Endocrinopathy and Aging in Ferrets

Ferrets have become more popular as household pets and as animal models in biomedical research in the past 2 decades. The average life span of ferrets is about 5-11 years with onset of geriatric diseases between 3-4 years including endocrinopathies, neoplasia, gastrointestinal diseases, cardiomyopathy, splenomegaly, renal diseases, dental diseases, and cataract. Endocrinopathies are the most common noninfectious disease affecting middle-aged and older ferrets. Spontaneous neoplasms affecting the endocrine system of ferrets appear to be increasing in prevalence with a preponderance toward proliferative lesions in the adrenal cortex and pancreatic islet cells. Diet, gonadectomy, and genetics may predispose ferrets to an increased incidence of these endocrinopathies. These functional proliferative lesions cause hypersecretion of hormones that alter the physiology and metabolism of the affected ferrets resulting in a wide range of clinical manifestations. However, there is an apparent dearth of information available in the literature about the causal relationship between aging and neoplasia in ferrets. This review provides a comprehensive overview of the anatomy and physiology of endocrine organs, disease incidence, age at diagnosis, clinical signs, pathology, and molecular markers available for diagnosis of various endocrine disorders in ferrets.

Staphylococcal meningoencephalitis, nematodiasis, and typhlocolitis in a squirrel monkey (Saimiri sciureus)

BACKGROUND

Seizures were observed in a 16-year old male Guyanese squirrel monkey with a history of inappetence and weakness.

METHODS AND RESULTS

Complete blood count, biochemical profile, and urinalysis indicated systemic disease. Nematode larvae were detected in the feces. Cerebrospinal fluid (CSF) analysis revealed leukocytes and gram-positive cocci. Staphylococcus aureus was isolated from the CSF. Histopathological evaluation revealed systemic lesions with inflammation and nematodes in the small and large intestine.

CONCLUSION

This is the first report describing spontaneous staphylococcal CNS infection in a squirrel monkey.

Failure of surface ring mutant strains of Helicobacter mustelae to persistently infect the ferret stomach

Helicobacter mustelae, the gastric pathogen of ferrets, produces an array of surface ring structures which have not been described for any other member of the genus Helicobacter, including H. pylori. The unique ring structures are composed of a protein named Hsr. To investigate whether the Hsr rings are important for colonization of the ferret stomach, ferrets specific pathogen free for H. mustelae were inoculated with an Hsr-deficient mutant strain or the wild-type H. mustelae strain. Quantitative cultures from antral biopsy specimens obtained at 3, 6, and 9 weeks postinoculation demonstrated no significant difference in the levels of bacteria in the ferrets that received the Hsr-negative strain and the ferrets infected with the parent strain. However, when the ferrets were biopsied at 12 and 15 weeks and necropsied at 18 weeks after infection, the levels of bacteria of the Hsr-negative strain in the stomach antrum were significantly reduced. This decline contrasted the robust antral colonization by the wild-type strain. The Hsr-negative strain did not efficiently colonize the gastric body of the study ferrets. Histological examination at 18 weeks postinoculation revealed minimal gastric inflammation in the animals that received the mutant H. mustelae strain, a finding consistent with its waning infection status, whereas lesions characteristic of helicobacter infection were present in ferrets infected with the wild-type strain. Scant colonization by the Hsr-negative H. mustelae strain at the end of the 18-week study, despite initial successful colonization, indicates an inability of the mutant to persist, perhaps due to a specific host response.

The normal upper gastrointestinal examination in the ferret

Upper gastrointestinal examinations were performed in 11 unsedated ferrets and 4 ferrets sedated with ketamine and diazepam. Each animal received a 8-13 mL/kg body weight dosage of barium liquid (30% weight:volume). Radiographs were made immediately and at 5, 10, 20, 40, 60, 90, 120 and 150 min (mins) after the barium was administered. Gastric emptying began immediately. Mean total gastric emptying was longer in sedated ferrets (130 +/- 40 min versus 75 +/- 54 min); however, this difference was not statistically significant (p = 0.18). Small intestinal transit time was less than 2 h in all ferrets. The barium-filled small bowel was best visualized on the 20- and 40-min radiographs and did not exceed 5-7 mm in width. Flocculation of barium in the small intestine and adherence of barium to the stomach mucosa was seen in almost all animals. The longitudinal colonic mucosal folds in the colon were well visualized in the normal upper gastrointestinal study and aided in distinguishing small intestine from large intestine. The use of ketamine and diazepam sedation did not significantly affect the parameters evaluated in the upper gastrointestinal study series.

Isolation and characterization of Corynebacterium ulcerans from cephalic implants in macaques

To determine the prevalence of colonization by Corynebacterium ulcerans, we cultured samples from the cephalic implant-skin margin and pharynx of 26 rhesus macaques and one pig-tailed macaque. All but one of the samples from the cephalic implants yielded a mixed population of bacteria. C. ulcerans grew from the cephalic implants in 56% and from the pharynx in 3% of the implanted animals. We screened nine of these isolates for diphtheria toxin (DT) and phospholipase D (PLD). Polymerase chain reactions (PCR) failed to identify DT in any of the tested isolates, which also lacked DT activity in Elek tests. However, all nine isolates tested had PLD toxin activity as determined by conjoint hemolysis on sheep blood agar plates in the presence of equi factor (Rhodococcus equi). In addition, PCR assays and Southern blot hybridization confirmed the presence of pld in the isolates. The role of the PLD toxin in promoting colonization of cephalic implants by C. ulcerans is unknown. We found C. ulcerans to be a frequent contaminant of the cephalic implant-skin margin. Further studies are necessary to investigate the relative clinical importance of this organism and the efficacy of various implant maintenance protocols in preventing infection.

