Egg binding, or dystocia, is a common problem seen in reproductively active hens of all species, although budgerigars (Melopsittacus undulatus), cockatiels (Nymphicus hollandicus) and backyard poultry (Gallus gallus domesticus), are the most commonly presented birds for this problem. The presence of an egg in the coelom has a space occupying mass effect, affecting the bird’s cardiorespiratory function and can result in death from hypoxia and decreased venous return.
Egg binding should be considered a ‘true’ emergency and clients should be encouraged to present their birds early, rather than waiting till the bird is exhausted and compromised.
Predisposing factors include:
• age (very young and very old birds are more frequently affected)
• malnutrition and obesity (it is particularly seen in overweight birds on all-seed diets)
• excessive egg production, especially in cockatiels, budgerigars and backyard poultry, leading to secondary uterine inertia
• lack of physical fitness in caged birds – they seem to lack the physical strength and endurance needed to expel an egg from the body
• oviductal muscle dysfunction, associated with:
o calcium deficiency
o myositis due to excessive egg production
o concurrent salpingitis or metritis
o excessively sized or malformed eggs
• systemic problems:
o concurrent illness
o environmental stress disrupting the egg-laying process
The history of the bird indicates recent or imminent egg laying. Signs of this can include:
• Change in droppings: the faecal component of the droppings becomes larger and softer
• Nesting behaviour: the birds are going in and out of the nest box, chewing the wood around the entrance, and become very defensive of the box – sometimes biting at owners who they were previously closely bonded
• ‘Clucky’ behaviour: the hen holds her body almost horizontal with her wings spread and makes a clucking noise with her beak. This is often triggered by the approach of a ‘mate’ – which may be a person or another bird.
• The presence of recently laid eggs!
Signs of dystocia include:
• Excessive, unproductive straining
• A ‘penguin-like’ posture – the bird stands upright, with its back perpendicular to the ground
• Cloacal prolapse
• The vent (opening into the cloaca) is usually tight. A loose, flaccid appearance to the vent
• opening indicates reproductive activity (Figure 1)
• Coelomic distension (Figure 2)
• Dyspnoea, seen as mouth breathing and exaggerated movement of the sternum and ribs
• Weakness and collapse, often with the wings outspread to help support the bird’s bodyweight. A form of ‘obturator’ paresis may develop, where pressure on the intra-pelvic canal nerves causes paresis or paralysis of the legs. This paresis usually resolves when the pressure is relieved but in some cases the nerve damage may take weeks to repair, if it repairs at all. (Figure 3)
This is based on the history and the clinical signs (see above). Coelomic palpation usually reveals an egg, but soft-shelled eggs can be difficult to detect in this way. Be careful not to push too hard, as this may cause bruising on the dorsal coelomic wall and worsen the bird’s dyspnoea.
Imaging may be required. Radiography is often diagnostic, so long as the egg has a shell (Figure 4). If the bird is stable, a short gaseous anaesthetic and two standard avian orthogonal views will give you much needed information. On the other hand, if the bird is badly compromised, you may need to do a ‘bird in a box’ technique – place the bird in an appropriately-sized cardboard box and take either a DV view or a horizontal lateral view. The positioning will not be good, but the presence of an egg is diagnostic (Figure 5).
If radiology is not available, or if an egg is not obvious on the radiograph, ultrasonography may be required. Use a ventral approach, applying the transducer to an apterylae (featherless tract of skin). Take care to avoid holding the bird on its back, as this throws the weight of the egg and the bird’s viscera onto the air sacs, compromising their respiration. Do not use alcohol on the skin, as this will lower the bird’s body temperature (evaporative cooling) and some alcohol will be absorbed, affecting the bird’s stability. Ultrasound gel is more effective and can be wiped off easily.
Care must be taken to distinguish between egg binding – the acute onset of dystocia – and egg retention, where the egg has been retained for a considerable length of time. If the egg is still in the oviduct, continual deposition of calcium will result in a much thickened and malformed egg shell (Figure 6).
Other differentials include:
• An ectopic egg – one that has either been retropulsed out of the oviduct or, more likely, the oviduct has ‘split’ while the bird was straining. This is difficult to diagnose; the bird does not strain to lay and fails to lay the egg despite treatment. The diagnosis is confirmed by exploratory surgery
• A pyometra: an ultrasound is the best way to diagnose this, remembering that pus in birds in caseous, not liquid, and in the oviduct it often has a lamellated appearance (similar to an onion)
• A cloacolith – a dried concretion of faecal material and urates in the cloaca, often adhering to the cloacal mucosa. The bird strains almost constantly and may pass fresh blood and flatulence when straining. Diagnosis is confirmed by examining the cloaca with an endoscope or otoscope.
If the bird shows no or only mild signs of discomfort and distress, confirm the time the last egg was laid; eggs are usually laid 23–26 hours apart and the patient may not be ready to lay. Sun conures (Aratinga solstitialis) are particularly troublesome in this regard, and the author has seen some individuals take 36-48 hours to lay an egg!
These birds should be:
• Placed in a heated hospital cage with adequate humidity. If a hospital cage is not available, place a heat lamp (e.g. a reptile heat lamp available from pet shops) in front of the cage, ensuring a wide bowl of water is close to the heat source (a wide bowl increases the evaporative surface of the water).
• Given calcium gluconate (5-10mg/kg) by intramuscular injection into the pectoral muscles every 3–6 hours. The calcium gluconate should only be diluted for very small patients (<40g)
• Tube fed a highly digestible, high-sugar supplements (e.g. Poly Aid; Vetafarm, or even sugared water – 1 teaspoon of sugar /100mls water) may be given to provide a rapid source of energy. Stress and handling should be minimised, and the bird should be kept in a dark, quiet environment. Avoid sedation, as the bird will require active muscular contraction to lay its egg.
