Table of Contents 23 sections Group Mechanism of Action Dose Rates Dog Cat Horse Cattle Sheep Goat Pig Ferret Rabbit Mouse Rat Gerbil Hamster Guinea pig Indications Contraindications Interactions Adverse effects Toxicity Preparations
Aspirin Aspirin provides analgesic, anti-inflammatory and antiplatelet effects, but GI toxicity and variable platelet inhibition limit its veterinary use. Cats eliminate salicylate slowly.
Salicylate NSAID; antiplatelet
Irreversible cyclooxygenase acetylation suppresses platelet thromboxane synthesis; prostaglandin inhibition also contributes to analgesia, inflammation control and GI or renal adverse effects.
Dog Use / stage Dose Route Schedule Instructions Mild analgesia 10 mg/kg PO Every 12 h Prefer immediate-release preparations; enteric-coated products have erratic absorption in dogs. Anti-inflammatory treatment 20–25 mg/kg PO Every 12 h GI injury can occur even within this dose range. Antiplatelet treatment 1–5 mg/kg PO Every 24 h Platelet response and clinical benefit are inconsistent; titration requires a defined thrombotic-risk indication. Anti-inflammatory treatment 25 mg/kg PO Every 8 h Older anti-inflammatory schedule; GI bleeding risk increases with exposure. Antipyresis 10 mg/kg PO Every 12 h IMHA-associated thromboprophylaxis 0.5 mg/kg PO Every 12 h Adjunctive low-dose regimen; evaluate bleeding risk and concurrent immunosuppressants. IMHA-associated thromboprophylaxis 0.5 mg/kg PO Every 24 h Alternative once-daily adjunctive regimen; do not combine with the twice-daily schedule. Glomerular disease-associated thromboprophylaxis 0.5 mg/kg PO Every 24 h
Cat Use / stage Dose Route Schedule Instructions Mild analgesia 10 mg/kg PO Every 48 h Slow feline salicylate clearance increases accumulation risk; alternative analgesics are generally preferable. Anti-inflammatory treatment 10–20 mg/kg PO Every 48 h Historical regimen with a narrow safety margin; assess alternatives and monitor closely. Antiplatelet treatment 81 mg/animal PO Every 72 h Alternative antiplatelet agents are often preferred; efficacy is less consistent than with clopidogrel. Mild analgesia 10 mg/kg PO Every 48–72 h Alternative prolonged interval; give with food and monitor for accumulation. Arterial thromboembolism prevention 5 mg/animal PO Every 72 h Alternative antiplatelet drugs may provide better protection; monitor for bleeding. Arterial thromboembolism prevention 40 mg/animal PO Every 72 h Older fixed-dose alternative; not additive to low-dose aspirin.
Horse Use / stage Dose Route Schedule Instructions Pain and inflammation 25–50 mg/kg PO Every 12 h Do not exceed 100 mg/kg over 24 hours; monitor GI tolerance and bleeding. Pain and inflammation — Initial 25 mg/kg PO Every 12 h Follow with the lower daily maintenance amount. Pain and inflammation — Maintenance 10 mg/kg PO Every 24 h Pain and inflammation 15–100 mg/kg PO Every 24 h Alternative historical daily regimen; not additive to the twice-daily schedule. Laminitis-associated antiplatelet treatment 5–10 mg/kg PO Every 24–48 h Adjunctive antiplatelet approach; does not replace primary laminitis management. Laminitis-associated antiplatelet treatment 20 mg/kg PO Every 96–120 h Alternative intermittent regimen; not additive to daily dosing.
Cattle Use / stage Dose Route Schedule Instructions Pain and inflammation 100 mg/kg PO Every 12 h Historical ruminant regimen; food-animal residue restrictions depend on the actual product and use.
Sheep Use / stage Dose Route Schedule Instructions Pain and inflammation 100 mg/kg PO Every 12 h Historical ruminant regimen; food-animal residue restrictions depend on the actual product and use.
