Small ruminants 3 Flashcards
Clinical signs of redgut and post-mortem changes
- Clinical signs -> dead and dying animals with abdominal crisis: abdominal pain, tympany/distention, recumbency
○ Post mortem changes - Most cases 180-360 clockwise torsion of intestines
- Devitalisation of blood vessels supplying the gut - cranial mesenteric artery is the one that is blocked
○ Generally the devitalised section of GIT is distinct from the vitalised area - Bright -> dark red intestinal discolouration from after 1st meter of small intestine through to rectum
Redgut what are the 2 other main differentials and why
○ Other causes of sudden death following feed change
§ Pulpy kidney (unvaccinated lambs)/enterotoxaemia
§ Plant positioning -> nitrate, cyanide, phalaris
Redgut treatment and prevention
○ Immediately removing affected mob from high-risk pastures stop outbreaks
○ Address risk factors by reducing digestibility of diet
§ Providing source of higher fibre of feed amongst the higher digestible pasture -> hay
§ Gradually introduce the animals to the higher digestible pasture
Where is a place that you see a lot of abdominal problem, why and the 3 main abdominal issues
FEEDLOT DISEASES
- SUDDEN DIETARY CHANGES
○ Intensive feeding - from paddock feeding to grain feeding
Main Health Issues
- Abdomen-related:
1. Ruminal acidosis
2. Shy feeders
3. Entertoxaemia/pulpy kidney (overgrowth of C perfringens - IN SUDDEN DEATH LECTURE)
§ Vaccine preventable disease - BOOSTER BEFORE INTENSIVE SYSTEM INTRODUCTION
Ruminal acidosis in sheep pathophysiology and presentation/diagnosis
- Same pathophysiology as in cattle
- Presentation
○ Intermittent inappetence, dullness, recumbency and deaths in late-pregnancy ewes
○ History of: Receiving “on and off” grain ration in paddock
○ Doughy rumen with undigested grain
○ Ruminitis -> painful abdomen
○ Flystrike - diarrhoea leading to flystrike
Diagnosis
○ Rumen pH about 5 -> if >25% have rumen pH <5.5
○ need to consider history and clinical signs
What are some important mob management/prevention strategies for grain overload
§ Reintroduce grain…slowly! - 50g/h/d to build to final ration over 3 weeks (2-3 feeds per week)
® Sheep in feedlot need full ration of 3.5 kg/h/week
□ But these ewes need extra feed to prevent pregnancy toxaemia
□ Add virginiamycin to help protect as feed reintroduced faster?
□ OR use alternate feed -> high fibrous feed
§ Mix batches of feed when changing over
§ When on full ration feed only 2-3 times per week gives all animals time to access feed, avoiding unpredictable, intermittent access by sky feeders
What are some individual management/prevention strategies for grain overload
§ Oral drench several times daily
□ sodium bicarb. 20 g
□ magnesium hydroxide 40 g
§ Penicillin, fluids and supportive care
Entertoxaemia/pulpy kidney what caused by, presentation, differentiation from redgut and prevention
- Clostridium perfringens type D overgrowth due to diets high in soluble carbohydrates
- Presentation
○ Sudden death
○ Abdominal pain
○ Bloating
○ (Diarrhoea in goats)
○ But pathology in intestines, body cavities & brain - HOW DIFFERENTIATE FROM REDGUT
§ Hyperaemia due to general vasculitis - Prevention - Vaccinate in the face of an outbreak & try to reduce concentrate feeding
Shy feeders in feedlot situations what are the 4 main reasons this occurs
- Poor adaptation to feed ○ Behavioural § Not imprinted on feed (or infrastructure) § Small size/Low in social hierarchy ○ Dietary § Not accustomed to diet § Low-grade digestive problems reducing VFI ○ Physical § Insufficient trough or pen space ○ Concurrent disease e.g. § Vitamin E defic, scabby mouth
Shy feeders in feedlot situations diagnosis, management/prevention and what is important to consider
- Diagnosis
○ Poor weight gain/weight loss
○ Atrophic rumen papillae - animal has not eaten for many weeks - Management & Prevention
○ Regularly identify & remove for paddock feeding - important
○ Draft pens by size/age
○ Sufficient space
○ Imprinting!
