If you have any reason to suspect your pet has ingested something toxic, please contact your veterinarian or one of the other resources listed:
ASPCA Animal Poison Control Center 24-hour hotline at (888) 426-4435
• Pet Poison Helpline® 24-hour animal poison control service at (855) 764-7661


Generic Name: Morphine
Brand Names: Avinza, Kadian, MS Contin, MSIR, Oramorph SR, Roxanol, Roxanol-T, Rms

Morphine, as well as other opiates and opioids, is commonly used in both human and veterinary practice to provide pain relief.

Drugs classified in this category include Percocet, Vicodin, hydrocodone, and fentanyl. It also includes illicit drugs such as heroin.


Though your pet may be prescribed opioids, it is important to note that these medications can be toxic if ingested in significant quantities. Never give your pet more medication than prescribed and always consult your veterinarian before altering your pet’s medication regimen.

Signs and symptoms of toxicity: depression and fatigue (dogs), excitation and aggressiveness (cats), involuntary muscle movements, seizures, increased production of saliva, vomiting, defecation (dogs), constipation (cats), changes in urination (dramatic increase or decrease), decreased heart rate, increased panting and dramatic changes in pupil size.

Toxic consumption:
In dogs, 210 mg/kg injected and 133 mg/kg given IV can be lethal. In cats, 40 mg/kg of injected morphine can be lethal.

Dogs: Morphine Lethal Consumption
Yorkie, Chihuahua
Pug, Boston Terrier, Poodle
Beagle, Scottish Terrier
Boxer, Cocker Spaniel
Retriever, German Shepherd
Great Dane, St. Bernard
1 – 10 lbs.
(0.45 – 4.6 kg)
11 – 25 lbs.
(5 – 11.4 kg)
26 – 40 lbs.
(11.8 – 18.2 kg)
41 – 70 lbs.
(18.6 – 31.8 kg)
71 – 90 lbs.
(32.3 – 40.9 kg)
91 – 110 lbs.
(41.4 – 50 kg)
dog1 dog2 dog3 dog4 dog7 dog6
Morphine (SQ) > 94 mg > 1049 mg > 2477 mg > 3905 mg > 6782 mg > 8693 mg
Morphine (IV) > 59 mg > 664 mg > 1569 mg > 2473 mg > 4295 mg > 5506 mg
Cats: Morphine Lethal Consumption
Most Cats Large Cats
1 – 10 lbs.
(0.45 – 4.6 kg)
11 – 25 lbs.
(5 – 11.4 kg)
cat1 fat cat
Morphine (SQ) > 17 mg > 199 mg

– Malouin A, Boiler M. Sedatives, muscle relaxants, and opiods toxicity. In: Silverstein DC, Hopper K, eds. Small Animal Critical Care Medicine. St. Louis: Elsevier, 2009; pp.350-356.
– Osweiler, G, et al. (2011). Blackwell’s five-minute veterinary consult clinical companion. Small Animal Toxicology. [Kindle version]. Retrieved from Amazon.com

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