Abstract:
An animal cage includes a removable, suspended interior floor provided with a plurality of perforations formed therein. The floor creates a plenum inside the cage allowing air to flow laminarly through the perforations and liquids or liquid waste to substantially fall through the perforations in the raised floor.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The present invention relates to caging systems for laboratory animal care and more particularly to a cage and system which has controlled ventilation, waste containment and cage construction that will direct airflow through the bedding, thus keeping it dry which will reduce bacteria formation caused by humidity and moisture. 
         [0002]    Most all existing ventilated rodent cage systems are made with plastic clear solid-bottom cages. Clear cages are used so it is possible to inspect the condition of the inside of the cage without disturbing the animals. The solid bottom of the cage compartment is used to hold bedding material. The cage ensemble generally consists of a metal wire bar lid containing a feed hopper and water bottle capabilities and a plastic top that holds a piece of filter media. The cages are contained in a rack that holds a plurality of cages either single or double sided. An automatic water system introduces water into the cage for the rodent using lixits or water valves located either outside or inside the cage. It must be monitored for proper water pressure and must be flushed periodically. Problems of leakage, high intracage humidity levels and cage flooding are associated with automatic watering systems. Airflow is introduced into the cage either positive or negative pressure in an attempt to rid the cage of harmful contaminants, mainly ammonia and CO2. A plenum, either a separate duct system or made up of components of the rack (i.e. the shelves or the tubing uprights), supply the cage with filtered air through a cage mounted or detached air supply diffuser. Air flow in present designs is either transversely across the cage from the front or rear wall, or, from an inlet in the top of the cage to an outlet in the junction of the top of the cage. 
         [0003]    The applicant is aware of the following U.S. patents which are related to cages for laboratory animals: 
         [0004]    Fricke U.S. Pat. No. 2,467,525; Fuller et al U.S. Pat. No. 3,063,413; Barney U.S. Pat. No. 3,397,676; Holinan U.S. Pat. No. 3,924,571; Gland et al U.S. Pat. No. 4,085,705; Gass U.S. Pat. No. 4,154,196; Nace 4,201,153; Thomas U.S. Pat. No. 4,402,280; Picard et al U.S. Pat. No. 4,435,194; Sedlacek U.S. Pat. No. 4,480,587; LoMaglio 4,526,133; Spengler 4,528,941; Peters et al 4,798,171; Niki 4,844,018; Spina U.S. Pat. No. 4,869,206; Niki et al U.S. Pat. No. 4,940,017; Sheaffer U.S. Pat. No. 4,989,545; Niki et al U.S. Pat. No. 5,003,022; Niki et al U.S. Pat. No. 5,048,453; Coiro, Sr. et al; U.S. Pat. No. 5,148,766; Coiro, Sr. et al U.S. Pat. No. 5,307,757; Sheaffer et al U.S. Pat. No. 5,311,836; Harr U.S. Pat. No. Re 32,113; Semenuk D U.S. Pat. No. 351,259; Semenuk D U.S. Pat. No. 383,253 
         [0005]    Current ventilated caging systems, of which the applicant is aware, for laboratory animal care and use in biomedical research/testing is suboptimal because of the lack of the ability to actually dry the bedding which is the root cause of ammonia gas formation. Present units require 60 or more air changes per hour and have been shown to be ineffective in removing all traces of contaminants. Even small concentrations of ammonia have been shown to cause lesions in the respiratory tracts of mice. In addition, mice are borrowing animals and this behavior leads to prolonged periods with their nasal passages in or very near the bedding which is where the harmful ammonia vapor is forming, and they are burrowing in bedding that can be moisture laden from urination and a leaking water source. Bedding has been deemed as a necessary enrichment for rodents. Present day systems do not address the moisture removal from bedding. Their only attempt to dry the bedding is reduce the cage humidity level by high air change rates in the cage. Due to the high intra-cage ventilation rates required with existing ventilated racks, animal losses can occur due to chilling and dehydration of neonates, hairless and nude strains. While the systems currently in use may provide some biological exclusion, the inability to dry the bedding material, contributes to a lack of animal comfort, and requires an enormous amount of conditioned laboratory air every hour. Filtering air through the bedding attacks the source of ammonia formation whereas other systems only treat the symptoms. By attacking the contamination source, lower amounts of air are required to ventilate the cage effectively. This results in reduced HVAC costs and lower mechanical, electrical and plumbing costs during renovations or new construction due to the smaller system requirements. 
         [0006]    In present systems, bedding and nesting materials are placed directly on the floor of the solid-bottom cages, since rodents are nesting and burrowing animals. The primary requirements of bedding materials are: (1) the material must not be harmful to the animal; (2) it must be capable of absorbing moisture without causing dehydration of newborn animals, (3) it must not create excessive dust, (4) it must be economical to use and dispose of. Modern bedding materials are absorbent, but, the fact that the bedding is absorbing moisture allows the formation of urease bacteria which then produces ammonia. A major goal is to direct airflow in the cage in such a manner that it keeps the bedding dry, eliminating the formation of the urease bacteria, thus, creating a better cage environment. Since the harmful contaminants are kept from forming, airflow requirements can be reduced, drastically reducing energy requirements in the lab. Reduced airflow in the cage will also reduce aerosols from bedding dust which reduces the clogging of the cage outlet filter. When cages are operated in a negative pressure for bio-containment purposes, the clogging of the outlet filter could cause the cage to revert to a positive pressure environment which could release cage air into the room. Dry bedding is more easily removed from the cage during change-out periods than wet bedding which can adhere to the cage, making removal difficult and time consuming. Reduced airflow results in lower intra-cage sound levels which could result in less stress on the animal and encourage a more optimum breeding environment. Thus, there is a need for a laboratory animal cage and a system of cages which solve these problems. 
