Hugues Beaufrère

Prevalence of and risk factors associated with atherosclerosis in psittacine birds.

OBJECTIVE To estimate the prevalence of clinically relevant atherosclerotic lesions in birds and identify epidemiological variables and illness types associated with development of atherosclerosis. DESIGN Retrospective case-control study. SAMPLE Records of 7683 psittacine birds, including 525 with advanced atherosclerosis. PROCEDURES 5 pathology centers provided databases and access to histopathology slides. Age and sex were collected for all birds of the Amazona, Ara, Cacatua, Nymphicus, and Psittacus genera. Databases were searched for atherosclerosis cases, and slides were reviewed for the presence of type IV through VI atherosclerotic lesions. Results were used to build several multiple logistic models to define the association between advanced atherosclerosis and age, sex, genus, illness type, and specific lesions. Prevalence was reported as a function of age, sex, and genus. RESULTS In the first model including 7683 birds, age, female sex, and the genera Psittacus, Amazona, and Nymphicus were significantly associated with clinically relevant atherosclerosis detected via necropsy. Subsequent models of 1,050 cases revealed further associations with reproductive disease, hepatic disease, and myocardial fibrosis, controlling for age, sex, and genus. CONCLUSIONS AND CLINICAL RELEVANCE Age, female sex, and 3 genera appeared to be positively associated with the presence of advanced atherosclerotic lesions in psittacine birds. This information may be useful in clinical assessment of the cardiovascular system and patient management. Reproductive diseases were the only potentially modifiable risk factor identified and could be a target for prevention in captive psittacine birds.

Avian Vascular Imaging: A Review

Abstract Vascular diseases in birds are not uncommon, according to findings from postmortem surveys. Although atherosclerosis affecting psittacine birds appears overrepresented, some degenerative, infectious, neoplastic, and congenital vascular diseases may also occur. A variety of imaging diagnostic tools may be used to evaluate the avian vascular system, such as conventional radiography, fluoroscopy, rigid endoscopy, computed tomography, angiography, transcoelomic, and transesophageal ultrasound examination. The wide array of current diagnostic imaging tools offers the clinician capabilities to investigate avian cardiovascular abnormalities. Further research in this domain and constant efforts to apply several, and newer, vascular imaging modalities in clinical cases are needed to expand our avian cardiovascular knowledge base. The ability to diagnose vascular pathologic processes in small avian patients may be improved by recent developments in diagnostic imaging technology.

Characterization and classification of psittacine atherosclerotic lesions by histopathology, digital image analysis, transmission and scanning electron microscopy

Atherosclerosis is a degenerative and inflammatory vascular disease characterized in mammals and birds by the accumulation of inflammatory cells, lipids, calcium, and formation of large fibrofatty lesions within the intima of arteries resulting in the disorganization of the arterial wall and stenosis of the lumen. Despite the high incidence of atherosclerosis in parrots and the high number of case reports, there are few pathologic investigations and the ultrastructural study of the lesions has not been documented. Sixty-three major arteries were collected from 24 psittacine birds of 11 species during routine post-mortem examinations. Samples from the major arteries were fixed in 2% paraformaldehyde and 1.25% glutaraldehyde, and processed for transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Additional samples were fixed in 10% formalin and embedded in paraffin for histological examination. Additional histochemical stains for calcium, elastic fibres, and lipid were performed. Toluidine blue-stained 0.5 µm-thick resin sections were also obtained. Digital image analysis was performed to provide objective quantitative information on the different lesions. The histopathology and ultrastructure of psittacine atherosclerosis were found to be similar to other avian and mammalian species. Seven lesion types could be described, which were similar to the human classification system. Digital image analysis, TEM, and SEM helped to further describe the lesions and refine the classification system. TEM findings were similar to other avian and mammalian species with the notable presence of macrophage-derived and smooth muscle cell-derived foam cells and extracellular lipid. SEM revealed various stages of endothelial surface defects and, occasionally, adherent blood cells.

Intraocular Pressure in Captive Black-footed Penguins (Spheniscus demersus) Measured by Rebound Tonometry

Abstract Intraocular pressure (IOP) measurement is a common procedure during eye examinations in birds. Differences in the IOP between avian species have been reported, which suggests the need to establish species-specific reference ranges. To determine IOP values of captive black-footed penguins (Spheniscus demersus), we obtained IOP readings with the use of a rebound tonometer by using two established calibration settings (dog and horse). No difference was seen in the IOP between the left and right eye when the horse setting was used; however, a difference was present when using the dog setting. No significant difference between the IOP of male and female penguins was seen in both eyes when the dog or horse setting was used. Rebound tonometry appears to be a safe and repeatable method to obtain IOP values in black-footed penguins.

