Diseases, hygiene and barrier nursing

How diseases are caused 2Pathogens 2How an infectious disease starts 4How pathogens leave an animal's body 4How infectious diseases enter 6

Levels of hygiene 7Vaccinations 7Appropriate levels of hygiene 7Cleaning and disinfecting routines 8Disinfecting and sterilising 10Disposing of waste 13

Barrier nursing 16Caring or nursing infectious animals 16Using isolation rooms 17Working in an isolation ward 18Barrier nursing sick tortoises 20Cage design principles 21

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How diseases are caused

Vet nurses are required to handle a range of very ill animals, some of which may be carrying a zoonotic disease. Great care must be taken to prevent contracting these potentially fatal diseases.

To understand how to prevent disease and/or reduce the risk of disease, it is useful to know something about pathogens, where they come from and how they cause disease.

PathogensPathogens are micro-organisms that cause disease. Examples of pathogens are:

bacteria

viruses

fungi

parasites—internal and external.

Some of these are capable of being transmitted to humans and can result in mild infection, serious illness or death. These are referred to as zoonotic diseases.

Examples of zoonosis are:

hydatid tapeworm

flea tapeworm

roundworm

hookworm

parrot fever (psittacosis)

Q fever

salmonella

ringworm

leptospirosis

sarcoptes mange mites

ringworm

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morbilla virus

lyssa virus.

leptospirosis.

The photo below shows an animal carer working in a dairy. This can be potentially dangerous for the carer as he is standing in a position where faeces and urine can be inhaled. An example of a zoonotic disease that is transmitted this way is leptospirosis. Vaccines are available against some of these and staff should make sure that they are vaccinated.

Pathogens can spread from one individual to another. They exist everywhere and some have a great ability to survive in the environment. Some do this by the production of highly resistant seeds (spores) that can stay dormant in the environment until conditions allow them to multiply. This means that the potential for infection by them is forever present in our daily lives.

However, not all micro-organisms are pathogens. Most are in fact beneficial, for example the ones that are used to produce foods such as yoghurt, cheese and beer. The bacteria that live in animals’ intestines and help in the digestion of plant matter are also not pathogens.

Hygiene is about the control of pathogenic micro-organisms, keeping them under control and preventing their entry into our bodies where they can cause disease.

How pathogens get into the body

Pathogens get into the body in the following ways:

mucous membranes

cuts through the skin

respiratory

gastro-intestinal tract.

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Diseases are transmitted by air (on wind) vapour and droplet (coughing and sneezing) and by direct contact (touching). The aim of cleaning and disinfection of areas where animals are kept is to minimise the transmission of these diseases, some of which include:

kennel cough

parvovirus

ringworm

mange.

How an infectious disease startsFor an animal to contract an infectious or communicable disease, the animal must come into contact with the infectious pathogen. The disease causing pathogen:

1. leaves from one infectious animal

2. enters an uninfected animal’s body

3. invades a particular system that it commonly attacks or, in some cases, it invades the entire body and affects the animal.

There are different ways that the pathogen leaves an infectious animal’s body (the reservoir) and then enters another body (the host).

The type of disease and where it resides in the animal’s body will determine how that disease leaves the infected animal’s body.

This will also determine how an animal contracts disease—the entry points (portals of entry) vary with different diseases. The entry site is often the site of infection—example, inhaled organisms cause respiratory infections. The pathogen needs to enter the host in enough numbers and by the right route to cause disease.

The susceptibility of the host will depend on their immune status—for example, you are more susceptible if you are tired or already sick.

How pathogens leave an animal's bodyOnce an animal has an infectious disease, the pathogenic organisms of that disease leave the animal’s body and enter the body of another animal or human. The pathogenic organism leaves the animal from the:

animal's respiratory system

- breathed out during normal expiration/exhalation

- sneezed out

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- coughed out

- mucous membranes

animal's digestive system

- faeces

- via the rectum—gas or discharge

- vomit

- saliva

- bites

- mucous membranes

animal's skin surface—integumentary system

- via the skin—sweat or sebaceous discharges

- off the skin—for example, external parasites

urinary system

- passed out with/in the urine

reproductive system

- vaginal discharges

- penile discharges and semen

- in utero from dam to offspring via the placental membranes

- parturition fluids during birth

- foetal membranes

- milk and secretions during lactation

- mucous membranes

circulatory system

- blood and associated fluids

- via vectors like mosquitoes and other external parasites acting as carriers.

