Incurin

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Medically reviewed

Rosario Oropesa

Last updated on 22/12/2025

This page provides general, reference-level information compiled from official medical sources. It is not a substitute for professional medical advice, diagnosis, or treatment. For decisions about your health, please consult a qualified healthcare professional.

Overview of Incurin

What is Incurin?

Incurin is a veterinary medication specifically formulated for use in female dogs. It is a hormonal therapy used to manage certain types of urinary incontinence, a condition where a dog loses voluntary control over urination.

Active Substance and Mechanism

The active ingredient in Incurin is estriol, a naturally occurring short-acting estrogen. In female dogs, estrogen plays a vital role in maintaining the muscle tone of the urethral sphincter. When estrogen levels are insufficient, this sphincter—the muscle responsible for keeping the bladder closed—may weaken, leading to involuntary urine leakage.

Estriol works by binding to estrogen receptors in the cells of the lower urinary tract. This interaction helps to increase the resting muscle tone of the urethra, improving the animal's ability to retain urine.

Primary Use in Veterinary Medicine

Incurin is primarily used for the treatment of hormone-responsive urinary incontinence. This condition is most commonly observed in spayed female dogs. The surgical removal of the ovaries (ovariectomy or ovariohysterectomy) results in a significant decrease in natural estrogen production, which can lead to the gradual weakening of the urethral closure mechanism over time.

By supplementing estrogen levels with estriol, the medication helps restore the functional integrity of the urinary tract, reducing or eliminating the frequency of accidents. Because estriol is a short-acting hormone, it is typically utilized for long-term management of the condition rather than as a one-time cure.

Regulatory References

  1. U.S. Food and Drug Administration (FDA)

What side effects are possible with Incurin?

Possible Side Effects and Safety Information

The safety profile for Incurin, containing estriol, is documented in official government regulatory sources, detailing potential adverse reactions and special safety constraints. Side effects are often classified based on the organ systems they affect and their documented frequency.


Official Adverse Reactions and System Classifications

Adverse reactions listed in regulatory prescribing information primarily fall into three system-organ classes: gastrointestinal, reproductive, and nervous/behavioral effects.

  • Frequency Classification: Oestrogenic effects (such as swollen vulva and swollen mammary glands) and vomiting are classified with an incidence of approximately 5% to 9% at the highest recommended daily dose, according to the European Summary of Product Characteristics (SmPC). Vaginal bleeding is reported in rare cases.
  • Other Documented Effects: Other reactions include anorexia, lethargy, aggression, polydipsia, and behaviors associated with estrous behavior.

Serious Adverse Reactions and Safety Constraints

Regulatory documents highlight several potentially serious events reported in extended safety studies, including possible stump pyometra, an increase in epileptic seizures, and changes to circulating blood cells, such as anemia, leukopenia, and thrombocytopenia.

Usage is subject to explicit contraindications. The medication is officially constrained from use in intact female dogs, pregnant dogs, and dogs exhibiting polyuria secondary to polydipsia. Furthermore, the safety and effectiveness have not been evaluated in dogs under one year of age or those used for breeding. Adverse effects are often linked to high systemic exposure and are stated to be reversible after lowering the dose.

Overdose and Emergency Response

Overdose and When to Seek Help

Official regulatory documentation structures the overdose profile for estriol (Incurin) around the occurrence of reversible effects and mandated professional action.

Attribute Official Regulatory Information
Documented Overdose Presentations Occurrence of typical oestrogen effects is the primary presentation.
Physiological Systems Affected Primarily affects the urogenital and endocrine systems, manifesting as effects such as swollen vulva and mammary glands.
Emergency-Response Statement Seek professional veterinary attention immediately.
Specific Management Measure Management involves lowering the dose, which regulatory documents state makes the associated effects reversible.

Detailed Official Overdose Statements

  • Overdose is formally described by the development of typical oestrogen effects.
  • Specific clinical manifestations documented include swollen vulva, swollen mammary glands, attractiveness to males, and vomiting.
  • Regulatory labeling requires that a suspected overdose necessitates seeking immediate professional veterinary attention.
  • The procedural step for addressing overdose manifestations is the lowering of the dose, as the official labeling states the effects are reversible following this action.
  • No specific pharmacological antidote is documented as being available or known in the official regulatory prescribing information.

Therapeutic Uses of Incurin

What Incurin Treats: Main Uses and Benefits

Incurin is generally applied in situations where additional symptomatic support is needed for the lower urinary tract, specifically in dogs where bladder control issues have arisen as a consequence of spaying.


