Page 575 - Problem-Based Feline Medicine

25 – THE CAT WITH POLYCYTHEMIA 567

protocol), supplemental O and intravenous high-dose
Clinical signs 2
prednisolone sodium succinate (100 mg/cat IV). The
Clinical signs of acute systemic anaphylaxis vary rate of fluid administration should be as rapid as possi-
between species, as the major organs affected in the ble to restore circulating blood volume. In cats, 150 ml
reaction are species-specific. can be given rapidly in the first hour but additional flu-
ids should be administered more slowly to prevent pul-
Since the “shock organ” in the cat is the lung, pul-
monary edema. Fluid therapy may be evaluated by
monary signs such as severe acute dyspnea predominate.
monitoring blood pressure, packed cell volume and
Signs of hypotensive shock, such as pallor and col- urine output.
lapse, accompany the pulmonary signs.
Adjunctive therapy with bronchodilating agents
The onset of clinical signs occurs in seconds to min- (epinephrine 0.2 ml/cat of a 1:1000 dilution IV;
utes after exposure to the inciting antigen. terbutaline 0.1 mg/kg SC or IV) and antihistamines
(chlorpheniramine maleate 1 mg/kg SC) may also be
Occasionally, cutaneous swelling may be noted around
used.
the face and paws.
Prognosis
Diagnosis
Since acute systemic anaphylaxis is such an acute,
Polycythemia may be evident on hematological exam-
overwhelming and life-threatening condition, the prog-
ination. Typically, mucus membranes are pale and
nosis is guarded to poor, depending on how promptly
signs are peracute. This is in contrast to other causes of
and aggressively therapy is initiated, and perhaps on the
polycythemia where mucous membranes are dark pink
amount of inciting antigen to which the cat was
and there are often signs suggesting chronic disease
exposed and the rapidity of exposure.
such as weight loss. Diagnosis is made by a combina-
tion of appropriate history and characteristic clini-
cal signs. STRESS-INDUCED SPLENIC
CONTRACTION
No laboratory tests are currently available to make
a definitive diagnosis of acute systemic anaphylaxis.
Classical signs
Blood O saturation is acutely and severely reduced.
2
● The stress response in cats may include
splenic contraction, with a resultant
Differential diagnosis infusion of stored splenic erythrocytes into
the circulation.
Polycythemia associated with anaphylaxis is usually
● Hemoconcentration caused by stress is
readily distinguishable from all other causes of poly-
usually mild and transient.
cythemia due to its peracute onset. Accompanying clin-
ical signs differentiate it from dehydration, which is
associated with more chronic signs including anorexia Diagnosis
and depression.
Affected cats often have an appropriate history of acute
Acute systemic anaphylaxis must be differentiated from stress. This may be stress associated with surgery or
other causes of acute shock such as major trauma. other treatment, as well as the flight-or-fight response
to acute stress.
Treatment There may be associated signs of acute stress such as
dilated pupils and behavioral changes.
Acute shock caused by anaphylaxis should be treated
by a combination of intravenous fluid therapy at Erythrocytosis should resolve promptly after the incit-
shock dose rates (perhaps including colloids in the ing incident.