Egg Binding and Chronic Egg Laying
Dr. Jenni Bass
Several factors can cause a bird to lay excessively. These include: Genetics (cockatiels, budgies, lovebirds)
Photoperiod (light-dark cycle)
Constant availability of food and water
Inappropriate stimulation by a perceived mate (usually the owner)
Absence of a natural flock structure
The causes of egg binding include:
Low blood calcium
Dysfunction of the muscles of the reproductive tract
Excessive egg production
Large misshapen or soft shelled eggs
Age, obesity, lack of exercise
Oviduct tumor or infection
Hypothermia and hyperthermia
Dystocia. Dystocia results from the prevention of laying, due to a physical obstruction. This is evident when there has been earlier damage to the cloaca and in cases where an abdominal or cloacal mass is present. It is also seen in first time layers or birds bred out of season.
Consequences of Chronic Egg Laying and Egg Binding
Relatively minor concerns, such as regurgitation, can be associated with egg laying. In the long term, there is loss of weight, feather loss, dehydration, osteoporosis, malnutrition, general debilitation and an increased risk of egg binding or dystocia. Hormonal changes in some species are more dramatic, with potentially serious behavioural manifestations, such as aggression.
If a bird is physically able to lay her egg, she will. Failure of the egg to move normally through the reproductive tract can lead to infection or obstruction of the oviduct. The oviduct can rupture. If unable to expel the egg, the hen can progress very quickly from a state of weakness, anorexia and depression to one of profound shock, septicemia (blood poisoning) and death. A bird who experiences difficulty in laying on one occasion is more likely to experience subsequent problems. The possible consequences of egg binding are related to the factors, which made the bird unable to lay successfully, as well as to the injuries suffered as a direct result of the condition. Paralysis, seizures, broken bones, peritonitis, persistent infections, gradual weight loss, internal adhesions between organs, reduced fertility, chronic illness and death are among the consequences of reproductive tract disease, such as egg binding.
When to Call Your Veterinarian
If your bird has not previously laid, if you have not already addressed the subject with your veterinarian, if the bird has any difficulty laying or if the eggs are abnormal, contact your avian veterinarian.
Examine eggs as they are laid. Abnormal eggs can be a sign of a calcium imbalance or an infection. Calcium is required for normal bone strength, for formation of the egg shell and for normal development of the chick. It is also required for the function of all muscles, including the heart and the oviduct, and if she has a calcium deficiency, the bird may be unable to expel the egg.
If your bird appears weak, if she is on the cage floor, is straining, panting, has a wide based stance, has a swollen abdomen or has trouble breathing, contact your veterinarian immediately. This is an EMERGENCY. The mass of the egg puts pressure on the large vessels of the body, cutting of the return of blood to the heart, and this can rapidly lead to shock and death. Pressure from the egg can also lead to paralysis, kidney damage and toxicity secondary to retention of droppings. Excessive straining can result in oviduct damage or rupture, as well as prolapse of the oviduct or cloaca.
Treatment of Egg Bound Birds
Birds who are laying abnormal eggs should have a physical examination, as these hens are more likely to experience difficulty when they lay. Diet should be reviewed and tests to detect possible underlying causes or effects of reproductive problems will likely be recommended. Calcium and vitamin therapy may be recommended.
Treatment of the egg bound bird must be decided on a case by case basis, but is usually based on supportive care unless specific treatments are indicated. The bird should be kept warm, and almost always requires fluid therapy to combat shock. Calcium, antibiotics, corticosteroids and drugs which provide pain relief are often used. If the egg is not laid naturally, it must be removed. Eggs can be removed through manual manipulation, by means of medical therapy or surgically. The choice of technique is made on an individual basis. Once the egg has been removed, many birds need a minimum of 24 hours of intensive care. They need to be monitored closely after this, as many previously egg bound or dystocic hens will lay again soon. Follow up tests or visits are usually recommended.
Preventing The Problem
Ideally, birds are on an optimal plane of nutrition and in good health, so that should they lay, they are able to do so with a minimum of risk. This applies equally to companion birds and to those intended for breeding. Behavioral modification can be successful in discouraging birds from laying.
In the past, several forms of hormone therapy have been used in an attempt to curtail excessive laying or to stop it altogether when it threatens the life of the bird. Some of these drugs have serious side effects, such as weight gain and liver damage. It is inappropriate to use hormone therapy in animals which have not undergone a thorough medical work up. Treatment is not always successful and when it does work, the efficacy often decreases with time and injections are required more frequently until they no longer work. A drug has become available more recently, which shows promise in at least the temporary prevention of laying and does not carry serious side effects, but there really is no easy answer.
Surgical prevention of egg laying involves a salpingectomy or spay (the oviduct, but not the ovary is removed). Candidates for this major surgery must be carefully selected.
It is recommended that every bird have an annual examination, perhaps more often if your pet is a laying hen. The chronic layer or a hen with a history of egg binding will only benefit from sound dietary, environmental, medical and behavioral management.