Ceri E. Sherlock

Deep erosions of the palmar aspect of the navicular bone diagnosed by standing magnetic resonance imaging.

REASONS FOR PERFORMING STUDY Erosion of the palmar (flexor) aspect of the navicular bone is difficult to diagnose with conventional imaging techniques. OBJECTIVES To review the clinical, magnetic resonance (MR) and pathological features of deep erosions of the palmar aspect of the navicular bone. METHODS Cases of deep erosions of the palmar aspect of the navicular bone, diagnosed by standing low field MR imaging, were selected. Clinical details, results of diagnostic procedures, MR features and pathological findings were reviewed. RESULTS Deep erosions of the palmar aspect of the navicular bone were diagnosed in 16 mature horses, 6 of which were bilaterally lame. Sudden onset of lameness was recorded in 63%. Radiography prior to MR imaging showed equivocal changes in 7 horses. The MR features consisted of focal areas of intermediate or high signal intensity on T1-, T2*- and T2-weighted images and STIR images affecting the dorsal aspect of the deep digital flexor tendon, the fibrocartilage of the palmar aspect, subchondral compact bone and medulla of the navicular bone. On follow-up, 7/16 horses (44%) had been subjected to euthanasia and only one was being worked at its previous level. Erosions of the palmar aspect of the navicular bone were confirmed post mortem in 2 horses. Histologically, the lesions were characterised by localised degeneration of fibrocartilage with underlying focal osteonecrosis and fibroplasia. The adjacent deep digital flexor tendon showed fibril formation and fibrocartilaginous metaplasia. CONCLUSIONS Deep erosions of the palmar aspect of the navicular bone are more easily diagnosed by standing low field MR imaging than by conventional radiography. The lesions involve degeneration of the palmar fibrocartilage with underlying osteonecrosis and fibroplasia affecting the subchondral compact bone and medulla, and carry a poor prognosis for return to performance. POTENTIAL RELEVANCE Diagnosis of shallow erosive lesions of the palmar fibrocartilage may allow therapeutic intervention earlier in the disease process, thereby preventing progression to deep erosive lesions.

Surgical drainage and post operative lavage of large abdominal abscesses in six mature horses.

Six mature horses with large abdominal abscesses (defined as an abscess >15-20 cm in at least one dimension) were treated by surgical drainage and post operative lavage. The abscess was associated with previous intestinal surgery in one horse, and with Streptococcus equi spp. equi infection in the other 5. A Foley catheter was used to drain and lavage the abscess in all cases. The abscess was accessed by a ventral midline laparotomy in 5 cases and by standing flank laparoscopy in one. Two horses were subjected to euthanasia within 7 days due to persistent or recurrent colic. The other 4 horses survived. Lavage of the abscess was continued for a median time of 19 days. Antibacterial therapy was continued until the plasma fibrinogen concentration was normal (median 47 days). Follow-up information was obtained at a median of 1.8 years. All 4 horses were alive at the time of follow-up; 2 horses had suffered one or more bouts of colic that had responded to medical treatment.

Ex vivo comparison of three hand sewn end-to-end anastomoses in normal equine jejunum.

REASONS FOR PERFORMING STUDY Although single layer techniques are preferred in man and small animals for small intestinal end-to-end anastomoses, double layer techniques are more popular in equine surgery. This study was undertaken to evaluate the ex vivo characteristics of 2 single layer anastomoses in comparison to the traditionally performed double layer anastomosis in equine jejunum. OBJECTIVES To compare ex vivo: 1) construction time; 2) bursting pressure; and 3) lumen size reduction of 3 suture patterns (double layer simple continuous/Cushing pattern [2C]; single layer Lembert pattern [1L]; and single layer Cushing pattern [1C]) for end-to-end equine jejunojejunostomies. METHODS End-to-end jejunojejunostomies were constructed using 2C (n = 7), 1L (n = 7) and 1C (n = 7) in harvested equine jejunum and construction times were recorded. Anastomosed and control segments were distended with gas until failure. Intraluminal pressure at failure and mode of failure were recorded. Lumen size reduction was calculated as a percentage decrease from control jejunum. Results were compared using an ANOVA and P<0.05 was considered significant. RESULTS The 1C anastomoses were faster to construct than the 1L anastomoses, which were faster to construct than the 2C anastomoses. There were no differences in bursting pressures between the different anastomoses and control jejunum. All anastomoses decreased lumen size from control values but there were no differences in lumen reduction between types of anastomoses. CONCLUSIONS Single layer anastomoses are faster to construct than double layer anastomoses, with the 1C being fastest. Single layer anastomoses are as strong and result in comparable lumen size reduction as traditional 2C anastomoses. POTENTIAL RELEVANCE As the 1C anastomosis results in less exposed potentially adhesiogenic suture material than the 1L while providing adequate strength and similar luminal size reduction, the 1C may be better for equine small intestine anastomosis and further in vivo studies are warranted.

