Sonographic evaluation of thyroid morphology during the normal estrous cycle in the Indo-Pacific bottlenose dolphin (Tursiops aduncus).

Physiologic changes occurring in the thyroid in response to the estrous cycle have been noted in companion animals. However, in bottlenose dolphins, the influence of different reproductive states on thyroid morphology remains unclear. Sonography was used to evaluate the variations of thyroid morphology for nine consecutive estrous cycles of four sexually mature, female Indo-Pacific bottlenose dolphins (Tursiops aduncus). The estrous cycle was divided into two phases for evaluation: the follicular and luteal phases. To compare changes associated with sex, thyroid volumes were measured in the different phases during the estrous cycle of female dolphins and were compared to the ultrasound examinations of the four male dolphins measured over a 2-mo period. In males, there was no significant difference in thyroid volume during the study period (P > 0.05). The thyroid volume measured in combining all estrous cycle phases of the female dolphins was significantly larger than that measured in the male dolphins (P < 0.05). A difference in thyroid volume during the estrous cycle was observed, with the thyroid volume during the follicular phase significantly smaller (P < 0.05) than that of the luteal phase, and is possibly related to the influence of female sex steroids. Thyroid volume variability during estrus should, therefore, be taken into account when examining the thyroid gland of female dolphins.

Evaluation of two-dimensional and three-dimensional ultrasound in the assessment of thyroid volume of the Indo-Pacific bottlenose dolphin (Tursiops aduncus).

The assessment of thyroid volume plays an indispensable role in the diagnosis and management of different thyroid diseases. The present study evaluates the accuracy of dolphin thyroid volume measurement as determined by four two-dimensional (2D) ultrasound methods (A-D), with a standard of reference using three-dimensional (3D) ultrasound. The measurement accuracy for different recognized thyroid configuration is also evaluated. Inter- and intraoperator variability of the measurement methods was determined. Thyroid ultrasound examinations were conducted in 16 apparently healthy Indo-Pacific bottlenose dolphins (Tursiops aduncus) with 2D and 3D ultrasound under identical scanning conditions. All 2D ultrasound measurement methods yielded high accuracies (79.9-81.3%) when compared with the 3D ultrasound measurement, and had high measurement reproducibility (77.6-86.2%) and repeatability (78.1-99.7%). For 2D ultrasound measurements, Methods A and B were more accurate and reliable than Methods C and D, regardless of thyroid configuration. Ultrasound is useful in the measurement of thyroid volume in bottlenose dolphins. For the first time, a reliable ultrasound scanning protocol for measuring dolphin thyroid volume was developed, which provides a means to establish a normative reference for the diagnosis of thyroid pathologies and to monitor the thyroid volume during the course of treatment in living dolphins. Key words: 3D ultrasound, Indo-Pacific bottlenose dolphin, thyroid volume measurement, Tursiops aduncus.

Seroprevalence of dogs in Hong Kong to human and canine influenza viruses.

As a unique mammalian host for influenza A viruses, dogs support the transmission of canine influenza viruses (CIVs) of H3N8 and H3N2 subtypes and are susceptible to infection by avian and human influenza viruses. A cross-sectional serological study was performed to assess the exposure history of dogs in Hong Kong to CIV and human influenza viruses. Among 555 companion dogs sampled in 2015-2017, 1.3 per cent and 9.5 per cent showed hemagglutination inhibition (HI) antibody titre to CIV of H3N8 or H3N2 subtypes and to A(H1N1)pdm09 human influenza viruses, respectively. Among 182 shelter dogs sampled in 2017-2018, none showed HI titre to CIV and 1.1 per cent reacted to H3N2 human influenza virus. There was a poor correlation between ELISA and HI test results. The higher seropositive rates to human influenza viruses suggests that the contact dynamics of dogs under urban settings may affect the exposure risk to human influenza viruses and CIVs.

Bronchoscopy of cetaceans.

Bronchoscopy is a standard diagnostic and therapeutic procedure in respiratory medicine and has been performed on many animal species. Cetaceans suffer considerable morbidity and mortality from lower respiratory tract infections, and it is very difficult to sample lower respiratory tract secretions for microbiology and other analyses. We report our experience on performing fiberoptic bronchoscopy in three bottle-nosed dolphins (Tursiops truncatus) and one false killer whale (Pseudorca crassidens), which should help other clinicians in performing bronchoscopy in cetaceans.

Ultrasonographic assessment of the thyroid gland and adjacent anatomic structures in Indo-Pacific bottlenose dolphins (Tursiops aduncus).

