Ricardo de Matos

Calcium metabolism in birds.

Calcium is one of the most important plasma constituents in mammals and birds. It provides structural strength and support (bones and eggshell) and plays vital roles in many of the biochemical reactions in the body. The control of calcium metabolism in birds is highly efficient and closely regulated in a number of tissues, primarily parathyroid gland, intestine, kidney, and bone. The hormones with the greatest involvement in calcium regulation in birds are parathyroid hormone, 1,25-dihydroxyvitamin D(3) (calcitriol), and estrogen, with calcitonin playing a minor and uncertain role. The special characteristics of calcium metabolism in birds, mainly associated with egg production, are discussed, along with common clinical disorders secondary to derangements in calcium homeostasis.

Adrenal Steroid Metabolism in Birds: Anatomy, Physiology, and Clinical Considerations

The hypothalamo-pituitary-adrenal system in birds is anatomically and functionally different from that in mammals. The adrenal gland structure and corticosteroid hormone physiology of birds will be reviewed. The anatomy and physiology sections of this article will be important for better understanding the pathogenesis, diagnosis, and possible treatment of primary or secondary adrenal gland disease. Causes of hyper- and hypoadrenocorticism in birds also will be reviewed. The article will conclude with current indications and complications to the clinical use of glucocorticoids in birds.

Postintubation tracheal stenosis in a blue and gold macaw (Ara ararauna) resolved with tracheal resection and anastomosis

Abstract A 20-year-old female blue and gold macaw (Ara ararauna) was presented with an acute onset of labored breathing and vocalization changes. Tracheoscopy revealed a stenotic tracheal lesion, which reduced the luminal diameter by approximately 75%. Tracheal resection and anastomosis was performed, and the tracheal lesion was submitted for histopathologic analysis. Postoperative therapy included antibiotic, antifungal, and anti-inflammatory medications. The trachea healed with no major complications. The histologic diagnosis was mild, focal, chronic tracheitis. The cause of the lesion was presumed to be postintubation stenosis on the basis of the normal gross appearance of the external trachea, the location of the lesion, and a recent history of general anesthesia delivered by endotracheal tube.

Nasal Adenocarcinoma and Secondary Chronic Sinusitis in a Hyacinth Macaw (Anodorhynchus hyacinthinus)

Abstract An adult male hyacinth macaw (Anodorhynchus hyacinthinus) that presented for acute onset nasal discharge and dyspnea had purulent discharge from the right naris and serosanguineous discharge from the left naris on physical examination. Results of a complete blood count revealed severe leukocytosis with a mature heterophilia. Computed tomography scans showed a large amount of soft-tissue attenuating material within the infraorbital sinus and associated diverticula. Aerobic culture results of the nasal discharge showed a mixed population of Staphylococcus intermedius and Pasteurella species, including Pasteurella pneumotropica; all isolated bacteria were susceptible to enrofloxacin. Clinical signs did not resolve over the course of 9 weeks of antibiotic treatment. The macaw died after cardiopulmonary arrest while hospitalized. At necropsy, a 2 × 2 × 3–cm firm, tan, friable, space-occupying mass surrounded by a thick exudate was present in the left preorbital diverticulum of the infraorbital sinus. The cranioventral one-third of the trachea contained a 4 × 0.5–cm white-yellow plaque. On histologic examination, the sinus mass was diagnosed as a nasal adenocarcinoma, and the tracheal plaque was caused by fungal infection, most likely with an Aspergillus species.

