Congenital hypodontia in three horses diagnosed by computed tomography

Dental agenesis is a congenital disease defined as failure of formation of one or more teeth, which has been extensively described in human literature and that has been documented in several other species including cats, dogs, seals and sea lions, mice, and ungulates. The aim of this study was to review the clinical and computed tomographic (CT) features of tooth agenesis in a population of horses. Retrospective review of the imaging records from the Langford Equine Hospital was performed, including all horses that underwent head CT between January 2015 and June 2017. Of a total number of 167 CT scans, three horses with hypodontia were found. All three cases had agenesis of the maxillary 08s and one case had additional agenesis of the 307 and 308 teeth. Delayed resorption of the corresponding deciduous teeth was reported in all cases. The empty space left by the absent teeth was filled either by heterogeneous bone tissue alone (two cases) or by a combination of bone and soft tissue (one case). Alignment between teeth was preserved, and there was no displacement of the neighbouring teeth adjacent to the agenesis site. All three horses presented a symmetric pattern of dental agenesis within the maxillary arcades. The maxillary 08s, which are the latest to erupt, were the most affected teeth. This was similar to that reported in human literature, where the teeth that form later during development are the most vulnerable to dental agenesis.     

Inherited defects in pedigree dogs. Part 2: Disorders that are not related to breed standards

Recent debate concerning health problems in pedigree animals has highlighted gaps in current knowledge of the prevalence, severity and welfare implications of deleterious inherited traits within the pedigree-dog population. In this second part of a two-part review, inherited disorders in the top 50 UK Kennel Club registered breeds were researched using systematic searches of existing databases. A set of inclusion and exclusion criteria, including an evidence strength scale (SEHB), were applied to search results. A total of 312 non-conformation linked inherited disorders was identified, with German shepherd dogs and Golden retrievers associated with the greatest number of disorders. The most commonly reported mode of inheritance was autosomal recessive (71%; 57 breed-disorder combinations), and the most common primarily affected body system was the nervous sensory system. To provide a true assessment of the scale of inherited disorders in the pedigree dogs studied more effort is required to collect accurate prevalence data.     

The effect of the time interval between exposures on the susceptibility of chickens to superinfection with Marek's disease virus

Marek's disease virus (MDV) is ubiquitous within commercial poultry flocks because current vaccines do not prevent MDV infection or transmission. In order for newly-evolved MDV strains to become established within a flock, it seems inevitable that any new strain would need to infect and replicate in chickens previously infected with resident MDV strains. This phenomenon is difficult to detect and there is no clear evidence that it is even possible. Four experiments were performed to demonstrate superinfection and evaluate the effect of time between challenges on the effect of superinfection with the use of two pairs of fully virulent MDV strains that could be discriminated by novel technology: 1) JM/102W and rMd5//38CVI, and 2) rMd5 and rMd5//38CVI. Feather follicle epithelium (FFE), spleen, and tumor samples were collected at single or multiple time points from the same bird to determine the frequency and distribution of each virus present following superinfection, with the use of pyrosequencing and immunohistochemistry. Superinfection was observed in 82 of 149 (55%) FFE samples following short-interval challenge (24 hr) compared to only 6 of 121 (5%) samples following long-interval challenge (13 days), indicating a strong influence of challenge interval. In cases where the first inoculated virus was weak or delayed, the second inoculated virus was detected in 42 of 95 (44%) birds. In tumors from dually challenged birds, the second virus was again present much more often following short-interval challenge (68%) compared to long-interval challenge (11%). Virus mixtures in tumors were less common compared to those in FFE samples. Vaccination with turkey herpesvirus had no significant effect on the virus frequency for either virus pair or challenge time interval, suggesting these conclusions may be applicable to vaccinated chickens in the field. These studies demonstrated superinfection for the first time with two fully virulent MDV strains and suggest that short-interval challenge exposure and/or weak initial exposures may be important factors leading to superinfection--a prerequisite for the establishment of a second virus strain in the population. This model system should be useful to elucidate this important phenomenon further.     

