Influence of Fluid Therapy on Gentamicin Pharmacokinetics in Colic Horses

The aminoglycoside antibiotic gentamicin is commonly used in equine medicine for the prevention and treatment of Gram-negative and staphylococcal bacteria in surgically treated colic patients. The pharmacokinetics of gentamicin in these patients might be altered by the disease status, and/or under the influence of fluid therapy. The purpose of this study was to investigate the effect of intravenous fluid treatment on gentamicin kinetics in colic patients. Colic patients subjected to laparotomy were given fluid infusions according to clinical status. Following gentamicin administration, blood samples were taken for gentamicin analysis at different time points, and the main pharmacokinetic parameters including Vc, Vss, t(1/2) and MRT were calculated. Horses undergoing fluid therapy showed a significantly different t(1/2), clearance and MRT as compared to non-infused patients. However, taking into account the clinical status of the patients receiving fluid support, the data suggest that endotoxaemia, rather than fluid therapy, influence gentamicin pharmacokinetics following laparotomy.     

Trends in the management of horses referred for evaluation of colic: 2004–2017

The financial crisis of 2008 had effects on veterinary practice, with falling turnovers associated with reluctance of owners to spend money on veterinary care. There were anecdotal reports that fewer horses were undergoing colic surgery. The aims of this study were to document the numbers of horses with colic being referred to, and undergoing surgery and/or euthanasia, at two equine hospitals (a university based equine hospital in the United States [NC State] and a private equine hospital in the UK [Bell Equine]) over a 14-year period (2004–2017). There was a trend of declining total yearly equine accessions at NC State starting in 2009, followed by an increase starting in 2012. At Bell Equine, total accessions showed an increasing trend from 2004 to 2015, followed by a slight decline in 2016 and 2017. The proportion of equine accessions that were colics varied from around 15% to 20% at both hospitals and did not show any notable variations over the time period studied. Both practices showed a trend of decreasing colic admissions undergoing and recovering from surgery starting from 2007 to 2008. The numbers and percentages of colic admissions that were subjected to euthanasia increased from 2004/2005 to 2014/2015 in both hospitals; there was a greater increase in numbers being subjected to euthanasia at surgery at NC State, compared to a greater increase in numbers being subjected to euthanasia without surgery at Bell Equine. At both hospitals, there was a trend of increasing mean invoice totals over the study period. The results show that there has been a trend of decreasing numbers of horses undergoing surgical treatment for colic since 2004/2005. This is likely to be, at least partly, due to the financial crisis of 2008, although other factors, including the high costs of surgery and the ageing equine population may also be important.     

Small intestinal segmental volvulus in horses after gastroscopy: Four cases (2011–2012)

Gastroscopy is the most common technique used in veterinary medicine to evaluate the stomach in horses and to date, no complications have been described associated with the procedure. This paper reports 4 cases developing a nonstrangulating segmental volvulus of the small intestine after gastroscopy at 3 referral institutions over a 2 year period. After performing diagnostic gastroscopy, all horses developed acute and severe clinical signs of colic unresponsive to medical management. Time range between gastroscopy and onset of colic signs varied from 10 min to 3 h. An exploratory laparotomy revealed a nonstrangulating segmental volvulus of the small intestine that was manually corrected without need for resection in all horses. In all cases, affected small intestine was severely gas distended. Three of those horses survived to discharge and were alive at follow‐up. One horse was subjected to euthanasia 2 days after surgery due to diffuse intestinal lymphoma.     