Experimental Diet-Induced Atherosclerosis in Quaker Parrots (Myiopsitta monachus)

Spontaneous atherosclerosis is common in psittaciformes, and clinical signs associated with flow-limiting stenosis are encountered in pet birds. Nevertheless, a psittacine model of atherosclerosis has not been developed for research investigations. Sixteen captive-bred Quaker parrots (Myiopsitta monachus) were used in this study. While 4 control birds were fed a maintenance diet, 12 other birds were fed an atherogenic diet composed of 1% cholesterol controlling for a calorie-to-protein ratio for periods ranging from 2 to 8 months. The birds were euthanized at the end of their respective food trial period. Histopathology, transmission electron microscopy, and cholesterol measurement were performed on the ascending aorta and brachiocephalic and pulmonary arteries. Plasma lipoproteins, cholesterol, and triglycerides were also measured on a monthly basis. Significant atherosclerotic lesions were induced within 2 months and advanced atherosclerotic lesions within 4 to 6 months. The advanced lesions were histologically similar to naturally occurring lesions identified in the same parrot species with a lipid core and a fibrous cap. Ultrastructurally, there were extracellular lipid, foam cell, and endothelial changes. Arterial cholesterol content increased linearly over time. Plasma cholesterol and low-density lipoprotein (LDL) significantly increased over time by an average of 5- and 15-fold, respectively, with a shift from high-density lipoprotein to LDL as the main plasma lipoprotein. Quaker parrots also exhibited high plasma cholesteryl ester transfer protein activity that increased, although not significantly, over time. This experiment demonstrates that in Quaker parrots fed 1% cholesterol, advanced atherosclerosis can be induced relatively quickly, and lesions resemble those found in other avian models and humans.

Diagnosis of presumed acute ischemic stroke and associated seizure management in a Congo African grey parrot

CASE DESCRIPTION A 14-year-old Congo African grey parrot (Psittacus erithacus erithacus) was evaluated for an acute onset of falling off of its perch and tonic-clonic movements. CLINICAL FINDINGS Clinical signs were consistent with partial seizures. Findings on whole-body radiography, CBC, and plasma biochemical analysis were unremarkable. Plasma magnesium, ionized calcium, and bile acids concentrations were within reference limits. A magnetic resonance imaging (MRI) examination of the head revealed the presence of a focal hyperintensity at the central to left side of the optic chiasm and a hyperintense focus in the right side of the midbrain area in T2-weighted and FLAIR pulse sequence images. These findings were most consistent with an acute ischemic stroke with 2 brain infarcts. TREATMENT AND OUTCOME Seizures were initially managed with potassium bromide and phenobarbital administration. On the basis of poor results and difficulties to reach therapeutic blood concentrations, the treatment plan was changed to levetiracetam and zonisamide administration. Blood concentrations were monitored for both drugs, and the frequency of seizures substantially decreased thereafter. A follow-up MRI examination 2 months later revealed resolution of the hyperintense signals. During the 20-month follow-up period, subsequent clusters of seizures were managed by adjusting levetiracetam and zonisamide dosages and adding clonazepam and gabapentin administration to the treatment plan. Regression of intraparenchymal hyperintense lesions and improvement of clinical signs made a diagnosis of acute ischemic stroke most likely. CLINICAL RELEVANCE Findings for this Congo African grey parrot indicated that an antemortem diagnosis of an acute ischemic stroke followed by long-term seizure management may be possible in affected psittacines.

Feasibility of transesophageal echocardiography in birds without cardiac disease

OBJECTIVE To establish a technique of transesophageal echocardiography (TEE) in birds without cardiac disease and describe the imaging planes obtained. DESIGN Validation study. ANIMALS 18 birds including 3 pigeons (Columbia livia), 3 barred owls (Strix varia), 2 red-tailed hawks (Buteo jamaicensis), 1 goose (Anser anser), 1 mallard duck (Anas platyrhynchos), 1 Muscovy duck (Cairina moschata), 2 brown pelicans (Pelecanus occidentalis), 2 Hispaniolan Amazon parrots (Amazona ventralis), 2 red-fronted macaws (Ara rubrogenys), and 1 military macaw (Ara militaris). PROCEDURES For each bird, anesthesia was induced and maintained by use of isoflurane. A pediatric, multiplane transesophageal ultrasound probe was passed into the esophagus and adjusted to the level of the heart for echocardiography. Probe positions were recorded via fluoroscopy, and associated imaging planes were described. RESULTS TEE was performed successfully in all birds except the pelicans, 1 Hispaniolan Amazon parrot, and the red-fronted macaws. Five imaging planes of the heart were consistently viewed from 3 positions of the probe (identified as caudal, middle, and cranial positions relative to the cardiac silhouette). M-mode echocardiography of the left ventricle and the aortic root was performed. Color flow and spectral Doppler ultrasonographic images of in- and outflow regions were obtained. One Hispaniolan Amazon parrot died as a result of esophageal perforation. CONCLUSIONS AND CLINICAL RELEVANCE TEE examination of birds was feasible and provided a larger number of imaging planes with better resolution and details than those typically achieved via a transcoelomic approach. However, TEE should be performed with caution in psittacines.