○ Make sure enough roughage (≥10% w/w of concentrates)
SHY FEEDERS AND ACIDOSIS CAN OCCUR IN THE SAME MOB
What are the 10 general guidelines for inducing animals into feedlots
- Site: good drainage, enough space (pens, troughs, water supply)
○ Water: 10% BW/day (5+ L) - Draft into weight groups
- Pre-treatments:
○ 5 in 1 vaccine, Drench
○ Treat external parasites if needed - Good quality hay if must enter immediately
- Introducing concentrates
○ 2-3 weeks BEFORE entering feedlot
○ Familiarise with feeding equipment
○ Only ad-lib once introduction complete (production) - Roughage: 10-20% of conc. ration
- Remove any sick or diseased sheep or other problems (lame)
- Weigh and redraft to remove lambs not growing
- Follow WHP and ESI of treatments and keep records
- Removal onto pasture
○ Ensure adequate pasture and let out after feeding to avoid gorging
PSI what is it, what situations generally found within and what occurs
LIVE EXPORT - PSI (persistent inappetence, salmonellosis and inanition syndrome)
- Syndrome of sheep on live-export ships leading to increased mortality
- Inappetence increases the risk of sheep being infected by salmonella resulting in clinical salmonellosis or starting to shed the organism
○ Additionally ruminal acidosis can also favour salmonella problems
§ Low pH disrupts normal rumen microflora, allowing salmonella overgrowth
PSI (persistent inappetence, salmonellosis and inanition syndrome) risk factors and management/prevention
- Epidemiology/risk factors
○ Poor adjustment to total ration during pre-export feedlotting
§ If sheep remain inappetant as they start voyage are 3-14 times more likely to develop
○ Dietary upsets and poor adjustment increase inappetence therefore increase risk - Management - BEFORE EMBARKATION
○ Not mixing groups
○ Gradual introduction of feed
○ Managing high risk groups
○ ONCE ON SHIP - move to hospital pen with higher fibre feed
What are the 3 main production areas in terms of weather and what worms are found there
- summer dominant
- Haemonchus contortus
- Tr. Colubriformis - uniform rainfall - heading south (Gippsland)
- Haemonchus contortus - winter rainfall
- Ostertagia (teladorsagia circumcincta), Trichostrongyles
Roundworms of sheep what is the main points of the lifecycle
- Pre-patent period is 17-21 days
- Eggs, LI and L2 susceptible to desiccation, L3 more resilient
- Population ecology - variation in fecundity and rate of development
○ Haemonchus contortus > Trichostrongyles colubriformis > Trichostrongyles vitrinus > Teladorsagia circumcincta - Delay in translation of infection from eggs in faeces to L3 on pasture (>8 weeks), hence infection of sheep
○ Impact of PPR variable
○ Weaning of lambs - getting off before this point at 8 weeks
Winter rainfall area in terms of internal parasites what are 4 main things that occur with L3, contamination and strategic drenches
- Highest availability of L3 in winter - June, July, August
- Late summer/autumn contamination important source of winter peak in availability of L3 - reduce with drench
- Significant over-summer survival of L3 developing from eggs-deposited in spring and early summer (adequate ‘refugia’)
- Strategic summer drenches generally works well (less reliable in wet summers)
In terms of infection and L3 in winter rainfall areas for internal parasites what occurs in summer, autumn, winter and spring
- Summer generally too hot and dry for development of eggs to L3
- Dews and autumn break provide moisture
- Low winter temperature slows development but long survival and short pasture -> max L3/kg herbage
- Spring ideal for development, but longer grass dilutes L3/kg - drop off in numbers
- Rising temp in late spring/summer limits survival of eggs/L1/L2 BUT also locks L3 in faecal pat (can survive)
Internal parasite control programs list 7 things can use concurrently to get the best result
1) test for drench resistance (every 3-4 years)
2) 1 or 2 stragic summer treatments in winter/winter rainfall areas
- > highly effective - SD1 in DEC, SD2 in FEB
3) WEC monitoring to avoid unnecessary treatments
4) quarantine and treatment for introduced sheep - not generally done
5) nutrition
6) grazing management (wet years, high rainfall) - lower risk pastures for weaners
7) breeding for increased immunity - rams selected for low WEC
testing for drench resistance how often done, how
(every 3-4 years)
○ WECRT - worm egg count reduction trail
