Small Rum 2 Flashcards
Nasal bot flies lifecycle, size and lifecycle
- Similar life cycle to blowflies but uses the nasal passages and sinuses for larval development instead of skin
- Adult is grey in colour, size of a bee
- Grubs are 3cm long with distinctive black banding
Lifecycle - Larvae deposited in nasal passages, sometimes orbits
- Larvae take 1-9 months (longest in winter) to develop then are sneezed out and pupate in the soil
- Adult fly emerges after a month
- 1-2 generations per year
- Over-wintering as 1st instar larvae in sheep
Nasal bot flies clinical signs and treatment
Clinical signs - Irritation and head tossing - Mild discharge - Snoring - Incidental finding in post-mortems - Not economically significant Treatment not warranted – ML drenches and closantel give good control
Pesticide residues what occurs with pesticides, what are the 3 main things they have implications for
- All pesticides break down gradually after application and are diluted as wool grows
○ but all except Mg fluorosilicate and spinosad leave some residue at shearing - These residues have implications for:
○ Environment
○ Trade
○ OHS
Pesticides residues what are the 4 important things to observe
○ Meat and milk withholding periods (WHP)
○ Export slaughter interval (ESI)
○ Wool harvesting interval (WHI)
○ Wool rehandling period
Fleece rot cause pathogenesis and clinical signs
Cause - Pseudomonas aeruginosa, but other bacteria can be involved
Pathogenesis
- Prolonged wetting of the skin and warm temperatures cause bacterial proliferation and production of pyocyanin
Clinical signs
- Small crusts seen but mainly discolouration: blue-green to brown over time, also green, purple, brown, grey
- Shoulder, back, loin most affected
- Self-limiting - last for a week or two and then heals and grows away from the body
Fleece rot significance, which sheep most suceptible, risk period, predisposing factors and what can do to prevent
Significance
- Some stain does not scour (cleaning the wool) and therefore devalues the wool
- BUT MOST IMPORTANTLY
○ Fleece rot is very important predisposing factor in body blowfly strike
- Sheep are most susceptible with 4-6 months’ wool
○ Can penetrate easily but doesn’t dry out as easily
- Risk period is late spring to early autumn – so late summer/autumn shorn sheep most susceptible
- Predisposing factors
○ Merinos more susceptible than British breeds and strong wool > fine wool strains
○ High colour, FD variability, shaggy tip, high suint (like sweat) are associated with fleece rot
- High heritability of susceptibility within flocks (h2 ~ 0.4) -> can cull successfully
Fleece rot treatment/prevention and the 4 key points
Treatment/Prevention
- No treatment, but consider fly prophylaxis
- Look for bloodlines with active policy to select against fleece rot – difficult to do in low rainfall areas
- Cull on fleece rot and undesirable fleece characteristics
- Choose a low-risk time of shearing – but many other factors must be taken into account
KEY POINTS
1. Prolonged wetting in warm conditions
2. Sheep in 4-6 months’ wool
3. Predisposition to flystrike
4. Highly heritable, but must show itself
Dermatophilosis what also called, caused by and clinical signs
- Dermo, lumpy wool, mycotic dermatitis
Cause - by Dermatophilus congolensis
Clinical signs - Ulceration then sloughing and repeat
- Active lesions on wool-producing skin show inflammation leading to exudate which forms a crust and mats the wool fibres, initially at skin level
- Chronic lesions present as scabs or mats of dried exudate grow out with the fleece, few mm to several cm across
- Lesions on non-wooled areas are small plaques <1cm -> ears and face -> important source of infection
- Severe generalised dermo may be seen in young sheep
- Derangement of fleece - matted
Dermatophilosis how common, resistence, what are the 3 things dermo requires to infect
- Very common
- Sheep develop some resistance on exposure -> why dip older sheep last
- Dermo requires:
○ Susceptible sheep + A wetting event + Suitable contact
1. Wetting is needed to release zoospores on carrier animals – events include jetting, dipping, rain
2. Mechanical transfer can commence by ~30 minutes after wetting
3, Close contact is likely to occur at yarding, transport in the rain or dipping
□ DON’T YARD ANIMALS WHEN WET, RAINING OR AFTER DIPPING
Dermatophilosis significance and treatment
Significance
- Can reduce fleece weight by 5% and cause downgrading of cotted wool – weaners / hoggets produce the most valuable wool
- Difficult to shear cleanly
- Unsuitable for pour-on lice control
- Active lesions predispose to fly strike
- Deaths, especially young animals
Treatment
- One dose of long-acting oxytetracycline may be effective in resolving more lesions than would self-cure
- May be useful to stop active lesions in advance of shearing (at least 6 weeks) or in severely affected young animals - otherwise not done as will generally self-cure
Dermatophilosis prevention and 5 key points
Prevention
- Avoid prolonged contact events when sheep are wet – especially young sheep
- Use zinc sulphate (heptahydrate) in dip or jet fluid
- Breeding for resistance is not very useful (h2 ~ 0.1-0.15)
