Cryptosporidium cuniculus in the rabbit (Oryctolagus cuniculus)

Cryptosporidium cuniculus was identified by light and electron microscopy in two apparently healthy rabbits. Organisms were firmly attached at the brush borders of intestinal epithelial cells. Cellular alterations were minimal, consisting of elongation and shortening of microvilli adjacent to the attachment sites of organisms. Various developmental stages of cryptosporidium were identified by electron microscopy.     

Molecular Characterization of Enterocytozoon bieneusi in Domestic Rabbits (Oryctolagus cuniculus) in Northeastern China

A study of 426 rabbits from 3 cities in Jilin province (Changchun City and Jilin City) and Liaoning province (Shenyang City) was conducted between May and June 2015. The overall prevalence of E. bieneusi in rabbits was 0.94% (4/426), with 0% (0/116), 1.72% (3/174), and 0.74% (1/136) in Jilin, Changchun, and Shenyang City, respectively. Only 3 farms (farm 1 and farm 3 in Changchun City, farm 8 in Shenyang City) were PCR-positive for E. bieneusi. Moreover, rabbits of more than 6 months (1.72%) had the highest E. bieneusi prevalence, followed by rabbits of 4-6 months (1.26%), 2-3 months (0.58%), and less than 1 month (0%). Analysis of ITS gene of E. bieneusi suggested that all 4 E. bieneusi isolates were genotype D, and were classified as group 1a. The present results first demonstrated the existence of zoonotic E. bieneusi in domestic rabbits in China. Effective control measures should be implemented to prevent E. bieneusi infection in domestic rabbits, other animals, and humans.     

Rabbits (Oryctolagus cuniculus) select small seeds when feeding on the fruits of Corema album

Herbivores are hypothesized to consume fruits and seeds while foraging on the vegetative parts of plants. A small seed size is an important condition for this foliage-as-fruit hypothesis to be proved, but has received little attention at the intra-specific level. We measured Corema album seeds ingested by rabbits and those collected from plants and found that rabbits are actively selecting for small seeds. The mechanisms of this selection remain unclear, although my results discard (1) the phenology of consumption, (2) effects of gut passage, and (3) intra-plant heterogeneity of seed sizes as possible mechanisms.     

Routes of Intraspecies Transmission of Mycobacterium avium subsp. paratuberculosis in Rabbits (Oryctolagus cuniculus): a Field Study

Rabbits have been increasingly linked to the persistence of paratuberculosis (Johne's disease) in domestic ruminants in the United Kingdom. The aims of this study were to determine the routes of intraspecies transmission of Mycobacterium avium subspecies paratuberculosis (MAP) in rabbits and to estimate the probability of transmission via each route, in order to gain understanding of the dynamics of MAP in this host. Rabbits were sampled from two sites where MAP had previously been isolated from the livestock and rabbit populations. No pathology was noted in any animals, but the overall prevalence of MAP in rabbits was high at both sites studied, 39.7% and 23.0%, respectively. MAP was isolated from the testes, uterus, placenta, fetuses, and milk. This is the first time that the bacterium has been isolated from any of these tissues in a nonruminant wildlife species. These results suggest that transmission may occur vertically, pseudovertically, and horizontally. Vertical, i.e., transplacental, and/or pseudo-vertical, i.e., through the ingestion of contaminated milk and/or feces, transmission occurred in 14% of offspring entering the population at 1 month of age. As infection via these routes is only possible from infected adult females, this equates to a probability of infection via this route of 0.326. Probability of infection via horizontal transmission (including interspecies transmission) occurred at up to 0.037 per month. The presence of these routes of transmission within natural rabbit populations will contribute to the maintenance of MAP infections within such populations and, therefore, the environment.     

