Page 665 - Problem-Based Feline Medicine

30 – THE CAT WITH SIGNS OF ACUTE VOMITING 657

Pathogenesis Typically, the hematology and serum chemistry profile
will be normal with NSAIDs other than acetamino-
Cats are much more sensitive to the effects of
phen, unless the cat has severe erosions or ulcers that
NSAIDs because they have a reduced capacity to
have been bleeding. In those cases, anemia of blood loss
metabolize these drugs in their liver (poor glucuronyl
will be present, and in some cases can be quite dramatic.
transferase activity).
Cats may present in acute, oliguric or anuric renal
The adverse consequences of NSAID ingestion on the failure, and in these cats, severe azotemia, hyperphos-
gastrointestinal tract are due to multifactorial effects on phatemia, hyperkalemia and severe metabolic acidosis
the tissue, including direct toxicity to the epithelium, may be present.
increased back diffusion of acid, decreased synthesis of
prostaglandins, mucus and bicarbonate, decreased Confirmation of gastritis, gastric erosions or ulcers
mucosal blood flow and microvascular injury. requires imaging studies. The most definitive means
of diagnosis is via endoscopy whereby through both
Acetaminophen (paracetamol), which is an analgesic, visualization and histopathology the diagnosis can be
antipyretic drug sometimes included in the NSAID confirmed. Severe ulcers can also be visualized on
group, does not have the same toxic effects on the gas- contrast radiographs or via ultrasound.
trointestinal tract. In fact, the toxicity of acetamino-
phen in cats is very high, but the toxic effect is due to Differential diagnosis
the oxidant effects on red cells causing methemoglo-
binemia, hemolysis, Heinz body anemia and hepato- Other differentials to consider are acute pancreatitis,
toxicity. mechanical obstructions, infectious agents such as
Helicobacter that cause acute gastritis and acute gastri-
tis/gastric disease of other causes.
Clinical signs
Treatment
Cats that have ingested aspirin, ibuprofen or related
NSAIDs are likely to show acute signs of GI upset Stop further ingestion of NSAIDs, and remove as
which may include anorexia, vomiting (with or without much of the drug from the GI tract as possible
hematemesis), or abdominal pain. (lavage, induce vomiting, administer activated char-
coal). This is especially important if the ingestion was
Chronic ingestion of these drugs may result in inap- an accidental overdose and has occurred within the past
petence, vomiting or diarrhea (with or without 2–4 hours, although gastric lavage is most useful if per-
melena). formed within 1 hour of ingestion.
Acute overdoses of NSAIDs, especially ibuprofen, In cases where the signs of acute gastritis or gastric
naproxen, etc., may result in acute oliguric or anuric ulceration are associated with blood loss, a transfu-
renal failure. sion may be necessary. This is especially true if perfo-
ration has occurred and immediate surgical intervention
Cats that have ingested acetaminophen (paracetamol)
is necessary.
will have hypersalivation and vomiting early, fol-
lowed by development of cyanosis (methemoglobine- Treatment is non-specific, as with any gastritis or ulcer
mia) and facial pruritus within a few hours. Later, patient: administer histamine-2 blockers (ranitidine or
untreated cats may develop edema of the face and famotidine), mucosal cytoprotectants (sucralfate), and
paws, and will ultimately develop liver failure if they antiemetics (metoclopramide) if indicated. If the cat is
survive the initial toxicity. dehydrated from the vomiting episodes, fluid therapy
and possibly potassium supplementation will also be
indicated.
Diagnosis
Prognosis
History of ingestion and appropriate clinical signs
are usually enough to support NSAID-induced gastritis Good with appropriate therapy and aggressive manage-
or ulceration as the cause of the GI signs. ment unless there is gastric or duodenal perforation, or