Search

Oestrus ovis (Linnaeus 1761) is a parasite of sheep and goats, in which the fly larvae are obligatory parasites of nasal and sinus cavities. Oestrosis is endemic in hot and dry regions, especially in Mediterranean areas of Europe, Africa and America. Infected animals firstly suffer from fly strike, when adult flies inject first stage larvae on their nostrils and secondly, hosts will suffer from nasal-sinus myiasis with varying clinical respiratory signs. The disturbance caused to small ruminants while grazing and the effects during development of larvae can have severe consequences on livestock production. The evolution of O. ovis depends on the weather; the parasite is very well-adapted to their environment, being able to undergo hypobiosis either inside or outside the host, according to the climatic environmental conditions and seasonality. Understanding the epidemiology and life cycle of O. ovis is crucial to design effective control measures of this myiasis. Moreover, O. ovis infestation is considered a zoonosis; it causes ophthalmomyiasis in man in many parts of the world. The present article focuses on describing the main information about this parasite gathered in the last 20 years.

Vaccination programs against Ovine Respiratory Complex (ORC) in lambs should be accompanied by non-specific preventive measure, e.g., establishment of proper management and husbandry conditions. Implementing a vaccination plan against ORC requires: involvement of all farm staff, recording data, a positive cost:benefit analysis and continuous monitoring over time. Licensed vaccines for sheep are only against Mannheimia haemolytica (MH), Bibersteinia trehalosi (BT) and Pasteurella multocida (PM). According to the antigens contained in the MH vaccines, these can be divided into outer membrane protein vaccines (OmpA), leucotoxoid vaccines (LKT) and iron regulated protein vaccines (IROMP). Each serotype of MH or BT presents differences in these three antigens, although in the case of IROMP, there is an effective cross protection among them. In addition, strains of bovine origin do not protect sheep and vice versa. For PM, vaccines containing bacteria grown in iron restricted conditions give better results. The lambs should be vaccinated during the first week of life followed by a booster dose three weeks apart. The best results are obtained with LKT vaccines, when the serotype that is present in the farm is included in the vaccine, or with IROMP, which can be applied in any situation.

'Numerous disorders affect the lower respiratory tract of adult sheep, including Maedi Visna, ovine pulmonary adenocarcinoma and verminous pneumonias as reported elsewhere in this special issue. Herein we examine gangrenous pneumonia, ovine respiratory complex (ORC) and the visceral form of caseous lymphadenitis (CLA). Gangrenous pneumonia is a pulmonary infection commonly caused by inhalation of foreign materials, producing inflammation and necrosis of the lung parenchyma. ORC is a complex disease process involving a range of host-pathogen-environment interactions, where host immunological and physiological mechanisms interact with multiple etiological agents including bacteria, plus environmental factors or stressors. Visceral form of CLA commonly causes lesions in mediastinal lymph nodes and lung parenchyma, producing respiratory clinical signs, particularly the coughing that is responsible for transmission of the disease by aerosol. The economic relevance, etiological, clinical and pathological findings of these diseases are reviewed.

The aim of the present study was to investigate the clinical, pathological and immunological changes in lambs infected experimentally with Salmonella enterica subsp. diarizonae serotype 61:k:1,5,(7) (SED) that causes chronic proliferative rhinitis (CPR) in sheep. Eleven four-month-old lambs were infected with 3.2 × 10 8 UFC of SED by nasal route and four lambs with the same age were kept as placebo group. Clinical explorations were carried out monthly and vaginal, nasal swaps and fecal samples were taken for microbiological study during one year. Furthermore, a postmortem investigation was performed. Ventral turbinates of both nostrils and submandibular, parotid and retropharyngeal lymph nodes were sampled for histopathological, immunohistochemical and microbiological studies. Cell mediated immune response was assessed by lymphocyte stimulation test (Con A, PWM, PHA and LPS were used as mitogens), DTH test and by measuring IFN-γ concentration in serum and cultured supernatants. SED was isolated from nasal swabs and fecal samples of all infected lambs virtually throughout the study. No isolations were obtained from control group. At necropsy, no lesions associated with SED were recorded; however, the microorganism was isolated in regional lymph nodes in all infected animals. Moreover, infected lambs showed lower stimulation indices to Con A, PHA and PWM and higher for both LPS ( P 0.001). Besides, DTH response was lower in infected lambs than in the control group, but statistical significant differences were not found ( P > 0.05). Serum levels of IFN-γ during the experiment were higher in infected sheep than in the control group, suggesting an active infection. Furthermore, mitogens stimulated the production of IFN-γ in lymphocyte cultures from infected sheep, and the highest level were obtained with Con A. These results demonstrate that after experimental infection of healthy lambs with S. enterica subsp . diarizonae serotype 61:k:1,5,(7) infection was maintained for at least one year in the upper respiratory tract and that digestive route should be taken into account as a possible way of SED elimination. Moreover, SED infection caused a weak response of the T cells; nevertheless, more studies are needed to understand the mechanisms involved in the immunitary response and pathology of CPR in sheep associated with Salmonella enterica subsp. diarizonae infection.