       BRIEF SUMMARY OF THE INVENTION 
       [0007]    It is an object of the invention to provide a cage for laboratory animal care which has a laminar air flow from bottom to top to permit a healthy environment. 
         [0008]    It is still another object of the present invention to provide a cage for laboratory animal care which can exhaust excess water automatically preventing cage flooding. 
         [0009]    It is yet another object of the present invention to provide a system of cages in a rack in which the air flow through each individual cage is controlled, adjustable by the user and there is no cross contamination between the cages. 
         [0010]    It is still a further object of the present invention to provide a cage for laboratory animal care to permit optimal animal housing flexibility, protect animal and occupational health by providing a barrier at cage level for exclusion, containment or both, validate data reproducibility; and provide for optimal animal comfort and well-being. It will provide a natural environment promote rapid waste desiccation, eliminate waste contaminant&#39;s harmful by-products, save husbandry-related costs, and convey a positive image to the public. 
         [0011]    In accordance with the teaching of the present invention there is disclosed an animal cage for laboratory purposes. The cage has a solid floor bottom with a means to suspend a panel, provided with a plurality of perforations formed therein, the perforations to be small enough to allow air to pass through but not allow bedding to fall through above the solid cage floor 
         [0012]    In further accordance with the teachings of the present invention, there is disclosed a cage for laboratory animal care. The cage has a body having four walls and a solid floor with another removable perforated floor suspended above the cage floor which defines the living space for the animal. A lid is removably connected to the body. There is provided means for circulating clean air through the cage. The cage is air tight. In at least some embodiments, the cage is air permeable. 
         [0013]    Also, there is disclosed a cage for laboratory animal care. The cage has a body having four walls and a solid floor with another removable perforated floor suspended above the cage floor which defines the living space for the animal. A lid is removably connected to the body. An air outlet port is formed in the lid. An air inlet port is formed in one of the walls of the body beneath the suspended floor. Means are provided to circulate air between the air inlet port and the air outlet port. 
         [0014]    Additionally, there is disclosed a cage for laboratory animal care. The cage has a body having four walls and a solid floor with another removable perforated floor suspended above the cage floor which defines the living space for the animal. A cage wall has an air inlet port formed between the cage floor and the suspended floor. A lid is removably connected to the body, the lid having an air outlet port formed therein. A clean air supply is connected to the air inlet port wherein the clean air flows through the air inlet port, into the space between the cage floor and suspended floor, the clean air flowing laminarly upwardly through the living space for the animal, through the perforated bedded floor, and out the air outlet port. The air flow removes from the cage, particulate matter, allergens and gases associated with waste products. 
         [0015]    In another aspect, there is disclosed a ventilated cage system for laboratory animal care having at least one cage having a body. The body has a top and a removable suspended perforated floor. A separate lid is connected to the top, an air outlet port being formed in the lid, wherein each cage is air tight. An air inlet port is formed in the wall of the cage body below the suspended floor with bedding. A rack is provided for supporting at least one cage. An air supply introduces air into the air inlet port in the body. The air flows laminarly from the removable perforated suspended floor with bedding of each cage, through each cage, and through the air outlet port of each lid. In this manner, fresh air is maintained in at least one cage and waste air is removed from at least one cage. 
         [0016]    In still another aspect there is disclosed a cage system for laboratory animal care including at least one cage having a body having a top, four side walls and a removable perforated suspended floor. A lid is removably connected to the top of the body. A rack and means for supporting the at least one cage on the rack is provided. 
         [0017]    These and other objects of the present invention will become apparent from a reading of the following specification taken in conjunction with the enclosed drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0018]      FIG. 1  is a front elevation view of a rack in which are mounted a plurality of cages for laboratory animal care of the present invention. 
           [0019]      FIG. 2  is a side elevation view of two cages mounted vertically and connected to the air supply and exhaust system. 
           [0020]      FIG. 3  is a schematic diagram of the ventilated cage system of the present invention. 
           [0021]      FIG. 4  is a perspective view of the cage. 
           [0022]      FIG. 5  is an exploded view of the cage. 
           [0023]      FIG. 6  is a partial cross section view of the cage showing the sealant means. 
