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Treatment of bovine mastitis depends on the cause, the clinical manifestation and the antibiotic susceptibility of the agent. Mastitis therapy is commonly unsuccessful owing to pathological changes that occur in the udder parenchyma as a result of the inflammatory reaction to mastitogenic bacteria, pharmacokinetic properties of antimicrobial mastitis drugs, mastitogenic bacterial and related factors, and poor animal husbandry and veterinary interventions.

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Not all parameters are trustworthy and practical to use as parameters to determine heat stress in dairy cattle. The temperature-humidity index (THI) is still the best, simplest and most practical index (parameter) for measurement of environmental warmth which cause heat stress in dairy cattle. It is practical, easy to determine and relatively trustworthy to use body temperature and respiratory rate as parameters to determine heat stress in dairy cattle. These physiological parameters must always be used together with THI values to determine and evaluate heat stress in dairy cattle. For practical purposes, plasma cortisol concentration and milk composition cannot be used as parameters to determine heat stress in dairy cattle although good indications of acute or chronic heat stress can be obtained. Vanillic acid is a break-down product of adrenalin found in milk, but before its concentration in milk can be used as an indicator/parameter of heat stress in dairy cows, more about the pharmacodynamics of adrenaline in the milk has to be known. Selection and breeding of dairy cows on the basis of their adaptibility to heat stress using the most practical heat stress parameters will ensure that their offspring will have superior performance in the prevailing environmental conditions.

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Regression models are proposed for predicting conception rate in a dairy herd under South African and especially Natal conditions. Conception rate (CR%) was related to mean monthly temperature-humidity index (THI) by curvilinear regression equation model; CR% = 812.7 +/- 28.61 THI - 0.2322THI2 (P = 0.061), and by linear regression equation model; CR% = 188.0 - 1.906THI (P = 0.023). Conception rate was related to numerical month of the year (M) by: CR% = 44.34 + 6.168M - 0.428M2 (P = 0.106). Further investigations to test the proposed regression models under various dairy-herd conditions and to improve reproduction in South African dairy herds are needed.

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Since August 1993 moderate to serious respiratory problems with necrotic pneumonia, growth depression and fast increasing mortality are seen in commercial turkeys (2-8 weeks of age) and broilers (4-6 weeks of age). An unidentified pleiomorphic Gram-negative rod was isolated from affected tissues. This Pasteurella-like organism, with yet unknown taxonomy, is recently named Ornithobacterium rhinotracheale gen. nov. sp. nov. or 'Taxon 28'. Experimentally severe growth depression and arthritis could be evoked in commercial turkeys and chickens. Respiratory signs caused by O. rhinotracheale could not (yet) be reproduced experimentally. This is the first report of the isolation of this organism in poultry in the Netherlands findings.

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Two cases of solitary plasmacytoma of the skull are presented. Both patients underwent surgery, and the tumors were removed completely. The patients did not receive postoperative radiotherapy. After a follow-up period of 18 months, neither patients had a local recurrence, but one developed disseminated systemic myeloma.

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Three regression models are proposed for predicting reproduction in a model dairy herd under South African conditions. Conception rate (CR%) was related to mean monthly temperature-humidity index (THI) by; CR% = 31.15 THI - 0.25 THI(2) - 890.2, and first service conception rate (FSCR%) to THI by; FSCR% = 173.45 - 1.79 THI. Conception rate was related to numerical month of the year (M) by; CR% = 11.86 M - 0.82 M(2) + 26.36. The relation between mean monthly THI values and the conception rate of dairy cattle is significant. Further investigations to test the proposed regression models under various dairy herd conditions and to improve reproduction in South African dairy herds are needed.

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Temperature-humidity index (THI) values applicable to South Africa and Namibia have been established during this investigation for each month of the year by means of computerized modelling and mapping techniques. The data indicate that each year heat stress risk areas (HSRA's) expand from August to January and retract from February to July. The THI values classified according to the Livestock Weather Safety Index (LWSI) for lactating dairy cattle (LDC), suggest that, especially during November to March there is the risk of moderate to advanced heat stress in most South African dairy cows. This has important implications for their general health, udder health, production and reproduction. Careful planning of facilities and highly adaptable herd management are required to protect dairy cattle from heat stress.

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November-March are the hottest months of the year with the highest monthly mean "temperature-humidity index" (THI) in South Africa and Namibia. These 5 months are associated with severe heat stress in dairy cattle, are of critical importance for their performance and may have great economic implications for the owner as well as for the dairy industry. Firstly, compared with the existing Livestock Weather Safety index (LWSI), more relevant meteorological data can be generated when mapping South Africa and Namibia according to the LWSI modified for lactating dairy cattle (LDC). Secondly, compared with the observed true THI values alone, more relevant data on heat stress and its deleterious effects on dairy cattle performance, become available when mapping South Africa and Namibia according to the combined observed true and predicted THI values. Minimum precautions against heat stress in dairy cattle are recommended depending on THI values as classified by the LWSI for LDC.

