Idiopathic muscular hypertrophy of the equine small intestine: 11 cases (1980-1991)

Recurrent Colic: Diagnosis, Management, and Expectations

Most recurrent episodes of non-specific colic are self-limiting, and the results of clinical examinations are unremarkable. Differentiating these cases from serious diseases can be difficult, but repeated evaluations are warranted. Horses presenting with very frequent bouts of colic are more likely to have serious diseases and a higher mortality rate compared to horses presenting with less frequent bouts of transient colic. Horses with recurrent bouts of prolonged colic are more likely to have motility issues or partial intestinal obstruction. Non-gastrointestinal diseases can also cause recurrent bouts of pain ("false colic"). Adhesions are common causes of colic following abdominal surgery.

Tulathromycin and Diclazuril Lack Efficacy against Theileria haneyi, but Tulathromycin Is Not Associated with Adverse Clinical Effects in Six Treated Adult Horses

Equine theileriosis, caused by Theileria haneyi and Theileria equi, leads to anemia, exercise intolerance, and occasionally, death. Theileriosis-free countries prohibit the importation of infected horses, resulting in significant costs for the equine industry. Imidocarb dipropionate is the only treatment for T. equi in the United States, but lacks efficacy against T. haneyi. The goal of this study was to assess the in vivo efficacy of tulathromycin and diclazuril against T. haneyi. Fourteen T. haneyi-infected horses were utilized. Six were treated with eight weekly 2.5 mg/kg doses of tulathromycin. Three were treated daily for eight weeks with 2.5 mg/kg diclazuril. Three were pre-treated with 0.5 mg/kg diclazuril daily for one month to determine whether low-dose diclazuril prevents infection. Following infection, the dose was increased to 2.5 mg/kg for eight weeks. Two infected horses remained untreated as controls. The horses were assessed via nested PCR, physical exams, complete blood counts, serum chemistry panels, and cytology. Tulathromycin and diclazuril failed to clear T. haneyi and the treated and control groups exhibited similar parasitemia and packed cell volume declines. To obtain additional safety data on tulathromycin use in adult horses, necropsy and histopathology were performed on tulathromycin-treated horses. No significant lesions were detected.

Localisation of Cannabinoid and Cannabinoid-Related Receptors in the Horse Ileum

Colic is a common digestive disorder in horses and one of the most urgent problems in equine medicine. A growing body of literature has indicated that the activation of cannabinoid receptors could exert beneficial effects on gastrointestinal inflammation and visceral hypersensitivity. The localisation of cannabinoid and cannabinoid-related receptors in the intestine of the horse has not yet been investigated. The purpose of this study was to immunohistochemically localise the cellular distribution of canonical and putative cannabinoid receptors in the ileum of healthy horses. Distal ileum specimens were collected from six horses at the slaughterhouse. The tissues were fixed and processed to obtain cryosections which were used to investigate the immunoreactivity of canonical cannabinoid receptors 1 (CB1R) and 2 (CB2R), and three putative cannabinoid-related receptors: nuclear peroxisome proliferator-activated receptor-alpha (PPARα), transient receptor potential ankyrin 1 and serotonin 5-HT1a receptor (5-HT1aR). Cannabinoid and cannabinoid-related receptors showed a wide distribution in the ileum of the horse. The epithelial cells showed immunoreactivity for CB1R, CB2R and 5-HT1aR. Lamina propria inflammatory cells showed immunoreactivity for CB2R and 5-HT1aR. The enteric neurons showed immunoreactivity for CB1R, transient receptor potential ankyrin 1 and PPARα. The enteric glial cells showed immunoreactivity for CB1R and PPARα. The smooth muscle cells of the tunica muscularis and the blood vessels showed immunoreactivity for PPARα. The present study represents a histological basis which could support additional studies regarding the distribution of cannabinoid receptors during gastrointestinal inflammatory diseases as well as studies assessing the effects of non-psychotic cannabis-derived molecules in horses for the management of intestinal diseases.

