Effective Hormonal Treatments to Curb Chronic Egg Laying in Parrots (In-Depth Review)

Chronic egg laying is a common reproductive problem in pet parrots where a hen lays repeated or oversized clutches of eggs without normal rest. This can lead to serious health issues such as calcium depletion (hypocalcaemia), egg binding, yolk peritonitis, osteoporosis, reproductive tract infections and other. While environmental and behavioural modifications are first-line strategies to curb excessive laying, veterinarians also employ pharmaceutical hormonal therapies to temporarily halt egg production when the situation requires it. This article provides a comprehensive comparison of hormonal treatments used in the UK, US, and Europe for managing chronic egg laying in psittacine birds, focusing on drug therapies (behavioural and surgical interventions are not within the scope of this article).

GnRH Agonists (Gonadotropin-Releasing Hormone Analogues)

GnRH agonists are the preferred medical treatment for chronic egg laying in birds due to their efficacy and safety. These drugs are synthetic analogues of GnRH that initially stimulate release of luteinizing hormone (LH) and follicle-stimulating hormone (FSH), but ultimately cause downregulation of pituitary GnRH receptors and suppress gonadal steroid production via negative feedback. In effect, they induce a temporary “off switch” for the bird’s reproductive axis, reducing ovulation and egg laying. Two GnRH agonists are commonly used in avian practice:

• Leuprolide Acetate (Lupron®) – injectable depot formulation

• Deslorelin Acetate (Suprelorin®) – slow-release subcutaneous implant

Leuprolide Acetate (GnRH agonist injection)

Lupron Depot® Injection

Class: Synthetic GnRH super-agonist.

Mechanism: Binds GnRH receptors, causing an initial surge of LH/FSH release followed by pituitary receptor downregulation and suppressed gonadal hormone secretion.

In laymen terms: This drug attaches to certain “hormone switches” in the brain (GnRH receptors). At first, it flips them on, making the body release a burst of hormones (LH/FSH) that tell the ovaries to be more active. But after a short time, the brain stops responding to the drug’s signals, and those switches essentially turn off. As a result, the ovaries stop making their normal reproductive hormones.

Common Brand Names: Lupron Depot® (human formulation) no avian-specific brand.

Dosage Forms & Administration: Injected intramuscularly. Typically given as a long-acting depot injection every 2–3 weeks in birds, with dosing ranging roughly 100–800 µg/kg IM (vary by species). In practice, ~3 injections spaced 2 weeks apart (e.g. 150–800 µg/kg IM q14 days) are often sufficient to halt laying, though some cases require ongoing injections if laying recurs.

Short-term Efficacy: Leuprolide reliably delays or stops ovulation within days, hens usually cease laying for about 2–4 weeks after an injection. However, efficacy can be variable – for example, Amazon parrots showed reduced sex hormones for <3 weeks after a high dose (800 µg/kg).

Long-term Efficacy: Because the effect is temporary, repeated injections are needed for sustained suppression. Many birds resume laying in ~3–4 weeks if not re-dosed. Owners must plan for serial injections during the breeding season. Over the long term, anecdotal reports suggest that birds may become less responsive to leuprolide after many cycles of use, possibly due to antibody formation or hormonal compensation, although controlled studies are lacking.

Side Effects: Leuprolide is considered very safe in birds, with minimal adverse effects observed. Unlike older hormone therapies, it usually does not cause significant systemic side effects. Rarely, injection-site reactions or transient hormone “flare” effects can occur. One report documented suspected anaphylactic reactions in two elf owls after leuprolide injection (an extremely rare complication). Overall, no significant long-term adverse effects have been reported in psittacines.

Deslorelin Acetate (GnRH agonist implant) 

 Suprelorin® implant by Virbac

Class: Synthetic GnRH super-agonist.

Mechanism: Same as leuprolide – persistent GnRH receptor stimulation leading to pituitary desensitisation and suppressed gonadal steroid output.

Common Brand Names: Suprelorin® implant. Suprelorin is labeled for chemical castration in dogs and for adrenal disease in ferrets, but it is also used in pet birds to control egg laying.

Dosage Forms & Administration: A long-acting subcutaneous implant, available in 4.7 mg and 9.4 mg sizes. The implant (a small cylindrical implant similar to a microchip) is placed under the skin by a veterinarian, often in the back between the scapulae (shoulders) or in the inguinal fold (behind the knee) for smaller birds. Placement typically requires sedation, especially in small psittacines. The implant releases deslorelin slowly over time.