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The Livestock Weather Safety Index (LWSI) indicates that in large areas of South Africa and South West Africa/Namibia and for prolonged periods of the year warm conditions are causing heat stress in food-producing animals, especially dairy cattle, thereby hampering their performance. South Africa and South West Africa/Namibia have been mapped according to a modified LWSI, which includes the critical "temperature-humidity index" value for milk production. The importance of heat stress in dairy cattle is discussed relative to such areas.

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An extremely pleomorphic virus was isolated from broilers with swollen head syndrome. This virus seems to be related to the virus causing turkey rhinotracheitis.

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Routine bacteriological diagnosis of bovine mastitis does not provide an index to the obligate anaerobic flora involved. No anaerobic bacteria were recovered from cows with normal quarters or those with latent facultative anaerobic or aerobic udder infections as diagnosed according to the criteria of the International Dairy Federation. Simultaneous isolation of anaerobic bacteria from udder quarter abscesses and mastitic milk from the same quarter occur in some lactating dairy cows. In most dairy herds there are cows with anaerobic udder infections. Anaerobic bacteria have been isolated from lactating as well as from dry cows. Most anaerobic bacteria were isolated concurrently with facultative anaerobic bacteria except in aseptic mastitis cases. The polymicrobial nature of udder infections shows that multiple anaerobic as well as facultative anaerobic species colonise and act together. In spite of antibiotic therapy, anaerobic bacteria were still isolated from mastitic quarters. Gram-positive anaerobic bacteria were mostly sensitive to penicillin-G but most of the Gram-negative anaerobic bacteria were resistant and some Bacteroides fragilis strains produced beta-lactamase. Nearly all the aminoglycosides display consistently poor activity against anaerobic bacteria. A high degree of resistance against tetracyclines was also demonstrated. Anaerobic Gram-positive cocci and rods were sensitive to common antibiotics. The pathogenicity of several pure cultures of anaerobic bacteria has been demonstrated by their ability to induce clinical mastitis in healthy lactating udders. Anaerobic bacteria may act as mastitis pathogens probably in a primary and/or secondary role because clinical mastitis could be induced in normal quarters under experimental conditions. Their high prevalence of anaerobic bacteria in mastitic quarters and the ability of some strains to produce heparinase also suggests a pathogenic role. The handling of udder abscesses and the therapy of mastitis where anaerobic bacteria may be involved, is fully discussed.

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In March 1978, a number of turkeys with severe respiratory symptoms affecting over 80% of the flock were investigated for a possible causative agent. With the standard techniques used for the isolation of bacteriae, mycoplasmae and viruses, only Mycoplasma gallisepticum, Mycoplasma meleagridis and Newcastle disease virus were isolated. Tracheal organ cultures were subsequently prepared from 27-day-old turkey embryos and inoculated with sinus exudate from affected turkeys. After an incubation period of 4 days a virus was isolated with which the typical symptoms, as observed in the field, could be reproduced in susceptible turkeys after 3-5 days. Following primary isolation in tracheal organ cultures, the virus grew readily in embryonated eggs and Vero cells. With the electron microscope, virus-like particles, varying in size from 40 nm-500 nm, were observed, having a pleomorphic shape and studded with fine surface projections. The virus seems to fall into the family Paramyxoviridae. A vaccine produced from attenuated virus in embryonated eggs afforded good protection against mortalities due to airsacculitis that normally follows on to turkey rhinotracheitis infection. The serological and clinical effects of the virus on chickens are also reported on.

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Various forms of clinical and subclinical mastitis occur in the bovine, and intramammary therapy alone or in combination with parenteral therapy must be implemented with due consideration of udder pathology and the pharmacokinetic properties of drugs used for the treatment of mastitis. Supportive therapy for cows with acute or peracute mastitis and optimal animal husbandry are of the utmost importance for a relatively good prognosis. The withholding period of milk for human consumption after the last intramammary antibiotic treatment as well as minimum intervals between antibiotic dry cow treatment and calving are given. The main reasons for mastitis therapy failure are udder pathology caused by the inflammatory process, the pharmacokinetic properties of mastitis drugs under those conditions, inadequate supportive therapy and poor animal husbandry.

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Teat canal infection (TCI) or colonization, subclinical mastitis (SCM) cases and other forms of intramammary infections (IMI) may persist despite regular post-milking teat disinfection. Spontaneous healing of TCI can occur and this points to the dynamic state of the reactions of TCI etc. Disinfecting teat dipping does not necessarily prevent new TCI and IMI. Teat dipping may, however, be applied with good effect in the prevention of new udder and teat canal infections. Several factors predispose to TCI e.g. poor management, hygiene and animal husbandry.

