Is Aspirin (acetylsalicylic acid) safe for dogs and cats?
Moderate risk for petsDogs are moderately sensitive to aspirin toxicity compared to cats, with a plasma half-life of approximately 7–8 hours and adequate glucuronidation capacity. The therapeutic dose range in dogs is 10–25 mg/kg every 12–24 hours, but the toxic threshold begins near 50 mg/kg with a single dose, and chronic dosing at therapeutic levels frequently causes gastrointestinal toxicity (gastric and intestinal ulceration, hemorrhage). Aspirin's mechanism of GI toxicity in dogs is two-fold: (1) direct irritation and erosion from salicylic acid, and (2) systemic COX-1 inhibition reducing mucosal prostaglandin production (PGE2, PGI2), impairing the gastric mucosal barrier. Dogs showing signs of salicylate toxicity present with vomiting (often with blood), diarrhea, abdominal pain, lethargy, hyperpnea, and in severe cases, seizures and renal failure. Over-the-counter aspirin products are frequently given by owners for pain management without veterinary guidance, making aspirin one of the most common causes of NSAID toxicosis in dogs. Safer alternatives (meloxicam, carprofen, deracoxib) exist under veterinary prescription.
What is aspirin (acetylsalicylic acid)?
The IUPAC name is 2-acetyloxybenzoic acid.
Also known as: 2-acetyloxybenzoic acid, aspirin, ACETYLSALICYLIC ACID, 2-Acetoxybenzoic acid.
- IUPAC name
- 2-acetyloxybenzoic acid
- CAS number
- 50-78-2
- Molecular formula
- C9H8O4
- Molecular weight
- 180.16 g/mol
- SMILES
- CC(=O)OC1=CC=CC=C1C(=O)O
- PubChem CID
- 2244
Risk for dogs
Moderate riskDogs are moderately sensitive to aspirin toxicity compared to cats, with a plasma half-life of approximately 7–8 hours and adequate glucuronidation capacity. The therapeutic dose range in dogs is 10–25 mg/kg every 12–24 hours, but the toxic threshold begins near 50 mg/kg with a single dose, and chronic dosing at therapeutic levels frequently causes gastrointestinal toxicity (gastric and intestinal ulceration, hemorrhage). Aspirin's mechanism of GI toxicity in dogs is two-fold: (1) direct irritation and erosion from salicylic acid, and (2) systemic COX-1 inhibition reducing mucosal prostaglandin production (PGE2, PGI2), impairing the gastric mucosal barrier. Dogs showing signs of salicylate toxicity present with vomiting (often with blood), diarrhea, abdominal pain, lethargy, hyperpnea, and in severe cases, seizures and renal failure. Over-the-counter aspirin products are frequently given by owners for pain management without veterinary guidance, making aspirin one of the most common causes of NSAID toxicosis in dogs. Safer alternatives (meloxicam, carprofen, deracoxib) exist under veterinary prescription.
Risk for cats
Extreme riskAspirin (acetylsalicylic acid) is extremely toxic to cats and must never be administered except under strict veterinary supervision at precisely controlled doses and intervals. Cats have severely limited capacity to glucuronidate (conjugate) salicylates due to a deficiency in UGT1A6 glucuronosyltransferase, the primary hepatic enzyme responsible for salicylate clearance in other species. A single regular-strength aspirin (325 mg) produces plasma salicylate levels that persist for 38–44 hours in cats compared to 7–8 hours in dogs and 3–5 hours in humans. This prolonged half-life leads to drug accumulation with repeat dosing. Toxic effects include gastric hemorrhage (prostaglandin-mediated mucosal erosion), metabolic acidosis, hyperthermia (uncoupled oxidative phosphorylation), CNS depression, and hepatic necrosis. Salicylate toxicosis is a significant cause of feline pharmaceutical poisoning presenting to veterinary emergency services. Baby aspirin (81 mg) has historically been used in cats for antiplatelet therapy in hypertrophic cardiomyopathy but only at 48-hour or 72-hour intervals under veterinary direction — this therapeutic use does not imply safety for ad hoc administration. ASPCA APCC classifies aspirin as a high-risk pharmaceutical toxin for cats.
