Foot Abscess 'Sweerklou' Trial
By Dr Mackie Hobson BSc(Agric),BVSc

1. Field Studies

Background

 Foot abscess (‘sweerklou’) is a significant problem on many Angora farms leading to the loss in condition, loss in mohair and reproductive performance. The term ‘sweerklou’ or ‘foot abscess’ is often confused with ‘footrot’’ vrotpootjie’ which is a different condition effecting the hooves of the goat.

 The reason that the joint is so susceptible to infection and abscess formation is that on the interdigital aspect the joint capsule protrudes (dorsal and volar pouches) above the coronary (hoof) border. At these sites the joint capsule is only protected by the interdigital skin and minimal amount of subcutaneous tissue.

The infection causing the foot abscess enters through the disruption of the skin and entry into the joint capsule due to:

• Mouthparts of ticks Rhipicephalis glabroscutatem (smooth brown tick) and R. simus (glossy brown tick) as well as Ambyomma (bont tick) and Hyalomma (bont legged tick) species.
• Softening of the interdigital skin after rain predisposes the skin to injury and the hoof sink deeper into soft soil causes abrasion of skin by soil particles.
• Thorn penetration of skin around hooves
• Grass seed penetration.

Clinical signs

 The symptoms are obvious in terms of lameness.

 Initially the foot becomes warm to the touch and is painful if pressure applied.

 The swelling then develops above the hoof margins.  The digit is markedly swollen and can burst open and

discharging pus is visible.

If a severe septic arthritis develops the effected joint will often never fully recover due to the arthritic changes caused by the infection.

FIELD TRIALS -Effect of vaccination on Foot Abscess outbreaks.

Background

In 2013 SAMGA performed a field trial on the farm of Haydn Krige.

• Corynebacterium pseudotuberculosis ( ovis) was cultured as being the secondary pathogen in the cases of ‘sweerklou’ identified on the farm.

Both Angora kids and ewes were vaccinated with Corynebacterium pseudotuberculosis.(Glanvac3 Zoetis)

It was found that:

• There was NO significant difference between the vaccinated and unvaccinated goats as to the incidence of ‘sweerklou’. That is the vaccine had no effect on the incidence of the occurrence of foot abscess’.
• The cultures taken from the infected goatswere found to be Corynebacterium pyogenes. There were no cases of Corynebacterium pseudotuberculosis/ovis (against which the goats were vaccinated).

It was decided then to block both infected agents on another farm the following year. 2014/15 belonging to Roy Heydenrych- Angora

Objective of the trial:

• Determine if vaccinating Angora goats reduces the incidence of foot abscess occurrence in a flock where the vaccines Corynebacterium ovis and Actinomyces pyogene are administered.

• The names of the bacteria have changed over the years as indicated below:
• Corynebacterium ovis

1. pseudotuberculosis

• Corynebacterium pyogenes

                                Actinomyces pyogenes

                   Acranobacterium pyogenes

                                 Trueperella pyogenes

METHOD:

• A flock of Angora goat ewes(305) and kids (315) used in the study
• The flock was randomly divided into:
• Kids (158 vaccinated/157 control)
• Ewes (153 vaccinated/153 control)
•  The VACCINATION group of 158 kids and 153 ewe  marked with  ear tags

• Vaccinate tagged goats with vaccine following manufacturer’s recommendations

Corynebacterium 2ml s/c both ewes and lambs

Actinomyces 2ml s/c for kids and 5ml s/c for ewes

• Both the control and vaccinated ewes and kids were then put through a foot dip containing Kerol Veterinary fluid) diluted 1ml/litre water, Swavet CuSO4 500g/100litre water and Maxi-Cyp 20% (Cypermethrin).
•  Normal preventative weekly/alternate weekly footbaths were continued during the trial.
•  At inspections goats were removed, isolated and treated that clinically presented with ‘sweerklou’/Footabscess.
•  Goats that were lame due to ticks and had not developed a foot abscess were treated as with the normal preventative tick treatments on the farm.

RESULTS:

Goats that developed Foot abscess (‘Sweerklou’)

Of the 35 goats removed from the herd and isolated due to the development of Foot Abscess (‘Sweerklou’) from December 2014 to March 2015

• 34 were from the unvaccinated group
• 1 goat from the vaccinated

Samples for culture were taken and sent to Onderstepoort for analysis to determine the pathogen causing the foot abscess’

CONCLUSION:

Vaccinating goats with Corynebacterium ovis and Actinomyces pyogenes had a significant effect on REDUCING the incidence of  foot abscess on the farm.

PRACTICAL IMPLICATIONS- FEASABILITY

Vaccination intervals:

• Actinomyces vaccine requires 3 vaccinations (2ml s/c for kids and 5ml s/c for adults) at 10-14 day intervals
• Corynebacterium vaccine requires 2 injections (2ml s/c) a month apart
• Single booster vaccination 6 months later

Costs:

Approximate costs (exl VAT) April 2015