs, flexed hind legs
Examples of conditions affecting diffuse cerebrum in sheep?
Bacterial meningitis
Cerebrocortical necrosis
Pregnancy toxaemia
Clinical signs of local cerebrum being affected in sheep?
Contralateral blindness
Circling
Proprioceptive deficits
Examples of conditions affecting local cerebrum in sheep?
GID cysts (Coenuris cerebrally, Taenia multiceps)
Brain abscesses
Trauma
Clinical signs of cerebellum being affected in sheep?
Altered head carriage Balance - ataxia not weakness, wide-based stance Dysmetria - high stepping Intention tremor Nystagmus
Examples of conditions affecting the cerebellum in sheep?
Not common
Congenital - cerebellar hypoplasia
Border disease hairy shaker - cerebellar hypoplasia
Poss abscess (rare)
Clinical signs of the vestibular disease in sheep?
Head tilt to affected side Loss of balance Circling Falling/rolling to one side Horizontal nystagmus Aural discharge Can get facial paralysis
Examples of conditions affecting the vestibular system in sheep?
Middle ear infection
Unilateral facial nerve paralysis - runs close to middle ear
Clinical signs of the brainstem being affected in sheep?
Depression (because of ARAS) Multiple cranial nerve deficits due to brainstem nuclei - esp V, VII, VIII, Ipsilateral hemiparesis (motor tracts passing through)
What key condition affects the brainstem in sheep?
Listeriosis
Clinical signs of conditions affecting the spinal cord in sheep?
No signs of central disease Depends on site of spinal cord Tetra/paraparesis Proprioceptive deficits Skin sensation Pain Pedal and other spinal reflexes
Examples of conditions affecting the spinal cord in sheep?
Spinal abscess - joint ill tick pyaemia
Wobblers syndrome - texels
Trauma
Congenital abnormality
Common neurological problems in young lambs 0-3mo? Main signs?
Border disease (tremors, hairy shakers)
Congenital swayback (ataxia) - copper deficiency
Drunken lamb syndrome (ataxia, depression)
Lamb nephrosis (ataxia, depression)
Bacterial meningitis (collapsed)
Tetanus
Trauma accident
Spinal abscess (joint ill)
Listeriosis - circling, facial nerve paralysis
Louping ill
Treatment of spinal abscess from joint ill SD in lambs?
1mg/kg dexamethasone
Penicillin for 5 days at least
Common neurological problems of lambs over 3mo?
Cerebro-cortical necrosis (CCN) Listeriosis Gid Louping ill (tick area) Trauma accident
What causes cerebro-cortical necrosis (CCN) in lambs? When affected?
Vitamin B1 deficiency (thiamine)
Acute onset in growing lambs (6-12mo)
Sporadic but can get outbreaks
History of diet change or worming
Clinical signs of cerebro-cortical necrosis (CCN) in lambs?
Vary depending on progression of disease Dull Disorientate Blind Tremors Recumbency Opisthotonus Convulsions
Treatment for cerebro-cortical necrosis (CCN) in lambs?
Vitamin B1 IV (slowly) Vitamin B1 IM every 12 hours For 3 days House quietly Vision should return in 5-7d
What causes listeriosis of sheep? Age affected? What part of brain does it reach?
Listeria monocytogenes
Associated with feeding poorly preserved silage, soil contaminated (mouldy)
18-24mo common - changing molar teeth allowing buccal tissue infection
Ascending infection to brainstem
Clinical signs of Listeriosis in sheep?
Encephalitis, septicaemia
Anorexia
Depression
Unilateral hemiparesis
Trigeminal nerve paralysis - salivation, food impacted in cheek
Facial nerve paralysis - drooped ear, lowered eyelid, deviated muzzle, loss of blink
Abortion (1-2 weeks after feeding poorly preserved/soil contaminated/mouldy silage)
Diagnosis of Listeria in sheep?
Clinical signs
CSF tap
PM
Treatment for Listeria in sheep?
Good if caught early
Gold standard for 75kg ewe:
- 6g benzylpenicillin IV
- 20ml procaine penicillin IM (divided sites, one dose on day of scam)
-1ml/kg dexamethasone IV
- 5ml procaine penicillin daily for 5 days
Supportive care
Remove silage
Septicaemic listeriosis at lambing - hopeless prognosis
What causes ‘Gid’ in sheep?
Taenia multiceps
Eggs ingested by sheep
Develop in brain cerebrum and cerebellum (coenuris cerebralis)
Dog primary host
Clinical signs of Gid in sheep?
