Estriol

What is estriol?

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

Its use in dogs to treat anything other than urinary incontinence is considered off label (extra label). Many drugs are commonly prescribed for off-label use in veterinary medicine. “Off label” means the drug is being used in a way that has not been reviewed or approved by the U.S. Food and Drug Administration (FDA) or Health Canada. 

In these instances, follow your veterinarian’s directions and cautions carefully, as they 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.
• DO NOT handle this medication if you could become pregnant, you are pregnant, or you are breastfeeding. If it is necessary, wear gloves and wash your hands immediately after administering it.
• Once this medication has taken effect, your veterinarian will recommend a gradual decrease in dose to find the lowest effective dose.
• Wash your hands after giving this medication.

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 as soon as you remember, and then continue with the regular dosing schedule. However, if it is almost time for the next dose, skip the missed dose and resume the regular dosing schedule. Do not give the pet two doses at once.

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 appetite or lack of appetite (anorexia)
• Vomiting
• Increased drinking
• Swollen vulva
• Anxiety
• Decreased energy
• Hair loss
• Drooling

Serious adverse reactions may occur. If any of the following signs develop, stop giving estriol and contact your veterinarian immediately:

• Bone marrow suppression, which may present as lethargy 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?

DO NOT USE estriol in:

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

USE 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?

There are no documented drug interactions for this medication; however, 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 before starting any treatment.

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 2 to 4 weeks after starting the medication, and then every three to six months during therapy.
• Your veterinarian will let you know when and how they want to reassess your pet to ensure the medication is working and not causing side effects. 
• At home, monitor for any side effects such as those noted above. If any occur, stop using the medication and contact your veterinarian. 

How do I store estriol?

• Store commercially produced tablets at or below 77°F (25°C) in a tight container.
• Store compounded forms of this medication according to the label.
• Keep the 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. Be prepared to provide information about the product and your pet's weight and symptoms. Report any adverse effects to the FDA or Health Canada.