Diagnosing diseases that target certain pet bird species (Proceedings)

Proventricular Dilatation Disease (Macaws, Conures, others)

This presentation focuses on a disease proventricular dilatation disease (PDD) that many people have heard about, may have had bird's affected, but know little about. The same may be said for veterinarians. It is especially frustrating for the veterinary community to know enough to diagnose a disease but have no means of prevention or treatment against the organism responsible. This is because we do not know what organism is responsible. This is evidence that a virus is the cause of the disease but its identification is still elusive. A short history of PDD shows that it was first identified in the late 1970's associated with imported psittacine species in the U.S. and Europe. A number of avian species have been identified as being susceptible to PDD including over 50 psittacine species. Common pet birds in which PDD has been diagnosed include, African grey parrots, cockatiels, conures, lovebirds, Amazon parrots, cockatoos, eclectus parrots and macaws.1 No reports of the disease have been documented in wild psittacine birds living in their native environment but it does not appear that they would free from contracting PDD. PDD has been diagnosed in birds ranging in age from 10 weeks to 17 years with the average age of infection being 4-5 years.1 Another major problem with PDD is that it can invade the best of aviaries because of its random occurrence and potentially long incubation time. An infected African Grey parrot had no direct contact with other birds for 4 years. We have had young cockatoo's, less than 6 months old, develop clinical neurologic signs (e.g., twisted head, vocalization, unable to perch) and die within 2 to 3 weeks. The medical community does not know what causes the disease or how long the incubation period is before signs are observed. We know that it may can be a very fast disease in young birds and very slow in older birds with many variations. Owners may notice PDD birds lose body condition despite a very good appetite, delayed crop emptying, neurologic signs as mentioned before and passing undigested food in the feces. If a bird has one or more of these signs how is a definitive diagnosis obtained? A radiographic image of an enlarged proventriculus is not definitive for proventricular dilatation disease. A veterinarian must take a biopsy of the crop, including a blood vessel in the biopsy sample, for a definitive diagnosis. This does not always determine if the bird is suffering from PDD. A biopsy of the adrenal gland has also been advocated as an option for diagnosing PDD. Once diagnosed, every case is different in options, and these should be discussed with your veterinarian. In older birds with less severe disease conditions supportive care, including the use of anti-inflammatory therapeutic medication (Celecoxib, Celebrex®), has shown promise in treating PDD patients.

Proventricular dilation disease is a serious disease, not necessarily because of what we know, but what we do not know. We do not know if in fact it is caused by an infectious agent (highly suspect), if it is a slow progressive disease, if there is a long incubation period, if infectious how is it transmitted or preventive measures. All we can do as veterinarians is to inform bird owners what we know and review each case as they are diagnosed. Bird owners can try and maintain good aviculture management and bird health oversight. As I have stated this does not guarantee that PDD will not strike your birds but it sure will help reduce the odds of major disease outbreaks over and above the subject of this article.

Feather Picking (African Grey Parrots, Amazon Parrots, Macaws, others)

Self-induced feather loss in companion birds is one of the most common and frustrating avian case presentations. There are a number of causes for feather loss and these cases require a thorough investigative work-up by the attending veterinarian. Differential diagnoses for feather picking birds include hypersensitivity, environmental and nutritional causes and psychological.

Initial treatment is based on history, clinical presentation and diagnostic test results. If a disease process is identified as a primary cause of the feather loss then it is appropriately treated. If it is determined that the self-induced feather loss is psychological the other medications are prescribed. We start with the anti-depressant and hope that treatment is effective. If we decide that the bird should be treated with the anti-psychotic medication we have a conference with the owner explaining the serious side affects that may be noted with its use. We never place a patient on a concurrent anti-depressant and anti-psychotic treatment regime.

Psychological Medications

1) anti-depressant: Nortriptyline HCL (Aventyl HCL, Lilly) syrup 2 mg/ml

Dose: 1 ml/4oz drinking water

2) anti-psychotic: Haloperidol (Haldol, Henry Schein) solution 2mg/ml

Dose: 0.2 mg/kg BID for birds < 1 kg

0.15 mg/kg SID-BID for birds > 1kg

NEVER ADMINISTER TO HYACINTH MACAWS – TOXIC

If we feel the case may be the result of an environmental hypersensitivity there is another treatment protocol that we commonly use. This treatment is listed below and is given concurrently to the patient.

