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

The Effects of Domestication on the Brain and Behavior of the Chicken in the Light of Evolution

The avian class is characterized by particularly strong variability in their domesticated species. With more than 250 breeds and highly efficient commercial lines, domestic chickens represent the outcome of a really long period of artificial selection. One characteristic of domestication is the alterations in brain size and brain composition. The influence of domestication on brain morphology has been reviewed in the past, but mostly with a focus on mammals. Studies on avian species have seldom been taken into account. In this review, we would like to give an overview about the changes and variations in (brain) morphology and behavior in the domestic chicken, taking into consideration the constraints of evolutionary theory and the sense or nonsense of excessive artificial selection.

Gastrointestinal Diseases of Rabbits

Gastrointestinal stasis syndrome is a very common presentation of an ill rabbit to the veterinarian. The causes involved in this syndrome are often multifactorial, and an inappropriate diet puts the rabbit at a greater risk of developing this syndrome. Complications of this disorder can lead to gastrointestinal obstruction, a life-threatening condition that necessitates aggressive medical and in some case surgical therapy. Rabbits may also be presented with signs of diarrhea. However, abnormal cecotrophs must be differentiated from true intestinal diarrhea. The common causes, diagnosis and management of diarrhea including dysbiosis and enteritis are discussed. Other important causes of gastrointestinal disease are infectious disease and liver lobe torsion. Rabbit hemorrhagic disease virus has a new variant that has been identified in mainland Europe, the United Kingdom, and Australia. Subclinical infection of intestinal coccidiosis is a common cause of weight loss in adult rabbits. Liver lobe torsion is a challenging condition to diagnose in rabbits; this chapter discusses the presenting signs, diagnostic techniques, and therapeutic options.

The KIT gene is associated with the english spotting coat color locus and congenital megacolon in Checkered Giant rabbits (Oryctolagus cuniculus)

The English spotting coat color locus in rabbits, also known as Dominant white spotting locus, is determined by an incompletely dominant allele (En). Rabbits homozygous for the recessive wild-type allele (en/en) are self-colored, heterozygous En/en rabbits are normally spotted, and homozygous En/En animals are almost completely white. Compared to vital en/en and En/en rabbits, En/En animals are subvital because of a dilated (“mega”) cecum and ascending colon. In this study, we investigated the role of the KIT gene as a candidate for the English spotting locus in Checkered Giant rabbits and characterized the abnormalities affecting enteric neurons and c-kit positive interstitial cells of Cajal (ICC) in the megacolon of En/En rabbits. Twenty-one litters were obtained by crossing three Checkered Giant bucks (En/en) with nine Checkered Giant (En/en) and two en/en does, producing a total of 138 F1 and backcrossed rabbits. Resequencing all coding exons and portions of non-coding regions of the KIT gene in 28 rabbits of different breeds identified 98 polymorphisms. A single nucleotide polymorphism genotyped in all F1 families showed complete cosegregation with the English spotting coat color phenotype (θ = 0.00 LOD  = 75.56). KIT gene expression in cecum and colon specimens of En/En (pathological) rabbits was 5–10% of that of en/en (control) rabbits. En/En rabbits showed reduced and altered c-kit immunolabelled ICC compared to en/en controls. Morphometric data on whole mounts of the ascending colon showed a significant decrease of HuC/D (P<0.05) and substance P (P<0.01) immunoreactive neurons in En/En vs. en/en. Electron microscopy analysis showed neuronal and ICC abnormalities in En/En tissues. The En/En rabbit model shows neuro-ICC changes reminiscent of the human non-aganglionic megacolon. This rabbit model may provide a better understanding of the molecular abnormalities underlying conditions associated with non-aganglionic megacolon.