M. Scott Echols, DVM, DABVP (Avian)
Primarily due to high egg producing hens, avian reproductive tract disease is very common in pet and even commercial avian practice. With the advancements in diagnostics and therapeutics available to birds, many reproductive tract diseases can be medically managed. However, several diseases can only be treated surgically. Because of past literature describing procedures such as salpingohysterectomy as "difficult and risky," many practitioners are rightfully cautious about performing avian reproductive tract surgery. As with diagnostics and therapeutics, anesthetic techniques, instrumentation, a better understanding of respiratory physiology and surgical techniques have all advanced in birds. Now with the progression and public awareness of these "advancements," avian practitioners are being called upon to perform more difficult surgical procedures in birds and with greater success than ever.
Surgical instrumentation, surgeon technique, managing anesthesia, post-surgical care and analgesics are well-deserved topics, but are covered elsewhere in the literature. Although not stated under each surgical procedure, analgesics should be considered in all surgical cases.
Approaches to the Avian Reproductive Tracts
Since reproductive tract surgery typically involves puncturing through one or more air sacs, any notable fluid present should be removed prior to surgery. Fluid escaping from self-contained peritoneal cavities into a surgically incised air sac may enter the respiratory system and cause life-threatening respiratory disease. Prior to reproductive tract surgery, coelomocentesis should be performed in birds with coelomic fluid. Upon entering the coelomic cavity, any remaining fluid can be aspirated using a red rubber feeding tube, mini-suction unit, or via butterfly catheter to better clear the surgical field and reduce the chance of aspiration. A left lateral or ventral midline celiotomy is typically used to approach the avian female reproductive tract.
Female Reproductive Tract Surgery
Understanding the avian female reproductive tract anatomy, especially its blood supply and drainage, is vital to performing surgery. During sexual and egg laying activity, blood supply to the ovary and oviduct can be significant. Due to the potential vascularity, respecting the local blood supply and minimizing bleeding can often determine the outcome of the patient. Focus will be given to the basic structure and vasculature of the ovary and oviduct. If possible, the following surgeries should be performed when the female is reproductively inactive as blood supply is often reduced.
Surgery of the Avian Ovary
Ovariectomy in hens has proven to be a challenging and oftentimes high-risk procedure. Ovariectomy has been used in many poultry studies and mention of this procedure can be found throughout the literature. Unfortunately, most papers poorly describe the specific details of the ovariectomy or its complications.
Although it has been stated that the short stalk of the cranial renal artery is what makes ovariectomy difficult, the author suggests that the intimate and lengthy attachment to the overlying common iliac vein is what makes this procedure risky. As discussed under "Anatomy of the Avian Ovary,"* multiple small veins often connect directly into the common iliac vein. It is often venous, and not arterial, bleeding from a lacerated common iliac vein that usually causes life-threatening hemorrhage during ovariectomy. As with the oviduct, the ovary can dramatically change in size and vascularity with sexual and egg laying activity. As a result, every attempt should be made to medically or behaviorally "turn off" the bird's reproductive activity to reduce the vascularity to the ovary. Oftentimes, diseases requiring ovariectomy do not allow attending clinicians time to "condition" the avian patient prior to surgery.
Ovariectomy should be reserved for ovarian diseases such as cancer, chronic recurring cysts, persistent follicular activity, oophoritis and other diseases that cannot be managed medically and are life-threatening without further treatment. While some birds such as cockatiels appear to stop ovulating after the salpingohysterectomy, other species such as ducks may continue chronic and possibly life threatening ovulation necessitating hormonal therapy or ovariectomy.
The first step to ovariectomy is to debulk its mass, regardless of size. The goal of this first step is to be able to visualize the ovarian attachment to the overlying common iliac vein and any other vessels present. If the ovary is inactive or juvenile, very little debulking is needed. If present, remove large preovulatory follicles as discussed under "Salpingohysterectomy"*. Aspirate and drain any cystic follicles present being careful not to spill contents into the coelomic cavity, especially if there is concern of oophoritis. When aspirating follicles, guide a small gauge (23–25 g) butterfly catheter needle into the most visibly avascular portion to reduce hemorrhage and have an assistant provide distant suction. Using this aspiration technique, a significant amount of an active and/or cystic ovary can be debulked. As a note, blood filled follicles may represent previously ruptured blood vessels from an invasive mass and warrants caution when attempting debulking.
