Abstract: The clinical records of 100 cases of headshaking in horses were reviewed. Possible causes of the abnormal behaviour were identified in 11 animals; these included ear mite infestation, otitis interna, cranial nerve dysfunction, cervical injury, ocular disease, guttural pouch mycosis, dental periapical osteitis and suspected vasomotor rhinitis. However, in only two of these could it be shown that correction of the abnormality led to elimination of the headshaking. The additional clinical signs exhibited by the other idiopathic cases of headshaking included evidence of nasal irritation, sneezing and snorting, nasal discharge, coughing and excessive lacrimation. Many of these horses also showed a marked seasonal pattern with respect to the onset of the disease and the recurrence of signs in subsequent years. The clinical presentation of idiopathic headshakers and the seasonal incidence of the signs closely resemble allergic rhinitis in man.

Abstract: Sex differences in dispersal distance are widespread in birds and mammals, but the predominantly dispersing sex differs consistently between the classes. There has been persistent debate over the relative importance of two factors -- intrasexual competition and inbreeding avoidance -- in producing sex-biased dispersal, and over the sources of the difference in dispersal patterns between the two classes. Recent studies cast new light on these questions.

Abstract: Interventions in aggressive disputes were investigated in a free-living troop of vervets (Cercopithecus aethiops sabaeus) in Barbados. Interventions on behalf of kin were more frequent than on behalf of non-kin. Both types of interventions were more likely when the intervening animal outranked the opponent; presumably because retaliation probability, and hence cost of intervening, is low against low ranking opponents. The number of interventions given on behalf of both kin and non-kin increased with the number of disputes in which they were involved. In contrast to kin interventions, the number of interventions given on behalf of non-kin was correlated with that received by non-kin, suggesting that reciprocation is a necessary component of non-kin interventions. Non-kin interventions were more likely when the recipient outranked the opponent, presumably because reciprocation probability is high. Pairs of non-kin form structured reciprocal relationships based on the proportion of interventions allocated to each other, and most non-kin interventions flowed through these relationships. Males intervened on behalf of non-kin more frequently than did females. The implications of the results for the evolution of kin and reciprocal altruism were discussed.

Abstract: Quantitative culture of R. equi in the feces of dams and foals, in the air of the stalls and in the soil of the paddocks was carried out on three horse-breeding farms during the foaling season. The isolation rates of R. equi from the feces of dams from the 3 farms suddenly increased to approximately 80% at the end of March, when the snow in the paddocks finished melting, and remained at that level during April and May. The mean number of R. equi and the isolation rate of R. equi from the feces of dams on the farms were investigated for 5 weeks before and 5 weeks after delivery. During the 10 weeks, there were no differences in the isolation rate or in the mean number of R. equi from the feces of dams. R. equi was first isolated from the feces of the foals born in February and the middle of March at 3-4 weeks of age, on the other hand, it was first isolated from the feces of foals born in the end of March and April at 1-2 weeks of age. The number of R. equi in the soil collected from the paddocks used by dams during the winter was approximately 10(2)-10(4) g-1 of soil during the experiment. R. equi was isolated from the air in the stalls at the end of March and the number of R. equi in the air increased particularly on dry and windy days.(ABSTRACT TRUNCATED AT 250 WORDS)