Gradual onset Circling Contralateral blindness Head tilt Skull softening
Treatment of Gid in sheep?
Surgically remove cysts
Good prognosis if cerebral location
Poor prognosis if cerebellar location
Which agents can cause otitis media causing vestibular disease?
Pasteurella spp
Streptococcus
T pyogenes
Common neurological problems of adult sheep?
Cervical sub-luxation (paresis, rams fighting) Gid cyst Listeriosis Brain abscess Louping ill Trauma accident Pregnancy toxaemia Hypocalcaemia Hypomagnesaemia Wobbler - texels Scrapie
What is classical scrapie?
Infectious neurological disease of sheep
Fatal, chronic, progressive brain disease of sheep
TSE, prion disease
How is atypical scrapie different to classical?
Very rare
Non infectious, sporadic
What is involved in the statutory scrapie control?
TSE testing scheme - annually, fallen and slaughtered stock and from infected flocks/herds
TSE feed controls - e.g. illegal to feed animal protein to ruminants, and feeding of processed animal protein to all farmed animals
SRM controls at abattoirs - specified risk material removed from sheep >6mo and incinerated (brain, spinal cord, spleen)
Private scrapie controls?
SRUC
Scrapie monitoring scheme - annual flock inspection, samples and test fallen stock
Scrapie genotyping scheme - breeding stock, checks for susceptibility to disease
Causes of thin ewes?
Teeth/oral lesions
Poor nutrition - hill ewes over winter, late pregnant ewes, inadequate grazing, poor forage quality
Chronic disease - respiratory, alimentary
Economic impacts of thin ewes?
Pre-tupping - reduced ovulation so less lambs
Low lamb birth weights
Pregnancy toxaemia and poor colostrum quality
Low milk production so poor lamb growth
Ewe deaths
How to age sheep using incisors?
8 incisors Lamb - all small 1 year - centre pair tall 2 years - 2 centre pairs tall 3 years - 3 centre pairs tall 4 years - all tall
Causes of adult sheep molar problems?
Ageing Periodontal disease - bacteria - malocclusion - diet - uneven wear, feeding of root crops, mineral imbalances
Causes of infections/abscesses/discharge of the mouth of adult sheep?
Necrotic stomatitis - F necrophorum
Wooden tongue - Actinobacillus lignerisei
Lumpy jaw - Actinomycosis bovis
Caseous lymphadenitis
History, clinical signs and prognosis of pharyngeal trauma with dosing guns in adult sheep?
Common!
History: few days/weeks after drenching, number of sheep affected
Dull, depressed, inappetent, weight loss
Halitosis, pain, cellulitis
Poor prognosis - euthanasia, penicillin prolonged courses
Common respiratory diseases of adult sheep?
Laryngeal chondritis Jaagsiekte (OPA) Maedi visna Chronic suppurative pneumonia Mannheimia haemolytica
What is laryngeal chondritis of adult sheep? Breeds/sex prone? Clinical sign?
Abscessation of arytenoid cartilages
Common in Beltex and texels
Rams more common
Loud inspiratory dyspnoea
Treatment for laryngeal chondritis of adult sheep?
Early
Corticosteroids and broad spectrum LA antibiotics
Temporary tracheostomy tube
May not recover/may reoccur
What causes Jaagsiekte/Ovine Pulmonary Adenocarcinoma (OPA)? What does it cause? Which gene is important? What does it target?
Jaagsiekte Sheep Retrovirus (JSRV)
Progressive and fatal pulmonary carcinoma
Oncogenic (env gene is the oncogene)
Overproduction of type II pneumocytes -> overproduction of surfactant
Chronic wasting disease
Spread of OPA? Incubation period? Clinical signs?
Spread via lung fluids and aerosols Long incubation of 2-4y Sudden death Weight loss Increased respiratory effort Exercise intolerance Panting
Diagnosis of OPA? Treatment?
Clinical signs Crackles and wheezing lung sounds Ultrasound - lung consolidation Wheelbarrow test - do quick and stop as soon as fluid appears as distressing for sheep, PTS if +ve PM for definitive No treatment - PTS
Control of OPA?
Biosecurity - buy from known history farms, double fencing, closed flocks
Cull thin sheep/resp signs
Don’t keep offspring for breeding
Reduce close contact housing
Consider outdoor lambing
Vaccine has poor immune response
No reliable test to enable test and cull/testing of bought in
What type of virus causes Maedi visna? What forms of the disease are there? Pathology?
