Congenital intestinal stenosis and Hirschsprung's disease: two extremely rare pathologies in a newborn puppy.

BACKGROUND: Hirschsprung's disease (HSCR) is a common congenital malformation of the enteric nervous system (ENS). During fetal development, ganglion cells of the ENS are derived from neural crest cells that migrate to the bowel. These cells reside principally in two ganglionated plexus: 1) The myenteric plexus, extending from the esophagus to the anus, and 2) submucous plexus, extending from the duodenum to the anus. In large animal species, there is a third plexus called Henle's or Schabadasch's plexus. ENS ganglion cells play a key role in normal gastrointestinal motility, respond to sensory stimuli and regulate blood flow. Both plexus show a high degree of independence from the central nervous system. Alterations in the embryonic development of the ENS can induce multiple pathologies in animal models and humans. CASE PRESENTATION: The present case was a female the fifth born in a litter of 5 puppies. At about 2-3 weeks of age, she suffered from abdominal distension, pain, and constipation. At approximately 8-10 weeks of age, the puppy started to vomit abundantly, and the regurgitated food appeared undigested. Progressive abdominal distention was observed, with quite visible peristaltic movements and more frequent vomiting episodes. The abdominal radiographs, based on AP and side projections, revealed an enlargement of the abdominal diameter and an increased width in the epigastric region. At 12 weeks of age, exploratory surgery revealed a stenotic segment in the jejunum, followed by a small transition zone and then a significantly reduced diameter. Immunohistochemical examinations were performed using antibodies against calretinin, S-100 protein, CD56, neuron specific enolase (NSE) and synaptophysin, which are the biological markers for diagnosing HSCR. CONCLUSION: A reduced number of ganglion cells (1-3 cells per ganglion) were found. There was no specific staining pattern for many of these; while for others, the pattern was compatible with HSCR. Surgical intervention to remove the stenotic section prolonged the life of the puppy for 13 years. Extremely rare pathologies such as that discussed herein should be studied to understand the pathophysiology and be able to diagnose small species in veterinary medicine in a timely fashion. To our knowledge, this is the first report of congenital intestinal stenosis and Hirschprung's disease in a newborn puppy.

3-D technology used to accurately understand equine ileocolonic aganglionosis.

Ileocolonic aganglionosis (ICA) is the congenital and hereditary absence of neurons that constitute the enteric nervous system and has been described in various species including humans - Hirschsprung's disease - and horses - overo lethal white syndrome (OLWS). Hirschsprung's disease affects circa 1 in 5,000 live births. At best, this disease means an inability to absorb nutrients from food (humans). At worse, in horses, it always means death. Despite our general understanding of the functional mechanisms underlying ICA, there is a paucity of reliable quantitative information about the structure of myenteric and submucosal neurons in healthy horses and there are no studies on horses with ICA. In light of these uncertainties, we have used design-based stereology to describe the 3-D structure - total number and true size - of myenteric and submucosal neurons in the ileum of ICA horses. Our study has shown that ICA affects all submucosal neurons and 99% of myenteric neurons. The remaining myenteric neurons (0.56%) atrophy immensely, i.e. 63.8%. We believe this study forms the basis for further research, assessing which subpopulation of myenteric neurons are affected by ileocolonic aganglionosis, and we would like to propose a new nomenclature to distinguish between a complete absence of neurons - aganglionosis - and a weaker form of the disease which we suggest naming 'hypoganglionosis'. Our results are a step forward in understanding this disease structurally.

Congenital large intestinal hypoganglionosis in a domestic shorthair kitten.

UNLABELLED: CLINICAL PRESENTATION AND INVESTIGATIONS: An 11-week-old female domestic shorthair kitten presented with a history of constipation since weaning. Abdominal distension was noted on physical examination and abdominal radiographs revealed a large volume of faeces in the descending and transverse colon. Colonoscopy was unremarkable and euthanasia was performed at the owners' request. DIAGNOSIS: The histological diagnosis of large intestinal hypoganglionosis was made post mortem. SIGNIFICANCE: This appears to be the first reported case of congenital hypoganglionosis in a kitten with histopathological confirmation of the diagnosis. It may potentially be a more common cause of constipation in kittens and young cats than has previously been suspected.

Congenital aganglionosis in a 3-day-old Holstein calf.

Necropsy of a 3-day-old Holstein heifer revealed proximal megacolon and distal colorectal hypoplasia. Histologically, the hypoplastic distal colon and rectum lacked submucosal and myenteric ganglia. Clinical history, physical examination, and pathologic findings were consistent with intestinal aganglionosis, a congenital anomaly well documented in humans and foals but not previously reported in cattle.

Foal with Overo lethal white syndrome born to a registered quarter horse mare.