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A general introduction detailing background information concerning the term "disaster" is presented. A discussion of pertinent legal guidelines and an overview of the possible role of the veterinarian, firstly as a paramedical assistant and secondly as a veterinary public health official, is presented.

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The International Dairy Federation's (IDF) criteria for classification of subclinical bovine health conditions does not provide a true picture of the health status of the udder. When combining these criteria with the serum albumin levels of milk samples, the IDF's classification of sub-clinical mastitis could be extended to include 8 possible conditions such as normal quarters, septic mastitis, aseptic mastitis, relevant and irrelevant teat canal infection, specific and unspecific hyperalbumingalactia and unspecific cellular reaction. When the bacteriological results of teat canal swab samples were combined with the IDF's standards, these conditions could be scaled down to 4 diagnoses which included normal quarters, aseptic mastitis, teat canal infections, subclinical mastitis and a combination of the latter 2 conditions. When applying the teat canal swabbing technique, up to 16% of quarters classified as normal and 10% as cases of aseptic mastitis according to the IDF's criteria in fact, have TCI. Since classification of the health status of quarters according to the IDF's criteria and with due regard to the bovine serum albumin values of milk, did not include the bacteriological results of the teat canal swab samples, further research must be done to clarify the existence of conditions in the IDF classification. Teat canal infections may result in damage to the udder parenchyma as manifested by the elevated bovine serum albumin content of milk.

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The diagnostic reliability of techniques for determining the prevalence of teat canal infections varies: bacteriological results obtained by examination of teat canal swabs were 20% higher on average than those of foremilk samples (FMS) examined and classified according to the criteria of the International Dairy Federation (IDF). Since they are based exclusively on the bacterio-cytological results of the FMS, the IDF criteria for the classification of the various forms of subclinical udder conditions do not permit an accurate classification of the health status of the udder.

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The specific therapy of bacterial colonization of the teat canals of dried-off dairy cows by means of small amounts (33 mg/0.25 ml and 14 mg/0.1 ml) of a procain benzyl penicillin-dihydrostreptomycin sulphate combination has been investigated. Of 36 teat canals treated with 0.25 ml antibiotic preparation each, 24 (66.6%) were infected at the beginning of the dry period, whereas at its termination only 7 (19.4%) showed bacteriologically positive swab cultures. By treating a further 43 quarters with 0.1 ml quantities of an antibiotic preparation each, the prevalence of infection dropped from 32.5% to 14%. Untreated controls (20 quarters) showed no significant change. Cultures of teat canal swabs were generally twice as sensitive for indicating the presence of bacteria compared to foremilk sample cultures. Staphylococcus aureus was the most commonly isolated organism, followed by Streptococcus agalactiae, Corynebacterium bovis and Staphylococcus epidermidis.

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A variety of non-sporulating anaerobic bacterial species were isolated from udder abscesses in 10 lactating dairy cows. Fifty percent of the abscesses yielded multiple anaerobic species and the other 50% only 1 species. The anaerobic bacteria, however, were always accompanied by classical facultative anaerobic mastitogenic bacteria. In four of the five cows also afflicted with mastitis in the quarters with abscesses, the anaerobic and facultative anaerobic bacteria were identical. Peptococcus indolicus was the most commonly isolated organism followed by Eubacterium and Bacteroides spp. Bacteroides fragilis was resistant to penicillin, ampicillin and tetracycline.

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Three healthy lactating quarters of a Friesland cow were each experimentally infected with a pure culture of a strain of either Bacteroides fragilis, Eubacterium lentum or a Peptostreptococcus sp. respectively. The onset and progression to clinical mastitis was monitored 12 hourly by examination for clinical signs of inflammation, bacterial culture, somatic cell counts and with a strip cup. All infected quarters developed clinical mastitis within 24 hours. The 2 quarters infected with B. fragilis and E. lentum respectively were treated 4 times consecutively at 12 hour intervals, commencing at 24 h by intramammary instillation of 10 ml of a mixture containing 200 mg lincomycin hydrochloride, 200 mg neomycin sulphate and 5 mg methylprednisolone (Lincocin Forte, Upjohn). Both quarters became clinically normal and no bacteria could be detected in the secretions 12 hours after the first treatment. At 36 hours the strip cup became negative, and the somatic cell count dropped to less than 500 X 10(3) at 72 hours after the initial treatment. The quarter infected with a Peptostreptococcus sp. was unable to overcome the infection by natural means when intramammary treatment was delayed for the first 36 hours after the onset of clinical mastitis. Subsequent treatment of this quarter gave results similar to those treated earlier.

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