Page 605 - Problem-Based Feline Medicine

27 – THE CAT WITH SALIVATION 597

Clinical signs of acetylcholine and norepinephrine resulting in sus-
tained muscle spasm.
Usually in young cats.
The mechanism of severe pain at the bite site and
Vague, chronic gastrointestinal signs most common –
regions remote from the actual bitten area is not well
e.g. inanition, inappetance, poor growth, occasionally
understood.
diarrhea and vomiting.
CNS signs can occur in more severe cases and include Clinical signs
behavioral changes (depression, aggression, lethargy)
seizures and blindness. Initially, severe pain characterized by crying out.
Occasionally, intermittent ptyalism. Hyperexcitability, ataxia, muscle rigidity and spasm,
progressing to muscle weakness and collapse.
Prolonged, severe ptyalism, possibly due to pain.
Diagnosis
Death can occur from respiratory failure.
History of access to lead, e.g. old house renovation
(lead-based paint, dust from sanding).
Diagnosis
Blood lead greater than 0.4 ppm.
Clinical signs.
Treatment History of contact with latrodectus spider.
Chelation of lead with calcium disodium ethylene Laboratory evaluation not helpful.
diamine tetra-acetate (CaEDTA) 100 mg/kg SC daily in
four divided doses. Dilute CaEDTA to a concentration Treatment
of about 10 mg CaEDTA/ml with 5% dextrose solution
for 5 days. In severe cases, a further 5-day course can Latrodectus antivenine results in dramatic improve-
be given after a rest period of 5 days. ment of clinical signs if given in the acute phase of the
disease and good results can be achieved even if given
Relapses of clinical signs of lead poisoning are com-
24 hours after envenomation.
mon and are treated as they arise.
● Premedicate with antihistamine (chlorpheni-
ramine 2.5–5 mg IM or SC) and have epinephrine
SPIDER ENVENOMATION (2.5–5 μg/kg IV) on hand. Latrodectus antivenine is
prepared from the hyperimmune serum of horses.
Classical signs ● Dose of antivenine is 1 vial (500 units) given by
intramuscular injection.
● Ptyalism.
● In life-threatening situations the intravenous route
● Hyperexcitability.
can be used but the risk of anaphylaxis is greater.
● Ataxia, paralysis.
Muscle spasm can be controlled with small doses of
intravenous diazepam (0.2–0.5 mg/kg q 6 h), but
Pathogenesis
avoid respiratory depression.
Latrodectus spp. spiders include black widow (USA),
Supportive care includes intravenous fluids, corti-
red back spider (Australia) and katipo (New
sone and atropine (to control salivation).
Zealand).
Venom contains alpha-latroxin, a potent neuro-toxin.
Prognosis
The toxin opens cation-selective channels at the presy-
naptic nerve terminals, causing release of large amount Good with use of antivenine; guarded without.