Susan L. Clubb, DVM
Rainforest Clinic for Birds and Exotics, Inc., Loxahatchee, FL, USA
OVERVIEW OF ISSUE
Veterinary reproductive evaluation, with endoscopic exam is an important tool for aviculturists in evaluation of new breeding stock as well as evaluation of stock with poor reproductive performance. Reproductive assessment is an important service that avian veterinarians can provide to aviculturists. Aviculturists should utilize these services when purchasing new breeding stock for their collections (especially if being sold as proven pairs), evaluation of pairs which have not been producing after 2 to 3 years in a proper avicultural set-up, and evaluation of birds with declining reproduction. (Speer, 1991)
Biopsy of the gonads is a useful adjunct, especially in males as biopsy of the testes can differentiate chronic orchitis with fibrosis, which can result in infertility from reversibly inactive testes.
OBJECTIVES OF THE PRESENTATION
- Present utility of endoscopic exam to reproductive evaluation.
- Present evaluation criteria for the assessment of new breeding pairs and pairs in declining production.
- Assessment of environmental and husbandry factors which may affect reproduction.
- Present the use of gonadal biopsies as a diagnostic and prognostic tool.
KEY CLINICAL DIAGNOSTIC POINTS
Ideally in assessment of a pair, both the male and the female should be examined. Aviculturists often mistakenly choose to examine only the male for example in the case of infertile eggs.
If possible the veterinarian should be acquainted with the housing, husbandry and diet of the pairs to assist in detecting husbandry deficits that may result in reproductive failure. Reproductive assessment should include obtaining as much history as possible about the pairs to aid in diagnosis and formulating recommendations.
Assessing Newly Purchased Pairs
Individual birds as well as pairs of birds are frequently offered for sale as breeding stock. Frequently they are offered as proven pairs. Pre or post purchase examination of such birds is a very important safeguard for the aviculturist. Ideally finalization of the transaction should hinge on the veterinary exam. Culling of non-productive stock is a common means of enhancing avicultural productivity. Parrots can live and appear in very good condition for years after their reproductive potential has diminished. Pairs that are senescent, or in declining production can honestly be sold as proven breeders even though their future breeding success may be questionable.
Unscrupulous aviculturists often prey upon new or naive aviculturists by selling supposedly proven breeding birds that may turn out to be very old, or not even true pairs. To avoid the costs of reproductive exam aviculturists often do their own diagnostics--checking gender by DNA analysis of blood or feathers. However this type of evaluation provides only a small portion of the information that can be obtained by a veterinary reproductive exam.
It is a common practice for veterinarians to remove closed bands from pet birds. These birds often end up in avicultural collections. If you remove a closed band you remove the identity from a bird that may be very important in the future. If properly fitted, closed leg bands seldom cause entrapment injury.
Open bands can indicate that a parrot was wild-caught and imported. If the bird entered thru a USDA approved commercial quarantine station the band will have three letters and three numbers (example FIX-333). Any birds with such a band would have been imported no later than 1993. The Wild Bird Conservation Act went into effect in late 1992 and allowed one more year of declining imports before they ceased. So any parrot so banded would be at least 15 years old, unless it was banded with such a band after entry. In these band codes the first letter indicated the state of entry (C and O being California, F being Florida, L being Louisiana, H being Hawaii, I being Illinois, M being Michigan and N being New York). The second letter in the 3-letter code was an indication of the USDA licensed quarantine station. Since California at one time had more than 24 licensed quarantine stations the letter code "O" was added for California stations. The third letter in the code was a part of the number code, making it alpha numeric with 24,000 possible combinations before it repeated. To obtain more information on when a bird was imported the USDA can be contacted and might be able to trace it. This is important because many wild-caught birds initially placed in breeding collections are now becoming aged. Many are resurfacing and being resold as their reproductive capability declines.
If no information as to age is available the veterinarian can make an educated guess by looking at the face, eyes, feet, skeletal structure (posture, etc,) and endoscopic examination of the gonads.
Thinning of skin especially around the face and eyes, very scaly feet and deformed nails, arthritic feet or other joints, eye color changes, cataracts, slouching posture, lateral rotation of the carpus can all be hints of advanced age. The plumage of parrots does not gray with age. Their plumage color remains brilliant if health and diet are adequate.
An endoscopic exam of newly purchased breeding stock is essential to detecting reproductive problems or assessing reproductive capability. It is also helpful in assessment of general health.