A 16-hour-old white foal, born to a registered quarter horse mare, was examined for signs of colic. The foal had Overo lethal white syndrome, which causes ileocolonic agangliosis. This was confirmed by DNA testing. Since there is no treatment for Overo lethal white syndrome, the foal was euthanized.

Megacolon in pigs due to segmental colon aganglionosis.

Four pigs, each of about 8 weeks of age were submitted for pathological examination because of severe cachexia, combined with an enormous distension of the abdomen. In the herd, where these pigs originated from, these clinical signs were observed frequently for some period of time and stricture of the rectum was suspected. All pigs showed a severe cachexia, and most prominent in all pigs was a megacolon with large and distended colon and caecum and stenosis about 30 to 60 cm cranial of the anus. Tissue specimens were taken from the rectum, from the colon cranial and caudal of the stenosis and from the jejunum and examined histologically. Ganglia in the intestinal wall were examined immunohistochemically by using antibodies recognising neurofilament protein (kD 200). In all pigs submucosal and myenteric ganglia were absent in the post stenotic colon and rectum and in transverse section of the stenosis, whereas in the prestenotic colon of all pigs and also in the jejunum ganglia were present. Segmental aganglionosis of the colon is also known in humans (Hirschsprung disease) and other animal species and is considered as a congenital disorder. We also suggest a familiar background of the disease in these pigs.

A dinucleotide mutation in the endothelin-B receptor gene is associated with lethal white foal syndrome (LWFS); a horse variant of Hirschsprung disease.

Lethal white foal syndrome (LWFS) is a congenital anomaly of horses characterized by a white coat colour and aganglionosis of the bowel, which is similar to Hirschsprung disease (HSCR). We decided to investigate possible mutations of the endothelin-B receptor gene ( EDNRB ) in LWFS as recent studies in mutant rodents and some patients have demonstrated EDNRB defects. First, we identified a full-length cDNA for horse EDNRB . This cDNA fragment contained a 1329 bp open reading frame which encoded 443 amino acid residues. The predicted amino acid sequence was 89, 91 and 85% identical to human, bovine and mouse as well as rat EDNRB respectively, but only 55% identical to the human, bovine and rat endothelin A receptor (EDNRA). Secondly, sequence analysis, together with allele-specific PCR and the amplification-created restriction site (ACRS) technique, revealed a dinucleotide TC-->AG mutation, which changed isoleucine to lysine in the predicted first transmembrane domain of the EDNRB protein. This was associated with LWFS when homozygous and with the overo phenotype when heterozygous.

A missense mutation in the endothelin-B receptor gene is associated with Lethal White Foal Syndrome: an equine version of Hirschsprung disease.

Lethal White Foal Syndrome is a disease associated with horse breeds that register white coat spotting patterns. Breedings between particular spotted horses, generally described as frame overo, produce some foals that, in contrast to their parents, are all white or nearly all white and die shortly after birth of severe intestinal blockage. These foals have aganglionosis characterized by a lack of submucosal and myenteric ganglia from the distal small intestine to the large intestine, similar to human Hirschsprung Disease. Some sporadic and familial cases of Hirschsprung Disease are due to mutations in the endothelin B receptor gene (EDNRB). In this study, we investigate the role of EDNRB in Lethal White Foal Syndrome. A cDNA for the wild-type horse endothelin-B receptor gene was cloned and sequenced. In three unrelated lethal white foals, the EDNRB gene contained a 2-bp nucleotide change leading to a missense mutation (I118K) in the first transmembrane domain of the receptor, a highly conserved region of this protein among different species. Seven additional unrelated lethal white foal samples were found to be homozygous for this mutation. No other homozygotes were identified in 138 samples analyzed, suggesting that homozygosity was restricted to lethal white foals. All (40/40) horses with the frame overo pattern (a distinct coat color pattern that is a subset of overo horses) that were tested were heterozygous for this allele, defining a heterozygous coat color phenotype for this mutation. Horses with tobiano markings included some carriers, indicating that tobiano is epistatic to frame overo. In addition, horses were identified that were carriers but had no recognized overo coat pattern phenotype, demonstrating the variable penetrance of the mutation. The test for this mutant allele can be utilized in all breeds where heterozygous animals may be unknowingly bred to each other including the Paint Horse, Pinto horse, Quarter Horse, Miniature Horse, and Thoroughbred.

Inhibitory neurotransmission in lethal spotted mutant mice: a model for Hirschsprung's disease.