Helicobacter pylori gastritis in cats with long-term natural infection as a model of human disease

A natural infection with Helicobacter pylori (H. pylori) in domestic cats (Felis cattus) less than 2 years of age has been well described in a closed colony of animals. Six cats from this colony that were serially evaluated by culture, polymerase chain reaction, and light and electron microscopy for a period of 3 years demonstrated persistent gastric colonization with a single cag(-) vac(+) strain of H. pylori. In these cats, as well as five other 5- to 6-year-old cats that were examined, a long-term infection resulted in chronic diffuse lymphofollicular atrophic gastritis with areas of mucosal dysplasia in the antrum and predominantly midsuperficial gastritis in the body and cardia. Topographically, the distribution of lesions was similar in both young and older cats and closely resembled that found in humans, with the most severe changes occurring in the gastric antrum. Few granulocytes and no significant elevation in mast cells were seen in older H. pylori-infected cats compared with uninfected controls; however, marked increases in interepithelial globule leukocytes and numerous active mucosal lymphoid follicles were present in infected animals. Indices of gastritis were significantly greater in older infected cats when compared with uninfected controls and younger cats (P < 0.05). The antral cell proliferation index of infected older cats was significantly (P = 0.021) greater than that of uninfected controls. Apoptotic indices of the gastric antrum and body of infected cats were significantly (P = 0.01) increased versus controls. Chronic infection with H. pylori in cats shares many features of long-term H. pylori infection in humans, including the development of preneoplastic processes. This similarity provides useful, comparative insights into host-pathogen interactions.

A conscious sheep model for the examination of arterial and cardiopulmonary baroreceptors in the dynamic closed-loop control of Total Peripheral Resistance

In this study we designed and employed a novel experimental animal model for the examination of arterial and cardiopulmonary baroreceptors in the dynamic closed-loop short-term cardiovascular control of total peripheral resistance, and applied system identification to the analysis of fluctuations in mean arterial pressure, right atrial transmural pressure, and Total Peripheral Resistance to characterize quantitatively the physiologic mechanisms responsible for the couplings between these variables. For this purpose, conscious sheep were used; where both types of baroreceptors were exposed simultaneously to random independent beat pressure variations over a small range around their operating points (via atrial pacing and occlusion of the inferior vena cava), while total peripheral resistance was measured. Subsequently, system identification was applied to the analysis of beat-to-beat fluctuations in the measured signals.

Ranitidine bismuth citrate and clarithromycin, alone or in combination, for eradication of Helicobacter mustelae infection in ferrets

OBJECTIVE

To determine whether ranitidine bismuth citrate, clarithromycin, or a combination of ranitidine bismuth citrate and clarithromycin would be efficacious in eradication of Helicobacter mustelae infection in ferrets.

ANIMALS

60 seven-month-old ferrets.

PROCEDURE

To determine dosages of clarithromycin and ranitidine bismuth citrate that would suppress growth of, but not eradicate infection with, H mustelae, ferrets (n = 6/group) were treated p.o. with clarithromycin or ranitidine bismuth citrate at various dosages. Efficacy of treatment was then determined by treating ferrets with clarithromycin alone, ranitidine bismuth citrate alone, or clarithromycin and ranitidine bismuth citrate. Gastric biopsy specimens were obtained before, during, and at various times after treatment and submitted for quantitative bacterial culture and histologic evaluation. Minimum concentrations of clarithromycin that inhibited 90% of the growth of isolates obtained before and after treatment were determined.

RESULTS

Dosages of clarithromycin and ranitidine bismuth citrate that suppressed growth of H mustelae were 12.5 and 24 mg/kg of body weight, p.o., every 8 hours, respectively. Infection was not eradicated in ferrets treated with ranitidine bismuth citrate alone but was eradicated in all 6 ferrets treated with clarithromycin and ranitidine bismuth citrate and in 4 of 6 treated with clarithromycin alone. A decrease in susceptibility to clarithromycin was detected for H mustelae isolates obtained after treatment. Mild or moderate antral gastritis was observed even in ferrets from which infection was eradicated.

CONCLUSIONS AND CLINICAL RELEVANCE

A combination of ranitidine bismuth citrate and clarithromycin was efficacious in eradicating H mustelae infection from ferrets.

Pregnancy toxemia in the European ferret (Mustela putorius furo)

BACKGROUND AND OBJECTIVE

Pregnancy toxemia may lead to appreciable mortality among jills and their offspring. The objective of this report was to increase awareness of the disease, its likely cause, and practical prevention and treatment measures.

METHODS

Ten cases of pregnancy toxemia were evaluated. Jills were in late gestation (mean, 38 days; range, 34 to 42 days) and had large litters (mean, 11.5 kits; range, 7 to 15 kits).