COMPUTED TOMOGRAPHIC APPEARANCE OF MELANOMAS IN THE EQUINE HEAD: 13 CASES.

Melanomas are one of the most common neoplasms in the horse and are frequently found in the head region. There is a genetic predisposition in horses with a gray hair coat. Computed tomography (CT) is frequently used in referral practice to evaluate the equine head but there are few reports describing the CT appearance of melanomas in this location. The aim of this retrospective, case series study was to describe characteristics in a group of horses with confirmed disease. Case records from two referral hospitals were reviewed, and 13 horses were identified that had undergone CT of the head, with a diagnosis of melanoma based on cytology, histopathology, or visual assessment of black (melanotic) tissue. A median of 11 melanomas was identified per horse (range 3-60), with a total of 216 masses. Melanomas were found most frequently in the parotid salivary gland, guttural pouches, surrounding the larynx and pharynx and adjacent to the hyoid apparatus. In noncontrast CT images, all melanomas were hyperattenuating (median; 113.5 Hounsfield units (HU), IQR; 26 HU) compared to masseter musculature (median; 69 HU, IQR; 5.5 HU). Fifty-six (25.9%) masses were partially mineralized and 41 (19.4%) included hypoattenuating areas. Histopathological assessment of these melanomas suggested that the hyperattenuation identified was most likely a result of abundant intracytoplasmic melanin pigment. Melanomas of the equine head appeared to have consistent CT features that aided detection of mass lesions and their distribution, although histopathological analysis or visual confirmation should still be obtained for definitive diagnosis.

In vitro comparison of a single-layer (continuous Lembert) versus two-layer (simple continuous/Cushing) hand-sewn end-to-end jejunoileal anastomosis in normal equine small intestine.

Objectives To compare in vitro physical and mechanical characteristics of 1-layer and 2-layer end-to-end jejunoileostomy. Study Design In vitro experimental study. Animals Adult horses (n = 6). Methods Harvested equine jejunum and ileum was used to create 1- and 2-layer end-to-end jejunoileostomy specimens. Construction time, bursting pressure, and relative lumen diameter (anastomosis diameter expressed as a percentage of the lumen diameter of adjacent jejunum and ileum) were compared. Construction time and relative lumen diameters were compared using a paired t-test. Bursting pressure for anastomoses and control jejunal segments were compared using a repeated-measure ANOVA. Statistical significance was set at P < .05. Results Mean (±SEM) construct completion times were shorter for 1 layer (21 ± 0.91 minutes) than 2 layers (26.71±1.16 minutes; P = .005). Relative lumen diameters (percentage of jejunal diameter) were larger for 1 layer (77.67 ± 4.46%) than for 2 layers (69.37 ± 2.8%; P = .035). There were no significant differences in bursting pressures between the 2 groups and the control jejunum (P =.155) or relative lumen diameters (percentage of ileal diameter; P =.118). Conclusions One-layer jejunoileostomy can be created in a shorter time and maintain a larger anastomosis luminal diameter without compromising maximum bursting pressure when compared to 2-layer jejunoileostomy.OBJECTIVES To compare in vitro physical and mechanical characteristics of 1-layer and 2-layer end-to-end jejunoileostomy. STUDY DESIGN In vitro experimental study. ANIMALS Adult horses (n = 6). METHODS Harvested equine jejunum and ileum was used to create 1- and 2-layer end-to-end jejunoileostomy specimens. Construction time, bursting pressure, and relative lumen diameter (anastomosis diameter expressed as a percentage of the lumen diameter of adjacent jejunum and ileum) were compared. Construction time and relative lumen diameters were compared using a paired t-test. Bursting pressure for anastomoses and control jejunal segments were compared using a repeated-measure ANOVA. Statistical significance was set at P < .05. RESULTS Mean (± SEM) construct completion times were shorter for 1 layer (21 ± 0.91 minutes) than 2 layers (26.71 ± 1.16 minutes; P = .005). Relative lumen diameters (percentage of jejunal diameter) were larger for 1 layer (77.67 ± 4.46%) than for 2 layers (69.37 ± 2.8%; P = .035). There were no significant differences in bursting pressures between the 2 groups and the control jejunum (P =.155) or relative lumen diameters (percentage of ileal diameter; P =.118). CONCLUSIONS One-layer jejunoileostomy can be created in a shorter time and maintain a larger anastomosis luminal diameter without compromising maximum bursting pressure when compared to 2-layer jejunoileostomy.

