Medication Guide • Reviewed by Dr. Tiffany Delacruz, DVM
Doxycycline for Dogs
Doxycycline is a prescription antibiotic used to treat tick-borne diseases, respiratory infections, and certain skin and urinary infections in dogs.
What Doxycycline is used for in dogs
- Tick-borne illnesses (Lyme, ehrlichiosis, anaplasmosis, Rocky Mountain spotted fever)
- Respiratory infections
- Some skin infections
- Urinary tract infections
- Heartworm treatment protocol (adjunctive)
How it works
Doxycycline inhibits bacterial protein synthesis, stopping bacterial growth. It also has some anti-inflammatory properties useful in chronic conditions.
Available formulations
50 mg capsule
100 mg capsule
Oral suspension
Side effects to know
Common side effects
- • Vomiting
- • Decreased appetite
- • Diarrhea
- • Esophageal irritation (give with food and water)
These usually resolve on their own. If they persist past the first few doses, ask your vet.
Call your vet immediately if you see
- ⚠ Severe vomiting or anorexia
- ⚠ Esophageal ulceration
- ⚠ Yellowing of teeth in young puppies (avoid in dogs under 6 months)
Drug interactions
- • Antacids reduce absorption
- • Penicillin-class antibiotics (interaction)
- • Iron supplements
When not to use
- • Pregnant dogs
- • Puppies under 6 months (tooth discoloration)
- • Documented allergy
Monitoring during treatment
Give with food and a full water bowl available — doxycycline can cause esophageal ulcers if it sticks in the throat dry.
Need a Doxycycline refill?
RexVet is the first 501(c)(3) non-profit online vet service in the U.S. Talk to a licensed veterinarian by video, get your dogs's Doxycycline prescription, and have it shipped through RexVetRx — all for $64.99 per visit.
Book a vet visit — $64.99Doxycycline for Dogs
Frequently asked questions
How long does doxycycline treatment last for tick-borne disease?
Standard treatment is 21-28 days for most tick-borne diseases. Some chronic cases may need longer courses.
Why give doxycycline with food?
It causes nausea on an empty stomach and can irritate the esophagus if it sticks dry. Give with food and follow with water to wash it down.
Can RexVet prescribe doxycycline?
Yes — for confirmed or strongly suspected tick-borne illness, respiratory infections, or other clear indications, RexVet can prescribe and ship doxycycline through RexVetRx.
Can I give my dog human doxycycline?
Same active ingredient, but only at vet-determined doses. The capsule form often works for dogs; check with your vet first.
What if my dog vomits up the doxycycline?
Try giving with a more substantial meal next time. If vomiting persists, contact your vet — sometimes switching to doxycycline monohydrate (gentler) helps.
Medical review by Dr. Tiffany Delacruz, DVM
Chief Executive Officer & Lead Veterinarian, RexVet. Licensed in Florida, New York, and Virginia.
Last fact-checked: 2026-05-19
Sources
This page is an educational reference and does not replace veterinary advice. Always consult a licensed veterinarian before starting, changing, or stopping medication for your pet.