RESULTS

The most common clinical signs of disease were lethargy, inappetence, dehydration, and excess shedding. Hematologic and clinical biochemical abnormalities included anemia (4 of 8 jills tested), hypoproteinemia (5 of 7), azotemia (7 of 7), hypocalcemia (5 of 6), hyperbilirubinemia (3 of 3), and high liver enzyme activities (6 of 6). Two jills were found dead; two jills were euthanized, six received supportive treatment, and cesarean section was performed on five. The three jills that survived tended to have less pronounced azotemia, hypoproteinemia, and liver enzyme activity increases and were not anemic. Hepatic lipidosis was observed grossly in all jills that died and was confirmed by histologic examination in four jills.

CONCLUSIONS

Pregnancy toxemia in ferrets resembles metabolic diseases in several other animal species and requires aggressive treatment, including supportive care, nutritional supplementation, and cesarean section. Maintaining adequate nutrition and avoiding stress late in gestation may prevent the disease.

Cardiovascular pathology possibly associated with ketamine/xylazine anesthesia in Dutch belted rabbits

BACKGROUND AND PURPOSE

After myocardial necrosis and fibrosis was observed in five rabbits which had been anesthetized a variable number of times, the potential relationship of these lesions and anesthesia was evaluated in 35 other rabbits.

METHODS

Anesthesia was induced by intramuscular administration of ketamine and xylazine followed by infusion of lactated Ringer's solution also containing ketamine and xylazine. Group A rabbits (n = 9) were subjected to multiple anesthesias and were evaluated by echocardiography, thoracic radiography, electrocardiography, determination of serum coronavirus titer, vitamin E concentration, and complete necropsy. Prior to a single acute procedure followed by necropsy, group B rabbits (n = 11) were evaluated by echocardiography only. Group C rabbits (n = 10) had never been anesthetized and were necropsied after euthanasia. Group D rabbits (n = 5) had intermediate anesthesia exposure history and were evaluated by echocardiography only. Myocardial fibrosis was scored semi-quantitatively on a scale of 0 to 4.

RESULTS

Canine coronavirus test results were negative; hypovitaminosis E was evident, and fibrosis scores were significantly increased in group A, compared with group B or group C, rabbits.

CONCLUSION

Etiologic differentials included alpha2-agonist-mediated coronary vasoconstriction with associated myocardial hypoperfusion, hypovitaminosis E and free radical injury, and other anesthetic-induced physiologic trespass.

Experimental infection in cats with a cagA+ human isolate of Helicobacter pylori

BACKGROUND

Helicobacter pylori has been cultured from the inflamed gastric mucosa of naturally and experimentally-infected cats. The lesions in the H. pylori-infected cat stomach mimic many of the features seen in human stomachs infected with H. pylori. This study sought to determine whether H. pylori-negative, specific pathogen-free cats with normal gastric mucosa were susceptible to colonization with a human cagA+ strain of H. pylori, and whether gastritis developed after infections.

METHODS

Four H. pylori-negative cats treated with cimetidine were orally dosed 3 times at 2-day intervals with 3 ml (1.5 x 108 CFU/ml) of H. pylori.

RESULTS

All experimentally-infected cats became persistently colonized as determined by H. pylori isolation from gastric tissue by culture at 12 weeks, and all 4 cats were found positive by PCR during serial gastric biopsies and necropsy at 15 weeks postinoculation. The 2 control cats did not have H. pylori isolated, nor was gastric tissue positive by PCR. The H. pylori isolated from the 4 experimentally-infected cats had RFLP patterns specific for the flaA gene identical to those of the inoculating strain. All 4 H. pylori-infected cats had multifocal gastritis, consisting of lymphoid aggregates plus multiple large lymphoid nodules. In the control cats, one cat had a few focal lymphocytic aggregates in the body submucosa, whereas the second cat had normal gastric mucosa.

CONCLUSION

Human cagA+ H. pylori readily colonized the cat stomach and produced a persistent gastritis. The findings demonstrate the utility of the cat to study H. pylori induced pathogenesis.

Helicobacter bilis/Helicobacter rodentium co-infection associated with diarrhea in a colony of scid mice

An outbreak of diarrhea spanning 3 months occurred in a breeding colony of scid/Trp53 knockout mice. Approximately a third of the 150 mice were clinically affected, with signs ranging from mucoid or watery diarrhea to severe hemorrhagic diarrhea with mortality. Helicobacter bilis and the newly recognized urease-negative organism H. rodentium were isolated from microaerobic culture of feces or cecal specimens from affected mice. Dual infection with H. bilis and H. rodentium were confirmed by culture and polymerase chain reaction (PCR) in several animals. Both Helicobacter species rapidly colonized immunocompetent sentinel mice exposed to bedding from cages containing affected mice, but the sentinel remained asymptomatic. Mice with diarrhea had multifocal to segmental proliferative typhlitis, colitis, and proctitis. Several affected mice had multifocal mucosal necrosis with a few focal ulcers in the cecum, colon, and rectum. Mice with diarrhea were treated with antibiotic food wafers (1.5 mg of amoxicillin, 0.69 mg of metronidazole, and 0.185 mg of bismuth/mouse per day) previously shown to eradicate H. hepaticus in immunocompetent mice. Antibiotic treatment resulted in resolution of diarrhea, but not eradication of H. bilis and H. rodentium; mice continued to have positive PCR results after a 2-week treatment regimen, and clinical signs of diarrhea returned in some mice when treatment was suspended. To the authors' knowledge, this is the first report of natural infection with either H. bilis and/or H. rodentium causing acute diarrheal disease and suggests that H. bilis and/or H. rodentium can be an important pathogen for scid mice.

