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PubMed2003

Locations of neurons with respiratory-related activity in the ferret brainstem.

Previous transneuronal tracing studies conducted in the ferret revealed that a large population of neurons that provides inputs to diaphragm and abdominal motoneurons is located in the ventral magnocellular portion of the medial medullary reticular formation. These observations raise the possibility that the neural substrate underlying respiratory rhythmogenesis may be different in the ferret than in other species in which this circuitry has been explored. In the present study, systematic tracking was conducted through the ferret medulla to map the locations of neurons with activity related to the contractions of respiratory muscles. As in the cat, rat, and rabbit, neurons with respiratory-related discharges were distributed either lateral or ventrolateral to the solitary nucleus (dorsal respiratory group) or in the vicinity of nucleus retroambigualis, nucleus ambiguus and the retrofacial nucleus (ventral respiratory group). Although the general organization of respiratory group neurons appeared to be similar in the ferret to that in other mammals, a difference was that few expiratory neurons were located rostrally in the ventral respiratory group. These data suggest that the ventral magnocellular medullary reticular formation is not essential for respiratory rhythm generation, at least during quiet breathing, but may participate in regulating the excitability of respiratory motoneurons or in coordinating the contractions of respiratory muscles during nonrespiratory responses (e.g. coughing or emesis).

Abdominal Muscles↗
PubMed1993

Spontaneous neoplasia in the ferret (Mustela putorius furo).

Thirteen spontaneous tumours in ferrets from two laboratory breeding colonies are described, including two types not previously reported in this species, namely, uterine teratoma and neurilemmoma. The literature on tumours in laboratory and domestic ferrets is comprehensively reviewed from the first reported case in 1950. Only 20 cases were reported from 1950 to 1979, nearly all from laboratory or zoological collections. In the following 10 years more than 170 further cases were reported, about half of them in domestic pet ferrets. A review of the limited literature on tumours in related species reveals substantial incidences in black-footed ferrets and ranch mink allowed to live out their lifespan, and isolated cases in polecats and at least eight other species of Mustelidae.

Animals↗
PubMed2000

The role of 5-hydroxytryptamine3 and 5-hydroxytryptamine4 receptors in the regulation of gut motility in the ferret.

The role of 5-hydroxytryptamine (5-HT)3 and 5-HT4 receptors in the regulation of gut motility in the ferret was investigated. The selective 5-HT3 receptor antagonist ramosetron (1 - 10 microg/kg s.c.) prolonged the interval of gastric antral migrating motor complex, but had only slight effect on small intestinal and colonic motility in unfed animals. The selective 5-HT4 receptor antagonist SB 204070 did not affect motility throughout gut in unfed animals. Neither ramosetron nor SB 204070 affected the motility throughout gut in fed animals. In conclusion, neither 5-HT3 nor 5-HT4 receptors tonically regulate ferret gut motility except that 5-HT3 receptors have a key role in the occurrence of migrating motor complex specifically in the stomach. The role of 5-HT3 and 5-HT4 receptor system in the regulation of gut motility in ferrets is similar to that in other mammalian species studied, including humans. This similarity suggests that the ferret is a suitable model animal to study gut motor functions in humans.

Animals↗
PubMed1996

Tachykinin NK1 receptor antagonists act centrally to inhibit emesis induced by the chemotherapeutic agent cisplatin in ferrets.

