Equine laminitis caused by distal displacement of the distal phalanx: 12 cases (1976-1985)

Clinical data from 12 cases of equine laminitis characterized by distal displacement of the distal phalanx (P3) were reviewed. Clinical features of horses that survived the syndrome were compared with the nonsurvivors to obtain prognostic indicators. Animals affected included 8 Quarter Horses, 2 Welsh ponies, 1 Thoroughbred, and 1 Arabian. Eight of the animals were females (67%), 2 were stallions, and 2 were geldings. The mean age of affected animals was 8.6 years (2 to 14 years), and the mean body weight was 442 kg. The survivors weighed less than the nonsurvivors (384 kg vs 473 kg, respectively), suggesting that body weight may be of prognostic value for horses affected with distal displacement of P3. Ten of the 12 animals (83%) were admitted because of a disorder other than laminitis, but subsequently developed laminitis during the treatment period. All affected animals had clinical evidence of endotoxemia and/or sepsis before the onset of laminitis. Cavitation or depression of the dorsal coronary band was detected in all animals and was the most reliable clinical indicator of distal displacement of P3. Five horses had fluid (blood or serum) ooze from their coronary bands and 2 of these sloughed one or more of their hooves. Necropsy findings of the 8 horses that were euthanatized included severe hemorrhagic, congested laminae and complete detachment of P3 from the hoof wall. Histologic examination of affected laminae revealed vascular thrombosis and multifocal areas of hemorrhage and necrosis. Radiography failed to reveal distal displacement of P3 in 8 animals, but the remaining 4 animals had an accentuation of the dorsal proximal hoof wall and cavitation of the coronary band visible on lateral radiographs.     

Uroperitoneum attributable to ruptured urachus in a yearling bull.

Ruptured urachus was found to result in uroperitoneum in a yearling Beefmaster bull. The uroperitoneum was initially believed to be attributable to ruptured bladder secondary to urolithiasis; however, catheter decompression of the bladder through an ischiatic urethrotomy did not resolve the uroperitoneum. The persistent urachus was diagnosed and removed through caudal right flank laparotomy with the bull standing. The urachus was attached to the umbilicus, communicated with the lumen of the bladder, and had a mucosal lining. Ruptured urachus is an unusual cause of uroperitoneum, but can cause clinical signs identical to those of ruptured bladder. Persistent urachus is a congenital abnormality in many species, but may be hereditary in Beefmaster cattle. In addition, the bull in this report developed hyperkalemia, which is considered an unusual finding in cattle with uroperitoneum.     

Abdominal adhesions after small intestinal surgery in the horse

One hundred thirteen of 172 horses (66%) undergoing exploratory celiotomy for a small intestinal lesion survived 4 or more days after surgery. Intra-abdominal adhesions causing clinical problems requiring additional surgery or euthanasia were documented in 25 horses (22.1%). Problems developed in significantly more males than females. The most common initial small bowel lesion was ileal impaction (12 horses); 21 horses underwent small intestinal resection or bypass. However, there was no significant difference in the incidence of intra-abdominal adhesions between horses that underwent intestinal resection or bypass and those that did not. Only 4 of the 25 horses (16%) with problems associated with postoperative adhesions survived. The mean interval between surgical procedures or between the initial procedure and euthanasia for all horses was 84 days (range, 7-512 days; median, 25 days). However, 70% of the subsequent celiotomies were performed within 60 days of the previous surgery. The mean interval between celiotomies was 221 days (range, 9-512 days) for the survivors and 61 days (range, 7-358 days) for the nonsurvivors. These results indicated that most of the problems related to postoperative intra-abdominal adhesions occurred within 2 months of the initial small intestinal surgery. Furthermore, the earlier development of postoperative adhesions was associated with a poorer prognosis for survival.     

Modified transfixation pinning of compound radius and ulna fracture in a heifer

A 405-kg heifer sustained a compound fracture of the distal portion of the radius and ulna after being hit by a car. The fracture was thoroughly debrided, lavaged, and reduced with the heifer under general anesthesia. The fracture was immobilized with a modified walking cast, using 2 fully threaded 6.4-mm (outside diameter) Steinmann pins placed through the proximal portion of the radius. The pins were incorporated into a full-limb fiberglass cast, and a 0.5-cm X 2.25-cm aluminum walking bar was positioned medially and laterally on the limb. The modified walking cast was removed after 7 weeks, and the fracture healed without complication. The transfixation pins and aluminum walking bar helped reduce the strong compressive and rotational forces at the fracture site. The modified walking cast can potentially be used for fixation of a variety of fractures in large animals.     