○ 10 (15) samples per group, 5-8 groups (each drench + control group), best to get lambs at weaning as exposure but not drench yet - IMPORTANT (If used adult sheep -> Change in egg count could be about the ewe’s immune
Lambs -> Closest correlation between egg count and worm burden)
○ Single pre and post drench WEC -> 10-14 days (before PPP - 3 weeks)
WEC monitoring to avoid unnecessary treatments what need to do, when and how often
○ Bulk WEC, 10-20 sheep/mob
○ Before SD1
○ All mobs before SD2 (cut off is 25-50 eggs)
§ Do larval culture/PCR if Haemonchus present
○ Weaners - after autumn break (every 4-6 weeks)
○ Ewes - before lambing (need to pre-lamb drench)
Nutrition for reducing internal parasites what is needed
○ Feed availability and CS target for ewes
○ Growth targets for weaners
○ Feeding protected protein
○ Pasture containing condensed tannis
Grazing management to reduce internal parasite burden what are the 2 main things can do
1) sheep-cattle interchange - sheep benefit the most
2) smart -grazing - low-risk pastures
Sheep-cattle interchange for grazing management with internal parasites how effective, what cattle needed, how often rotate, who benefits the most and why
○ Very effective grazing management strategy
○ Needs cattle to be at least 20% of DSEs
○ Avoid young cattle (T. axei and H. contortus)
○ Initially suggested a 6-monthly rotation in Jan-Jul, but this can be varied (6 weeks min >12 weeks better)
○ Sheep benefit the most
§ Reduces teladorsagia (Ostertagia), haemonchus, trichL3 by >90%
§ Increase GFW by 25% (0.7kg) and Wt gain by 65% (7kg)
§ Decrease TWC by 85% (2160 vs 14800)
○ Can move sheep first and delay moving cattle for 2-3 weeks if sheep pastures too short for cattle
Smart-grazing for grazing management to reduce internal parasites what are the 2 steps within
a. Prepare paddock (nov-mar)
- Graze at 2.5 times stocking rate for 30 days post drench then rotate to another paddock
- After second drench same stocking rate place again onto that paddock for 30 days (PPP)
b. Graze after autumn break on this pasture that should have low worm burden
- Graze the weaners that are most susceptible
Breeding for increased immunity to internal parasites what is involved and which worms work best on
- Selection for low WEC
○ Sheep (rams) are selected using one WEC at 12 months heritability 0.25
○ Worm resistance increases significantly after - 7-10 years
○ Resistance to Trichostrongyles and Haemonchus > teladorsagia (Ostertagia)
○ Decreased contamination gives significant production advantages
Vaccines for internal parasites, what one use, where and why and the intervals for the V1-V6 in lambs
- Barbervax program
- Spring-born lambs in summer rainfall areas (NSW) -> where Haemonchus is common
- V1: 1st vaccination at lamb marking
- V2: 2nd 3-4 weeks later
- V3: 3rd vaccination + drench 3-4 weeks later at weaning (move lambs to a prepared low worm-risk paddock, ideally one not grazes by sheep for 3 months) -> significant advantages found here
○ Need to also do smart grazing technique
-V4: 6 weeks later - V5: 6 weeks later
- V6: 6 weeks later
Ewes vaccine for internal parasites what areas and when give V1-V4
again in the summer rainfall areas V1: 8-9 weeks pre-lambing V2: 4-5 weeks pre-lambing V3 - 1-2 weeks pre-lambing effective drench to control scour worm and early barbers pole V4 lamb marking
Nematophagous fungi what is it 2 main ones, what used for, what is needed and results
fungi that attack nematodes 1) Duddingtonia flagrans ○ Known about since 1930s ○ Decrease larvae on pasture by 50-70% ○ L3 need to be active ○ Need to get fungal spores into the dung at the best time: § Feed 1.5 million spores/50kg sheep daily for 8-12 weeks -> when already feeding supplementary feed § Controlled release capsules 2) BioWorma - new product ○ Just released ○ Not cost-effective for sheep
Efficacy of ML on internal parasites in VIC, QLD/NSW and which best
- VIC -> less resistance found here
- NSW/QLD -> higher resistance to MLs due to worms present in these areas
- Ivermectin -> abamectin -> moxidectin (higher potency and less resistance than ivermectin)
what is the resistance like with BZ and OPS
- BZ - high resistance, combination of BZ/LEV -> less resistance
- Combinations wit OPS are effective (>95% reduction in WEC) on 60-70% farms tested
Anthelmintic Resistance what are the 5 main principles
a. Late detection of the resistance in the population
b. Very slow/negligible ‘reversion’
§ Levamisole generally greater reversion then others
c. Side resistance (within group) is universal