These studies have compared the pharmacological profile of two non-peptide human type neurokinin1 (hNK1) receptor selective antagonists, L-741,671 and a quaternised compound L-743,310. In radioligand binding studies L-741,671 and L-743,310 had high affinity for ferret and cloned hNK1 receptors [Ki (nM) ferret 0.7 and 0.1; human 0.03 and 0.06, respectively] but low affinity for rodent NK1 receptors [Ki (nM) 64 and 17, respectively] suggesting that ferret receptors have hNK1-like binding pharmacology. Studies in vivo showed that L-741,671 and L-743,310 had equivalent functional activity in the periphery (ID50s of 1.6 and 2 micrograms/kg i.v., respectively) as measured by inhibition of plasma protein extravasation evoked in the oesophagus of guinea pigs by resiniferatoxin (7 nmol/kg i.v.). Using an in situ brain perfusion technique in anaesthetised rats, L-741,671 was shown to be much more brain penetrant than the quaternary compound L-743,310 which had an entry rate similar to the poorly brain penetrant plasma marker inulin. These compounds thus provided an opportunity to compare the anti-emetic effects of equi-active hNK1 receptor antagonists with and without brain penetration to central NK1 receptor sites. When tested against cisplatin-induced emesis in ferrets, L-741,671 (0.3, 1 and 3 mg/kg i.v.) produced marked dose-dependent inhibition of retching and vomiting but L-743,310 was inactive at 3 and 10 micrograms/kg i.v. In contrast, direct central injection of L-741,671 and L-743,310 (30 micrograms) into the vicinity of the nucleus tractus solitarius or L-743,310 (200 micrograms) intracisternally was shown to inhibit retching and vomiting induced by i.v. cisplatin. L-741,671 and L-743,310 had equivalent functional activity, at the same dose, against cisplatin-induced emesis when injected centrally. These observations indicated that had L-743,310 penetrated into the brain after systemic administration it would have been active in the cisplatin-induced emesis assay and so show that brain penetration is essential for the anti-emetic action of systemically administered NK1 receptor antagonists.

Animals↗
PubMed2003

Visual field defects in albino ferrets (Mustela putorius furo).

The extent of the horizontal visual field was determined behaviourally in 4 pigmented and 5 albino ferrets (Mustela putorius furo, Carnivora, Mammalia) using perimetry. During binocular vision, all pigmented and three albino ferrets responded equally well to stimuli presented anywhere along the horizontal perimeter in the central 180 degrees of the visual field. The remaining two albinos had a visual field defect in the right hemifield (>30 degrees eccentricity). During monocular vision, a significant difference between the visual fields of pigmented and albino ferrets became apparent. In pigmented ferrets, the visual field of each eye included the ipsilateral (temporal) and a substantial portion of the contralateral (nasal) hemifield. In albinos, the visual field of each eye was limited to the ipsilateral hemifield and reactions to visual stimuli abruptly declined directly beyond the vertical meridian.

Albinism, Ocular↗
PubMed1993

Healing of induced periapical lesions in ferret canines.

A previous study showed that the ferret canine is an appropriate model for inducing periapical lesions. Ferret canines were used in this study to study changes in periapical lesions after root canal treatment (RCT). After periapical pathosis was induced in the maxillary and mandibular canines of six ferrets, RCT was performed on three of the four canines in each animal. Each ferret received periodic intraperitoneal injections of Procion red dye. Two animals were killed at each of 4, 8, and 12 wk after RCT. Apices and surrounding lesions were evaluated radiographically, histologically, and by fluorescent microscopy. Periapical radiolucencies increased in size during induction but showed no changes after RCT. Lesions in untreated teeth showed features of granulomatous inflammation, mainly the presence of macrophages and lymphocytes. After RCT, there was histological evidence of healing in the form of cementum deposition, increased vascularity, and increased fibroblastic and osteoblastic activity. Fluorescent staining showed cementum deposition of variable thickness in the treated specimens.

Animals↗
PubMed1984

Altered auditory brainstem evoked responses in the ferret model for Reye's syndrome.

The effects of influenza B, aspirin and hyperammonemia on the functional integrity of the cochlea were examined using the ferret model for Reye's syndrome. Auditory brainstem evoked responses (ABR) were recorded from treated ferrets and compared to those recorded from controls. Delayed latencies of all waves, as well as increased I-IV Interwave latencies were observed in recordings from treated ferrets. Importantly, the latencies of Wave I, nerve generator potential from the eighth nerve, and Wave IV, response potential from the brainstem nuclei, increased on Days 3 and 5 of the study. However, recorded ABR from treated ferrets on Day 10 showed that while the latencies of Wave IV were approximate to those of controls, Wave I remained delayed. These results suggest that systemic effects of influenza B, aspirin and hyperammonemia may lead acutely to both peripheral and central auditory dysfunction, and that the functional integrity of the central auditory system may recover more quickly than that of the peripheral system. Furthermore, these results suggest that such effects may lead to acute transient hearing impairment in patients with Reye's syndrome.