Effects of exploratory laparotomy on plasma and peritoneal coagulation/fibrinolysis in horses

Plasma and peritoneal fluid samples were collected before and after surgery from 6 horses undergoing a ventral midline exploratory laparotomy and from 6 anesthetized control horses. Coagulation/fibrinolytic components measured in the plasma and peritoneal fluid of these horses included the functional activity of antithrombin III, alpha-2 antiplasmin, plasminogen, and protein C, and the concentrations of fibrinogen and fibrin degradation products. Peritoneal fluid antithrombin III, fibrin degradation products, and plasminogen values were significantly increased after surgery (over time) in principal horses. Compared with control horses, postoperative peritoneal fluid from horses undergoing laparotomy had significantly increased antithrombin-III activity at 12 and 72 hours, alpha-2 antiplasmin activity at 24 hours, fibrin degradation product concentrations at 6, 12, 24, 72, 96, and 144 hours, plasminogen activity at 6, 12, 24, 48, 72 and 96 hours, and protein-C activity at 12, 24, 72, and 96 hours. There were no significant changes in the peritoneal fibrinogen concentration in principal horses. Plasma plasminogen activity was significantly decreased at 24 hours after surgery in principal horses, compared with controls. Changes were minimal in the remaining plasma coagulation/fibrinolytic components of horses undergoing laparotomy. Plasma and peritoneal fluid values of anesthetized control horses did not change.     

Fecundity of anthelmintic resistant adult Haemonchus contortus after exposure to ivermectin or benzimidazoles in vivo

A strain of Haemonchus contortus resistant to the benzimidazoles, ivermectin and salicylanilides was used to study the effect of exposure to ivermectin or oxfendazole on the number of eggs produced by adult female parasites. After anthelmintic administration there was a reduction in the faecal egg count of the infected lambs. Ivermectin caused a reduction in the number of eggs within adult parasites for up to 72 hours but this returned to higher than pre-treatment levels at 168 hours after treatment. After oxfendazole treatment there was an increase in the number of eggs stored in the adult parasites at 24 hours and then a significant reduction in the number of eggs for over 168 hours. This suggested that both ivermectin and oxfendazole have a deleterious effect on the reproductive potential of female H contortus although the parasites are resistant to these drugs. These results confirm the importance of allowing up to 10 days to elapse between the time of administration of an anthelmintic and the collecting of faecal samples when using the faecal egg count reduction test to identify anthelmintic resistance, especially when using benzimidazoles. The more prolonged effect on fecundity produced by oxfendazole may reflect the antimitotic action of the benzimidazole anthelmintics.     

Effect of aspirin on ex vivo generation of thromboxane in healthy horses

Different dosages of aspirin were administered (by nasogastric tube) to 3 groups of 5 healthy adult horses to determine the minimal effective dosage needed to decrease serum thromboxane B2 (TxB2) concentrations and to determine the duration of this decrease. When compared with their base-line serum TxB2 concentrations, horses in group 1 (given 5 mg/kg) had a 71% decrease in TxB2 concentrations at 24 hours after aspirin was given and a 86% decrease at 48 hours; serum TxB2 concentrations were back to base-line values by 120 hours. Horses in group 2 (given 10 mg/kg) had a 60% decrease in TxB2 concentrations at 24 hours after aspirin was given, an 84% decrease at 48 hours, a 48% decrease at 96 hours, and an 18% decrease at 6 days. Horses in group 3 (given 20 mg/kg) had a 68% decrease in TxB2 concentrations at 24 hours, a 93% decrease at 72 hours, an 87% decrease at 96 hours, and a 70% decrease at 6 days after aspirin treatment was given. All groups had a statistically significant decrease in TxB2 concentrations (P less than 0.05) by 12 hours after aspirin was given, which persisted 96 hours for group 1 and throughout the study for groups 2 and 3. The maximal TxB2 decrease was similar among the 3 groups (90% decrease from base line), and there were no significant differences among the TxB2 concentrations between 24 and 72 hours after treatment was given.(ABSTRACT TRUNCATED AT 250 WORDS)