Surgical management of foreign body obstruction of the small and large colons in 29 equids (2004–2016)

The objectives of the study were to describe the clinical presentation, surgical findings, complications and outcome of a case series of small and large colon obstruction by foreign bodies (FBs) in horses. The study is a retrospective case series which included 29 equids (28 horses and one donkey). Medical records of cases diagnosed with FB obstruction of the large or small colon between the years 2004 and 2016 that underwent surgery were reviewed. Data regarding signalment, clinical signs, surgical findings and post-operative variables were recorded. Short- (survival to hospital discharge) and long- (1 year after surgery) term survival rates were obtained. Cases had a mean age of 4.2 years, with both females and Arabian horses being overrepresented. Abdominal distention was the most common observation on presentation and the FB could be palpated in 20% of the cases during rectal examination. The most common reason to go into surgery was severe pain with abdominal distention. Significantly more FBs were found in the small colon during surgery (P<0.0001) and most were removed by small colon enterotomy. Complications rate post-operatively was relatively high (41%) with fever and diarrhoea being most common. Twenty-three cases (79%) were released from the hospital and all cases that were available for long-term follow-up were alive and returned to previous activity. No correlation between the chosen method of surgical removal of the FB and survival or complications post-operatively was noted. These data reflect favourable prognosis for surgical removal of colonic FBs. Few techniques are available to improve the safety of removal and the preferred method depends on the FB location, appearance and mobility. As FB obstruction resembles ‘noncomplicated’ colonic impaction, it is essential to try and recognise FB cases since deterioration can be rapid and surgery is the only sufficient treatment.     

Caecal duplication in a 13‐year‐old Thoroughbred

A 13‐year‐old Thoroughbred gelding was presented for evaluation of recurrent colic of 4 weeks duration. These colic episodes were mild and responsive to medical therapy. Episodes of colic became more frequent and more painful. Exploratory laparotomy revealed a large intestine duplication with a cystic structure located at the caecocolic junction that was unable to be exteriorized and therefore not amenable to surgical correction. Thirty‐six hours following surgery, the horse became acutely painful, sweaty, and febrile suggesting gastrointestinal rupture. Post mortem examination showed a 0.6 × 1 m duplication and a 0.5 × 0.6 m cystic dilation that was probably associated with the caecum. There was a 10 × 30 cm area of rupture located within the duplication. Histological evaluation confirmed the presence of a true duplication.     

Surgical treatment of colic in the miniature horse: a retrospective study of 57 cases (1993-2006)

REASONS FOR PERFORMING STUDY: It has been suggested that the rate of post operative abdominal adhesions in miniature horses is higher than that for other breeds. However, few reports exist in the veterinary literature describing complications and long-term survival following surgical treatment of colic in these horses. OBJECTIVES: To determine the prevalence of surgical lesions in miniature horses with acute abdominal disease in terms of clinical signs, surgical management, post operative treatment and complications, as well as short- and long-term survival. METHODS: Medical records of 57 American Miniature Horses undergoing surgical treatment for acute abdominal pain at the Michigan State University Large Animal Veterinary Teaching Hospital 1993-2006 were evaluated for clinical information. Owners and trainers were contacted to gain information regarding long-term survival. RESULTS: The most common surgical lesion was a faecalith (38/57 cases) located primarily within the descending colon and most frequently diagnosed in horses age <6 months (19/38 cases). Short-term survival to hospital discharge for horses recovered from anaesthesia was 98% (55/56) with the most common post operative complications being diarrhoea and inappetance. Intra-abdominal adhesions were identified in 2/8 horses requiring a second celiotomy. Long-term follow-up was available for 45 horses and 87% (39/45) were alive at least 12 months after surgery. CONCLUSIONS: As previously reported, faecalith obstruction is a frequent surgical lesion in the miniature horse and is most common in miniature horses age <6 months. The incidence of adhesion formation may be lower than previously reported.     

A giant nonstrangulating mesenteric lipoma as a cause of recurrent colic in a horse

Colic is a major cause of veterinary attendance in general practice and although most colic episodes remain isolated, recurrence may occur and definitive diagnosis can be difficult to obtain. This report describes an unusual presentation of a lipoma in a middle‐aged horse presented for recurrent colic. A massive lipoma causing a nonstrangulating space occupying obstruction of the small intestine was found during an exploratory celiotomy and was considered to be the most likely cause of the recurrent episodes of abdominal discomfort.     

