Case 1
A 2-year-old Haflinger filly was admitted after one week from the onset of clinical signs including mild anorexia, depression, rapid weight loss and stop of stool production. The filly was kept on pasture with a group of similar breed horses. Two of them had suffered from slight colic signs few days before and had died in few hours.
At presentation, the filly was cachectic and had ‘tucked up appearance’ to the ventral abdomen. Depression of mental status was evident, and head and neck were carried down. Muscle weakness, muscular fasciculations, and base narrow stance were also observed. Clinical examination revealed bilateral palpebral ptosis, dry and congested ocular and oral mucous membranes, including the nasal mucosa (rhinitis sicca), noisy breathing, and slight dehydration. Hearth rate was elevated (60 bpm) and rectal temperature was normal (37.5 °C). Slow and prolonged mastication without drooling was present. Signs associated with cranial nerves deficits were not found. Colic pain was absent but abdominal sounds were reduced. Rectal examination and nasogastric intubation were unremarkable. Ultrasound examination revealed reduced motility of both small and large intestine. Abdominocentesis was performed and peritoneal fluid analysis was within the normal limits. Blood work was unremarkable.
A presumptive diagnosis of EGS was made and early therapeutic treatment consisting of fluid therapy and flunixin meglumine (0.5 mg/Kg IV twice a day) was administred. In addition, highly palatable diet was provided, and half an hour in-hand walking twice a day was performed.
On day 2, the work up to investigate weight lost syndrome included complete dental examination, fecal examination, gastroscopy, and oral glucose tolerance test (OGGT). Considering low glucose peak at 120 min, partial malabsorption was the only abnormality detected.
On day 3 and 4 clinical signs worsened, the filly became anorexic, depressed, and fecal production was inconsistent. Partial parental nutrition consisting in 5 % glucose, 8,5 % aminoacids and 1 ml/45 kg vitamins (thiamine 12.5 mg/ml; niacinamide 12.5 mg/ml; pyridoxine 5 mg/ml; d-panthenol 5 mg/ml; riboflavin 2 mg/ml; cyanocobalamin 5 mg/ml) was added to fluid therapy. Based on non-diagnostic histological results, exploratory laparotomy was proposed but refused by the owner due to financial constrains.
On day 7, further worsening of clinical conditions occurred, the filly was extremely weak and with no interest in feeding. Therefore, on day 8 the owners required euthanasia for ethical concerns and agreed to necropsy.
At the post mortem examination, signs of rhinitis without substantial exudate and diffuse catarrhal colityphlitis were the only relevant findings. Tissue samples from ileum, cranial cervical and cranial mesenteric ganglia were fixed in 10 % buffered formalin for routine histological examination.
At histology, cranial cervical and cranial mesenteric ganglia showed severe loss of Nissl substance in numerous ganglion cells in association with increased number of satellite cells. Based on clinical evidence a diagnosis of chronic EGS was done (Fig. 1).
Case 2
A 5-year-old Maremmana mare was referred with a history of loss of appetite, dullness and mild colic signs in the last two days. Actually, the first signs had been observed a week before worsening up to presentation. One of the horses kept on the same pasture had shown similar signs and had died abruptly.
At presentation, tachicardia (68 bpm) and decreased gut motility have been reported. Colic pain was absent but the horse was dull, anorexic and dehydrated. Rectal temperature was normal (37.8 °C), mucous membranes were dry and capillary refill time was delayed (3 s). Rectal examination revealed the presence of a live and active fetus of 3–5 months and a firm mass in the caudal part of the abdomen consistent with colonic impaction. Small amount of dark brown and mucoid feces were present in the rectum. At nasogatric intubation no reflux was found. Abdominal ultrasound findings included reduced motility of small and large intestine, non-distended fluid-filled stomach, and large non-sacculated ascending colon. Ectasic vessels were not present and anechoic peritoneal fluid was slightly increased and easily detectable next to the xiphoid apophysis of the sternum. Peritoneal fluid analysis was unremarkable.
