Alimentary Diseases in Horses Flashcards
Glass Horse CAL
Obstruction
- occurs when normal movement of ingesta is prevented
- bowel that is proximal to obstruction will often expand
- ex: impaction of colon at the pelvic flexure
- ex: adhesions of small intestine
Distention of the Intestine
- excess gas in the intestinal lumen stretches the wall of the intestinal lumen
- dilation: when the stomach is involved
- tympany: when caecum or colon are involved
- most common: caecal tympany, gastric dilation
Spasms
- when the smooth muscles of the intestine dont contract in a well coordinated manner
- the ingesta is supposed to move aborally along the GIT
- these spasms may cause the horse abdominal supply
- the blood supply is not compromised in this case and there is no obstruction to the movement of ingesta
- spasms may occur in small intestine or large colon
Strangulation Obstruction
- Occur when both when the ingesta and the intestinal blood supply are interrupted
- this can occur if the intestine moves through an opening, such as a tear in the mesentery or if the intestine twists enough to occlude the lumen and the vessels
- the affected intestine become aschemic and the intestine proximal to the lesion distends
- examples: large colon volvulus, inguinal hernia, incarceration of small intestine through a mesenteric rent
Ulceration
- Interior of the intestine is covered by a layer of mucosal epithelial cells
- loss of this layer down to the submucosa
Weight Loss in Horse- Possible Differentials
(Inability to Prehend Food)
Inability to prehend food
- Dental disease
- Gastric ulceration
- Foreign body
- Oral/oesophageal mass
- Neurological dx
- Grass sickness
- dysphagia - difficulty or discomfort in swallowing, as a symptom of disease
- Temporohyoid problems
Weight Loss in a Horse- Possible Differentials
(Inability to Absorb Nutrients)
Inability to absorb nutrients
- Inflammatory bowel disease
- Alimentary lymphosarcomma
- Gastric squamous cell carcinoma
- Parasitism
- Grass sickness
Weigh Loss in a Horse - Possible Differentials
(Inability to utilize nutrients)
- Liver Disease
Weight Loss in a Horse: Possible Differentials
(increased metabolic demand)
- Neoplasia
- Chronic Bacterial Infection
- Peritonitis
Weight Loss in a Horse with no known Diarrhea
What tests would you run on a fecal sample?
- Parasitism can cause weight loss, so doing a worm egg count is appropriate.
- Salmonella and Clostridia can cause weight loss, but because of diarrhoea, which this mare does not have, so it would be a waste of the client’s money to run these.
Weight Loss in a Horse with no known Diarrhea, but low total protein/albumin
If the Fecal Egg Count comes back negative…
- Even though the egg count is negative, parasitism could still be a cause of weight loss if encysted cyathostomins are involved - the infection will not be patent.
- Gastroscopy can be used to diagnose gastric ulcers and neoplasia - ulcers seem less likely, because of the low protein and albimin, but neoplasia is a possibility. Duodenal biopsies can also be obtained during the gastroscopy.
- Ultrasound can be used to look for masses and thickening of the intestinal wall - this might suggest infiltrative or inflammatory bowel disease.
- A rectal biopsy may be helpful if there is infiltration in the large intestine which is also affecting the rectum (to get large intestinal biopsies requires surgery, while rectal biopsies can be done in the standing sedated horse).
- A glucose absorption test is easy to do, and can be used to crudely assess the absorptive capacity of the small intestine (there is no test we can run to assess large intestinal absorption)
On US, what should the thickness of the Small Intestine (wall) be normally?
the wall thickness of the small intestine, which should be less than 3-4mm
What would you expect to see in a normal horse after administering 1g/1kg of dextrose as a 20% solution?
- Normal horses will absorb the glucose within 90 mins, and their base line glucose will increase to more than 85% above baseline
Alimentary Lymphoma and Prognosis
- In horses, lymphoma is the most common haemopoietic neoplasm.
- It has been characterised into four main forms: alimentary, cutaneous, mediastinal and multicentric, however, it takes mainly the alimentary form
- Some horses may respond temporarily to treatment, but the prognosis is uniformly poor
Long Term Prognosis for IBD is?
- Guarded
- Some horses will respond to treatment with corticosteroids. The response to treatment can depend on the type of infiltrate
