Doxycycline is a tetracycline antibiotic which inhibits protein synthesis and alters the permeability of cytoplasmic membranes in bacterial cells. While it is not yet approved by the FDA except as a gel for treating periodontal disease (Doxirobe® gel), both the tablets and injectable solution are often prescribed by vets.

It is a common choice of antibiotic for use in dogs with azotemia as it can safely be given to those with impaired kidney function.

Recommended Dosage

Note: Do not give this medicine to your dog without seeing the vet for a prescription and diagnosis of symptoms.

A typical dosage of doxycycline for dogs is 1.4 – 2.3 mg/lb every 12 hours for 7 to 14 days. Dr. Drew recommends a higher dosage of 2.3 – 4.5 mg/lb every 12 to 24 hours for 10 or more days. Always follow the recommendation of your vet.

The following chart shows a dosage of 2.3 mg/lb.

Canine dosage of doxycycline

Other suggested doses specific to different conditions are listed below:

To treat…

Method of administration


ErhlichiosisOral2.3 – 4.5 mg/lb every 12 hours for 7 to 10 days
Lyme diseaseOral4.5 mg/lb once daily for 21 to 28 days
Rocky Mountain spotted fever (RMSF)Oral2.3 mg/lb every 12 hours
Salmon poisoningIV4.5 mg/lb twice daily for 10 or more days
Soft tissue infections or UTIsOral or IV2.2 – 5 mg/lb twice daily for 7 to 14 days

All injections should be given intravenously (into the bloodstream). Avoid intramuscular or subcutaneous injection.

Gel Formulation

Doxirobe® gel used to treat periodontal disease comes packaged as two syringes which should be mixed together before use. For detailed instructions regarding the use of the gel and the amount to use please visit Zoetis.

Example: Your vet could choose to treat a 40 lb dog with 100 mg per dose, which is equal to one 100 mg tablet per dose.

Is It Safe?

Doxycycline is FDA approved in gel form, and the oral/injectable forms are commonly used to treat dogs. Care must be taken to avoid superinfections of bacteria and fungi which are not susceptible to the drug. Rapid IV injection of the drug in overdose amounts could potentially lead to irregular heartbeat and more serious cardiac effects based on the reactions of other species.

Pregnancy/Nursing: Do not administer this medicine to pregnant or nursing dogs. If use on a pregnant dog is unavoidable, use of the medicine during the last half of pregnancy is possible.

Guidelines For Use

We recommend the following guidelines when using this medicine to treat your dog:

  • Do not use unless prescribed by a vet
  • Complete the course of treatment suggested by your vet
  • Administer with food

Do not administer this medicine orally alongside antacids. Doing so could inhibit the absorption of the medicine. Do not give to dogs who have shown hypersensitivity to this drug or any other tetracycline antibiotics in the past.


Doxycycline is an antibiotic, it can treat many different bacterial infections and is usually the drug of choice for treating Rocky Mountain Spotted Fever as well as several other tick-borne diseases.

Side Effects

Side effects are usually limited to gastric upset. Incidence of vomiting and nausea can be reduced significantly by administering the drug alongside food. In larger amounts weight loss has been noted. In rare cases superinfections may develop following the use of this medicine due to the growth of bacteria and fungi which are resistant to the drug.


Dr. Drew
Dr. K. Hartmann
Dr. Y. Rikihisa
Plumb’s Veterinary Drug Handbook (sixth edition)