Addressing Involuntary Urine Leakage Post-Spay

This domain covers the primary condition and the direct physical symptom: hormone-responsive urinary incontinence. The medication is commonly used in clinical settings where the loss of ovarian hormones following ovariohysterectomy (spaying) affects functional stability. It is commonly used to help with symptoms related to functional stress, such as involuntary urine leakage, and is relevant for easing symptoms related to heightened physiological activity.

The medication is indicated for the control of estrogen-responsive urinary incontinence in female dogs that have been ovariohysterectomized (spayed).


Supporting Long-Term Urinary Stability and Comfort

This classification centers on providing long-term pharmacological support for stabilizing urinary function, and is relevant in contexts involving recurrent or episodic manifestations. This use is specifically for chronic, enduring manifestations, applied across domains where additional symptomatic support is needed. It is often used during phases when symptoms become more noticeable, as opposed to symptoms linked to organ-specific functional stress. This support assists with maintaining functional stability and helps improve day-to-day comfort during symptomatic periods, which is applied in addressing symptoms that interfere with daily functioning.


“It is commonly used to address symptom clusters that may become intense or disruptive, helping to stabilize functional stress.”

Quick Fact: Support for Hormone-Responsive Incontinence
Target Condition Chronic, acquired urinary incontinence in spayed female dogs
Primary Symptom Managed Involuntary urine leakage, especially during rest
Benefit Focus Supports functional stability and helps ease symptom load

Regulatory References

  1. U.S. Food and Drug Administration (FDA) Freedom of Information Summary

Eligibility and Restrictions for Use

Incurin's official eligibility and non-eligibility profile is strictly defined by government regulatory documents, focusing primarily on the animal’s reproductive status and age.

Approved Target Population

Use of Incurin is indicated exclusively for ovariohysterectomized (spayed) female dogs diagnosed with estrogen-responsive urinary incontinence.


Absolute Contraindications

Regulatory authorities list several populations for whom Incurin is explicitly contraindicated and must not be used:

Classification Population Group
Reproductive Status Intact female dogs
Physiological State Pregnant dogs and lactating (nursing) dogs
Age Threshold Dogs younger than 1 year of age

Specific Use Restrictions and Limitations

Use of the medicine is not recommended in dogs that are exhibiting signs of polyuria-polydipsia (excessive thirst and urination). Furthermore, safety and efficacy have not been evaluated in key populations, including:

Restriction Focus Population Group
Comorbidity Dogs with existing liver disease
Sex Male dogs
Breeding Status Dogs used for breeding purposes

Eligibility is limited to spayed females and is prohibited if the animal falls into any of the contraindicated categories or has an unstudied condition like liver disease, according to official regulatory documentation.

What should I know about interactions with other medicines?

Interactions with other medicines and products

The official regulatory profile for estriol identifies specific constraints regarding co-administration and systemic exposure, though the European label generally states that no other specific interactions are known. The principal restriction across all regulatory documents is the explicit prohibition against using this product with other estrogens. This is formally classified as a contraindicated combination due to the risk of additive hormonal effects.

Interaction Category Documented Constraint
Prohibited Co-Administration Must not be used with other estrogens.
Un-Evaluated Co-Use Concomitant use with glucocorticoids has not been evaluated in formal studies.
Exposure Documentation Repeated oral administration may result in elevated estriol systemic exposure.
Food Interaction The effect of the prandial state (food) on bioavailability has not been evaluated.

An additional regulatory caution exists for certain patient populations, as the use of the medicine in dogs with liver disease has not been evaluated in formal studies. This is an important consideration, as altered metabolism in this population could significantly affect the interaction profile. The regulatory data notes the potential for elevated estriol systemic exposure following repeated oral dosing due to the drug's apparent enterohepatic recycling. No mandatory time separation or dosing rules are documented in the official labeling. This combination of explicit prohibition and caution regarding un-evaluated co-administration and populations forms the entire published interaction structure.

Mechanism of Action

Incurin's mechanism is defined by the action of its active ingredient, Estriol, which functions as a weak agonist of estrogen receptors ( ERalpha and ERbeta). It selectively targets tissues in the lower urogenital tract. This molecular interaction initiates the genomic signaling pathway as the receptor-ligand complex translocates to the cell nucleus to modulate gene transcription. This process drives trophic effects, promoting an increase in tissue bulk, collagen content, and vascularity in the urethral mucosa and submucosa. Concurrently, these genomic changes enhance the content and sensitivity of alpha-adrenergic receptors in the urethral smooth muscle. By potentiating existing autonomic signaling, this mechanism augments the smooth muscle's resting tone and contractility. The combined tissue thickening and augmented muscle tone significantly raise the Maximal Urethral Closure Pressure (MUCP), establishing a higher urethral resistance as a system-level physiological consequence.

Dosage and Administration Information

How to Use Incurin: Administration Guidelines

The usage of Incurin is based on a standardized, two-phase protocol designed to identify and maintain the lowest effective daily dose over the long term. Administration is via the oral route using the 1 mg tablet.