Coccidia in rabbits (Oryctolagus cuniculus) in Saudi Arabia

Kasim A. A. and Al-Shawa Y. R. 1987. Coccidia in rabbits (Oryctolagus cuniculus) in Saudi Arabia. International Journal for Parasitology17: 941–944. Seven species of coccidia were identified and described for the first time in Saudi Arabia in 263 faecal samples of domestic rabbits (Oryctolagus cuniculus). A total of 73% of the specimens were positive, most of them contained 1000–10,000 oocysts per gram. Mixed infections with three Eimeria species were common. Eimeria perforans and E. media occurred most frequently, E. magna, E. coecicola and E. irresidua were less common and E. flavescens and E. intestinalis were relatively rare.     

A Comparison of Spontaneous and Odor-induced Chin Marking in Male and Female Domestic Rabbits (Oryctolagus cuniculus domestica)

Chin marking by the European rabbit (Oryctolagus cuniculus) is one of the classic but still little understood examples of mammalian chemical communication. To investigate whether the sexes differ in performance of this behavior, we compared the frequency of spontaneous chinning and chinning in response to the chin marks of conspecifics in 20 intact male and 20 intact female chinchilla-breed rabbits, and in five gonadectomized animals of each sex. Contrary to the expectation of greater chinning activity in males, no significant sex differences were found. Frequencies of spontaneous chinning were similar in the two sexes, large and stable individual differences were observed in both, chinning increased in both when marks from unfamiliar conspecifics were present, and both directed chin marks to objects marked by conspecifics more than to unmarked objects. Individual chinning frequencies correlated positively with urination but not defecation in both sexes, and spontaneous and odor-induced chinning were significantly reduced both in castrated and ovariectomized animals. The findings suggest that chinning is an equally significant part of the communication system of male and female rabbits and that its expression may be regulated by similar olfactory, hormonal, and social mechanisms.     

The ecological effects of the decline in Rabbits (Oryctolagus cuniculus L.) due to myxomatosis

The Rabbit (Oryctolagus cuniculus) population in the British Isles increased rapidly from the 1800s to 1950 due to climatic amelioration, predator reduction and agricultural changes. It became the major vertebrate pest of agriculture, causing an estimated £50 million in damage and lost production each year. Myxomatosis reached Britain in 1954-55 causing 99-9% mortality in some Rabbit populations and, carried by the mosquito and flea vectors, the disease spread rapidly. The consequent decline in the Rabbit population caused dramatic changes in agriculture and the native fauna and flora. It promoted woodland regeneration and increased grassland and cereal production; herb and grass height increased, flowering was noticeable and plant successions ensued. Some small legumes and annual plants became extinct locally and much floristically rich vegetation became dominated by a few grass species or shrubs. The increased grass growth probably promoted an increase in the number of many invertebrate species as well as in the vole (Microrus agrestis). Some species of insect became reduced in number and the Large Blue Butterfly (Maculinea arion) has become extinct (1979) since the decline of the ant (Myrmica spp.) fauna necessary to rear the butterfly larvae. Breeding sites for the Sand Lizard (Lacerta ugilis), Stone Curlew (Burhinus oedicnemus) and Wheatear (Oenanrhe oenanthe) have been reduced by habitat change. Immediately after myxomatosis many predator populations suffered from a lack of Rabbit prey with consequent poor breeding success, but those able to switch to voles, and other predators which are no longer taken in Rabbit trapping, have increased in numbers, e.g. Fox (Vulpes vulpes), Polecat (Mustela putorius), Short-eared Owl (Asio Barnmeus) and Kestrel (Falco tinnunculus). Others such as the Stoat (Mustela ermineu) and the Buzzard (Buteo buteo) declined immediately after myxomatosis through lack of prey and have recovered in nubers only slowly; the Peregrine falcon population has declined partly as a result of lack of open habitat. The breeding success of many predators was also reduced. Parasites of the Rabbit also declined; the flea (Spilopsyllus cuniculi), roundworms and tapeworms, as well as coccidiosis carried by Rabbits and particularly affecting young hares (Lepus europaeus) were all considered to be affected. Species such as the Pheasant Phasianus spp., the hare and the Roe Deer (Capreolus capreolus) increased their use of woodland habitat and/or benefited from the increased food available. Rats (Rartus nomegicus) appeared to decline following increased predation and loss of habitat. In Australia similar vegetational changes occurred in many areas after the introduction of myxomatosis and predators such as the Fox and Wedge-tailed Eagle (Aquila audax) were reduced by control measures following increased predation on sheep. Many bird and marsupial species were reduced in number after the loss of Rabbit prey or on becoming an alternative prey item. In Britain the loss of the fur industry has been outweighed economically by the increased agricultural production and reduced control and maintenance costs following myxomatosis. Since myxomatosis appeared Rabbit numbers have increased only slowly, probably because of increased predator pressure on low density populations and the periodic recurrence of the disease. Rabbit behaviour may have changed so that burrows are not used as much as in the past, Rabbit trapping has ceased and many habitats have been lost. Rabbit numbers could still reach moderate densities but a reversal of many of the ecological effects of my xomatosis is unlikely.     

