Page 295 - Problem-Based Feline Medicine

16 – THE CAT WITH ACUTE DEPRESSION, ANOREXIA OR DEHYDRATION 287

● Cholecalciferol rodenticide – treatment of hyper- It tastes sweet to humans, and is palatable to cats. The
calcemia (saline, furosemide, calcitonin, pred- minimum lethal dose of undiluted ethylene glycol in
nisone, ± biphosphonates). cats is only 1.4 ml/kg.
● Organophosphates and carbamates – atropine
Ethylene glycol is rapidly absorbed from the intes-
(both), pralidoxime chloride (organophosphates
tinal tract.
only).
● Peak plasma concentration is achieved 1 hour
● Acetaminophen – acetylcysteine, ascorbic acid,
post ingestion in a fasted cat. Food probably delays
transfusion (see page 596, The Cat With Salivation).
peak plasma concentrations, but by at most 1–2
● Aspirin and NSAIDs – Treatment of gastric ulcera-
hours.
tion (H2 blockers, sulcralfate), treatment of acute
renal injury with fluids. Following absorption, ethylene glycol is excreted
● Lilies – see separate heading below. about 50% unchanged in the urine (peak urine con-
● Lead – CaNa EDTA, D-penicillamine (contraindi- centration is achieved at 6 hours). Some passive reab-
2
cated if lead present in intestinal tract), succimer sorption occurs in the distal convoluted tubules and
(preferred treatment). collecting ducts. The other 50% is metabolized in
● Ethylene glycol – see separate heading below. the liver by alcohol dehydrogenase to glycoaldehyde,
● Venlafaxine – cyproheptadine 2–4 mg/cat PO or per which in turn is metabolized by aldehyde dehydroge-
rectum may counteract serotonin effects. nase to glycolic acid. Glycolic acid is further metabo-
● Ixodid tick paralysis and Lactrodectus spider lized to glyoxylic acid, which is then metabolized to
bites – specific antivenin (see pages 954, 975, The final metabolites including oxalic acid. Oxalic acid
Cat With Generalized Weakness). combines with calcium to form calcium oxalate crys-
tals. The serum half-life of ethylene glycol in
Treat arrhythmias, e.g. atropine for daffodil-induced
untreated cats is 2–5 hours.
bradycardia (see page 160, The Cat With Tachycardia,
● Acute tubular necrosis is caused by cytotoxic effects
Bradycardia or an Irregular Rhythm).
of glycolic, glyoxalic and oxalic acids. Deposition
Treat tremors and seizures – diazepam, methocarbamol, of crystals in the kidneys has a minor role.
phenobarbital, pentobarbital (see page 801, The Cat
With Seizures, Circling, and/or Changed Behavior).
Beware of hypothermia following correction of hyperther- Clinical signs
mia, which may cause renewed tremors.
Signs of acute ethylene glycol poisoning (<12 hours)
Treat agitation – consider acepromazine (ensure cat is are due to direct effects of the poison and metabolites
not hypotensive). on the central nervous system and gastrointestinal
tract, and include depression, ataxia, tremors, vom-
Supportive care.
iting, and a sweet odor to the breath. Polyuria
occurs due to osmotic diuresis. Polydipsia is uncom-
mon in cats.
ETHYLENE GLYCOL POISONING*
Later signs (> 12 hours) are due to acute renal failure
Classical signs and include progressive depression, anorexia, oral ulcer-
ation, hypothermia, painful and swollen kidneys,
● Acute depression and anorexia.
seizures, oliguria and anuria.
Pathogenesis
Diagnosis
Ethylene glycol is a solvent used in paints, polishes,
inks and antifreeze, which is the most common source The diagnosis of acute poisoning relies on history of
of poisoning. It is a colorless liquid – the yellow-green ingestion or a high index of suspicion.
appearance of antifreeze is due to the addition of fluo- ● Acute ethylene glycol poisoning should be consid-
rescein. ered in any cat at risk with acute depression.