Page 1383 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

1358 CHAPTER 14

VetBooks.ir • Peripartum asphyxia: Foals with a hypoxic • Protozoal: Cryptosporidium parvum most
insult and subsequent reperfusion injury
commonly causes gastroenteritis and diarrhoea
in the peripartum period may suffer from
in immunocompromised foals.
damage to the GI mucosa, leading to • Parasitic: Strongyloides westeri, Parascaris spp.
diarrhoea. These foals are also at risk of sepsis and large and small strongyles can all cause
and therefore infectious causes of diarrhoea diarrhoea due to migrating larval damage,
should always be considered in such cases. subsequent inflammation and vascular
• Bacterial: Clostridium. difficile, Salmonella damage, motility disturbances and significant
spp., C. perfringens, E. coli, Campylobacter protein leakage. Transmission of S. westeri is
spp., Rhodococcus equi, Bacteroides fragilis, transmammary or transcutaneous. Many of
Aeromonas hydrophilia and Actinobacillus equuli these diseases are more significant in the older
have been implicated, with varying degrees foal and weanling.
of evidence. Some bacteria, such as E. coli,
after adhering to the gut mucosa, are able to Transfer of passive immunity via colostrum in
produce enterotoxins, which are absorbed the first 24 hours of life is important in the pro-
and then affect the secretory patterns in tection of foals against diarrhoea, particularly for
the gut, leading to watery and profuse infectious causes. Where the transferred local and
diarrhoea. Other bacteria, such as Salmonella systemic immunity is high against the local patho-
and Clostridium spp., invade the bowel wall, gens, the foal is more effectively able to withstand an
causing extensive mucosal and submucosal infectious challenge, unless it is overwhelming. The
damage and sloughing, which heals slowly. pathophysiological consequences of diarrhoea in the
The loss of the mucosal barrier increases the foal can be very serious, with rapid and substantial
vulnerability of the foal to bacterial invasion, deficits and changes in fluid and electrolyte balance.
bacteraemia and septic shock. Inflammatory These can quickly lead to circulatory shock, collapse
cellular infiltration and oedema in the deep and death within hours.
layers of the intestine impair absorptive and
secretory functions. Intestinal spasm may Clinical presentation
lead to colic signs or ileus. The diarrhoea is A full clinical history of the individual and farm
profuse and foetid and may contain blood. involved should be taken and assessed. It is important
Haemorrhagic faeces are most commonly to gather data on the effectiveness of transfer of pas-
associated with clostridial enteritis, which sive immunity to the foal and its health status, age,
carries a poorer prognosis. Lawsonia feeding/sucking, nutrition, duration of signs and gen-
intracellularis is a cause of protein-losing eral demeanour. The epidemiology of the premises on
enteropathy in older foals, and is discussed in which the foal is kept should be thoroughly explored,
more detail elsewhere (see p. 814). especially movements in or out, the preventive disease
• Viral: Rotavirus and coronavirus can cause mild measures in place, the health status of all animals on
mucosal cellular damage, particularly at the the premises and previous problems. Many infectious
tips of the intestinal villi, which interferes with pathogens, such as Clostridia spp., Salmonella spp. or
disaccharidase function and sodium–glucose rotavirus, cause disease in outbreaks.
co-transport proteins, leading to maldigestion A full clinical examination should be performed
and malabsorption. The cellular damage is including abdominal auscultation and assessment of
transient, but the osmotic drawing of fluid into hydration status. The diarrhoea itself should be evalu-
the bowel leads to diarrhoea in the foal because ated because its consistency and volume can vary con-
the colon and caecum in foals up to 3 months of siderably and are important when calculating fluid
age are unable to compensate for small intestinal losses. Haemorrhagic diarrhoea indicates an entero-
pathology. Rotavirus infections are common in invasive pathogen (Fig. 14.25). Abdominal pain is
suckling foals and are highly contagious. variable and some foals with low-grade abdominal