Benzocaine, a topical anesthetic, is a popular medicine commonly used in veterinary applications. While benzocaine is generally recognized as safe for use in dogs, it rare cases in may cause serious reactions.
Veterinarians, pet guardians and dog groomers use benzocaine as a topical treatment for gum inflammation, skin disease and trauma-related pain.
In some sensitive dogs, benzocaine can cause a rash at the site where it is applied. This reaction is fairly common and mild; it is not a sign of a significant problem.
The Journal of the American Medical Association published a case report of three dogs who acquired methemoglobinemia--a serious blood disease--after their owners applied human-grade benzocaine to skin rashes. This complication is extremely rare and has not been reported in peer-reviewed literature since 1979.
Some dogs may experience a serious allergic reaction to benzocaine, especially if it has been ingested. Symptoms of a serious allergic reaction include vomiting, wheezing and lethargy.
While benzocaine may help relieve local pain and inflammation, it is ineffective and possibly dangerous when taken internally. Dog owners should monitor their pets to prevent them from ingesting benzocaine.