Other ways that pathogenic organisms leave an animal’s body are through:

ocular (eye) discharges

wounds

congenital—animals born infectious

dead bodies—during decomposition.

How infectious diseases enterInfectious diseases can enter an animal via contact with:

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an infected animal

with the organism on a surface

bedding and housing, toys

food and water that is contaminated

food and water bowls and utensils

grooming equipment, brushes, rugs and coats

treatment equipment—non-sterile needles, surgical equipment.

Remember: It is not always just the animal that is at risk of contracting one of these infectious diseases; YOU can contract them too if the disease is a zoonosis. These diseases range in their severity.

There are different ways infectious diseases enter an animal’s body—called portals of entry—from:

direct contact—touching

indirect contact—airborne (on wind) vapour and droplets (coughing and sneezing)

contamination—food and water, surfaces

from the environment

from a disease carrier—vector.

Ways the pathogens gain entry into or onto the host:

respiratory—inhaled

digestive—ingested/swallowed, licks or bites

mucous membranes of the nasal passages, digestive system, reproductive and urinary systems

onto the skin surface (the integumentary)—eg wounds and bites

reproductive—male or female during copulation.

Important: Animals are unpredictable and can cause serious damage to handlers. Correct handling and restraint procedures will help reduce the incidence of disease and/or injury through being bitten and scratched. If injured at work by an animal, it is essential that you seek immediate medical treatment to cover the possibility of complications occurring.

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Levels of hygiene

The basics of disease control and prevention are:

maintaining appropriate hygiene—includes disinfection of environment and equipment, isolation of animals and diligent personal hygiene

wearing protective clothing—for example, face mask, gloves, aprons, overalls, boots, hair net or surgical gown

disposing of contaminants correctly—for example, syringes, needles, dressings, bedding, faecal matter, uneaten food, unused medications and disposable tests

keeping up-to-date with vaccinations.

VaccinationsSome diseases can be vaccinated against and it is recommended that staff be vaccinated to prevent contracting the disease. Vaccinations are available against the following:

tetanus

hepatitis

Q fever

lyssa virus

leptospirosis.

It is advised that you discuss a vaccination regime with your doctor as a means to providing you with the best protection.

Appropriate levels of hygieneThe level of hygiene required must be appropriate for each context. In the home context for example, general cleanliness is usually sufficient and there is no need to disinfect feed dishes or bedding. In a boarding kennel, where there are many animals coming and going, there is more need for disinfection. However, in a veterinary clinic, particularly in the operating theatre, a high level of hygiene must be used: sterility.

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Maintaining hygiene to reduce the risk of infectious disease involves:

using gloves and apron which are left in the cage room

changing Personal Protection Equipment between patients to prevent cross-contamination if there is more than one patient in the isolation ward

cleaning cages with antiviral solution

disposing of all newspaper and bedding in contaminated waste which ideally should be situated so you do not have to walk back through the clinic with the waste

wiping down door knobs and light switches used with the virucidal chemical

using a foot bath with a virucidal chemical on exiting the cage room.

For very infectious diseases that can be carried on clothing, the ideal situation would be to shower in and out and have a set of clothes to be worn in the room only.

Cleaning and disinfecting routinesWhen setting up a cleaning and disinfecting routine it is important to strike a balance between good hygiene and avoiding a too moist environment from constant washing because micro-organisms thrive in a humid atmosphere. You need to consider what you are using:

water supply

detergent

disinfectant

cleaning method.

Detergents

Detergents work by helping water to penetrate dirt. Detergents should have the following properties:

quickly soluble

non-corrosive

soften water

economical

non-toxic

biodegradable

good wetting action

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emulsify fat

dissolve organic matter

easy to rinse.