Small Ruminant Lentivirus (retrovirus) - slow progressive disease
Maedi = chronic respiratory disease, can also cause chronic mastitis and arthritis
Visna = neurological signs
Pathology:
- Infects monocytes
- Progressive lymphoid infiltration and smooth muscle hyperplasia in lungs
Route of infection of maedi visna? Incubation period?
Infected when young from mother’s milk/colostrum, respiratory route
Incubation period is several years
Clinical signs >2y, usually 4-5
Clinical signs of the respiratory form of Maedi Visna?
Weight loss
Increased respiratory effort
Exercise intolerance
Clinical signs of the neurological form of Maedi Visna?
Less common
Weight loss
Abnormal gait, ataxia, incoordination, paralysis
Circling, head tremor etc
Control for Maedi Visna in sheep?
Cull
Don’t breed from their offspring
Stocking rates, housing
Difficult as by the time clinical signs seen, 50% may be infected
Test and cull/create separate flocks
Virus latent in genome and avoids immune system so no vaccine
Buy from MV accredited stock
Do sheep develop immunity to fluke?
No
What climate do fluke like?
Warm, wet
Fasciola hepatica life cycle?
Eggs shed by sheep/cow Develop into miracidia Miracidia must swim and find mud snail by 24h after hatching from egg or dies! Cercariae released from snails Encyst on grass as metacercariae Metacercariae eaten by sheep/cow
Why does rain increase fluke?
Increases snail habitats
Allows development of fluke eggs
Miracidia can find snails
Dispersal of cercariae from snails
What temperatures are needed for fluke development outside the host?
> 10C for miracidia to develop in egg
>15C for eggs to hatch and multiplication in snails
When can fluke cause disease in sheep?
Summer infection of snails: disease in sheep in Autumn
Winter infection of snails: disease in sheep in summer
When is acute fluke acute disease seen? Which stage of the parasite causes disease? Clinical signs?
2-6 weeks after ingestion of very large numbers of metacercariae Sept-Dec Severe haemorrhage due to migration of immature stages through the liver Sudden death Weakness Pale Dyspnoea/tachypnoea Tachycardia
When is subacute fluke acute disease seen? Which stage of the parasite causes disease? Clinical signs?
Metacercariae ingested over longer time than acute
Reach bile ducts, haemorrhage to liver en route
Late Autumn onwards
Haemorrhage anaemia
Hypoalbuminaemia
Weight loss
Enlarged liver
Submandibular and facial oedema
Secondary clostridial infection - black’s disease
Common clinical presentation in UK
When is chronic fluke acute disease seen? Which stage of the parasite causes disease? Clinical signs?
Late winter/early spring 4-5 months post ingestion Jan-March Hepatic fibrosis and cholangitis Hypoalbuminaemia Anaemia Weight loss Submandibular oedema
Diagnosis of fluke in sheep?
History and clinical signs
FEC - low but often presence
Haematology - hypo chromic microcytic anaemia, eosinophilia
Biochemistry - AST, GLDH, GGT 13d post infection, hypoalbuminaemia, hyperglobulinaemia
ELISA
PM
Abattoir returns
When will fluke egg counts, serum ELISA antibody and coproantigen be present to diagnose fluke?
Fluke egg count - 12 weeks post infection, fluctuates
Serum ELISA antibody - from 3 weeks post infection but only indicates exposure not whether active infection (good for monitoring naive animals e.g. lambs)
Coproantigen - 8-10 weeks (2-3 weeks before fluke eggs seen), drops quickly after treatment so is used as a drench test
Treatment for fluke?
Triclabendazole - kills all stages but resistance probem Treat and move to low risk pasture Closantel Nitroxynil Oxyclozanide Albendazole
Control of fluke?
- Avoid (reduce stocking density in autumn, assess farm known risk areas e.g. drain wet fields, biosecurity, closantel for bought in animals)
- Monitor (serum ELISA, coproantigen, FEC, forecasting to predict high risk years, PM sudden deaths)
- Targeted drug treatments
When to dose for fluke?
Autumn against immature stages (TCBZ)
Winter immature and adults (Close/Nitrox)
Late spring remove all adults (albendazole)
High risk year/farm:
- extra dose in November for immature (TCBZ)
- extra dose in June for winter infection of snails (TCBZ)
How to prevent flukicide resistance?
