ANIMAL CAGE

Abstract: An animal cage for use with animals involved in research and having a back panel (20) movable between a rear, free animal, station and a forward, restrained animal, station. The movement is obtained via a reversible ratchet device (30) carried on a rotatable ratchet bar (31) extending centrally through the cage from front to rear. The bar (31) has a series of notches (31a) therealong engageable by the ratchet device (30). With the bar (31) in one of two rotation stations the bar may be pumped to bring the back panel (20) to the forward station, while in the other rotation station the back panel may be returned to the rear station.

Description: ANIMAL CAGE This invention relates to animal cages and in particular to animal cages for animals employed in research. Cages for animals employed in research advantageously incoφorate means for confining the animal in a small, typically frontal, area of the cage while treatment or measurements are being carried out. In this way the treatment or measurement can be effected in a manner which is safe for both animal and researcher. Such cages are known. For example US Patent No. 3,791,347 describes a small animal carrier comprising a movable floor panel operated manually by means of a push/pull knob. US Patent No. 5,251 ,572 describes a cage comprising a pivotal floor and back panel which operates to restrain the animal between the raised floor and the front panel of the cage. One disadvantage of both these systems is that the restraining- means is operated from a position remote from the door of the cage so that the operator is unavailable to assist with handling or treating the animal. US Patent No. 3,399,654 describes a large cage wherein a sliding wall is operated by means of a chain and sprocket mechanism in order to confine the animal in a much reduced space near the door of the cage. This system has the advantage that the restraining means is operable from a position adjacent the front of the cage allowing the operator to observe and handle the animal without assistance. However it is a further important requirement of an animal cage that, if as is usual it is to be reusable, it be capable of sterilization, since the animals may carry infectious diseases. Typically, large animal cages are cleaned in a cage washer in which the cage is hosed at high pressure with water at about 80°C and acids and chemical disinfectant detergents, then autoclaved at a high temperature, typically over 130°. The process of disinfection is facilitated the simpler is the structure and the less there are traps within which animal soil and detritus may gather. Moreover it is disadvantageous to the cost of ownership and minimization of out-of-service time of a cage such as that described in US Patent 3,399,654, if there are moving parts the lubricants of which will be removed by the disinfecting process, requiring renewal before the cage is used. If an oiled chain is used then it can be necessary to shield it from contact by the animal and attraction of animal soil, but then to have access to it for lubrication. It is an object of the present invention to provide an animal cage incorporating animal restraining means which mitigates the above mentioned problems. According to the present invention there is provided an animal cage comprising a back panel mounted to be movable between a rearward position and a forward position wherein a reversible ratchet mechanism comprises a rotatable ratchet bar extending between the back of the cage and the front of the cage and two opposed ratchet engaging means associated with the back panel, the first engaging means being adapted to engage the ratchet bar when it is rotated into a first position and the second engaging means being adapted to engage the ratchet bar when it is rotated into a second position such that application of a longitudinal pumping movement to the ratchet bar reversibly drives the back panel between its rearward and forward positions. An advantage of this type of reversible ratchet mechanism is that it comprises a minimum number of mechanical parts, and can readily be constructed to require no lubrication and a minimum of maintenance. Ideally a single bar is employed, approximately centrally located in the cage. For the puφoses of the mutual protection of the bar and the occupying animal one from the other, the cage may incorporate a platform for use by the animal, extending from front to rear of the cage just above the bar. Advantageously this platform can be arranged to be at least partly constituted by rail means which both support the back panel and, via rollers, assist in guiding it between the forward and rearward positions. A cage suitable for rhesus monkeys may be of the order of 2 metres tall by 1.2 to 1.5 metres square base, and a suitably stiffened back panel may be fully supported by the bar and two rails of a central platform. The cage may be constructed of lightweight stainless steel tube, both of round and rectangular section, and of stainless steel rod mesh, welded together. In this way its integrity and strength, durability, and sterilisabiiity are maximized. So too is its simplicity, for this type of construction