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LABORATORY ANIMALS

1. State four uses of laboratory animals

Lab animals are used in different areas, including:

• Developing and testing medicines and vaccines for humans or animals
• Research how animal and human bodies function
• Education and classroom demonstrations and experiments
• Safety testing chemicals. Checking their possible effects on human health or the environment

2. State any four reasons for keeping laboratory animals

This is because

• It is ethically impossible to use human or human specimens in doing this experiments but it is possible to obtain similar results using laboratory animals.
• These animals are easy to  maintain in a laboratory environment  
• have short life expectancy  which enables  the effect  of a lifetime  to be observed  in relatively short life time
• They give birth to several offspring that make it easy have sufficient population within a very short lifetime.

3. Give   four advantages of drosophila in genetic studies

Drosophila melanogaster is a popular experimental animal because

• It is easily cultured in mass out of the wild,
• Has a short generation time,
• Mutant animals are readily obtainable.
• Their chromosomes are few(8) and easy to be used in genetic studies

4. Distinguish between male and female drosophila

• Male and female drosophila differ in many ways: Only males have a sex comb, a fringe of black bristles on the forelegs. The tip of the abdomen is elongate, somewhat pointed in females, and more rounded in males.
• The abdomen of the female has seven segments, whereas that of the male has only five segments.

5. List four methods of humane killing of a laboratory animals.
6. chemical methods
   1. Inhalation of carbon dioxide (Co2)

Suitable for small rodents and birds; animals should be exposed to an atmosphere of 30 % CO2 (to ensure loss of consciousness) which is then increased to 70% to kill the animals. This may be achieved by placing the animal in an air-filled container and then allowing the gas to flow into it so that the concentration rises to at least 70% and is maintained there for at least 3 minutes. Animals may be left in the container until rigor mortis is observed, or they may be removed and death ensured by exsanguination or dislocation of the neck, and confirmed dead.

1. Inhalation of volatile anesthetic

It is suitable for small rodents where the animal is exposed to a volatile anesthetic substance leading to its overdose and hence death. When using an anesthetic overdose there should be no contact between the animal and the anesthetic in its liquid form. The procedure should always be carried out in a fume cupboard or a well-ventilated area so that the operator is not subjected to prolonged exposure to the vapor fumes.

• Injection of anesthetic

This method is Suitable for all species. It is a method of choice for larger species; an overdose of anesthetic substance should be administered intravenously or intraperitoneally and be sufficient to ensure rapid unconsciousness and death.

Exsanguination

Exsanguination is the action or the process of draining or losing blood. The animal is first rendered insensitive to pain by various methods e.g. sedation or aesthetic

1. Physical methods

(i) Dislocation of cervical vertebrae – suitable for small rodents, small rabbits and larger birds. The animal`s head is restrained between   the fingers and then twisted  by turning it backwards  so as to break the spinal cord

1. ii) Concussion by striking the back of the animal’s head. This method is restricted to animals that are handled easily and that have relatively thin skulls, i.e. small rodents and smaller birds.

iii)Decapitation used for rodents where other methods would be unsuitable. It is the complete removal of the head from the body. This method must only be carried out using a specially designed and properly maintained guillotine.

Iv.Pithing

The soft skull of the animal is pierced using a sharp needle then stirring up the brain. Mostly done on frogs and toads

v.Immersing the animal in the already boiled and cooled water  The animal is dropped into oxygen free water and therefore the animal will die slowly due to lack of oxygen. This can be done on frogs, fish reptiles etc.

NB: It is essential to ensure that the animal is dead before disposal. The animals must be kept and observed for several minutes after all signs of life have ceased. Alternatively, the animal’s neck should be dislocated or the animal may be exsanguinated. Preferably, animals should be disposed of on site by incineration. If this is not possible, care should be taken to prevent exposure of the carcasses to the public. Infected, toxic or radioactive carcasses must be disposed of in such a manner that they do not present a hazard.

6. Describe care of laboratory animals

The health and well-being of the animals depend on the care, human attitude of the animal-keepers (staff) of the animal house. To keep animals healthy, the staff has to look after cleanliness of the animal rooms and cages, provide proper food and water, to move to a cooler or warmer place and to provide air.