Dosing Protocol and Frequency

Feature Administration Guidelines
Starting Dose Administer 2 mg once daily, regardless of body weight, for a minimum of 14 days.
Maintenance Dose The dose is gradually reduced in a step-wise manner (e.g., 2 mg to 1 mg to 0.5 mg) until the lowest effective dose is achieved.
Maximum Dose Administration must not exceed 2 mg per day.
Maintenance Frequency The lowest effective dose is given once daily or, if appropriate, once every two days.

Procedural and Administration Conditions

Administration of Incurin follows a specific procedural structure focused on dose adjustment and timing. The tablets may be administered with or without food, and they can be crushed and mixed into food or a treat to aid ingestion.

A critical component of the usage protocol is the titration schedule: a minimum of 7 days must pass between each dose adjustment. If the initial starting dose is maintained for two weeks and no response is observed at the maximum 2 mg dose, a procedural re-assessment of the diagnosis is indicated. The use has not been evaluated in young animals (less than 1 year of age) or those with liver disease.

Recent Clinical Evidence

Research Evidence / Overview of Studies for Incurin


The Research Landscape for Hormone-Responsive Incontinence

The official research record for Incurin was evaluated in studies examining hormone-responsive urinary incontinence that developed after female dogs underwent spaying (ovariohysterectomy). The research primarily consists of pivotal, multi-center field studies conducted with client-owned dogs under veterinary supervision. The designs of these studies varied. While most utilized an open-label or self-controlled design, at least one trial included a short, initial placebo-controlled phase. These designs were used in research exploring how symptoms change over time when the medication was observed in the study population.


Study Focus: Measuring Continence Status and Urethral Function

The clinical trials monitored and measured outcomes reflecting daily functioning or activity level related to urinary patterns. Researchers examined outcomes related to involuntary urine leakage and had owners and investigators classify the dog's continence status after a period of use, which applied in studies examining patient-reported experiences.

Additionally, some studies explored more technical measurements. These focused on outcomes monitoring physiological strain or stress, specifically using devices to measure urethral pressure parameters, which were evaluated in relation to the study period. Findings describe patterns observed in the studies related to measurements taken of both subjective reports of continence and objective pressure parameters during the study period.


Research Gaps and Unanswered Questions

The research record is clear that Incurin was evaluated in a very specific population: ovariohysterectomized (spayed) female dogs. The results apply only to the populations studied. Research provides context but not individual predictions, and data for certain groups (such as intact female dogs or males) remain insufficient.

Furthermore, comparative evidence is lacking against other active treatments for this condition. While long-term observational data exist, the follow-up durations were limited in highly controlled settings, meaning the durability of patterns in diverse, long-term scenarios is not fully established.

Key Studies & References

  1. U.S. Food and Drug Administration (FDA) Freedom of Information Summary for Incurin (Estriol)
  2. Estriol - DailyMed (National Library of Medicine)
  3. Incurin Tablets (Estriol 1 mg) - Product Information (Merck Animal Health)

Frequently Asked Questions (FAQ)

Common questions about Incurin (FAQ)

Q: How quickly does Incurin start working for its intended use?

Official product information notes that an improvement may be observed within a few days of starting treatment. However, official instructions indicate that at least seven days should be allowed for observation before assessing a dose change, as the full effect may take time to develop.

Q: How long do the effects of Incurin last after it is used?

The active ingredient, estriol, is officially described as a short-acting estrogen with a brief receptor binding time. The product is administered on a once-daily schedule.

Q: What happens if I forget to use Incurin as intended?

Official patient instructions describe the action to take if a dose is missed. If the next scheduled use is imminent, regulatory instructions state the missed dose should be skipped to maintain the schedule. It is specifically stated that two doses should not be given at once.

Q: Are there any common supplements that interact with Incurin?

The official product characteristics note that no other specific interactions are known beyond the constraints explicitly listed in the product label. The main restriction is that the medicine must not be used with other estrogens.

Q: Can Incurin affect how other medicines for chronic conditions work?

Official regulatory documents state that no other specific interactions are known apart from the explicit warning not to use it with other estrogens. Separately, the concomitant use of this medicine with glucocorticoids (a type of steroid) has not been formally evaluated in studies.

Q: Is it normal to feel no change immediately after starting Incurin?

The lack of an immediate change is consistent with the drug’s protocol. Official guidance requires a period of observation, and the initial dose is given for up to two weeks before any adjustment is considered. Effectiveness is often measured after a sustained period of use.

Q: Can Incurin cause changes in appetite?

Official safety documents list anorexia (loss of appetite) as a documented adverse reaction. Other noted reactions that affect consumption include polydipsia (excessive water drinking).