Distribution of technetium 99m-labeled red blood cells during isoflurane anesthesia in ferrets

OBJECTIVE

To address the physiologic mechanism of isoflurane-associated reduction in hematologic variables in ferrets.

ANIMALS

6 young adult female ferrets.

PROCEDURE

Distribution of 99mTc-labeled autologous erythrocytes was measured by serial in vivo imaging. Data were recorded in 4 ferrets, using a gamma camera, immediately prior to anesthesia, 15 minutes after 2% isoflurane anesthesia in O2 via endotracheal tube, 1 minute prior to and throughout a 10-minute phenylephrine infusion, 20 and 40 minutes after termination of the phenylephrine infusion, and 45 minutes after termination of anesthesia. Blood indices were also measured at times that paralleled those for imaging. One ferret served as a conscious control (no anesthetic administration), and another as an isoflurane control (no phenylephrine administration).

RESULTS

In ferrets under anesthesia, splenic radioactivity increased from baseline of 10.2 +/- 2.0% to 38.4 +/- 3.2% (mean +/- SEM; P < 0.05) of the injected dose. Splenic radioactivity decreased to 13.4 +/- 3.8% of the injected dose during phenylephrine infusion and to near baseline for the recovery image. Splenic radioactivity in the conscious control remained constant throughout the study, whereas that of the anesthetized control was persistently increased throughout administration of isoflurane. Percentage reduction of the 15-minute sample values, compared with baseline values for all hematologic indices, was: RBC count, 33% (P < 0.05); hemoglobin concentration, 34% (P < 0.05); hematocrit, 35% (P < 0.05); and plasma protein concentration, 20% (P < 0.05). All RBC variables returned to within 7 to 14% of baseline by 45 minutes after termination of anesthesia.

CONCLUSION

Isoflurane anesthesia causes splenic sequestration of RBC in ferrets that is partially reversed by phenylephrine infusion or termination of anesthesia. Thus, investigators and clinicians should be cautious when interpreting hematologic findings in isoflurane-anesthetized ferrets, and accordingly, fluid treatment and transfusion should be planned.

Infection of the ferret stomach by isogenic flagellar mutant strains of Helicobacter mustelae

Helicobacter mustelae, like Helicobacter pylori, possesses two flagellin proteins, FlaA and FlaB. Isogenic mutant strains of H. mustelae have been constructed by disruption of the flaA or flaB gene with a kanamycin resistance cassette or by introduction of both a kanamycin and a chloramphenicol resistance gene to produce a double mutant. To determine whether one or both flagellin proteins are necessary for colonization and persistence of infection with H. mustelae, 19 ferrets, specific pathogen free for H. mustelae, were given either the HMF1 flaA::km (weakly motile), ATCC 43772 flaB::km (moderately motile), or HMF1 flaA::cat flaB::km (non-motile) mutant strain, the wild-type parent strains, or sterile broth. Gastric tissue samples were obtained during sequential gastric biopsies beginning at 3 weeks postinoculation and ending at necropsy at 3 months postinoculation. H. mustelae infection status was determined by culture, histology, and serology. The wild-type parent strains of H. mustelae infected all ferrets at all time points. The double-mutant strain was unable to colonize; the flaA and flaB single-mutant strains were able to initially colonize at a low level and establish persistent infection with increasing numbers of organisms over time. The severity of gastritis produced by infection with these strains of H. mustelae correlated with the number of organisms present in the gastric mucosa. Flagellar motility is an important virulence factor for colonization and pathogenesis in the H. mustelae ferret model.

Measurement of flow rates through aortic branches in the anesthetized rabbit

The volumetric flow rates, mean and pulsatile, in the aorta and its major branches were measured in nonfed, anesthetized rabbits, using a transit time Doppler ultrasonic flowmeter. Anesthesia was maintained with isoflurane, and a vasodilator was applied topically during the measurements to avoid introducing additional flow resistance due to vasoconstriction. The cranial mesenteric and celiac arteries received the bulk of the aortic flow, (mean +/- SD) 29.5 +/- 6.6% and 23.3 +/- 5.8%, respectively, for mean flow. The brachiocephalic artery received as much as 14.7 +/- 3.2%, while each of the other branches received a considerably smaller fraction: 7.1 +/- 2.5% for the left subclavian artery, 6.2 +/- 2.6% and 5.1 +/- 2.2%, respectively, for the right and left renal arteries, and 6.0 +/- 2.5% for each of the two iliac arteries. Flow divisions were nearly the same in paired vessels. Peak pulsatile flow divisions were similar to their steady flow counterparts in the brachiocephalic, left subclavian, celiac, and cranial mesenteric arteries, but were smaller in the renal and iliac arteries, although the difference was not statistically significant. Reverse flow from one or more of the branches back into the aorta occurred in diastole in seven of eight rabbits studied.