Rotational use of drugs - use 3 causes throughout year
Only use triclabendazole when necessary (autumn)
Spring dose against adults important to prevent egg output and summer infection of snails
Quarantine drenching - closantel/nitoxynil
Test for resistance to TCBZ - composite faecal egg count reduction test
What causes Johne’s disease? Clinical signs in sheep? Strains?
Mycobacterium avian paratuberculosis Non specific clinical signs Weight loss Anaemia Bottle jaw High parasite burdens Cattle and sheep strains - may transmit between
Characteristics of Mycobacterium avium paratuberculosis?
Can survive for many months on pasture
Shed in faeces (milk)
Oral route (in utero and colostrum but less important)
At what age is Johne’s typically seen in sheep?
3-4yo
Where does MAP replicate? How does it cause disease?
In GI lymph nodes and gut
Cellular infiltration, thickening of intestines
Malabsorption and protein losing enteropathy
Hypoalbuminaemia
Diagnosis of Johne’s disease in sheep?
Difficult in live animals -faecal smear for acid fast organisms -serology - low se, good sp -low serum albumin -faecal culture SRUC sheep: MAP culture+PCR PM - histopath ileocaecal junction and enlarged distal mesenteric lymph nodes
Control of Johne’s disease?
No treatment Don't graze sheep and goats with cattle Low stocking rates Use plenty of bedding and dag ewes if necessary Cull suspected/confirmed cases asap DOn't keep offspring of infected animals Provide mains water from clean troughs Wean lambs onto grass not grazed by adult sheep this year
By how much does the Johne’s vaccine reduce shedding and numbers of clinical cases?
50%
What is pink eye in sheep? Cause? Risk factors?
Ovien Infectious Keratoconjunctivitis
Mycoplasma conjunctivae
Mixing of sheep, tupping time or feeding
Treatment for pink eye (OIKC) of sheep?
Early cases respond better Isolate affected sheep Look at risk factors for close contact LA oxytet IM of those affected Plus topical antibiotics
What causes anterior uveitis/silage eye in sheep?
Listeria monocytogenes
Associated with feeding baled silage in ring feeders
Clinical signs and treatment for anterior uveitis/silage eye in sheep?
Blephorospasm Cloudiness of cornea Swollen, folded iris Material in front of eye chamber Sub-conjunctival oxytet and dexamethasone Systemic penicillin Remove source
At what level is abortion in a sheep flock a problem?
> 2%
Main 4 causes of abortion in sheep? Others?
Chlamydophila abortus (Enzootic abortion)
Toxoplasma
Campylobacter foetus foetus (C jejuni)
Salmonella abortus ovis
Others:
- Border disease virus
- Listeria monocytogenes
- E.coli
- Tickbourne fever
- Coxiella burnetti (Q fever
- Yersinia spp
- Fungi
- Trueperella pyogenes
- Bluetongue
Enzootic abortion in sheep: Aetiology? Features of agent? Zoonotic? Sources and routes of infection?
Chlamydia abortus:
- gram negative cocci
- intracellular reproductive stage
- extracellular infectious phase
Zoonotic to pregnant women and immonocomprised people
Sources of infection:
- aborting ewes are main sources: discharged products of abortion heavily contaminated and viable for several days
- carrier ewes less commonly: may or may not abort, shed at lambing +/- at oestrus
Route of infection:
- oral
- close contact at lambing facilitates spread
Outcomes of exposure to Chlamydia abortus in sheep?
- Exposure of pregnant ewe:
- if >90d pregnant, may abort
- if <90d pregnant, may abort after 90d or may become latently infected by harbouring agent in reproduction tract and abort at next pregnancy - Exposure of non pregnant ewe:
- becomes latently infected harbouring infection in reproduction tract and aborts at following lambing season - Ewe lamb born to infected ewes:
- can become infected and abort at their first lambing - Exposure of a ewe who already aborted from infection:
- most ewes become immune and will not abort again
- some will become carriers and shed at oestrus and lambing
What is the abortion pattern seen with Chlamydia abortus when newly introduced to a flock by latently infected replacement ewes?
Relatively low levels of abortion in first year
Abortion storms of 30% in the following year
Then endemically infected flocks have abortion rate of 5-10%
Pathology caused by Chlamydia abortus in sheep?
After 90d bacteria replicate in trophoblastic epithelial cells
Severe placentitis is with thickening and necrosis
Placentitis: inflammation of placenta affects transport nutrients and hormone production -> death or damage to lamb
Inflammation of lamb’s internal organs
Clinical signs of Chlamydia abortus in sheep?
