Non-surgical correction of nephrosplenic entrapment and colitis in a Quarter Horse

Abstract

A 16-year-old Quarter Horse was examined and observed to have acute signs of colic, pyrexia, and diarrhea. A nephrosplenic entrapment was detected via rectal palpation and confirmed with abdominal ultrasound. The nephrosplenic entrapment was resolved non-surgically with jogging and anti-inflammatory medication. Concurrent colitis, toxic laminitis, and inappetence were managed and the horse made a full recovery.

A 16-year-old Quarter Horse gelding was examined on-farm by a mixed animal veterinary practitioner in Cranbrook, British Columbia. The horse was reported to have developed signs of colic and decreased appetite within the previous 24 h. The client had administered 10 mL of phenylbutazone (Phenylbutazone Oral Paste; Summit Veterinary Pharmacy, Aurora, Ontario), 12 g, PO in the morning and 10 mL of flunixin meglumine (Flunixin Oral Paste; Summit Veterinary Pharmacy, Aurora, Ontario), 1500 mg, PO that evening. On initial evaluation, the horse had a temperature of 40.2°C, heart rate of 60 beat/min, respiratory rate of 16 breaths/min, congested mucous membranes, prolonged skin tent, sunken eyes, and weak motility in all gastrointestinal quadrants. The horse was sedated on-farm with xylazine (Nerfasin; Dechra Veterinary Products, Toronto, Ontario), 100 mg/mL administered intravenously (IV) at a dose of 16 mg/kg of body weight (BW) in addition to flunixin (Flunazine 50 mg/mL; Vétoquinol, Lavaltrie, Quebec), 1.3 mg/kg BW, IV for pain control and inflammation. A rectal examination revealed a congested spleen with meaty and very round edges that was easily palpable off the left lateral body wall. A nasogastric tube was passed into the stomach and no contents were retrieved.

Due to a suspected nephrosplenic entrapment, the horse was brought to the clinic for hospitalization and further assessment. An abdominal ultrasound showed the stomach size and duodenal diameter to be within normal limits and no free fluid was evident in the abdomen or thorax. Ultrasound examination of the left abdomen revealed small portions of the spleen and colon, but the left kidney was not visualized in the paralumbar fossa. Right abdominal ultrasound examination showed the right kidney and a possible “snow globe” shape to the right dorsal colon. An initial complete blood (cell) count indicated mild leukopenia including lymphopenia and neutropenia with band cells present, suggesting stress and acute infection. Total bilirubin was mildly elevated on an initial biochemistry panel, likely due to inappetence. Intestinal ischemia and necrosis were thought to be unlikely as blood lactate values were within normal range. Due to the onset of diarrhea ~24 h after arrival, a stool sample was collected and submitted to IDEXX Laboratories (Markham, Ontario) for a comprehensive Equine Diarrhea RealPCR^TM Panel to test for Potomac horse fever (Neorickettsia risticii), Salmonella spp., Escherichia coli, and Clostridioides difficile.

The horse was hospitalized for 3 d starting the morning of the initial farm visit and was discharged on the morning of the 4th day. An IV catheter was placed in the left jugular vein and retained for the full hospitalization period. An initial 15 L bolus of lactated Ringer’s solution (LRS) was administered IV on the first morning followed by 10 L of LRS the next day. An IV dose of 1 mg/kg flunixin was also administered q24h for the first 3 d with an additional dose of 0.5 mg/kg on the first evening of hospitalization. To treat the nephrosplenic entrapment, repeated 15 min bouts of continuous jogging in a round pen were initiated every 3 h followed by rectal palpation to determine if the colon had dislodged and returned to normal position. An IV injection of phenylephrine was not administered due to the risk of rupturing the congested spleen leading to hemorrhage. At 2300 h on the first night of hospitalization, resolution of the nephrosplenic entrapment was confirmed via an ultrasound of the left paralumbar fossa that indicated the spleen had returned to normal size and placement.

Given the onset of diarrhea, long-acting oxytetracycline (Oxyvet 200 mg/mL; Vétoquinol) was administered as an IV infusion in a 1-L bag of LRS over 30 min q24h for the first 3 d at an initial dose of 16 mg/kg followed by doses of 8 mg/kg on subsequent days. Temperature remained elevated at 39.5°C for the first 2 d of hospitalization but returned to normal by the third morning. Serum amyloid A (SAA) measured 1236 mg/L initially, indicating acute inflammation, likely associated with bacterial infection. Daily SAA values were taken, and measured 1456 mg/L on the second day, 1442 mg/L on the third day, and 2142 mg/L on the fourth morning before the horse was discharged. Total protein (TP) was also measured daily. Results were 6.8 g/100 mL on the first morning of hospitalization but dropped to 5.2 g/100 mL by the first evening, possibly due to the onset of diarrhea and protein-losing enteropathy. The TP remained constant at 6.0 to 6.2 g/100 mL for the remainder of the horse’s stay. Packed cell volumes (PCV) ranged from 32 to 35% for the duration of hospitalization; these were within the normal range.