Microbiologic, radiographic, and anatomic study of the nasolacrimal duct apparatus in the rabbit (Oryctolagus cuniculus)

This study was motivated by the sporadic observation of epiphora in two male rabbits. The epiphora was unilateral and not associated with conjunctivitis or Pasteurella infection. To characterize the cause of epiphora, we studied 15 specific-pathogen-free New Zealand White rabbits. This study group was composed of the two affected males, four unaffected males, and nine unaffected females. Clinical evaluation consisted of bacterial culture of conjunctival specimens, examination of conjunctival scrapings for chlamydial inclusions, culture and cytologic examination of specimens from the nasolacrimal duct, plain and contrast radiography, latex casting, histologic examination, and the Schirmer tear test. Important differences found in the rabbits with epiphora included an opalescent, gritty, nasolacrimal duct flush fluid and marked unilateral dilatation of the duct proximal to a dorsal flexure at the caudal limit of the incisor tooth root. The flush solution from one affected rabbit cleared with ether, suggesting the presence of triglycerides or cholesterol. The organisms most commonly isolated from the conjunctiva were Moraxella sp., Oligella urethralis, Staphylococcus aureus, coagulase-negative Staphylococcus sp., and Streptococcus viridans. The organisms most commonly isolated from the nasolacrimal duct flush fluid were Moraxella sp., S. viridans, and Neisseria sp. Culture of the nasolacrimal duct flush fluid yielded microorganisms more consistently than did culture of the conjunctival specimens. All microorganisms isolated from affected rabbits also were isolated from unaffected rabbits. There was no apparent contribution of microorganisms to the development of epiphora, and Schirmer tear test results for affected animals were within the range seen in unaffected animals. Occlusion of the nasolacrimal duct was presumed to be attributable to fat droplets. This study augments the existing literature and represents the first report of anomalous nasolacrimal duct anatomic features in the rabbit.

Inability of an isogenic urease-negative mutant stain of Helicobacter mustelae to colonize the ferret stomach

Eight ferrets specific-pathogen-free for Helicobacter mustelae were given, per dose, approximately 3.0 x 10(7) CFU of either the wild-type parent strain of H. mustelae (NCTC 12032) (two ferrets) the isogenic urease-negative mutant strain of H. mustelae (10::Tn3Km) (four ferrets), or sterile culture broth (two ferrets). Infection status was monitored by endoscopic gastric biopsy for urease activity, histopathology, and culture and by serology at 3, 6, 10, and 21 weeks. All ferrets were necropsied at 25 weeks. Both negative control ferrets remained uninfected, both ferrets receiving the H. mustelae wild-type parent strain became infected after two doses of the organism, and all four ferrets given two doses of the isogenic urease-negative mutant strain of H. mustelae remained uninfected throughout the 6-month study. Histopathology correlated with infection status. H. mustelae-infected ferrets exhibited diffuse mononuclear inflammation in the subglandular region and the lamina propria of the gastric mucosa, while uninfected ferrets showed no or minimal inflammation. These results suggest that urease activity is essential for colonization of the ferret stomach by H. mustelae.

Vitamin E enhances the lymphatic transport of beta-carotene and its conversion to vitamin A in the ferret

BACKGROUND/AIMS

beta-Carotene and alpha-tocopherol may have either antagonistic or synergistic effects on each other's absorption and metabolism. The effects of both physiological and pharmacological concentrations of alpha-tocopherol on the absorption and metabolism of beta-carotene in ferret intestine were determined.

METHODS

A high concentration of beta-carotene was perfused through the upper portion of the small intestine of ferrets in vivo with varying levels of alpha-tocopherol. The effluent of a mesenteric lymph duct cannulation, the intestinal mucosal scraping, and portal vein blood were sampled and analyzed by high-performance liquid chromatography.

RESULTS

The lymphatic transport of beta-carotene was enhanced 4-fold by alpha-tocopherol at a physiological dose and 12-21-fold at a pharmacological dose. The lymphatic transport of alpha-tocopherol was linearly (r = 0.8; P < 0.05) related to the luminal alpha-tocopherol concentration even in the presence of a high concentration of beta-carotene. Furthermore, alpha-tocopherol increased the conversion of beta-carotene into retinol in the intestine in a dose-dependent manner.

CONCLUSIONS

alpha-Tocopherol has a positive effect on the intestinal absorption of intact beta-carotene and may modulate the metabolic conversion of beta-carotene into retinoids.

Effect of isoflurane on hematologic variables in ferrets

Effects of isoflurane on the CBC in ferrets were studied. There was rapid decrease in all hematologic variables after induction of anesthesia. Percentage reductions in indices of the erythron (hematocrit, RBC count, hemoglobin concentration) exceeded those of plasma protein concentration and WBC count at the first postinduction time point. There was little additional decrease in these variables for the duration of anesthesia. The values had partially recovered to preanesthetic baseline at 45 minutes after anesthesia. Although these alterations appear to be well tolerated in healthy ferrets, care should be exercised when subjecting anemic, geriatric, or debilitated ferrets to isoflurane-induced anesthesia.