Ammonia↗
PubMed1987

Biology and medicine of the ferret.

There is still much more to be learned about ferret behavior, nutrition, and physiologic responses associated with aging, disease, and environmental stimuli. The many similarities in the clinical disorders of ferrets and other small companion animals should emphasize the importance of using the same diagnostic methods developed for common companion animals in examinations of ferrets. There is still very little known of the efficacy of a wide spectrum of drugs in ferrets, and judicious use of pharmacodynamic agents that are safe for cats would be a reasonable approach to drug therapy.

Animal Diseases↗
PubMed1999

Mucosal vaccination with recombinant poxvirus vaccines protects ferrets against symptomatic CDV infection.

Canine distemper virus (CDV) infection of ferrets causes a disease characterized by fever, erythema, conjunctivitis and leukocytopenia, similar clinically to measles except for the fatal neurologic sequelae of CDV. We vaccinated juvenile ferrets twice at 4-week intervals by the intranasal or intraduodenal route with attenuated vaccinia (NYVAC) or canarypox virus (ALVAC) constructs containing the CDV hemagglutinin and fusion genes. Controls were vaccinated with the same vectors expressing rabies glycoprotein. Animals were challenged intranasally 4 weeks after the second vaccination with virulent CDV. Body weights, white blood cell (WBC) counts and temperatures were monitored and ferrets were observed daily for clinical signs of infection. WBCs were assayed for the presence of viral RNA by RT-PCR. Intranasally vaccinated animals survived challenge with no virologic or clinical evidence of infection. Vaccination by the intraduodenal route did not provide complete protection. All control animals developed typical distemper. Ferrets can be effectively protected against distemper by mucosal vaccination with poxvirus vaccines.

Animals↗
PubMed1999

Intracellular survival of virulent Mycobacterium bovis and M. bovis BCG in ferret macrophages.

The intracellular survival of virulent Mycobacterium bovis and avirulent M. bovis BCG in ferret alveolar macrophages was investigated. In addition, the effects of endogenous and exogenous modulators of macrophage oxidative function on bacterial survival and growth in vitro were determined. Ferret macrophages limited the initial growth of BCG, while virulent M. bovis replicated within macrophages. Intracellular bacterial survival was unaffected by the addition of specific inhibitors of macrophage oxidative function. A T-cell supernatant (TCS), derived from mitogen-stimulated lymphocyte cultures, activated ferret macrophages for heightened oxidative burst performance. However, macrophages activated by TCS, bacterial LPS or a combination of both, failed to control infection, and actually enhanced the intracellular survival of M. bovis. These results are discussed in relation to the role of macrophages in mediating tuberculosis-related pathogenesis, with respect to the fact that ferrets are important wildlife vectors of bovine tuberculosis in New Zealand.

Animals↗
PubMed2002

Ferret orthopedics.

Orthopedic conditions requiring surgical intervention and correction frequently occur in the ferret patient. Elbow luxations and long bone fractures are among the most common syndromes affecting the ferret patient, which often presents in an emergency setting. Orthopedic conditions in the ferret, as in other mammalian species, are often the result of trauma. Surgical treatment including reduction and stabilization of the affected bony structure, combined with supervision and the recommended postoperative care, can provide a good prognosis to return to normal function for the ferret.

Animals↗
PubMed2000

Vagal ganglionic and nonadrenergic noncholinergic neurotransmission to the ferret lower oesophageal sphincter.