Hematology was within normal limit. No significant clinical abnormality was detected on serum chemistry except for an increase in creatinine and urea values (Creatinine: 5.15 mg/dl, normal range 1.2–1.9 mg/dl; Urea: 197 mg/dl, normal range 10–24 mg/dl), total protein content (Serum Total protein: 9.2 g/dl, normal range 5.7–7.9 g/dl) and blood lactate concentration (Lactate: 3.3 mmol/l, normal range 1.1–1.7 mmol/L) consistent with prerenal azotemia due to dehydration.
A presumptive diagnosis of large colon impaction was made and medical therapy, consisting of fluid administration (40 ml/kg/day of ringer lactate) and mineral oil 2–4 L / 500-kg BW by nasogastric tube, was applied.
On day 2 and 3 the mare was still depressed, anorexic, tachicardic (60–70 bpm), with further reduction in intestinal motility. Muscles fasciculation and bilateral ptosis were reported.
A phenylephrine test was performed by topical application of 0.5 % phenylephrine ophthalmic solution to the left conjunctival sac (Visumdriatic®, Visufarma SpA Rome). The right eye was used as a control. Temporary reversal of ptosis was observed on the treated eye after 30 min, confirming neurogenic Mūller superior tarsal muscle paralysis as the mechanism underlying the ptosis [32] (Fig. 2).
At transrectal palpation, although colon impaction was still present, greenish cow-like malodorous feces were detected in the rectal ampulla. Ultrasound examination revealed a fluid distended stomach and non-distended hypomotile small intestine. Fetus was live and active. On day 2, nasogastric tube passed through and 13 L of net reflux material were obtained in 12 h. No reflux was produced on day 3. Blood work revealed leukocytosis (12.300 wbc/ µL, reference range 5.4–14.3 wbc/µL) and fibrinogen content was slightly above the reference values (6.1 g/l, reference range 1–4 g/l). Urea and creatinine were returned within normal limits but total calcium (8.3 mg/dl, normal range 11.2–13.6 mg/dl) and potassium (2.1 mmol/l, normal range 2.4–4.7 mmol/l) were below reference values. KCl 30 mmol/l of polyionic solution and Ca gluconate 40 % 0,2 ml/kg were added to the ongoing fluid therapy (40 ml/kg/day of ringer lactate) for maintenance requirement.
On day 4 the mare showed moderate intermittent colic pain despite colonic impaction was no more detectable at rectal palpation. The mare interest for food improved but extreme dysphagia along with with patchy sweating and muscles fasciculation were observed during mastication. Serum chemistry and electrolyte (aspartate aminotrans- ferase (AST), gamma glutamyltransferase (GGT), creatine phosphokinase (CPK), total protein (TP), albumin (Alb), urea, creatinine (Crea), glucose (Glu), alkaline phosphstase (ALP), lactate dehydrogenase (LDH), total bilirubin (TB), direct bilirubin (DB), triglycerides (Tryg), cholesterol (Chol), calcium, phosphorus, magnesium, sodium, potassium, and chlorine) were within normal limits.
At night, between day 4 and day 5, the mare begun to show severe abdominal pain and congested mucous membranes. Blood lactate rised up (6.0 mmol/l). Transrectal examination was unremarkable and no reflux was obtained at nasogastric intubation. Ultrasonographic findings consisted of diffuse non-dilated hypomotile small intestine. The response to treatment (xilazine 0.4 mg/kg; flunixin meglumine 1.1 mg/kg) was poor and surgical treatment was refused by the owner due to financial constrains. The mare was humanly submitted to euthanasia.
Post mortem examination revealed a moderate right dorsal colon and descending colon impaction. Small intestine, particularly jejunum, was distended. Stomach content include Gasterophilus spp. larvae. Liver size was slightly increased. Fetus and fetus membranes were normal compared to the gestational age.