Daily cleaning

For most animals that are being boarded, one thorough cleaning and disinfection daily should be sufficient. This is better than three minimal floor wipes with a cloth or mop and bucket. When animals soil their kennel during the day, when not in runs, this should be cleaned up immediately and dealt with locally.

When an animal leaves the kennel its accommodation can be cleaned and disinfected and preferably left empty for a few days. All the bedding should be removed and either disposed of or disinfected.

Here is a comparison of different cleaning methods:

Dusting and sweeping:

- this removes dust, dirt and debris but will fling some into the air, where it can be inhaled by man and animals, or will simply settle again later. This is NOT ideal.

Mopping:

- dry mopping is the same as dusting

- wet mopping is better for removing dust and debris

- disinfectant can be included; but mop heads can harbour micro-organisms

- mop heads may leave the area wet, leading to problems in reception

- is hard to get into corners.

Vacuuming:

- this is the method of choice for dusting and initial cleaning

- effectively removes dirt and dust

- ‘wet’ vacuums can include liquids

- can get into corners

- can do shelves and benches

- avoids airborne dust problems

- should use liner bags to avoid liberation of dust when emptying.

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Selecting disinfectants and antiseptics

Each product will have a manufacturer's data sheet which lists the uses and suitability for the job required. Some of the main factors which should be taken into account when choosing a product are:

the intended use of the product—eg for kennels, runs or equipment

the product activity against specific micro-organisms

the required period that it takes for the chemical to kill the target organism—contact time

known local conditions—eg hard water

the product should be safe for staff and animals—non-irritant, non-toxic and non-corrosive

stability of product when in storage

must be odourless or have a pleasant smell

ease of use—dispensability in water if diluted

economy of use—cost per made up litre of ready to use solution.

Note: Some products are effective for kennels but may stain bedding. Some animal species are sensitive to some types of disinfectant—eg cats are sensitive to phenol. Chlorine products irritate the nasal passages and eyes of both animals and humans.

Disinfecting and sterilisingTo prevent the pathogenic micro-organisms from contaminating wounds—example, during surgery—we have to practice good hygiene with the use of methods that prevent these micro-organisms gaining entry into our bodies.

Equipment such as buckets, brooms, shovels, mops, kitchen utensils, food bowls, beds and bedding, must all be cleaned and disinfected regularly. You need to:

Wash them first to remove organic material.

To disinfect, soak in an appropriate disinfectant for the material. Note: Some materials, can be corroded by certain chemicals at the recommended time and strength.

Rinse thoroughly.

Dry the equipment before storing it.

The steps for cleaning include:

1 dry cleaning

2 wetting all areas

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3 applying detergent using physical effort

4 rinsing

5 drying

6 disinfecting

7 rinsing

8 drying

9 checking.

Physical methods

Physical methods include using:

Dry heat:

- Mops, cloths, gowns, towels etc should always be stored dry.

- Sterilisation can be achieved with dry heat but this requires prolonged heat—glassware for one hour at 170oC and sharp instruments for three hours at 150oC.

Moist heat:

- Water at 60oC or above has a cleaning effect only. If a detergent and mechanical action are used over time it can approach disinfection but never sterilisation.

- Boiling water at 100oC for 20-30 minutes is effective for disinfection only.

Steam:

- To sterilise it also has to be under pressure; this is called autoclaving.

- Steam under pressure kills spores within three minutes and makes minimal damage to fabrics and instruments.

- Steam must penetrate the pack and condense onto the instruments in order to heat them up for sterilising.

- Use porous packing.

- Do not overload the autoclave.

- Pack it correctly.

Ultrasonic vibration: Ultrasonic vibration has a cleaning effect but does not achieve disinfection.

Ultraviolet radiation: Ultraviolet rays that are invisible to the human eye will destroy many micro-organisms, particularly bacteria. However, they do not penetrate therefore can only be used for sterilising surfaces.

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Ionising radiation: Other forms of radiation—gamma, alpha, beta, X-rays—can also be used for sterilisation but are limited due to cost and safety. Their use is mainly in the sterilisation of plastics and rubber goods which cannot be heated.