In the present study we aimed to discretely characterise ganglionic and neuroeffector transmission to the ferret lower oesophageal sphincter (LOS) using a novel preparation of LOS muscle with intact vagal innervation in conjunction with isolated LOS muscle strips. In this way we could compare vagally mediated LOS relaxation with that of enteric inhibitory motorneurones which were directly stimulated. Preparations of LOS muscle, with or without attached vagus nerves, were dissected from adult ferrets and maintained under preload in organ baths, where LOS muscle developed spontaneous tone. LOS relaxations in response to vagal stimulation (0.5-5 Hz, 30 V) were recorded, alone and following pretreatment with tetrodotoxin (TTX), hexamethonium (Hex), Hex and atropine and NG-nitro-L-arginine (L-NNA). Direct activation of enteric inhibitory motorneurones was performed via electrical field stimulation (EFS). Vagal stimulation elicited frequency-dependent relaxations of the LOS that were abolished by tetrodotoxin (1 microM) and markedly reduced following L-NNA pretreatment (100 microM), but unaltered following pretreatment with the selective VIP or PACAP receptor antagonists VIP (10-28) or PACAP (6-38), respectively (each at 5 microM). The potent NOS inhibitor S-methyl-L-thiocitrulline (100 microM) inhibited LOS relaxation to the same degree at 5 Hz. Hex alone (500 microM) reduced maximal relaxation by 50%; in combination with atropine (2 microM), relaxation was almost abolished. In isolated LOS muscle strips, neither VIP (10-28) nor PACAP (6-38) altered EFS-induced relaxation. Taken together, these results suggest ganglionic neurotransmission to the ferret LOS occurs mainly through a combination of nicotinic and muscarinic receptors and utilises nitroxidergic enteric inhibitory motorneurones to relax the LOS. Moreover, LOS relaxation due to direct activation of inhibitory motorneurones also utilises primarily nitric oxide and other as yet undefined neurotransmitters. Neither VIP nor PACAP are involved in vagally mediated or direct enteric neuronally stimulated LOS relaxation in the ferret.

Acetylcholine↗
PubMed1982

Experimental Trichinella spiralis infection in the ferret, Mustela putorius furo.

Laboratory ferrets (Mustela putorius furo) were each inoculated with 500 larvae of a strain of Trichinella spiralis that had been passaged in mice for many generations. The recovery of adult worms from ferrets on Days 4 and 7 of infection represented a mean of 32% of the inoculum, with most of the worms being in the anterior three quarters of the small intestine. Larvae subsequently became encysted in the ferret musculature, with the diaphragm alone yielding as many as 5,750 larvae upon digestion. For comparative purposes, mice were each inoculated with 200 T. spiralis from the same batch of larvae. The recovery of adult worms from mice represented a mean of 54% of the inoculum. An abrupt decline in worm population, typical of infections in the mouse, was observed in both mouse and ferret hosts; in neither species had the decline begun on Day 7 of infection, but it had clearly begun by Day 11 and was essentially ended by Day 14.

Animals↗
PubMed1988

The characterization and pathological significance of gastric Campylobacter-like organisms in the ferret: a model for chronic gastritis?

Gastric campylobacter-like organisms (CLO) were isolated from gastric tissues removed at sacrifice from 17 mature ferrets; all animals were colonized, but no macroscopic mucosal lesions or histological features of chronic gastritis were seen. The isolates resembled Campylobacter pylori in many cultural and biochemical characteristics, and produced substantial urease activity, but there were sufficient differences from C. pylori to suggest that ferret gastric CLO represents a separate species. Comparison of human C. pylori and ferret gastric CLO may help to elucidate the pathogenicity of the former in patients with gastritis, and the ferret may serve as a useful animal model for the study of C. pylori infection.

Animals↗
PubMedDate not supplied

Prenatal development of axon outgrowth and connectivity in the ferret visual system.

