Pathology of aging psittacines

Pathological findings and their association with diseases of captive psittacine birds native to Mexico

The captivity and use of native psittacine birds is prohibited in Mexico. However, as these birds are among the groups most affected by illegal trafficking, they are commonly found as companion animals. Nevertheless, it is difficult to obtain information on their health. Therefore, a retrospective study was conducted of the clinical histories and necropsy reports of native psittacines that had been submitted to the Bird Disease Diagnostic and Research Laboratory of the Facultad de Medicina Veterinaria y Zootecnia, Universidad Nacional Autónoma de México, from 2006 to 2017. The lesions were classified according to type and anatomical location and the diseases were classified as infectious or non-infectious. During this period, 252 psittacines were submitted, the most frequent of which were the red-lored parrot (Amazona autumnalis), orange-fronted parakeet (Eupsittula canicularis) and scarlet macaw (Ara macao). The lesions were primarily located in the digestive and respiratory systems. By integrating the clinical histories and post-mortem findings, we concluded that nutritional disorders were the most frequent non-infectious diseases, systemic bacterial infections were the most frequent infectious conditions, the primary parasite was Sarcocystis spp and the most frequent neoplasm was multicentric lymphoma.

Rhabdoid melanoma in a harpy eagle (Harpia harpyja)

A 28-year-old male harpy eagle (Harpia harpyja) with a history of anorexia, hyporexia, lethargy, and progressive weight loss was found dead and submitted for post-mortem examination. Gross findings include dark brown discolouration of testes and lungs; the testes were bilaterally enlarged, glistening brown-grey to blackish in appearance, firm, smooth, and multilobulated. The lungs contained a mass with similar features to the testicles, irregularly shaped with multiple nodules. Histology of testis showed round, polygonal and pleomorphic cells, containing melanin pigments and a typical eosinophilic vacuole in their cytoplasm and with severe pleomorphism. An immunohistochemistry panel with Melan-A, vimentin, CK AE1/AE/3, MUM-1 and CD-68 were performed, yielding a positive reaction for Melan-A and vimentin. The morphology of the tumour cells, the presence of melanin pigment and the immunoreactivity for Melan-A and vimentin by the cells led to a diagnosis of rhabdoid melanoma. This is the first case of this pathology in the testis with lung metastasis in a harpy eagle.

Ocular Examinations and Investigation of Intraocular Pressure, Tear Production, Central Corneal Thickness, and Corneal Touch Threshold in a Captive Flock of Atlantic Puffins (Fratercula arctica)

Ocular examinations were completed on a group of 10 Atlantic puffins (Fratercula arctica), 5 males and 5 females that ranged in age from 8 months to older than 30 years. The exams consisted of intraocular pressure/rebound tonometry, tear production/phenol red thread test, central corneal thickness/ultrasound pachymetry, and corneal sensitivity/esthesiometry. On ocular examination, there were no corneal abnormalities observed. Bilateral cataracts were diagnosed in 8 puffins, 6 of which were considered incipient, focal subcapsular opacities. One bird had hypermature cataracts and was removed from the study and excluded from data analysis; the other birds had no evidence of ophthalmic pathology that would interfere with diagnostic results (n = 9). All results for 9 birds were included in the study, with the exception of 1 puffin's tear production, which was too low for accurate assessment and was excluded from data analysis. There were no significant differences between right and left eye measurements for intraocular pressure, corneal thickness, and corneal sensitivity. The median intraocular pressure for both eyes (OU) was 13 mm Hg with an interquartile range [IQR] of 12-15 mm Hg. The median corneal thickness OU was 241 µm, IQR 233-248 µm. The median corneal sensitivity OU was 1.13 cm, IQR 0.81-1.50 cm. There was a significant difference between right and left eye measurements for tear production (right eye median, 7.5 mm/15 s, IQR 6.5-9.3 mm/15 s; and left eye median, 5.0 mm/15 s, IQR 4.0-7.3 mm/15 s) (P= .03), with the right eye producing more tears than the left. However, 1 puffin was determined to be an outlier, and when removed, there was no longer a significant difference (OU median, 7.0 mm/15 s, IQR 4.6-8.0 mm/15 s) (P = .38). There was no significant difference between sex and intraocular pressure, tear production, and corneal sensitivity. However, there was a significant difference between sex and corneal thickness (P = .02), with males (left eye median, 249 µm, IQR 241-249 µm) having thicker corneas than females (left eye median, 236 µm, 234-238 µm). Although sample size precluded statistical testing, there appeared to be an association between opacities and increasing age. There were no associations between age and intraocular pressure, tear production, or corneal thickness. There was a moderate correlation between age and corneal sensitivity, with older birds showing decreased corneal sensitivity (r = -0.57). Although the sample size of 9 birds was small, these findings provide preliminary ranges for ocular parameters of Atlantic puffins.