Filtration: This is used to purify water and air. Surgeons use masks to filter out any micro-organisms they could breath onto the patient. These masks are only effective whilst they are dry.

Dilution:

- Physical dilution—for example washing with water or other liquids—achieves cleaning.

- We use this method when we flush out an abscess, or irrigate wounds.

Chemical methods

The action of chemical disinfectants is dependent upon being in direct contact with the target micro-organism. This means that all traces of organic material such as dirt, grease, faeces, urine, blood and vomit must be physically removed from the surface prior to disinfection. Otherwise the chemical agent will be unable to come into contact with the micro-organism.

Begin by removing solids with a shovel and scraper, then hose out the kennel with water and then use a detergent and scrub with a stiff, dense bristle brush. A stiff bristle broom could be used for daily scrubbing but a hand brush would be more effective for weekly or departure cleaning.

Detergent type disinfectants are available that are designed to clean and disinfect in one application (with scrubbing). They are often used in kennels for daily application where no disease problems exist, as they shorten the time of the cleaning process.

Chemical methods include using:

liquids—see Table 1 in the Appendix

gases:

- Ethylene oxide: This gas is used for sterilising instruments that cannot stand heat. It is extremely toxic and can only be used by trained personnel.

It has been replaced by another type of gas steriliser that uses hydrogen peroxide as the sterilise agent. The machines for hydrogen peroxide gas are extremely expensive ($180,000) and the packaging that has to be used is expensive but the gas is much safer to people.

- Aldehydes: Formaldehyde gas is used to fumigate rooms, eg operating theatres if they are having a problem with post-

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surgical infections that is suspected to be coming from the environment in the theatre. The gas is very toxic and irritant to the mucous membranes.

Precautions when using chemical disinfectants

When using any chemicals, whatever type, care should be taken to handle them in a correct manner, this includes:

storing them in the original container with the lids fully secured

keeping away from animals and children

wearing protective clothing when recommended and taking care to avoid contact with the skin

washing hands thoroughly after use, particularly before eating and drinking

using the correct concentration.

There are both chemical and physical methods of disinfection and sterilisation.

Disposing of wasteThere are many different types of waste generated in a veterinary clinic, some of which could be harmful to humans and/or animals:

biological—eg animal bodies and parts, faeces, urine, hair/fur, blood, tissue samples, bacterial agar plates and dressings

chemical—eg disinfectants, detergents, flea chemicals, shampoos, drugs, X-ray chemicals, cancer drugs and clinical pathology chemicals

sharps—eg glass slides, needles and scalpel blades

ordinary household type waste—eg paper waste, plastic and glass

contaminated waste, includes anything that can cause disease to humans—eg carcinogenic chemicals, zoonotic waste

radiographic chemicals—always use waste disposal containers for contaminated waste. Never flush down drains

surgical waste—should be put in plastic bags and then a hazardous waste container.

The method you use to dispose of your waste should aim to prevent harm, in other words:

Avoid transmission of disease.

Avoid contamination of waterways and water tables.

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Prevent vermin growth.

Prevent exposure of human population to toxic compounds.

Prevent zoonotic disease.

Prevent injury to personnel and local population.

Aesthetic disposal of client's pets.

Disposing of waste safely includes:

wearing protective clothing—eg gloves, aprons or gumboots

taking appropriate vaccination—eg tetanus, hepatitis, rabies or etc

follow recommendations for disposal of harmful substances—eg cytotoxic waste, has to be double bagged, sealed and incinerated at high temperatures

disposing of contaminated waste appropriately—sharps and infectious disease samples need to be disposed of in an appropriately labelled waste receptacle and then either incinerated or disposed of in a special spot at the local tip

complying with council regulations regarding which waste can be disposed of with other ordinary household waste—down the sink, in the carcass section of the local tip, etc.

Disposing of needle sticks and sharps

Sharps include scalpel blades, needles and glass. Needles and syringes should be disposed of as an entire unit as most injuries occur during resheathing of needles prior to removal from syringe. Note: In hospitals for humans no one is allowed to resheath a used needle as this is the time when most needle stick injuries occur.

