Malignant B-cell lymphoma of the Harder's gland in a rabbit

A 22-month-old, female rabbit was presented with a 1-day history of acute unilateral exophthalmos. Ultrasonography and computed tomography (CT) of the orbit revealed an orbital mass. Retrobulbar lymphoma was diagnosed following fine-needle aspiration biopsy (FNAB). Thoracic radiographs were normal, and ultrasonography of the abdomen showed focal hypoechoic thickening of the bowel wall and hypoechoic enlarged lymph nodes. The rabbit was euthanized and histopathology identified the retrobulbar mass as B-cell malignant lymphoma of the Harder's gland. Mesenteric lymph nodes, caecum, and both kidneys were also affected. This is the first documented case of malignant lymphoma of the Harder's gland in a rabbit.     

Investigation of characteristics and factors associated with avian mycobacteriosis in zoo birds.

The objective of the current study was to identify factors associated with avian mycobacteriosis in zoo birds. Inventory data, population health records, and necropsy data from eligible birds in the Zoological Society of San Diego's (ZSSD) collection from 1991-2005 (n = 13,976) were used to describe disease incidence, prevalence, and postmortem findings. A matched case-control study was then conducted to identify factors describing demographic, temporal, and enclosure characteristics, along with move and exposure histories. Cases (disease-positive birds; n = 167) were matched in a 17 ratio with controls (disease-negative birds; n = 1169) of similar age and taxonomic grouping. Potential risk factors were evaluated using univariate and multivariable conditional logistic regression. Disease prevalence and incidence were estimated for the study period at 1.2% and 3 cases/(1,000 bird-years at risk), respectively. Lesion characteristics and order prevalence are described. In the multivariable model, case birds were more likely to have been previously housed with a bird with mycobacterial disease involving the intestinal tract (odds ratio [OR] = 5.6, P < 0.01) or involving only nonintestinal sites (OR = 2.0, P < 0.01). Cases were more likely to have been imported into the collection than hatched at the ZSSD (OR = 4.2, P < 0.01). Cases were moved among ZSSD enclosures more than controls (OR = 1.1 for each additional move, P < 0.01). Findings will help guide future management of this disease for zoo bird populations.     

Hepatic hemorrhage, hemocoelom, and sudden death due to Haemoproteus infection in passerine birds: eleven cases.

Haemoproteus spp. are ancient apicomplexan hemoparasites that have undergone extensive coevolution with their natural hosts and are typically species specific, with inapparent or minimal pathogenicity. A promiscuous genotype of Haemoproteus capable of undergoing host switching on a familial level was identified. This protozoan caused severe disease with high mortality in 6 species of exotic passerine birds housed in California at the San Diego Zoo's Wild Animal Park: Surinam crested oropendola (Psarocolius decumanus decumanus), Guianan turquoise tanager (Tangara mexicana mexicana), blue-necked tanager (Tangara cyanicollis caeruleocephala, Guianan red-capped cardinal (Paroaria gularis gularis), magnificent bird of paradise (Diphyllodes magnificus hunsteini), and superb bird of paradise (Lophorina superba). The birds had few or no clinical signs. Necropsy findings consisted of hemocoelom and irregularly scattered areas of hemorrhage and hepatocellular necrosis. Affected areas of liver contained solitary protozoal megaloschizonts in varied states of degeneration and peripheral nonsuppurative inflammation. No other parasite life stages were found in parenchymal organs or blood smears. Polymerase chain reaction using consensus primers for an avian malarial mitochondrial cytochrome B gene segment was positive in all cases. Sequencing and BLAST analysis identified the protozoan as a Haemoproteus sp. related to Haemoproteus spp. found in asymptomatic passerine birds native to North America. In situ hybridization was performed in 3 animals with a mitochondrial cytochrome B probe and was positive only in megaloschizonts. These findings suggest the recognition of a genotype of Haemoproteus that exhibits high levels of host infidelity and causes severe disease in captive birds exotic to North America.     

