Open Approach to the Transversus Abdominis Plane in Horses: A Cadaver Feasibility Study.

The study's objective was to evaluate the feasibility and dispersion of an open approach to the transversus abdominis plane (TAP) block in eight adult equine cadavers. A ventral midline incision was made, starting 2 cm cranial to the umbilicus and extending 25 cm cranially. In total, 0.5 mL/kg of new methylene blue (NMB) was injected per horse, divided into six injections. Using an 18 g, 8 cm Tuohy needle, three injections were made per side. The needle was guided blindly into the TAP using palpation. A 60 mL syringe was attached directly to the needle, depositing ~0.08 mL/kg at each site. The time to complete the injections was recorded for each cadaver. Following injection, the ventral body wall was dissected to determine if the dye was present within the TAP space as well as to measure the extent of the dispersion of the dye, the cranial to caudal extent, and the width of the dye's spread. Complete deposition of NMB into the TAP (six of six sites) was achieved in 5/8 horses. The median time needed to perform all the injections was 263 s. Increased adiposity (retroperitoneal fat) was associated with unsuccessful injections. This approach to the TAP was easily and quickly performed, though less successful in horses with increased retroperitoneal fat and increased BCS.

In vitro evaluation of the effect of tris-EDTA and 0.0005% chlorhexidine solution on the strength of two absorbable sutures.

OBJECTIVE: To determine the effect of 0.0005% chlorhexidine and tris-EDTA solution on the strength of three commonly used suture types for closure of equine ventral midline celiotomy. STUDY DESIGN: Controlled laboratory study. SAMPLE POPULATION: Knotted loops (n = 10/group, 150 knot constructs total). METHODS: Strands of 2 polyglactin 910, 3 polyglactin 910, and 2 polydioxanone were tied to form knotted loops. All knotted loops were mounted on a tabletop force measurement machine system and loaded at 100 mm/min until the breaking force (N) was determined. The breaking force (N) of knotted loops using dry suture was recorded at study start, then of knotted loops soaked in either 0.0005% chlorhexidine and tris-EDTA for 20 min followed by incubation in equine serum (treatment) or serum alone (control) for 14 and 21 days. Analysis of variance (ANOVA) compared the breaking force between the treatment and control groups at each time point. RESULTS: There was no significant difference in the breaking force of 2 USP polyglactin 910 (p = .35, confidence interval [CI] = -0.21-0.59), 3 USP polyglactin 910 (p = .61, CI = -0.41-0.24), or 2 USP polydioxanone (p = .76, CI = -0.63-0.46) soaked in 0.0005% chlorhexidine and tris-EDTA solution followed by equine serum when compared to each respective suture soaked in equine serum only. CONCLUSION/CLINICAL SIGNIFICANCE: Since 0.0005% chlorhexidine and tris-EDTA solution did not exhibit a significant effect on the breaking force of the absorbable sutures studied, the solution may be used for incisional lavage in the clinical setting.

Colic Surgery: Recent Updates.

The following article provides an overview of the last 5 years of research and innovation within the field of equine colic surgery, focusing on new techniques, new or recently described lesions, prevention of lesion recurrence or postoperative complications, and updates in prognoses. Early surgical intervention is an important factor in horse survival.

Multi-Institutional Retrospective Case-Control Study Evaluating Clinical Outcomes of Foals with Small Intestinal Strangulating Obstruction: 2000-2020.

Lower survival has been reported in foals than adults with small intestinal strangulating obstruction (SISO), but age-dependent outcomes have not been examined directly. Hospital records were collected from five US academic referral hospitals. It was hypothesized that foals would exhibit lower survival than case-matched adults. Foal cases 6-months-of-age or younger, and adult cases between 2- and 20-years-of-age were collected. Data revealed 24 of 25 (96.0%) foals and 66 of 75 (88.0%) adults that were recovered from surgery for SISO survived to hospital discharge. Sixteen of the total 41 (39.0%) foals studied were euthanized intraoperatively, whereas 30 of 105 (28.6%) adults were euthanized intraoperatively. Common lesions in foals that were recovered from surgery were volvulus (n = 13) and intussusception (n = 5), whereas common lesions in adults were volvulus (n = 25) and strangulating lipoma (n = 23). This study was limited by incomplete medical records, relatively small sample size, and lack of long-term follow-up. Unexpectedly, short-term survival tended to be higher in foals than adults and may have been partly driven by case selection prior to referral or surgery or decision-making intraoperatively. More optimism toward surgical treatment of foals with SISO may be warranted.