Evaluation of detomidine anesthetic combinations in the rabbit

Detomidine, a potent alpha 2-adrenergic receptor agonist, was chosen for study alone and in combination with ketamine with or without diazepam. Four regimens were evaluated: detomidine (150 micrograms/kg of body weight) alone (D); ketamine (35 mg/kg) and detomidine (150 micrograms/kg) (KD); ketamine (35 mg/kg) and high-dose detomidine (300 micrograms/kg) (KDh); and ketamine (35 mg/kg), diazepam (1 mg/kg), and detomidine (150 micrograms/kg) (KDD). The same six rabbits were anesthetized with each combination at weekly intervals. Atropine (0.04 mg/kg) was administered as a preanesthetic 5 min prior to test substance administration. All agents were administered IM, except for diazepam, which was administered IV. Heart and respiratory rates, mean arterial blood pressure, and arterial blood gas tensions were measured. Pedal, palpebral, and righting reflexes also were evaluated. Cardiopulmonary depression, as indicated by decrease in heart and respiratory rates, blood pH, PO2, and increase in PCO2, was observed in all groups. With the exception of heart rate, detomidine used alone caused the least depression of these parameters. Reflexes were consistently lost only after KDh and KDD administrations. The pedal reflex, used as an index of anesthetic depth, was lost in response to KDh and KDD for 56.7 +/- 11.6 and 43.8 +/- 7.4 min, respectively (mean +/- SEM). Three of the six rabbits were anorectic after KDh administration. Necropsy and histologic evaluation revealed myocardial necrosis and fibrosis in five animals. Due to the inconsistent reflex loss in response to KD and D and inappetance associated with KDh, these combinations were not considered safe or reliable.(ABSTRACT TRUNCATED AT 250 WORDS)

A technique for catheterization of the urinary bladder in the ferret

The technique of catheterization of the urinary bladder, an important clinical skill for the diagnosis of urinary tract disorders, has not been described for the ferret. The bladder was catheterized in 23 ferrets (10 intact females; 11 spayed females; and 2 intact males) using a 3 1/2 French, red rubber urethral catheter fitted with a steel wire stylet. Ferrets were anaesthetized with isoflurane or ketamine (30 mg/kg IM) and xylazine (3 mg/kg IM). Females were positioned in ventral recumbency with the rear quarters elevated by a rolled surgical towel. The urethra was catheterized by direct visualization of the external urethral orifice using a vaginal speculum. The orifice was approximately 1 cm cranial to the clitoral fossa on the ventral floor of the vestibule. Blind passage was used in several spayed females. In males, the distal end of the penis was exteriorized from the prepuce and the external urethral orifice cannulated without stylet. No difficulty was encountered in advancing the catheter past the os penis. This catheterization technique allows urinary tract access for urine collection, pneumocystography, contrast cystography, double contrast cystography, and urine output determination in pharmacologic studies or in critical care of debilitated animals.

Estimation of glomerular filtration rate and evaluation of renal function in ferrets (Mustela putorius furo)

Three methods of determining glomerular filtration rate (GFR) were performed in adult ferrets, 9 months to 7 years old. Endogenous creatinine clearance was determined, using serum and urine creatinine values obtained during 24- and 48-hour collection periods from 27 ferrets housed in metabolic cages. Creatinine and radiolabeled inulin were administered to 12 female ferrets by constant IV infusion during isoflurane-induced anesthesia. Serial 20-minute urine collections, together with serum samples obtained at the midpoint of urine collection, provided measures for clearance calculations of these substances. Mean +/- SD endogenous creatinine clearance in ferrets for metabolic cage collections was 2.50 +/- 0.93 ml/min/kg of body weight. There were no significant differences between the 24- and 48-hour clearance rates. Mean inulin clearance was 3.02 +/- 1.78, and mean exogenous creatinine clearance was 3.32 +/- 2.16 ml/min/kg. Analysis of variance, using least-squared means adjustment, did not yield any significant differences between inulin and exogenous creatinine clearance rates. Exogenous creatinine clearance-to-inulin clearance ratio was 0.99 +/- 0.46, and there was significant correlation between the 2 methods (r = 0.82, P = 0.0001). Significant body temperature effects on inulin or exogenous creatinine clearance were not found. Infused inulin clearance, the generally preferred method for GFR calculation in mammalian species, was significantly (P = 0.0069) higher in younger (3.65 ml/min/kg) vs older ferrets (2.29 ml/min/kg). Results of this study indicate that inulin clearance is an adequate measure of GFR in ferrets as it is in other species. Compared with inulin clearance, exogenous creatinine clearance also provides a reliable estimate of GFR in ferrets.

Estradiol-17 beta-secreting adrenocortical tumor in a ferret

Severe generalized alopecia and marked vulvar enlargement were observed in a 5-year-old spayed ferret with high serum estradiol concentrations. A neoplastic left adrenal gland was removed. Staining of the neoplastic cells for estradiol was demonstrated by use of immunohistochemistry. Clinical findings in this ferret were typical of adrenal-associated endocrinopathy, a syndrome characterized by increased secretion of adrenocortical hormones by hyperplastic or neoplastic adrenal glands.