Landscape perception by forest understory birds in the Atlantic Rainforest: black-and-white versus shades of grey

Even among forest specialists, species-specific responses to anthropogenic forest fragmentation may vary considerably. Some appear to be confined to forest interiors, and perceive a fragmented landscape as a mosaic of suitable fragments and hostile matrix. Others, however, are able to make use of matrix habitats and perceive the landscape in shades of grey rather than black-and-white. We analysed data of 42 Chiroxiphia caudata (Blue Manakin), 10 Pyriglena leucoptera (White-shouldered Fire-eye) and 19 Sclerurus scansor (Rufous-breasted Leaftosser) radio-tracked in the Atlantic Rainforest of Brazil between 2003 and 2005. We illustrate how habitat preferences may determine how species respond to or perceive the landscape structure. We compared available with used habitat to develop a species-specific preference index for each of six habitat classes. All three species preferred old forest, but relative use of other classes differed significantly. S. scansor perceived great contrast between old forest and matrix, whereas the other two species perceived greater habitat continuity. For conservation planning, our study offers three important messages: (1) some forest specialist species are able to persist in highly fragmented landscapes; (2) some forest species may be able to make use of different anthropogenic habitat types to various degrees; whereas (3) others are restricted to the remaining forest fragments. Our study suggests species most confined to forest interiors to be considered as potential umbrella species for landscape-scale conservation planning.     

Efficacy of a modified live intranasal bovine respiratory syncytial virus vaccine in 3-week-old calves experimentally challenged with BRSV

Two experimental bovine respiratory syncytial virus (BRSV) challenge studies were undertaken to evaluate the efficacy of a single intranasal dose of a bivalent modified live vaccine containing BRSV in 3-week-old calves. In the first study, vaccine efficacy was evaluated in colostrum deprived (maternal antibody negative) calves 5, 10 and 21 days after vaccination. Nasal shedding of BRSV was significantly reduced in vaccinated calves challenged 10 or 21 days after vaccination. Virus excretion titres were also reduced in vaccinates challenged 5 days after vaccination but reduction in duration of shedding and total amount of virus shed were not statistically significant. Clinical disease after challenge in this study was mild. In the second study, vaccine efficacy was assessed in calves with maternal antibodies against BRSV by challenge 66 days post-vaccination. Vaccination significantly reduced nasal shedding after challenge and the severity of clinical disease was also reduced.     

Disturbed Vasopressin Release in 4 Dogs with So-Called Primary Polydipsia

Primary polydipsia is characterized by a marked increase in water intake and secondary polyuria, and in dogs often is described as a behavioral problem or a psychological disorder. We describe 4 dogs with primary polydipsia, diagnosed on the basis of a modified water deprivation test, in which further examination included serial measurements of urine osmolality (UOsm) and plasma vasopressin (VP) measurements during water deprivation and hypertonic saline infusion. The dogs, ranging in age from 4 months to 4 years, all were presented for evaluation of polyuria and polydipsia. Physical examination, routine blood chemistry, and urinalysis disclosed no specific cause for the polyuria and polydipsia. During serial measurements UOsm spontaneously reached high concentrations in 2 dogs, whereas in the other 2 dogs UOsm also fluctuated but on no occasion exceeded 1,000 mosm/kg. Primary polydipsia was diagnosed when UOsm exceeded 1,000 mosm/kg at the end of the modified water deprivation test and plasma osmolality did not exceed the upper limit of the reference range during testing. During water deprivation, plasma VP concentrations remained relatively low. The VP response to hypertonic saline infusion was abnormal, with an increased threshold value in 3 dogs, an increased sensitivity in 2 dogs, and an exaggerated response in 1 dog. It is concluded that some dogs fulfilling current criteria for primary polydipsia produce concentrated urine spontaneously throughout the day in a pattern similar to what has been observed in healthy pet dogs. This finding can be regarded as diagnostic and precludes the need for a water deprivation test. During water deprivation testing, all 4 dogs produced highly concentrated urine in the face of low basal plasma VP concentrations. The observed abnormal VP release in response to hypertonic stimulation may be interpreted as a primary disturbance in the regulation of VP secretion, although it might also be the result of overhydration caused by a primary abnormality in drinking behavior.