If the bird fails to respond to this treatment after 12-24 hours (and is not deteriorating), oxytocin (3-5IU/kg IM) may be given but there is controversy over its efficacy in birds – it is not an avian hormone. (Birds utilise arginine vasotocin, but this is not commercially available.) The topical intra-cloacal administration of 0.02-0.1mg/Kg prostaglandin E2 (PGE2) gel (Prostin® vagina gel) will usually produce uterovaginal sphincter dilation and straining within 5–10 minutes. (Birds have both PGE2 and PGF2a, but the latter will not relax the uterovaginal sphincter.) PGE2 gel (Prostin, Pfizer) is usually available from pharmacists and can be stored in the refrigerator after opening for up to 6-12 months without losing efficacy. Gloves should be worn while handling it, and pregnant women should avoid contact with the gel completely.
If the egg is not laid after 15 minutes, gentle manipulation through the body wall can often move the egg into the cloaca and delivered. Caution must be taken not to push the egg up against the kidneys and spine while doing this, causing iatrogenic crush trauma. Occasionally the cloaca may partially prolapse while doing this – it usually reduces immediately once the egg is delivered.
If the egg is visible in the cloaca but cannot be delivered, the egg can be collapsed. This technique, known as ovocentesis, involves an 18g gauge needle with a syringe attached introduced into the egg and, while the contents are aspirated, the egg is simultaneously collapsed with digital pressure. The egg shell is usually passed within 48 hours of this procedure. It must be noted that while this procedure may be life-saving; damage to the oviduct usually requires a salpingohysterectomy at a later date.
If the bird is severely distressed or dyspnoeic, this is an emergency situation and ovocentesis (through the body wall) and egg collapse may be necessary. Again, it must be noted that while this procedure may be life-saving, damage to the oviduct usually requires a salpingohysterectomy at a later date.
In some cases it may be necessary to anaesthetise the bird (mask induction with isoflurane), intubate it and apply intermittent positive pressure ventilation (IPPV) while the egg is being manipulated through the cloaca or while ovocentesis is performed.
Coeliotomy and caesarean section may be necessary when all conservative treatments fail. Such cases include:
• Eggs that cannot be delivered because of their size or shape
• Retained eggs that have adhered to the uterine wall
• Ectopic eggs can result from the uterine portion of the oviduct tearing while the bird is straining, dropping the egg loose into the coelom.
A ventral midline approach is used, taking care not to incise into the intestines when opening the coelom. Unless the egg is ectopic, the oviduct is opened and the egg is removed. Unless the oviduct is abnormal, in small birds (<200g) it often does not require suturing.
A bird that has been successfully treated for egg binding is still a patient requiring care and good nursing for at least 24 hours.
• Keep the bird warm, and ensure it is eating. If not eating, tube feeding with a hand rearing formula may be required
• Give analgesia
o Meloxicam 1.5mg/kg PO q12h for 3-5 days
o Butorphanol 1mg/kg IM q6-8h for 1-2 days
• Placing a deslorelin implant (Suprelorin®, Virbac) SC in the dorsal interscapular space or by shallow IM injection into the pectoral muscles can help to prevent further ovulation
As with all health problems, review and evaluate potential causes and work with the owner to correct or avoid them. Increasing the amount of exercise given to the bird while improving its diet can often prevent future egg binding.
The earlier the case is presented, the better the prognosis. Simple cases have an excellent prognosis, while cases that have reached the stage where the bird is collapsed, dyspnoeic and unable to use its legs properly have a guarded prognosis.
Dr Bob Doneley BVSc FANZCVS (Avian Medicine) CMAVA
Associate Professor and Specialist in Avian and Exotic Pet Medicine
School of Veterinary Science, The University of Queensland
Dr Bob Doneley graduated from the University of Queensland in 1982. After working for 5 years as an associate in veterinary practices in Bundaberg, Brisbane, the UK, and Toowoomba, he opened the West Toowoomba Vet Surgery in 1988. Bob sold the practice in August 2010 to take up a position at the University of Queensland’s new Veterinary Medical Centre where he is now an Associate Professor and Head of the Avian and Exotic Pet Service.
He obtained his Membership of the Australian College of Veterinary Scientists (Avian Medicine chapter) in 1991 and his Fellowship in 2003, becoming Queensland’s first specialist in avian medicine and only the third in Australia. He has authored 2 textbooks on avian medicine and several chapters in other books, as well as over 20 papers in peer-reviewed journals.
Bob has been extensively involved in his profession. As well as being a member of the Australian Veterinary Association and several avian and exotic pet veterinary associations, he has been awarded the ANZCVS Fellowship Scholarship (2002), the College Prize (2003) and the College Meritorious Service Award (2015). He was on the Board of Examiners of the Australian College of Veterinary Scientists from 2004 till 2010. He is now a Director of the Australian Veterinary Association.
- Avian Medicine and Surgery in Practice: Companion and Aviary Birds, 2nd Edition. Doneley B. CRC Press UK, 2016.
- Molter CM, Court MH, Cole GA, Gagnon DJ, Hazarika S, Paul-Murphy JR. Pharmacokinetics of meloxicam after intravenous, intramuscular, and oral administration of a single dose to Hispaniolan Amazon parrots (Amazona ventralis). American Journal of Veterinary Research 2013; 74(3): 375-80.