An evaluation of three neuroleptanalgesic combinations in rabbits

In this study, novel combinations of analgesics and neuroleptics were used in the rabbit in an attempt to produce a surgical level of anesthesia. A commercially available mixture of fentanyl (0.06 mg/kg) and droperidol (3.0 mg/kg; F/D) was evaluated alone and in combination with either the benzodiazepine derivative, diazepam (2 mg/kg) or the alpha-2 adrenoceptor agonist, detomidine (20 micrograms/kg). Rabbits were anesthetized on consecutive weeks with one of the three regimens. Heart rate, respiratory rate, blood pressure, and arterial blood gases (pH, PCO2, PO2) were measured throughout each trial. The times of loss and return of palpebral, righting, and pedal reflexes were recorded. The addition of diazepam to the F/D combination caused marked prolongation of the duration of reflex loss for all reflexes. If the duration of reflex loss for F/D is considered to be 100%, then F/D plus diazepam (F/D/diazepam) prolonged the duration of reflex loss to 547% and 204% for righting and pedal reflex, respectively. The combination of F/D/diazepam produced significantly different results from those for either of the other combinations for righting reflex and palpebral reflex. The results for F/D/diazepam were also markedly different from F/D for pedal reflex, but were not significantly different from those for F/D/detomidine. Prolongation of the duration of reflex loss was more moderate with the addition of detomidine (148% and 174% for righting and pedal reflexes, respectively). Reflexes persisted in some rabbits for each anesthetic regimen. Palpebral reflex was preserved in one of the rabbits given F/D/diazepam, four of five rabbits given F/D, and in two rabbits given F/D/detomidine.(ABSTRACT TRUNCATED AT 250 WORDS)

Intestinal perfusion of beta-carotene in the ferret raises retinoic acid level in portal blood

To determine whether beta-carotene (beta-C) can serve as a source of intestinally-derived retinoic acid (RA), either 15,15'-[14C]beta-C or unlabeled beta-C was perfused through 30 cm jejunal segments of ferrets in vivo. Portal vein blood was sampled periodically via an indwelling catheter. RA was identified in portal blood by comparing retention times in HPLC, by UV absorption, and by derivatization (methylation) and subsequent GC-MS analysis. The RA concentration in the portal blood increased 3-fold with perfusion of beta-C (P < 0.05), and remained at 18 nmol/L during the perfusion of beta-C. The single peak of RA in HPLC was shown to consist of four separate peaks by GC-MS, which may be cis-trans isomers of RA. The concentration of RA in portal blood returned to the initial level (5 nmol/L) after a 2 h period of intestinal perfusion with 5% dextrose. Retinyl ester concentration in portal blood did not change before or after the perfusion, whereas retinol decreased significantly during the perfusion of beta-C. This study clearly indicates that a considerable quantity and number of polar metabolites, including RA, are formed from beta-C in the ferret intestine which are transported via the portal vein to the liver.

Functional islet cell tumor in six ferrets

Functional islet cell tumor was diagnosed in 6 ferrets. Prominent clinical signs included weight loss, hind limb weakness, ptyalism, and tremors. The diagnosis was made on the basis of 2 or more of the following methods and confirmed by histologic examination of biopsied tissue: hypoglycemia on routine serum biochemical analysis, clinical signs of hypoglycemia, simultaneous development of hypoglycemia (44 +/- 9.9 mg/dl; mean +/- SD), and hyperinsulinemia (58 +/- 18.4 microU/ml; mean +/- SD) after food was withheld for 4 hours. Surgical resection of affected tissue was associated with clinical improvement in all cases. Foci of metastasis were found in 1 ferret. Diazoxide was unsuccessful in controlling persistent postsurgical hypoglycemia in 2 ferrets. Additional functional islet cell tumors were identified in 5 of 6 ferrets at necropsy. Functional islet cell tumors are important neoplasms of older ferrets. Preventive health programs for ferrets > 3 years old should include monthly weight determinations and biannual CBC and serum biochemical analysis.

Intestinal uptake and lymphatic absorption of beta-carotene in ferrets: a model for human beta-carotene metabolism

To determine the appropriateness of the ferret as a model for human beta-carotene (beta-C) metabolism, we have perfused both 15,15'-beta-[14C]C and unlabeled beta-C through the upper 30-cm portion of the small intestine of ferrets in vivo. The effluents of a mesenteric lymph duct cannulation and a common bile duct cannulation, as well as portal vein blood periodically sampled via an indwelling catheter, were collected. Ten percent (9.5 +/- 0.06%) of the total administered beta-C was taken up by the intestine after a 4-h perfusion. Of the radioactivity taken up, 68.6 +/- 6.5% remained in the intestinal mucosa, 3.2 +/- 0.2% was recovered in the lymph, and 28.2 +/- 6.5% (calculated) was absorbed via the portal system. The total uptake/absorption of beta-C was 12.9 +/- 6.8 nmol.h-1.30 cm intestine-1. Large amounts of unchanged beta-C and relatively small amounts of both beta-apo-12'-carotenal and beta-apo-10'-carotenal were isolated in the intestinal mucosa after a 4-h perfusion with beta-C. Considerable amounts of metabolites more polar than retinol were formed and comprised 35% of the total radioactivity recovered in the intestinal mucosa. Polar metabolites were absorbed mostly into the portal venous system, whereas retinol and retinyl esters were absorbed mainly into the mesenteric lymph. Of the total absorbed radioactivity in lymph, 10 +/- 1.0% appeared as unchanged beta-C, with peak absorption occurring at 3 h after beginning the perfusion.(ABSTRACT TRUNCATED AT 250 WORDS)

