Equine immunology 4: vaccines and antisera.

This paper attempts to relate the practicalities of vaccine development to the ideals which should be aimed for in a new vaccine. The type of immune response induced is dependent upon the nature of the antigen in the vaccine and the site and timing of its presentation to the immune system. In this respect the influence of age, maternal immunity and antigenic competition are discussed. The possible side effects associated with vaccination are defined and vaccines which are currently available for horses are reviewed. These vaccines are mostly for the prevention of respiratory disease. Finally, the possible uses for antisera are considered.

Equine immunology 3: immunopharmacology--anti-inflammatory and antihypersensitivity drugs.

This article reviews anti-inflammatory and antihypersensitivity drugs under these 4 headings: Functional or physiological antagonists; Selective pharmacological inhibitors; Broad spectrum anti-inflammatory drugs; Miscellaneous inhibitors. The compounds considered include sympathomimetic amines, anticholinergic drugs, antihistamine drugs, tryptamine antagonists and dopamine antagonists, glucocorticosteroids and non-steroidal anti-inflammatory drugs, disodium cromoglycate and diethylcarbamazine citrate. The relationship of the pharmacological actions of these compounds is considered in the context of clinical conditions. The potential for immunomodulatory pharmacology is discussed using levamisole as an example.

Equine immunology 2: immunopharmacology--biochemical basis of hypersensitivity.

In general, 4 types of hypersensitivity reactions can be defined according to their immunological basis and clinical appearance. The differing mechanisms of these responses are described with particular reference to chemical mediators which through their pharmacological actions contribute to the clinical manifestations of hypersensitivity. Chemical mediators may exert their influence locally or systemically through their action on effector, tissues or organs and in addition, may be involved in the recruitment of cells of specific type to the site of the reaction. The possible role of these mediators in hypersensitivity in the equine species is discussed to provide a background for a subsequent paper which will be concerned with the therapy of hypersensitivity conditions.

Equine immunology: an introductory review.

This article attempts to relate some of the more recently accepted concepts of immunology to an understanding of the mechanisms of immunity in the horse. The cellular mechanisms involved in the immune response are outlined, with an indication of their likely role in humoral and cell-mediated immunity. In describing the humoral immune response, the structure and function of the different equine immunoglobulins are reviewed. The significance of humoral and cell-mediated immune responses are considered in relation to actively and passively acquired immunity.

Studies on the efficacy of fenbendazole used in a divided dosage regime against strongyle infections in ponies.

The efficacy of a fenbendazole divided dose regime against immature stages of Trichonema spp, Strongylus vulgaris and Strongylus edentatus was evaluated. A group of 8 naturally infected 30 to 36-month-old ponies was divided into 2 equal groups on the basis of previous treatment and faecal egg counts, one group being treated with 7.5 mg/kg bwt of fenbendazole daily for 5 days. This treatment regime removed 80 per cent of migrating S vulgaris larvae, 100 per cent of migrating S edentatus larvae and 95 per cent of the mucosal stages of Trichonema spp. In addition, a virtual 100 per cent elimination of adult stages of large and small strongyles was obtained.

The effect of a preparturient fenbendazole treatment on lactation yield in dairy cows.

Studies carried out on nine farms in north-west England indicated that fenbendazole treatment of adult winter calving dairy cows in the dry period caused an overall increase of 173 kg in their subsequent lactation yield. There was some evidence to suggest that a correlation existed between pasture Ostertagia ostertagi larval burdens and subsequent serum pepsinogen and milk yield responses post treatment. Marked interherd and regional differences existed in the milk yield response to anthelmintic treatment and possible reasons for such results are discussed.

Studies on the faecal egg output of horses after treatment with fenbendazole.

Examination of faecal egg counts in horses and ponies has shown that after treatment with fenbendazole at dose levels of 7.5, 45 and 60 mg/kg, faeces remained free from strongyle eggs for periods of 6 to 18 weeks. The significance of these results is discussed in relation to routine anthelmintic treatment of horses. In particular, the activity of fenbendazole against mucosal stages of strongyle parasites allows for treatment to be recommended at less frequent intervals than when using other anthelmintics.

The efficacy of fenbendazole in the control of immature strongyle infections in ponies.

The efficacy of fenbendazole against immature stages of Trichonema spp., Strongylus vulgaris and Strongylus edentatus was evaluated. Naturally infected 6 to 12 month old ponies were given single, oral doses of 0, 15, 30 and 60 mg/kg of body weight. A dose response relationship was noted between increasing dose levels and efficiency against larval trichonemes and migrating stages of S. vulgaris and S. edentatus. Dose levels of 30 mg/kg and higher removed 93 per cent of mucosal stages of Trichonema spp., while doses of 60 mg/kg removed 83 per cent and 89 per cent of the migrating larvae of S. vulgaris and S. edentatus respectively.

Prophylactic use of hyperimmune serum in experimental colisepticaemia in calves.

Evidence is presented to demonstrate the efficacy of an intravenously administered polyvalent hyperimmune serum prepared from bovine serum, in the prevention of experimental colisepticaemia produced by oral challenge with E coli O78: K80(B) in colostrum deprived calves. It is suggested that the protection afforded by this hyperimmune serum is due to high levels of specific antibody demonstrable in the serum of calves post treatment and that protection is given in this instance by antibodies contained in the IgG class of immunoglobulins.