Lameness in sheep Flashcards
1
Q
Isses regarding lameness in sheep
A
huge economic and welfare
2
Q
Lame sheep, what are your Ddx
A
- foot rot?
- starts as benign ovine interdigital term/ SCALD = no under running hoof wall or sole, no smell, inflammatory between claws
- progresses to virulent = under running hoof and sole - CODD?
MORE severe than footrot, ulcerative lesions start at coronary band. Hoof sloughs off - White line disease
- Toe granuloma (clipping)
- Foot abscess
3
Q
What lesions can appear in association with lameness?
A
- interdigital hyperplasia
- Overgrown or misshaped claws
- FB
- Soil balling
- Granuloma
4
Q
What disease processes are associated with lameness?
A
- Fracture
- Musculature
- Neuro
- Arthritis
MAKE SURE YOU EXAMINE WHOLE LIMB, NOT JUST FOOT!!
5
Q
Benign foot rod/ Interdigital term/ SCALD about
A
- V COMMON
- Widespread in U.K 97% of flocks affected
- can be lesion on own or as part of general foot problem
- often what see first
- inflamed interdigital skin, discharge, exudate, white flaky pasty scum
- NO HORN UNDER RUNNING SEPARATION
- Dichelobacter nodosus
6
Q
BFR/ SCALD/ IDD aetiology
A
- Dichelobacter nodosus (anaerobic)
- considered Fusobacterium necrophorum and it is found in some cases but now thought to just contribute
- damage to skin may predispose to bacterial infection (damp conditions underfoot, frost and/or mechanical damage from long grass, thistles)
- allows various bacteria invade interdigital skin
7
Q
What bacteria causes Benign footrot/ IDD/ scald?
A
Dichelobacter nodosus (anaerobic)
8
Q
Risk factors of footrot
A
both benign and virulent same
DAMP - grass, trough, gates
Mud
Genetics - heritable susceptibility
high stocking
9
Q
Will benign footrot progress?
A
o Lesions can progress to full blown footrot with underrunning (separation) of horn depending on the virulence and dose of the D. nodosus
o The susceptibility of the sheep
o Whether the sheep is treated promptly before separation of the hoof horn occurs
10
Q
Virulent footrot CS
A
- Interdigital dermatitis and lesion plus….
- Progressive under-running of sole of hoof horn starting at medial aspect of sole, progressing laterally due to strains or load of bac on foot
- Grey necrotic pungent smelling horn
11
Q
agent in footrot
A
- Dichelobacter nodosus primary agent
o Aetiological agent
o Facultative anaerobe
o Survives environment 7 days
o Present in normal sheep feet at low levels
o Virulence factors
Fimbrae finger like projections (basis for serotyping 10)
Proteases – digest protein = can digest horn - Fusobacterium necrophorum can also be involved but not main (like BFR)
o Anaerobe
o Gut, faeces, widespread in the environment
o Often found in footrot lesions but considered common secondary invader
12
Q
Interdigital term treatment
A
- no under running horn
- Topical - Oxytetracycline spray and/ or Footbathing in antiseptic formalin 3% Zinc sulphate 10% solutions
- Systemic antibiotics - LA oxygen however not suusally necessary. Topical should do the trick
13
Q
Foot bathing is often done badly. What do you need to do?
A
- Clean mud off feet before
- correct conc
- correct depth
- Stand in time approx 2 mins depending on product. This is case for zinc sulphate 10% sol
- must dry straight after
- Antiseptic must reach interdigital area to be effective
- Repeat as necessary
14
Q
Treatment of footrot
A
- under run horn
- Tx as quickly as poss
- ISOLATE sheep - it is a source of infection
- Injectable LA Antibiotic
- LA oxytetracycline: cure rates 70-80% reported. Repeat 4 days later
- LA amoxicillin - 80% cure rate, repeat 48 hrs later
Neither LA antibs have 100% cure which is why have to repeat, keep isolated
Could use macrocodes but higher up in critically important chain so don’t just to these. Use first line
DO NOT TRIM
15
Q
Pros of trimming lame
A
- expose infected tissue to topical oxygen and/ or footpath treatment
- anaerobic bacteria exposed to air
16
Q
cons of trimming for lameness
A
- Trimming delays healing
- Spread disease - hands and clippers
- Studies have shown that if you treat the infection with antibiotics the foot shape will return to normal alone
- could cut to sensitive laminae = pain
17
Q
CODD facts
A
Contagious ovine digital derm
- Cause of huge outbreaks severe lameness
- widespread in up to 50 % farms and prevalence on these can be high but not as common as footrot
- starts at coronary badn
- more serious than footrot
18
Q
Clinical signs of CODD
A
o Ulcerative or proliferative lesion starts at coronary band
o Progressive under-running of hoof wall downwards from underlying tissue
o Hoof sloughs off
o Often mixed infections in flocks with footrot problems
19
Q
How do we grade CODD?