1) Hydroxyzine HCL (Barre-National) 10 mg/5 ml

Dose: 0.1 ml/100grams body weight SID

2) Liquid Fatty Acid (Pfizer)

Dose: 0.1 ml/100 grams body weight SID

Reproductive Presentations (Cockatiels, Budgerigars, Ducks, others)

Treating disease problems effecting the avian reproductive tract is often much easier than investigating management or compatibility issues. Egg binding or dystocia is arguably the most common reproductive disease process seen by veterinarians.2 The definition of dystocia has been published as the mechanical obstruction of an egg in the caudal reproductive tract, at the level of the caudal oviduct/uterus, the vagina, or the vaginal-cloacal junction.3 Causes of dystocia or egg binding has been hypocalcemia and nutritional deficiencies, oviduct, uterus, or vaginal muscle dysfunction, excessive egg production, large, misshapen, or soft-shelled egg(s), age of hen, obesity, oviduct tumor, oviduct infection, lack of exercise hyperthermia or hypothermia and genetics.2 When a patient presents and has been diagnosed with dystocia it is imperative that stabilization of the bird occur as soon as possible. That would include fluid therapy, intramuscular calcium injection, vitamin A and D3, nutritional supplementation if need and placement into a heated, humidified intensive care unit. Once the patient is stabilized, removal of the egg should be contemplated, either helping the bird expel it herself or manual removal through direct veterinary intervention. Prostaglandin E2 (PGE2) relaxes the uterovaginal sphincter and increases uterine contractions.4 The application of 0.1 mL/100 gram body weight of PGE2 gel (Prepidil;Pharmacia and Upjohn, Kalamazoo, MI) directly into the dorsal area of the cloaca contacting the uterovaginal sphincter may help promote egg delivery. In optimum circumstances Prepidil will initiate uterine contractions that expel the egg within 15 minutes of application.4 Oxytocin targets the uterus but does not relax the uterovaginal sphincter and is inferior to PGE2.4 Ovocentesis or aspiration of the egg contents can safely be performed on eggs visible in the caudal 1/3 of the oviduct while surgical removal is only recommended in life threatening situations. To prevent egg binding from reoccurring it is recommended to give leuprolide acetate (0.375 mg IM in cockatiels), a mammalian LHRH (GnRH) that reduces serum gonadotropin levels by reducing the number of LHRH receptors in the pituitary.2 Leuprolide acetate has been effective in delaying egg laying from 19 to 28 days.

Prolapsed oviduct out of the cloaca commonly occurs when there is difficulty passing the egg through the terminal part of the reproductive tract. The exposed reproductive tract becomes desiccated adhering to the egg. Many of these cases can be resolved by hydrating the exposed reproductive tract and slowly manipulating the egg through the uterovaginal sphincter. Replacement of the oviduct, once the egg is removed and application of a topical medicated, is often sufficient in remedying the problem. Reoccurrence of prolapsed oviduct is rare in our practice.

Egg yolk peritonitis occurs when ovulation takes place outside of the oviduct into the coelomic cavity. Ectopic ovulation is often noted secondary to reverse perisalsis, salpingitis, metritis, neoplasa, cystic hyperplasia, ruptured oviducts, and stress or physical restraint of the egg-laying hen. Treatment requires patient stabilization and confirming the diagnosis. Confirmation of egg yolk peritonitis can be made through cytologic evaluation of cellular debris from a coelomic aspirate, radiology and a complete blood count. The patient usually presents depress with an enlarged caudal ventral coelomic cavity. Many patients are diagnosed with concurrent adhesions involving the intestinal tract and other major organs. Surgery, including a salpingiohysterectomy is difficult when trying to address the significant pathology associated with peritonitis. Chronic egg yolk peritonitis is considered the most common fatal reproductive condition in avian speices.2

Chronic egg laying, commonly occurs in cockatiel hens, is a life threatening problem. It is recommended to try behavior and dietary modification before therapeutic measures are used. If behavior and dietary modifications are not successful then leuprolide acetate (0.375 mg IM in cockatiels) (Lupron; TAP Pharmaceuticals, Deefield, IL) is the therapeutic drug of choice.2 Cockatiels should be injected every 18 days while budgerigars are injected every 12 – 14 days.

Bacterial infections affecting the ovary, oviduct and cloaca can cause reproductive abnormalities. Obtaining the results from an ill avian patient which includes a complete blood count, culture and sensitivity of a reproductive tract or cloacal culture will aid in the diagnosis of a reproductive tract infection. Reproductive tract infections may be secondary to neoplasias of the ovary or oviduct. Ovarian neoplasia has been diagnosed in budgerigars but not often seen in other parrot species. There is currently no treatment for ovarian or reproductive tract tumors.

Reproductive disorders that are diagnosed in pet birds are presented to the teaching hospital on a regular basis. By performing the proper work-ups the reproductive disorders can be diagnosed and treated, hopefully perpetuating the species for future generations to enjoy.

References

1. Gregory CR: Proventricular dilatation disease. In: Ritchie BW. Avian Viruses Function and Control. Wingers Publishing, Inc. Lake Worth, Florida. 1995. 439-448.

2.Romagnano A. Avian obstetrics. Semin in Avian and Exotic Pet Medicine. 1996;5:180-188.

3.Speer B. Clinical reproductive avian medicine, in foundations in avian medicine. Proceedings of the Assoc. of Avian Vet. Philadelphia, PA.1995;23-33.

4.Hudelson S, Hudelson P. Egg Binding, hormonal control and therapeutic considerations. Compend Contin Edu 1994;15:427-432.