- Reproductive disease is most commonly seen in small parrot species like the cockatiel, lovebird, and budgerigar parakeet.
- A normal physiologic change in the hen gearing up to lay eggs is ossification of long bones or osteomyelosclerosis which provides a critical calcium reserve for the processes of shelling and passing the egg.
- The initial approach to dystocia should include fluids, warmth, humidity, and in many situations, calcium administration.
- Halt or reduce egg laying in the chronic egg layer with the use of medication such leuprolide acetate and environmental modification techniques.
- Household techniques that can halt or reduce egg laying include removal of reproductive stimuli (i.e. real or perceived mates, nesting material, or mastubatory objects), leaving eggs in the cage as long as possible, and short-term reduction of photoperiod to eight to ten hours of light.
Although any species can be affected, the incidence of reproductive tract is particularly high in small species like the budgerigar parakeet or “budgie” (Melopsittacus undulatus), cockatiel (Nymphicus hollandicus), and lovebird (Agapornis spp.).
Many parrot species are sexually monomorphic and DNA sexing is the most reliable non-invasive technique of gender identification. Laparoscopy or surgical sexing is generally reserved for valuable, breeding birds (Fig 1).
- Feather coloration may be used to distinguish gender in wild-type or standard cockatiels. Males are brighter in color with a bright yellow crest and bright orange cheek patches. Female coloring is much more muted, and she also has horizontal barring on her wing and tail feathers. Visual determination of gender is much more difficult in the many cockatiel color mutations. The eclectus parrot (Eclectus roratus) is the most dramatic example of sexual dimorphism with the female a ruby red color and the male green.
- The cere of the male budgerigar is usually blue and the female is a pinkish-brown.
- Differences in iris color are a subtler example of sexual dimorphism seen in white and pink cockatoos. The male tends to have a black or dark brown iris while the female’s iris is light brown or reddish-brown.
The budgerigar parakeet reaches puberty at 3 to 4 months of age. Cockatiels are generally 6 months of age at the time of puberty. Most medium-sized to large parrots reach puberty sometime between 3 to 6 years.
A reproductive history should be obtained in any female bird:
- When was the last clutch, or collection of eggs, laid?
- How many eggs were laid?
- Were the eggs normal in size and shape?
- Has broody or reproductive behavior been observed such as an increase in appetite, particularly for calcium-rich foods?
- Does the bird seek dark places or exhibit nest-building behavior like paper shredding?
- Some birds may become cage protective or aggressive.
Careful observation of the patient prior to manual restraint can yield valuable clues that increase the index of suspicion regarding reproductive tract disease:
- Cere hypertrophy develops in budgies secondary to high blood estrogen levels. Elevated estrogen levels may be seen in high egg producing hens or in male and female birds with gonadal tumors (Fig 2).
- Hens can produce voluminous droppings secondary to normal physiologic relaxation of the cloaca prior to egg laying.
- Reproductive conditions that involve a large egg or organomegaly can lead to air sac compression and subsequent tachypnea or dyspnea. It is often prudent to postpone physical examination of the dyspneic bird until after cage rest in an oxygen cage.
- Coelomic distension is a common finding in the bird with reproductive disease.
- A shelled egg is easily detected. Carefully and gently palpate the egg to get a general idea of its size, shape, and orientation.
- In rare cases of salpingitis or metritis, cloacal discharge may also be detected.
A normal radiographic finding in the hen gearing up to lay eggs is ossification of long bones or osteomyelosclerosis. Bone marrow ossification occurs secondary to rising estrogen levels and therefore may be a pathologic change (i.e. gonadal tumors) or physiologic change (i.e. normal egg laying). Osteomyelosclerosis provides a critical calcium reserve for birds to shell and pass the egg through the reproductive tract (Fig 3).
Horizontal radiography can be a good option in patients that are not up to the stress of standard survey radiographs. The bird is placed in a bag or box and the x-ray beam is directed horizontally. The patient may be evaluated for crude findings such as egg size, shape, and position, as well as the presence of osteomyelosclerosis.
Egg binding occurs when the egg fails to pass though the oviduct at a normal rate. This rate normally ranges from 24 to 48 hours in most companion parrot species. In egg binding, the egg is not stuck and the bird is not in distress, however, an egg that moves slowly through the reproductive tract may be at increased risk of developing problems.
Fluid therapy and calcium supplementation may promote movement of the egg. Antibiotics may be indicated if metritis or salpingitis are thought to play a role.
In dystocia the egg is stuck in the caudal uterus, vagina, or uterovaginal sphincter. The egg can compress blood vessels causing to cold, pale feet, or even shock. Nerve compression can lead to paresis or paralysis. The egg can also interfere with elimination leading to metabolic problems, and pressure on the oviductal wall can lead to necrosis and rupture.
