Sheep lameness

List the diseases associated with foot lameness

• Footrot

  • Benign footrot, interdigital dermatitis, scald

  • Virulent footrot —> also affects horn of foot

    

• CODD (Contagious Ovine Digital Dermatitis)

• White line dx (white line separation)

  

• Toe granuloma

  

• Foot abscess

• Interdigital hyperplasia

  

• Soil balling

• FB

• Overgrown / misshapen claws

What are some non foot diseases associated with lameness?

• Arthritis

  • Infectious e.g joint ill, septic arthritis

  • Osteoarthritis

• Fractures

• Muscular

• Neuro dx ass. lameness

• Make sure examine whole limb/animal not just the foot!

How can benign footrot / interdigital dermatitis (ID) / Scald present?

• As benign footrot lesions on own

• Or as part of general footrot problem or mixed infection

What are the features of benign footrot / ID / Scald?

• Inderdigital skin inflammed, crust & discharge → lame

• No horn underrunning

What are the predisposing factors to benign footrot?

• Damp conditions underfoot → predispose to bact infection in interdigital skin

• Frost

• Mechanical damage from long grass / thistles

What is the main pathogen causing benign footrot?

• Dichelobacter nodosus

• (Fusobacterium necrophorum present in some cases)

In what age sheep are benign footrot outbreaks common? What can these progress to?

• (Risk factors same as footrot)

• Groups of growing lambs

• Can progress to footrot w/ underrunning of horn

What are the factors that determine the progressin of benign footorot to footrot?

• The virulence & dose of the D. nodosus

• The susceptibility of the sheep

• Promptness of tx

What are the features of footrot?

• Interdigital dermatitis w/ progressive underrunning of sole of hoof horn starting @ medial aspect of sole & progressing laterally

• Grey necrotic pungent smelling horn

What is causing these lesions

Footrot

What are the features of dichelobacter nodosus?

• Facultative anaerobe

• Survives in environemnt for 7d

• Present in normal sheep feet as well

• Virulence factors —> fimbrae & proteases

What are the features of fusobacterium necrophorum?

• Anaerobe

• Found in gut, faeces, widespread in environ

• Often found in footrot lesions but considered 2° usually

What are the risk factors associated with footrot and ID?

• Warm

• Wet underfoot conditions

• Muddy

• Housing (lots of animals together)

• Gathering

• Genetics (heritable suscep)

How is benign footrot treated?

• Oxytet spray (topical)

• Foot bathing in antiseptic solutions

  • Formalin 3%

  • Zinc sulphate

  • Disinfectant footbaths

• Systemic antibiotics LA oxytet (Not usually necessary)

What needs to be done to ensure a footbath for benign footrot is done appropriately?

• Antiseptic needs to be exposed to infected interdigital area

• Clean feet beforehand

• Solution correct conc. & depth

• Stand in time correct —> depends on product

• Dry afterwards (concrete)

• Repeat as necessary

How is footrot (under-run horn) treated?

• Treat as quickly as possible

• Isolate lame sheep

• Treat individual & group

• Injectable LA antibiotics best

  • LA oxytet

  • LA amoxicillin

  • LA macrolides e.g. tilmicosin

• May require repeat txs & use AB topical spray as well

What is the problem with trimming as a tx for footrot?

• May delay healing

• May spread disease through hands and clippers

What is the clinical appearance of CODD?

• Ulcerative / proliferative lesion starting @ coronary band

• Very severe lameness

• Progressive underunning of hoof wall downwards

• Hoof sloughs off

• Often mixed infections in flocks w/ issues

What are the different grades of CODD?

Grade 1 —> coronoary band lesion only

Grade 2 —> <50% horn capsule separate

Grade 3 —> 50-100% hoof capsule off

Grade 4 —> healing but still active lesion present

Grade 5 —> healed

What is the consequence of footrot even after it is healed?

• Deformed foot

• Susceptible to maggots

What internal damage can CODD cause?

Can infect bone and cause osteolysis

What aetiological agents cause CODD?

• Treponeme bacteria (same as those causing digital dermatitis in cattle)

  • T. medium

  • T. phagedenis

  • T. pedis

• Dichelobacter nodosus & Fusobacterium necrophorum also found

What are the risk factors for CODD?

• Very similar to footrot

• Large flock size

• Late summer/ early autumn

• Muddly pasture —> lowland, lush, poached

• Lush masture

• Footrot

How is CODD treated?

• Isolate

• LA amoxicillin

  • Usually require repeated injections

• Treat until clinical cure (giving every other day)

• Macrolides licensed for sheep useful as LA —> tilmicosin

• NSAIDs

• Remove separated horn tissue

How do you prevent infectious foot dx?

• Treat as soon as seen

• Flock level management

  • Five point plan

• Same principles can apply to CODD/ Footrot and Scald as very closely related

What is the 5 point plan for foot disease management?