Gerontology of Psittacines

With recent improvements in the husbandry, nutrition, and veterinary care of captive psittacines, the avian clinician must be familiar with common medical condition seen in geriatric parrots. A review of the theory of evolution and avian senescence is provided. Five clinically relevant medical conditions are described: organ failure, atherosclerosis, neoplasia, cataracts, and osteoarthritis.

Diagnostic value of plasma biochemistry, haematology, radiography and endoscopic visualisation for hepatic disease in psittacine birds

BACKGROUND

Hepatic disease in psittacine birds is common but challenging to diagnose. This retrospective study evaluates the diagnostic value of plasma biochemistry, haematology, radiography and endoscopic visualisation in psittaciforms with suspected hepatic disease that underwent endoscopic liver biopsy.

METHODS

Clinical records of 28 companion psittaciforms from a veterinary teaching hospital (2007-2016) were reviewed. Diagnostic results were categorised as abnormal or normal and compared with histopathology for agreement or disagreement. Statistical significance was determined by kappa test for agreement and McNemar's test for disagreement.

RESULTS

11 of 28 psittaciforms (39.3 per cent) had clinical signs considered specific for liver disease. 25 of 28 (89.3 per cent) psittaciforms had histopathological liver lesions. Gross changes radiographically and endoscopically agreed with histopathology in 57.1 per cent and 53.6 per cent of cases, respectively. Aspartate aminotransferase (AST) (48.1 per cent), creatine phosphokinase (73.1 per cent) and albumin by protein electrophoresis (50 per cent) showed the highest agreement. Kappa was not significant for any parameters, while McNemar's test for disagreement was significant for radiography, endoscopy, AST, lactate dehydrogenase, bile acid, total protein (chemistry), cholesterol, triglycerides, uric acid and glucose.

CONCLUSION

Overall, changes on plasma biochemistry, radiography or endoscopy are non-specific and do not consistently agree with histopathology results. Endoscopic liver biopsy is highly recommended if there is clinical suspicion of hepatic disease.

Functional and Anatomic Correlates of Neural Aging in Birds

Avian species show variation in longevity, habitat, physiologic characteristics, and lifetime endocrine patterns. Lifetime reproductive and metabolic function vary. Much is known about the neurobiology of the song system in many altricial birds. Little is known about aging in neural systems in birds. Captive birds often survive beyond the age they would in the wild, providing an opportunity to gain an understanding of the physiologic and neural changes. This paper reviews the available information with the goal of capturing areas of potential investigation into gaps in our understanding of neural aging as reflected in physiologic, endocrine, and cognitive aging.

Avian Oncology: Diseases, Diagnostics, and Therapeutics

Companion birds are increasingly living longer due to improved husbandry, nutrition, and veterinary care. As a consequence, a growing number of geriatric disease conditions are diagnosed and managed by veterinarians. Awareness of bird owners of diagnostic and treatment options for neoplastic diseases in humans and domestic animals has led to increasing demand to provide advanced diagnostic and treatment modalities for companion birds diagnosed with neoplasia. Treatment remains challenging in many companion birds due to the lack of information regarding prognosis and efficacy of antineoplastic treatments in these species. There is no established standard of care for most tumors in companion birds.