Short-term Efficacy: Deslorelin implants take effect within days. A transient rise in sex hormones “flare” may occur initially, but clinical signs of laying diminish as hormone levels fall. The duration of effect varies by species and individual. In general, a 4.7 mg implant can suppress egg laying for an average of 3–6 months in pet parrots. (Studies in other birds demonstrate the range of efficacy: hens ceased laying for a mean of ~6 months in chickens with a 4.7 mg implant, and up to 319 days with a 9.4 mg implant. Pigeons showed ~5–7 weeks of no laying per 4.7 mg implant. In clinical psittacine practice, 3–6 months of anovulation is typical, though some cases may respond for longer or shorter periods.)

Long-term Efficacy: Deslorelin can be re-implanted as needed when laying resumes. Many veterinarians report that consecutive implants (over, say, 6–12 months) can effectively break the chronic laying cycle when combined with environmental changes.

Side Effects: Deslorelin implants are generally very well tolerated and safe. The most common side effect is treatment failure (i.e. lack of effect in a given individual). Mild swelling or irritation at the implant site can occur transiently. Serious adverse reactions are significantly rare. Allergic reactions (e.g. facial swelling, difficulty breathing) are possible but are extremly rare. Overall, deslorelin’s long-term safety profile is good and because it suppresses sex hormones, it may reduce hormonally driven behaviours (which is usually desirable) without the systemic side effects seen with steroid hormones.

Here is a link to an interesting academic paper on "Evaluation of the effects of a 4.7-mg deslorelin acetate implant on egg laying in cockatiels"

Comparison of GnRH Agonists: Both leuprolide and deslorelin act on the GnRH/LH axis to suppress ovulation, and both are effective short-term therapies that can give a laying bird’s body a much-needed rest. The key differences are practical: leuprolide requires frequent injections (every few weeks) and can become costly or stressful with repeated handling, whereas a single deslorelin implant can provide a few months of relief with one procedure. Both treatments are temporary and may need repeating, as neither permanently alters the bird’s reproductive ability. Notably, these hormonal treatments do not address underlying triggers of laying, they reduce hormonal drive but do not modify behaviour or environment. Thus, vets typically use GnRH agonists in conjunction with environmental/behavioural interventions to achieve long-term resolution of chronic egg laying.

Synthetic Progestins (Progesterone Analogues) - Severe Side Effects

Synthetic progestins were historically used to curb egg laying in birds by mimicking the hormone progesterone, which in a laying hen’s body signals the presence of an egg and can suppress further ovulation. By providing exogenous progestin, the goal is to fool the reproductive system into “shutting off” egg production via negative feedback on the hypothalamus-pituitary-gonadal axis (brain).

However, due to serious side effects, these drugs have largely fallen out of favour in avian medicine. Modern avian veterinarians consider progestins a last resort or obsolete option, replaced by safer GnRH agonists.

Key progestin treatments include:

Medroxyprogesterone acetate – long-acting injectable progestin (historically used as “Depo-Provera” injections).

Depo-Provera® by Pfizer

Side Effects: Severe side effects are common, especially with repeated use. Medroxyprogesterone can cause polyuria/polydipsia (excess drinking and urination), voracious appetite, weight gain and obesity, and lethargy. More gravely, it predisposes birds to hepatic lipidosis (fatty liver degeneration), diabetes mellitus, and even cirrhosis and liver failure with chronic use. There is a prominent risk of permanent infertility or reproductive tract pathology. In some cases, sudden deaths were attributed to MPA-induced organ failure. Because of these risks, medroxyprogesterone is no longer recommended for routine management of chronic egg laying. Avian specialists caution that if it is used at all, it should be only infrequently or as a one-time emergency measure, not a continuous therapy.

Megestrol acetate – oral progestin (historically used in small birds; e.g. Ovarid® tablets in UK).

Ovarid® by Virbac

Side Effects: Similar to medroxyprogesterone. Megestrol’s known side effects include polyphagia, weight gain, adrenal suppression, and diabetes. In birds, practitioners observed obesity, hepatic issues, and immune suppression. Notably, megestrol has been linked to impaired immune function and fungal infections in birds at higher doses, and can induce broodiness or cystic changes in the oviduct. One report from pigeon control noted that ovarian regression occurs on megestrol but with risk of rebound hyperactivity once stopped. Because of these hazards, megestrol too is generally discouraged in psittacines.

Note: In older literature, other oestrogen-progestin combinations (like human birth control pills containing norethindrone and mestranol) were tried in pet birds. These had unreliable outcomes and significant risks (e.g. a report of severe hypertension in a duck given an oral contraceptive pill). This underscores why synthetic hormone therapies have largely been abandoned in favour of GnRH analogues. The only scenario where a progestin might be considered today is if GnRH treatments are unavailable and the bird’s life is at risk from continuous laying, and even then with extreme caution.