Two horses with thoracic lymphoma diagnosed using thoracoscopic biopsy

This report describes the use of thoracoscopy in 2 horses to obtain an antemortem diagnosis of thoracic lymphoma. The first horse in this report presented for assessment of weight loss and fever of unknown origin. The second presented with a history of upper respiratory tract noise and coughing during exercise. Although a strong clinical suspicion of neoplasia existed, a definitive antemortem diagnosis of thoracic lymphoma was not made in either case until biopsy samples obtained during standing thoracoscopy were examined.     

Laparoscopic‐assisted splenectomy in a horse with splenomegaly

This reports describes the surgical management of a horse evaluated for recurrent colic. These frequent colic episodes were attributed by exclusion to an abnormally enlarged spleen (idiopathic splenomegaly). Splenectomy was elected and performed with a laparoscopic assisted technique. The advantages observed by using this surgical approach were a clear view of the visceral aspect of the spleen and consequently an accurate dissection of the hilus of the spleen and associated vasculature. Ultimately the laparoscopic technique allowed the surgeons to reduce the size of the laparotomy incision required to remove the spleen and the overall invasiveness of the procedure. The horse recovered well from the procedure and ultimately returned to the previous level of competitiveness.     

Clinical pathology and ultrasonographic findings from a Warmblood gelding with primary,severe, acute pancreatitis

A 24-year-old Warmblood gelding presented with a 6-hour history of recurrent colic signs of increasing severity. Upon presentation, he was mildly painful, tachycardic and tachypnoeic and had decreased borborygmi. Nasogastric intubation resulted in no net reflux and rectal palpation revealed an ascending colon impaction. Percutaneous abdominal ultrasonography revealed dilated, thickened and hypomotile loops of small intestine. Complete blood count revealed leucopenia with neutropenia and an increased packed cell volume. Serum biochemistry revealed hyperproteinaemia, hyperglycaemia, hypocalcaemia, hyperbilirubinaemia, hypercholesterolaemia and elevated liver enzymes. Despite sedation and fluid resuscitation, the gelding became severely colicky. A repeat ultrasound was performed, revealing a moderate amount of free fluid and a mass effect between the liver and right dorsal colon. Abdominocentesis yielded a yellow, turbid fluid containing free-floating white debris with an increased total protein and lactate concentration. Cytology of the fluid revealed necrotic mesothelial cells. The gelding was humanely euthanised due to poor prognosis. Necropsy revealed acute, severe pancreatitis and duodenitis. The mass effect on ultrasonography was retrospectively identified as the pancreas exhibiting a similar architecture to that seen in cases of acute pancreatitis in small animals.     

Accuracy of increased large-intestine wall thickness during ultrasonography for diagnosing large-colon torsion in 42 horses

Large-colon torsion is a common cause of colic in horses and has a worse prognosis and higher cost than other causes of surgical colic of the large colon. During large-colon torsion, the colon wall becomes thick due to vascular occlusion. Therefore, we hypothesized that detecting increased colon wall thickness during ultrasonography would be an accurate preoperative test for large-colon torsion. The sample population consisted of 42 horses that were admitted for surgical treatment of colic localized to the large colon. The diagnosis was confirmed at surgery or necropsy examination. Twelve (29%) of these horses were diagnosed with large-colon torsion. Duplicate ultrasonographic measurements of colon wall thickness were made at six abdominal locations and an average measurement was calculated. For four of these six sites, a significant difference (P < 0.005) was detected between horses with and without large-colon torsion. All four tests were moderately sensitive and highly specific for diagnosing large-colon torsion using five decision criteria. Using a ventral abdominal window, a colon wall thickness > or = 9 mm accurately predicted large-colon torsion in eight of the 12 horses (sensitivity, 67%; confidence interval [CI], 36-98%) and correctly predicted that large-colon torsion was absent in 28/28 horses (specificity 100%; CI, 98-100%). Intraobserver repeatability was assessed by evaluating the difference between the first and second measurements obtained, which was < or = 2 mm. Therefore, detecting increased large-colon wall thickness during ultrasonography is a reproducible and accurate preoperative test for large-colon torsion in horses with surgical colic localized to the large colon.