Alternatively, large ovarian follicles can be twirled using cotton tip applicators. Use the cotton tip applicators to rotate the follicle in one direction continuously until it separates from its pedicle. This may require 15–30 full rotations until the follicle is free. Once free, simply remove the follicle.
Once the fluid component is minimized, progressively clamp or hemoclip the ovarian mass closer to its base. When used properly, Angled Debakey neonatal vascular clamps are atraumatic, will rest in the surgical site without obstructing view and seem to provide some hemostasis to the ovarian mass. Once a section of the mass is hemocliped or clamped, surgically excise or cauterize and remove the ventral-most ovarian segment. Reassess the mass and move the clamp (or place new hemoclips) closer to the base and repeat the excision process. This process is repeated until the overlying vasculature is clearly identified and the course of the common iliac vein can be seen.
Once the mass has been debulked, several options exists for complete or partial ovariectomy. Altman reports effectively using an electrocautery ball electrode to coagulate ovarian follicles in immature females. The same procedure results in ovarian regeneration and subsequent ovulatory activity in mature hens. The author has noted that some juvenile bird ovaries can be gently "peeled" in toto from caudal to cranial off its dorsal attachments with no or minimal bleeding. In these cases, the caudal end of the ovary is grasped with angled hemostats and pulled in a cranial direction with a clear separation, and minimal effort, from the dorsally located common iliac vein. If attempting this procedure, stop if any resistance is noted to prevent tearing the overlying vein.
Another technique with juvenile or sufficiently debulked ovaries is to place hemoclips in the potential space between the ovarian base and the common iliac vein. Gently lift the caudal pole of the ovary and place a small to medium hemoclip from caudal to cranial across the ovarian vascular supply. Although difficult without good exposure, a last hemoclip can be placed from cranial to caudal in the same manner in attempt to ligate the more cranially located ovarian artery. With the blood supply adequately clamped, the ovary can be gently shaved off with precise radiosurgery using an Ellman B "loop" series or blade electrode (Ellman International, Inc., New York, NY, USA) or left to die without a blood supply. Altman describes this method as "a difficult, high-risk procedure" but the author has successfully performed ovariectomies in adult hens using this technique. Obvious complications include hemorrhage when trying to remove the hemoclipped ovary and inadequate, blind, placement of the hemoclips.
The author has used another approach when the ovarian attachment to the overlying common iliac vein is too long to hemoclip or there is erosion into the overlying vessel and the entire ovary must be removed for the bird's survival (as with otherwise untreatable cancer). Debulk the ovarian mass as described above. Once clearly identified, hemoclip the common iliac vein just caudal to the ovary and cranial to its junction with the caudal renal vein. Next, hemoclip the common iliac vein just cranial to the ovary and caudal to its junction with the caudal vena cava. If done properly, the ovarian artery and common iliac veins are effectively clamped allowing one to carefully dissect the entire ovary from the overlying vessel(s). If needed, the ventral wall of the common iliac vessel can be safely removed. There is the real potential of damaging the left adrenal gland, significantly altering blood flow through the renal portal system and the cranial renal division and causing physical damage to the overlying kidney and lumbar and/or sacral nerve plexus(es).
With all of the above described ovariectomy procedures, it should be understood that none have been satisfactorily studied in pet bird species and that each caries a significant risk to the patient. With each procedure, closure is routine. More often, a partial ovariectomy is performed and only the abnormal ovarian tissue is removed.
Surgery of the Avian Oviduct
Salpingohysterectomy is the surgical removal of the oviduct, infundibulum to uterus, is indicated for chronic egg laying and any oviduct disease that cannot be medically managed and is reported as the "therapy of choice for overproduction of eggs." Every attempt should be made to understand the bird's overall health status prior to surgery, as the patient should ideally be stable. Birds with septic yolk peritonitis generally carry a poor prognosis. Patients with underlying health problems such as various lung, liver and kidney diseases can also complicate surgery. Otherwise healthy salpingohysterectomy candidates typically do well and surgery is often straightforward especially when the oviduct is small and inactive. Oviductal hypertrophy occurs secondary to elevated estrogen levels during sexual activity and can take up most of the left side of the intestinal-peritoneal portion of the coelomic cavity. This oviductal hypertrophy includes increased vascularity and risk of bleeding during surgery. If the patient is stable, time permits, and increased reproductive tract vascularity is suspected, the author will "condition" the bird prior to surgery. "Conditioning" includes improving nutritional status (if necessary) and attempting to turn off the bird's sexual cycle as described under "Egg Binding and Dystocia." This process may take weeks to months and often results in decreased vascularity and lower patient morbidity.