Goat Use / stage Dose Route Schedule Instructions Pain and inflammation 100 mg/kg PO Every 12 h Historical ruminant regimen; food-animal residue restrictions depend on the actual product and use.
Pig Use / stage Dose Route Schedule Instructions Pain and inflammation 10 mg/kg PO Every 6–8 h Pain and inflammation 10 mg/kg PO Every 4 h
Ferret Use / stage Dose Route Schedule Instructions Mild analgesia 10–20 mg/kg PO Every 24 h
Rabbit Use / stage Dose Route Schedule Instructions Mild analgesia 5–20 mg/kg PO Every 24 h
Mouse Use / stage Dose Route Schedule Instructions Mild analgesia 100–150 mg/kg PO Every 4 h Species-specific historical regimen; do not extrapolate to cats or other small mammals.
Rat Use / stage Dose Route Schedule Instructions Mild analgesia 100–150 mg/kg PO Every 4 h Species-specific historical regimen; do not extrapolate to cats or other small mammals.
Gerbil Use / stage Dose Route Schedule Instructions Mild analgesia 100–150 mg/kg PO Every 4 h Species-specific historical regimen; do not extrapolate to cats or other small mammals.
Hamster Use / stage Dose Route Schedule Instructions Mild analgesia 100–150 mg/kg PO Every 4 h Species-specific historical regimen; do not extrapolate to cats or other small mammals.
Guinea pig Use / stage Dose Route Schedule Instructions Mild analgesia 87 mg/kg PO Repeat interval is not specified.
Selected mild pain or inflammatory conditions. Antiplatelet treatment when chosen for a specific thrombotic risk; response is variable and clopidogrel is often more effective. Not supported as routine prevention of heartworm-associated thromboembolic complications. Selected antiplatelet adjuncts in IMHA, glomerular disease and laminitis; species-specific historical analgesic or antipyretic uses. GI ulceration or GI bleeding. Bleeding disorders or clinically important coagulopathy. Dehydration or significant renal compromise. Avoid routine concurrent NSAIDs or corticosteroids; any specifically selected low-dose antithrombotic combination requires an explicit bleeding-risk assessment. Hypoalbuminemia can increase unbound salicylate exposure; assess whether dose reduction is needed. Neonates and animals with severe hepatic dysfunction require particular caution. Avoid during pregnancy, especially near term, because salicylates may affect fetal development and delay parturition. Corticosteroids and other NSAIDs increase GI ulceration and bleeding. Anticoagulants and other antiplatelet drugs increase bleeding risk. Digoxin exposure may increase; furosemide can delay salicylate excretion. Methotrexate toxicity may increase through protein-binding and clearance effects. Urinary acidifiers reduce salicylate elimination. Urinary alkalinization increases elimination, but carbonic anhydrase inhibitors can simultaneously produce systemic acidosis and worsen CNS exposure. Phenobarbital may increase aspirin metabolism; aspirin can reduce spironolactone diuresis and antagonize uricosurics. Mineral buffers can chelate tetracyclines; separate administration. Aminoglycosides may add renal risk. Vomiting, gastric erosion, ulceration and melena. Impaired platelet function and bleeding. Renal injury in susceptible patients. Salicylate accumulation, especially in cats. Overdose may cause mixed acid–base disturbances, hemorrhage, hyperthermia, seizures and coma. Monitor GI signs, hydration, renal indices and bleeding; feline dosing requires long intervals. For planned surgery, review the need to interrupt aspirin in advance because platelet effects outlast circulating drug. The balance between bleeding and thrombosis determines the individual plan. Assess PCV and evidence of occult GI blood loss when indicated. Salicylates can interfere with urine glucose, ketone and catecholamine-metabolite assays and lower measured total T4.
Preparation Form Strength Route Bayer chewable aspirin 81 mg Tablet 81 mg / tablet PO Genuine Bayer Aspirin 325 mg Tablet 325 mg / tablet PO