Small intestinal pseudodiverticulosis in a pony mare

A 14-y-old pony mare was referred after 30-d duration of intermittent pyrexia, anorexia, weight loss, and change in manure consistency. Physical examination revealed a palpable but reducible ventral abdominal mass. Transabdominal ultrasonography revealed multiple distended, hypomotile, and thickened small intestinal loops in close approximation with numerous, well-defined, hyperechoic masses. There was a large amount of echogenic peritoneal fluid; abdominocentesis revealed a neutrophilic and macrophagic inflammatory exudate, and a mixed bacterial population was cultured. Given the poor prognosis, the mare was euthanized. The autopsy findings included a large abdominal abscess, serosanguineous peritoneal fluid with fibrin strands, and ~50 outpouches communicating with the lumen and extending from the anti-mesenteric aspect of the duodenum, jejunum, and ileum. These structures were classified as pseudodiverticula based on the histologic absence of the tunica muscularis layer of the intestinal wall. Pseudodiverticula should be included as a differential etiology in horses when clinical signs consistent with colic, diarrhea, or weight loss are recognized and, when on examination, one or more organized masses are palpated or visualized on transabdominal ultrasound, as well as visualization of small intestinal loops with thickened walls.

Ex vivo comparison of ultrasonographic intestinal wall layering with histology in horses: A feasibilty study

Ultrasonography is increasingly being used as a clinical and research method for evaluating the gastrointestinal tract in horses, however published studies comparing ultrasonographic and histologic characteristics of equine intestinal wall layers are currently lacking. Objectives of this prospective, observational, methods comparison, case series study were to compare the layering pattern and thickness of the intestinal wall layers determined using ex vivo and in vivo ultrasonography with those determined using histology. For the ex vivo study, twelve horses were euthanized for reasons unrelated to gastrointestinal disease, and samples of the duodenum, jejunum, ileum, cecum, right dorsal colon, and small colon were collected and imaged sonographically ex vivo in an isotonic bath within 1 hour of euthanasia. For the in vivo study, ultrasonography was performed in four clinical cases, and findings were compared with histopathology. A 5-layer pattern of alternating echogenicity was observed in 70 of 72 ex vivo samples. Agreement between histologic and sonographic measurements was deemed good for all segments except the ileum. Formalin fixation did not alter the sonographic appearance or wall measurements. Findings from the four clinical cases illustrated the feasibility of also obtaining ultrasonographic images with sufficient sonographic detail in vivo to recognize wall layering and obtain comparable results to pathologic lesions. Findings from the current study can serve as background for future studies comparing ultrasonographic characteristics of the intestinal wall in horses with different gastrointestinal diseases.

Cases of intestinal smooth muscle hypertrophy/hyperplasia in pigeon and chickens

Intestinal smooth muscle hypertrophy and hyperplasia has been described in human and several mammal species. In birds, only one case of intestinal smooth muscle hyperplasia has been reported. This paper describes the anatomopathological and histological findings of three cases of intestinal smooth muscle hypertrophy/hyperplasia in two different avian species belonging to the family Gallinidae and Columbidae. Grossly, it involved all tracts of the small intestine. Histologically, hyperplasia involved the mucosal villi, muscularis mucosa and inner and outer layers of the tunica muscularis. Hypertrophy was apparently detected only in the inner circular muscle layer. Lack of submucosal plexuses was also observed in all three animals. The results confirm the remarkable histological difference between mammals and avian species and show as these pathological changes can occur in different species of birds.

CAUSES OF DEATH AND DETECTION OF ANTIBODIES AGAINST JAPANESE ENCEPHALITIS VIRUS IN MISAKI FERAL HORSES (EQUUS CABALLUS) IN SOUTHERN JAPAN, 2015-17

We performed postmortem examinations on seven Misaki feral horses (Equus caballus) and evaluated Misaki feral horses, Japanese wild boars (Sus scrofa leucomystax), domestic pigs (Sus scrofa), and wild Japanese macaques (Macaca fuscata fuscata) from 2015 to 2017 in Cape Toi, Kushima, Miyazaki Prefecture, southern Japan, for antibodies against Japanese encephalitis virus (JEV). Strongylus vulgaris infection with severe arterial lesions and hemomelasma ilei was present in all necropsied horses. We frequently found intestinal ulcers, perihepatitis filamentosa, and poor body condition. We recorded degenerative arthropathy in metacarpophalangeal joints in two cases and a fracture of the rib with diaphragmatic rupture in one case. A total of 73% (177/242) of horses were seropositive for JEV as tested by hemagglutination inhibition (HI). The HI data also revealed that 74% (59/80) of the wild boars, 67% (60/90) of the pigs, and 29% (22/75) of the wild monkeys were seropositive for JEV. Our findings showed that Strongylus spp. are still a risk to horses in this region, and that environmental factors such as topographic location of the pasture and steep slope may have caused of degenerative arthropathy and bone fracture. Our results showed that JEV is endemic in Japan. The wild boars and pigs were presumed to act as strong amplifiers and sources of infection, with subsequent risk to humans.