Androgen (Male Hormone) Therapies - Also Undesirable

Another hormonal strategy used in the past for chronic egg laying was administering androgens (male sex hormones) to female birds. The rationale was that high levels of androgens would interrupt the female ovulatory cycle via negative feedback and perhaps induce male-like behaviours incompatible with egg laying.

Two androgenic compounds have been documented in avian use:

Testosterone (and its derivatives) – e.g. testosterone cypionate injections.

Mibolerone – a potent androgen (formerly marketed as Cheque Drops® for preventing oestrus in female dogs).

Androgen therapy can cause masculinization of female birds (e.g. increased aggression, singing in females of singing species, or male-typical plumage changes in some cases). It is also hepatotoxic: birds, like other animals, can suffer liver damage from excess androgens. Testosterone is contraindicated in any bird with liver impairment. Other adverse effects include weight gain and fluid retention. In one report, chronic androgen administration led to oviductal enlargement and pathology in a hen (thought to be due to anabolic effects on the reproductive tract). These risks, plus the availability of safer alternatives, make testosterone a rarely used and highly undesirable option now.

Comparing Hormonal Treatments

Here is a summary table of all hormonal therapies used in avian species.

Therapy	Class & Mechanism	Notable Side Effects
Leuprolide acetate  (Lupron®)	GnRH agonist (synthetic) – downregulates pituitary LH/FSH, shutting off ovarian stimulation.	Very safe, minimal side effects. Rarely, injection site reaction or allergic response. Does not cause obesity or organ damage.
Deslorelin acetate (Suprelorin® implant)	GnRH agonist (superagonist) – continuous GnRH stimulation leading to pituitary shutdown and gonadal quiescence.	Generally well-tolerated and very safe. Possible mild swelling at implant site. Rare allergic reaction. No systemic side effects like those of steroid hormones.
Medroxyprogesterone (Depo-Provera®)	Progestin (synthetic progesterone) – negative feedback on GnRH; mimics high progesterone of incubation, turning off ovary temporarily.	High risk of serious side effects: polyuria, polydipsia, hyperphagia, obesity, lethargy, hepatic lipidosis (fatty liver), diabetes mellitus, liver failure, and even death with chronic use.
Megestrol acetate (Ovaban®/Ovarid®)	Progestin – same mechanism as above (prolonged progesterone signal to suppress ovulation).	Similar to medroxyprogesterone: weight gain, fatty liver, diabetes, immunosuppression. Long-term use causes adrenal suppression. Cases of repro tract pathology (cystic oviduct) reported. Overall unsafe for chronic use.
hCG (chorionic gonadotropin)  (Chorulon®, Pregnyl®)	Gonadotropin hormone (LH analogue) – triggers ovulation/luteinisation of ovarian follicles, which can disrupt the laying cycle and induce a temporary refractory period.	Few immediate side effects. Generally well tolerated. Repeated use can lead to antibody formation, rendering it ineffective over time. Injection site irritation possible. Overall safer than steroid hormones.
Testosterone	Androgen (male sex hormone) – negative feedback on female HPG axis, induces male secondary traits that conflict with laying behaviour.	Many side effects: aggression, hepatotoxicity (can damage liver, especially methylated or high doses). Contraindicated in birds with any liver issues. Can enlarge the oviduct pathologically. Overall health impact can be negative with prolonged use.
Tamoxifen  (Nolvadex®)	SERM (Selective oestrogen Receptor Modulator) – blocks oestrogen receptors, reducing oestrogen-driven reproductive signals.	Significant risk: caused leukopenia (dangerously low white cell count) in study birds, indicating immune suppression. Potential liver strain. Not proven safe for birds.

Making Informed Choices

Understanding the full range of hormonal therapy options and their potential side effects is essential before deciding with which one to proceed. When selected with care and administered correctly, hormonal therapy can be not only highly effective but also life-saving. Unfortunately, inappropriate or outdated methods are still occasionally used in avian medicine, which can place a bird’s health at serious risk.

Every case should begin with a thorough evaluation of the bird’s overall health status, medical history, environment, and behavioural patterns. These factors are key to determining whether hormonal intervention is truly necessary, as well as to selecting the safest and most effective approach.

Whether you are a veterinarian or a dedicated bird owner, it is important to consider the complete picture and remain informed about current best practices. Avian medicine is a rapidly evolving field, and ongoing research is continually introducing newer, more effective, and less risky hormonal treatments. Staying up to date ensures that decisions are made in the bird’s best interest, maximising benefits while minimising potential harm.