Diagnosis of dystocia often relies on history, observation of the patient, and careful palpation. During normal egg laying, the bird displays a wide-based stance and a vigorous tail bob caused by abdominal straining. Birds in dystocia often exhibit non-specific signs of illness (depression, lethargy, fluffed and ruffled), tachypnea, and persistent tail bobbing. Blood may be seen from the vent or in the droppings. Evaluate the vent to see if the egg is visible during physical exam. If the bird is sufficiently stable, use survey radiographs to evaluate egg size, shape, and position and evaluate clinical pathology, especially calcium.
|Signs of dystocia in the bird can include:|
Initial efforts should be directed towards stabilizing the patient. Give warmed fluids with or without dextrose, and place the bird in a warm, dark, humidified environment. Calcium is indicated, particularly in birds on an all-seed diet or chronic egg layers.
If the egg does not pass with the use of fluids, humidity, and calcium, stimulate uterine contractions using oxytocin or prostaglandin F2 alpha (Lutalyse®, Pfizer). Neither drug relaxes the uterovaginal sphincter, therefore their use in complicated cases of dystocia with adhesions, oversized egg, or oviductal torsion can lead to reverse peristalsis or even uterine rupture. Gentle abdominal massage can also prove helpful.
Treatment should be most aggressive in small birds such as canaries or finches. Administer oxytocin or Lutalyse® if the egg has not been passed within an hour in these tiny patients. A medium-sized or large parrot can be observed for up to 24 hours as long as the bird is stable.
Drug therapy is generally attempted for 12 to 24 hours unless the bird’s clinical condition requires quicker intervention (i.e. cold, pale feet; not standing, not defecating). More aggressive techniques include:
- Ovocentesis: The percutaneous or cloacal aspiration of egg contents using a large bore needle (i.e. 18-gauge) while manually stabilizing the egg. After removing egg contents, remove the needle and implode the egg using firm, steady, side-to-side digital pressure. If possible, fragments should be extracted with hemostats. Although, shell fragments theoretically can be passed over several days in the well-hydrated patient, this generally does not occur. Nevertheless collapse of the egg relieves pressure and dramatically improves the bird’s clinical condition.
- Manual expression of the egg using gentle digital pressure under general anesthesia. Use caution and do not press cranially when stabilizing the egg as this will compromise respiration.
If medical techniques and drugs prove unsuccessful or if shell fragments must be removed, surgical management (laparotomy and hysterectomy) can be performed after the patient has been stabilized by an experienced avian veterinarian.
After the egg has been laid:
- Administer a drug to inhibit egg laying such as human chorionic gonadotropin (HCG), or more commonly, leuprolide acetate.
- Provide environmental modifications to minimize egg laying behavior.
- Consider antibiotics since assisted egg laying can lead to a flaccid cervix allowing the reflux of feces, urine, or urates into the uterus and secondary salpingitis or metritis.
- Improve nutrition, particularly the calcium and protein content of the diet
- Identify the underlying cause(s) of dystocia. Multiple factors are probably involved in dystocia or egg binding including:
- Chronic egg production
- Large, misshapen or malformed eggs
- Obesity or lack of exercise
- Elderly birds, birds laying their first clutch, and birds bred out of season
- Calcium deficiency, vitamin E/selenium deficiency
- Oviductal disease (infection, neoplasia, or trauma)
- Cloacal masses
- Systemic disease or other stressors
Egg yolk peritonitis
Ectopic ovulation occurs when the infundibulum or proximal, funnel-shaped segment of the uterus fails to engulf an ovum or fails to retain the ovum because of oviductal rupture or reverse peristalsis. Potential causes of ectopic ovulation include oviductal fat, trauma, or oviductal disease. In chickens, ectopic ovulation occurs relatively frequently and in most cases yolk surrounding the ovum is resorbed over 24 to 48 hours without incident. In some instances, however, the presence of yolk within the coelomic cavity is associated with a profound inflammatory reaction or egg yolk peritonitis. Clinical signs of yolk peritonitis can include depression, anorexia, coelomic distension, tachypnea, dyspnea, and sudden death.
To confirm peritonitis, perform abdominocentesis aseptically. Insert the needle on the midline just distal to the sternum, with the needle directed towards the right to avoid the ventriculus. Opaque yellow, green or brown yolk material may be aspirated. Perform cytology and culture/sensitivity to look for bacteria and confirm the presence of yolk globules. Although most cases of yolk peritonitis are sterile, the most common cause of septic peritonitis is E. coli. Other coliforms, Yersinia pseudotuberculosis, Staphylococcus spp., and Salmonella spp. have also been reported. Laboratory results can include a transient increase in blood glucose, elevated triglyceride levels, and marked heterophilic leukocytosis. If needed, celiotomy or endoscopy may be performed by an experienced avian veterinarian to assess associated internal pathology.
Yolk peritonitis requires aggressive supportive care and anti-inflammatory therapy such as meloxicam. Since yolk is a wonderful medium for bacterial growth, the patient should also be started on antibiotics. Occasionally surgical removal of yolk and irrigation of the coelomic cavity is indicated. Again, this procedure is performed by the avian veterinarian, who will take care to prevent fluid from entering the lungs.