Regulatory consensus
9 regulatory and scientific bodies have classified Aspirin (acetylsalicylic acid). The classifications differ — that's the data.
| Agency | Year | Classification | Notes |
|---|---|---|---|
| EPA CTX / Genetox | — | Genotoxicity: negative (Ames: negative, 0 positive / 3 negative reports) | |
| EPA CTX / Genetox | — | Genotoxicity: negative (Ames: negative, 0 positive / 3 negative reports) | |
| EPA CTX / Skin-Eye | — | Eye Irritation: Category 2A (score: high) | |
| EPA CTX / Skin-Eye | — | Skin Irritation: Not classified (score: low) | |
| EPA CTX / Skin-Eye | — | Eye Irritation: Category 6.4A (Category 2A) (score: high) | |
| EPA CTX / Skin-Eye | — | Skin Irritation: Category 6.3B (Category 3) (score: moderate) | |
| EPA CTX / Skin-Eye | — | skin sensitisation: in vivo (non-LLNA): Not likely to be sensitizing (score: low) | |
| EPA CTX / Skin-Eye | — | skin irritation: in vivo: Studies Indicate No Significant Irritation (score: low) | |
| EPA CTX / Skin-Eye | — | eye irritation: in vivo: Studies Indicate No Significant Irritation (score: low) |
Regulators apply different standards of evidence — animal-data weighting, exposure-pattern assumptions, epidemiological power thresholds — which is why two scientific bodies can review the same data and reach different conclusions. The disagreement is the data.
Where pets encounter aspirin (acetylsalicylic acid)
- Industrial Facilities — Manufacturing plants, Chemical storage areas, Waste treatment sites
- Occupational Environments — Factories, Warehouses, Transportation vehicles
Safer alternatives
Lower-risk approaches that achieve a similar outcome to Aspirin (acetylsalicylic acid):
-
Therapeutic alternatives (consult prescriber)
Trade-offs: Drug-specific. Cannot substitute without medical guidance.Relative cost: 1.2-2×
Frequently asked questions
Is aspirin (acetylsalicylic acid) safe for pets?
Dogs are moderately sensitive to aspirin toxicity compared to cats, with a plasma half-life of approximately 7–8 hours and adequate glucuronidation capacity. The therapeutic dose range in dogs is 10–25 mg/kg every 12–24 hours, but the toxic threshold begins near 50 mg/kg with a single dose, and chronic dosing at therapeutic levels frequently causes gastrointestinal toxicity (gastric and intestinal ulceration, hemorrhage). Aspirin's mechanism of GI toxicity in dogs is two-fold: (1) direct irritation and erosion from salicylic acid, and (2) systemic COX-1 inhibition reducing mucosal prostaglandin production (PGE2, PGI2), impairing the gastric mucosal barrier. Dogs showing signs of salicylate toxicity present with vomiting (often with blood), diarrhea, abdominal pain, lethargy, hyperpnea, and in severe cases, seizures and renal failure. Over-the-counter aspirin products are frequently given by owners for pain management without veterinary guidance, making aspirin one of the most common causes of NSAID toxicosis in dogs. Safer alternatives (meloxicam, carprofen, deracoxib) exist under veterinary prescription.
What products contain aspirin (acetylsalicylic acid)?
Aspirin (acetylsalicylic acid) appears in: Manufacturing plants (Industrial facilities); Chemical storage areas (Industrial facilities); Factories (Occupational environments); Warehouses (Occupational environments).
Why do regulators disagree about aspirin (acetylsalicylic acid)?
Aspirin (acetylsalicylic acid) has been classified by 9 agencies including EPA CTX / Genetox, EPA CTX / Genetox, EPA CTX / Skin-Eye, EPA CTX / Skin-Eye, EPA CTX / Skin-Eye, with differing conclusions. Regulators apply different standards of evidence (animal data weighting, exposure-pattern assumptions, epidemiological power thresholds), which is why two scientific bodies can review the same data and reach different conclusions. See the regulatory consensus table on this page for the full picture.
See Aspirin (acetylsalicylic acid) in the pets app
Look up products containing aspirin (acetylsalicylic acid), compare to alternatives, and explore the full data record.
Open in pets View raw API dataSources (4)
- US FDA: Aspirin (Acetylsalicylic Acid) OTC Drug Labeling, Reye's Syndrome Warning, and Antiplatelet Use Guidance (2020) — regulatory
- ASPCA Animal Poison Control Center: Aspirin and Salicylate Toxicosis in Dogs and Cats — Clinical Management and Risk Assessment (2023) — veterinary
- Plumb's Veterinary Drug Handbook (10th ed.) — Aspirin: Species-Specific Pharmacokinetics, Dosing, and Toxicity in Companion Animals (2023) — veterinary
- CDC: Reye's Syndrome — Epidemiology, Aspirin Association, and Public Health Response (2016) — regulatory
Reference data, not professional advice. Aggregates publicly available regulatory and scientific data; not a substitute for veterinary, medical, legal, or regulatory advice. Why we built ALETHEIA →