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18 Cards in this Set
- Front
- Back
What is the definition of grass sickness?
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Polyneuropathy. Degeneration of neurons of the autonomic nervous system including the enteric nervous system. Also involvement of the somatic nervous system has been reported. |
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What is the aetiology of equine grass sickness?
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Unknown.
Several infectious and toxic agents haven been proposed. Currently believed to be toxicoinfection with C. botulinum C and D or pasture associated mycosis. |
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What age of horses tend to get equine grass sickness?
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2-7 years. |
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In terms of BCS what condition of horses are more likely to get grass sickness?
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Horses that are in good BCS or Fat.
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In terms of immunological status what horses are predisposed to getting equine grass sickness?
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Horses with low antibody levels to C. botulinum type C surface antigen and BoNT/C increased.
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In terms of season and weather when are grass sickness outbreaks usually seen?
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Increased incidence in the summer and spring. Cool and dry weather. |
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What are premises related factors for equine grass sickness?
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Large numbers of horses with young horses aged 2-7 years old. Soil that is sandy and loam (fertile clay, silt etc) is at increased risk. Soil nitrogen is higher. Previous outbreaks increased incidence. |
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What management related factors increase/ decreasing the risks of equine grass sickness? |
Grazing: strong association with access to grass.
Dietary change. Movement/stress--> esp. movement onto new pastrure. Pasture disturbance- moles, construction like digging. Antihelmintic treatment--> ivermectin based. Dropping removal--> Mechanical increased risk whereas manual less risk Grass cutting reduces the rate. |
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How are the clinical signs of grass sickness subdivided? What do each of these reflect in terms of severity of the disease? |
1) Acute--> severe 2) Subacute--> moderate. 3) Chronic--> mild Reflect the severity of neuronal loss particularly in the enteric nervous system. |
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Clinical signs attributable to autonomic derangement and what types of disease are the seen with? |
- Tachycardia ( A/SA/C) - Dysphagia (A/SA/C) -Salivation (A) - Bilateral Ptsosis ( A/SA/C) - Sweating ( A/SA/C) - Rhinits sicca (C) |
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Signs of grass sickness that are attributable to enteric nerve derangements? |
Gastric reflux- ( A/SA)
Acute large volumes. No or little volumes passed with subacute. Faecal alterations- (A/SA/C) AGS-and SA- dry faecal balls in rectum coated with thick white mucus. C- Scant, dry mucus covered faeces in the rectum |
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Other clinical signs with grass sickness and what types of grass sickness to they appear with?
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Dull demeanor ( A/SA/C)
Tucked up abdominal silohuette ( SA/C) Penile prolapse ( C) Muscle fasiculations (A/SA/C) |
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How do we diagnose equine grass sickness? |
Clinical signs-> Rhinitis sicca, reflux, paraphimosis, bilateral ptsosis, fasiculations, tucked up silhouette. Rectal findings- firm secondary large colon or caecal impaction. Elimination of diseases with similar signs. Nasogastric intubation- reflux in A/SA. Ultrasound. Phenylephrine eyedrops. Oesophageal ulceration on endoscopy or pass barium revealing poor motility. Histo path of the autonomic and enteric ganglia--> ileal biopsy at ex lap. |
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What are gross pathological findings with acute (severe) EGS? |
Oesophageal erosions associated with reflux oesophagitis.
Gastric and small intestinal distension with fluid. |
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What are gross pathological findings with moderate subacute EGS?
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Impaction of the large colon with dry ingesta. Black coating over firm ingesta adherent colonic mucosa. |
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Gross pathological findings with chronic grass sickness? |
Lack of ingesta and apparent shrinkage in the GIT. Emaciation of the carcase. |
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What cases of grass sickness have a 100% mortality rate? Is there anything we can do to treat?
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100% mortality. Supportive care like I/V fluids, analgesics, and recurrent gastric decompression until definitive diagnosis made. |
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What cases of grass sickness may be treated and how? |
Chronic EGS cases who have some ability to drink and swall. Abscense of cont moderate to severe colic signs. Intensive nursing care- providing highly palatable high energy high protein foods. Encourage to feed by hand feeding. Regular analgesia for post prandial colic episodes. GIT motility enhancers and appetite stimulants can be tried. |