Pseudodiverticula of the Small Intestine Associated With Idiopathic Smooth Muscle Hypertrophy in Domestic Rabbits (Oryctolagus cuniculus)

Acquired outpouches of the intestinal tract are referred to as pseudodiverticula or false pulsion diverticula. In contrast to true diverticula, in which the wall contains all layers of the intestinal tract, the wall of pseudodiverticula lacks the tunica muscularis. Smooth muscle hypertrophy of the small intestine is commonly considered a cause of pseudodiverticulosis in animals due to increased intraluminal pressure. This study reports pseudodiverticula associated with idiopathic smooth muscle hypertrophy of the small intestine in lagomorphs. Four domestic rabbits had single or multiple (up to 200) pseudodiverticula of various size in the small intestine. In all cases the tunica muscularis was diffusely thickened, significantly exceeding reference thickness of 14 rabbits (mean, 112.3 µm; range, 26.3–389.0 µm). Clinical signs were considered to be caused by severe necrosis and inflammation of the wall of large pseudodiverticula, leading to perforation with subsequent peritonitis and mesenteric and omental abscess formation in 2 cases.

Ileal hypertrophy and associated true diverticulum as a cause of colic in a horse

A 4-year-old Thoroughbred gelding underwent an explorative celiotomy for a suspected small intestinal obstruction. During surgery, an impacted diverticulum of the ileum was suspected, necessitating a jejunocaecostomy. The owner opted for euthanasia. On post-mortem examination and histopathology, a true diverticulum on the mesenteric side of the ileum, with ileal hypertrophy, was diagnosed.

Ultrasound of the equine acute abdomen

Abdominal ultrasound is an invaluable aid in the evaluation of the colic patient but can be heavily influenced by patient preparation, individual horse-to-horse variation, availability of ultrasound transducers, technique, experience level of the examiner, and complexity of the abdominal disorder. This article describes ultrasonographic anatomy of the normal equine abdomen and technique for examination of the equine colic patient. Common abnormalities of the stomach, small intestine, large intestine, and peritoneal cavity are described along with other abnormalities that may be discovered with abdominal ultrasonography of the colic patient, such as masses, urolithiasis, cholelithiasis, and thoracic or cardiac lesions.

Application of the lactose 13C-ureide breath test for measurement of equine orocaecal transit time

REASONS FOR PERFORMING STUDY

Application of the lactose (13) C-ureide breath test (LUBT) for measurement of equine orocaecal transit time (OCTT) has not been reported previously. The ability to assess OCTT noninvasively, and to investigate its relationship to gastric emptying rate and small intestinal transit, would be of both clinical and research value.

OBJECTIVES

1) Assessment of the LUBT in healthy horses, with comparison of induced versus noninduced test protocols. 2) Application of a new dual stable isotope breath test (lactose (13) C-ureide and (13) C-octanoic acid) for gastrointestinal transit measurement.

HYPOTHESIS

The LUBT will allow quantification of equine OCTT, and test efficacy will be enhanced by prior administration of lactose (12) C-ureide as shown in vitro. The dual tracer breath test will permit simultaneous measurement of gastric emptying, OCTT and small bowel transit times.

METHODS

Induced and noninduced LUBTs were performed in 3 healthy mature horses in randomised order using a standard test meal and protocol. Combined LUBT and (13) C-octanoic acid breath tests ((13) C-OABT) were performed in 4 individuals on 4 occasions at weekly intervals. Expiratory isotopic recovery was modelled to allow generation of gastric emptying data, small bowel transit times and caecal transit parameters.

