A Selection of Articles from Recent Issues of Welsh Breeds News

• WORMING ADVICE FOR AUTUMN
• Hay Shortage? Spillers' Advice.
• From The Chairman, and Show Secretary SEWPCA
• Laminitis can kill - warns the Blue Cross
• EMWPCA SHOW - Sec A Results. 25th April 2010
• Scurry driver sings praises of SPILLERS HAPPY HOOF®
• Correction Re: Midlands WPCA Foal Show 2009 report in Issue 74.
• Abandoned pony highlights importance of identification
• Be safe and save money with SPILLERS HAPPY HOOF®
• Blue Cross Appeal for homes for lead rein ponies
• Gwynedd Welsh Pony & Cob Breeders Association Results
• DATES FOR YOUR DIARY
• KEEPING YOUR HORSES SAFE IN WINTER. Advice from the Blue Cross.
• Blue Cross FAT HORSE SLIM Campaign.
• SEWPCA 2009 WPCS BRONZE MEDAL SUMMER SHOW RESULTS.
• FAYRE OAKS SALE 2009
• PHOTOGRAPHS
• Gwynedd Welsh Pony & Cob Breeders Association Show Results 25-5-09
• WPCS Spring Sale Prices, 9th May 2009.
• We'd love to hear from you!
• A lovely Poem
• SPILLERS® help reduce the risk of laminitis
• Royal Welsh Cob Sale October 2008 Prices
• FAYRE OAKS SALE PRICES 2008
• Notts/Derby Charity Bonanza Results 29-12-2008
• HAY SALE RESULTS 4th & 5th OCTOBER 2008
• IMPORTANT ANNOUNCEMENTS!
• Hay Horse and Pony Show Results 27th July 2008. Report and photographs in Issue 66, out in October.
• Lampeter Stallion Show Results 2008. Report and Photographs in Issue 64 of Welsh Breeds News.
• Feet V Fashion
• Feeding Foals
• Ups and Downs at Avonvalley and Beyond
• Diabetes in Horses
• Equine Parasite Control
• Grass Sickness by Rachael Conwell BVetMed CertEM MRCVS
• An Avoidable Tragedy by Jane Lane
• Foal Handling: A feature by John Jones, Horse Listener

Grass Sickness: Rachael Conwell BVetMed CertEM MRCVS

Grass sickness is a condition affecting the nervous function of the intestine, leading to gut paralysis. This is associated with a wide variety of signs, ranging from acute colic to chronic weight loss. Horses, ponies and donkeys can all be affected. The condition has been recognised for almost 100 years, and was the biggest cause of death of working heavy horses in Scotland in the 1920’s and 1930’s, prompting lots of research at this time to try to identify the cause. As horses were used less and less for farming, so the investigations died down. However, the increasing importance of the horse leisure industry in recent times has prompted renewed interest in the search for both a cause and a cure. This was particularly brought to the public attention following the death of the famous racehorse Dubai Millennium from Grass Sickness (GS) in April 2001, sadly proving that any horse can succumb to the disease despite the most intensive and specialist care.

Most cases occur in Great Britain, although it has also been diagnosed in N. Europe. So far, the condition has not been seen in N. America, Africa, Australia or Asia. An identical disease called ‘mal seco’ occurs in Argentina, Chile and The Falklands. Similar conditions have been found to affect dogs, cats and hares.

Despite the fact that the condition has been investigated for more than 90 years, at present an exact cause is not known. It is thought to be multi-factorial, requiring a combination of environmental conditions and individual susceptibility. A type of Botulism toxin is suspected and at present this is the area where most research is being concentrated. Other possible causes include bacteria, chemicals, fungal infections, viruses and plant toxins. At present there are several veterinary centres in the UK, including Liverpool and Edinburgh Universities, involved in investigating the possible causes. All information is shared and it is hoped that there will be a breakthrough before too long.

The condition occurs almost exclusively in horses that are kept at grass. Very rarely, cases have been reported in animals with no access to grass but which have been fed hay. The time of year and area of the country are also significant - most cases are seen in spring, early summer and occasionally autumn. Outbreaks often coincide with a weather change, particularly following a period (at least 10 days) of cool, dry weather and immediately following a ground frost. Certain areas are considered at higher risk, particularly Eastern Scotland and Eastern England, which again may be linked with the weather. Pastures where cases of GS have occurred previously can also be considered at higher risk for the horses grazing there, although sometimes it can be more than 20 years between cases. Some studs or yards have a certain field that is associated with a high occurrence of GS and avoid grazing these pastures during the risk periods.