BACKGROUND & AIMS: The pathogenesis of Hirschsprung's disease is not well understood. The suitability of the animal model for the unknown pathogenesis of inhibitory neurotransmission in Hirschsprung's disease was investigated. METHODS: Circular smooth muscle strips from the internal anal sphincter (IAS) and distal colon (2, 6, 8, 16, and 24 mm from the anal verge) from normal and Ls/Ls mice (mice homozygous for the lethal spotting mutation that develop fetal megacolon after aganglionosis of the terminal colon) were prepared to record changes in isometric tensions in response to different agents and nonadrenergic, noncholinergic nerve stimulation by electrical field stimulation. RESULTS: Bethanechol was used to produce contraction of the smooth muscle strips of distal colon to record a decrease in the tension. Conversely, the IAS smooth muscle strips developed spontaneous tone. In the normal homozygous mice, electrical field stimulation caused a biphasic response, an initial decrease followed by an after-contraction, whereas in Ls/Ls mice, the predominant response was contraction. All smooth muscle strips from normal and Ls/Ls mice produced relaxation in response to sodium nitroprusside and vasoactive intestinal polypeptide. CONCLUSIONS: Ls/Ls mice may serve as an appropriate animal model to investigate the pathogenesis of the inhibitory neurotransmission in Hirschsprung's disease in the distal colon and IAS.

Pathophysiological and functional aspects of the megacolon-syndrome of homozygous spotted rabbits.

The Megacolon-Syndrome is a hereditary disease of homozygous spotted rabbits (En En). Investigations have been performed on some special traits related to functional aspects of the gut in comparison to vital heterozygous spotted rabbits (En en). It was found that En En rabbits showed significantly reduced sodium absorption rates across the wall of the cecum. Consequently, the dry matter content of the ingesta was reduced at this location, whereas the content of the ashes was increased. These results indicate that a further important pathogenetic aspect of this hereditary disease is an undue liquification of ingesta in proximal parts of the large intestine. Severe clinical problems, however, resulted from obstipation. This is concluded to be a late complication due to and modified by different stressors of endogenic and exogenic origin. Thus, there are some indications that an early site of spot-gene related effects might be the small intestine. This segment of the bowel was shorter and had an increased dry matter proportion of its wall when compared with heterozygous spotted rabbits. But a decreased proportion of dry matter within the wall of the large intestine was found. The latter could be an effect of the hypothyreotic state of metabolism in En En rabbits.

[The problems of spotted breeds of rabbits. 4. Morpho- and histometric findings in the CNS and thyroid glands and the hormone content in blood at slaughter of hybrid rabbits, and estimation of the heterosis effect]. / Zur Problematik der Scheckenzucht bei Kaninchen. 4. Mitteilung: Morpho- und histometrische Befunde am ZNS und der Schilddrüse sowie SH-Gehalte im Schlachtblut von Hybridkaninchen, Beurteilung des Heterosiseffektes.

Morpho- und histometric investigations of brains, pituitary and thyroid glands as well as thyroid-related functional parameters in the blood of purebred and hybrid rabbits revealed a predisposition to hypothyreotic conditions in homozygous, megacolon-prone genotypes. In addition to this also a hypoganglionotic state in different gut wall localizations was confirmed; pituitary traits however did not indicate a primary contribution of this gland to the syndrome, though some alterations were found, which are interpreted as secondary sv. symptomatic. Gender influences varied hormonal characteristics and disease manifestations too: A dramatic fall in severely diseased does with respect to T3-concentration as well as a seemingly more inactive thyroid gland compared to bucks underline hormonal influences. As a consequence of these results it is concluded, that hybridisation within spotted rabbits does not amend the inclination to megacolon in animals homozygous for the K (En) gene, though it may influence its manifestation.

[The "lethal white foal" syndrome]. / Das "Lethal-white-foal"-Syndrom.

The lethal white foal syndrome (congenital intestinal aganglionosis) was diagnosed by history, clinical signs and pathological findings in a female foal, born in March 1992, that was an offspring of two overo-spotted paint horses. The syndrome is a congenital innervation defect of the gastrointestinal tract. A literature review of this condition, relatively unknown in Germany, is given.

Megacolon with myenteric hypoganglionosis in a foal.

A 6-month-old Clydesdale filly had chronic abdominal distention and intermittent febrile episodes. Abdominal surgery revealed impaction of the right dorsal colon, which was relieved by evacuation of contents through an enterotomy. Four days after surgery, abdominal distention recurred and progressed. The filly was euthanatized. Necropsy revealed the right dorsal colon to be markedly distended with digesta. Microscopically, there was a marked reduction in myenteric ganglion cells in the right dorsal colon and cecum and mild to moderate reduction of myenteric ganglion cells in the left ventral and transverse colon.

Association of megacolon with a new dominant spotting gene (Dom) in the mouse.

A new semidominant mutation in the mouse is described. In heterozygotes it produces white spotting and a deficiency of myenteric ganglion cells in the colon and, in homozygotes it is lethal prior to 13 days of gestation. The mutation, called dominant megacolon, symbol Dom, is located on chromosome (chr) 15, 20.6 +/- 1.6 units proximal to Ca. Hairy ears, Eh, a semidominant gene also on chr 15 is shown to have a suppressing effect on crossing over in this section of chr 15.