Page 861 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

836 CHAPTER 4

VetBooks.ir Clinical presentation for population studies than diagnosis of individual
animals. More recently a saliva-based tapeworm
Most horses that are harbouring tapeworms display
no clinical abnormalities, and tapeworm infestation
itself is not thought to produce signs of ill-thrift, test has become available. Adult tapeworms are
uncommonly found in faeces and, if present, might
weight loss or diarrhoea. Clinical signs ranging from suggest a high burden.
ill-thrift to severe colic may be observed as a result
of intussusception, spasmodic colic or ileal impac- Management
tion secondary to tapeworm infestation. These are Most routinely used anthelmintics are not effective
covered in detail elsewhere. against tapeworms and they are often overlooked in
deworming programmes. Pyrantel pamoate can be
Differential diagnosis effective when used at twice the nematocidal dose.
A variety of causes of colic should be considered in Praziquantel (1.0–1.5 mg/kg p/o) is effective against
horses with tapeworm-associated colic. tapeworms, and products containing a combination
of ivermectin (0.2 mg/kg) or moxidectin (0.4 mg/
Diagnosis kg) and praziquantel (1.0–1.5 mg/kg) are available
Faecal flotation is commonly used, but the sensitiv- in many countries. Annual deworming of horses for
ity can be poor depending on the testing methodol- tapeworm is recommended.
ogy. Some solutions that are effective for flotation
testing of other parasite eggs are not effective. Prognosis
A saturated sucrose solution (450 g in 350 ml water) Simple infestation with tapeworms carries an excel-
has been reported to be more effective. A. perfoli- lent prognosis because of the ease of treatment
ata eggs are D-shaped with a thick shell. The poor and limited clinical signs. The prognosis is poorer
sensitivity of faecal flotation has led to serological if a tapeworm-associated intestinal accident has
assays being evaluated, but these are more useful occurred.

DISORDERS OF THE LARGE COLON

COLITIS Salmonellosis
Salmonellosis occurs when the appropriate combi-
Definition/overview nation of host (immune status, GI microflora, pain),
Acute colitis is a potentially life-threatening disease bacterial (pathogenicity, dose) and environmental
characterised by diarrhoea and varying degrees of (stressors) factors is present. Faecal–oral inocula-
depression, dehydration, toxaemia, abdominal dis- tion or proliferation of small numbers of Salmonella
tension and abdominal pain. organisms already in the GI tract may occur. Large
numbers of organisms are typically required to cause
Aetiology/pathophysiology disease in normal animals. Compromised animals
A variety of pathogenic organisms may be involved, (young, concurrently ill, antimicrobial treated, hos-
including C. difficile, C. perfringens, Salmonella pitalised) may be infected with much lower num-
spp. and Neorickettsia risticii (Potomac horse fever bers. Certain Salmonella strains may be able to cause
[PHF]). Identification of the aetiological agent disease with lower numbers (Fig. 4.161).
can be difficult because of limitations of avail-
able tests and incomplete understanding of the GI Clostridium difficile infection
microflora. In most regions, the majority of cases C. difficile is a spore-forming bacterium that can be
are idiopathic. Outbreaks of colitis can occur, found in a small percentage of normal horses, partic-
particularly in equine hospitals and on breeding ularly young horses and those treated with antimi-
farms. crobials. In some situations, C. difficile can proliferate