Systemic Clinical and Metabolic Diseases

Like other animals pet and companion birds are also prone to systemic illness. This is presented in the form of certain clinical signs and symptoms which is known as “ sick-bird syndrome.”

EVALUATION OF POTENTIAL RISK FACTORS ASSOCIATED WITH CATARACT IN CAPTIVE MACARONI (EUDYPTES CHRYSOLOPHUS) AND ROCKHOPPER PENGUINS (EUDYPTES CHRYSOCOME)

Complete ophthalmic examinations were performed on 160 Macaroni penguins ( Eudyptes chrysolophus ) and 90 Rockhopper penguins ( Eudyptes chrysocome ) at eight North American zoological institutions. Cataract prevalence in the Macaroni population was 46.5% (n = 74) of penguins and 42.3% (135/319) of eyes. Cataract prevalence in the Rockhopper population was 45.5% (n = 40) of penguins and 40.6% (73/180) of eyes. The mean age of Macaroni penguins without ocular disease was 7.4 ± 5.8 yr, while that of Rockhoppers was 9.8 ± 6.4 yr. Risk factors for cataract were examined through husbandry surveys completed by each institution and by evaluation of light intensity and ultraviolet (UV) light measurements acquired in each penguin exhibit. Risk factors associated with cataract in Macaroni penguins included age, dietary smelt, hand-feeding, and fluorescent exhibit lighting. Risk factors associated with cataract in Rockhopper penguins included age, dietary capelin, increasing population density, and increasing length of minimum photoperiod. Factors associated with decreased odds of cataract in Macaroni penguins included saltwater pool, monitoring of water quality for salinity, pH, and alkalinity; use of water additives; presence of pool filtration and sterilization systems; use of metal halide lightbulbs; increasing light intensity; and UV spectrum lighting. Factors associated with decreased odds of cataract in Rockhoppers included dietary herring and krill, increasing exhibit land area, pool temperature monitoring, increasing maximum photoperiod, and increasing minimum UV light.

Ocular findings and reference values for selected ophthalmic diagnostic tests in the macaroni penguin (Eudyptes chrysolophus) and southern rockhopper penguin (Eudyptes chrysocome)

OBJECTIVE

To describe ophthalmic examination findings and standard diagnostic test results in 2 penguin species.

ANIMALS STUDIED

Macaroni & Southern Rockhopper Penguins.

PROCEDURE

Complete ophthalmic examinations including Schirmer tear test (STT), modified phenol red thread test (PTT), tonometry, and echobiometry were performed on penguins housed at the Detroit Zoo. Mean and standard deviation of ophthalmic tests are reported and compared for significance using two sample t-tests with significance set at P < 0.05. Correlations between variables were assessed using Pearson's correlation coefficient.

RESULTS

Cataracts were the most common finding, present in 64% of Macaroni Penguins, and 68% of Rockhopper Penguins. There were anterior segment anomalies in all eyes with cataracts consistent with lens-induced uveitis. The mean modified PTT for the Macaronis was 24.7 ± 6.37 mm/15 s and 25.1 ± 7.07 mm/15 s in the Rockhoppers. The mean STT value for the Macaronis was 12.1 ± 5.43 mm/min and 11.0 ± 3.96 mm/min in the Rockhoppers. Mean intraocular pressure (IOP) for the Macaronis was 21.9 ± 7.05 mmHg measured by applanation tonometry and 29.1 ± 7.16 mmHg using rebound tonometry. The Rockhoppers had a mean IOP of 20.0 ± 5.77 mmHg and 24.1 ± 5.09 mmHg for applanation and rebound tonometry, respectively. In both populations, there was a significant difference in IOP measurement between the two instruments. In the Macaroni penguins, the presence of cataracts correlated significantly with increased age and lower IOP readings. Anterior chamber distance and axial globe length were significantly greater in males than in females in both penguin species.