means that hinged or sliding doors and hatches can readily be incoφorated via judicious welding. The rollers, if they are made of brass or have brass bearings, will withstand the disinfecting process without requiring additional maintenance. A cage on castors can readily be arranged to accommodate removable underfloor trays, but is also preferably provided with anchoring means. Conveniently these may be realized in lugs arranged for attachment to the wall of a laboratory or other building. Such anchoring means also facilitate the creation of an interlinked pair or even group of cages. If accordingly cages have access hatches in the sides, for example adjacent the top front corner where they require the inmate to climb to for use, cage link means can be attached between the hatches of adjacent cages. The link means may have trays which, like the underfloor trays, can be arranged to contain bits of food mingled with sawdust and wood-shavings etc. This enables the animal to indulge in a natural foraging activity and thus provides that environment enrichment which is essential for its psychological and physiological well-being. The castors are also preferably provided with tyres and bearings which withstand the disinfecting process and do not require maintenance after each cleaning. The ratchet bar preferably extends through the front panel of the cage to provide a handle for operation and to allow the restraining means to be operated whilst the door of the cage is closed. For certain operations such as observation and administration it may be sufficient that the animal is held against the front wall by the advanced back panel and the cage door not opened. In situations where it is necessary to open the door and catch the animal the risk of injury to the handler and the animal is reduced by virtue of this restraint. Typically the ratchet bar has a series of recesses arranged equispaced along the length of the ratchet bar. The smaller the pitch of the recesses, and the greater their number, the lower is the amplitude of the required pumping action. With a pitch of 4" to 8" the bar may be operated at a distance from the front of the cage which is safe from attack by the animal yet permits contemporary ministration to the animal by the operator if required. The ratchet engaging means are conveniently leaf springs, made perhaps of stainless steel. They may be mounted in a block assembly secured to the back panel and movably mounted on the ratchet bar. The ratchet bar assembly may incoφorate locking means for locking the bar with the back panel in its rearmost configuration. The invention will now be described, by way of example only, with reference to the accompanying drawings, in which:- Figure 1 is a front and side part cut away perspective view of an animal cage according to the present invention; Figure 2 is a part cut-away view of the ratchet bar and block assembly according to the invention; Figure 3 is a part cut-away view of the ratchet bar and block assembly of Figure 2 showing the ratchet mechanism in reverse mode; and Figure 4 illustrates a link cage associated with the animal cage. The figures illustrate a cage suitable for holding rhesus monkeys employed in laboratories. The cage is rectangular, with front, side, floor and roof members. The front comprises two doors hinged at the cage sides and lockable onto a central pillar. The front is constructed of round stainless steel tube bars 10 penetrating square section stainless steel tube ribs 11 and edge members 12, to which the bars 10 are welded where appropriate - at the top and bottom of each door there are hatches 13 and 14 which slide open. In the case of the lower hatches 14 the tubes thereof slide within those of the door, whilst in the case of the top hatches 13 the tubes thereof slide up through holes in the door frame. The sides, floor and roof are formed by stainless steel rod mesh (15) attached to square section stainless steel edge and rib members. At the rear of the cage the sides are linked by a cross member 16 approximately centrally. Between a central front rib and the cross member 16 extend a plurality of stainless steel tubes in flat array forming a platform 17 occupying the centre third of the cross section of the cage. The outermost tubes 17a are more substantial than the other tubes 17b and constitute rail members. A back panel 20 is a snug but free fit within the sides, floor and roof of the cage. It is constituted by a stainless steel sheet stiffened by attachment to a frame of square section stainless steel tube. It is freely penetrated by the tubes 17a and 17b and supported within the cage by rollers 21 which engage on the tubes 17a. The rollers are made of brass in order to be self-lubricating. A back panel driving device 30 is mounted in the cage immediately below the platform 17. It comprises a ratchet bar 31 and a ratchet engaging block 32. The ratchet bar 31 has a series of drive notches 31a formed along a particular line thereon, a control handle 33 and a locking bar 34 at a forward end thereof and a locking bush 35 at a rear end thereof. The ratchet engaging block 32 incorporates a pair of stainless steel leaf springs 32a and 32b. The