Equine Grass Sickness.

Front 1

What is the definition of grass sickness?

Back 1

Polyneuropathy.

Degeneration of neurons of the autonomic nervous system including the enteric nervous system.

Also involvement of the somatic nervous system has been reported.

Front 2

What is the aetiology of equine grass sickness?

Back 2

Unknown.

Several infectious and toxic agents haven been proposed.

Currently believed to be toxicoinfection with C. botulinum C and D or pasture associated mycosis.

Front 3

What age of horses tend to get equine grass sickness?

Back 3

2-7 years.

Front 4

In terms of BCS what condition of horses are more likely to get grass sickness?

Back 4

Horses that are in good BCS or Fat.

Front 5

In terms of immunological status what horses are predisposed to getting equine grass sickness?

Back 5

Horses with low antibody levels to C. botulinum type C surface antigen and BoNT/C increased.

Front 6

In terms of season and weather when are grass sickness outbreaks usually seen?

Back 6

Increased incidence in the summer and spring.

Cool and dry weather.

Front 7

What are premises related factors for equine grass sickness?

Back 7

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.

Front 8

What management related factors increase/ decreasing the risks of equine grass sickness?

Back 8

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.

Front 9

How are the clinical signs of grass sickness subdivided? What do each of these reflect in terms of severity of the disease?

Back 9

1) Acute--> severe

2) Subacute--> moderate.

3) Chronic--> mild

Reflect the severity of neuronal loss particularly in the enteric nervous system.

Front 10

Clinical signs attributable to autonomic derangement and what types of disease are the seen with?

Back 10

- Tachycardia ( A/SA/C)

- Dysphagia (A/SA/C)

-Salivation (A)

- Bilateral Ptsosis ( A/SA/C)

- Sweating ( A/SA/C)

- Rhinits sicca (C)

Front 11

Signs of grass sickness that are attributable to enteric nerve derangements?

Back 11

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

Front 12

Other clinical signs with grass sickness and what types of grass sickness to they appear with?

Back 12

Dull demeanor ( A/SA/C)

Tucked up abdominal silohuette ( SA/C)

Penile prolapse ( C)

Muscle fasiculations (A/SA/C)

Front 13

How do we diagnose equine grass sickness?

Back 13

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.

Front 14

What are gross pathological findings with acute (severe) EGS?

Back 14

Oesophageal erosions associated with reflux oesophagitis.

Gastric and small intestinal distension with fluid.

Front 15

What are gross pathological findings with moderate subacute EGS?

Back 15

Impaction of the large colon with dry ingesta.

Black coating over firm ingesta adherent colonic mucosa.

Front 16

Gross pathological findings with chronic grass sickness?

Back 16

Lack of ingesta and apparent shrinkage in the GIT.

Emaciation of the carcase.

Front 17

What cases of grass sickness have a 100% mortality rate? Is there anything we can do to treat?

Back 17

100% mortality.

Supportive care like I/V fluids, analgesics, and recurrent gastric decompression until definitive diagnosis made.

Front 18

What cases of grass sickness may be treated and how?

Back 18

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.