The objective of this study was to determine when the retina, lateral geniculate nucleus (LGN), and striate cortex first send out axons, and first connect with each other, during embryonic development in the ferret. Specifically, we were interested in the timing relationship between axon outgrowth and known temporal patterns of neurogenesis in the LGN and striate cortex. Ferrets (Mustela putorius furo) were selected for study because of their immature developmental state in late gestation and relatively large litters. We examined axon outgrowth from the retina, and anlagen of presumptive LGN and striate cortex between embryonic day 21-30 (E21-E30) using in situ inoculations of two fluorescent lipophilic dyes, DiI and DiA. DiI inoculations were made into the cortex and contralateral thalamus, and DiA inoculations were made into the contralateral eye. Retinal axon termination zones in the diencephalon following the DiA inoculations were used to validate the location of the LGN. Visual cortex and LGN neurogenesis begins at E20 in ferrets. No axon outgrowth could be documented from retina or anlagen of striate cortex and LGN until E24. At E24 some retinal axons reach and cross the chiasm, cortical axons extend some distance within the cortical radiations, and thalamic axons are within the internal capsule. Retinogeniculate, geniculocortical, and corticogeniculate axons extend to their target structures by E27, as evidenced by retrograde labeling in cells of origin. These data suggest that in the ferret retina, and developing LGN and striate cortex, (1) axon outgrowth from each visual area begins within 24-h of each other, after neurogenesis has begun at the source but before it is complete in the target; (2) axons may be generated before parent cell bodies have completed migration; and (3) arriving axons are in a position to influence target structures almost from their inception.

Animals↗
PubMed1992

Visual callosal projections in the adult ferret.

The laminar and tangential organization of visual callosal projections of areas 17 and 18 were investigated in the adult ferret, using histochemical methods to visualize axonally transported horseradish peroxidase (HRP). Normal adult ferrets were given injections of HRP throughout one visual cortex or had gelfoam soaked in HRP applied to the transected corpus callosum. The ferret callosal cell distribution has a greater tangential extent in area 18 than in area 17. In addition, the radial organization of callosal cells in areas 17 and 18 differs: three times as many infragranular cells are present in area 18 than in area 17, although the number of supragranular cells is similar for both areas 17 and 18. Since the projections of alpha retinal ganglion cells are reported to be exclusively contralateral in the ferret (Vitek et al., 1985), callosal projections may make a major contribution to the binocularity of neurons in area 18.

Animals↗
PubMed1991

Albino gene dosage and retinal decussation patterns in the pigmented ferret.

We have examined the retinal decussation patterns in pigmented ferrets that were either wild-type sable or heterozygous with one albino gene. Unilateral injections of horseradish peroxidase were made into the optic tract and labeled ganglion cells visualized in retinal wholemounts. In both wild-type and heterozygous ferrets, those ganglion cells in the temporal retina with the largest cell bodies projected only to the contralateral side of the brain. The total number of ipsilaterally projecting ganglion cells did not differ with the genotype of the animal. The numbers ranged from 5471-6759 cells. Unlike the cat, there is no difference in retinal decussation patterns in wild-type sable ferrets and heterozygous ferrets carrying one albino gene.

Albinism↗
PubMedDate not supplied

Overrepresentation of the central visual field in the superior colliculus of the pigmented and albino ferret.

We have examined the retinotopy in the superior colliculus of pigmented and albino ferrets using both anatomical and electrophysiological methods. While the distribution of contralaterally projecting retinotectal ganglion cells is characterized by the presence of an area centralis superimposed on a visual streak in both strains, the ipsilateral projection from temporal hemiretina is strongly reduced in albinos. In spite of the significantly altered retinotectal projection pattern, the collicular visual field map in the albino ferret reveals the same characteristics as in the pigmented animal with a strongly enlarged representation of the center of visual space. An areal comparison between retinotectal ganglion cell distribution and collicular areal magnification shows that the increase in areal magnification factor between the periphery and the representation of the central visual hemifield exceeds the corresponding increase in retinal ganglion cell density between peripheral retina and area centralis by a factor of three in pigmented and a factor of four in albino ferrets. The areal magnification factor of the representation of the retinal visual streak does not exceed the increase in retinotectal ganglion cell density. Thus, our results suggest that the representation of visual space in the superior colliculus of albino and pigmented ferrets does not simply follow the retinotectal ganglion cell density, but that there is an enhanced representation of the frontal central visual field. The possibility is discussed that the collicular visual field map may be determined either by both retinotectal and corticotectal projections or by the colliculus' intrinsic structure.

Albinism, Ocular↗