Page 840 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

Gastrointestinal system: 4.2 The lower gastrointestinal tr act 815

VetBooks.ir intestine is not affected, therefore faecal con- or polymerase chain reaction (PCR) testing of
faeces but these tests are more beneficial for popu-
sistency may be normal even with severe small-
intestinal disease.
lation monitoring than for diagnosis in individual
animals. Coinfection with other enteropathogens
Clinical presentation such as Salmonella spp. and C. difficile can occur,
Foals 3–7 months of age are most commonly therefore testing for multiple pathogens should be
affected. The development of disease is often slow performed.
and insidious. Clinical abnormalities are often On post-mortem examination, much of the small
not noted until the disease is quite advanced. The intestine, mainly the jejunum and ileum, is usually
most common presenting complaints are weight remarkably thickened and corrugated. L. intracellu-
loss, depression, oedema, diarrhoea and ill-thrift. laris can be detected histologically using silver stains.
Colic may be present but is not typical. Foals are Confirmation of the diagnosis can be performed
usually in poor body condition, have ventral and on intestinal tissues via immunohistochemistry or
limb oedema, a pot-bellied appearance and poor PCR.
haircoat. Severe weakness may be present in
advanced cases. Often, multiple foals on a farm Management
will be affected. Antimicrobial therapy is indicated. Antimicrobials
must be able to penetrate intracellularly.
Differential diagnoses Oxytetracycline (6.6 mg/kg i/v q12 h) and doxycy-
Depending on the clinical presentation, intesti- cline (10 mg/kg p/o q12 h) are appropriate first-line
nal parasitism, malnutrition, maldigestion, severe treatments. Erythromycin (erythromycin estolate
EGUS and duodenal ulceration, clostridial diar- 25 mg/kg p/o q6–8 h or erythromycin phosphate
rhoea, salmonellosis, NSAID toxicosis, protein- 37.5 mg/kg p/o q12 h), with or without rifampin (10
losing nephropathy, protein-losing enteropathy, mg/kg p/o q24 h), and chloramphenicol (50 mg/kg
hepatic disease and plant or chemical intoxication p/o q6 h) have been used with anecdotal success.
should be considered. The required duration of antimicrobial therapy is
unclear, and foals are often treated for a minimum of
Diagnosis 21–28 days. Treatment should continue until resolu-
Severe hypoproteinaemia (<40 g/l [4 g/dl]), con- tion of clinical signs and normalisation of the ultra-
sisting of a marked hypoalbuminaemia (<15 g/l sonographic appearance and serum total protein and
[1.5 g/dl], occasionally <10 g/l [1.0 g/dl]) is the most albumin has occurred.
consistent haematological abnormality. The degree Fluid therapy may be required in diarrhoeic foals
of hypoproteinaemia is usually more severe than but should be used sparingly because of the hypo-
would be expected with the severity and duration of proteinaemia. Oncotic support with plasma or syn-
the diarrhoea (if present). Leucocytosis, consisting thetic colloids is often required. The goal of oncotic
of a neutrophilia may be present. Mild to moder- therapy is not to return total protein levels to nor-
ate hyponatraemia, hypokalaemia, hypochloraemia mal, rather to provide oncotic support to alleviate
and hypocalcaemia may be present, particularly in any negative consequences of hypoproteinaemia.
diarrhoeic foals. Thickened loops of small intestine Parenteral nutrition may be required in severely
may be evident on transabdominal ultrasonography affected foals.
with a classic ‘target’ appearance described; however, When one affected foal has been identified on a
these are not always present. farm, all other foals should be considered at risk. It
While a presumptive diagnosis is often made is important for owners to pay close attention to the
based on clinical presentation, severe hypopro- body condition of at-risk foals, ideally through phys-
teinaemia and exclusion of other causes of disease, ical contact. Regular assessment of total protein and
specific testing should be performed. Specific test- albumin may be useful for identifying early disease
ing for L. intracellularis involves serological testing and allowing early intervention.