Page 512 - Problem-Based Feline Medicine

504 PART 7 SICK CAT WITH SPECIFIC SIGNS

– Clinical reports of Massassauga rattlesnake bites Treatment
to cats are lacking. In dogs envenomation may
Keep animal calm.
cause marked prolongation of clotting times but
clinical bleeding is rare. If a bite on a limb is witnessed, application of a tourniquet
or cold pack by the owner for 10–20 min may be benefi-
Venoms from most Colubridae are mild and clinical
cial, but should not delay transport to a veterinarian.
reports of bites to cats lacking.
● The boomslang of central and South Africa pro- Supportive care.
duces a powerful hematoxin that is procoagulant
Specific antivenom (antivenin) therapy.
and causes DIC in humans and dogs.
● Observe for allergic reactions.
● Premedication with an anti-histamine, e.g. diphenhy-
Diagnosis dramine, 1 mg/kg IV as a slow bolus over 10–15 min
is recommended. This will not potentiate the venom.
Diagnosis is based on a history of exposure to the snake
(try to identify species) and/or physical examination If there are signs of hemostatic abnormalities, treat as
findings. for DIC (page 502) (see Disseminated intravascular
coagulation, above) with transfusions of fresh whole
CBC may reveal hemoconcentration, hemolysis,
blood, fresh plasma or fresh-frozen plasma.
echinocytosis, rubricytosis or thrombocytopenia.
Antibiotic therapy for secondary wound infection and
Serum chemistry profile may reveal hypoproteinemia,
delayed surgical management of the wound may be
hypokalemia and elevated CK, ALT, urea and creati-
necessary.
nine levels.
Urinalysis may reveal myoglobinuria or hemoglobin- HAGEMAN TRAIT*
uria, and glucosuria.
Hemostatic testing may reveal variable thrombocy- Classical signs
topenia, prolonged PT and/or ACT, aPTT, and ● None.
increased FDPs (i.e. DIC).

A Snake Venom Detection Kit (CSL Limited, Pathogenesis
Australia) can be used for identification of the presence
and type of Australian snake venom. Testing is also Hageman trait refers to reduced synthesis, release or
available from commercial veterinary laboratories. function of factor XII (Hageman factor).
Urine is preferred over blood because of non-specific
Activation of factor XII to XIIa is the first step in the
binding with plasma proteins. A swab of the bite site is
intrinsic system. As previously noted, this does not
most accurate, but is rarely identifiable in cats with
appear to be an important mechanism for the initiation
bites from Australian snakes.
of coagulation in vivo.
Factor XII is involved in the conversion of plasmino-
Differential diagnosis gen to plasmin, which is responsible for clot dissolu-
tion (fibrinolysis).
See The Weak and Ataxic or Paralyzed Cat (page 952)
for differential diagnosis of neurologic signs. Factor XII is also involved in inflammation.
Differential diagnoses for the local reaction include
Clinical signs
angioedema from insect envenomation, animal bite
wounds, sharp and blunt trauma. Spontaneous bleeding does not occur.
Differential diagnoses for hemostatic abnormalities Prolonged ACT and aPTT are usually noted inciden-
include other causes of DIC. tally, e.g. when hemostasis is evaluated prior to biopsy.