No. When cases of GS occur, often only 1 horse is affected by the condition from among a group of horses grazing the same field. Rarely, an outbreak can occur, with several animals showing a variety of the signs. Those most at risk are young animals between the ages of 2 and 7 years, with a peak incidence occurring at 3-4 years. Other risk factors have been identified, which include a recent change of pasture and also stress, such as travelling, recent purchase, castration and breaking. Affected animals are often in good condition and no one breed is more susceptible than another. It also does not matter how long a period of time the horse has access to grass.

No. It is not a contagious condition, ie it cannot spread to other horses. Nor can it pass to different species from an affected horse.

Three different clinical syndromes are recognised. However, they are not specific for GS and can often be confused with other conditions. This can make diagnosis very difficult.

Acute: the horse presents with a sudden onset of colic, which is often very painful. Usually there is a high heart rate, dehydration, absence of gut sounds and severe pain, shown by rolling and kicking the belly. This is due to complete or partial paralysis of the gut, which ceases to move gas and food along, leading to rapid distension. There may also be drooling and difficulty swallowing. It can be difficult to distinguish between GS and other causes of colic, such as a twisted gut, in these circumstances and such cases may go undiagnosed, particularly if the horse has to be destroyed. Sometimes a diagnosis may only be made at the time of surgery or at a post mortem examination, if perfomed.

Per-acute: the onset of signs is more gradual, but again characterised by colic. Usually the signs are milder and there is often also sweating and muscle tremors. An unusually high heart rate is common. Your vet may feel a firm impaction when an internal examination is performed. These impactions do not respond to the usual treatment of fluids and liquid paraffin. The horse may die or require euthanasia. Surviving cases will go on to develop the chronic form.

Chronic: this can be the most confusing form of the disease as the signs can initially be very vague and non-specific. The horse may show all or just one of a number of signs and these can develop over days to weeks. There is often a general malaise and gradual weight loss, although in some cases the weight loss can be rapid and dramatic, with affected horses developing a greyhound appearance. Patchy sweating, high heart rate and difficulty eating are also characteristic. Some horses produce only small amounts of mucus-coated, bullet-like droppings, and may have rock solid impactions. This again is due to the reduced gut movement and very slow passage of food through the intestine.

How is GS diagnosed?

Because of the wide variety of signs and different presentations, GS can be difficult to diagnose. Sometimes a diagnosis can be made based on the history and clinical signs alone, but in other cases it may be necessary to remove a small piece of intestine for specialised examination to look for certain degenerative changes in the nerve cells of the gut. This has to be performed under a general anaesthesia and requires specialist facilities. Occasionally it is not until a horse undergoes emergency surgery for a suspected twisted gut that it is found to be actually suffering from GS.

At present, there is no cure. Treatment is mainly supportive and only the chronic form has a chance of survival. The per-acute/acute cases do not survive.

Successful treatment of chronic cases involves lots of expense, intensive nursing and can take many months. The University of Edinburgh have set up a successful unit to treat such cases, with dedicated nurses providing continuous care. However, there are rigid selection criteria that the horse must pass first, as only certain cases will be suitable for attempted treatment.

Treatment includes the use of drugs to stimulate gut movement, intravenous fluids where necessary, regular grooming care and provision of small amounts of easily swallowed, high-energy food to encourage the horse to eat. The prognosis for chronic GS is guarded, but in successful cases, it is possible for affected horses to eventually return to their previous level of work.

Because the cause is unknown, it can be difficult to advise appropriately following a case of GS. Certain premises appear to be more prone to GS and it is occasionally possible to even identify a specific field that has a higher risk. Obviously, there is great concern on yards when a case of GS occurs, or if there is a history of previous cases on the grazing. General advice includes avoiding access to grass in prevalent areas during the risk period, ie spring and early summer, or following a persistent period (10days) of dry cool weather (7 - 10°C), and grazing ‘risk’ fields with other stock during the spring and summer. It is probably advisable to move other horses off the pasture when a case of GS occurs, although obviously this in itself may be associated with stress and change, which are among the risk factors for GS. Usually only one horse will be affected - rarely there may be outbreaks of GS on a farm, with a number of horses showing a range of the signs.

Grass Sickness is a distressing disease for both the horse and the owner, particularly because it tends to affect younger animals only just at the start of their career. Early diagnosis is important, but can be difficult and affected horses often have to be destroyed. Treatment is possible in some cases and is both intensive and expensive. Currently there is no cure, but it is hoped that soon the cause will be identified, allowing more specific preventative measures or possibly even a vaccine.