Page 297 - Problem-Based Feline Medicine

16 – THE CAT WITH ACUTE DEPRESSION, ANOREXIA OR DEHYDRATION 289

Treatment during therapy. Observe very closely for life-
threatening respiratory depression, which should
Immediate induction of emesis and activated char-
prompt reduction of ethanol treatmet. Monitor
coal or gastric lavage if ingestion is witnessed.
body temperature and rewarm if hypothermia
Ethylene glycol is rapidly absorbed and intestinal
develops.
decontamination is unlikely to be of any benefit after
● Ideally monitor acid-base status. If pH < 7.25
two hours or once clinical signs have appeared. –
and/or HCO < 8 mmol/L, give NaHCO (mmol =
3 3
Prevent ethylene glycol metabolism. This may be 0.2 × kg × base deficit) over 4 hours IV. Repeat as
achieved using either ethanol or fomepizole as compet- necessary.
itive inhibitors of alcohol dehydrogenase. Treatment ● If intravenous therapy is not possible, give the
must be initiated within 3 hours of ingestion to prevent ethanol doses above intraperitoneally, and addi-
acute renal failure. The unmetabolized ethylene glycol tional fluids subcutaneously.
is eliminated via the kidneys. – If the cat cannot be hospitalized immediately for
● Cats are usually treated with ethanol; several pro- ethanol therapy, the owner can attempt to give a
tocols exist. Prepare 20% (20 g/100 ml, 200 mg/ml) 40% alcoholic beverage by mouth (e.g. rum,
ethanol my mixing 1 part of 95–100% ethanol with vodka), 2.5 ml/kg, although a cat is less likely to
4 parts saline. (An alternative is to mix 1 part vodka tolerate this than a dog.
[40% ethanol] with 1 part saline.) Give 3 ml/kg 20% ● Fomepizole (4-methylpyrazole) is the treatment of
ethanol (600 mg/kg) over 1 hour further diluted to a choice in dogs. The drug causes minimal central
minimum of 1 part 20% solution and 2 parts saline nervous system depression and does not increase
for a final ≈7% maximum concentration solution. serum osmolality or metabolic acidosis. Although
(Additional dilution is needed in these protocols as initially considered ineffective in cats, recent stud-
the ethanol solutions are hyperosmolar). This is fol- ies suggest that higher doses are effective.
lowed by a constant rate infusion of 20% ethanol, – Give 125 mg/kg 5% solution IV initial dose, fol-
0.5 ml/kg/hr (100 mg/kg/hr), in a minimum of lowed by 31.25 mg/kg IV at 12, 24 and 36 hours
2 ml/kg/hr saline (again for a final ≈7% maximum post-ingestion. The dose should be given over
concentration). (The dose may be increased with 15–30 minutes.
close monitoring up to 1.0 ml [200 mg]/kg/hr in
Multiple B-vitamins containing pyridoxine and thi-
4 ml/kg/hr fluids.) Treatment is continued for 10
amine may enhance the metabolism of glyoxylic acid
hours after a negative serum ethylene glycol test, or
to non-toxic metabolites and protect the nervous system
18 hours after correction of metabolic acidosis
during ethanol therapy. Compatability of B-vitamins
without ongoing need for NaHCO treatment. An
3 with ethanol solutions is not known, so administration
alternative protocol is to give 5 mL/kg 20% ethanol,
via a separate IV line is recommended.
diluted into IV fluids, by constant rate infusion over
6 hours for 5 treatments, then over 8 hours for 4 See Acute renal failure, above.
treatments. (The serum half-life of ethylene glycol ● Most ingestion is not witnessed, and, without dial-
for cats receiving ethanol is 29 hours.) ysis, the prognosis for cats with oliguric or anuric
● Begin IV fluids (do not use Ringer’s or lactated renal failure is grave. Hemodialysis has been used
Ringer’s) at 1.5–3 times maintenance based on successfully to support cats through oliguric and
patient requirements and adjusted to account for anuric renal failure until tubular regeneration
volume delivered with ethanol solutions. Monitor occurred. Peritoneal dialysis may be considered,
hydration status, body weight, and urine output; especially if oliguria has not progressed to anuria,
observe respiration and auscultate lungs frequently as the chances for recovery of renal function are
to monitor for pulmonary edema. perhaps somewhat better with oliguria than with
● Ideally measure serum ethanol concentrations anuria.
and maintain at 100 mg/dL. Treatment will ● Renal transplantation may be considered in cats
increase central nervous system depression and with oliguric or anuric renal failure.
serum osmolality. The cat may become comatose