Ghosts of the coast: global extinction risk and conservation of sawfishes

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Characterization of Pectobacterium carotovorum subsp. carotovorum and brasiliense from diseased potatoes in Kenya

Using a DNA-based typing method, 48 bacterial strains isolated from infected potato (Solanum tuberosum) tubers originating from Kenya were characterized. The pel gene specific primers showed that all the 48 bacterial strains were pectolytic. Subspecies-specific primers EXPCCF/EXPCCR and Br1f/L1r identified 66 % of the strains as Pectobacterium carotovorum subsp. carotovorum while 34 % were identified as Pectobacterium carotovorum subsp. brasiliense based on their characteristic band sizes of 550 and 322 bp, respectively. Amplification of the 16S-23S rDNA (ITS) region did not yield observable differences in banding patterns between the Kenyan strains. However, PCR-RFLP analysis together with partial nucleotide sequences of the housekeeping mdh and gapA genes confirmed the results obtained by the specific primers. Phylogenetic analysis of the concatenated partial gene sequences grouped Pectobacterium carotovorum subsp. carotovorum and Pectobacterium carotovorum subsp. brasiliense Kenyan strains together with those identified in other parts of the world with 90 % and 99 % bootstrap support values, respectively. Pathogenicity assays using representative Kenyan strains demonstrated varied levels of tuber maceration ability. The Pectobacterium carotovorum subsp. carotovorum and Pectobacterium carotovorum subsp. brasiliense Kenyan strains were shown to be less aggressive in causing soft rot when compared to type strains. This study describes for the first time the genetic diversity of pectolytic bacteria causing soft rot disease of potatoes in Kenya.     

Epidemiology of extended spectrum beta-lactamase E. coli (CTX-M-15) on a commercial dairy farm

The epidemiology of an extended spectrum beta-lactamase Escherichia coli (CTX-M-15) was observed and described on a commercial dairy farm located in the United Kingdom. During 2008 longitudinal sampling of faecal pat samples from different cattle groups comprising milking and non-milking cows, calving cows, calves, and the environment was carried out. The proportion of CTX-M-15 E. coli positive samples was significantly (p<0.0.01) higher in milking cows (30.3%, CI(95%) 26.8; 33.8) than in the herd as a whole (17.0%, CI(95%) 14.9; 19.0). In 2008 95.6% of sampled calves tested positive for CTX-M-15 E. coli at two days of age. A more detailed investigation in 2009 revealed that cows and heifers were approximately eight times more likely to test positive in the 10 days after calving than the 9 days before (OR 7.6, CI(95%) 2.32; 24.9). The CTX-M15 E. coli was also readily isolated from the immediate calving pen environment, including the water troughs. A cyclic pattern was apparent where cows immediately after calving and as high yielders were highly positive, but where the prevalence decreased during the dry period. The increased prevalence of the CTX-M-15 E. coli in certain cattle groups and farm environments including calving pens suggested that husbandry, antimicrobial usage and hygiene may play a significant role on a farm with regards to the epidemiology of CTX-M-15. This may offer a practical opportunity to reduce further dissemination through good practice and hygiene around calving.     

Viral nucleoprotein localization and lesions of Newcastle disease in tissues of indigenous ducks

Localization of Newcastle disease viral nucleoprotein and pathological lesions was evaluated in tissues of 55 indigenous ducks (45 experimentally infected and 10 sentinel ones). In addition, ten Newcastle disease infected chickens were used to ensure that the virus inoculum administered to the ducks produced the disease in chickens, the susceptible hosts. Ducks were killed on day 1, 4, 8 and 14 post-infection. Post-mortem examination was done with six tissues (liver, spleen, lung, caecal tonsils, kidneys and brain) being collected from each bird. The tissues were preserved in 10% neutral formalin for 24 h. They were then transferred to 70% ethanol for histology and immunohistochemical staining. Airsacculitis, necrotic splenic foci, congested intestines, lymphoid depleted caecal tonsils and focal infiltrations by mononuclear cells were the main pathological lesions in infected ducks. Over 28.9% of the infected ducks had Newcastle disease viral nucleoprotein in macrophage-like large mononuclear cells in the caecal tonsils and kidney tubular epithelium. The viral antigens were located in the cytoplasm and nucleolus of the cells. The other organs had no detectable viral antigens. This study shows that the kidneys and caecal tonsils are the likely predilection sites for the virus in ducks. They thus need to be considered as diagnostic indicators for the viral carriage in ducks.