The general principles are outlined:

 

1. .Diet and  Fluid:

A balanced diet containing carbohydrate, fat, protein, vitamins and trace elements is to be given regularly. It is commercially in the form of cubes or pellets. Small quantities of green stuff are also to be supplied.

They are to be provided with plentiful supply of fresh clean drinking water from a bottle (250 ml capacity) attached to the outside of the cage. The water is led in a 6-9 mm glass tubing through a rubber bung to an accessible position inside the cage; the outlet tubing is about 3 mm.

1. Cleanliness:

Cleanliness of room and cages is essential unless they are kept in considerable risk of epidemic diseases. Animals, when breeding, should not have their cages changed too often.

Clean cages should be used. Cages may be boiled in soapy water; alterna­tively, to be kept immersed in a solution of disinfe­ctant such as 3% Lysol. Lysol, however, should not be used in cleaning the cages of rabbit because its smell distresses the animals.

1. Litter:

A layer of absorbent material (e.g. soft wood sawdust’s, sugarcane piths) should be spread to a depth of 1/2 to 1 inch (1.25-2.5 cm) on the bottom of the cages.

1. Cages:

Each species of animal require its own type of cage. It should be large enough for movement and some exercise of the animal.

1. Labelling:

Every case should be provided with a holder or socket for a small card of 6-9 cm for record of the experiment (date, identifying marks of animal, nature of experiment and specimen).

1. Ventilation:

Animal room should be air-conditioned; or at least ten changes of air in each hour are needed.

1. Humidity:

Humidity of animal house ranges between 45% for rabbits to 65% for mice.

 

 

1. Marking animals:

White or light coloured animals are marked by staining the fur with a strong dye (e.g. carbol fuchsin, eosin). Rabbits may be marked in ears with a needle dipped in India ink. Rats and mice are punctured in ear and fowls are marked by numbered metal tags on legs clipped through the loose skin of the wing.

1. Detection of disease in animals:

A routine tour of inspection of the animals should be made at least once a day with attention to the general condition of animals, amounts of food and water consumed and the nature of faeces. To see nose movements of the animals and to see any animal remaining quiet and still. Such animals may be separated and investigated for the cause of disease.

1. Recording animals’ temperature:

Clinical thermometer is liberally smeared with sterile petroleum jelly and the blunt-ended rectal thermometer is introduced into the rectum or vagina to a depth of about 3 to 3.5 cm.

1. Prevention of disease:

Newly arrived animals to be kept in a special quarantine room and kept under observation for 10-14 days. Animals falling sick during the period should be kept in quarantine and necropsis must be done for finding out the cause of the illness.

Animal infected experimentally with bacteria or viruses should be kept in separate isolation rooms to prevent spread of infection to other animals.

1. Insect pest:

Bed bugs, fleas, lice, mites, ticks, flies, mosquitoes and cockroaches may all infest the animal house. These can be controlled by 0.5% insecticidal sprays or 10% DDT.

7. Outline the humane killing of mice in the laboratory
   1. Breaking of spinal cord

The animal is held by its hind legs and its cervical region or backbone is cracked sharply across the edge of a table.

1. Overdosing with chloroform, Nitrogen ,Carbon monoxide or Suffocating with CO₂

8. Describe methods of handling of a rabbit laboratory animals giving examples of animals handled in each case

Rabbits should be handled with care. The rabbit is picked up from cage with the ears by one hand in a firm grip and another hand is placed under the hindquarters to support the weight and then lifted gently. After removing from cage, the animal is placed in a non-slippery place, as it otherwise feels insecure and becomes frightened.

9. Give five examples of zoonotic diseases that can be transmitted through handling of laboratory animals

Rabies, chicken pox, Anthrax,

10. State five methods of controlling animal diseases in the laboratory

• Vaccination
• Proper nutrition
• Proper  housing with good lighting ,ventilation and drainage system
• Using protective clothing when handling lab animals
• Culling or isolating immediately  diseases or infected animals

11. List any four zoonotic laboratory animal disease

• Viral infections, such as contagious ecthyma, the hepatitides, and Cercopithecine herpes virus 1 (Herpes B); rickettisal diseases, such as Q fever and cat scratch fever;  
• bacterial diseases, such as tuberculosis, salmonellosis, and shigellosis; •
• protozoal diseases, such as toxoplasmosis, giardiasis, and cryptosporidiosis; and •
• Fungal diseases, such as dermatomycosis.