OBJECTIVE: To evaluate the use of ultrasonography for thyroid gland assessment in healthy Indo-Pacific bottlenose dolphins (Tursiops aduncus), describe the ultrasonographic appearance of the thyroid gland and adjacent anatomic structures, and identify potential associations between variations in thyroid gland morphology and demographic features in this species. ANIMALS: 18 captive Indo-Pacific bottlenose dolphins. PROCEDURES: 1,404 ultrasonographic examinations of the thyroid gland and adjacent anatomic structures (eg, cervical lymph nodes, musculature, and vasculature) were performed during the > 3-year study period. Shape, echogenicity, and homogeneity of thyroid glands were assessed, and glands were categorized into morphological configurations on the basis of results of 2-D and 3-D ultrasonographic evaluation. Associations between demographic factors and thyroid gland morphology were assessed. RESULTS: Thyroid lobes appeared elliptical or fusiform in the transverse scan plane and round to oval in longitudinal scan planes; morphologically, glands comprised 2 lobes joined by an isthmus or a roughly diamond-shaped structure located on the ventral surface of the trachea. Major blood vessels and cervical lymph nodes were identified. Thyroid parenchyma was typically uniform and homogeneous, with echogenic reticulations and well-defined borders. Thyroid glands were hypoechoic or isoechoic relative to the sternocephalicus muscle; echogenicity was greater in adolescents than in adults. Thyroid gland volume differed between sexes, between sexually mature and immature dolphins, and among age groups and was positively correlated with body length and weight. CONCLUSIONS AND CLINICAL RELEVANCE: Ultrasonography provided a reliable and repeatable method for evaluation of thyroid glands and adjacent anatomic structures in live dolphins.

Reliability of 2D ultrasound measurements of testis size in dolphins taken under voluntary behavior.

This study was undertaken to evaluate the reliability of two-dimensional (2D) ultrasound in measuring testis size in dolphins, in vivo, with the subject presenting for examination under voluntary or trained behaviour. The testes of five bottlenose dolphins (Tursiops aduncus) were measured once by two operators to test inter-operator variability (reproducibility) and repeatedly measured by the same operator to test intra-operator variability (repeatability). Ultrasound examinations for each test were conducted on the same day to avoid measurement variability due to time difference. The evaluation of reproducibility and repeatability were conducted on separate days. In the ultrasound examination, the length, circumference, depth and width of both testes of the animal were measured. To prevent bias, measurements were not communicated between the operators on-site and repeated measurements were masked. Results showed that both reproducibility and repeatability of all the testis measurements were high (>90%). Overall, measurement variability of the technique was found to be of a satisfactory level. Ultrasound is a useful imaging tool for routine long-term monitoring of the testes in this species of animals. Sources of error due to movements as a result of the subject being in the water during examinations were inevitable and must be taken into account.

Semen collection and ejaculate characteristics in the Indo-Pacific bottlenose dolphin (Tursiops aduncus).

The testes of sexually mature dolphins produce large quantities of sperm. Sperm are expelled in copious amounts of seminal fluid through repeated ejaculations that can occur within a short period of time. There is currently a lack of detail about the methodology of sequential ejaculate collection in dolphins and how the traits of individual ejaculates affect the assessment of reproductive capacity. The objectives of this study were to obtain series of ejaculates from 3 dolphins by following a well-defined collection protocol and then to characterize individual ejaculates. Semen was collected weekly for 1 year from 3 sexually mature Tursiops aduncus. The end of a collection session was marked by a lack of semen, in spite of effort, or micturition. Individual ejaculates were analyzed for volume, pH, and sperm concentration, count, motility, and viability following methods previously described for dolphin semen. The first ejaculate was typically higher in volume and sperm count but lower in sperm concentration, motility, and viability. The concentration of the second ejaculate was generally the highest. Sperm motility and viability of the second and subsequent ejaculates in a series were good (ie, >80%). Collection of the first ejaculate only can lead to underestimation of reproductive capacity. Sperm output fluctuated erratically from week to week, so it was difficult to assess any seasonal pattern. Results provide information for further investigation of male dolphin reproductive patterns and any effect of collection frequency on ejaculate characteristics.

Multilocus sequence typing and evolutionary relationships among the causative agents of melioidosis and glanders, Burkholderia pseudomallei and Burkholderia mallei.

A collection of 147 isolates of Burkholderia pseudomallei, B. mallei, and B. thailandensis was characterized by multilocus sequence typing (MLST). The 128 isolates of B. pseudomallei, the causative agent of melioidosis, were obtained from diverse geographic locations, from humans and animals with disease, and from the environment and were resolved into 71 sequence types. The utility of the MLST scheme for epidemiological investigations was established by analyzing isolates from captive marine mammals and birds and from humans in Hong Kong with melioidosis. MLST gave a level of resolution similar to that given by pulsed-field gel electrophoresis and identified the same three clones causing disease in animals, each of which was also associated with disease in humans. The average divergence between the alleles of B. thailandensis and B. pseudomallei was 3.2%, and there was no sharing of alleles between these species. Trees constructed from differences in the allelic profiles of the isolates and from the concatenated sequences of the seven loci showed that the B. pseudomallei isolates formed a cluster of closely related lineages that were fully resolved from the cluster of B. thailandensis isolates, confirming their separate species status. However, isolates of B. mallei, the causative agent of glanders, recovered from three continents over a 30-year period had identical allelic profiles, and the B. mallei isolates clustered within the B. pseudomallei group of isolates. Alleles at six of the seven loci in B. mallei were also present within B. pseudomallei isolates, and B. mallei is a clone of B. pseudomallei that, on population genetics grounds, should not be given separate species status.