A Retrospective Study Comparing the Outcome of Horses Undergoing Small Intestinal Resection and Anastomosis With A Single Layer (Lembert) or Double Layer (Simple Continuous and Cushing) Technique

OBJECTIVES To (1) compare postoperative complications and survival in horses after small intestinal resection and anastomosis using 2 anastomosis techniques (single layer Lembert; double layer simple continuous oversewn with Cushing), and (2) to compare outcome by anastomosis type (jejunoileostomy; jejunojejunostomy). STUDY DESIGN Retrospective case series. ANIMALS Horses (n = 53). METHODS Medical records (July 2006-July 2010) of all horses that had small intestinal resection and anastomosis. Horses were divided into groups based on technique and type of anastomosis. Comparisons of pre- and intraoperative findings (disease severity), postoperative complications, and survival rates were made between groups. RESULTS There were no differences in disease severity, postoperative complications, or survival between single layer (n = 23) or double layer (n = 31) anastomoses. There were no differences in disease severity or survival between jejunoileostomy (n = 16) or jejunojejunostomy (n = 38). There was a higher incidence of postoperative colic in hospital after jejunoileostomy (13/16) compared with jejunojejunostomy (18/38) (P = .0127). CONCLUSIONS Postoperative complications and survival are comparable between horses undergoing single layer and double layer small intestinal end-to-end anastomoses. With the exception of increased postoperative colic in the hospital, postoperative complications and survival after jejunoileostomy and jejunojejunostomy are also comparable.Objectives To (1) compare postoperative complications and survival in horses after small intestinal resection and anastomosis using 2 anastomosis techniques (single layer Lembert; double layer simple continuous oversewn with Cushing), and (2) to compare outcome by anastomosis type (jejunoileostomy; jejunojejunostomy). Study Design Retrospective case series. Animals Horses (n = 53). Methods Medical records (July 2006–July 2010) of all horses that had small intestinal resection and anastomosis. Horses were divided into groups based on technique and type of anastomosis. Comparisons of pre- and intraoperative findings (disease severity), postoperative complications, and survival rates were made between groups. Results There were no differences in disease severity, postoperative complications, or survival between single layer (n = 23) or double layer (n = 31) anastomoses. There were no differences in disease severity or survival between jejunoileostomy (n = 16) or jejunojejunostomy (n = 38). There was a higher incidence of postoperative colic in hospital after jejunoileostomy (13/16) compared with jejunojejunostomy (18/38) (P = .0127). Conclusions Postoperative complications and survival are comparable between horses undergoing single layer and double layer small intestinal end-to-end anastomoses. With the exception of increased postoperative colic in the hospital, postoperative complications and survival after jejunoileostomy and jejunojejunostomy are also comparable.

Clinical signs, treatment, and prognosis for horses with impaction of the cranial aspect of the base of the cecum: 7 cases (2000-2010).