A
Grade 1-coronary band lesion only
Garde2-<50% horn capsule separated
Grade 3 - 50-100% hoof capsule off
Grade 4: healing but still active lesion present
Grade 5-Healed
20
Q
How can CODD progress?
A
- Extensive damage to foot
- Even down to the bone - osteolysis in bone. Not just superficial
21
Q
Aetiology CODD
A
- Treponeme bacteria identical to those causing digital dermatitis in cattle strongly associated with CODD, considered necessary cause
o T. mediumT. phagedenis-and T. pedis - Dichelobacter nodosus and Fusobacterium necrophorum also found in CODD feet
22
Q
Bacteria found in the different lameness diseases in sheep
A
Foot Rot: Dichelobacter nodosus
CODD: - Treponeme bacteria identical to those causing digital dermatitis in cattle strongly associated with CODD, considered necessary cause
o T. mediumT. phagedenis-and T. pedis
- Dichelobacter nodosus and Fusobacterium necrophorum also found in CODD feet
23
Q
Risk factors of CODD
A
- Seasonal trend late summer/early autumn
- Large flock size
- Lowland pasture, lush pasture, poached pasture
- Many cases thought to develop originally from footrot/id lesions
- RISK FACTORS FOR CODD VERY SIMILAR TO FOOTROT IMPLICATIONS FOR CONTROL
24
Q
How do we treat CODD?
A
- ISOLATE
- LA amoxicillin 71% cure rate as treponenes are v sensitive to penicillin
- usually require repeated injections until foot completely clean and dried up
- Treat until clinically cured
- Like in FR can use macrocodes as LOOOOOng acting but not first line antibiotic
25
CODD/ Foot rot/ Scald are all infectious foot diseases and v closely related so the same principles can be applied to their control. What is the general management of infectious disease?
1. Biosecurity: preventing disease entry
2. Reduce disease challenge
a. Management : Hygiene, ventillation, stocking rates
b. Test and cull infected animals
c. Drug treatments (antibiotics/anthelmintics)
3. Improve animals resistance
a. Vaccinate
b. Reduce stress
c. Improve nutrition
26
Specific plan for infectious foot disease:
the 5 point plan
- Builds on 5 areas that are Very good principles of infectious lameness disease control
- Whole plan maybe not be appropriate for every flock (e.g vaccination)
- But the principles can be adapted to management of infectious foot disease to all flocks
1. Vaccinate twice yearly Footvax – establish immunity
2. Treat lame sheep quickly
3. Biosecurity plan
4. Reduce environmental challenge – reduce pathogen load
5. Cull chronically lame sheep – build resilience and reduce challenge
27
Talk about foot rot vaccine
1. called footvax
- Against primary agent D nodosus
- Treats AND Prevents footrot = rare for vaccine to do this
- Cure rates 70-100% reported
- Protection rates (60-100%) Very useful in management of footrot
- One study also shown protective effect against CODD
- FR risk factor for CODD
- Mutivalent vaccine containing multiple strains of D nodosus
- Not necessary for all farms but very useful product on many farms, where struggling to keep on top of lameness particularly low staff numbers, large units and where prompt individual treatment isn’t feasible – AID to control
28
Foot rot vaccination warnings
- Oily adjuvant so can get injection site lumps
- Not used prior to shearing
- Not use close to lambing – given sheep “knock”
- Not use if sheep had moxidectin1% as cross react
- Initial vaccination 2 doses 4-6 weeks apart
- 6 monthly booster at risk periods
- Post scanning (housing) Dec
- Post shearing summer-when flock numbers are lowest
- MANAGE EXPECTAITONS
o Stick to programme
o 2-3 yrs for lameness levels to dramatically fall
o Provided continue using vaccine wills tay low
o Long term aid not short term quick fix
29
biosecurity with foot rot
- Bought in sheep
o Don’t buy in new diseases or new strains of disease.
o Consider where buy from?
o Isolate (3-4 weeks)
If sound when come In it gives time for lesions to develop and animals to show lameness
o Treat for anthelmintic resistance
o Treat scab
- Check for foot lesions
o To pick up early lesions
- Footvax farm
o Treat all sheep with Footvax if using on farm
- Find CODD/Footrot
o Particularly if got CODD - Return sheep?
