Culex annulirostris as a vector of Eperythrozoon ovis infection in sheep

Eperythrozoon ovis, a blood parasite of sheep, was transmitted from carrier lambs to susceptible lambs by the interrupted feeding of the mosquito Culex annulirostris. The circumstances of some of the transmissions were similar to those encountered in the field, in that carrier and susceptible lambs were exposed to a natural population of mosquitoes, while in another transmission an artificial means of containment of the mosquitoes was used. Infective E. ovis organisms were shown to be present in and/or on Cx. annulirostris for at least 14 hours by the inoculation of physiological saline-extracted material from macerated mosquitoes fed on E. ovis carrier lambs.     

Effect of Eperythrozoon ovis infection on the reductive potential of sheep erythrocytes

Reduced glutathione (GSH) and methaemoglobin were measured in sheep blood during an infection cycle of Eperythrozoon ovis and in uninfected control blood. The GSH levels in infected erythrocytes were significantly lower in the latter half of the infection cycle. Incubation with acetylphenylhydrazine (APH) resulted in negligible leves in infected cells whereas control cells were approximately 45% normal. Infection with E. ovis had little effect on methaemoglobin levels. However, incubation with APH caused a marked increased of the methaemoglobin levels in both infected and control blood; the control methaemoglobin levels were significantly higher.It was concluded from these observations that E. ovis interfered with maintenance of GSH within erythrocytes to an extent that when challenged with an oxidizing chemical erythrocyte membrane integrity could be lost. In addition E. ovis may bave provided some protection against oxidative damage for the heme portion of the haemoglobin molecule or the amount of oxidative damage to haemoglobin was further advanced in the infected cells.     

A prediction model for strike in the sheep nasal fly, Oestrus ovis, in Namibia

A model was developed for predicting outbreaks of Oestrus ovis throughout the main sheep farming areas of Namibia. Pupal developmental periods were studied, concomitant air and soil temperatures enabling degree-day calculations to be made for prediction of adult fly strike. Monitoring of larval infection established seasonal incidence of O. ovis infestation and acted as verification of predictions. The establishment of relevant isothermal maps for Namibia made possible extrapolation from the several study sites to the entire sheep farming area. Retrospective and actual predictions of the important first peak after winter were considered accurate enough to recommend timing of control measures. No evidence of overwintering of first stage instars was found, the strategy used instead being extended pupation. Adult fly energy reserves were determined.     

Larval salivary gland proteins of the sheep nasal bot fly, (Oestrus ovis L.), are major immunogens in infested sheep

Tissue extracts from larval instars of the sheep nasal bot, Oestrus ovis, were resolved by gel electrophoresis under both native and denaturing conditions. Polypeptides resolved under these conditions were tested by immunoblotting against sera of infested sheep. Of all tissues examined in this study, salivary glands proved to be major immunogens in infested sheep. Salivary gland polypeptides were also detected in the washing solution as larval secretory products (LSP). To a minor extent, a few polypeptides from the larval cuticle were also found to be immunogenic, but they did not contribute to LSP. These results were further corroborated by nasal infestation of rabbits that also developed specific antibodies against larval salivary gland polypeptides from Oestrus ovis.     

Simulation analysis of the population dynamics of the mite, Psoroptes ovis, infesting sheep.

The pattern of population growth of the ectoparasitic mite, Psoroptes ovis (Acari: Psoroptidae), on its ovine host is considered through the development of a Leslie matrix-based, simulation model. The model is parameterised using experimental data in conjunction with reanalysis of published data. The model shows that on sheep P. ovis populations grow at a rate of approximately 11% per day and the population doubles every 6.3 days. Additional rates of adult mortality, in excess of 50% per day, need to be imposed to prevent population growth. The predictions of the model are tested by comparison of the expected numbers of mites with the numbers recorded in lesions either on naturally infested sheep where the date of infestation can be estimated or on one artificially infested animal, where the initial number of mites and date of infestation are known precisely. In both cases the observed number of mites in lesions relate closely to the numbers expected from the simulations. The model simulations do not support the concept of a 'lag' phase as distinct from the 'growth' phase in the changing pattern of mite abundance on an infested sheep and suggests that the observed pattern of growth is a natural function of an exponential increase in numbers. The development of such models and their use in explaining the demographic processes which drive mite population dynamics are discussed.     