Possible sequelae to yolk peritonitis include pancreatitis, transient diabetes mellitus, and yolk emboli.
Cloacal or oviductal prolapse
During normal egg laying or oviposition, the cloacal prolapses but then quickly retracts. Retraction of the cloaca may be slowed or absent in an obese hen or one with hypocalcemia. Excessive abdominal contractions caused by an abnormal egg, dystocia, or cloacal disease can also promote cloacal prolapse (Fig 4 and Fig 5).
Keep all exposed tissues as moist as possible using sterile water-soluble lubricant. Collect culture and sensitivity samples, then clean tissues thoroughly and gently using sterile saline and dilute antiseptic solution. Topical anti-inflammatory agents such as dimethyl sulfoxide (DMSO), oxytocin, prostaglandin F2 alpha, or dextrose can be applied to shrink tissues. Gently replace prolapsed tissue and place two simple interrupted or one horizontal mattress suture to prevent the immediate recurrence of prolapse. After the prolapse has been reduced, place the patient on systemic antibiotics, anti-inflammatories, and possibly a stool softener such as lactulose. Prognosis is good with prompt treatment, although prolapses can recur.
Chronic egg layer
A chronic egg layer produces a larger than normal clutch or it produces repeated clutches, regardless of the existence of a suitable mate or the season. Without extraordinary nutritional measures, chronic egg production leads to a depletion of body calcium and protein stores which can lead to egg binding, dystocia, and weight loss.
A chronic egg layer often requires supportive care and an improvement in its nutritional plane. Halt egg laying by providing environmental or behavioral modification techniques.
- Human(s), toys, mirrors, or birds of other species in the household may serve as substitute mates. Ideally mates, real or imagined, should be removed from the environment. Even exposure to the song of their mate has been found to stimulate cockatiel hens.
- Remove any object which may stimulate masturbatory behavior or regurgitation such as a mirror, favorite toy or nest box.
- Leave eggs in the cage as long as possible. Most parrots are indeterminate layers, which means they will continue to lay eggs that are removed from the nest in an effort to achieve a specific clutch number.
- A drastic reduction in photoperiod can also prove helpful, particularly in the cockatiel. Provide eight to ten hours of light for several days or up to a couple of weeks. Maximal photostimulation occurs with 12 to 14 hours of light, although normal egg laying can occur between 12 to 18 hours. Long day length does not need to be continuous as long as light occurs during the photosensitive phase, which typically occurs approximately 13 to 17 hours after the onset of dawn. Therefore adherence to this short photoperiod must be strict.
|Table 1. Medical therapy of reproductive tract disease|
|Calcium glubionate (Calcionate syurp, Watson/Rugby)||150 mg/kg||PO||q12h|
|Calcium gluconate (Fort Dodge)||50-100 mg/kg||SC, IM||Dilute parenteral calcium in a 1:1 ratio with sterile water or 0.9% saline.|
|Chorionic gonadotropin (Pregnyl, Organon, Inc.)||500 IU/kg||IM||Days 1,3, and 7|
|Dinoprost tromethamine||see prostaglandin F2 alpha|
|Lactulose (Cephulac, Marion Merrel Doug)||200 mg/kg(0.3 ml/kg)||PO||q8-12h||Stool softener in birds with prolapse stay sutures|
|Leuprolide acetate (Depo Lupron, TAP Pharmaceuticals)||100-200 µg/kg||IM||q2-4 weeks||Much higher doses have also been reported: 700-800 µg/kg for birds ≤ 300g or 500 µg/kg for birds > 300g|
|Meloxicam (Metacam, Boehringer Ingelheim)||0.2-0.5 mg/kg||PO, IM, SC||q12-24h|
|Oxytocin (Oxytocin, Butler)||0.5-5.0 IU/kg||IM, SC||May repeat q30 to 60 min||Use should be preceded by calcium; contraindicated unless uterovaginal sphincter is well dilated and uterus free of adhesions; should not be used if egg looks overly large or laminated|
|Prostaglandin E (Prepidil, Pharmacia and Upjohn)||0.2 mg/kg or 0.1 ml/100g||Topical||Relaxes the uterovaginal sphincter; enhances the action of oxytocin and PGF2alpha; may be frozen in aliquots; thaw just prior to administration|
|Prostaglandin F2 alpha (Lutalyse, Upjohn)||0.02-0.1 mg/kg||IM||Once||Use should be preceded by calcium; Should not be used if egg looks over large or laminated; Seems to stimulate more potent contractions than oxytocin, but associated with risk of more adverse effects in mammals|
|Vitamin D3||3000 IU/kg||IM||once or q7d|
|Vitamin E/ selenium (Bo-SE, Schering Plough Animal Health Corp)||0.06 mg/kg||IM||Once or q7d|
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