Coccidiosis of the wild rabbit (Oryctolagus cuniculus) in France

In 1998-1999 a survey of coccidiosis in wild rabbits was carried out in six different localities in France. About five individuals were caught monthly in each locality and a total of 254 wild rabbits was examined. Ten species of Coccidio were identified: Eimeria perforans, E. flavescens, E. piriformis, E. exigua, E. media, E. magna, E. coecicola, E. stiedai, E. roobroucki, E. intestinalis. Intensity of infection in young individuals was higher than in adults. Intensity was highest in winter but, as there are no young rabbits in winter, in young individuals it was higher in spring and autumn than in summer. Intensities were higher in the northern rather than in southern localities. Ranking of prevalence was remarkably stable, in contrast to the variability of the parasitic load. The equilibrium between congeneric species of rabbit coccidia (stable prevalence rank, variable parasitic load) is thought to be probably the consequence of the opportunistic feeding habits of rabbits.     

Helminths of the wild rabbit (Oryctolagus cuniculus) in Macaronesia

Two hundred and four rabbits from 8 Macaronesian islands (Pico, San Jorge, San Miguel, Terceira, and Flores from Azores Archipelago; Tenerife and Alegranza from Canary Islands; and Madeira from Madeira Archipelago) were examined for helminth parasites between 1995 and 2000. Three species of cestodes, Taenia pisiformis (larvae), Andrya cuniculi, and Mosgovoyia ctenoides, and 5 species of nematodes, Trichuris leporis, Graphidium strigosum, Trichostrongylus retortaeformis, Passalurus ambiguus, and Dermatoxys hispaniensis, were identified. Only 3 species (M. ctenoides, T. retortaeformis, and P. ambiguus) were regularly distributed over the 3 archipelagos. Taenia pisiformis was not collected in Madeira, nor was A. cuniculi in the Azores and G. strigosum in the Canary Islands. Trichuris leporis and D. hispaniensis were only found in Madeira. Significant differences in the general prevalence of the nematodes G. strigosum and T. retortaeformis were detected between Azores and Madeira. The prevalence of T. retortaeformis differs significantly between the Azores and the Canaries and that of P. ambiguus was higher in Madeira than in Azores and Canaries. The helminth richness found in the wild rabbit in these Macaronesian archipelagos was very low compared with the Palearctic helminth fauna of this host. The wild rabbit was introduced from the Iberian Peninsula into different Macaronesian islands. Helminths introduced with Oryctolagus cuniculus into these islands also are commonly found in Iberian wild rabbits, which are excellent colonizers, as demonstrated in this study.     

Transferrin (Tf) polymorphism in wild rabbit, Oryctolagus cuniculus

Evidence for two new alleles (TfC and TfD) at the transferrin locus (Tf) in wild rabbit, Oryctolagus cuniculus, is presented. Blood samples were collected in Continental Portugal (178 individuals), and in the Azores Islands of Terceira (52) and S. Miguel (59). The frequency of TfA, which is the only allele detected up to now in domestic rabbits, varied from 0.20 +/- 0.13 to 0.95 +/- 0.05 in the populations sampled in Continental Portugal. In the island populations sampled the frequency of TfA was greater than 0.8.     