Amazon Parrots Pair

References

1. Abou-Zahr, T. (2022). Avian reproductive disorders. Companion Animal, 27(2), 31–38. https://doi.org/10.12968/coan.2021.0056

2. Bowles, H. L. (2002). Reproductive diseases of pet bird species. Veterinary Clinics of North America: Exotic Animal Practice, 5(3), 489–506. https://doi.org/10.1016/S1094-9194(02)00008-7

3. Carpenter, J. W. (2018). Exotic animal formulary (5th ed.). Elsevier.

4. Cowan, M. L., Martin, G. B., Monks, D. J., et al. (2014). Inhibition of the reproductive system by deslorelin in male and female pigeons (Columba livia). Journal of Avian Medicine and Surgery, 28(2), 102–108. https://doi.org/10.1647/2013-027

5. Food and Drug Administration (FDA). (2012). Suprelorin F (deslorelin acetate) implant – Index listing (MIF 900-013) for ferrets. FDA Center for Veterinary Medicine. (Freedom of Information Summary)

6. Hoppes, S. M. (2021). Reproductive diseases of pet birds. In Merck Veterinary Manual. Merck & Co. (Online edition; revised 2021)

7. Joyner, K. L. (1994). Theriogenology. In B. W. Ritchie, G. J. Harrison, & L. R. Harrison (Eds.), Avian medicine: Principles and application (pp. 748–773). Wingers Publishing.

8. Kennedy, E. D. (1991). Determinate and indeterminate egg-laying patterns: A review. The Condor, 93(1), 106–124. https://doi.org/10.2307/1368612

9. Klaphake, E. A., Fecteau, K. A., DeWit, M., et al. (2009). Effects of leuprolide acetate on selected blood and fecal sex hormones in Hispaniolan Amazon parrots (Amazona ventralis). Journal of Avian Medicine and Surgery, 23(4), 253–262. https://doi.org/10.1647/2008-061R.1

10. Lierz, M., Petritz, O. A., & Samour, J. (2016). Reproduction. In B. L. Speer (Ed.), Current therapy in avian medicine and surgery (pp. 433–460). Elsevier.

11. Mans, C., & Pilny, A. (2014). Use of GnRH agonists for medical management of reproductive disorders in birds. Veterinary Clinics of North America: Exotic Animal Practice, 17(1), 23–33. https://doi.org/10.1016/j.cvex.2013.10.001

12. Millam, J. R., & Finney, H. L. (1994). Leuprolide acetate can reversibly prevent egg laying in cockatiels (Nymphicus hollandicus). Zoo Biology, 13(2), 149–155. https://doi.org/10.1002/zoo.1430130209

13. Petritz, O. A., Sanchez-Migallón Guzmán, D., Paul-Murphy, J., et al. (2013). Evaluation of the efficacy and safety of single administration of 4.7-mg deslorelin acetate implants on egg production and plasma sex hormones in Japanese quail (Coturnix coturnix japonica). American Journal of Veterinary Research, 74(2), 316–323. https://doi.org/10.2460/ajvr.74.2.316

14. Petritz, O. A., Sanchez-Migallón Guzmán, D., Hawkins, M. G., et al. (2015). Comparison of two 4.7-mg to one 9.4-mg deslorelin acetate implant on egg production and plasma progesterone in Japanese quail (Coturnix coturnix japonica). Journal of Zoo and Wildlife Medicine, 46(4), 789–797. https://doi.org/10.1638/2014-0210.1

15. Plumb, D. C. (2023). Plumb’s veterinary drug handbook (10th ed.). Wiley-Blackwell.

16. Rosen, L. B. (2012). Avian reproductive disorders. Journal of Exotic Pet Medicine, 21(2), 124–131. https://doi.org/10.1053/j.jepm.2012.02.013

17. Stringer, E. M., DeVoe, R. S., & Loomis, M. R. (2011). Suspected anaphylaxis to leuprolide acetate depot in two elf owls (Micrathene whitneyi). Journal of Zoo and Wildlife Medicine, 42(1), 166–168. https://doi.org/10.1638/2010-0145.1

18. Summa, N. M., Sanchez-Migallón Guzmán, D., Wills-Plotz, E. L., et al. (2017). Evaluation of the effects of a 4.7-mg deslorelin acetate implant on egg laying in cockatiels (Nymphicus hollandicus). American Journal of Veterinary Research, 78(6), 745–751. https://doi.org/10.2460/ajvr.78.6.745

19. Van Sant, F., & Sundaram, A. (2013). Retrospective study of deslorelin acetate implants in clinical practice. In Proceedings of the 34th Annual Conference of the Association of Avian Veterinarians (Jacksonville, FL, Aug 2013).

20. Veterinary Medicines Directorate (VMD). (2007). Suprelorin 9.4 mg Implant for Dogs and Ferrets (Vm 05653/5018) – Product information. Addlestone, UK: VMD. (Date of first authorisation: July 10, 2007)

21. European Medicines Agency (EMA). (2012). Suprelorin (deslorelin) – EPAR summary for the public. London: EMA. (EMEA/V/C/000109, last updated March 2012)