Factors affecting the immunogenicity of Pasteurella haemolytica in mice

An appreciable level of immunity from intraperitoneal infection with Pasteurella haemolytica was established in mice by using a vaccine prepared in a conventional bacteriological culture medium, with aluminium hydroxide gel as adjuvant. The level of immunity could not be elevated by using bacteria grown in tissue culture media, enriched brain heart infusion broth, the addition of serum to the media or by using bacteria that had been harvested in the logarithmic growth phase. Although various extracts of the bacteria elicited a distinct immunity, the immunogenicity of vaccines containing bacteria could not be enhanced by augmentation with those products. The potential application of the vaccine in cattle and sheep is discussed.     

Field immobilisation of southern elephant seals with intravenous tiletamine and zolazepam

Southern elephant seals (Miroungo leonina) were immobilised with a mixture of tiletamine and zolazepam administered intravenously at a mean (sd) dose rate of 0.46 (0.08) mg/kg. This dose provided a satisfactory degree of anaesthesia with no side effects, and the induction, duration and recovery times were short. The mean (sd) induction time was 26 (9) seconds and the mean level of anaesthesia was 4.4 units on an eight-point scale. Male seals were given less drug than female seals, remained immobilised for shorter periods and recovered sooner. The mean (sd) dose of drug administered to males was 0.44 (0.06) mg/kg and to females 0.48 (0.08) mg/kg, and the mean (sd) duration times were 14.9 (4.5) minutes and 16.1 (5.3) minutes. The mean (sd) time taken to recover from immobilisation was 14.5 (4.6) minutes for males and 15.7 (5.3) minutes for females. Physiological condition and size significantly affected the duration of anaesthesia. Thin seals remained immobilised for 18 (7) minutes whereas fatter seals remained immobilised for 15 (4) minutes (P<0.0001).     

The human-canine environment: a risk factor for non-play bites?

Few dog bite risk factor studies have been conducted. This veterinary clinic-based retrospective cohort study was aimed at identifying human-canine environmental risk factors for non-play bites in Kingston, Jamaica (660) and San Francisco (SF), USA (452). Data were analysed using modified Poisson regression with confounders selected using directed acyclic graphs (DAGs) and the change-in-estimate procedure. Dogs acquired for companionship were more likely (RR=1.66; 95% CI 1.02-2.70) to bite than those acquired for protection. Routinely allowing a dog into the presence of visitors was also positively associated with it biting. A dog sleeping in a family member's bedroom was a risk factor for biting in Kingston (RR=2.54; 95% CI 1.43-4.54) but not in SF, while being able to leave the yard unaccompanied was a risk factor for biting in SF (RR=3.40; 95% CI 1.98-5.85) but not in Kingston. Overall, dogs which were less restricted in their interactions with humans were at elevated risk for biting. An observed association with dog bites in one cultural setting might not exist in another.     

Haemophilus somnus (Histophilus somni) in bighorn sheep.

Respiratory disease and poor lamb recruitment have been identified as limiting factors for bighorn-sheep populations. Haemophilus somnus (recently reclassified as Histophilus somni) is associated with respiratory disease in American bison, domestic sheep, and cattle. It is also harbored in their reproductive tracts and has been associated with reproductive failure in domestic sheep and cattle. Therefore, reproductive tract and lung samples from bighorn sheep were evaluated for the presence of this organism. Organisms identified as H. somnus were isolated from 6 of 62 vaginal but none of 12 preputial swab samples. Antigen specific to H. somnus was detected by immunohistochemical study in 4 of 12 formalin-fixed lung tissue samples of bighorn sheep that died with evidence of pneumonia. Notably, H. somnus was found in alveolar debris in areas of inflammation. The 6 vaginal isolates and 2 H. somnus isolates previously cultured from pneumonic lungs of bighorn sheep were compared with 3 representative isolates from domestic sheep and 2 from cattle. The profiles of major outer membrane proteins and antigens for all of the isolates were predominantly similar, although differences that may be associated with the host-parasite relationship and virulence were detected. The DNA restriction fragment length profiles of the bighorn-sheep isolates had similarities not shared with the other isolates, suggesting distinct phylogenetic lines. All of the isolates had similar antimicrobial profiles, but the isolates from the bighorn sheep produced less pigment than those from the domestic livestock, and growth of the former was not enhanced by CO2. Wildlife biologists and diagnosticians should be aware of the potential of these organisms to cause disease in bighorn sheep and of growth characteristics that may hinder laboratory detection.     

Otoscopic evaluation of the ear canal.

Otoscopic evaluation of the external ear canal and tympanic membrane is the first diagnostic procedure that should be performed in animals presented with otitis externa. It is important to become familiar with the normal structures of the ear to identify any abnormalities. The video otoscope greatly enhances visualization of these structures as well as aiding in retrieval of foreign bodies, biopsy of masses, and performance of a myringotomy. In some cases, a complete otoscopic examination is not possible on the first visit, and the animal may require anti-inflammatory medications or otic flushing to visualize the entire ear canal as well as the tympanic membrane. The purpose of the otoscopic examination is to address the otitis by evaluating the condition of the ear, looking for any masses or foreign bodies; noting the presence, consistency, and color of any exudate; and evaluating the patency of the tympanic membrane. Once a complete otic evaluation has been performed, additional diagnostics as well as a treatment plan can be formulated.     

