Karen L. Rosenthal

Occlusive thrombi arise in mammals but not birds in response to arterial injury: evolutionary insight into human cardiovascular disease

Mammalian platelets are small, anuclear circulating cells that form tightly adherent, shear-resistant thrombi to prevent blood loss after vessel injury. Platelet thrombi that form in coronary and carotid arteries also underlie common vascular diseases such as myocardial infarction and stroke and are the target of drugs used to treat these diseases. Birds have high-pressure cardiovascular systems like mammals but generate nucleated thrombocytes rather than platelets. Here, we show that avian thrombocytes respond to many of the same activating stimuli as mammalian platelets but are unable to form shear-resistant aggregates ex vivo. Avian thrombocytes are larger than mammalian platelets, spread less efficiently on collagen, and express much lower levels of the α(₂b)β₃ integrin required for aggregate formation, features predicted to make thrombocyte aggregates less resistant than platelets are to the high fluid shear forces of the arterial vasculature. In vivo carotid vessel injury stimulates the formation of occlusive platelet thrombi in mice but not in the size- and flow-matched carotid artery of the Australian budgerigar. These studies indicate that unique physical and molecular features of mammalian platelets enable them to form shear-resistant arterial thrombi, an essential element in the pathogenesis of human cardiovascular diseases.

Therapeutic contraindications in exotic pets

Abstract Therapeutic drugs legally available for human use have gone through exhaustive pharacodynamic testing and clinical drug trials. Far fewer drugs have been evaluated for common companion animals such as dogs and cats, and practically none have been rigorously evaluated for the exotic patient. Much of our information on dosing, efficacy, and adverse reactions is anecdotal or based on extrapolation from other species. Very little information exists on drug-to-drug interaction in vivo. However, a few recognized therapeutic contraindications exist, and many have been well documented in the field of laboratory medicine. A common example is corticosteroid usage in laboratory rabbits. The exotic animal practitioner needs to be fully aware of these limitations and implications and be willing to perform a thorough literature search for already established information when contemplating the use of a novel drug in exotic animal species.

Psittacine Plasma Concentrations of Elements: Daily Fluctuations and Clinical Implications

During the past 2 decades, the potential for excessive exposure of pet birds to zinc has become a concern for many pet bird owners. Ideally, avian zinc toxicosis is diagnosed on the basis of history of exposure to zinc, radiographic evidence of ingested metal, occurrence of melena, detection of an elevated plasma zinc concentration, and response to treatment. However, most pet birds suspected of having zinc toxicosis present with vague signs and lack of radiographic evidence; therefore, the diagnosis relies on the presence of an elevated plasma zinc concentration. A question was, is there a significant diurnal variation in the zinc concentration in psittacine birds and could this be clinically relevant? Because studies in other species have shown that zinc is not the only element that shows a diurnal variation, the authors examined 13 other plasma elements including arsenic, cadmium, calcium, cobalt, copper, iodine, iron, magnesium, manganese, molybdenum, potassium, selenium, and total phosphorus. Fifteen adult psittacine birds housed in the same aviary were used in this study. Three blood samples, separated by 4 hours, were taken from the right jugular vein in each bird. All elements were measured in plasma. Zinc, copper, and molybdenum revealed diurnal fluctuations. The results of this study suggest that interpretation of clinical samples may be more complicated than previously believed. Furthermore, on the basis of the results of this study, it is possible that some avian reference ranges may need to be reexamined.

Selected Complete Blood Cell Count and Plasma Protein Electrophoresis Parameters in Pet Psittacine Birds Evaluated for Illness

Abstract Veterinarians rely on results of both the complete blood cell count (CBC) and plasma protein electrophoresis (EPH) in conjunction with the results of the plasma biochemical analysis to evaluate the health status of avian patients. Because the CBC and protein EPH measure different aspects of the immune response to disease, both tests are recommended in avian patients to rule out infectious or inflammatory disease. To evaluate results of the CBC and protein EPH in pet psittacine birds, the records of 144 pet psittacine birds, comprising 11 genera, that were presented for suspected illness were reviewed. Results of the CBC (total white blood cell count and packed cell volume) and protein EPH (alpha, beta, and gamma globulin concentrations) from submitted blood samples from each bird were evaluated. Of the 144 birds, 63 (43.8%) had abnormal CBC results, and 25 (17.4%) had abnormal EPH measurements. Results of the CBC and protein EPH were within reference ranges in 73 birds (50.7%). Abnormal results of the CBC in conjunction with normal EPH results were present in 46 birds (31.9%), compared with 8 birds (5.6%) with normal results of the CBC and abnormal EPH results. The findings of this study could aid practitioners in evaluating psittacine patients and prioritizing the value of individual diagnostic tests.

Methicillin-resistant Staphylococcus aureus-associated dermatitis in a Congo African grey parrot (Psittacus erithacus erithacus).