On the second morning, warm dorsal hoof walls and bounding medial and lateral digital pulses were detected on the front 2 feet, indicating the onset of laminitis. No lameness was observed. Hoof icing every 4 h was initiated and continued for the next 2 d of hospitalization. By the third afternoon hoof warmness had resolved, and digital pulses had receded. Inappetence persisted throughout the horse’s stay, possibly due in part to rejection of hay available in-clinic. Diarrhea also persisted throughout the horse’s hospitalization, but the IDEXX equine diarrhea panel results were negative for all pathogens including Potomac horse fever.

The horse was discharged on the fourth morning with non-palpable digital pulses and normal vital signs without treatment with anti-inflammatory medication. Due to continued elevated SAA and soft stool, 5 days’ worth of penicillin (Depocillin 300 mg/mL; Merck and Co., Kenilworth, New Jersey, USA) was dispensed to be given intramuscularly (IM) at a dose of 23 mg/kg, q24h and flunixin paste (Flunixin Oral Paste 1500 mg; Summit Veterinary Pharmacy) was dispensed to be given orally at a dose of 0.7 mg/kg as needed for pain, but no more than twice daily. Equine Choice Paste 80 mL (Animal-Pro Products, Shakespeare, Ontario) was also recommended as a prebiotic/probiotic to help restore normal gut flora. Two days after discharge and 7 d after initial signs of colic, vital signs were normal with the horse showing a good appetite for grass but a reluctance to eat hay. Given the resolution of laminitis, an increased grass diet was deemed acceptable to increase feed intake. At 9 d after the onset of initial clinical signs, bowel movements were regular and solid, and appetite, vital signs, and digital pulses were normal.

Discussion

Nephrosplenic entrapments, also called left dorsal displacements, occur when a section of large colon is displaced dorsally and entrapped over the nephrosplenic ligament, resulting in colic (1). The cause is often unknown but is hypothesized to include gas accumulation, lack of gastrointestinal motility, or rolling (1). Nephrosplenic entrapments are typically resolved by 3 methods: non-surgical via jogging, non-surgical via general anesthetic followed by rolling, and surgical. Non-surgical treatment via jogging or rolling can be done with or without the use of phenylephrine to shrink the congested spleen, and surgical treatment employs either ventral midline celiotomy, standing flank laparotomy, or standing laparoscopy (1). A meta-analysis by Gillan et al (2) showed no difference in survival between surgical and non-surgical correction, no difference in medical resolution between jogging and rolling as non-surgical techniques, nor did the use of phenylephrine significantly improve chances of resolution of the entrapment with either non-surgical method. In this case, jogging was used as a first attempt to resolve the nephrosplenic entrapment as the least invasive method given that the horse was clinically stable. Absence of net stomach reflux on nasogastric intubation and normal blood lactate levels suggested a lack of initial complications such as duodenal occlusion by the colon or ischemic sections of intestine, further indicating conservative management initially to attempt to resolve the entrapment. Referral for possible surgical resolution was offered but the client declined. Phenylephrine was not used due to the potential for hemorrhage, which has been reported in rare cases (3). The nephrosplenic entrapment was resolved after approximately12 h of hospitalization, anti-inflammatory medication, and 3 bouts of jogging. Had the entrapment not resolved or the horse deteriorated further, the next step would have been to refer for surgical correction or to euthanize.

In this case the nephrosplenic entrapment was potentially brought on by the concurrent colitis. Although the equine fecal polymerase chain reaction (PCR) panel returned negative results for Neorickettsia risticii, clinical signs of fever, diarrhea, laminitis, mild colic, anorexia, tachycardia, and mild neutropenia along with the positive clinical response to oxytetracycline were consistent with colitis due to Potomac horse fever (PHF) (4). There is some evidence that PCR of fecal samples detects PHF 11 to 28 d after infection [summarized in Arroyo et al (5)], and clinical signs can appear 1 to 3 wk post-infection (4), suggesting the single fecal sample submitted from this case may not have coincided with the detectable period of PHF bacterium in feces by the available PCR methods. Repeated sampling at different times throughout the symptomatic period would increase the chances of detecting PHF via fecal PCR testing given an unknown infection date (4). In addition, a newly detected species capable of causing PHF in horses, Neorickettsia findlayensis, can be isolated by culture but is undetectable using current fecal PCR testing methods with further implications for false negative results when testing for clinical PHF infections (5,6). While awaiting results of the equine diarrhea PCR panel, the colitis and laminitis were managed symptomatically as PHF using oxytetracycline, cryotherapy, and supportive fluids. Positive response to PHF treatment, summer seasonality, and the client’s proximity to a marsh area and the Kootenay river further support PHF as the cause of the colitis.

In conclusion, although a fecal PCR test did not confirm the presence of PHF, clinical signs and response to treatment were consistent with infection which potentially led to a secondary nephrosplenic entrapment that was resolved non-surgically. Given a lack of significance between treatment methods for resolving nephrosplenic entrapments (2), medical management via jogging and anti-inflammatory medication without the use of phenylephrine should be considered for treating nephrosplenic entrapments when indicated, especially when surgery is not an option.