Computed tomographic features of clinical and subclinical middle ear disease in domestic rabbits (Oryctolagus cuniculus): 88 cases (2007–2014)

OBJECTIVE To describe and compare CT abnormalities of the middle ear in rabbits (Oryctolagus cuniculus) that had clinical or subclinical middle ear disease and to determine the prevalence of otitis media and evaluate the role of predisposing factors for otitis media in that species. DESIGN Retrospective case series. ANIMALS 88 domestic rabbits. PROCEDURES Medical records for rabbits that underwent CT of the head in June 2007 through February 2014 were searched and classified on the basis of reason for head CT (i.e., ear-related disease vs non-ear-related disease). The ears, upper respiratory tract, teeth, and other important structures of each rabbits head were evaluated. Follow-up information was obtained for rabbits with CT abnormalities of the middle ear without clinical signs (i.e., subclinical disease). RESULTS 12 of 21 (57%) rabbits with clinical signs of ear disease and 18 of 67 (27%) rabbits without clinical signs of ear disease had CT abnormalities of the middle ear. In CT images, all affected ears had soft tissue-attenuating material within the tympanic bulla. Tympanic bulla lysis was associated with clinical middle ear disease. Most (12/18) rabbits with subclinical middle ear disease remained subclinical after CT examination. Middle ear CT-detected changes and lop-ear conformation or otitis externa were strongly correlated; middle ear disease and upper respiratory tract disease were not correlated. CONCLUSIONS AND CLINICAL RELEVANCE Data suggested that subclinical otitis media frequently affects rabbits, and those with bulla lysis should be closely monitored. Lop-eared rabbits and rabbits with otitis externa had a higher risk of developing otitis media.

Chinese Box turtle (Cuora flavomarginata) with lymphoid leukemia characterized by immunohistochemical and cytochemical phenotyping.

Lymphoid leukemia of T-cell origin was diagnosed in a male Chinese Box turtle, Cuora flavomarginata, of approximately 25 years of age. The turtle presented with a history of anorexia, open-mouth breathing, and lethargy for one week. The CBC findings included a mildly increased PCV, and severe leukocytosis due to high numbers of atypical cells interpreted to be blasts. The blasts were medium-sized cells with round to pleomorphic nuclei, slightly clumped chromatin, indistinct nucleoli, and scant moderate-to-dark blue cytoplasm with occasional red-to-purple cytoplasmic granulation. Cytochemical and immunohistochemical staining indicated that the neoplastic cells were positive for CD3 and α-naphthyl butyrate esterase (ANBE), leading to the diagnosis of T-cell lymphoid leukemia. Histology of tissues collected at necropsy showed multifocal infiltrations of neoplastic round cells in the liver, spleen, kidneys, testicles, pancreas, thyroid, duodenum, bone marrow, epicardium, and myocardium. Transmission electron microscopy failed to identify viral particles within the neoplastic cells. This article describes the hematologic, histologic, and ultrastructural abnormalities associated with lymphoid leukemia in this turtle, and advanced diagnostic methods used for phenotyping the T-cell origin.

Phacoemulsification of bilateral mature cataracts in a Texas rat snake (Elaphe obsoleta lindheimeri)

CASE DESCRIPTION A 10-year-old sexually intact male client-owned Texas rat snake (Elaphe obsoleta lindheimeri) was referred for evaluation because of a 5-month history of progressive bilateral ocular opacities and abnormal behavior. CLINICAL FINDINGS On ophthalmic examination, the snake had bilateral mature cataracts and uveal cysts. No additional ophthalmic or physical abnormalities were detected. Results of CBC, serum biochemical analysis, and ocular ultrasonography were unremarkable. TREATMENT AND OUTCOME Bilateral spectaculotomy was performed, followed by bilateral phacoemulsification and uveal cyst aspiration, without complication. Histologic evaluation of the phacoemulsified lens material revealed only nonspecific findings associated with cataractogenesis. Vision was restored and the abnormal behaviors resolved after cataract surgery. Long-term follow-up examination performed 60 weeks after surgery revealed no additional ocular or physical abnormalities. CLINICAL RELEVANCE The ocular anatomic and physiologic characteristics of snakes can pose intraoperative and postoperative challenges to phacoemulsification, but the outcome achieved for this surgical case suggested that successful cataract surgery is possible in these species. This case further demonstrated that cataracts may be associated with reversible behavioral abnormalities in captive snakes.