           [0024]      FIG. 7  is a top plan view of a portion of the removable suspended perforated floor. 
           [0025]      FIG. 8  is a cross-section view of a portion of the removable suspended perforated floor with bedding, along the lines  8 - 8  of  FIG. 7  showing an animal in the cage. 
           [0026]      FIG. 9  is a perspective exploded view of a cage as viewed from the top. 
           [0027]      FIG. 10  is the embodiment of  FIG. 9  viewed from the bottom. 
           [0028]      FIG. 12  is a perspective view of the cage with a water bottle attached externally. 
           [0029]      FIG. 14  is a partial cross-section end view showing the cage supported on the rack with the lid on. 
           [0030]      FIG. 15  is an end view showing the cage supported from the rack with the lid on. 
           [0031]      FIG. 16  is an end view showing the cage supported on the rack with the lid off. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0032]    Referring now to  FIGS. 1-5 , a plurality of cages  10  are supported on a rack  12 . Preferably, the rack  12  is a frame mounted on wheels with a plurality of cage suspension brackets having one or more cages  10  on each bracket. 
         [0033]    Each cage  10  is individually connected to an air supply  14  which serves all of the cages  10  in the rack  12 . A filter  16  is provided in the air supply. The filter may be a HEPA filter and may also include a prefilter. A blower  20  is disposed in the air supply system to move the air through the cages  10  and the filter  16 . The filtered air enters a manifold  18  which is connected by hoses to the individual cages  10 . The filter system removes particulate matter and pathogens larger than 0.003 microns in size. 
         [0034]    Each cage  10  has a body  22  having four walls and a bottom surface  24  and a removable suspended perforated floor  25  with bedding  19  on top to define a living space for the laboratory animals. A separate lid  26  is removably connected to the top of each body  22 . An air outlet port  28  is formed in each lid  26 . An exhaust prefilter  36  can be inserted between the lid  26  and a filter retainer  37 . The lid rest on a feeder plate  32  which has a plurality of spaced-apart orifices  30  formed therein. Preferably, the orifices are distributed over the entire area of the feeder plate  32 . 
         [0035]    It is preferred that all corners and the intersections of walls and bottom surface of the cage be rounded to reduce the accumulation of dirt and waste and to facilitate cleaning of the cage. It is preferred that the body of the cage be made of high temperature plastic and that the cage be transparent to permit observation of the animal within the cage. 
         [0036]    It is preferred that a feeder plate  32  be disposed between the lid  26  and the body  22  of each cage  10 . The feeder plate  32  may be a frame structure which has an angled portion  34  which extends downwardly into the living space of the animal within the body  22  of the cage. The angled portion  34  may have a “V” shape. The feeder plate may be metal or plastic. The feeder plate  32  supports containers of food, water and/or special liquid supplements  38  for the animal. The perforated feeder plate  32  also optimally acts as an air diffuser creating a plenum when coupled with the lid  26 . 
         [0037]    The body surface (or floor)  24  of the cage  22  is solid. The removable suspended floor  25  is formed having a plurality of spaced-apart perforations  40  ( FIGS. 7 and 8 ). Although not limited to these sizes, it has been found that a satisfactory floor has holes which are approximately 0.055 inches in diameter and suspended approximately ¾ inch in height above the surface of the cage floor. Air, liquids and liquid waste from the animal passes through the perforations  40  into the cage body. 
         [0038]    Preferably, a gasket  48  is fitted between the body  22  of the cage  10  and lid and the body  22  of the cage  10  ( FIG. 6 ). The lid  26  is attached onto the cage  10  and is easily installed and removed by applying pressure on the lid  26  to snap on and off over the gasket  48 . In this manner the lid  26  can be easily replaced with a clean lid saving costly man hours. The gasket  48  may be any sealable closure between the body  22  and the lid  26 . By use of similar sealing techniques known to persons skilled in the art, each cage system is air tight and the air flow within each cage is restricted to the specific cage. There is no leakage of air from any cage into the room in which the cage is housed nor is there any air interchange between any cages. Cage to cage contamination is prevented. 
         [0039]    The cage body  22  has an inlet port  50  formed therein through which the air entering the cage  10 , may flow. Also, water or liquid waste products from the animal may exit from the inlet port  50  or alternately another port  62 . The waste air, after flowing out of the outlet port  28  is directed preferably through a hose, to the exhaust filter  15  and the particulates and toxic gases are removed. Air is then resupplied through the inlet filter  16  to the cage system. An adjustable blower  52  in the air supply system is used to control the rate of air flow as needed depending upon the desired conditions and the strain of animal within the cage. Due to the configuration of the cage system and the perforated feeder plate  32  and raised perforated floor  25  with bedding  19  on top of the individual cage, the air flow through each cage is laminar from the bottom of the cage, through the bedding  19 , to the top of the cage ( FIGS. 2 and 3 ). In this manner, the animal and bedding  19  is continuously provided with fresh air. The air, after passing through the body  22  of the cage  10 , through the raised floor with bedding dries any waste products which may be in bedding  19  or on the floor  24  of the cage  22  and removes or prevents ammonia and other vapors in the system. 