RESULTS

The induction protocol for the LUBT increased the rate and magnitude of expiratory (13) CO(2) significantly. Mean ± s.d. values for OCTT, caecal lag phase (t(lag) ) and caecal t(1/2) using the induced LUBT were 3.24 ± 0.65 h, 5.62 ± 1.22 h and 6.31 ± 1.21 h, respectively. Dual stable isotope tests resulted in the production of 2 discrete peaks in expiratory (13) CO(2) in 15/16 tests from which gastric t(1/2), OCTT and small bowel transit (SBT) parameters could be calculated.

CONCLUSIONS

The induced LUBT provides a reliable noninvasive measure of equine OCTT and can be paired with the (13) C-OABT to provide further information about small intestinal motility.

Sympathetic innervation of the ileocecal junction in horses

The distribution and chemical phenotypes of sympathetic and dorsal root ganglion (DRG) neurons innervating the equine ileocecal junction (ICJ) were studied by combining retrograde tracing and immunohistochemistry. Immunoreactivity (IR) for tyrosine hydroxylase (TH), dopamine beta-hydroxylase (DBH), neuronal nitric oxide synthase (nNOS), calcitonin gene-related peptide (CGRP), substance P (SP), and neuropeptide Y (NPY) was investigated. Sympathetic neurons projecting to the ICJ were distributed within the celiac (CG), cranial mesenteric (CranMG), and caudal mesenteric (CaudMG) ganglia, as well as in the last ganglia of the thoracic sympathetic chain and in the splanchnic ganglia. In the CG and CranMG 91 +/- 8% and 93 +/- 12% of the neurons innervating the ICJ expressed TH- and DBH-IR, respectively. In the CaudMG 90 +/- 15% and 94 +/- 5% of ICJ innervating neurons were TH- and DBH-IR, respectively. Sympathetic (TH-IR) fibers innervated the myenteric and submucosal ganglia, ileal blood vessels, and the muscle layers. They were more concentrated at the ICJ level and were also seen encircling myenteric plexus (MP) and submucosal plexus (SMP) descending neurons that were retrogradely labeled from the ICJ. Among the few retrogradely labeled DRG neurons, nNOS-, CGRP-, and SP-IR nerve cells were observed. Dense networks of CGRP-, nNOS-, and SP-IR varicosities were seen around retrogradely labeled prevertebral ganglia neurons. The CGRP-IR fibers are probably the endings of neurons projecting from the intestine to the prevertebral ganglia. These findings indicate that this crucial region of the intestinal tract is strongly influenced by the sympathetic system and that sensory information of visceral origin influences the sympathetic control of the ICJ.

Idiopathic muscular hypertrophy of the oesophagus in the horse: a retrospective study of 31 cases

REASONS FOR PERFORMING STUDY

To present the first report of a case series concerning equine idiopathic muscular hypertrophy of the oesophagus (IMHO).

OBJECTIVES

To investigate the clinical and pathological features of the disorder.

METHODS

The medical records of 31 horses suffering from the disorder were reviewed retrospectively. In all these animals the diagnosis was confirmed at post mortem examination.

RESULTS

The median age of the affected horses was 12.5 +/- 5.6 years (range 1-26) without sex or breed predilection. Only 2 out of 31 horses showed clinical signs associated with oesophageal dysfunction, indicating that the muscular hypertrophy was rather a coincidental post mortem finding. Histology revealed thickening of the distal portion of the oesophagus mainly involving the circular layer of the tunica muscularis without fibrosis or inflammation. In 8 cases, the disorder was seen in concurrence with idiopathic hypertrophy of the tunica muscularis of various other parts of the gastrointestinal tract.

CONCLUSIONS

In the majority of patients, IMHO was a coincidental finding at post mortem examination usually confined to the smooth, circular muscle layer of the tunica muscularis externa.

POTENTIAL RELEVANCE

Further research is necessary to study the precise effect of IMHO on oesophageal function.

Ultrasonographic and pathologic features of intestinal smooth muscle hypertrophy in four cats

The ultrasonographic findings for four cats with intestinal smooth muscle hypertrophy are described. In two cats, intestinal smooth muscle hypertrophy was associated with chronic enteritis. In the remaining two cats, intestinal smooth muscle hypertrophy affected the intestinal tract proximal to stenosis due to alimentary lymphoma and an intestinal foreign body, respectively. Moderate increased thickness of the affected intestinal wall, measuring 7-8 mm, was evident on abdominal ultrasonographic examination of all subjects. In addition, the ultrasonographic five-layered feature of the intestinal wall was maintained, and only the muscular layer appeared thickened. Abdominal ultrasound allowed a presumptive diagnosis of intestinal smooth muscle hypertrophy that was confirmed histologically in all cats.