Key points
1. Effects on FW, $/kg and ability to be shorn
2. Mainly young sheep
3. Susceptibility + wet sheep + close contact
4. Avoid letting these things happen together!
5. ZnS04 in the dip or jet
Strawberry footrot what is it, when common, what age most susceptible and clinical signs
- Dermatophilosis of the legs
- Common in winter with persistent wetting
- Weaners and hoggets most susceptible
Clinical signs - Exudative dermatitis extending from the pasterns dorsally
- Confined generally to haired regions
- Scabs are easily knocked off when walking revealing raw granulating tissue - source of infection
- Lameness
Diagnosis and treatment of strawberry footrot
- Clinical signs and confirmation by Gram stain
- May be able to move sheep to a drier paddock or one with shorter pasture
- Antibiotics may help, but are rarely justified - only if very severe
- Clinical course is 4-6 weeks, prolonged if lesions are continually wet or secondary bacterial infections occur
- Looks like scabby leg - similar pathogenesis and treatment -> prevent excessive wetting
Scabby leg location and what common
- Scabby leg is seen around the pastern, coronet and between the bulbs of the heel
- Secondary infection by Dermatophilus is common, as is flystrike
Scabby mouth what also called, cause, pathogenesis
- Contagious ecthyma, contagious pustular dermatitis, orf, scabby leg
Cause - Caused by a Parapoxvirus
Pathogenesis - Infection requires a break in the epithelium
- Small hyperaemic foci develop within 7 days, vesicle forms and bursts, scabs left in areas other than the oral mucosa
- Lesions and disease usually resolve within 3 weeks
Scabby mouth clinical signs, where present, which month most common, spread of disease and immunity
Clinical signs
- Lesions are seen mostly at the commissures of the lips but also anywhere on the oral mucosa, nasal membranes, ears and teats
- Almost ubiquitous and exists on most farms in Victoria
- Occurs most commonly in summer months, with virus entering through cuts and abrasions associated with dry feed
- Scabby leg is usually seen in winter with persistent wetting and softening of the skin
- Disease can spread quickly when there is a large number of naïve sheep feeding from troughs
- Large quantities of virus are produced in the lesions, which remains infective on pasture and in feed for very long periods
- Immunity following infection (or vaccination) is long lasting (2-3 years)
Scabby mouth/leg diagnosis and significance
Diagnosis
- Via clinical signs
- Looks like strawberry footrot but treated the same - both self-limiting just dry
Significance
- Usually of little consequence with outbreaks in weaners which resolve over several weeks
- May be decreased grazing and therefore weight loss due to painful mouths
- Ewes with teat lesions are reluctant to allow lambs to drink - transmission
Scabby mouth/leg treatment, control and zoonosis
Treatment, control
- There is no treatment and the disease is self-limiting
- Live virulent vaccine
○ Scratched onto skin of axilla
○ The vaccination site of a few sheep should be checked for ‘take’ (reaction)
○ Some shipments require vaccination
Zoonosis
- People can be infected on the hands or leg
- Handling infected sheep and accidental inoculation with vaccine are the most common sources
Actinobacillosis what also called, cause, when main issue, prevalence in herd and clinical signs
- Leather lips
- Actinobacillus lignieresii (causes woody tongue in cows)
- Occasionally causes problems when sheep are on coarse dry feed in late autumn and summer
- <10% affected but occasionally large outbreaks with up to 30% of animals - rare
Clinical signs - Areas affected include the lips, face, nose, lower jaw and lower neck, and rarely the tongue
- Lesions may be superficial or a deep honeycomb of small abscesses beneath the skin, often discharging sinuses with yellow-green pus
Actinobacillosis diagnosis and treatment
- Clinical signs are diagnostic, swabs to confirm
- Most sheep recover
- Can treat with antibiotic (iodides, tetracyclines, erythromycin), provide soft feed
Squamous cell carcinoma how common, location, prevalence and what can be associated with
- Very common on older sheep
- Occur on 2 major exposed areas: vulva, anus, tail and bare mulesed skin (‘rear end’ cancer) and face, planum, lips, and especially the ears
- Prevalence influenced by age: 1% typical but can be >20% SCC in sheep older than 5 years
- SCCs of the perineal region are usually associated with mulesing – trauma to the skin may be a risk factor