         [0040]    A water valve  54  is fitted into the body  22  of the cage  10  and is connected to a water supply  56 . The water valve  54  may be manually or automatically controlled to supply the animal with water. The removable suspended perforated floor  25  of the cage and the inlet port  50  of the cage body  22  or other outlet port  62  permit the water to drain from the cage and prevent flooding. The excess water flows to a reservoir  58  and to a drain to be removed from the system. 
         [0041]    The cages  10  may be made in a variety of sizes to accommodate laboratory animals of varying sizes. 
         [0042]    The intracage airflow system serves as an effective barrier system by preventing the transmission of contaminated particulates and aerosols from cage-to-cage and rack-to-rack. The system uses airflow to prevent or control airborne infection of laboratory animals. The flow of air sweeps the bedding free of gases, particulate matter, allergens and removes them through the filtered outlet port in the lid, keeping the cage environment cleaner than other filtered air cage designs. The HEPA filter (both supply and exhaust) is connected to a baffling system which reduces turbulence and directs the airflow into a distribution plate. This plate houses the connections for the flexible tubing that act as a plenum and either delivers or exhausts air from each cage. Preferably, each tube is of equal length thus supplying or exhausting each cage the same no matter where it is located on the rack. Each tube is housed in a hollow shelf and preferably terminated at the cage with a stainless steel nipple. The air flow to each individual cage is automatically balanced to provide approximately the same air flow into each cage in the system. This may be accomplished by controlling the lengths of the tubing, baffles, varying duct size and other means known to persons skilled in the art. 
         [0043]      FIGS. 9 and 10  show another embodiment of the cage  10 . The body  22  has four walls and a removable suspended perforated floor  25  with bedding  19  on top, to define the living space for the laboratory animal. A lid  26  is removably connected to the top of the body  22  and. An air outlet  28  is formed in the lid and an air inlet  50  is formed in the body of the cage below the raised suspended floor. Preferably, the surface of the feeder plate  32  has a plurality of spaced-apart orifices  30  formed therein to facilitate laminar flow of the air through the cage  10 . A water valve  54  is formed in one of the walls of the body  22 . The cage  10 , preferably is formed of a transparent plastic. Thus, the embodiment of  FIGS. 9 and 10  is very similar to the embodiment of  FIGS. 4 and 5 . However, the feeder preferably is omitted from the embodiments of  FIGS. 4 and 5 , although it could be included. The lid  26  has handles  60  formed thereon to assist in removing and attaching the lid  26  from the body  22 . Also, the air inlet in the body will function as a water overflow outlet  62  to drain water and liquid waste from the cage body ( FIG. 9 ). It is preferred that the water overflow outlet operate automatically so that there is very little accumulation of liquid in the cage body. 
         [0044]    As previously described, the cage  10  has a source of water  56  connected to the water valve  54  to provide automatic water feed to the laboratory animal. As shown in  FIG. 12 , a water bottle  38  may be connected to the water valve  54  where the water bottle  38  is external to the cage  10 . This arrangement permits the water to be replenished when necessary without opening the cage  10 . Each cage  10  may be disposed in the rack  12  with the respective water valve  54  directed outwardly from the rack  12  such that each externally connected water bottle  38  is readily accessible to an attendant. This construction is especially useful for situations where special diets or additives in the water are provided to the laboratory animals and the water bottles are easily and rapidly accessible. 
         [0045]    The cages  10  of the present invention may be supported in the rack  12  in several ways ( FIGS. 14-16 ). The cage body  22  with the lid  26  attached, is supported by a shelf  68  beneath the cage  10 , without contacting the shelf  66  above the cage  10  ( FIG. 14 ). Alternately, ( FIG. 15 ) the cage body  22  with the lid  26  may be attached to a shelf  66  of the rack using tracks, clips or other means known to persons having ordinary skill in the art. In yet another configuration, the lid  26  is removed and the top of the body  22  may be attached to a shelf  66  of the rack using tracks, clips or other means known to persons having ordinary skill in the art. 
         [0046]    Devices may be secured (snap-on) to the removable suspended perforated floor. These devices are made from appropriate non-toxic material that favors isolation, nest building and thigmotactic behaviors, as well as providing protective or escape mechanisms for submissive animals. The airflow flowing through the bedding prevents the formation of harmful contaminants thus reducing the need for higher airflows in other designs which are addressing the symptoms and not the cause of the formation of contaminants, saving considerable costs on HVAC and larger mechanical systems. Additionally, the elimination of bedding results in considerable cost savings. A central HEPA filtering unit may be mounted on each rack, room mounted to supply several racks or centrally located in a facility to supply many rooms with racks. These systems are all equipped with visual and audible alarms and monitors to alert facility personnel of problems or failures of air flow, temperature, humidity, water leakage, or filters. A battery-operated power supply system can be provided in the event of a power failure. 
         [0047]    In summary, one or more embodiments of the cage system of the present invention provides one or more of the following unique features: 
         [0000]    bedding free cage uses a perforated floor
 