Perform a left lateral celiotomy. After incising through the left abdominal air sac, the ovary and oviduct are readily visible. Gently retract the cranial oviduct (infundibulum area) out the incision and hemoclip or cauterize suspensory ligament vessels as needed. The closer the bird is to laying, the larger the vessels present. Depending on the size, the cranial, middle and/or caudal oviductal artery(ies) may need to be hemocliped or cauterized. Once visualized, hemoclip the base of the oviduct just proximal to its junction with the cloaca. Excise the oviduct.
Well-developed preovulatory follicles (F1 and F2 +/- F3 and F4) may pose a risk for intra-coelomic ovulation and can usually be easily removed as described in "Surgery of the Avian Ovary". If the follicle has a well-developed vascular pedicle, use hemoclips and then excise the follicle or twirl the follicle. One study in domestic chickens demonstrated a pause in laying that increased with the number of follicles removed compared to sham operated hens.
Cystic follicles should either be aspirated (drained) or removed. If the follicle is accidentally incised, yolk will leak into the coelom. Simply "mop up" excess yolk and other fluid if present. Collect culture and samples for histopathologic evaluation as needed.
An endoscopic approach to salpingohysterectomy of juvenile cockatiels has been described. Endoscopy has long been used as a sex determination and biopsy tool, but gross endoscopic surgery in birds is relatively new. A left lateral coelomic endoscopic approach (left leg pulled caudally) was performed on juvenile (3–11 month old) cockatiels. Once visualized, the supporting ligament of the infundibulum was carefully pulled laterally toward the coelomic entry site using flexible endoscopic grasping forceps (Karl Storz Veterinary Endoscopy, Inc., Goleta, CA, USA). This action broke down the supporting structures (ventral and dorsal suspensory ligaments of the cranial oviduct and uterus) and separated the salpinx (oviduct) from the overlying kidney, caudal vena cava and left ureter. Next, a cotton-tipped applicator was placed in the cloaca and was used to better visualize the uterus-cloacal junction and ensure the salpinx was "peeled" from the surrounding tissues. The salpinx was exteriorized and then crushed and cut with microsurgical forceps and scissors, respectively, at the point of exit from the coelomic cavity, just cranial to the uterovaginal sphincter. The endoscope was replaced to check for hemorrhage and closure was routine.
The endoscopic salpingohysterectomy has several distinct benefits and limitations. As indicated in the study, this procedure was acceptable in the juvenile birds due to a poorly developed blood supply of the oviduct and that if attempted in mature, egg producing cockatiels, may result in fatal hemorrhage. Additionally, this procedure required an endoscope and two surgeons. Although the endoscopic surgery was limited to young birds, there was minimal hemorrhage and could be performed safely and quickly (estimated to take less than 10 minutes with experience) and offers an option for juvenile salpingohysterectomy.
Caesarian Section and Reproductive Tract Sparing
Caesarian section is indicated when the bird's reproductive capabilities need to be spared and is typically limited to egg binding with an otherwise normal, or minimally diseased oviduct. Depending on the location of the egg, a caudal left lateral or ventral midline approach is used. The oviduct should be incised directly over the bound egg and away from prominent blood vessels. After removing the egg, inspect the oviduct for other abnormalities and collect biopsies and cultures as needed. Close the oviduct in a single simple interrupted or continuous layer using fine (4-0 or smaller) absorbable suture material. Coelomic closure is standard. The author recommends resting the hen from reproductive stimuli for two to four weeks or longer as dictated by culture and/or histopathologic results.
Diseases of the ovary and oviduct and potential surgical treatments will be discussed during the presentation.
This manuscript was adapted from the chapter "Surgery" by M. Scott Echols, DVM, DABVP(Avian). In: Backyard Poultry Medicine and Surgery: A Guide for Veterinary Practitioners. Edited by Cheryl B. Greenacre, DVM, DABVP(Avian) and Teresa Y. Morishita, DVM, MPVM, MS, PhD, DACPV. Published by Wiley (in press).
References are available upon request.