What is Grass Sickness ?
Equine grass sickness (EGS) is a rare, oft-fatal disease that has been striking horses and donkeys in Great Britain and parts of Northern Europe for over a century. Grass sickness has been documented almost always in horses that are over two years of age, and shows no preference for male or female animals. EGS was first documented in Scotland in 1909. Over the course of the next twenty years, hundreds of horses across Scotland were dying annually from grass sickness. While contemporary numbers are far less staggering, the fact that grazing horses are still dying from grass sickness at a rate of 1 in 200 per annum in parts of the UK is distressing. More concerning is that decades of research have not yet isolated the cause of grass sickness, though a link between soil and bacterium Clostridium botulinum (C. botulinum) type C is being explored. This bacterium may be causing horses to create a neurotoxin within their intestines.
The disease causes extensive damage throughout the involutory nervous system of the horse, as well as the gastrointestinal tract. An affected horse will quickly display symptoms of colic, such as excessive sweating, pawing, difficulty swallowing and anxiety. Gastrointestinal symptoms will range from reflux, vomiting and constipation. In total, there are three forms of grass sickness, all of which share symptoms such as reflux, excessive salivation and drooling, constipation, and lack of appetite. The three types branch out significantly when it comes to severity of the symptoms, the extent of damage caused throughout the body, and the likelihood of survival.
In all, the disease is thought to carry a mortality rate in excess of 85%. Many animals affected by EGS deteriorate rapidly and die within 48 hours of the first sign of stomach distress. Other equids presenting with signs of EQS are quickly euthanized to prevent further suffering. For such a serious disease, and one that has been painfully attacking horses for over 100 years, it’s alarming that a cause has not yet been firmly identified. Clearly, due to the severity and fast-moving nature of the symptoms, some type of toxin or poisonous agent must be part of the puzzle. While EQS does not appear to be contagious, there remains no vaccine or no cure.
Equine grass sickness (EGS) is a rare, likely fatal disease that strikes horses, ponies and donkeys mostly in Great Britain and Northern Europe.
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Symptoms of Grass Sickness in Horses
Your horse will exhibit colic-like distress.
- Clear signs of stomach upset and pain
- Rolling and pawing
- Inability to swallow
- Distended stomach
- Odorous secretions
- Muscle tremor
- Lack of appetite
- Rapid and severe weight loss
Types vary according to survivability and severity of symptoms. Though each type presents with colic-like symptoms, such as stomach pain, lack of appetite, and overall bodily discomfort, Acute grass sickness, for example, features a complete inability to swallow, rapid release of bodily secretions, and distended stomach. It is not survivable. A horse can recuperate from the initial acute symptoms of chronic grass sickness, but is still at risk for wasting and will unfortunately experience chronic, though intermittent, gastrointestinal distress.
- Acute grass sickness cases survive 1-2 days
- Subacute grass sickness cases survive 2-7 days
- Chronic grass sickness cases survive more than 7 days
Causes of Grass Sickness in Horses
EGS is continually being researched, and causes remain uncertain.
- Multiple factors are unclear
- Pasture-associated and environmental factors
- Ingesting poison or noxious agents while grazing
- Clostridium botulinum in soil
- Contaminated water or feed
- Unclear combination of risk factors triggering toxic reaction in horse
Diagnosis of Grass Sickness in Horses
EGS bears a specific set of factors which will enable diagnosis. Your horse will become sharply and quickly ill, and will demonstrate severe GI symptoms associated with the condition, along with difficulty swallowing and heart rate abnormalities. Colic symptoms will also be observed. The rapid progression of illness combined with the location of the grazing horse will be telltale enough of EGS to allow for a sure diagnosis.
Treatment of Grass Sickness in Horses
In the slim chance that recovery may occur, the treatment goal will be for your horse to regain its strength. GI symptoms will be addressed with fluids, and appropriate medications to treat vomiting, constipation, and others. Food will be specifically selected to address the severe weight loss.
Recovery of Grass Sickness in Horses
Your horse will remain on the veterinary supervised program. Ongoing management will call for supervised provisions of daily care, opportunities for rest, and a low stress environment.