Microsoft word - egs.doc

Equine Grass Sickness
What is equine grass sickness? The cause of equine grass sickness is still unknown but it is thought to be caused by a toxin formed by the bacteria Clostridium botulinum Type C. The bacterium is found in the soil and appears to cause a problem when a number of risk factors coincide to increase the susceptibility of certain horses to the disease. It is not contagious. The toxin damages the nervous system, has a high fatality rate and occurs in horses, ponies and donkeys. Clinical signs Three types of grass sickness occur: acute (less than 2 days), sub acute (2-7 days) and chronic (more than 7 days). Signs may include: • Colic • Reduction in number of faeces passed • Difficulty eating and swallowing • Sweating • Excess saliva production – extreme cases foam at the mouth • Drooping of upper eyelids • Dry nostrils • Muscle tremors • Depression • Weight loss in chronic cases Diagnosis of grass sickness cannot be made through clinical signs alone as the above signs can be seen in other conditions. The disease is suspected when other causes of similar signs have been eliminated and often the veterinary surgeon detects high heart rates, lack of gut movement and sometimes excess fluid accumulation in the stomach. Unfortunately a definite diagnosis can only be made post mortem. Treatment There is no treatment for grass sickness and the death rate is high but some chronic cases can survive after often months of nursing. Prevention Researchers are carrying out a vaccination field trial in areas of the UK known to have had cases of Equine Grass Sickness to investigate whether vaccination against Clostridium botulinum Type C toxoid will help to prevent future cases. Results of this trial will become available in 2016. Recently in Guernsey there has been one yard confirmed with grass sickness. Although when cases occur there is considered to be a risk of further cases in a 12 km radius of that site, there are a number of factors known to increase the risk of grass sickness. Isabelle Vets Limited, Route Isabelle, St.Peter Port, Guernsey, Channel Islands, GY1 1QR Tel 01481 723863 Fax 0181 700012 vets@isabellevets.co.uk www.isabellevets.co.uk What are the risk factors? There are three groups of risk factors. 1. Horses at increased risk • 2-7 year old horses • Horses in good to fat body condition • Horses with low antibody status to Clostridium botulinum type C Horses are at a lower risk if older or if grazing alongside a previous case. This is thought to be due previous exposure to the bacteria and its toxin leading to some protective immunity. 2. Yards at increased risk • Those where previous cases have occurred • Those with a large number of horses • Sand/loam soils • High soil nitrogen • Pasture disturbance i.e. excavation, laying of pipes, harrowing • The presence of fowl/domesticated birds • Grazing • Movement to a new pasture or premises • Feed change • Frequent worming with ivermectin based wormers i.e. Eqvalan, Equimax, Bimectin • Mechanical removal of faeces What can I do to protect my horse from Equine Grass Sickness? Practical measures can be imposed to help reduce the risk of grass sickness occurring within the constraints of land availability and yard size. 1. Stable for part of the day if possible – this has been shown to reduce cases. This is particularly important in the Spring and early summer following a dry, cool spell (a temperature of 7-11 º C for 10 consecutive days has been associated with a higher incidence) 2. Avoid disturbing pasture through harrowing, excavations, laying of pipes 3. Avoid soil exposure – do not allow close grazing and avoid turnout in muddy, waterlogged fields (poaching) or provide hay and haylage to eat 4. Avoid sudden changes in feed 5. Avoid stressful situations particularly with high risk horses at peak times of the year 6. Avoid over worming – worm according to the time of the year and worm burden (use worm egg counts) 80% horses do not carry a significant worm burden and therefore do not need worming every 12 weeks 7. Pooh-pick paddocks manually rather than using mechanical removal 8. Graze with sheep or cattle if possible There is no evidence to suggest that any plant or mineral/vitamin deficiencies are linked to an increase risk of equine grass sickness. There is still on-going research into grass sickness and hopefully the vaccination trial will give us positive results in order that we can prevent disease. Further information can be found at http://www.equinegrasssickness.co.uk Isabelle Vets Limited, Route Isabelle, St.Peter Port, Guernsey, Channel Islands, GY1 1QR Tel 01481 723863 Fax 0181 700012 vets@isabellevets.co.uk www.isabellevets.co.uk

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