Risk factors for laminitis and nonsurvival in acute colitis: Retrospective study of 85 hospitalized horses (2011-2019).

BACKGROUND: Acute colitis is a serious cause of morbidity and death in horses. Recent studies have compared clinical features of coronavirus and salmonellosis, but no study has compared clinical features of enteric salmonellosis, coronavirus, and neorickettsiosis. HYPOTHESIS/OBJECTIVES: To identify risk factors for laminitis and nonsurvival to discharge in horses with enteric salmonellosis, coronavirus, or neorickettsiosis. ANIMALS: Eighty-five horses hospitalized for acute colitis from 2011 to 2019. METHODS: Retrospective case series. Medical record review (2011-2019) of adult (≥2 years) horses with colitis. Primary outcomes were laminitis and survival to discharge. Multivariable logistic regression was performed to assess association between variables and the development of laminitis. Stepwise Cox regression was performed to assess association between variables and survival. RESULTS: Seventeen of 85 (20%) horses developed laminitis during hospitalization. Neorickettsiosis cases (11/26, 42%) were more likely to develop laminitis than coronavirus (0/16, 0%) cases (odds ratio [OR] 24.48; 95% confidence interval [CI]: 1.33-451.74, P = .03). There was no significant difference in laminitis between salmonellosis and neorickettsiosis cases (OR 0.27; 95% CI: 0.07-1.07, P = .06). Admission heart rate (OR 1.08; 95% CI: 1.02-1.15, P = .01), total solids (OR 0.17; 95% CI: 0.06-0.54, P = .003), band neutrophils (OR 1248.47; 95% CI: 6.62-235 540, P = .008), and bicarbonate concentration (OR 0.68; 95% CI: 0.5-0.92, P = .01) were predictive of development of laminitis during hospitalization. Sixty-three of 85 (74%) horses survived to discharge: 16/16 (100%) coronavirus cases, 17/26 (65%) neorickettsiosis cases, 14/20 (70%) salmonellosis cases, and 16/23 (70%) unknown cases. Packed cell volume (hazard ratio [HR] 1.17; 95% CI: 1.09-1.26, P < .001), L-lactate concentration (HR 1.33; 95% CI: 1.14-1.55, P < .001), and development of laminitis (HR 7.07; 95% CI: 1.67-29.95, P = .008) were retained in the final multivariable model for prediction of nonsurvival to discharge. CONCLUSION AND CLINICAL IMPORTANCE: Nonsurvival and laminitis rates were high, likely related to the presence of neorickettsiosis in the region.

Serum amyloid A concentration in postoperative colic horses and its association with postoperative complications.

OBJECTIVE: To determine serum amyloid A (SAA) concentrations in the postoperative (PO) colic horse and its association with PO complications and infection. STUDY DESIGN: Prospective case series. ANIMALS: Fifty-one horses after colic surgery. METHODS: Blood samples from horses undergoing exploratory celiotomy were analyzed for quantitative SAA and fibrinogen concentrations and for neutrophil count at days 0, 1, 2, and 4-6 and at hospital discharge. RESULTS: Complications developed in 35 (69%) horses and included PO colic (n = 13, 25%), PO reflux (n = 11, 22%), intravenous catheter (IVC) complications (n = 11, 22%), low-grade fever (n = 11, 22%); surgical site infection (SSI; n = 9, 18%), high-grade fever (n = 7, 14%), and diarrhea (n = 4, 8%). There was an association between day 2 SAA and PO colic (P = .004), diarrhea (P = .042), IVC complications (P = .008), and PO reflux (P = .008) as well as day 4-6 SAA and PO colic (P = .004) and diarrhea (P = .018). Discharge SAA concentration was associated with SSI (P = .001). Fibrinogen concentrations at days 4-6 and at discharge were associated with PO colic (P = .003), diarrhea (P = .004), IVC complications (P = .002), and PO reflux (P = .023). No differences were seen in SAA, fibrinogen, or neutrophils between horses with PO infection vs those with non-infection-associated complications. CONCLUSION: Serum amyloid A was markedly increased in the PO period in all horses but did not differ between PO infection and noninfection complications. The amount of inflammation associated with PO colic and colic surgery was high and may have affected the predictive value of SAA for early PO infection. CLINICAL SIGNIFICANCE: Although increases occurred earlier, measurement of SAA with a point-of-care analyzer may not be a more sensitive indicator of infection in the early PO colic horse than fibrinogen concentration. Serum amyloid A may help detect SSI in the late PO period.

