By Lauren Forsythe, PharmD, DICVP; Rania Gollakner, BS, DVM, MPH

What is doxycycline?

Doxycycline (brand names: Vibramycin®, Oracea®, Monodox®, Periostat®, Doryx®, Acticlate®) is a tetracycline antibiotic used to treat certain infections in small animals, such as anaplasma (a tick-borne disease), heartworm disease, and periodontal (teeth and gum) disease.

Its use in cats, dogs, small mammals, reptiles, or birds to treat infections is “off label” or “extra label”. Many drugs are commonly prescribed for off-label use in veterinary medicine. In these instances, follow your veterinarian’s directions and cautions very carefully, as their directions may be significantly different from those on the label.

How is doxycycline given?

  • Give doxycycline by mouth in the form of a tablet, capsule, or liquid.
  • If administering liquid forms, be sure to measure the medication carefully.
  • If administering tablets or capsules, follow the pill with at least 6 mL of water or food – never give the pill dry. This is particularly important in cats.
  • To ease stomach upset, give this medication with food, but not with food containing dairy or iron, as calcium and iron can block the medication’s efficacy.

This medication takes effect quickly, in about 1 to 2 hours; however, visible effects may take a few days to be recognized. It is important to give this medication to your pet for the entire time prescribed by your veterinarian, even if it appears that your pet is feeling better.

What if I miss giving my pet the medication?

If you miss a dose, give it when you remember. However, if it is close to the time for the next dose, skip the dose you missed, give it at the next scheduled time, and return to the regular dosing schedule. Never give your pet two doses at once or give extra doses.

Are there any potential side effects?

The most common side effects include:

  • vomiting, diarrhea, and lack of appetite (may be lessened by giving the medication with food)
  • increased liver enzymes on bloodwork (more common in dogs than cats)
  • increased skin sensitivity to sunlight and sunburn (especially hairless areas like the nose, eyelids, and ears)
  • ulceration and scarring of the esophagus if the pill gets stuck, leading to difficulty swallowing (dry pilling is not recommended)

More serious side effects include:

  • liver failure, characterized by a yellowing of the skin
  • seizures
  • bleeding
  • behavior changes
  • trouble swallowing
  • upset stomach not directly associated with administration  

Contact your veterinarian if any of these serious side effects occur. This short-acting medication should stop working within 24 hours, although effects can be longer in pets with liver or kidney disease.

Are there any risk factors for this medication?

Doxycycline SHOULD NOT be used in pets that:

  • are allergic to it
  • are in the first half of pregnancy
  • are nursing (because it is excreted in milk)

Doxycycline should be used with significant caution in pets that are in the last half of pregnancy.

Doxycycline should be used with caution in pets that:

  • have significant liver disease
  • are young and still developing bones and teeth   

Are there any drug interactions I should be aware of?

The following medications should be used with caution when given with doxycycline:

  • oral antacids
  • avermectins
  • bismuth subsalicylate
  • kaolin
  • pectin
  • enrofloxacin
  • oral iron
  • penicillins
  • phenobarbital
  • sucralfate
  • warfarin

Be sure to tell your veterinarian about any medications (including vitamins, supplements, or herbal therapies) that your pet is taking.

Is there any monitoring that needs to be done with this medication?

  • There is no specific monitoring that needs to be done while your pet is taking this medication.
  • Monitor for serious side effects and alert your veterinarian if these are noted.
  • Your veterinarian may monitor your pet to be sure that the medication is working.
  • Your veterinarian may schedule a follow-up visit after the course of medication is complete to ensure the infection has been cleared and/or do additional testing to ensure this is the right medication for the type of infection present. In this case, follow your veterinarian’s directions.

How do I store doxycycline?

  • Store away from light.
  • Store tablets or capsules in a tightly sealed container at room temperature (15°C–30°C or 59°F-86°F).
  • Store liquid suspension at room temperature and discard after 14 days or as directed by your veterinarian.
  • Keep medication out of reach of children and pets.

What should I do in case of emergency?

If you suspect an overdose or an adverse reaction to the medication, call your veterinary office immediately. If they are not available, follow their directions in contacting an emergency facility.

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