OBJECTIVE To determine the clinical signs, treatment, and prognosis for horses with impaction of the cranial aspect of the base of the cecum (cecal cupula). DESIGN Retrospective observational case series. ANIMALS 7 horses with colic attributed to cecal cupula impaction. PROCEDURES Medical records were reviewed and horses that underwent exploratory celiotomy from 2000 through 2010 were identified. Horses with cecal cupula impaction and without other abdominal problems to which colic could be attributed were selected for inclusion in the study. Information regarding history, clinical findings, diagnostic testing, surgical findings and treatments, and treatments and complications after surgery was recorded. Rate of survival of horses to discharge from the hospital was determined. Long-term follow-up information was obtained with telephone questionnaires. RESULTS Cecal cupula impaction without other cecal abnormalities was identified in 7 horses during exploratory celiotomy. Although clinical signs varied, horses typically had mild signs of colic and nondiagnostic rectal examination findings but were in systemically stable conditions at the time of the initial evaluation. Typhlotomies were performed and impactions were resolved by means of lavage and evacuation. All horses survived to discharge from the hospital and lived ≥ 2 years after surgery. CONCLUSIONS AND CLINICAL RELEVANCE Results of this study suggested cecal cupula impaction was a novel type of cecal impaction that was uncommon. Impactions did not involve the cecal body or apex and hypertrophy of the cecal wall was not grossly detected. Impactions were successfully treated with typhlotomy, lavage, and evacuation. Horses had a good prognosis after surgical treatment.

Idiopathic Fibrosis of the Tunica Muscularis of the Large Intestine in Five Horses with Colic

Histological evidence of fibrosis affecting the outer layer of the large intestinal tunica muscularis was identified in five of 32 horses affected by colic. In three cases, foci of pale eosinophilia and vacuolation of myocytes were observed. These findings are suggestive of a degenerative and fibrotic abnormality in the outer layer of the tunica muscularis of the large intestinal smooth muscle of some horses with colic.

Effect of N-butylscopolammonium bromide on equine ileal smooth muscle activity in an ex vivo model

REASONS FOR PERFORMING STUDY N-butylscopolammonium bromide (NBB) is an anticholinergic agent used to treat spasmodic colic in horses. Intestinal smooth muscle spasm also occurs in horses with intraluminal intestinal obstructions, such as ileal impactions. The antispasmodic effects of NBB may be useful in managing ileal impactions, but the effects of NBB on equine ileal smooth muscle are unknown. OBJECTIVES To investigate the effects of NBB on spontaneous and induced contraction of the equine ileum in an ex vivo model. STUDY DESIGN Ex vivo biomechanical study assessing contractile properties in isolate equine ileal smooth muscle with and without exposure to NBB. METHODS Ileal tissue was collected from 6 healthy horses after euthanasia, and isolated circular and longitudinal smooth muscle strips were connected to isometric force transducers in organ baths. After equilibration, the effect of NBB (1 nmol/l to 100 μmol/l) on spontaneous and carbachol-induced contraction was determined and compared with responses in control tissue. RESULTS At ≥30 μmol/l, NBB inhibited spontaneous contractions in all muscle strips that exhibited spontaneous activity. N-butylscopolammonium bromide pre-treatment inhibited carbachol-induced contraction in circular (NBB-treated half maximal effective concentration [EC₅₀] 0.530 × 10(-8) mol/l vs. control EC₅₀ 41.57 × 10(-8) mol/l) and longitudinal muscle strips (NBB-treated EC50 0.243 × 10(-8) mol/l vs. control EC₅₀ 90.84 × 10(-8) mol/l). Abolition of carbachol-induced contraction with NBB was observed at lower concentrations in circular than longitudinal muscle strips. Pretreatment with NBB significantly inhibited carbachol-induced contractions; NBB-treated tissue required greater carbachol concentrations to produce sustained contractions than control muscle strips. Histamine-evoked contraction was not affected by NBB. CONCLUSIONS N-butylscopolammonium bromide inhibits spontaneous and cholinergically mediated contraction in equine ileal smooth muscle strips ex vivo. Thus, NBB might reduce intestinal spasm in equine ileal impactions and could be useful for medical management of these cases, although further study is needed to confirm these effects in vivo.