The avian iris is mainly composed of striated muscle fibers, and the topical parasympatholytic drugs used in mammals to induce pupil dilation are ineffective in birds. The achievement of mydriasis in conscious birds is only possible by using neuromuscular blocking agents such as curariform drugs. To determine the efficacy of the neuromuscular blocking agent rocuronium bromide as a mydriatic agent in European kestrels (Falco tinnunculus) and to assess possible adverse effects due to its use, 10 kestrels received a single topical instillation with a pipette of 0.12 mg of rocuronium in each eye (total dose, 0.24 mg/bird). Pupil diameter was measured with a pupillary gauge, and pupillary light reflex was assessed by using a standard light source from time zero (Tbase) to 250 minutes after application (T250). Baseline pupil size (Tbase) was 3.30 (0.71) mm in both eyes. Maximal mydriasis was achieved at T90 minutes with a mean (SD) pupillary diameter of 6.30 (0.42) mm and 6.35 (0.41) mm in the right eye and left eye, respectively. At the dose used, rocuronium bromide induced a consistent bilateral simultaneous mydriasis without noticeable adverse effects, and it can be considered a reliable and safe topical mydriatic agent in kestrels.

Marbofloxacin, a fluoroquinolone developed specifically for veterinary use, has demonstrated considerable pharmokinetic variation among avian species. The goal of this study was to determine the disposition kinetics of marbofloxacin in mallard ducks (Anas platyrhynchos) after a single intravenous injection. Six wild mallard ducks were used in the study. Marbofloxacin was injected at a dose of 2 mg/kg into the basilic vein, and blood was subsequently collected at regular intervals from each bird. Plasma marbofloxacin concentrations were determined by using high-performance liquid chromatography. The volume of distribution at steady state was 1.78 ± 0.37 L/kg, and the total plasma clearance was 0.59 ± 0.08 L/kg per hour. Marbofloxacin had a relatively short permanence, with a elimination half-life of 2.81 ± 1.20 hours, a terminal half-life of 2.43 ± 0.61 hours, and a mean residence time of 2.99 ± 0.52 hour. The maximum observed concentration (C_max) and area under the curve (AUC) were 1.34 ± 0.27 µg/mL and 3.75 ± 0.56 µg · h/mL, respectively. Values of minimum inhibitory concentration (MIC), C_max, and AUC have been used to predict the clinical efficacy of a drug in treating bacterial infections, with a C_max ∶ MIC value of 10 and an AUC ∶ MIC ratio of 125–250 associated with optimal bactericidal effects. By using the study data and MIC breakpoints of 0.125 µg/mL or 0.2 µg/mL, values derived for C_max ∶ MIC were 9.37 ± 0.99 and 5.85 ± 0.62, respectively, and for AUC ∶ MIC were 29.99 ± 4.51 and 18.74 ± 2.82, respectively. By using MIC values of 0.125 and 0.2 µg/mL and a target AUC ∶ MIC  =  125, the calculated optimal daily marbofloxacin dosages for mallard ducks were 9.24 and 14.78 mg/kg, respectively. These results suggest that, primarily because of the high total plasma clearance observed, the marbofloxacin dose for treatment of bacterial diseases in mallard ducks should be increased after intravenous administration. Intravenous doses of 10–15 mg/kg should be assessed by studying their potential toxicity and efficacy in sick birds.

An adult female African collared dove (Streptopelia roseogrisea) was presented for examination of a mass on the medial surface of the left wing. The mass had been present for 2 months but had grown rapidly over the previous 2 weeks. One week after presentation, the mass was surgically excised and the involved alular bone was removed. Results of histologic examination of the mass were consistent with an aneurysmal bone cyst. No underlying factor could be found in this case. The wound healing was uneventful, and no mass recurrence was observed during the following year. To our knowledge, this is the first report of an aneurysmal bone cyst in a columbiform bird.

Hypocalcemic-induced seizure activity is a clinical entity that is commonly diagnosed in neurologic African grey parrots (Psittacus erithacus). Plasma calcium levels are typically less than 6.0 mg/dL at the time of seizure activity, and although the underlying cause of the hypocalcemia has not yet been determined, many theories have been proposed. An African grey parrot that had been fed a seed diet for 8 years was presented with hypocalcemia and seizures and exhibited precipitously declining plasma calcium levels, despite aggressive calcium and vitamin A, D, and E supplementation for 4 days. Baseline magnesium levels in this parrot were determined to be 1.9 mg/dL; therefore, magnesium sulfate was administered at a dose of 20 mg/kg IM once. Twenty-four hours after supplementation, the plasma magnesium level was 3.3 mg/dL, and no further seizure activity was observed. We believe that a primary dietary magnesium deficiency may have been present in this African grey parrot, similar to a syndrome in leghorn chicks, which is frequently characterized by progressive hypocalcemia that is unable to be corrected by calcium supplementation alone.

A 3-year-old male, hybrid mallard duck (Anas platyrhynchos) was presented with a 2-year history of progressive, ascending paresis and paralysis. On presentation, the bird was in sternal recumbency and displayed intermittent focal seizures and intention tremors. Proprioceptive deficits and absent withdrawal reflexes were observed in both pelvic limbs, wing extension was limited, and reflexes were diminished bilaterally. Other findings included emaciation and dehydration. Results of a complete blood count and plasma biochemical analysis revealed anemia, hypoproteinemia, hypoglycemia, and hyperuricemia. Radiographs were unremarkable and results of an Aspergillus antibody were weakly positive. The duck went into cardiopulmonary arrest and died approximately 1 hour after initiating treatment with intravenous crystalloid fluids. A postmortem diagnosis of neuronal ceroid lipofuscinosis (NCL) was made based on the presence of neuronal granular cytoplasmic material that was autofluorescent and stained with periodic acid–Schiff and Luxol fast blue. To our knowledge, this is only the second case report of NCL in an avian species and the first in waterfowl.

A 12-year-old female black-masked lovebird (Agapornis personata) with a cobalt color mutation was presented for self-mutilation of a mass located on the right lateral neck. Cytologic evaluation of the soft tissue mass revealed a predominance of poorly stained mast cells with metachromatic intracytoplasmic granules. The presumptive diagnosis was cutaneous mast cell tumor. Clinical evaluation, results of a complete blood cell count and biochemical analysis, and radiographs did not reveal systemic manifestation of mast cell disease. The mass was surgically resected, but surgical margins were limited because of the location of the mass and the small size of the patient. The lovebird died the day after surgery. Gross postmortem examination revealed splenomegaly, multifocal pinpoint white nodules throughout the liver parenchyma, severe thickening and yellow coloration of the great vessels, and pale pink swelling of the caudal right kidney. Histopathologic analysis of the resected mass revealed sheets of round cells that contain metachromatic granules, defined as neoplastic mast cells, within a fine fibrovascular stroma. Similar neoplastic cells were seen in the right kidney, hepatic sinusoids, splenic pulp, periovarian connective tissue, and bone marrow. The histopathologic diagnosis was a cutaneous mast cell tumor and disseminated mast cell disease, or mastocytosis. To the authors' knowledge, this is the first reported case of a cutaneous mast cell tumor and mastocytosis in a psittacine bird.

An adult channel-billed toucan (Ramphastos vitellinus), imported from Surinam, South America, 18 months earlier, was found dead in its cage. At necropsy, the hock joints were swollen bilaterally and had a reduced range of motion. Small curled worms were present in subcutaneous tissue around the joints, with edema and fibrin formation. These worms were classified as the filarioid nematode, Pelecitus species. Blood-borne microfilariae were seen in cytologic impression smears of the lung and the leg lesions.