Squamous cell carcinoma pathogenesis how grow, what prove to, predisposes to and diagnosis and treatment
Pathogenesis
- Usually start as one of two forms: a hyperkeratotic nodule or a column (cutaneous horn)
- Tumours grow relatively slowly – around 6 months to get to around 5cm – and rarely metastasise remotely
○ Treat if high valuable animal is possible -> removal of tumor
- Very vascular and prone to damage and bleeding
- Predispose to secondary bacterial infection and flystrike
Diagnosis, treatment
- Diagnosis based on clinical signs – most farmers are very familiar with them
- Treatment is seldom worthwhile but some farmers will trim ears to remove tumours (chargeable offense)
○ EUTHANASIA
Squamous cell carcinoma what are options for prevention
- Lower the culling age
- Cut tails at the 3rd coccygeal joint (cover the tip of the vulva) -> don’t cut too short
- Use ‘modified V’ mulesing pattern to leave wool on the tail - better still - DON’T MUSEL
- Provide shade in all paddocks
- Minimise the number of eartag notches etc
Facial ecezma what is it caused by, when present, what prefer, when have outbreaks and where
- Hepatogenous photosensitisation caused by ingestion of the fungal toxin sporodesmin, produced by Pithomyces chartarum
- Fungus is present all year round but requires moist warm conditions to multiply sufficiently – late summer/autumn
○ minimum temps >15oC for 72 hours - predictable -> warnings about storms - annual pastures are less dangerous
- outbreaks in summer/autumn (gippsland)
Facial ecezma clinical signs and how long take to develop
- Signs develop within about 1-3 weeks of toxic insult
- Initially photophobia and pruritis, restlessness, shadeseeking, twitching, shaking of head and ears
- Affected areas rapidly become erythemic and oedematous – swelling of the ears, eyes, intermandibular space, nose
- Nasal discharge and lacrimation
- Serous weeping of the skin as it becomes necrotic and progresses from crusty to black and eventually sloughs leaving areas of raw skin
- Jaundice in more severely affected animals
- Many animals slowly recover but many have permanent liver damage
Facial eczema treatment and prevention
Treatment
- Move animals from source of toxin to safer areas with access to shade
- Put severely affect sheep in sheds and feed low protein diet (give the liver a break)
- After recovery cull all affected sheep
Prevention
- Do spores counts after high risk weather
○ When spore counts are high move sheep to tallest pasture to minimise grazing of lower sward, feed hay
- In NZ, pastures may be treated with fungicides such as thiabendazole
- Zinc can be useful if given before exposure – ZnSO4 in drinking water not as effective as in cattle but ZnO as a slurry every 2 weeks has helped
- Controlled-release capsule (Time Capsule®) available in NZ: 6 weeks’ protection
- In NZ, selection for resistance to facial eczema
○ High heritability: h2 = 0.42
Lupinosis cause, where located, what conditions, what most susceptible
Cause - Hepatic disease caused by the fungus Diaporthe toxica (ex Phomopsis leptostromiformis) which grows on lupin stubbles - MAINLY IN WA AND SA
- Under moist warm conditions the fungus proliferates and produces a stable hepatotoxin
- Affected paddocks are dangerous until fresh growth is treated
- Weaners most susceptible because they eat more stem
Lupinosis clinical signs and diagnosis for the two types
Clinical signs
- Two syndromes
○ Acute: inappetence, depression, lethargy, jaundice, deaths
○ Chronic: weakness, lethargy, loss of condition, stifflegged gait, disorientation
- Abortions, reduced lambing percentage, reduced wool production and tender wool with both syndromes
- Sheep that recover often fail to thrive
Diagnosis
- Diagnosis based on clinical signs, history and PM findings of acute to chronic liver damage
○ Differential diagnosis for acute: caltrop, other plant toxins e.g. Paterson’s Curse, eperythrozoonosis
○ Differential diagnosis for chronic: protein/energy deficiency, parasites, OJD, trace elements
Lupinosis treatment
- Move animals from source of toxin to safer areas with access to shade
- Put severely affected sheep in sheds or paddocks with good shade and feed low-protein diet (e.g. oaten hay)
- Euthanase severely affected sheep
- After recovery cull all affected sheep
Lupinosis prevention 6 options
- Use lupin stubbles efficiently and quickly after harvesting
- Provide two watering points to promote even grazing