Ecological determinants and risk areas of Striga hermonthica infestation in western Kenya under changing climate

Striga hermonthica (Del.) Benth is a parasitic weed that is damaging major cereal crops in sub-Saharan Africa (SSA). Although Striga is recognised as an agricultural scourge, there is limited information available indicating the extent of its growth and spread as impacted by the changing climate in Kenya. This study investigated the impact of current climate conditions and projected future (2050) climate change on the infestation of Striga hermonthica in the western Kenya region. Specifically, the study aimed to predict Striga hermonthica habitat suitability in five counties in the western Kenya region through using the maximum entropy (MaxEnt) model and bioclimatic, soil, topographic and land use, and land cover (LULC) variables. Striga hermonthica geolocations were collected and collated and ecological niche models were developed to determine the habitat suitability. The results showed that approximately 1767 km² (10% of the total study area) is currently highly suitable for Striga hermonthica occurrence. The future projections showed a range between 2106 km² (19% of the total study area) and 2712 km² (53% of the total study area) at the minimum carbon (RCP 2.6) and the maximum carbon emission scenarios (RCP 8.5) respectively. Elevation, annual precipitation, LULC, temperature seasonality and soil type were determined to be the most influential ecological predictor variables for Striga hermonthica establishment. The study revealed the importance of using climate, soil, topographic and LULC variables when evaluating agricultural production constraints such as Striga's prevalence. The methodology used in this study should be tested in other Striga affected areas.     

Tetratrichomonas spp. and Pentatrichomonas hominis are not persistently detectable after intravaginal inoculation of estrous heifers

Virgin heifers (44) were intravaginally inoculated at estrus with low (10(6)) or high (10(8)) doses of live Tetratrichomonas sp., Pentatrichomonas hominis (P. hominis), or Tritrichomonas foetus (T. foetus). Controls were inoculated with Diamond's trypticase yeast extract maltose media. Genital infection was determined by culture of cervico-vaginal mucus (CVM) in Schneider's media and InPouch TF as well as by polymerase chain reaction/restriction fragment length polymorphism (PCR/RFLP). The presence of trichomonads in fecal samples was determined by culture in Schneider's medium and PCR/RFLP. In CVM samples, tetratrichomonads were found by PCR/RFLP and Schneider's culture only sporadically at intermittent weeks. The presence of tetratrichomonads was not associated with the dose in the experimental vaginal inoculation since Tetratrichomonas sp. appeared more frequently in heifers inoculated with a low dose of tetratrichomonads than in heifers inoculated with a high dose of tetratrichomonads. Moreover, Tetratrichomonas spp. were isolated not only in heifers inoculated with tetratrichomonads but also in control heifers and in heifers inoculated with P. hominis. In feces, Tetratrichomonas spp. were frequently identified by culture in Schneider's and by PCR/RFLP in heifers of all groups. P. hominis was never found in CVM or feces by any method. Based on the common appearance of tetratrichomonads in feces and vaginal secretions, it appears that tetratrichomonads were detected periodically in the vagina of heifers as a consequence of repeated contamination from feces and not as a result of experimental infection. In summary, in this study, the strains of Tetratrichomonas sp. and P. hominis did not establish persistent infection in heifers.     

Variation in gross and histological appearance of the canine pars flaccida

The tympanic membrane is divided into the pars flaccida (PF) and pars tensa. Otoscopic differences in the appearance of the PF in the dog (flat vs. bulging) have been reported anecdotally. The purpose of this study was to histologically examine the canine PF to determine if differences exist between a flat and a bulging PF. We hypothesized that differences in the PF may be structural or due to an increased pressure in the middle ear. Four adult canine cadavers were used (two had bilateral bulging PF, two had bilateral flat PF). The ear specimens were fixed in 10% buffered neutral formalin, decalcified, routinely processed and stained with haematoxylin and eosin, toluidine blue (staining for mast cells), and Verhoeff-van Gieson (staining for elastic fibres). One blinded investigator evaluated each PF histologically. Seven ears (three with bulging PF, four with flat PF) were evaluated in the study. The PF was identified in all seven ears. No histological differences that distinguished a bulging PF from a flat PF were identified. Six ears were evaluated for the presence of mast cells and elastic fibres. Less than one mast cell per x40 field was identified in the PF in five of six ears. No elastic fibres were identified in any of the six PF. Based on the results of this study, it appears unlikely that there is a structural difference that accounts for a bulging PF. Therefore, there may be increased middle ear pressure in dogs with a bulging PF.     

Tusklessness and tusk fractures in free-ranging African savanna elephants (Loxodonta africana)

The incidence of tusklessness varies between free-ranging African elephant populations. Sex-linked genetic drift predicts 2 outcomes--the condition becomes fixed and sex-specific incidences diverge when populations are small and/or heavily poached. By contrast, for large and intact populations, tusklessness diminishes and there is no variation between sexes. We tested these predictions by comparing sex-specific incidences between 15 populations: a small one with a skewed founder effect towards tusklessness; 5 that had experienced intense levels of poaching; 2 that had been subjected to non-selective culling and 7 that are relatively pristine. Patterns of rainfall were studied of tusk fractures amongst these populations to correct for any effect that acquired tusklessness may have on our predictions. The incidence of tusk fractures was related to annual rainfall, but the mechanism that leads to an increase of the condition in drier areas was not clear Incidences of tusk fractures in free-ranging populations implied that the frequency of acquired bilateral tusklessness is low and should not affect our results. All males had tusks. Tusklessness in females was high in the small skewed founder population and some of those where there was a history of poaching. The incidence is expected to decline if the residual population is large.