Veterinarians are often reluctant to make a prediction of reproductive viability unless sterility can be obviously demonstrated. Breeding readiness and gonadal activity is fluid and can change if husbandry deficiencies are corrected.
Assessing Non-Producing Pairs or Pairs in Declining Production
Assessment of poorly producing pairs must include evaluation of husbandry, unless it is known to the veterinarian that the aviculturist is knowledgeable and experienced. Examine health and weight records if available for additional clues.
Some husbandry problems that might cause poor reproduction, or reproductive failure include: Inadequate or inappropriate diet, caging, nest boxes, or perches. Diets that are appropriate for pet birds may not be stimulatory for breeding birds. Cyclic or flush feeding, diets higher in protein and fat and special supplements may be indicated for birds in production.
Size, construction material, and placement of caging may influence reproduction.
Consider the effects of neighbors, traffic, and disturbances. Vermin can profoundly affect reproduction. Consider the effects of rodents, cats, dogs, raccoons, ants, mosquitoes or other biting insects. Weather conditions may be contributory, especially if a large portion of the flock is not producing as expected. Sanitation, water quality and food hygiene can also have a profound effect on flock health and production. Nest boxes should be appropriate size and construction for the species. Nest material should be dry, of adequate quality and depth, and clean. Birds that soil their nest boxes tend to have relatively poor reproductive potential. Excessive heat in nest boxes, or boxes which leak or are too moist can be a major problem. Perching must be adequate in size, types, stability and placement for successful copulation.
Compatibility of the pair should be evaluated. Mate aggression is a major problem in some species. Male aggression toward females is well known in cockatoos and amazons. But female aggression directed toward the male can also be a problem in Eclectus parrots, Buffons Macaws and many Asian parakeet species.
Endoscopic examination can assist in detection of unrecognized stressful conditions by evaluation of the adrenal gland. Some pairs simply don't like each other. Pairs in which the birds are always sitting at opposite sides of the cage are unlikely to have good production. If the heads are not preened this is another sign of incompatibility. Ideally the pair should sit together, enter or defend the nest box together, engage in allopreening and eat together peacefully. If the pair approaches and attempts to attack the caretaker together, this is a good sign of a strong pair bond good reproductive potential. Ask the aviculturist if the pair enters the nest box, "works" the nest, and in general appear to be compatible. Sometimes a bird might pair with a neighboring bird, or males in adjoining cages might spar which can affect production.
Placement of the cage in the aviary, yard or home may also have an impact if the birds are distracted, disturbed, agitated, too exposed, too enclosed or sheltered, too close to areas of high activity, too hot, etc. An extensive knowledge of the species involved is required to adequately evaluate many of these factors. Observation is also critical.
Detection of sub clinical health problems can be revealed during the reproductive exam, but it is important to also look for problems that could specifically affect reproduction. Thorough examination under anesthesia may help to reveal oral problems such as papillomas, tumors, vitamin deficiencies or infections. Keel scoring and recording of body weight can be important in determining if obesity or low body weight is a factor. Carefully examine feet and legs for signs of excessive wear or ulceration, constricted toe syndrome, arthritis of the feet or leg joints, overgrown nails or other physical condition which may affect copulation.
Examination of the cloaca should include eversion to detect papillomas or other abnormalities of the cloaca and evaluation of fat pads that might preclude proper positioning for insemination. In a reproductively active female the cloaca will be flaccid as hormonal stimulation readies the hen for laying.
Endoscopic evaluation should include evaluation of all organs, not just the gonads. Undiagnosed air sac disease, anthracosis, enlargement of the proventriculus, hepatic disease, renal disease etc may impact reproduction. If the endoscopy site is lateral, behind or between the last ribs, soft ribs, indicating calcium deficiency can be detected.
Endoscopic evaluation of the female should include recording of descriptions or rating of the size of the stroma of the ovary, the size and relative number of follicles, the presence of ovarian cysts, the relative accumulation of caseous material or scarring at ovulatory sites. The oviduct should be evaluated for level of hypertrophy or activity. The distal pole of the ovary where the fimbrium of the oviduct is located should be evaluated for any possible blockage. The adrenal gland is usually not visible in a mature female parrot. If it can be visualized this may be an indication of an undersized or inactive ovary or excessive stress resulting in adrenal enlargement and possibly reproductive suppression. Finding of a thickened membrane overlying the ovary may indicate inflammatory disease. Finding of a very small stroma or presence of excessive amount of white scar tissue may indicate senescence. Interestingly older female parrots may have low fertility, or viability of ova but they can still successfully produce eggs. In fact many older females, especially macaws, will produce larger number of eggs than young females, and still have a low rate of fertility despite being paired with a fertile male.
