7.1.3: Mild colic and grass sickness Flashcards
A horse presents with colic and pyrexia. What are your differentials?
- Peritonitits
- Colitis
- Enteritis
- Non GI causes: pleuropneumonia and other infections
You are considering a diagnosis of peritonitis. What findings might you see on haematology?
- Leukopaenia
- Haemoconcentration/azotaemia/acidosis
- Increased acute phase proteins
You are considering a diagnosis of peritonitis. What findings might you see on abdominocentesis?
- TNCC greater than 5 x 10⁹
- Supportive cytological findings: neutrophils, macrophages, lymphocytes
- Lactate >2mmol/L
- Glucose <2 mmol/L
- Culture and sensitivity
What treatment would you administer to a horse with peritonitis?
- Antibiotics: penicillin and gentamycin
- IV fluids
- ± Abdominal lavage/drainage
What factors affect the prognosis of a horse with peritonitis?
- Depends on the source of contamination
- If GI rupture -> poor prognosis
- If after abdominal surgery -> guarded prognosis
- If peritonitis occurs without GI rupture -> generally good prognosis
Which equids are affected by grass sickness?
- Horses
- Ponies
- Donkeys
What are some risk factors for grass sickness?
- Being out at pasture
- Being on pasture that has a history of grass sickness cases
- Presence of domesticated birds on the field
- Stress
- The horse being in good-fat BCS
- Cool dry weather with temp. between 7-11C
- Frequent worming
What is equine grass sickness and what is causal agent?
- Equine grass sickness: a dysautonomia affecting primarily the enteric nervous system. There is a decrease in GI motility with a decrease in GI secretions. It is mainly the PSNS affected.
- Causal agent unknown, likely associated with levels of some toxin.
What clinical sign of equine grass sickness is shown here?
“Greyhound abdomen” - the horse is extremely tucked up with pain
How can we categorise equine grass sickness cases?
- Acute - these cases die rapidly
- Subacute - these horses survive >2 days
- Chronic - these horses survive >7 days
What are the clinical signs of acute grass sickness?
- Severe gut paralysis leading to signs of acute colic
- Difficulty swallowing
- Drooling saliva
- Nasogastric reflux
- Mucus-coated, hard droppings (evidence of slow passage through the GIT)
- Muscle tremors and patchy sweating
- Tachycardia (60-80bpm)
These horses usually die or are euthanised within 2 days of clinical signs.
What are the clinical signs of subacute grass sickness?
- Similar to the signs for acute but less severe
- Difficulty swallowing
- Mild-moderate colic
- Sweating and muscle tremors
- Weak with low head carraige, standing with legs underneath them (“elephant on a barrel”)
- Rapid weight loss
- May eat small amounts of food
May die or be euthanised within 1 week of clinical signs.
What are the clinical signs of chronic grass sickness?
- More insidious than signs of acute and subacute
- Mild or intermitten colic
- Reduced appetite
- May have some difficulty eating, but salivation/gastric reflux/ileus are not a major feature
- Rapid and severe weight loss/emaciation
- Triangular, tucked up “greyhound” abdomen
Some of these horses may recover.
What diagnostic tests could you perform to investigate equine grass sickness?
- Ileal biopsy
- Rectal biopsy
- Phenylephrine
- Oesophageal endoscopy
What is considered the best diagnostic test for equine grass sickness? Why might you choose not to perform it?
- Best diagnostic test = ileal biopsy
- However, this requires laparotomy (either flank or midline) which is associated with decreased survival
- Therefore, by chasing diagnosis with an ileal biopsy, we may be decreasing the horse’s chance of survival
What findings would you see on ileal biopsy of a horse with grass sickness?
- Neuronal degeneration within the autonomic ganglia
- There is depletion of the autonomic ganglia in other parts of the body
- There is vacuolation of cells
In chronic equine grass sickness, pathology is localised to the ileum. In acute disease, there is generalised intestinal pathology.
