A muscle relaxant, methocarbamol for dogs is primarily used to stop involuntary movement of muscles, commonly associated with exposure to toxic substances. Methocarbamol Side Effects and Risks While this drug is generally very safe for most dogs, there are situations in which the medicine should be avoided. If your pet suffers from any type of kidney damage, this medicine can be dangerous. Methocarbamol is a leading USA FDA approved prescription based muscle-relaxant for use in dogs. It helps dogs suffering from muscle-spasms, twitching, & more. Some of the common side effects of Methocarbamol in dogs and cats include drooling, sedation, emesis, muscular weakness and vomiting, which usually should subside in a few days. If symptoms persist, consult the veterinarian without any delay. Consumer information about the medication methocarbamol (Robaxin, Robaxin-750), includes side effects, drug interactions, recommended dosages, and storage information. Read more about the prescription drug methocarbamol (Robaxin, Robaxin-750). Methocarbamol is a muscle relaxant. It works by blocking nerve impulses (or pain sensations) that are sent to your brain. Methocarbamol is used together with rest and physical therapy to treat skeletal muscle conditions such as pain or injury. Find patient medical information for Methocarbamol Oral on WebMD including its uses, side effects and safety, interactions, pictures, warnings and user ratings. Along with its needed effects, methocarbamol may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention. Although not all of these side effects may occur, if they do occur they may need medical attention. Methocarbamol is a muscle relaxant that is certified and approved by the US FDA for use in dogs as well as other pets and livestock whenever appropriate. Side effects that can occur in dogs and cats may include weakness, stumbling, incoordination, drooling, and vomiting. Methocarbamol may discolor the urine. Talk to your veterinarian about any side effect that seems unusual or bothersome to the animal.