The protection of lambs from eperythrozoon infection while suckling Eperythrozoon ovis carrier ewes

When lambs born to and suckling Eperythrozoon ovis carrier ewes were inoculated with heparinised blood containing large numbers of E. ovis organisms, the lambs were either sterilised of the infection or patent infection was suppressed till the lambs were weaned. In vitro infection, transplacental transfer of antibodies or soluble antigens could not be demonstrated.     

Radiographic techniques of the nasal cavity and sinuses

Diseases of the nasal cavity and sinuses can be frustrating problems for owners and veterinarians alike. Initial physical examination and routine blood work are often unrewarding in directing the clinician at a diagnosis. Diagnostic imaging can help characterize the disease process and direct treatment or further diagnostics. Radiographs of the skull are an excellent first-line diagnostic step in the analysis of nasal disease. The following article reviews basic techniques, positioning, and interpretation of radiographs of the nasal cavity and paranasal sinuses.     

Distribution and population dynamics of ticks (Acari: Ixodidae) infesting sheep in Sennar State, Sudan

A cross-sectional survey of ticks infesting sheep was conducted in Sennar State, Sudan. A total body collection of ticks was carried out at five localities Sennar town, Singa, Dinder, Abu Naama and Um Banein on two types of Desert sheep (Watish and Ashgar) on two farms at each locality at two monthly intervals for one year starting July 2002 to May 2003. Four tick genera and eight species were identified. They were Amblyomma lepidum, Hyalomma anatolicum anatolicum, Hyalomma truncatum, Rhipicephalus (Boophilus) decoloratus, Rhipicephalus camicasi, Rhipicephalus evertsi evertsi, Rhipicephalus guilhoni and Rhipicephalus muhsamae. A significant (P < or = 0.05) seasonal pattern of activity was observed for A. lepidum and R. guilhoni with peak activity occurring during rainy seasons. The highest mean number of ticks (7.26 +/- 0.58) was recorded at Abu Naama, while the lowest mean (3.61 +/- 0.31) was recorded in Sennar. Watish type sheep carried significantly (P < or = 0.05) more ticks than Ashgar type.     

Clotrimazole and enilconazole distribution within the frontal sinuses and nasal cavity of nine dogs with sinonasal aspergillosis

Objectives: Multiple topical treatments are often required for clinical cure of mycotic rhinosinusitis in dogs. The objective of this study was to describe the distribution and retention of enilconazole and clotrimazole solutions using a temporary trephination protocol. Methods: Nine client-owned dogs diagnosed with mycotic rhinosinusitis between March 2008 and December 2009 were prospectively enrolled and were sequentially allocated to receive treatment with either clotrimazole (1% in polyethylene glycol) or enilconazole (10% solution), after imaging and rhinoscopic assessment. Both frontal sinuses were trephined, debrided and flushed with saline. Infusion was administered via frontal sinuses with dogs in sternal recumbency and computed tomography (CT) performed 5 minutes after completion. Distribution was scored 1 to 4 at the canine tooth, premolar 4, cribriform plate and frontal sinus on both sides, for a maximum score of 32. Results: Distribution of antifungal agents to all regions of the nasal cavity and frontal sinuses was achievable, but varied considerably. Retention was poor in 10 of 18 regions assessed. Clinical Significance: Distribution of antifungal agents within the frontal sinuses is achievable using temporary trephination; however, distribution is variable and retention is often poor.     