To correctly dispose of needles and sharps, it is essential to use a sharps container that has the following features:

walls that cannot be penetrated by the needles

crush proof

leak proof

may be destroyed by incineration

good sized opening to prevent injury or contamination to the hand during disposal

be labelled ‘Contaminated waste: Sharps only’, as in the photo below

a screw cap lid that is secure or an attached lid, as in the second photo.

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Barrier nursing

Caring or nursing animals with potentially fatal, infectious diseases is central to your work in a veterinary clinic. Whether or not you are a nurse, your role in caring for these animals is still classified as nursing.

An important aspect of working with animals with infectious diseases is that it is done in a way that prevents the spread of the infectious disease to other animals within the facility. This is called barrier nursing.

Caring or nursing infectious animalsThe day-to-day duties of a veterinary nurse or animal carer centre on treating sick and healthy animals. This means not jeopardising the health of any animal where it is at all preventable by using the principles of good hygiene.

Diseases can survive outside of the body of the diseased animal. The disease can exist in the environment where the sick animal is being housed—the cage or housing. If you have been holding an infectious animal or used equipment with the animal, your hands, clothes and equipment can transfer the disease to other animals or parts of the clinic or animal environment.

An example

Let’s say an owner brings a healthy seven week old puppy for its first set of vaccinations. Prior to this puppy, was a patient that had parvovirus. It is vital that the staff handling the patient and any equipment used on the patient—including items such as the consultation table—are disinfected. If this hygiene is not practised, imagine the possible consequences for the healthy puppy.

Remember vaccines do not work immediately and in young animals they are not fully immune until the course has been completed—this make them all the more susceptible to disease. So, no matter how busy it gets in the clinic, take the time to keep up with good hygiene practices.

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Using isolation roomsAnimals with infectious diseases should be housed in an isolation room. The room should be away from the main traffic area of the clinic. Always treat and care for the sick animals in the isolation room after you have attended to the healthy animals.

This photo shows an ideal isolation ward for a group of small animals

The purpose of barrier nursing is to make sure that the disease stays in the isolation room. For this to be achieved, you need to consider carefully how you:

will dispose of any items that you have used in the isolation room

will enter and exit the isolation room

can prevent others, both animals and humans, from risk of infection.

Items used in the isolation room

Any items such as drugs, bedding and food that are taken into the isolation room should put into the garbage; it should not come out of the room any other way.

Garbage should not be carried back through the clinic but disposed of through another route. In infectious disease wards for humans, all waste is incinerated. However, this is generally not necessary for most companion animal diseases we deal with in Australia.

Prevent risk of disease to others

Dogs, especially those that have had vomiting and diarrhoea, should be washed thoroughly before discharge to remove any traces of discharge that may be harbouring the virus or bacteria. This also makes a much better impression on the owner!

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Try to remember that it is not just the other animals in residence that are at risk of these infectious diseases. You could easily:

become infected yourself if the disease is zoonotic

pass the disease onto another human if it is zoonotic

take the disease outside of the facility, which means you may take it home and affect your own animals or other animals that you come into contact with.

Working in an isolation wardWhen working with animals in an isolation ward, try to avoid stress and work quietly. Talking gently and soothingly to the animals as you work may help to settle and relax them. Once the animals become familiar with the sound of your voice they will look forward to your presence. Other daily practices you should consider are:

Each cage should have its own food and water containers, litter tray etc. These should always be thoroughly cleaned, disinfected and allowed to dry before reusing.

Wash hands before you begin working with another animal or use separate gloves for each cage.

Using disposable bedding will reduce the risk of a disease being transferred on blankets.

Remove all waste from the room for storage before disposal.

Below is a photo of a veterinary nurse dressed to work in an isolation ward.

Entering and exiting the isolation room

Plan each trip so you only have to enter the isolation ward once:

Have specific equipment all stored separately from general equipment it should be stored in the isolation room. It is all cleaned and left in the room, reducing traffic in and out of the room and is on

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hand when needed—for example clippers, catheters, scissors, bandages, stethoscope, thermometer, mops, buckets, bedding and sharps container.