Hypertrophy of intestinal smooth muscle in cats

Pathological findings of four cats with severe and diffuse smooth muscle hypertrophy of the small intestine (MHSI) are reported and compared to those of five cats with segmental MHSI secondary to neoplastic obstruction and four controls. Histology demonstrated a constant association between idiopathic MHSI and submucosal fibrosis and chronic lymphoplasmacytic enteritis. Morphometry (gut diameter, thickness and area of muscular layers, number and density of smooth muscle nuclei) and MIB-1-immunolabelling showed that the thickness increase was mostly due to hypertrophy, but hyperplasia was also evident. Microbiology from ileal content samples was performed in two cats with primary MHSI, and Campylobacter spp. were isolated, which were also demonstrated by immunohistochemistry and ultrastructure. The association of chronic enteritis with idiopathic MHSI suggests that factors released in intestinal inflammation may also act as hypertrophy stimuli for smooth muscle cells.

Equine lymphocytic-plasmacytic enterocolitis: a retrospective study of 14 cases

Lymphocytic-plasmacytic enteritis (LPE) is a morphological diagnosis given to a type of infiltrative intestinal disease classified within the complex of idiopathic inflammatory bowel disease (IBD). The purpose of this retrospective study was to describe the details of breed, age and sex, clinical and clinicopathological findings and outcome of horses diagnosed with LPE. Data were reported from 14 horses that had a histopathological diagnosis of LPE; the median age was 12 years, and there was no breed or sex predilection. Common clinical signs were weight loss (100%), diarrhoea (50%) and lethargy (50%). Hypoproteinaemia and hypoalbuminaemia were present in 6/13 (46%) and 9/12 (75%) horses, respectively. Results of the oral glucose tolerance tests or D-xylose absorption tests were abnormal in 9/12 (75%) horses and rectal mucosal biopsies were abnormal in 3/7 (43%) horses. Corticosteroid treatment was used unsuccessfully in 4 horses. All horses were subjected to euthanasia and LPE was diagnosed at necropsy. Diffuse thickening of the small intestine was apparent grossly in 10/13 (77%) horses examined. LPE is an uncommon equine intestinal disease that is difficult to diagnose antemortem and has a poor prognosis.

Surgical reduction of ileal impactions in the horse: 28 cases

OBJECTIVE

To evaluate the seasonal influence, signalment, type of hay consumed, clinical examination findings, and outcome after surgery for horses with ileal impaction.

STUDY DESIGN

A retrospective study.

RESULTS

Between 1988 and 1993, 28 horses had surgical correction of ileal impaction. There was a significantly higher rate of ileal impaction during the Fall (September-November, P = .0041 ). Mean duration of clinical signs of abdominal pain before referral was 15 hours. Transrectal palpation was used to localize the impaction in 11 horses. The ileal impaction was reduced by extraluminal massage aided by admixing of intestinal fluid oral to the impaction or injection of fluids intraluminally and then movement of the ingesta into the cecum alone in 24 horses. A total of 26 horses recovered from surgery; 24 horses were discharged from the hospital and eventually returned to previous use. Two horses had fatal postoperative complications: jejunocecostomy dehiscence and development of extensive small intestine adhesions after manual reduction of the impaction. One horse initially treated by manual reduction required jejunocecostomy twice for management of recurrent ileal impaction. Follow-up information was obtained for 21 horses, of which 20 were alive 1 year or longer after surgery. A total of 27 of 28 horses were fed Coastal Bermudagrass hay as the primary type of hay consumed. A total of 9 horses continued to be fed Coastal Bermudagrass hay as the only roughage source, whereas 6 horses were fed Coastal Bermudagrass with at least 50% other hay, and in 6 horses, Coastal Bermudagrass hay was entirely eliminated from the diet.

CONCLUSION AND CLINICAL RELEVANCE

Ileal impactions can be successfully reduced by celiotomy and extraluminal massage and injection techniques to soften the ingesta for passage into the cecum without enterotomy or bypass techniques in most horses. Changes in weather and feeding practices in the Fall may account for an increased risk of ileal impaction in horses in the southeastern United States at that time of year.