Surgical anatomy of the nasal and paranasal sinuses in Egyptian native sheep (Ovis aries) using computed tomography and cross sectioning

The present work aimed to describe the normal computed tomography (CT) and cross‐sectional anatomy of the nasal and paranasal sinuses in sheep and to correlate these features with the relevant clinical practices. Twenty apparent healthy heads of Egyptian native breed of sheep (Baladi sheep) of both sexes were used for studying these sinuses. CT images and their closely identical cross sections of the same head were selected and serially labelled in a progression from the rostral nasal region to the caudal aspect of the head using cheek teeth as landmarks. The current investigation reported seven sinuses in sheep, including maxillary, frontal, lacrimal and sphenoidal as paranasal, as well as dorsal and middle conchal and ethmoidal as nasal with unnoticeable palatine and ventral nasal conchal sinuses. The boundaries, extension, structure and communications of these sinuses were fully described. The current study provided anatomical guidelines for surgical interference in the frontal and maxillary sinuses during trephination, dehorning and sinuscopy. Also, an acceptable anatomical explanation was reported in this study for the high incidence of maxillary sinusitis than other sinuses. CT and cross‐sectional anatomy could be used as helpful database for diagnosis and clinical interference of the nasal and paranasal sinuses in sheep.     

The effect of Sarcocystis tenella on wool growth in sheep

A dose of 1 × 10⁴Sarcocystis tenella sporocysts produced significant depression of wool growth in lambs dosed at 1 month of age. No significant effect on wool growth was produced when lambs were dosed at 5 months of age.     

Epidemiology and seasonal dynamics of gastrointestinal nematode infections of sheep in a semi-arid region of eastern Ethiopia

A study on the epidemiology and seasonal dynamics of gastrointestinal nematode infections of sheep was carried out in a semi-arid region of eastern Ethiopia for 2.5 years (May 2003 to September 2005). The experimental flock comprised a total of 60 Black Head Ogaden sheep, consisting of four equal groups of young male and female and old male and female sheep. These grazed on communal pastures together with a larger university flock, as well as with animals owned by neighbouring small-holder farmers. A new experimental flock was established each year of the study. Parasitological data (EPG, faecal culture L3, PCV and FAMACHA estimates) and animal performance (weight change) were recorded each month on all experimental animals. In addition, four tracer lambs were assigned each month to the flock to determine the seasonal patterns of infective larvae acquired from pasture. Results showed distinct seasonal patterns associated with the bi-modal annual rainfall. High levels of infection occurred during the short and long rain seasons with peaks occurring in May and September of each year. Haemonchus contortus was the most prevalent parasite, followed by Trichostrongylus spp., with a number of other nematode species being occasionally recorded. H. contortus showed and increased propensity to undergo arrested development during the dry seasons. Correlations between EPG and PCV, EPG and FAMACHA eye scores, and PCV and FAMACHA eye scores were all highly significant (P<0.001). However, there was no significant association between the EPG and LW of the study animals during each study year. This information will provide a basis for developing epidemiologically based control strategies for gastrointestinal nematode parasites that are appropriate for flocks owned by small-holder farmers of semi-arid areas of eastern Ethiopia.     

Phylogentic analysis of Anaplasma ovis strains isolated from sheep and goats using groEL and mps4 genes

Evidence of Anaplasma spp. in goats and sheep in Cyprus has been demonstrated by previous research. Herein, further research was performed for the identification of the exact Anaplasma spp. resulting in the identification of Anaplasma ovis strains in all samples examined. We used a bioinformatics as well as a molecular approach (study of groEl and mps4 genes) in order to verify the validity of the results. All samples depicted the presence of A. ovis regardless of the host (goat or sheep).     

The recovery of Bordetella bronchiseptica strains by means of smears from the nasal cavities of pigs

The paper presents results obtained from a study on the recovery of Bordetella bronchiseptica strains from the nasal cavities of pigs by means of tampon smears. There are several important factors influencing the reliability of recovery: restraining of animals, thorough disinfection of the snout about the nostrils prior to the taking of samples, correct method of sample collection using suitable tampons, suitable culture media for cultivation, correct cultivation method and diagnostic procedure for the isolation and identification of grown cultures.