Lameness in sheep Flashcards
Isses regarding lameness in sheep
huge economic and welfare
Lame sheep, what are your Ddx
- 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
What lesions can appear in association with lameness?
- interdigital hyperplasia
- Overgrown or misshaped claws
- FB
- Soil balling
- Granuloma
What disease processes are associated with lameness?
- Fracture
- Musculature
- Neuro
- Arthritis
MAKE SURE YOU EXAMINE WHOLE LIMB, NOT JUST FOOT!!
Benign foot rod/ Interdigital term/ SCALD about
- 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
BFR/ SCALD/ IDD aetiology
- 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
What bacteria causes Benign footrot/ IDD/ scald?
Dichelobacter nodosus (anaerobic)
Risk factors of footrot
both benign and virulent same
DAMP - grass, trough, gates
Mud
Genetics - heritable susceptibility
high stocking
Will benign footrot progress?
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
Virulent footrot CS
- 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
agent in footrot
- 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
Interdigital term treatment
- 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
Foot bathing is often done badly. What do you need to do?
- 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
Treatment of footrot
- 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
Pros of trimming lame
- expose infected tissue to topical oxygen and/ or footpath treatment
- anaerobic bacteria exposed to air
cons of trimming for lameness
- 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
CODD facts
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