ratchet bar 31 extends from front to rear of the cage, passing through the block 32 so that the bush 35 is behind the back panel 20. The leaf springs 32a and 32b impinge upon the bar at diametrically opposed locations, with one leaf spring 32a facing forwards and the other (32b) facing rearwards. The pitch of the notches 31a is 6". At the top front corner of the side walls are sliding hatches 18. Link members 40 are attachable to the sides of the cage, as shewn in Figure 4, whereby an interconnection may be formed with another like cage. The link member 40 has an associated detachable tray 41. The floor of the cage is so mounted upon castors 50 that trays 51, coterminous with the floor, are emplaceable beneath the cage upon their own castors 52. Preferably there are two trays 51 per cage. Anchor probes 53 project rearwards from the rear side frame, whereby the cage may be anchored to the wall of a room. Locking means are provided for the locking of all doors and hatches, for locking the locking bar 34 to the front of the cage and for locking the link members to the cages. In use of the cage the primate may be installed via any one of the doors and these may be used for handler and researcher access in appropriate circumstances. The primate will forage through the floor of the cage for additional food which has been placed in the trays 51 in sawdust or the like. Water is delivered via a bottle attached to the cage wall in a conventional manner. When it is necessary to administer a drug under trial, for example, to the animal the back panel 20 can be drawn forward by the researcher grasping the handle 33 and, with the ratchet bar 31 in the forward motion configuration, pumping it backwards and forwards so that the leaf spring 32a engages the notches 31a successively. When the animal is impinged by the back panel 20 against the cage front wall the administration can be effected. When this is complete the researcher can rotate the ratchet bar 31 using either the handle 33 or the locking bar 34, to align the notches 31a with the leaf spring 32b. Pumping action on the ratchet bar 31 then drives the back panel 20 to its rearward position. The cage will normally be anchored to the wall of the laboratory, and in various circumstances can be linked to one or more other cages via the link members 40, to increase the space and intricacy of the accommodation and to permit living in community. It is advantageous to the animals' welfare for them to have to forage for their food and cages in accordance with the invention permit food to be either pushed through the walls or placed upon the roof. The feature of having trays 51 permits regular changing of the sawdust and addition of food. It also permits the trays to be cleaned more frequently than the cage per se if desired. The trays and the cage may be cleaned by pressure jets of suitable cleaning and disinfecting fluids and by autoclaving. The construction of the invention assures that such cleaning may be effected thoroughly with maximum economy of time and materials and without deleterious effect upon the cage.

Claims: CLAIMS 1. An animal cage having a back panel mounted to be movable between a rearward position and a forward position and a reversible ratchet mechanism comprising a rotatable ratchet bar extending between the back of the cage and the front of the cage and two opposed ratchet engaging means associated with the back panel, the first engaging means being adapted to engage the ratchet bar when it is rotated into a first position and the second engaging means being adapted to engage the ratchet bar when it is rotated into a second position such that application of a longitudinal pumping movement to the ratchet bar reversibly drives the back panel between its rearward and forward positions. 2. A cage as claimed in claim 1 and wherein the ratchet bar is located approximately centrally of the cage. 3. A cage as claimed in claim 1 or claim 2 and having a platform immediately above the ratchet bar. 4. A cage as claimed in claim 3 and wherein the platform includes runner members upon which the back panel is supported and runs. 5. A cage as claimed in any one of the preceding claims and constructed of stainless steel tube and stainless steel rod mesh. 6. A cage as claimed in any one of the preceding claims and having a mesh floor beneath which are sitable mobile trays. 7. A cage as claimed in claim 6 and having associated mobile trays. 8. A cage as claimed in any one of the preceding claims and having wall anchoring means. 9. A cage as claimed in any one of the preceding claims and having a hatch to which cage link means can be attached. 10. A cage as claimed in claim 9 and having detachable link means. 11. A cage substantially as hereinbefore described and with reference to the accompanying drawings.

Inventors: SHORT BARRY DAVID, SMITH JEREMY NICHOLAS, VEALL DAVID JAMES, SHORT, BARRY, DAVID, SMITH, JEREMY, NICHOLAS, VEALL, DAVID, JAMES
Applicants: SECR DEFENCE, SHORT BARRY DAVID, SMITH JEREMY NICHOLAS, VEALL DAVID JAMES, SHORT, BARRY, DAVID, SMITH, JEREMY, NICHOLAS, THE SECRETARY OF STATE FOR DEFENCE, VEALL, DAVID, JAMES
Application year: 1997
Main classification: A01K1
IPC codes: A01K1