Page 709 - Problem-Based Feline Medicine

32 – THE CAT WITH SIGNS OF ACUTE SMALL BOWEL DIARRHEA 701

● Heavy metals (lead, arsenic) (p 724)
The two most common heavy metal intoxications are ingestion of lead and arsenic. Both cause
severe GI signs: vomiting, diarrhea, anorexia, and depression, but lead poisoning will progress to
neurologic signs (e.g. ataxia, tremors and seizures), while arsenic is nephrotoxic and hepatotoxic.

● Plant ingestion/toxicity (p 728)
Plants may irritate mucous membranes and cause acute drooling, vomiting or diarrhea. Plant tox-
ins that result in renal or hepatic failure may cause more severe and prolonged vomiting, diarrhea,
depression and anorexia.

Increased secretion of water and electrolytes is
INTRODUCTION
another cause of diarrhea which occurs primarily as
a result of activation of cellular second messenger path-
ways (cAMP, cGMP, etc). The causes of secretory
MECHANISM?
diarrhea in cats include Salmonella, Clostridium,
Acute small intestinal diarrhea is a common clinical Campylobacter, E. coli, and Staphylococcus. Diarrhea
problem that is often mild or self-limiting. due to hyperthryoidism may also be due to a secretory
mechanism, but this is unproven.
In general, small bowel diarrhea tends to be milder in
cats than in dogs because of the capacity of the feline The presence of increased intestinal permeability
GI tract to absorb water. due to inflammation, erosion/ulceration or necrosis
is also an important cause of diarrhea. A major cause of
Some diseases which typically produce chronic diar-
increased permeability diarrhea in cats is IBD, but
rhea may present as acute diarrhea.
lymphoma or other causes of intestinal inflammation,
In some cats, life-threatening illness develops due to such as the enteroinvasive bacteria (e.g. E. coli) can
the severity of fluid loss or as a result of the primary also cause diarrhea by this mechanism.
problem causing the small bowel diarrhea (endotoxe-
Altered intestinal motility, either increased or
mia, neoplasia, etc.).
decreased segmentation or propulsion movements will
There are many different causes of diarrhea, which lit- cause diarrhea. While it is difficult to prove that altered
erally is the presence of increased water in the feces. motility is the primary cause of diarrhea in many cases,
it may occur in hyperthyroidism, dysautonomia, some
The increase in fecal water may be due to a physical,
infectious enteropathies and in GI neoplasia.
functional or physiologic disturbance in the small intes-
tine, the colon, or both. The main consequences of acute small bowel diar-
rhea are dehydration and development of metabolic
Characteristics of small bowel diarrhea include:
acidosis as a result of fluid and electrolyte losses.
● A large volume of watery or very soft feces.
● No mucus or hematochezia, if blood is present it Infectious and parasitic causes of small intestinal
occurs as melena. diarrhea may be either self-limiting or severe, depend-
● There is little or no straining or tenesmus. ing on the pathogenicity of the organism.
● Weight loss and vomiting are commonly observed.
Inflammatory bowel disease, neoplasia and other more
● The frequency of defecation is normal to increased.
severe diseases that cause small bowel diarrhea are often
Diarrhea may be due to increased osmotically active associated with other signs of systemic or GI disease,
substances present in the lumen. The most common such as weight loss, anorexia, vomiting or depression.
causes of this type of diarrhea are dietary
overload/indiscretion and malabsorption, which can
WHERE?
be due to deficiency of pancreatic (e.g. EPI) or intestinal
brush border enzymes, or upper small bowel diseases Small bowel diarrhea can be the result of disease in the
(e.g. mucosal or intramural), such as IBD or lymphoma. small intestine (duodenum, jejunum, ileum) or occur