Videofluorographic analysis of tongue movement in the rabbit (Oryctolagus cuniculus)

The movement of the entire tongue and intermolar eminence during mastication is described in the domestic rabbit (Oryctolagus cuniculus). Tongue movement and jaw position were analyzed videofluorographically from separate lateral and dorso-ventral views in six rabbits. Metallic markers were inserted into the tongue so that its movement was visible on the fluorographic image. Frame-by-frame analysis of the videofluorographic tape recordings demonstrates that tongue movement in all animals was identical in direction during each part of the chewing cycle. In the lateral view the forepart of the tongue moves down and forward during the opening stroke, whereas the intermolar eminence moves up and forward to appose the palate. During the closing stroke, as the tip of the tongue moves up and back, the intermolar eminence lowers from the palate and retracts. During the power stroke the forepart of the tongue is at its most elevated and retruded position, while the intermolar eminence is its lowest and most retruded. The dorso-ventral view showed that lateral movement of the tongue and mandible are highly synchronous. The intermolar eminence decreases in width during the power stroke, possibly twisting to place or keep food on the teeth. An anterior to posterior undulating movement of the entire tongue occurs throughout the chewing cycle. As the intermolar eminence elevates to appose the palate during the opening stroke, it may replace the bolus on the teeth on the chewing side. The intermolar eminence also appears to be twisting during the closing and power strokes to place or maintain food on the teeth.     

Seasonal variation in gut morphology in wild rabbits (Oryctolagus cuniculus)

It is shown experimentally that diet composition affected the sizes of several digestive organs in juvenile rabbits collected from the wild. Stomach weight, small intestine volume and colon length were larger in rabbits reared on diets higher in fibre. Small intestine weight, however, was lower.
Analysis of natural variation in wild adult rabbits showed that all digestive organs (except for the appendix) were larger in rabbits living on chalk soils than in those living on sand or clay. Seasonal variation was more marked in males than in females, probably because of the sexes' different breeding requirements. Thus most male digestive organs were smaller between December and June than at other times of year. Female digestive organs did not show this pattern, and were largest in May/June, when the demands of pregnancy and lactation are highest. However, food quality may have been important too. Food quality is probably highest in April, and most digestive organs were then smallest (both sexes). The dry weights of stomach and small intestine did not fit these patterns. Stomach weight increased with the presence of the nematode parasite Graphidium strigosum and small intestine and caecal volumes with the presence of cestodes. Numbers of nematodes (Trichostrongylus retortaeformis and Passalurus ambiguus) in the caecum or colon, however, had no effects on organ sizes.
Data are presented on variation in intensity and prevalence of these helminth parasites with season and soil type.     

The Maturation of the Ovary in Wild Rabbits,Oryctolagus cuniculus,in South Sweden

In the ovaries of wild yearling rabbits the histologic changes occurring between September and March were determined and related to age and season. It was found that a considerable part of the ovarian development is characterized by the growth of follicles which soon become atretic and form interstitial gland tissue. The ovarian development up to a “sub-ovulatory” stage may be completed in the autumn in rabbits born early in the season, and later in those born late, so that by mid-winter they are all in this stage. No ovulation was found in rabbits in the early stages of development, and it is suggested that the presence of interstitial tissue is essential for full reproductive capacity.     

Heterogeneity of Es-1 esterases in the rabbit (Oryctolagus cuniculus)

Analysis of the Es-1 system in the rabbit with polyacrylamide gel electrophoresis (PAGE) revealed a high degree of individual variation. In the liver the number of esterase bands found in the Es-1 region of the gels ranged from 2 to 16. The results indicate that one locus with three alleles is responsible for all of the esterase bands in the Es-1 region. The most plausible explanation for the observed heterogeneity is that each of the alleles codes for a protein (MW 65,000±2000) that is changed by posttranslational modifications, thus giving rise to two to five monomeric enzymes with esterase activity. Polymerization of these monomers then results in 1–11 dimers. Based on similarities with mouse Es-9, chromosomal homology between rabbit Es-1 and mouse Es-9 is proposed.