Sheep Lameness

List the diseases associated with foot lameness

• Footrot

  • Benign footrot, interdigital dermatitis, scald

  • Virulent footrot- also affects horn of foot

    

• CODD (contageous ovine digital dermatitis)

• White line disease (white line separation)

  

• Toe granuloma

  

• Foot abscess

• Interdigital hyperplasia

  

• Overgrown or misshapen claws

• Foreign body

• over trimming

• Soil balling

What are some non foot diseases associated with lameness?

• Arthritis

  • Infectious e.g joint ill, septic arthritis

  • Osteoarthritis

• Fractures

• Muscular

• Neurological disease associated lameness

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

How can benign footrot/ interdigital dermatitis/ Scald present?

• benign footrot lesions on own

• Or as part of general footrot problem or mixed infection

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

• lame

• Inderdigital skin inflammed

• No horn separation

(damage to skin may predispose to bacterial infection)

just interdigital NO horn involvement

What are the predisposing factors to benign footrot?

• Damp conditions underfoot

• Frost

• Mechnical damage

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?

• Groups of growing lambs

• Can progress to footrot with underrunning of horn

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

• The virulence and dose of the D. nodosus

• The susceptibility of the sheep

• Promptness of treatment

What are the features of footrot?

• Interdigital dermatitis with progressive underrunning of sole of hoof horn starting at medial aspect of sole and progressing laterally

• Grey necrotic pungent smelling horn

(Virulent footrot)

What is causing these lesions

Footrot

What are the features of dichelobacter nodosus?

• Facultative anaerobe

• Survives in environemnt for 7 days

• Present in normal sheep feet as well

(Virulence factors —> Fimbrae (basis for serotyping 10), Proteases)

What are the features of fusobacterium necrophorum?

• Anaerobe

• Gut, faeces, wideespread in envrionment

• 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

• Gathering

• Genetics

How is benign footrot treated?

no under-running of horn

• Oxytetracycline spray

• Foot bathing in antiseptic solutions

  • Formalin 3%

  • Zinc sulphate

  • Disinfectant footbaths

• Systemic antibiotics LA oxytetracycline (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 beforehand

• Solution correct conc and depth

• Stand in time correct (Zinc sulphate)

• Dry afterwards

How is footrot treated?

under-run horn

• Isolate lame sheep

• Treat individual and group

• Injectable LA antibiotic

  • LA oxytetracycline

  • LA amoxicillin

  • Macrolides- longer acting (tilmicosin (vet only), tulathromycin, gamithromycin)

• May require repeat treatments and use topical ABs + antiseptic as well

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

• May delay healing

• May spread disease through hands and clippers

What is the clinical appearance of Contagious ovine digital dermatitis?

• Ulcerative or proliferative lesion starting at coronary band

• Very severe lameness

• Progressive underunning of hoof wall downwards

• Hoof sloughs off

• Often mixed infections in flocks with issues

What are the different grades of CODD?

cause inflam of sensitive laminae + damage horn producing tissues

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 Contagious ovine digital dermatitis 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 and 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 pasture

• Lush pasture

• 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 long acting- tilmicosin, tulathromycin, gamithromycin

• NSAIDs

• Remove separated horn tissue

How do you prevent infectious foot disease?

• Treat as soon as seen

• Flock level management

  • Five point plan

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

Footrot massive risk factor for CODD so vital to control both together

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?

Footrot vaccine

• Both treats (can cure) and prevents footrot

  • Very useful in outbreak

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

Outline the ABs used to tx lameness in sheep

• Long Acting Oxytetracycline

• Long Acting Amoxicllin

• Macrolides

• Scald – topical antibiotic spray or footbath Zinc Sulphate/Formalin

What enviornmental hygiene should you be mindful of in controllign foot disease?

• Clean and disinfect trimming equipment

• 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 and why?

• Had 2-3 cases of lameness

• Harbour infection in feet, spread it in the flock

• Poor welfare

• Production

  • Less likely to get pregnant, and rear healthy lambs

  • More susceptible to other diseases

• Poor genetics

What is causing this?

• White line disease/shelly hoof

  • seperation of sole + wall at white line

  • A lot will have it without showing signs of lameness (only when sensitive tissue affected)

  • Only show lameness when things get trapped in it/abscess

What is this showing?

A white line abscess

How is white line disease treated?

• Can carefully trim out area of separation (if no infec. + just seperation sole + wall)

If developed into an abscess

• heat, pain + swelling —> poss burst out coronary band

• Trim to release pus and underrun/ separated horn, avoid damaging sensitive tissue

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 and ensure granuloma removed

How do you treat interdigital hyperplasia

Treat clean area and antibiotics

How do you treat soil balling?

Clean, topical anitbiotics

What are the signs of laminitis in sheep?

• Affected animals reluctant to stand due to lameness

• When standing hold all limbs close 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

How do you perform a digit amputation?

• Sedation (Xylazine)

• Local anaesthesia, IV regional or ring block (procaine)

• Clip, clean and prepare

• Disarticulation between P1 and P2

• Bandage foot (change after 3/4 days)

• AB and NSAIDs

What is being shown here?

Overgrowth that has been trimmed back to healthy shape

(overtrimming can cause toe granulomas or white line abscesses)

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

(nutritional muscular dystrophy, stiff lamb disease)

How is white muscle disease 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

• Cast, confine, often successful in young animals

Rickets (Vit D deficiency)

• Vit D and Ca supplementation

How does rickets present?

• impaired mineralisation of physeal and epiphysial cartilage

• affecting the radius, tibia, metacarpals and metatarsals

• Lameness, stiffness.

• Swollen joints, angular limb deformities

What are the two causes of athritis in sheep?

• Infectious athritis

• Degenerative joint disease

  • Can occur as consequence of joint infection

What are some causes of infectious athritis?

• Neonatal infections

  • Strep dysgalactaie

• Tick pyaemia

  • Staph aureus infection in joints- lambs cripples

• Erysipelothrix rhusiopathie

How does degenerative joint dz present?

• Chronic lameness of varying severity.

• Elbow joint most commonly affected but also tarsal, carpal, and stifle joints.

• Thickening, effusion, pain and restricted movement of joint (Muscle atrophy and weight loss in chronic cases.