Estriol

By Krista Williams, BSc, DVM, CCRP

What is estriol?

Estriol (brand name Incurin®) is a natural estrogen used to treat urinary incontinence and other diseases responsive to estrogen.

Its use in dogs to treat anything other than urinary incontinence is considered “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 carefully, as their directions may be significantly different from those on the label.

How is estriol given?

Estriol is given by mouth in the form of a tablet or a compounded capsule, liquid tablet, or chewable tablet.

  • It may be given with or without food. However, if your pet vomits when given this medication on an empty stomach, give future doses with food or a treat.  
  • Measure liquid forms carefully. 
  • Pregnant women should NOT handle this medication; if it is necessary, wear gloves and wash hands immediately after administering.
  • Once this medication has taken effect, your veterinarian will recommend a gradual decrease in dose to find the lowest effective dose.
  • Wash hands after administration.

This medication should take effect within one to two days, and improvements in clinical signs should follow.

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?

Side effects are uncommon if the drug is used at the appropriate lowest effective dose, but may include:

  • reduced or lack of appetite (anorexia)
  • vomiting
  • increased drinking
  • swollen vulva
  • anxiety
  • decreased energy
  • hair loss
  • drooling

Rarely, SERIOUS ADVERSE REACTIONS associated with this drug may occur without warning, including:

  • bone marrow suppression, which may present as lethargy, and/or abnormal bleeding, bruising or fever
  • seizures
  • mammary tumors

This moderate-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?

Estriol should NOT BE USED in pets:

  • that are allergic to it
  • that are pregnant
  • that are receiving other estrogen-based medications
  • that are drinking and urinating large amounts

Estriol should be USED WITH CAUTION in:

  • dogs receiving glucocorticoid therapy
  • dogs with liver disease
  • nursing dogs
  • intact female dogs
  • male dogs
  • dogs less than one year old
  • dogs with bone marrow depression
  • dogs with mammary tumors

Are there any drug interactions I should be aware of?

Although drug interactions have not been noted with estriol at this time, it is recommended to avoid using it at the same time as medications that may suppress bone marrow.

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

Is any monitoring needed with this medication?

  • Before starting estriol, your veterinarian should perform baseline bloodwork and urinalysis. 
  • For long-term estriol use, your veterinarian should perform a complete blood count two to four weeks after starting the medication, and then every three to six months during therapy. 
  • Your veterinarian may recommend recheck examinations to ensure the medication is working adequately and that no contraindications have developed.

At home, monitor for any side effects, such as those noted above; discontinue the medication and contact your veterinarian if these occur.

How do I store estriol?

Store commercially produced tablets at or below 25°C (77°F) in a tight container away from animals and children. For compounded medications, follow the storage directions on the label.

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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