From Dog

Diphenhydramine is a first-generation antihistamine possessing anticholinergic, antitussive and antiemetic properties.

This drug has the above advantages of most antihistamines though does not induce sedation in dogs[1].

Diphenhydramine is used for a variety of purposes in canine medicine, including:

Use of this drug is not recommended in dogs with keratoconjunctivitis sicca or glaucoma[7].

Recommended dose rate is 1.5 - 2.2 mg/kg orally or parenterally every 12 hours.


  1. Hofmeister EH & Egger CM (2005) Evaluation of diphenhydramine as a sedative for dogs. J Am Vet Med Assoc 226(7):1092-1094
  2. Simon D et al (2006) Postoperative adjuvant treatment of invasive malignant mammary gland tumors in dogs with doxorubicin and docetaxel. J Vet Intern Med 20(5):1184-1190
  3. Iwasaki T & Hasegawa A (2006) A randomized comparative clinical trial of recombinant canine interferon-gamma (KT-100) in atopic dogs using antihistamine as control. Vet Dermatol 17(3):195-200
  4. McCown JL et al (2009) Effect of antivenin dose on outcome from crotalid envenomation: 218 dogs (1988-2006). J Vet Emerg Crit Care (San Antonio) 19(6):603-610
  5. Carlsten KS et al (2012) Multicenter prospective trial of hypofractionated radiation treatment, toceranib, and prednisone for measurable canine mast cell tumors. J Vet Intern Med 26(1):135-141
  6. Brunnert SR et al (1992) Gastric extramedullary plasmacytoma in a dog. J Am Vet Med Assoc 200(10):1501-1502
  7. Evans PM et al (2012) Effects of oral administration of diphenhydramine on pupil diameter, intraocular pressure, tear production, tear film quality, conjunctival goblet cell density, and corneal sensitivity of clinically normal adult dogs. Am J Vet Res 73(12):1983-1986