Abstract A 2-year-old DNA-sexed female Congo African grey parrot (Psittacus erithacus erithacus) was evaluated for self-trauma of the feathers and skin of the tail base for a duration of more than 1 year. All rectrices and tail coverts were missing, the skin of the tail base was thickened and ulcerated, and the uropygial gland was swollen. Results of a complete blood cell count revealed relative monocytosis and basophilia. Survey radiographs showed truncation and lysis of the caudal vertebrae and pygostyle. Results of biopsy and bacterial culture of the tail base lesions revealed an ulcerative bacterial dermatitis positive for staphylococcal cassette chromosome mec (SCCmec) type IV (community-acquired) methicillin-resistant Staphylococcus aureus (MRSA). The bird was treated with oral trimethoprim-sulfamethoxazole, meloxicam, fluoxetine, topical lidocaine gel, and hydrotherapy. One month later, tail feather regrowth was evident; however, follow-up over 2 years found continued self-trauma to the rectrices in spite of repeated skin biopsies negative for MRSA or other bacteria. It is unknown if the MRSA cultured from this bird was commensal or acquired from either the environment or humans to which the bird was exposed.

Intraocular osteosarcoma in an Umbrella Cockatoo (Cacatua alba).

An adult, presumed intact female Umbrella Cockatoo (Cacatua alba), presented with acute hemorrhage from an intraocular mass that perforated through the right cornea. Computed tomography scanning revealed a large soft tissue mass in the right orbit, invading and displacing the globe laterally, and destroying the scleral ossicles. There was no evidence of bony changes of the orbit or extension of the mass into the optic nerve or brain. Exenteration and mass removal were performed, and osteosarcoma was diagnosed via histopathology. Radiotherapy was delivered with an orthovoltage unit to a total dose of 68 Gray delivered in 17 fractions over 6 weeks. The bird recovered well from treatment, but died 2 months after the last radiation session with neurological signs. Necropsy was not performed. To our knowledge, this is the first case of an intraocular osteosarcoma reported in a bird, and the first case of attempted treatment of osteosarcoma in a bird by a combination of surgery and radiation therapy.

Evaluation of mucosal and seborrheic sites for staphylococci in two populations of captive psittacines.

OBJECTIVE To survey 2 populations of psittacines to characterize Staphylococcus spp isolated from commensal cutaneous microflora. DESIGN Prospective cross-sectional study. ANIMALS 107 psittacine birds from a sanctuary and 73 psittacine birds in private households or a pet store. PROCEDURES Gram-positive, catalase-positive cocci isolated from mucosal and seborrheic sites were speciated, and pulsed-field gel electrophoresis was performed on coagulase-positive isolates. A bird was classified as having positive results when at least 1 sample site yielded positive results for at least 1 staphylococcal species. RESULTS 89 of 180 (49.4%) birds had positive results for staphylococci at the carriage sites sampled. Privately owned birds were twice as likely to have positive results for staphylococci as were sanctuary birds (71% vs 35%). Coagulase-positive staphylococci were significantly more common in the sanctuary birds (47% vs 1%). Staphylococcus intermedius was significantly more common in the sanctuary birds (46% vs 2%). Staphylococcus hominis subsp hominis and Staphylococcus epidermidis, coagulase-negative staphylococci associated with humans, were significantly more common in pet birds. Cockatoos were twice as likely to have positive results for staphylococci as were other genera. CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that staphylococcal colonization in captive psittacines was less common than in other species studied. Staphylococci isolated from a pet psittacine may reflect that of the humans and other animals with which the bird lives in close proximity; however, further studies are needed to evaluate the effects exposure to humans may have on the microflora of these birds.

CASE REPORT: Intraocular osteosarcoma in an Umbrella Cockatoo (Cacatua alba)

An adult, presumed intact female Umbrella Cockatoo (Cacatua alba), presented with acute hemorrhage from an intraocular mass that perforated through the right cornea. Computed tomography scanning revealed a large soft tissue mass in the right orbit, invading and displacing the globe laterally, and destroying the scleral ossicles. There was no evidence of bony changes of the orbit or extension of the mass into the optic nerve or brain. Exenteration and mass removal were performed, and osteosarcoma was diagnosed via histopathology. Radiotherapy was delivered with an orthovoltage unit to a total dose of 68 Gray delivered in 17 fractions over 6 weeks. The bird recovered well from treatment, but died 2 months after the last radiation session with neurological signs. Necropsy was not performed. To our knowledge, this is the first case of an intraocular osteosarcoma reported in a bird, and the first case of attempted treatment of osteosarcoma in a bird by a combination of surgery and radiation therapy.

CASE REPORT: Intraocular osteosarcoma in an Umbrella Cockatoo (Cacatua alba): intraocular osteosarcoma in an umbrella cockatoo

An adult, presumed intact female Umbrella Cockatoo (Cacatua alba), presented with acute hemorrhage from an intraocular mass that perforated through the right cornea. Computed tomography scanning revealed a large soft tissue mass in the right orbit, invading and displacing the globe laterally, and destroying the scleral ossicles. There was no evidence of bony changes of the orbit or extension of the mass into the optic nerve or brain. Exenteration and mass removal were performed, and osteosarcoma was diagnosed via histopathology. Radiotherapy was delivered with an orthovoltage unit to a total dose of 68 Gray delivered in 17 fractions over 6 weeks. The bird recovered well from treatment, but died 2 months after the last radiation session with neurological signs. Necropsy was not performed. To our knowledge, this is the first case of an intraocular osteosarcoma reported in a bird, and the first case of attempted treatment of osteosarcoma in a bird by a combination of surgery and radiation therapy.