1. Vaccinate twice yearly —> Footvax

2. Treat lame sheep quickly

3. Biosecurity

4. Environmental challenge

5. Cull chronically lame

What are the features of footvax?

• Both treats and prevents footrot

• Very useful in outbreak

• Multivalent vacc containing multiple straains of D nodosus

What are the potential side effects and contraindications of the footrot vaccine?

• Oily adjuvant can cause injection site lumps

• Don't use prior to shearing

• Don't use close to lambign

• Don't use with 1% moxidectin

How often do you have to give the footrot vaccine?

• 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 lowers

How is footrot treated?

• Prompt individual / group isolation & tx —> sheep will get more likely, red. baceria challenge in enviornemt

• LA oxytet

• LA amoxicillin, Mcrolies

• Reapest until clinical cure

What enviornmental hygiene should you be mindful of in controlling foot dx?

• Clean and disinfect trimming equipment

• Don’t buy in sheep → new dx or new strains of dx, consider where buy from, new strains or dx

• Isolate 3-4wks

• Avoid wet muddy areas in field

  • Move buckets and feed troughs

  • Fix leaky water drinkers

  • Dry out gateways

  • Bedding dry

When should you consider culling a lame sheep?

Had 2-3 cases of lameness

What is causing this?

• White line disease/shelly hoof

  • A lot will have it without showing signs of lameness

  • Only show lameness when things get trapped in it

What is this showing?

A white line abscess

How is white line dx treated?

• Can carefully trim out area of separation if no infection

• Developed into an abscess —> trim to release pus and underrun/ separated horn, avoid damaging sensitive tissue → abscess forming

What causes a toe granuloma?

Over trimming

How do you treat toe granulomas?

• IV regional anaesthesia

• LA infiltration

• Cut back granulation tissue

• Cauterise disbudding iron to stop bleeding & ensure granuloma removed

What causes interdigital hyperplasia?

Often secondary infected, may recur

How do you treat interdigital hyperplasia?

Treat clean area & ABs

How do you treat soil balling?

Clean, topical ABs

What are the signs of laminitis in sheep?

• Affected animals reluctant to stand due to lameness

• When standing hold all limbs vlose under abdomen

• Digits warm to touch with inc digital pulses

• Hooves subsq develop horizontal grooves

What can cause laminitis in sheep?

Excess access to high energy or cereal-based feed and acute disease such as metritis or mastitis can predispose to development of laminitis.

How is laminitis treated in sheep?

• NSAIDs

• Address underlying cause

What is the cause of a pedal joint abscess?

• Consequence of extension of interdigital infection into distal interphalngeal joint structures

• Pus tracks abaxially across DIP to emerge adn abaxial coronary band

• Consequence of white line abscess

What are the clinical signs of a pedal joint abscess?

• Severe lameness

• Swelling

• Widened interdigital space

• Purulent discharging sinus maybe

• Present on the abaxial coronary band

How do you treat a pedal joint abscess?

• Flush and antibiotics

• Digit Amputation

What causes digit amputation?

Disarticulation between P1 and P2

How do you perform a digit amputation?

• Sedation (Xylazine)

• Local anaesthesia, IV regional or ring block. 5-10ml procaine

• Clip, clean & prepare

• Disarticulation between P1 & P2

• Bandage foot (change after 3/4 days)

• ABs and NSAIDs

What is being shown here?

Overgrowth that has been trimmed back to healthy shape

What are some causes of non foot lameness?

• Strawberry footrot

• White muscle disease

• Bone diseases

• Arthritis

What is strawberry footrot? How do you treat it?

• Proliferative scab lesion distal limbs

  • Maybe caused by orf & dermatophillus

• Systemic & topical antibiotics and move to dry fields

What causes white muscle disease?

Vit E/ Sel deficiency → stiffness & relutance to move → progresses over several weeks

What are the C/S of white m. dx how is it diagnosed?

• C/S —> progressing to inability to stand, skeletal muscles painful and swollen

• Raised glutathione peroxidase levels in blood

How is white muscle disease treated?

Vit E /Selenium supplementation

What bone diseases can cause lameness? What are their treatments?

Fractures —> sudden onset lameness, pain, swelling

• Cast, confinement, often successful in young animals

Rickets (Vit D def) —> lameness, stiffness, swollen joints, angular limb deformities

• Vit D & Ca supplementation

What are the two causes of athritis in sheep?

• Infectious athritis

• Degenerative joint disease

  • Can occur as consequence of joint infection

  • Elbow joint mostly affected

What are some causes of infectious athritis?

• Neonatal infections

  • Strep dysgalactaie

• Tick pyaemia

  • Staph aureus infection in joints- lambs cripples

• Erysipelothrix rhusiopathie