Ketamine/xylazine/butorphanol: a new anesthetic combination for rabbits

Ketamine is often used in combination with tranquilizers to produce surgical anesthesia in rabbits. While generally effective, there is considerable variation in the depth and duration of anesthesia achieved with ketamine combinations. Butorphanol is a mixed agonist-antagonist opioid that is widely used in a variety of other species. In this study, the commonly used ketamine (35 mg/kg)/xylazine (5 mg/kg) combination is compared with ketamine (35 mg/kg)/xylazine (5 mg/kg)/butorphanol (0.1 mg/kg). Rabbits were anesthetized on consecutive weeks with one of the two regimens. Physiologic parameters including heart rate, respiratory rate, blood pressure and arterial blood gases (pH, PO2, PCO2) were measured throughout anesthesia. Loss of palpebral, pedal and righting reflexes were recorded and reflexes were subsequently evaluated. The addition of butorphanol prolonged reflex loss to 140% (X = 68 min +/- 20 SEM) of control for palpebral reflex; 506% (X = 52 min +/- 18 SEM) of control for pedal reflex; and 159% (X = 128 min +/- 21 SEM) of control for righting reflex. Addition of butorphanol to ketamine/xylazine resulted in mild alterations in the physiologic changes traditionally associated with this combination. Butorphanol can be safely added to the ketamine/xylazine combination in rabbits and results in moderate increases in the duration of reflex loss.

Cervical lymphadenitis in guinea pigs: infection via intact ocular and nasal mucosa by Streptococcus zooepidemicus

The traditional view regarding the pathogenesis of cervical lymphadenitis in guinea pigs is that Lancefield Group C Streptococcus gains access to cervical lymph nodes via an abraded oral mucosa. In this study, it is established that inoculation of intact nasal and conjunctival mucous membranes with Streptococcus zooepidemicus (Lancefield Group C) also can produce the disease. Weanling (SPF) guinea pigs (Cavia porcellus) were divided into two experimental groups of 10 and two control groups of four each. Guinea pigs from each group were individually housed in separate cubicles. Group I was inoculated with 0.05 ml of culture containing 2.8 x 10(7) CFU/ml of S. zooepidemicus into the conjunctiva of the left eye. Group II received a similar inoculum into the left nares. Control groups received 0.05 ml of TSB broth in the same sites. Five of ten guinea pigs in Group II died four to nine days postinoculation. Surviving guinea pigs were euthanatized at intervals between days 4-13 postinoculation. All guinea pigs were necropsied, cultured and examined for evidence of infection. S. zooepidemicus was recovered from 30/50 and 39/46 sites cultured from Groups I and II, respectively. Lymphadenitis was found in cervical lymph nodes from 8/10 guinea pigs in Group I and 10/10 in Group II. The conjunctival and nasal mucosa, therefore, represent potential sites of entry resulting in cervical lymphadenitis in guinea pigs.

A comparison of ketamine/xylazine and ketamine/xylazine/acepromazine anesthesia in the rabbit

Parenteral anesthetic combinations such as ketamine and xylazine have become the agents of choice for anesthesia in the rabbit, because they are effective, easily administered and inexpensive. A number of recent reports have recommended including acepromazine in this combination, but a critical evaluation of this combination in the rabbit has not been reported. Five adult New Zealand white rabbits were anesthetized intramuscularly with ketamine (35 mg/kg) and xylazine (5 mg/kg) with or without acepromazine (0.75 mg/kg). The study was conducted in a double blind fashion, where each rabbit was administered both combinations at a minimum of 7 day intervals. Physiologic parameters were evaluated including heart rate, respiratory rate, central arterial blood pressure, pedal, palpebral and postural reflex activity. The duration of general anesthesia, estimated by the time elapsed between the loss and return of the palpebral reflex, was greater (means = 99 +/- 20 minutes) when acepromazine was employed in the combination compared to (means = 77 +/- 5 minutes) when ketamine/xylazine were used alone. Mean central arterial blood pressure reached a lower level when acepromazine was utilized (means = 46 +/- 8 mm/Hg) than when it was not (means = 57 +/- 12 mm/Hg.). The addition of acepromazine in a ketamine/xylazine combination resulted in a 28% longer period of anesthesia, a 19% lower mean central arterial blood pressure and a 32% longer recovery of postural reflexes. The ketamine/xylazine/acepromazine combination is a useful regimen for normovolemic animals when anesthetic duration greater than that produced by ketamine/xylazine alone is required.

Seasonal correlations of specific leaf weight to net photosynthesis and dark respiration of apple leaves

Specific leaf weight (SLW), net photosynthesis (P n ), and dark respiration (R d ) of apple leaves were monitored for an entire growing season. Leaves were sampled from the canopy interior and periphery to provide a range of SLW. Leaf P n was linearly correlated with SLW until mid-August, when P n began to decline. During September the relationship between SLW and P n was a quadratic. Leaf R d and SLW were linearly correlated throughout the season. Leaf P n and R d were significantly correlated through most of the season, but the relationship was not always linear. Specific leaf weight appears to be a reliable index of the previous light environment of a leaf, but use to estimate P n is probably limited to the first half of the season, because of increased variation after mid-August.