Diarrhoea in the adult horse

Question 1

What is diarrhoea?

Answer 1

▪Increased frequency and change in consistency of faeces
▪Some may use the term interchangeably with colitis.

Question 2

Causes of acute d+ in adult horses

Answer 2

▪Salmonella spp.
▪Clostridium difficile
▪Clostridium perfringens
▪ Coronavirus ▪Cyathostomiasis
▪Anti-microbial Associated
▪Right Dorsal Colitis
▪Grain overload
▪ Dietary

Question 3

Clinical Signs + Complications of acute d+

Answer 3

▪Cow pat to high volume hosepipe D+++
▪Quiet to depressed
▪Colic
▪ Fever
▪ Hypovolaemia
▪ SIRS
▪ Laminitis
▪Secondary infections
▪Have a significant risk of deteriorating rapidly

Question 4

Salmonella spp

Answer 4

• Some serovars are zoonotic
• Nosocomial
• Common to have large volume watery D+
  – Bacteraemia
• Intermittent shedding

Question 5

Clostridiosis

Answer 5

• Most commonly: Antimicrobial associated and nosocomial
• Part of the normal flora in all ages→Low numbers (Do not produce toxins)
  – Toxins produced→disease
• Clostridium difficile and Clostridium perfringens mainly

Question 6

Coronavirus

Answer 6

• Recently emerged as a enteric pathogen→Adults 2011
• Can be associated with outbreaks
• Risk factors not fully understood → Similar to others?

Question 7

Cyathostomiasis

Answer 7

• MOST important equine parasitic disease
  – High prevalence
  – Can have severe clinical signs
• Pre-patent disease
• Most commonly seen in spring
  → Sudden mass emergence → Clinical disease
  – mucosal injury
  – ulceration
  – inflammation

Question 8

Antimicrobial associated colitis

Answer 8

• Disruption of GI flora → Lack of competition for nutrients → Pathogenic bacteria able to proliferate
• Obligate anaerobe population of the flora is most important →Antibiotics affecting these have a higher incidence of causing D+

Question 9

Right Dorsal Colitis

Answer 9

• NSAID Toxicity →Often in horses receiving higher than licensed doses
  – Can still occur with normal dose
  – Does not have to be long term use
  – Can occur in normovolaemic horses at normal doses
• Changes GI blood flow
  – Affects protective mechanism
  – (Multifactorial)

Question 10

Grain Overload

Answer 10

• History of horse gaining access to large quantity of hard feed
• SI digestion overwhelmed and soluble CHO enters LI
• Rapid fermentation by lactic acid producing bacteria lowers pH → Gram negative bacteria die → endotoxin released - Other bacteria overgrow and gut wall becomes compromised → Bacteria and toxins enter the circulation

Question 11

Dietary

Answer 11

• Imbalance?
• Abnormal fermentation?
• Change in flora?

Question 12

Risk factors for acute d+

Answer 12

▪ Gastrointestinal disease
▪ Immunosuppression
▪ Antimicrobials
▪ General anaesthesia
▪ Recent abdominal surgery
▪ Hospitalisation
▪ Other horses
– e.g. those acutely infected and actively shedding, or silent carriers intermittently shedding it
▪ Dietary changes

Question 13

Causes of chronic d+ in adult horses

Answer 13

▪Salmonella spp.
▪Cyathostomiasis
▪Right Dorsal Colitis
▪Sand enteropathy
▪Inflammatory Bowel Disease
▪ Dietary

Question 14

Clinical Signs + Complications of chronic d+

Answer 14

▪Cow pat to D+++
▪Bright to depressed
▪Colic
▪ Fever
▪Ventral oedema
▪Weight loss
▪Electrolyte imbalances
▪Often normovolaemic
– As able to cope and maintain their hydration status

Question 15

Sand

Answer 15

▪Often associated with acute intestinal obstruction
▪ However
– Chronic sand-induced D+ is a separate syndrome
– Abnormal accumulation of sand in the large intestine

Question 16

Risk factors of san causing d+

Answer 16

▪Pasture access on sandy soil
▪Overgrazed pastures
▪Fed on the ground

Question 17

Inflammatory Bowel Disease

Answer 17

▪Multisystemic eosinophilic epitheliotropic disease (MEED)
▪Granulomatous enteritis
▪Lymphocytic/plasmocytic enteritis/colitis
▪ Lymphosarcoma

Question 18

Salmonellosis – Risk Factors

Answer 18

• Recent abdominal surgery
• GI dz (small colon impaction)
• Immunosuppression
• Antimicrobials
• GA
• High ambient temp
• Prolonged hospital stay
• Horses actively shedding or carriers

Question 19

C.difficile

Answer 19

▪More common than perfringens
▪Often associated with antimicrobial associated colitis
▪Could be a reservoir
for human Clostridium
difficile infection

Question 20

C.perfringens

Answer 20

▪Type A and C most common
▪Toxins produced→disease
▪Seen with haemorrhagic D++
– Mainly neonates but adults too

Question 21

Clostridiosis – Risk Factors

Answer 21

• Dietary changes
• Hospitalisation
• Antimicrobials
• GI dz
• Not fully understood

Question 22

Cyathostomins – Life cycle

Answer 22

▪Pre-patent period 6 - 14 weeks
▪Can remain encysted from weeks to 2 Years
▪Encysted, hypobiotic larvae unaffected by most anthelmintics
▪For various reasons, IL3 emerge in Spring, often many many at once

Question 23

Cyathostomiasis- Risk Factors

Answer 23

▪ Age
▪ Season
▪Period since last anthelmintic
▪Altered host immunity
▪ Stress?
▪Dietary changes?
▪Unknown factors

Question 24

NSAID side effects in adult horses

Answer 24

Gastrointestinal
* Right dorsal colitis
* MUCH MUCH more common than causing gastric ulceration

Renal
* Medullary crest necrosis

Question 25

Are ponies or horses more susceptible to NSAID toxicity?

Answer 25

• Ponies

Question 26

RDC risk factors

Answer 26

▪ NSAID administration
▪ More common with oral phenylbutazone
– Less so with COX-2 selective drugs

Question 27

Signs of grain (carb) overload

Answer 27

• SIRS
• osmotic d+ due to lactic acid being poorly absorbed
• severe (often-fatal) laminitis

Question 28

Grain overload- Risk Factors

Answer 28

▪Access to large quantity of grain
▪Amount needed to cause D+ varies
– Horses that are fed diets high in soluble CHO are more resistant

Question 29

What is a nosocomial infection?

Answer 29

• picked up from or giving it to a hospital

Question 30

Do dietary causes of d+ tend to cause a mild or severe d+?

Answer 30

• milder

Question 31

Why can you get ventral oedema as a complication of chronic d+?

Answer 31

• due to chronicity and loss of albumin -> decreased osmotic pressure

Question 32

Why can sand cause chronic d+?

Answer 32

• irritation of the mucosa