Take all medications to the isolation room to reduce the need for leaving the isolation room once you have entered.

Ideally, the nurse should enter another room through a foot bath of a virucidal disinfectant.

The photo below shows an entrance to an isolation ward. Notice that a ’No entry’ sign on the door is used and there is a blue disinfectant footbath. There is also a sign that shows how to make up the correct dilution of chemicals for the footbath.

The nurse should also change out of their day clothes and shower. They should also wear a set of clothes that stays in the isolation ward. These procedures are a little extreme for most dog and cat diseases that occur in Australia, but the concepts are worth remembering.

You should at least try to change your shoes, wear a waterproof apron and gloves which stay in the room and wash your hands thoroughly in antiseptic. This is to stop you carrying the disease back out on your hands or clothes.

Ideally, everything that enters the room should be thoroughly disinfected before re-entering the clinic—including the nurse's shoes, hands, utensils, etc.

Extra considerations

When caging animals, especially sick ones, consider the likes and dislikes of everyday living according to their species. A very good example of this is cats:

Cats like to sit up on a shelf and survey the world.

Try not to have hidey holes where they can disappear from view unless you can check them daily as cats will disappear when sick.

Check their litter tray/faeces daily for the presence of blood, diarrhoea, worms etc.

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Barrier nursing sick tortoisesSome species of tortoise are highly susceptible to epidemic disease while others appear to be immune. Certain species may be carriers. Tortoises which are not found together in the wild should not be kept together in captivity. All tortoises should be isolated when signs appear.

How disease is spread from tortoise to tortoise

Disease can be spread by head-to-head contact, spitting, coughing, sneezing, biting, courtship and copulation. There can be indirect spread if tortoises eat or drink from the same dishes, bath in the same water, eat or walk through urine or faeces or simply walk over the same ground.

Flies can carry disease from one pen to another. Food rejected by one tortoise should never be offered to another. Owners can transfer infection by handling tortoises, particularly if an animal urinates, defecates or bleeds while being held.

Always wash your hands and change or clean and disinfect contaminated clothing before handling another tortoise.

Sneezing and coughing expels germs into the air with enough force to travel several feet. Germs from dried faeces, urine and saliva are carried on dust particles. Ideally, pens should be several feet apart, with boundaries several times the height of the tortoises. Vegetation acts as a natural filter.

Even sick tortoises should be kept outside if possible to maintain natural conditions. If an indoor vivarium—a place that simulates the natural environment of the animal—is used, it should have fitted forced air ventilation and the animal should be transferred to more natural conditions as soon as possible.

Barrier nursing practices

The following practices and concepts of barrier nursing are the same for any species of animal—including humans too!

Always use clean food utensils and tools, and wash hands between handling different tortoises. Do not use the same equipment—drinking bowls etc—for different tortoises, and do not use for the same tortoise without cleaning and disinfecting. Immediately after use, put items into a pot of disinfectant. Break disposable items to prevent them being used again.

Reusable items should be first washed and rinsed, then soaked overnight in an approved antibacterial solution. Then they should be rinsed thoroughly in clean water before use.

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Wear disposable gloves and apron when handling sick tortoises, and plastic overshoes if you have to walk into their pens. Polythene bags over the shoes are adequate. Wear separate clothes for dealing with sick and healthy tortoises, and wash them daily.

Check each pen daily to remove faeces and uneaten food, then disinfect the area with iodine or a 70% alcohol solution. Garden tools must be disinfected between pens. Wash off visible debris, immerse in diluted bleach for five minutes, rinse and wipe dry. Rubbish should preferably be burnt but can be wrapped and put in a dustbin. Do not put it on a compost heap.

Germs can contaminate soil for years so never re-use a pen occupied by a sick or suspect tortoise without disinfecting it. Remove and burn all vegetation.

Dig up the top three inches of soil and sterilise by burning, turning the pile often until each batch is thoroughly 'cooked'. Small amounts may be spread on trays and put in an oven at 250°C for two hours, or in a pressure cooker at 15psi for twenty minutes. The soil can then be returned to the tortoise pen and replanted.

