Published dose range
The published veterinary reference range for cetirizine in dogs is 0.5-1 mg per kg of body weight, given every 24h. In practice: 10 mg per dog daily (5 mg under 10 lbs).
Source: Veterinary Partner (VIN) →Plain cetirizine ONLY. Zyrtec-D is toxic.
Skip it or ask a vet first if
Zyrtec-D / decongestant versionskidney disease
If you think you overdosed
Call the Pet Poison Helpline: 855-764-7661 or ASPCA Poison Control: 888-426-4435. Both are staffed 24/7 by veterinary toxicologists.