Evaluation of thermal antinociceptive effects after intramuscular administration of buprenorphine hydrochloride to American kestrels (Falco sparverius)

OBJECTIVE To evaluate the thermal antinociceptive effects and duration of action of buprenorphine hydrochloride after IM administration to American kestrels (Falco sparverius). ANIMALS 12 healthy 3-year-old American kestrels. PROCEDURES Buprenorphine hydrochloride (0.1, 0.3, and 0.6 mg/kg) and a control treatment (saline [0.9% NaCl] solution) were administered IM in a randomized crossover experimental design. Foot withdrawal response to a thermal stimulus was determined 1 hour before (baseline) and 1.5, 3, and 6 hours after treatment administration. Agitation-sedation scores were determined 3 to 5 minutes before each thermal stimulus. Adverse effects were monitored for 6 hours after treatment administration. RESULTS Buprenorphine hydrochloride at 0.1, 0.3, and 0.6 mg/kg, IM, increased thermal threshold for 6 hours, compared with the response for the control treatment. There were no significant differences among buprenorphine treatments. A mild sedative effect was detected at a dose of 0.6 mg of buprenorphine/kg. CONCLUSION AND CLINICAL RELEVANCE At the doses tested, buprenorphine hydrochloride resulted in thermal antinociception in American kestrels for at least 6 hours, which suggested that buprenorphine has analgesic effects in this species. Further studies with longer evaluation periods and additional forms of noxious stimuli, formulations, dosages, and routes of administration are needed to fully evaluate the analgesic effects of buprenorphine in American kestrels.

Long-term Management of Ovarian Neoplasia in Two Cockatiels (Nymphicus hollandicus)

Abstract: Cockatiels (Nymphicus hollandicus) are commonly diagnosed with ovarian neoplasia. However, there is very little information regarding medical management of this disease condition and subsequent patient response. Long-term medical therapy of 2 cockatiels eventually diagnosed with ovarian neoplasia is described along with responses to the treatment regimens. Each bird had initial signs consistent with reproductive disease (chronic egg laying, ascites, and lethargy) and respiratory distress. The diagnosis of ovarian adenocarcinoma was confirmed on postmortem examination of both birds. The birds were conservatively managed by periodic coelomocentesis and gonadotropin-releasing hormone (GnRH) agonist administration for 9 and 25 months, respectively. A positive response to GnRH agonist therapy was documented in 1 of the 2 birds. These 2 cases demonstrate that periodic coelomocentesis with or without GnRH agonist therapy may be a viable option for the long-term management of ovarian neoplasia and reproductive-organ–associated ascites in cockatiels.

Intermittent Claudication-like Syndrome Secondary to Atherosclerosis in a Yellow-naped Amazon Parrot (Amazona ochrocephala auropalliata)

Abstract A 25-year-old yellow-naped Amazon parrot (Amazona ochrocephala auropalliata) was presented for nasal discharge and sneezing. Physical examination revealed poor feather quality, a mild serous nasal discharge, and a mass on the dorsal surface of the oral cavity. Cytologic examination of a mass aspirate as well as results of a choanal culture revealed squamous metaplasia of the salivary glands and bacterial rhinitis, respectively. Following resolution of the presenting conditions, the patient was presented for hind limb weakness and ataxia. The clinical signs were transient and generally resolved with rest but could be reproduced after stressful episodes, such as restraint for procedures or treatment. Test results from a complete blood count, biochemistry profile, whole-body radiographs, needle electromyography of the leg muscles, and an edrophonium challenge test were within reference limits. Based on the clinical signs and results of the diagnostic workup, the presumptive diagnosis was intermittent claudication, a condition caused by peripheral vascular disease and defined as intermittent weakness and pain in the legs induced by exercise and relieved by rest. Shortly after initiation of treatment with isoxsuprine, the bird died. Postmortem examination and histopathology revealed severe atherosclerotic lesions throughout the vascular system with stenotic lesions present in the abdominal aorta and femoral arteries. Electron microscopic examination of the great arteries was also performed and helped to further characterize the nature of the lesions. This case is the first report, to our knowledge, of an intermittent claudication-like syndrome associated with peripheral atherosclerosis in a psittacine bird. In addition, the distribution and some of the macroscopic and histopathologic features of the lesions differ from previous descriptions of atherosclerosis in psittacine birds.