Abortion after 90d of pregnancy, often in last month
Death of lambs or birth of weak lambs or birth of one live and one dead
Ewes vaginal discharge couple days
Rarely sheep are ill, occasionally metritis (can be fatal)
Diagnosis of Chlamydia abortus in sheep?
Diagnosis:
- abortion of well preserved lambs in late pregnancy
- submit aborted lamb’s placenta to lab
- gross Pathology: necrotic placentitis
- modified Ziehl Nielson stain: placenta, vaginal discharges or fetus to identify organsim
- culture techniques
- PCR available
- if no abortive material can test vaginal discharges, serology on ewes (care with interpretation, paired serology is best)
Control of enzootic abortion (chlamydia abortus) in sheep?
During an outbreak 1) Stop spread of infection: - burn abortion material and bedding - clean and disinfect pens - isolate aborted ewes 2) Reduce further abortions: - treat remainder of flock with killed inactivated vaccine - or treat all ewes yet to lamb (>90 days) with 20mg/kg oxytetracycline long acting and repeat in 2 weeks The year following an outbreak: - vaccinate all ewes pretupping - if consider there is risk of ewes being infected from previous year, it is acceptable to repeat oxytetracycline injections the year following an outbreak (not acceptable after that)
Also:
- clean flock: don’t buy in, buy EAE accredited sheep SRUC health scheme, breed own replacements
Toxoplasma gondii in sheep: Definitive host? Life cycle?
Definitive host = cats
Reservoir for cats is wildlife
Cats shed millions of oocysts in faeces and then become immune
Oocysts contaminate sheep feed and water - very resistant (>500d)
Sheep ingest oocysts from pasture, bedding, feed or water etc contaminated by cat faeces
What are the possible outcomes of a sheep toxoplasma infection?
- Non pregnant when exposed: develop immunity
- Early pregnancy:
- foetal resorption (ewes will present as barren)
= important cause of low scanning % - Mid pregnancy:
- foetal death
- foetal retardation
- mummification - Late pregnancy:
- abortion of freshly dead lambs
- weak lambs with high mortality rate
- live and immune lambs
- (depends on lamb and placenta’s ability to deal with infection)
Aborted ewes become immune
In endemically infected flocks often see mainly abortion in younger ewes
Diagnosis of Toxoplasma in sheep?
Submit foetus placenta, or paired blood sample ewe for serology
Gross pathology of Placenta: frosted strawberries cotyledons
Histopathology of foetus and placenta
Immunofluorescent
Antibody test of Toxoplasma antigen in placenta
PCR
Serology
Control of Toxoplasma in sheep?
Biosecurity: - Control cat population - Control rodents - Secure feed stores to prevent access Vaccination: - Toxovax = live attenuated strain, undergoes limited multiplication in host - Given at least 3 weeks prior to tupping - Not in pregnant animals - Booster as data sheets
Zoonotic potential of Toxoplasma?
Particularly immunosuppressed people and pregnant women
From undercooked meat, raw sheep milk, cat faeces, lambing
Salmonella abortus ovis in sheep: Sources of infection? What is seen? Diagnosis?
Sources of infection:
- Apparently, healthy carrier sheep (e.g. bought in sheep)
- birds, rodents, wildlife contaminating feed etc
Outbreaks of abortion in last 1/3 pregnancy (can be abortion storms)
Ewes often systemically ill: metritis following abortion
Diagnosis based on isolation of organism from aborted material:
- foetus and placenta
- foetal stomach
Treatment/control of Salmonella abortus ovis in sheep?
Reduce spread: - Isolate aborting ewes - Burn infected material - Clean and disinfect pens Consider antibiotic treatment: - Sick sheep - Whole flock - Long Acting oxytetracycline, repeat 7-10day - NSAIDs Consider source of infection: - Sheep, biosecurity measures (closed flock, don't mix bought in sheep until after lambing) - Other animals e.g. wildlife reduce exposure - Access to feeds, lambing sheds
Campylobacter fetus fetus in sheep: What happens? Sources of infection?
Abortion in last 6 weeks or weak born lambs, 1-4 weeks post infection Ewes may become ill with metritis Sources of infection: - carrier sheep - contaminated feed or water - aborted material - birds Can occur in storms Very contagious in environment Diagnosis: - smear and culture of placenta, fatal stomach and liver Control: - isolate aborting ewes and dispose of material - broad spectrum antibiotics - no vaccine in UK - risk often to bought in replacements - zoonotic!