Veterinary undergraduates, after completion of five academic years, need to have developed a set of skills for working as veterinary practitioners. Sheep as an educational model in veterinary pathology offers to students the opportunity to study with an easily handled animal species, which shows various diseases. In the present model, sheep are treated as individual patients; a thorough individual examination is made with all laboratory tests that are considered necessary. Undergraduates can study main sheep diseases, but also disorders occurring less often and carry out an individual animal investigation as it is normally done in companion animals. Final diagnosis is confirmed by pathological examination, so they can check if there is agreement or disagreement between clinical and pathological diagnosis. The opinion of students about this teaching model was obtained from a questionnaire and it provided an encouraging and valuable information and feedback. Moreover, information collected from monitoring, clinical examination and pathological examination of animals is directly transferred to the farmers and this has obvious benefits in terms of flock health management and disease surveillance.

Hypospadias are the most frequent human penile abnormality. They have a genetic basis, even if environmental factors such as low birth weight, and exposure to hormones and to endocrine disruptors during pregnancy are not totally discarded. In sheep, the variable incidence in different breeds and a coincident occurrence in a couple of twins have suggested a possible genetic origin. We are presenting a detailed study of hypospadia in two rams. In both cases, high inbreeding supports a genetic origin for this pathology. A preliminary analysis on the second exon of the 5α-reductase 2 did not provide evidences for mutations in these individuals, even if they are often responsible for hypospadias in humans.

Pneumonia is responsible for important economical losses in the sheep industry in Spain and many other sheep-rearing countries, being the main cause of lamb death, and of losses due to condemnations in abattoirs and of drug costs. This respiratory syndrome is a complex disease involving the relationship between host and environment. The present study analyses the influence of environmental factors on the development of pneumonia in lambs. Statistically significant correlations were found between pneumonia as a cause of lamb death and climatic factors such as rainfall, humidity and intensity and direction of wind. The type of farm building was also an important factor to take into account in order to improve the prevention of pneumonia in lambs. Moreover, the age of the lambs was seen to be a significant item in the study of pneumonia. Respiratory pathology increased from 23 days of age. This fact permits the implementation of measures from birth to 23 days with a view to reducing pneumonia and its negative influence on lamb production. The paper discusses the practical implications of these findings for sheep production.

A sheep farm situated in the north-east of Spain suffered an outbreak of polyarthritis in lambs from May 2006 until September 2007. The percentage of affected animals at the beginning of the outbreak was 5.71%. This percentage decreased to 1.42% by September 2007. Samples of joint fluid were colleted for culture, and antibiotic susceptibility testing was performed. Streptococcus dysgalactiae was isolated in microbial culture and the testing revealed resistance to tetracycline, a commonly used antibiotic in the treatment of arthritis in sheep. Affected lambs were treated with parenteral lincomycin and dexamethasone with satisfactory results. Nasal, auricular and vaginal samples were collected from 30 ewes in order to evaluate these locations as a reservoir for the bacteria in sheep. No isolation of S. dysgalactiae was obtained from these areas. S. dysgalactiae is also considered an environmental cause of clinical and subclinical mastitis in sheep. Milk samples from 95 affected ewes were collected during the same period of time (20 suffering from clinical mastitis and 75 subclinical mastitis, after performing California Mastitis Test on 400 milking ewes). S. dysgalactiae was isolated in pure culture from the milk sample of one ewe, the mother of a polyarthritic lamb. S. dysgalactiae has been reported as a cause of polyarthritis in calves and goats and it should be considered as a relevant cause of polyarthritis in lambs, the digestive tract being, probably, the main pathway of infection.

This paper reports a case of vagus nerve damage in a ewe due to the presence of a mineralized Cysticercus tenuicollis cyst in the omentum, adjacent to the reticulum and over the ventral branch of the nerve. The clinical course, surgical management and post-mortem findings of vagus indigestion are described. For the author's knowledge this is the first description of this syndrome in sheep.

This communication reports the possibility of clinical diagnosis of caseous lymphadenitis in sheep, using data obtained from clinical history, examination, haematological and biochemical analysis, ultrasonography and, finally, isolation of Corynebacterium pseudotuberculosis in affected ewe urine culture. To the author's knowledge this is the first description of an isolation of C. pseudotuberculosis in urine culture of a CLA affected animal and it could help to detect subclinically affected animals.