Multiple tissue specimens from all major organs were collected and fixed in 10 % buffered formalin, for routine histological staining. Histological findings consistent with EGS were observed in cranial and caudal mesenteric ganglia as well as in myenteric plexi (Additional file 1). As for gut, the lesions were more severe throughout the small intestine. Abnomal accumulation of lipofuscine in ganglion cells was also observed (Additional file 2).
Case 3
A 5-year-old Haflinger mare was referred with a history of 12 h dullness, anorexia and abdominal pain unresponsive to medical therapy (flunixin meglumine, 1.1 mg/Kg, twice a day). At presentation, moderate signs of abdominal pain were present. The horse was dull, anorexic, dehydrated, tachycardic (68 bpm), and presented bilateral ptosis. Dry, sub-icteric mucous membranes and slightly elevated rectal temperature (38.1 °C) were also reported. Intestinal sounds were completely absent and the mare presented a base-narrow (elephant on a tub) stance.
Rectal examination revealed a hard ascending colonic impaction.
At abdominal ultrasound anechoic peritoneal fluid was slightly increased, small intestine and ascending colon were distended and hypomotile, stomach was full of ingesta and fluid but not distended. Nasogastric intubation was unsuccessful since the lower esophageal sphincter was completely closed preventing the passage of the tube.
Blood work revealed an increased packed cell volume (30 %) and total protein concentration (9 g/dl). Blood lactate was 2.8 mmol/l. Peritoneal fluid analysis was unremarkable.
Ptosis resulted to be positive to phenylephrine test.
Since the horse was kept on the same pasture of the horses for which equine grass sickness had been previously diagnosed, a laparotomy was performed in order to both obtain an ileal biopsy and solve the impaction.
The day after surgery, the horse was dull and showed slight signs of pain. Four liters of reflux were obtained by nasogastric intubation, and further 5 L were recovered five hours later.
On day 3 and 4 the horse was still dull and anorexic. Heart rate was increased (65 bpm) and abdominal sounds were absent with no stool production. On day 3 gastric reflux was 3 L, and on day 4 it was 4 L.
Histological results of ileal biopsy (Fig. 3) were consistent with diagnosis of EGS.
Due to the clinical condition and worsening of colic pain, the horse was euthanized and submitted to necropsy in accordance with owner’s request. At necropsy, a large amount of ingesta was present inside the stomach and colon. Small amount of feaces covered by mucus were found in the small colon.
Post-mortem histological examination performed on ENS and cranial mesenteric ganglia confirmed findings consistent with EGS.
Case 4
A 6-year-old Haflinger mare was referred along with a 45-day-old foal. The mare was dull and anorexic, showing mild colic pain, base-narrow stance, bilateral ptosis, increased heart rate (90 bpm). Intestinal sounds were absent. A few mucus covered black faeces were present in the rectum, and a hard constipation was detected in the pelvic flexure.
No significant change was detected at blood work (complete blood count and same serum chemistry parameters and electrolyte as in case 2) and peritoneal fluid analysis was unremarkable.
At abdominal ultrasound, distended small intestine was found. Phenylephrine eye test was positive.
Therapy for constipation (40 ml/kg/day of ringer lactate and mineral oil 2–4 L / 500-kg BW by nasogastric tube) was started but on day 2 the mare was still anorexic and the clinical condition did not improve. No significant changes were found at gastroscopy.
Based on the history and clinical presentation, EGS was suspected and a standing laparoscopy was planned to collect full thickness ileal biopsy, as previously described [33]. Despite a slight improvement of the appetite and of the abdominal pain condition, on day 6, two days after surgery, the mare became again anorexic and dull, the abdominal sounds were still absent and no stool production was observed. Since histological findings of ileal biopsy were consistent with EGS (Fig. 4), the mare was euthanized. Histology of ENS and mesenteric ganglia sampled at post-mortem examination confirmed the diagnosis of EGS (Additional file 3).