12. Name two protozoan diseases that affects guinea pigs in the laboratory

The guinea pigs are affected by protozoan diseases (coccidiosis, toxoplasmosis),  also by bacterial infections such as pseudo tuberculosis, S. typhimurium, abscess in lymph node (Streptococcus group C), hemorrhagic septicaemia (P. multocida) and viral pneumonia and paralysis

13. Suggest ways for preventing spread of infectious diseases in laboratory animals

Disease outbreak is minimized in clean healthy cages but in case of   disease outbreak, only experts should be allowed to diagnose and treat the diseased animals.

sick and diseased animals should be culled, isolated and humanely killed and the cages sterilized.

Laboratory animals should be obtained from accredited suppliers to avoid chances and risks introducing epidemics in the cages.

Newly arrived animals to be kept in a special quarantine room and kept under observation for 10-14 days. Animals falling sick during the period should be kept in quarantine and necropsis must be done for finding out the cause of the illness.

Animal infected experimentally with bacteria or viruses should be kept in separate isolation rooms to prevent spread of infection to other animals.

 

14. State four benefits of proper ventilation in a laboratory animal house .

Laboratory animal facility ventilation should balance air quality, animal comfort, and energy efficiency to provide cage environments that optimize animal welfare and research results. Conditions that optimize animal welfare minimize unintended stress factors that can significantly affect research results.

15. Explain reasons  for sexing laboratory animals

To determine the sex of the animal

To determine any genital malformation or abnormalities of the animal external sex organs

To determine whether the animal is fit to be used for breeding purpose

16. Define  

• Humane killing
• Euthanasia

17. Differentiate between anaesthesia and euthanasia

Anaesthesia and euthanasia are two distinct concepts related to medical and veterinary practices. Here’s a brief differentiation between the two:

Anaesthesia:

Anaesthesia refers to a medical procedure used to induce a temporary loss of sensation or consciousness during surgical procedures or other medical interventions. Its primary purpose is to eliminate pain, provide muscle relaxation, and create a state of unconsciousness or sedation. Anaesthesia allows medical professionals to perform procedures without causing pain or distress to the patient.

During anaesthesia, various medications, such as anaesthetic gases or intravenous drugs, are administered to achieve the desired effect. The patient is closely monitored throughout the procedure by trained anaesthesiologists or medical professionals to ensure their safety and well-being. Anaesthesia is reversible, and patients typically recover consciousness and sensation once the procedure is completed.

 

Euthanasia:

Euthanasia, on the other hand, refers to the deliberate act of ending a person or an animal’s life to relieve suffering, particularly in cases of incurable or terminal illness, severe pain, or irreversible conditions. It is a highly controversial and ethically debated practice, and its legality and regulations vary across countries and jurisdictions.

Euthanasia can be classified into two main types:

Voluntary Euthanasia: This involves the explicit and informed request of the individual who wishes to end their life due to intolerable suffering or poor quality of life. It is typically carried out with the assistance of a medical professional or under strict legal regulations.

Non-Voluntary Euthanasia: Non-voluntary euthanasia is performed when the patient is unable to give consent, such as in cases of severe disability, irreversible coma, or advanced dementia. The decision to end the person’s life is usually made by family members or legal guardians based on the individual’s previously expressed wishes or presumed best interests.

Unlike anaesthesia, which aims to provide pain relief and temporary loss of consciousness for medical procedures, euthanasia involves intentionally ending a person or animal’s life to alleviate suffering or maintain dignity in end-of-life situations.

It’s crucial to note that the regulations and ethical considerations surrounding euthanasia vary significantly between different countries, and there are ongoing debates and discussions on the topic worldwide.

