Infectious foot disease

Question 1

Why are infectious foot diseases important?

Answer 1

• Make animals lame
• Important animal welfare issue
• Reduce milk production
• Expensive to control

Question 2

Where are bovine digital dermatitis lesions located?

Answer 2

Above the coronet between the heel bulbs

Question 3

How does bovine digital dermatitis affect productivity?

Answer 3

• Major cause of lameness: welfare issue
• Milk drop
• Increased culling rate
• Increased labour costs

Question 4

Which organism is most frequently reported in bovine digital dermtitis?

Answer 4

Spirochaetes always seen in BDD lesions; not seen in normal skin

Question 5

Evidence suggests that … are the aetiological agents of Bovine digital dermatitis

Answer 5

Treponemes

Question 6

How is bovine digital dermatitis diagnosed?

Answer 6

Visual - lameness and lesion score

Question 7

How is bovine digital dermatitis treated?

Answer 7

• Footbaths: chemical or antibiotic
• Topical treatments e.g. tetracycline (blue spray)
• Penicillin or macrolides (BUT milk withhold & antibiotic stewardship issues SO NOT USED!)

Question 8

How is bovine digital dermatitis spread?

Answer 8

• Outbreaks within herds tend to be season dependent, with the highest incidence in winter (housing) months
• Cattle can “carry” disease onto new farms
• Cleaner farms have fewer outbreaks
• Ruminant GI tract, slurry, direct contact and foot trimming equipment all identified as infection reservoirs/transmission routes.

Question 9

How does Contagious Ovine Digital Dermatitis grossly affect the foot?

Answer 9

• Starts at the coronary band
• Frequent lesions result in loss of the entire foot horn capsule
• Substantial pain

Question 10

What are the pathogenic organisms causing Contagious Ovine Digital Dermatitis?

Answer 10

Spirochaetes

Treponemes

Question 11

How is Contagious Ovine Digital Dermatitis diagnosed?

Answer 11

Visually - lameness and lesion score

Question 12

How is Contagious Ovine Digital Dermatitis treated?

Answer 12

• Footbaths: chemical or antibiotic
• Topically: tetracycline
• Amoxicillin/penicillin or macrolides

Question 13

What is the primary clinical sign on ovine footrot?

Answer 13

Extremely painful -> rapid weight loss

Can get death from starvation and thirst

Question 14

What is the primary pathogenic agent that causes ovine footrot?

Answer 14

Dichelobacter nodosus

Question 15

How does ovine foot rot grossly affect a sheep’s foot?

Answer 15

Begins as an interdigital dermatitis, then interdigital hoof wall lesions leading to separation of hoof from underlying tissue

Question 16

How is ovine foot rot treated?

Answer 16

• Treatment = hoof trimming?? + topical disinfectants or antibiotics: 5–10% formalin, 5% zinc sulfate or oxytetracycline spray.
• Formalin + zinc sulfate in footbaths.
• Systemic amoxicillin and streptomycin = alternative.
• Vaccination

Question 17

‘Scald’ in sheep is also known as?

Answer 17

Ovine interdigital dermatitis

Question 18

What is the most common cause of lameness in sheep?

Answer 18

Ovine interdigital dermatitis

Question 19

Describe the pathological features of Ovine interdigital dermatitis

Answer 19

• Occurs when wet underfoot
• No under-running of hoof wall or sole & no foul smell
• Now generally considered an early presentation of footrot
• Red/pink inflammation of skin between claws with white/grey pasty ‘scum’ on top

Question 20

Bovine Foul in the Foot is also known as?

Answer 20

Interdigital necrobacillosis

Question 21

Which pathogen is the main cause of interdigital necrobacillosis?

Answer 21

Fusobacterium necrophorum

Question 22

Describe the disease/signs of interdigital necrobacillosis

Answer 22

• Sudden onset, acute disease
• Severe lameness
• Animal frequently holds leg in air to relieve pressure
• Swelling of interdigital space
• Fever, Anorexia
• Reduced milk yield

Question 23

How is interdigital necrobacillosis treated?

Answer 23

• 3 day systemic penicillin, oxytet or macrolide

- Foot bathing with disinfectants to control

Question 24

What are some common characteristics of pathogens that cause infectious foot diseases?

Answer 24

Gram negative and anaerobic also tend to be rods (helical rods in some cases), motile and fastidious.