Doses - NAPROXEN
Dogs: 
a) 5 mg/kg PO initially, then 1.2 - 2.8 mg/kg PO once daily (Frey and Rieh 1981) b) 1.1 mg/kg PO q12h (McConnell and Hughey 1987)
Horses: 
a) 5 mg/kg by slow IV, then 10 mg/kg PO (top dressed in feed) twice daily for up to 14days or 10 mg/kg PO (top dressed in feed) bid for up to 14 consecutive days. (Package Insert; Equiproxen® - Syntex Animal Health)
Monitoring Parameters -
Client Information - Notify veterinarian if symptoms of GI distress (anorexia, vomiting in dogs, diarrhea, black feces or blood in stool) occur, or if animal becomes depressed.
Dosage Forms/Preparations/FDA Approval Status/Withholding Times - Veterinary-Approved Products:
Naproxen 10% (100 mg/ml) Veterinary Solution for Injection; 2 gm vial with 19 ml vial ofsterile water for injection. Use entire contents immediately after reconstituting. Makes 20 ml of10% (100 mg/ml) solution.; Equiproxen® (Fort Dodge); (Rx) Approved for us in horses notintended for food.
Naproxen Veterinary Granules; Each 8 gram packet contains 4 grams of naproxen. Cartons of14 - 8 gram packets; Equiproxen® (Fort Dodge); (Rx) Approved for us in horses not intendedfor food.
Human-Approved Products:
Naproxen Oral tablets (scored) 250 mg, 375 mg, 500 mg; Naprosyn® (Syntex); Generic (Rx)Naproxen Oral Suspension 125 mg/5 ml in pints; Naprosyn® (Syntex); Generic (Rx)NARCOTIC (OPIATE) AGONIST ANALGESICS, PHARMACOLOGY OF
Receptors for opiate analgesics are found in high concentrations in the limbic system, spinal cord, thalamus, hypothalamus, striatum, and midbrain. They are also found in tissues such as thegastrointestinal tract, urinary tract, and in other smooth muscle.
Opiate receptors are further broken down into five main sub-groups. Mu receptors are foundprimarily in the pain regulating areas of the brain. They are thought to contribute to the analgesia, euphoria, respiratory depression, physical dependence, miosis, and hypothermic actions of opiates.
Kappa receptors are located primarily in the deep layers of the cerebral cortex and spinal cord.
They are responsible for analgesia, sedation and miosis. Sigma receptors are thought to beresponsible for the dysphoric effects (struggling, whining), hallucinations, respiratory and cardiacstimulation, and mydriatic effects of opiates. Delta receptors, located in the limbic areas of the CNSand epsilon receptors have also been described, but their actions have not been well explained at thistime.
The morphine-like agonists (morphine, meperidine, oxymorphone) have primary activity at the mureceptors, with some activity possible at the delta receptor. The primary pharmacologic effects ofthese agents include: analgesia, antitussive activity, respiratory depression, sedation, emesis, physicaldependence, and intestinal effects (constipation/defecation). Secondary pharmacologic effectsinclude: CNS: euphoria, sedation, & confusion. Cardiovascular: bradycardia due to central vagalstimulation, alpha-adrenergic receptors may be depressed resulting in peripheral vasodilation, decreased peripheral resistance, and baroreceptor inhibition. Orthostatic hypotension and syncopemay occur. Urinary: Increased bladder sphincter tone can induce urinary retention.
Various species may exhibit contradictory effects from these agents. For example, horses, cattle, swine, and cats may develop excitement after morphine injections and dogs may defecate aftermorphine. These effects are in contrast to the expected effects of sedation and constipation. Dogsand humans may develop miosis, while other species (especially cats) may develop mydriasis. Formore information see the individual monographs for each agent.