Hematuria in rabbits

A nine year retrospective study of hematuria in 14 New Zealand White rabbits was conducted to classify possible etiologies of this clinical finding. Physical examination, laboratory tests, radiography and postmortem examination were utilized in most cases to verify the presence of hematuria and to determine its etiology. Uterine adenocarcinoma was diagnosed in two rabbits. Three rabbits had uterine polyps with hemorrhage. Renal infarction with hemorrhage was diagnosed in three rabbits. Urolithiasis with secondary urethral obstruction and hemorrhagic cystitis was identified as the cause of hematuria in four rabbits. Other causes of hematuria included chronic cystitis, disseminated intravascular coagulation, bladder polyps and pyelonephritis. Hematuria of undetermined origin was observed in one rabbit. This last [corrected] case was negative for both blood and porphyrin in the urine, but positive for excess levels of urobilin, the oxidative product of urobilinogen. This case illustrates that hyperpigmented urine should be a rule out in all cases of suspected hematuria in rabbits.     

Coronary chemoreceptors in rabbits

Position and structure of the coronary ++chemoreceptor (CH) have been studied in 40 Chinchilla rabbits by means of neurohistological and histochemical methods. The CH is situated in the adventitia of the left coronary artery. The CH together with chromaffin cells includes blood vessels, small nervous fasciculi and connective tissue. According to luminescent intensity 2 groups of cells are distinguished. Two types of CH cells are revealed morphometrically, they differ in their size. Metachromasia at staining with toluidine++ blue demonstrates presence of serotonin in the CH. A possible role of the CH in pathogenesis of a sudden death is considered.     

Monocyte kinetics in rabbits

Previous studies of monocytes isolated from peripheral blood have suggested that the lung sequesters these cells and has an important role in monocyte kinetics. However, the lung also provides the first capillary bed encountered by these cells after intravenous injection. A major criticism of the previous reports is that the behavior of monocytes in the lung may be altered as a result of the isolation procedure. The present study addresses this question by comparing the distribution of isolated monocytes (87% pure) in various organs 10 min after they were injected into either the central venous or the arterial circulation. The data show that the extraction of monocytes on the first passage through the lung after intravenous injection was 86.5 +/- 1.5%. After the monocytes had circulated for 10 min, the lungs contained 35.5 +/- 2.5% of the cells after intravenous injection and 29.7 +/- 2.2% after intra-arterial injection (P greater than 0.05). The lung-to-blood recovery ratio after either intravenous or intra-arterial injection showed that the lung contained a marginating pool of monocytes that was five to seven times the size of the circulating pool. The retention of monocytes in a region of the lung was proportional to the regional erythrocyte transit time. The half-life of the radiolabeled monocytes in the circulation was approximately 25 h. We conclude that the lung contains a marginating pool of monocytes and speculate that they concentrate there in preparation for migration into the interstitium and air space of the lung.     

Enterotoxemia in rabbits.

The presence of Clostridium perfringens Type E iota toxin was confirmed from the cecal contents of 23 of 46 rabbits which died of enteritis complex. The most consistent lesions observed were hemorrhage and edema in the cecum. Rabbit toxicity tests showed the toxic cecal contents were lethal for young rabbits unless incubated with Clostridium perfringens Type E antiserum.     

Intraoral examination in rabbits

Dental examination should be included in all physical examinations of rabbits because they have continuously growing teeth and are predisposed to dental disease. This column describes the procedure and equipment used for oral examination in rabbits.     

Alveolar differentiation in rabbits

Lung tissue of the white New Zealand rabbit was examined by transmission and scanning electron microscopy from the 23rd to the 30th day post conception (p.c.). The following results were obtained: 1. About day 23 p.c., when the development of capillaries increases, the "canalicular period" starts. This is followed by the "terminal sac period" characterized by the beginning of alveolarisation. On day 28 p.c. typical alveoles can be found. 2. The Pneumoplast is the stem cell of the pneumocyte type I as well as type II. They differentiate parallel in either one or the other. This stem cell of the entodermal origin has a single cilium. During the period of single cilia growth the cell is not mitotic. 3. The maturation of the lamellar body, typical of the pneumocyte type II, can be accomplished in a direct as well as in a indirect way of synthesis. Transitions between both are possible. 4. The most important factors of differentiation are collagenic induction substances beside nerval and humoral factors. Those humoral factors can be transported easier into the cells with advancing capillarisation as a result of the shortened distance of diffusion.     

Cyclosporine toxicity in rabbits

Rabbits treated with an immunosuppressive dose of cyclosporine for a prolonged period of time developed a clinically distinct toxic syndrome characterized by wasting, loss of weight, reduced food and water consumption and reduced movement. Ultimately 74 of 153 animals died within 60 days of treatment with a distended stomach and intestines full of dry undigested food. The syndrome was dose dependent but seemed unrelated to the route of administration. It occurred in two strains and two different colonies. No infectious agent was implicated. Histological examination and a variety of laboratory tests did not elucidate the syndrome. It could not be prevented by drugs that increased bowel movement or gastric emptying and was more pronounced in animals given additional indomethacin. Reduction of cyclosporine dose reduced toxicity but at the expense of reduced immunosuppression. We were unable to define a therapeutic non-toxic range by serial determination of cyclosporine blood concentrations. This highlights the difficulty in obtaining a therapeutic dosage level in rabbits on long-term cyclosporine immunosuppression.     

Lung mechanics in papain-treated rabbits

To further investigate the effects of airway cartilage softening on static and dynamic lung mechanics, 11 rabbits were treated with 100 mg/kg iv papain, whereas 9 control animals received no pretreatment. Lung mechanics were studied 24 h after papain injection. There was no significant difference in lung volumes, lung pressure-volume curves, or chest wall compliance. Papain-treated rabbits showed increased lung resistance: 91 +/- 63 vs. 39 +/- 22 cmH2O X l-1 X s (mean +/- SD; P less than 0.05), decreased maximal expiratory flows at all lung volumes, and preserved density dependence of maximal expiratory flows. We conclude that increased airway wall compliance is probably the mechanism that limited maximal expiratory flow in this animal model. In addition the increased lung resistance suggests that airway cartilage plays a role in the regulation of airway caliber during quiet tidal breathing.