Physeal Fractures in Foals.

Physeal fractures are common musculoskeletal injuries in foals and should be included as a differential diagnosis for the lame or nonweightbearing foal. Careful evaluation of the patient, including precise radiographic assessment, is paramount in determining the options for treatment. Prognosis mostly depends on the patient's age, weight, and fracture location and configuration.

Outcome of Surgical and Medical Management of Cecal Impaction in 150 Horses (1991-2011).

OBJECTIVE: To evaluate short- and long-term outcome after medical and surgical management of horses with cecal impaction and to determine reasons for death or euthanasia. STUDY DESIGN: Retrospective case series. ANIMALS: Horses (n = 150). METHODS: Data collected from medical records (1991-2011) of horses with a diagnosis of cecal impaction, included signalment, history of recent disease/surgical procedure, admission data, management (medical, typhlotomy alone, jejunocolostomy), complications, and outcome. Short-term outcome (alive or dead at discharge) and long-term outcome (alive or dead at ≥1 year) were determined by telephone interview. Data were analyzed using a χ(2) or Fisher's exact test. Level of significance was P < .05. RESULTS: Of 150 horses hospitalized with a diagnosis of cecal impaction, 102 (68%) had a history of recent disease or a surgical procedure. Thirty-eight horses (25%) had cecal perforation at admission and 3 horses (2%) were euthanatized without treatment. Of 109 horses treated, 59 (54%) were managed medically and 50 (46%) surgically (typhlotomy [26]; jejunocolostomy [24]). The proportion of horses alive at hospital discharge was significantly lower for horses managed medically (61%) compared with surgically (82%; P = .02) but there was no difference between horses managed with typhlotomy alone (77%) or with jejunocolostomy (88%; P = .47). There were 57% of horses managed medically alive at 1 year. There was a similar proportion of horses alive at 1 year after typhlotomy alone (73%) and jejunocolostomy (70%; P = .86). CONCLUSIONS: Compared to the recent reports, the proportion of horses alive at hospital discharge was lower for both medically and surgically managed horses with cecal impaction. There was decreased survival for horses treated medically than those treated surgically; however, no significant difference was seen in survival between horses managed with typhlotomy alone versus jejunocolostomy.

Epiglottic abnormalities in mature nonracehorses: 23 cases (1990-2009).

OBJECTIVE: To identify history, clinical signs, endoscopic findings, treatment, and outcome of mature (> 8 years old) nonracehorses with epiglottic abnormalities. DESIGN: Retrospective case series. ANIMALS: 23 horses with an epiglottic abnormality. PROCEDURES: Medical records of horses examined between 1990 and 2009 because of an epiglottic abnormality were reviewed to obtain information on signalment, history, clinical signs, clinical examination findings, upper airway endoscopic findings, diagnosis, surgical procedure, clinical management, postoperative care, and outcome. RESULTS: Mean ± SD age was 16 ± 6 years (range, 9 to 30 years). Sixteen of the 23 (70%) horses had a primary complaint of a chronic cough. Thirteen (57%) horses had epiglottic entrapment, 7 (30%) had a subepiglottic granuloma, and 3 (13%) had a subepiglottic cyst. All 23 horses were treated surgically, with 1 (4%) requiring further surgical treatment. Follow-up examinations and conversations with owners indicated resolution of the primary complaint in 17 of the 23 (74%) horses, with 4 (24%) requiring prolonged medical treatment because of postoperative subepiglottic inflammation. Of the 6 horses without complete resolution, 4 (67%) had signs of recurrent airway obstruction and 2 (33%) developed persistent dorsal displacement of the soft palate following laryngotomy and subepiglottic membrane resection. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that coughing is a common complaint in mature nonracehorses with epiglottic abnormalities. Therefore, upper airway endoscopy is recommended in the evaluation of older horses with a cough. Surgical treatment can be beneficial in most horses, with some requiring further postoperative medical treatment.