Rocks, wood, concrete and other hard surfaces should be cleaned with detergent, rinsed and swabbed with diluted bleach. Work it well into corners and crevices and rinse off after five to ten minutes.

Occupied quarantine pens should not be kept sterile. The organisms in air, soil and vegetation are important to the tortoise. Simply sterilise any area suspected of harbouring the epidemic disease.

Cage design principlesRegardless of the species of animal, the design of the cages within a facility needs to be considered to deal with an outbreak of infectious diseases. The room should be located so that it is not in a main thoroughfare and so that all waste can be disposed of without going back through the clinic. The design needs to take into consideration for the design and layout of housing:

Cage room design: Cages should face each other and be at least one metre apart—the water droplets in which viruses are carried cannot travel that far.

Individual cage design:

- Prevent nose to nose contact between individually caged animals by having solid walls, floors and ceilings.

- Floors and walls should be made from an easy clean, non-absorbent material that can withstand constant cleaning.

- Floors and walls should have rounded corners to prevent dirt accumulating in hard to clean corners.

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- Each cage should have its own drainage that is not shared with any other cages.

Environmental control:

- Ventilation is critical for the prevention of disease in the cage room area. Ideally, all air should be filtered and then vented outside and not back into the clinic to prevent airborne diseases spreading into the clinic. Ensure that the room has at least 20-24 complete air changes per hour to prevent build up of viruses and bacteria in the air.

- Ventilation points should be placed at opposite ends of the room so that one is a fan that sucks air through the room and the other is a vent allowing fresh air in. This arrangement helps to prevent drafts.

- Ensure the temperature is thermostatically controlled and even with no sudden rises or falls or big fluctuations during day and night.

Large establishments: If possible, have a number of cage rooms rather than one big one, so if there is an outbreak the room can be closed off and treated like an isolation room.

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Appendix: Table 1Chemical group Example Spectrum of activity Problems Main use Residual Activity

Iodine compounds

 

 

 

Povidone-iodine

5 or 10% solution

7.5% scrub

 

Bacteria, viruses, fungi, protozoa, yeasts

 

detergent in the scrub is cytotoxic.

corrosive to metals

inactivated by organic matter

contact dermatitis and skin irritation which can increase post-surgical wound infections.

surgical prep

wound irrigation

 

4-6 hrs

 

Aqueous iodine As above cytotoxic and can increase infection due to cell damage 

stains 

Wound lavage  

Tincture of iodine As above only for intact skin as it is too irritant

2% iodine in 50% ethanol

 

Bisbiguanide Chlorhexidine as a scrub solution

As above, except does not kill protozoa

eye irritation

cytotoxic

use for pre-surgical prep of skin, wound therapy

disinfection of instruments

unaffected by alcohol

two days (binds to a protein in the skin surface

onset of action on the skin is rapid

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Phenols Hexachloraphene

Dettol

Bacteria neurotoxicity from dermal exposure

cytoxic

slow onset of action when applied to the skin

inactivated by alcohol

up to two days

Alcohols Isopropyl alcohol 50% or 70% ethanol

Bacteria and some fungi neurotoxic

cytotoxic

used alone or as a tincture 

inactivated by organic matter

none as it evaporates

Aldehyde Glutaraldehyde

Formaldehyde

Bacteria, viruses, yeasts, spores (but only with prolonged contact—3 hours)

skin irritation

inhalation

irritant hypersensitivity

2 % solution used for ‘cold sterilisation’ of objects

must be thoroughly rinsed off due to toxicity

none

Quaternary ammonium compounds

Benzalkonium chloride 

Savlon

Bacteria dermatitis

hypersensitivity

toxic if ingested

Used for disinfection none

Hydrogen peroxide   Minimal bactericidal action

Cytotoxic Should only be used once at the first irrigation of a contaminated  wound

 

Chlorine compounds Hypochlorite (bleach)

Chloramines (halamid)

Bacteria, viruses, fungi cytotoxic

can damage some surfaces by bleaching

chloramines are less irritant to the skin

often used against ringworm

none

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