a plenum lid
 
the lid has spaced-apart orifices for air flow
 
an adjustable blower to vary the air supply and exhaust
 
unit can accommodate various animal strains by user adjusted airflow
 
separates air and water from the exhaust (prevents cage flooding)
 
air is supplied into top of cage and removed at bottom. Air flow direction is laminarly downward.
 
air is supplied into the bottom of the cage beneath the suspended perforated floor and removed at the top. Air flow direction is laminarly upward.
 
closed system maintains an approximately neutral pressure in the cage closed system maintains either positive, negative or neutral pressure in the cage
 
airflow is delivered and exhausted via a unique distribution system which automatically balances the airflow in each cage
 
maintains and monitors temperature and humidity at cage level
 
maintains and temperature and humidity at cage level
 
snap-on enrichment devices
 
battery back-up for the HEPA unit
 
monitors and alarms when problems occur
 
centralized air supply at room or facility level
 
sealed cages
 
a water valve connected to a source of water
 
a water bottle external to the cage connected to the water valve
 
water and waste liquid automatically drain from the waste tray
 
liquid and liquid waste automatically drain from the cage body
 
alternate means for supporting the cages in the rack.
 
         [0048]    Obviously, many modifications may be made without departing from the basic spirit of the present invention. Accordingly, it will be appreciated by those skilled in the art that within the scope of the appended claims, the invention may be practiced other than has been specifically described herein. 
       LIST OF PARTS 
       [0000]    
       
           10  Cages 
           12  rack 
           14  air supply 
           16  filter 
           17  Air Exhaust 
           18  Manifold air supply 
           19  Bedding 
           20  Blower air supply 
           22  Cage Body 
           24  Bottom of cage 
           25  Raised floor 
           26  Lid 
           28  Air outlet 
           30  holes in Feeder plate 
           32  Feeder Plate 
           34  Wire bar Feeder/Water bottle holder 
           36  Exhaust Filter 
           37  Exhaust filter Retainer 
           38  Water Bottle 
           40  Holes in Raised Floor 
           48  Gasket for Lid 
           50  Air Inlet Port 
           52  Air Supply Valve 
           54  Water Valve 
           56  Water Supply 
           58  Water Reservoir 
           60  Handles 
           62  Water Overflow Outlet 
           66  Shelf above the cage 
           68  Shelf beneath the cage