Q: Does Incurin affect blood sugar levels?

Regulatory documents do not directly state that the medicine affects blood sugar levels. However, its use is officially contraindicated in dogs that are already showing polyuria secondary to polydipsia (excessive thirst and urination), which may be symptoms of endocrine diseases.

Q: Do official documents mention Incurin's effects on mental state?

Yes, official documents list some behavioral changes among the documented adverse reactions. These include reports of lethargy, aggression, and behaviors associated with estrous behavior (being attractive to males).

Q: How does Incurin compare to over-the-counter remedies for the same issue?

The official research record notes that comparative evidence is lacking against other active pharmaceutical treatments for this condition. Regulatory sources do not contain information comparing this medicine to over-the-counter remedies.

Q: What information is available about stopping the use of Incurin?

Official documents note that any associated hormonal adverse effects are reversible after lowering the dose. Official patient materials note that treatment is generally continued long-term, and advise against abrupt cessation without specific veterinary guidance.

Q: Why do some people say Incurin takes weeks to show effects?

This timeframe aligns with the official administration protocol. The initial dose is administered for a minimum of 14 days, and the final effective dose is determined through a step-wise reduction process that takes several weeks. This titration schedule is necessary to find the lowest dose that provides a sustained response.

Q: Are allergic reactions to Incurin common?

Official documentation does not specifically list or provide a frequency for generalized allergic reactions. However, some documented adverse reactions, such as vomiting, are classified with an incidence of approximately 5% to 9% at the highest recommended dose.

Q: What research exists about Incurin's effect on bone density?

While some hormones can affect bone, safety studies for this product specifically reported no evidence of bone marrow suppression over a six-month period. A direct effect on bone density, however, is not detailed in the official product information.

Q: Is there a recommended way to switch from a similar medicine to Incurin?

Official regulatory documents explicitly state that the product must not be co-administered with other estrogens. The official labeling does not specify any mandatory time separation or 'washout' period when transitioning from a similar medicine.

Q: What have clinical studies primarily focused on regarding Incurin?

Clinical studies primarily focused on measuring continence status through investigator and owner reports of urinary patterns. They also utilized technical equipment to measure urethral pressure parameters, which indicate the physiological resistance of the urethra.

Q: Has there been any research about Incurin's effects on other body systems?

Yes. Beyond the primary treatment area, research and safety studies documented effects across gastrointestinal, reproductive, and nervous/behavioral systems. Changes to circulating blood cells, such as reports of anemia, have also been noted.

Q: Is Incurin available without a prescription in some places?

Official labeling classifies this as a Prescription Animal Drug. In many regions, including the US, labeling indicates the drug is restricted to use by or on the order of a licensed veterinarian.

Q: What is the official chemical name of the active substance in Incurin?

The active ingredient is Estriol. Its official USP chemical name is the long-form scientific identifier: Estra-1,3,5(10)-triene-3,16,17-triol, (16α,17β)-.

Q: Do I need special monitoring while using Incurin?

Official documentation does not mandate specific routine blood work or monitoring. However, it does advise evaluating all factors contributing to the condition prior to starting administration, and serious events like changes to circulating blood cells have been reported in safety studies.

Q: What is the official classification of Incurin (e.g., estrogen, agonist)?

The medicine is classified as a natural estrogen. Its active ingredient functions as a weak agonist of estrogen receptors, meaning it only partially activates these receptors in the body.

Q: Why is Incurin's mechanism of action described as selective?

The mechanism is considered selective because the active ingredient preferentially targets and has a high affinity for receptors in the cells of the lower urogenital tract. Additionally, it has a short receptor occupancy time, which helps limit the effects on other non-target tissues.

Q: Can using Incurin affect sleep patterns?

Official documents do not specifically list an effect on sleep patterns. However, documented adverse reactions include lethargy and other nervous/behavioral changes, which could potentially impact rest.

Q: Does Incurin have any known contraindications with herbal products?

The official Summary of Product Characteristics states that no other specific interactions are known. The only explicitly prohibited combination is co-administration with other estrogens.

How should Incurin be stored and disposed of?

Storage and Disposal Instructions for Incurin

Official regulatory labeling dictates strict rules for the storage and handling of Incurin (estriol) tablets.


Storage Requirements

Incurin must be stored under controlled conditions and not above 30 C. To maintain product integrity and its 3-year shelf-life, the tablets must be kept in their original container (blister package). For safety, the medication must be stored out of the reach and sight of children.


Disposal Requirements

Unused or expired Incurin tablets must not be disposed of via household waste or wastewater. Disposal must be performed in accordance with local regulations and established collection systems for medicinal products.

Attention! Always consult to a doctor or pharmacist before using pills or medicines.

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