Bone marrow cell composition and morphology in healthy juvenile female New Zealand White rabbits (Oryctolagus cuniculus)

OBJECTIVE To provide contemporary preliminary guidelines for the morphological evaluation of bone marrow in conjunction with CBC results for healthy juvenile (3- to 6-month-old) female New Zealand White rabbits (Oryctolagus cuniculus). ANIMALS 22 female New Zealand White rabbits. PROCEDURES Each rabbit was sedated, and a blood sample (3 mL) was collected from an ear artery for a CBC, after which the rabbit was euthanized. Within 5 minutes after euthanasia, bone marrow samples were obtained from the femur for cytologic and histologic evaluation. Bone marrow specimens for cytologic evaluation were stained with modified Wright stain, and those for histologic evaluation were stained with either H&E or Prussian blue stain. RESULTS The CBC results were within published reference ranges for all rabbits except 4, each of which had mild leukopenia. Cytologic assessment of bone marrow revealed a median myeloid-to-erythroid ratio of 0.7 and 2.8 megakaryocytes/low-power field (magnification, 100X), and the median percentages of lymphocytes, plasma cells, and macrophages were 11.5%, 0.1%, and 0%, respectively. The myeloid-to-erythroid ratio was not significantly correlated with any CBC variable. On histologic evaluation of bone marrow, the cellularity ranged from 30% to 50%, there were 2.1 to 7.7 megakaryocytes/hpf (magnification, 400X), and no iron stores were visible in H&E or Prussian blue-stained specimens. CONCLUSIONS AND CLINICAL RELEVANCE Results of the present study provided contemporary preliminary guidelines for the evaluation of bone marrow in healthy laboratory rabbits.

Phacoemulsification of bilateral cataracts in two pet rabbits

Two 3 year-old, healthy, client-owned Lop rabbits presented with bilateral cataracts. After performing a physical examination, bloodwork, ocular ultrasonography and electroretinography, both animals were deemed good surgical candidates for phacoemulsification. Bilateral cataract surgery was performed and both rabbits regained vision in both eyes. Both animals developed post-operative ocular hypertension and one animal developed corneal ulcers immediately after surgery. Both surgical complications resolved with medical management. This case series describes phacoemulsification of bilateral cataracts in 2 companion rabbits and the use of an intraocular lens in 1 rabbit. Surgical treatment of cataracts can be considered as a treatment option whenever a healthy rabbit is visually impaired due to cataracts.

Spontaneous fatal Human herpesvirus 1 encephalitis in two domestic rabbits (Oryctolagus cuniculus)

Despite the particular susceptibility of the rabbit to experimental infection with Human herpesvirus 1 (HHV-1) and the high seroprevalence of HHV-1 in human beings, reports of natural infection in pet rabbits are rare. The current report describes 2 cases of HHV encephalitis in pet rabbits in North America. Antemortem clinical signs included seizures, ptyalism, and muscle tremors. Results of complete blood cell count and plasma biochemistry panel were unremarkable except for a mild leukocytosis in both cases. Both rabbits died after a short period of hospitalization. Rabbit 1 presented mild optic chiasm hemorrhage on gross examination, while rabbit 2 had no gross lesions. Histologic findings for both cases included lymphocytic and/or lymphoplasmacytic encephalitis with necrosis and the presence of intranuclear inclusion bodies in neurons and glial cells. Polymerase chain reaction (PCR) analysis of affected brain tissue using primers specific for Human herpesvirus 1 and 2 confirmed diagnosis of HHV encephalitis for rabbit 1. Immunohistochemical staining (poly- and monoclonal) and PCR analysis using primers specific to HHV-1 confirmed the diagnosis of HHV-1 encephalitis for rabbit 2. The owner of rabbit 2 was suspected to be the source of infection due to close contact during an episode of herpes labialis. Given the high susceptibility of rabbits to experimental HHV-1, high seroprevalence of HHV-1 in human beings, and severity of clinical disease in this species, clinician awareness and client education is important for disease prevention. Human herpesvirus 1 encephalitis should be considered as a differential diagnosis for rabbits with neurologic disease.