A multicentre, prospective, randomised, blinded clinical trial to compare some perioperative effects of buprenorphine or butorphanol premedication before equine elective general anaesthesia and surgery.

REASONS FOR PERFORMING STUDY: Buprenorphine, a µ-agonist opioid, has recently been licensed for equine use, but butorphanol, a κ-agonist opioid, is more commonly used in horses. The effect of the 2 opioids has not previously been compared in a large clinical study. OBJECTIVES: To compare post operative analgesia and physiological variables in horses undergoing elective surgery following premedication with either buprenorphine or butorphanol in a conventional clinical setting. STUDY DESIGN: Multicentre, prospective, randomised, blinded clinical investigation. METHODS: Eighty-nine healthy horses admitted for elective surgery to one of 6 UK equine veterinary clinics were premedicated with acepromazine, a nonsteroidal anti-inflammatory drug, and romifidine followed by intravenous (i.v.) buprenorphine or butorphanol. Anaesthesia was induced with diazepam/ketamine and maintained with isoflurane in oxygen. A range of surgical procedures were performed and supplementary anaesthetic agents given as required. Physiological variables were monitored during anaesthesia and pain, ataxia, sedation and vital function were assessed post operatively. Data were analysed using t-tests, ANOVA, Mann-Whitney U-test and Chi-squared test as appropriate and P<0.05 was regarded as significant, except for multiple comparisons, when P<0.01 was used. RESULTS: Surgery was carried out successfully in all cases and no mortality or serious morbidity occurred. Physiological variables remained within normal limits and all horses recovered successfully, most standing within 1 h of ceasing anaesthesia. There were no significant differences between groups in any variable except post operative pain when scores (simple descriptive scale) between 3 and 6 h were significantly lower after buprenorphine than after butorphanol. CONCLUSIONS: Horses experienced less post operative pain after buprenorphine than after butorphanol premedication. Compared with butorphanol, buprenorphine did not cause any different effects on vital function.

Fatal equine meningoencephalitis in the United Kingdom caused by the panagrolaimid nematode Halicephalobus gingivalis: case report and review of the literature.

A fatal case of eosinophilic and granulomatous meningoencephalitis caused by the free-living panagrolaimid nematode Halicephalobus gingivalis is reported in a 10-year-old Welsh gelding in the United Kingdom. Clinical examination first revealed behavioural abnormalities which rapidly progressed to severe ataxia, reduced mentation status and cranial nerve signs. Despite symptomatic treatment no amelioration of neurological signs was achieved and the horse was subjected to euthanasia. A complete post mortem examination revealed eosinophilic and granulomatous meningoencephalitis mainly affecting the cerebellum and brain stem with intralesional adult nematodes, larvae and eggs. There was also eosinophilic meningitis of the cervical spinal cord. The intralesional nematodes were morphologically consistent with the panagrolaimid nematode H. gingivalis. Although infection by this facultative neurotropic parasite is extremely rare, it needs to be considered in the differential diagnosis of central nervous signs in horses and, in particular, other equine helminthic infection of the central nervous system. This fatal case is unusual since lesions were locally very extensive and the nematodes did not colonise haematogenously to other organs as seen often in equine halicephalobosis. As the taxonomy of H. gingivalis has changed and some recent reports in the literature still refer to this species as Micronema deletrix or Halicephalobus deletrix, we here provide a short update of the species and some insights on the order Tylenchida, which contains free-living nematodes with parasitic tendencies.