Role of prokinetic drugs for treatment of postoperative ileus in the horse

All horses undergoing coeliotomy for an acute abdominal crisis are at risk of developing ileus and should receive therapy aimed at promoting gastrointestinal function by restoring fluid and electrolyte balance. Adequate analgesia and prevention against peritonitis, bacteraemia and endotoxaemia should be provided. Horses that at the time of surgery have a strangulating or non-strangulating small intestinal obstruction should be considered to be at greater risk of developing a persistent ileus that is refractory to treatment than those horses with lesions involving the large intestine. In horses considered to be at greater risk of developing a persistent ileus, the use of prokinetic agents should be considered. Agents that may be used to improve gastrointestinal motility include adrenergic receptor antagonists, cholinergic agonists, benzamides, dopamine antagonists, macrolide antimicrobials, opiate receptor agonists and antagonists, somatostatin analogues and local anaesthetics. There are limited studies into the use of these agents in the horse. Until further research provides more information on motility disorders following intestinal surgery and the efficacy of prokinetic agents in this species, only selective use of some of these drugs can be recommended.     

Acute febrile diarrhoea in horses: 86 cases (1986–1991)

SUMMARY: Eighty-six horses presented for examination at the Rural Veterinary Centre between January 1986 to December 1991 with acute diarrhoea. The average age of affected horses was 3.2 ± 0.2 years (mean ± SE), with 69% three years or younger. Sixty-one horses were male (36 stallions, 25 geldings) and 83 horses were Thoroughbreds (47) or Standardbreds (36). Sixty-six horses were undergoing routine training at the time of onset of diarrhoea. Eight horses were afflicted with a non-specific illness within one to five days before the onset of diarrhoea, whereas eight horses developed diarrhoea during or within 48 h of discontinuation of antimicrobial therapy. Three horses developed the diarrhoea within 24 h of road transportation. Clinically, the disorder was characterised by a fever, sudden onset of profuse diarrhoea, clinical evidence of dehydration (estimated to be 5 to 12% of body weight at the time of admission) and shock. Degenerative leucopaenia, hyponatraemia, hypochloraemia, hyperkalaemia, hyperglycaemia and azotaemia were characteristic laboratory findings. Laminitis was a sequel in about 30% of cases. The cause of diarrhoea remained undetermined in most cases. Salmonellas were isolated from faecal or tissue samples in only two cases. Similarly, there was no evidence of seroconversion to Erhlichia risticii in 17 cases. Sixty-two of the horses survived the acute phase of the disease in response to supportive care. In horses that did not survive, necropsies were performed and revealed sanguineous or turbid peritoneal fluid. The colonic and caecal walls were oedematous and thickened with serosal congestion and discolouration of these organs evident grossly. Histopathological examination of the caecum and colon revealed diffuse congestion, oedema, inflammatory reactions and submucosal vascular thrombosis with varying degrees of mucosal devitalisation. Most cases presented in this series represent a distinct syndrome of diarrhoea characterised by acute diarrhoea predominantly affecting young horses in training with concomitant signs of fever and toxaemia.     

Retropharyngeal lymph node infection in horses: 46 cases (1977–1992)

SUMMARY A retrospective study of 46 horses with retropharyngeal lymph node (RPLN) infection presented to the Rural Veterinary Centre between 1977 and 1992 was undertaken. Horses aged less than one year were most commonly represented (46%). Thirty-nine percent of cases had been exposed to horses with confirmed or suspected strangles (Streptococcus equi subsp equi infection) within the previous 8 weeks. Most frequent signs were unilateral or bilateral swelling of the throat region (65%), respiratory stertor/dyspnoea (35%), purulent nasal discharge (20%), inappetence and signs of depression (15%), and dysphagia (9%). All horses had a soft tissue density in the retropharyngeal region on radiographs. Rhinopharyngoscopy, ultrasonography, haematology as well as cytological and microbial analysis of material aspirated from the soft tissue swelling facilitated diagnosis in some horses. Fifteen horses (33%) were treated with procaine penicillin intramuscularly for 4 to 7 days followed by oral trimethoprim-sulphadimidine for 7 to 14 days. Non-steroidal anti-inflammatory drugs were administered to 6 horses. Four required tracheostomy for severe respiratory distress. The 15 horses treated medically responded to treatment and were discharged from hospital. Three horses (6%) with mild signs received no treatment and recovered uneventfully. Twenty-eight horses (61%) underwent general anaesthesia and surgical drainage of a RPLN abscess. Nineteen received procaine penicillin G for 4 to 7 days. Four of the nine horses that did not receive antibiotic treatment after surgery required further surgical drainage 10 days to 7 weeks after the initial surgery . Limited follow-up information was available for 37 horses. Thirty-two horses were considered to have made complete recovery, 3 horses had died through misadventure and 2 had been euthanased because of chronic ill-thrift .     

Marine and freshwater climatic factors affecting interannual variation in the timing of return migration to fresh water of sockeye salmon (Oncorhynchus nerka)

Interannual variation in the timing of the return migration to fresh water of adult sockeye salmon, Oncorhynchus nerka, from 46 populations throughout the species North American range was examined in a broad analysis of how timing patterns are affected by marine and freshwater conditions. Migration timing data (measured at various points along the migration, including just prior to freshwater entry, just after freshwater entry, and near the spawning grounds) were examined for correlations with sea‐surface temperatures (SST) prior to migration and to freshwater temperatures and flows during migration. Following a spring–summer period with warm SST, populations from southwestern Alaska tended to return early, Fraser River populations returned late, and populations from other regions showed no consistent patterns. Similarities between interannual timing of both nearby and distant populations indicated the presence of common or coincidental influences on timing. When riverine conditions related to timing, high flows and low temperatures were associated with late migrations, low flows and high temperatures were associated with early migrations. However, even counting stations at upriver locations showed correlations with SST. Notwithstanding some inconsistencies among the many populations examined and the indirect nature of the inferences, the results supported the hypotheses that (i) interannual variations in salmon distributions at sea reflect temperature conditions, and (ii) the date when salmon initiate homeward migration is a population‐specific trait, largely unaffected by the fish's location at sea.