If a female is very near to laying, visualization and evaluation of the ovaries is very difficult if not impossible. Enlargement of the oviduct displaces organs and large follicles ready to ovulate may be easily damaged. Endoscopically these hens will look very abnormal, possibly ill. If the bird has an enlarged abdomen and flaccid vent any further diagnostics should be delayed until she is given the opportunity to lay.
Biopsy of suspicious tissue may be helpful however biopsy does not seem as helpful in evaluation of females as in males. Some potentially useful findings include the presence of inflammation or fibrosis of the gonad. For example the presence of fibrosis suggests replacement of functional gonadal tissue. Excessive fibrosis will render the animal infertile. (Clubb 2002, Crosta 2002, Crosta 2003)
Ovarian or oviduct infection is a common cause of infertility, embryonic mortality and weak, sick chicks at hatch. The easiest way to diagnose oviduct infection is to culture eggs. To introduce a swab into the orifice of the oviduct is very difficult and potentially harmful. Hens that are laying large numbers of eggs seem to be predisposed to ascending oviduct infections.
Endoscopic evaluation of the male should include recording of the relative size, color, density and shape of the testes. The relative size of the adrenal gland (does it appear enlarged) and a ratio of size of the adrenal to the testes should be recorded. For example if the adrenal gland is the same size as the testicle this would be a 1:1 ratio. Unless the bird is very young, this would not be a favorable finding; indicating that either the adrenal gland is enlarged or the testes are very small. Depending on the species and time of the year a good male may have a ratio of 1:3 or more. If the testes are very active (again depending on the species) the adrenal gland is not visible at all, of the ration may be 1:6. The adrenal: testicular ratio is very useful for comparison of males within a collection to determine which is most active.
The surface of the testes should be evaluated for smoothness and degree of vascularization. Wart- like structures on the surface may be dilations of the seminal vesicles that may or may not affect reproduction. The epididymis should be examined if visible. The vas deferens should be examined for possible blockage. Thickened, proliferative or excessive membranes surrounding the testes may be an indication of airsac infection or inflammatory disease that may affect the testes.
Enlargement of the adrenal gland and a high adrenal: testicular ratio can indicate excessive stress and suppression of reproductive performance by endogenous glucocorticoids. This is a common finding in non-productive males. The density of the testes can be an indication of fibrosis. A mature and active testicle should not only be enlarged but should have a translucent, almost fluid filled appearance. A highly vascularized testicle, or a testicle in which the tissue appears pink or red can be a sign of orchitis. Orchitis appears to be a common cause of male infertility in psittacine birds.
A mature and active testicle should not be biopsied. Such a testicle can explode or leak releasing spermatozoa into the body cavity. If the testes appear small and inactive, especially if it appears very dense-indicating fibrosis, or very inflamed, biopsy may be indicated to document whether the testicle is simply inactive and fertility reversible or fibrotic and irreversibly infertile.
If on physical and endoscopic exam the female is in good reproductive condition but the aviculturist reports finding no eggs, the pair may be eating eggs. This is especially common with captive bred parrots. Aviculturists often report finding no evidence of egg eating (no shell fragments in the nest box) however this does not eliminate the possibility of egg eating. By closely monitoring the cycle of each hen and checking the nest box in the early morning and late afternoon the aviculturist may be able to collect the eggs before they are eaten.
Veterinary exam including endoscopy can provide insight into psittacine reproductive failure. When coupled with assessment of husbandry, age and other important factors the veterinarian can assist the aviculturist in diagnosis of reproductive failure. Repairing of birds, careful observation of pairs that eat eggs and correction of husbandry deficiencies can enhance production.
1. Clubb S, Zaias J, Cray C, Berube L, Crosta L. Endoscopic testicular biopsies for evaluation of fertility in Psittacine birds, Proc of AAV, pp. pp 133-137, Monterrey, CA, 2002.
2. Crosta L, Gerlach H, Burkle, Timossi L. Endoscopic testicular biopsy technique in Psittaciformes, J Avian Med. Surg. 16(2), 106-110, 2002.
3. Speer BL.A clinical approach to psittacine infertility: Proc Annu Conf Assoc Avian Vet, 1991: 173- 187
Susan L. Clubb, DVM
Rainforest Clinic for Birds & Exotics Loxahatchee, FL, United States