Border disease: What is it caused by? Maintenance of infection? Signs? What does disease depend on?
Pestivirus closely related to bovine BVDV and CSF Infection introduced and maintained in flock by PI animals Pregnant <60d: - fetal death (barren) - mummification - abortion - still birth - 50% survive and are normal Pregnant 60-85d: - foetal death - abortion - still birth - hairy shakers: encephalitis (cerebral hypoplasia, ataxia, hypermetria), long limbs - small weak lambs - PI (can look normal) Pregnant >85d: - normal Ab positive lambs Non pregnant: no clinical signs What happens with pregnant ewes depends on: - stage of pregnancy - immuno-competence of foetus - strain and dose of virus
Diagnosis and control of Border Disease in sheep?
Diagnosis:
- clinical signs of hairy shakers
- PM lambs (histology, virus isolation)
- Ab serology from ewes
- Ag PCR from ewes
- test suspect PIs from 3mo for Ag
Control:
- if bought in and diagnosed, don’t breed from entire lamb crop and try to identify PI from the bought in sheep and slaughter her
- if endemic, test whole flock for PI and cull?
- biosecurity: closed flock, test bought in for PIs (virus PCR on serum)
Coxiella burnetti (Q fever): Which animals infected? Spread? Transmission? What does it cause? Diagnosis? Control?
Zoonotic (fever, vom diarrhoea, headache)
Infects many species including arthropods, sheep and goats
Spread in infected placenta/foetus/fluids/milk and urine and faeces, dust
Very resistant in environment
Infection via direct contact and inhalation
Abortion storms, still births, poor lambs
Diagnosis:
- Serology, bacteriology and histopathology of foetus
Control:
- Isolation of infected animals
- Burn contaminated material
- Oxytetracycline injectable
- Pasteurisation of milk
Schmallenberg: Which family of viruses? Transmission? Signs in sheep and cattle? When must infection occur for foetus to be affected? Control?
Bunyaviridae family Transmitted by Culicoides Signs in cattle: - mild disease - diarrhoea, fever, milk drop of 50% - recover quickly in 2-5d Sheep: - no apparent clinical signs - increased return to service - increased barren ewe rate Congenital malformations: - may be born alive or dead - may be >25% abnormal births - bent limbs and fixed joints - twisted neck or spine - domed head - short lower jaw - live 'dummy' - blindness - wobbly - inability to suck - fitting Small window of infection of foetus in sheep: 26-56 days Control: - vaccine but not always available - delay breeding to midge season finished?
What to do if suspect Schmallenberg?
Not notifiable
They will send off samples which are tested for free to check for the virus
What to do if an abortion case in sheep?
Isolate ewe Remove contaminated material and burn Clean and disinfect pens Beware zoonotic risk Take appropriate samples: - foetus and placenta - foetal stomach, foetal fluids, placenta - if foetus and placenta not available, blood sample and vaginal swab from ewe
Which bacteria are involved inPasteurellosis of sheep?
Mannheimia haemolytica
Bibersteinia trehalosi
Transmission of scrapie?
Vertical:
- = mother to offspring in utero
Pseudo-vertical:
- parten to offspring at birth, from infected birth tissues
Horizontal:
- adult to adult/lamb from infected sheep
Contaminated land:
- where infected sheep used to live (decades before)
Iatrogenic:
- needle contamination
What are the 5 important PrP alleles in UK sheep for scrapie? Resistance?
ARR - resistance AHQ - resistance with VRQ ARG - susceptibility ARH - susceptibility with VRQ VRQ - susceptibility
Where to polymorphisms of PRP occur and which are linked to scrapie?
Polymorphisms known at 17 codons
Disease linkage to scrapie at codons 136, 154 and 171
What are the components of the national scrapie plan? What about goats?
Scrapie-free farms:
- Voluntary scheme, aimed to protect currently uninfected farms by increasing level of genetic resistance
- lambs and sheep genotyped at no cost, under condition that those bearing VRQ allele will be culled
Scrapie-infected farms:
- Compulsory scheme known as the Compulsory Scrapie Flocks Scheme (CSFS)
- Compulsory slaughter of entire flock (with later restocking) OR compulsory genotyping of entire flock, followed by culling of all animals encoding VRQ (except ARR/VRQ)
Goats also get scrapie (and BSE): TSE control is by whole herd killing, as there is not significant genetic resistance
What is atypical scrapie?
Characterised by:
- unusual distribution of PrPSc in brain
- High age: mean 6.5 years
- mostly single cases in flocks