d. Cross-resistance (between groups) is rare
e. Short-acting vs persistent drugs
§ ‘head selection’ (potency) and ‘tail selection’ (persistency - long acting moxidectin, Closantel)
§ Long-acting preparations tend to have a longer tail ( closantel, LA, Mox injection, Mox oral)
Anthelmintic Resistance impacts on the farm what does it depend on
has resistance reduced farm productivity and profitability
○ Generally business as usual for resistance on farms -> effective strategies to prevent this can be profitable
○ Depends on:
§ Region/location (much worse with Haemonchus)
§ Genetics of resistance
§ How well farmer adopts ‘best practice’ - both for worm control and other determinants of farm profitability
Anthelmintic Resistance risk factors what are the 4 main ones
a. Frequent treatments
§ First report in sheep on research farms (Haemonchus)
b. Under-dosing
§ Dosing strategy (average vs heaviest)
§ Under-estimating BWts
§ Low volume drenches - cheaper to ship
§ Goats (rapid metabolism of anthelmintics)
c. Movement of animals
d. Proportion of worm population ‘in refugia’
§ Rapid increase in ML resistance by teladorsagia (Ostertagia) in WA and kangaroo island
□ Assumed to be significantly lower proportion of over-summering larvae
WANT HIGHER REFUGIA
What are the 3 main options to combat low refugia populations
- Crop stubbles and fodder crops
○ Graze with contaminator mobs of known WEC
○ ‘move then treat’ - Delay summer drenches
○ Now suggested for ewes in WA
○ Weaners still get 2-summer drenches - Targeted selective treatments
○ Based on higher body weight/CS, growth rate or lack of anaemia (resilient sheep)
○ For tactical drenches (Haemonchus)
○ Problem with higher labour costs
○ Strategic drenches - what proportion treated
§ Target WEC
§ Set percentage - generally doesn’t work as well
What 3 things need to consider when trying to combat low refugia populations
- Worm ecology and control programs differ markedly between regions
○ Amount and distribution of rainfall
○ Length of growth season - Importance of summer/autumn contamination in winter rainfall areas
- Difference between wool and prime lamb flocks
What population of refugia is needed to delay resistance
○ Need 30% of population to escape treatment to delay resistance
In south east Australia what refugia is present, should you increase contamination and what is important to look for with refugia
- Already ample over-summering (refugia) populations of infective larvae in Victoria
- Deliberately increasing contamination is not appropriate as a general recommendation
○ Needs A LOT more monitoring
○ Increases risk of unacceptable production losses
○ Unlikely to make a big difference if genes for Rx are dominant/semi-dominant - Identify risks of extremely low refugia
○ Drought, crops and previously de-stocked farms
○ Devise and monitor a strategy
Live fluke what losses occurm what drives life cycle and the 2 main types of diseases
- Similar production loss to scour worms
- Breeding season of lymnaeid snail intermediate host drives the life cycle
- Types of disease
○ Acute fluke disease (immatures Dec, Jan) - blood feeders - pale and jaundice - MOST COMMON IN SHEEP
○ Chronic disease (May-Jul) -> bile ducts blockage -> anaemia and bottle jaw - MOST COMMON IN COW
Live fluke what is involved in the control
○ Extent of infestation - most of the farm (irrigated farms or just isolated areas)
1. Isolated areas
□ Fence or don’t graze with young stock
□ WEC before graze area (treat if +ve) and/or treat when remove (max 9 weeks = PPP)
2. If more widespread - treat
□ Feb and Aug (before autumn and spring breeding of snail)
□ Triclabendazole - activity vs 2-4 weeks old
□ Combinations of Closantel with OFZ or ABZ (8w.o)
□ ABZ (14w.o)
Goat and internal parasites what is different
- Few products registered
- Different pharmacokinetics in goats
- Less immune/resilient - frequent treatments
- Rapid selection for resistance in high rainfall areas (Haemonchus)
- FAMACHA can work well in smaller flocks
What are the 5 main causes of diarrhoea in sheep
1. Worm related ○ High WEC/TWC or high larval challenge ○ Hypersensitivity scouring 2. Weaner colitis/enteritis ○ Coccidiosis ○ Campylobacter ○ Yersinosis ○ Often made worse by nematodes, SE/Vitamin E deficiency, M.ovis 3. Adult sheep ○ Yersinosis ○ Salmonellosis ○ OJD 4. Nutritional scouring ○ Lush feed, PRG endophyte, phalaris 5. Neonatal scouring ○ Cryptosporidium, giardia ○ E. coli, rota- and coronavirus
