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Enrofloxacin is a fluoroquinolone antibiotic that is effective against many of the common gram-negative bacterial pathogens in raptors. This 3-period crossover study was designed to compare the pharmacokinetics of enrofloxacin after oral, intramuscular, or intravenous administration in red-tailed hawks (Buteo jamaicensis; n = 8) and great horned owls (Bubo virginianus; n = 5). In each study period, birds received a single dose of an injectable formulation of enrofloxacin (15 mg/kg) by 1 of these 3 routes. Oral administration was accomplished by force-feeding each bird a small freshly killed mouse that had received an intraperitoneal injection of enrofloxacin (in-prey). Intramuscular injections were divided into 2 sites in the pectoral musculature. Serial plasma samples were taken before administration and at 0.25, 0.5, 1, 2, 4, 8, 12, 24, and 48 hours after administration. Oral administration resulted in plasma concentrations of enrofloxacin that peaked at 4–8 hours in both species. Plasma concentrations remained at >1 μg/ml until at least 18 hours after administration, although an initial lag time of approximately 2–8 hours occurred for absorption from the gastrointestinal tract. Intramuscular administration resulted in plasma concentrations that peaked at 0.5–2 hours; enrofloxacin levels remained at >1 μg/ml for at least 15 hours. After intravenous administration to red-tailed hawks, enrofloxacin levels remained at >1 μg/ml for at least 15 hours. Two great horned owls showed acute weakness, bradycardia, and peripheral vasoconstriction during intravenous injection. These clinical signs resolved within 1–3 hours with supportive therapy; however, the intravenous route was not evaluated for the other 3 owls. We conclude that oral (in-prey) and intramuscular routes are reliable means of administration of injectable enrofloxacin in red-tailed hawks and great horned owls, using a dosage of 15 mg/kg q24h. Intravenous administration of enrofloxacin can be performed with caution in red-tailed hawks but should not be attempted in great horned owls.
Chronic and excessive egg laying is a frequent clinical syndrome in pet birds that can result in reproductive, nutritional, or behavioral pathology. Environmental manipulations to suppress ovarian activity are not always successful, and surgical intervention may involve serious risk. Tamoxifen, an estrogen blocker used to treat women with breast cancer, has been suggested as a chemical method of blocking the hen's reproductive cycle. In this study, 20 budgerigars (Melopsittacus undulatus) of various ages, presumed to be female but not actively laying eggs, were treated with tamoxifen for 38–46 weeks. Adverse effects analogous to those reported in humans were not observed; these included regurgitation, weight loss, loss of appetite, decreased activity, feather changes (alopecia), lameness or wing drooping (bone pain), abdominal distention, and radiographic changes in bone density. In budgerigars treated with tamoxifen, the packed cell volume, total serum calcium concentration, and total protein concentration remained relatively constant throughout the study. Leukopenia was the most significant adverse effect observed in treated birds. When treatment was discontinued, white blood cell counts returned to reference ranges in most birds. Antiestrogenic effects of tamoxifen were suggested by a change in cere color from white or brown to blue in birds during treatment. If tamoxifen is used in budgerigars, birds should be screened for subclinical infectious disease before treatment begins, and white blood cell counts should be monitored.
Ten psittacine birds (3 African grey parrots [Psittacus erithacus], 3 blue and gold macaws [Ara ararauna], 2 scarlet macaws [Ara macao], a harlequin macaw [Ara ararauna × macao], and a yellow-naped Amazon parrot [Amazona ochrocephala auropalliata]) with histories of chronic sinusitis were referred for evaluation before possible surgical therapy. The duration of clinical signs in these birds ranged from 8 months to 11 years, and response to conventional medical therapy had been poor. Diagnostic procedures performed in each bird included a physical examination, complete blood count, plasma biochemical analysis, survey whole body and skull radiographs, and skull magnetic resonance imaging. In 7 of the 10 birds, a discrete lesion was localized by using magnetic resonance imaging. Six of these 7 birds had surgery performed to remove the lesion. Four granulomas, a mucocele, and a polyp were diagnosed by histopathologic examination. The chronic sinusitis resolved after surgery in 5 birds. Magnetic resonance imaging proved to be an excellent diagnostic tool for examining the avian infraorbital sinus, allowing identification, localization, and characterization of lesions within the sinuses.
Gastrointestinal foreign bodies are reported in zoo birds, ratites, and juvenile psittacine birds; however, foreign body ingestion by adult psittacine birds is uncommon. We examined an adult umbrella cockatoo (Cacatua alba) because of a 4-month history of weight loss and intermittent, dark brown, malodorous stool. Physical examination findings were unremarkable. Results of laboratory testing revealed anemia, leukocytosis, lymphopenia, monocytosis, hypoproteinemia, and hypoalbuminemia; blood lead and zinc concentrations were not elevated. Enterococcus durans was cultured aerobically from the feces. Gas-filled, dilated intestinal loops and a gas-filled proventriculus were evident on survey radiographs. The clinical signs did not resolve with initial treatment, which included ciprofloxacin, ketoconazole, and a lactobacillus supplement. Over the next 2 months, results of blood tests revealed nonregenerative anemia, intermittent leukocytosis, monocytosis, and hypoproteinemia. Staphylococcus lugdunensis and E faecium were isolated from a crop swab and fecal samples. A barium contrast study revealed a filling defect in the area of the large intestine, whereas results of fluoroscopy were normal. The cockatoo responded poorly to further treatment, including 5 days of supportive care in the hospital, and the owners requested euthanasia. On necropsy, a string foreign body (7 cm long) was found in the proximal large intestine. The string had originated from a rope toy in the bird's cage.
An adult osprey (Pandion haliaetus) was evaluated because it was unable to fly and was experiencing severe respiratory distress. Despite supportive care, the bird died. Significant histopathologic findings included widespread, multifocal hemorrhage in parabronchi and air capillaries and emboli consisting of adipose connective tissue containing hematopoietic islands demonstrated in medium-sized pulmonary arteries. This is the first reported case of pulmonary fat embolism in a bird.
A 13-year-old female barred owl (Strix varia) presented for anorexia and lethargy. Physical examination revealed obesity, and radiographs demonstrated hepatomegaly. Plasma biochemistry values suggested liver disease, and hepatic lipidosis was confirmed by liver biopsy. Treatment included antibiotic and antifungal therapy, fluid administration, vitamin supplementation, and enteral alimentation with a balanced diet delivered through an esophagostomy tube. The owl completely recovered within 78 days after initial presentation.