o Whole group antibiotics (intensive treatment, till ensure they are clinically cured ? Even then, can’t rule out if there is a Carrier state)
o Worth taking biosecurity seriously
30
What can you do to reduce wet areas
o Move buckets and feed troughs
o Fix leaky water drinkers
o Dry out gateways (hard core)
o Bedding dry
31
Tx white line disease
- No infection just separation of sole from wall
- Leave
- Can carefully trim out area of separation to prevent stones or soil getting stuck but don’t penetrate into sensitive tissue
- Abscess
- Heat, pain, swelling affected claw
- May burst out at coronary band
- Trim if necessary to release pus, avoid damaging sensitive tissue
32
List non infectious causes of lameness
1. White line disease
2. Soil baling
3. laminitis
4. pedal joint abscess
5. white muscle disease
6. bones disease
7. arthritis
33
What is white line disease known as and what is it
Shelly hoof
- white line separation
- Don’t cause lameness unless sensitive tissue affected
- Lot will have WLD without separation
- Impaction with stones mud etc
- abscess formation
34
Why do sheep get pedal joint abscess
- More common as result extensive infection in foot
- Consequence of white Line abscess
- May not know original cause – severe non Wbearing lameness, hot foot, abscess tracts
- Pus tracts abaxially across the distal interphalangeal joint to emerge at abaxial coronary band
35
CS pedal joint abscess
o animals are severely lame
o the foot is swollen
o the interdigital space is widened
o purulent discharging sinus maybe present on the abaxial coronary band.
36
Tx pedal joint abscess
- Flush and antibiotics Efficacy
- Digit Amputation
37
Digit amputation
- Disarticulation between P1 and P2
- P2 P3 in hoof capsule itself
38
What drugs used for digit amputation
- Sedate
o –Xylazine 0.25-0.5ml i.m
- Local anaesthesia
o Intravenous regional anaesthesia to anesthatise foot
o 5-10ml procaine
o Or ring block round foot
- Clip Clean and Prepare Foot
- Torniquay to stop circulation
- Disarticulate between P1 and P2
- Bandage foot
- Change after 3 or 4 days
- Antibiotic
- Nsaids
- No suturing just clean tissue
39
What is strawberry foot
- Toe granuloma
- The fleshy tissue, normally under the sole horn, grows out as a red pea-sized ball
- caused by foot dmaage especially over trimming or bathing
- can also follow severe cases of footrot and CODD that have not been treated promptly.
- Strawberry footrot
o Long grass, wet fields
o Proliferative scab lesion distal limbs
o Can be haemorrhagic
o Usually orf & dermatophillus (mud fever)–Systemic & topical antibiotics and move to dry fields
40
What is white muscle disease caused by?
selenium and vitamin E deficiency
aka
nutritional muscular dystrophy
41
CS white muscle disease
- STIFF LAME RECUMBENT LAMBS
- Progressing over several weeks to inability to stand
- Skeletal muscle maybe swollen and painful on palpation.
- This condition typically affects groups of young, not individual, rapidly growing, lambs grazing pasture or crops deficient in vitamin E and selenium.
42
How do we diagnose and treat WMD/ nutritional muscular dystrophy
- Diagnosis
o raised glutathione peroxidase levels in blood to test levels of Vit E and Selenium in blood
- Treatment
o –Vit E /Selenium supplementation
43
What is rickets
- Rickets (Vitamin D deficiency)
o Lameness, stiffness.
o Swollen joints, angular limb deformities.
o Diagnosed on blood vit D levels
o Occasional reports of outbreaks of rickets in growing lambs. Caused by vitamin D deficiency which results in impaired mineralisation of physeal and epiphysial cartilage typically affecting the radius, tibia, metacarpals and metatarsals.
44
Arthritis in sheep
- Infectious arthritis – generally talking about lambs that get systemic infection but adult sheep can get infection in due to penetrative injury but mostly dengenerative joint disease
o Neonatal infections
Strep dysgalactaie
Tick pyaemia
1. Staph aureus infection in joints-lambs cripples
Erysipelothrix rhusiopathie – unhygienic environments
- Degenerative Joint Disease
o Chronic lameness of varying severity.
o Elbow joint most commonly affected but also tarsal, carpal, and stifle joints.
o Thickening, effusion, pain and restricted movement of joint (Muscle atrophy and weight loss in chronic cases.
o May occur as a consequence of joint infection (especially in lambs),or trauma.–Radiography can be used to confirm the diagnosis
Further Reading
