Aspirin (Acetylsalicyclic acid)

Aspirin (Acetylsalicylic acid) : Uses, Dosage, and Side Effects

Overview

Acetylsalicylic acid produces irreversible inhibition of cyclo-oxygenase (COX-1, prostaglandin synthetase) by acetylation, thereby preventing the production of both prostaglandins and thromboxanes from membrane phospholipids.

Uses of Aspirin (Acetylsalicylic acid)

• Prevention of arterial thromboembolism.
• Also can be used to control mild to moderate pain, although NSAIDs that are more selective for the COX-2 enzyme have a better safety profile; not an NSAID of choice for analgesia in dogs or cats.

Dose of Aspirin (Acetylsalicylic acid) in Dogs and Cats

Dogs: ( Doses are anecdotal and the ideal doses are unknown.)

• Reduction of platelet aggregation (e.g. IMHA): 0.5–1 mg/kg p.o. q24h or 0.5 mg/kg p.o. q12h.
• Analgesia, pyrexia, inflammation: doses range from 10 mg/kg to 20 mg/kg p.o. q12h.

Cats:

• Reduction of platelet aggregation:
• ¼ of a 75 mg tablet (18.75 mg) p.o for an average-sized cat 3 days a week (low dose) or, alternatively, 75 mg for an average-sized cat 3 days a week (high dose); this dose may be associated with a higher risk of GI side effects.
• Some authors suggest a very low dose (0.5 mg/kg p.o. q24h) to inhibit platelet COX without preventing the beneficial effects of prostacyclin production.

Side Effects of Aspirin (Acetylsalicylic acid) in Dogs and Cats

• GI ulceration and irritation are common side effects of all NSAIDs.
• All NSAIDs carry a risk of renal papillary necrosis due to reduced renal perfusion caused by a reduction in the production of renal prostaglandins. This risk is greatest when NSAIDs are given to animals that are hypotensive or animals with pre-existing renal disease.

Contraindications of Aspirin (Acetylsalicylic acid) in Dogs and Cats

• Do not give aspirin to dehydrated, hypovolaemic or hypotensive patients, or those with GI disease.
• Do not give to pregnant animals or animals <6 weeks old.

Some Notes:

• Recent evidence suggests that clopidogrel may be superior to aspirin in cats for the prevention of the recurrence of cardiogenic thromboembolic events.