- Train sheep with lupin seed
- Once grain falls below 40/sqm remove sheep
- Observe sheep on lupin stubbles as closely as possible
- Check lupin seed before feeding – avoid using if >10% discoloured
Dermal necrosis when most susceptible, location, clinical signs and treatment/prevention
- Recently shorn, fat sheep (<2 weeks), in very hot weather and lack of shade
- Subcutaneous fat on backline heats up
- Hard, black skin after a few days, sloughs, heals over several weeks
- Antibiotics and a fly preventive may be useful
Grass seeds how common an issue, main involved, what affect and mostly problem in which sheep
- Grass seeds are a major problem on some farms - depends on the pasture used
○ Barley grass, spear grass and corkscrew are the major offenders in southern Australia - Can affect lamb growth rates
- Seeds are unsightly and publicly unacceptable in meat cuts – heavy carcase contamination can cause downgrading due to heavy trimming
- Mostly a problem in sheep with long wool
Grass seeds prevention
- Shear before problem grasses set seed
- Young sheep are at greatest risk so keep them out of affected paddocks
- Spray graze
- Renovate pastures to displace problem species - ryegrass, phalaris, clover
List 10 causes of damage to sheep skins
- Over-crutching
- Trucking stain
- Raddle marks
- Grass seeds in the wool and pelt
- Burrs in the wool
- Vaccination puncture sites
- Shearing cuts
- Wool diseases – dermo, fleece rot, lice
- Dog bites
- Handling injuries
Over crutching what is the main affect, raddle (large cradle used to mark sheep) marks how occurs, how to prevent
Over crutching
- Meat buyers often like a wide crutch, but skin is more valuable with a keyhole crutch
- Crutching over a larger area reduces the area of woolly skin and destroys the natural shape of wool on the skin, which may necessitate further trimming
Raddle (large cradle used to mark sheep) marks
- Woolly skins are scoured at body temperature (37°C) and raddle marks may not be removed
- Raddles and stock markers should be kept to an absolute minimum on sheep destined for sale
- Marks should be restricted to the head or top knot only, with the central panel of the skin kept clean
Trucking stains what regulations in place to prevent this and what does it increase the risk of
- Sheep should be yarded for at least 12 hours before transportation, and:
○ Offered only dry feed
○ Offered water, then none for 12 hours (journeys <24 hours)
○ Offered water to at least 4 hours pre-loading for journeys >24 hours
§ But refer to the Standards - This ‘curfew’ minimises soiling of wool on the belly, flanks and/or hind legs
- Trucking stain significantly increases the risk of carcase contamination with Salmonella and E. coli bacteria at slaughter
Burrs on sheep skin how to remove, when cause issue and prevention
- Skins can be deburred, but this involves additional costs and causes damage to some skins
- Hard burrs such as Bathurst and Noogoora burrs cause problems during fleshing
- Prevention involves shearing or selling lambs before burrs appear, and pasture management to eradicate burrs from paddocks where sale sheep are run
Vaccination sites causing skin issues what result in and how to prevent
- Vaccination punctures can leave a small fibrous scar which is a visible blemish in the processed leather, or at worst, subcutaneous adhesions and abscesses
- Sheep should not be vaccinated on the back or shoulder
○ the easiest and most commonly used sites! – better to use the brisket, neck, cheeks or axilla
Sheep and goat mastitis how common and causes
Sheep
How common
- Terminal sires -> up to 5% normal
- First cross - about 2%
- Merino - 1 or 2%
- All breeds - outbreak with up to 20-30% of ewes affected
- Dairy breeds - depends on hygiene/environment
Causes
1. Mannheimia (pasteurella) spp. - most common (not seen in dairy cows)
2. Staphylococcus aureus
- Both can lead to black or blue mastitis
Goats
- Relatively uncommon but same causes
Sheep and goat mastitis what is the worse mastitis type, clinical signs and what does other clinical mastitis lead to
Black mastitis
- Can lead to death quite rapidly
- Almost all ewes culled at end of current lactation
- If retained, half udder non-functional - problem with twins and triplets
- Lambs generally die or are fostered
○ Quality and quantity of milk declines
- Lame, lose weight
Other clinical mastitis
- Less severe, may not result in loss of udder
- Milk quality impact
- Lamb death rate
- Reduced production