 

18. Give four reasons why euthanasia is carried out in the laboratory

In laboratory settings, euthanasia is sometimes carried out for specific reasons related to animal welfare, scientific research, or experimental protocols. Here are four reasons why euthanasia may be performed in a laboratory:

• Humane Endpoint: Euthanasia is carried out as a humane endpoint for animals involved in scientific studies or experiments. When an animal reaches a predetermined endpoint, such as the completion of a study or the onset of severe illness or distress, euthanasia is performed to prevent further suffering.
• Tissue Collection: In some cases, euthanasia is conducted to obtain specific tissues or organs for research purposes. The euthanasia method is chosen to ensure the preservation and quality of the desired tissues or organs for subsequent analysis or experimentation.
• Disease Control: Euthanasia may be necessary to control the spread of infectious diseases within the laboratory animal population. In cases where animals are affected by highly contagious or untreatable diseases, euthanasia can be performed to prevent further transmission and reduce suffering.
• Genetic Line Management: Euthanasia is sometimes employed to manage genetic lines or populations of laboratory animals. This can involve the removal of animals that do not meet specific breeding or research criteria, such as animals with undesirable genetic traits or surplus animals that exceed the facility’s capacity.

It’s important to note that the use of euthanasia in laboratory settings is strictly regulated and governed by ethical guidelines and animal welfare regulations. The decision to euthanize animals must be based on careful consideration of scientific, ethical, and animal welfare principles, and it should be performed by trained personnel following approved protocols and guidelines.

 

19. State four ideal characteristics of an an euthanizing agent

The criteria that should be used in selecting an agent or method for euthanasia include:

 

• Should instantly cause cack of pain perception by the animal.
• Should be relativly rapidity and irreversibility.
• Able to cause minimal stress, apprehension, and fear in the animal or in nearby animals.
• Should cause minimal interference with experimental protocol.
• Should simultaneous interruption of consciousness and reflex mechanisms.
• Should be safe to the user..
• Should be reliable.
• Should be efficient and ease of procedure.
• Should be cost-effective  and available.
• Should cause minimal psychologic stress for attending personnel and observers.
• Shaould have minimal adverse environmental impact.
• Should have minimal potential for human drug abuse.

20. Outline the stunning method of humane killing of a rabbit

The stunning process ensures the animal is unconscious and insensible to pain before being bled out at slaughter. Common stunning methods include electrical stunning, captive-bolt stunning or the use of carbon dioxide gas. Following stunning, the animal is bled and remains unconscious until it dies due to blood loss. Persons responsible for the stunning animals must be appropriately trained and competent in their required tasks to ensure that every animal is humanely stunned.

1. Percussive

Percussive methods cause unconsciousness by administering a severe blow to the skull of the animal, with or without penetration of the skull. Both penetrative and non-penetrative captive-bolt stunning methods must be followed as soon as possible by bleeding to kill the animal. Shooting an animal with a freebullet to the head is considered a percussive method which also kills the animal.

1. Electrical stunning

An electrical stunning device (applied to the head only) must pass sufficient current through the brain of the animal to interrupt normal brain activity and render the animal immediately unconscious. Electrical stunning (or electronarcosis) is reversible as it disrupts normal brain function for a short time only. An electrical stunning system requires the correct voltage, current and application time to be delivered for the stun to result in instantaneous and painless unconsciousness.

1. Carbon dioxide

Carbon dioxide gas is used to induce unconsciousness. As the animal inhales the carbon dioxide gas, blood oxygen level decreases resulting in a loss of brain function and eventual brain death. Animals must remain at the point of maximum gas concentration for a specified period of time to ensure they are irreversibly unconsciousness. There are welfare concerns about carbon dioxide stunning because it irritates the respiratory tract.

 

21. Discuss the laboratory mice under the following  headings
    1. advantages as a laboratory animal

They are easy to maintain in a laboratory environment, reproduce faster and have short life expectancy which enables the effect of a lifetime to be observed in relatively short life time. Laboratory animals   are generally small animal that can be easily handle in the laboratory environment.

1. feeding

Mice are omnivore’s animals, which feed on green vegetables, grains and pellet supplements. They eat most of their daily ration in the dark. Their incisors and molars wear down and regrow with use.  It is important to check that each mouse has the required teeth in good order or else they risk under-nutrition or malnutrition.

1. sexing

Sexing is done by observing the distance between the anus and genitals. This distance is usually greater in the male than in females. Avoid handling a postpartum female or her litter for several days after birth.

1. breeding cycle

They mature and mate when at the age of between 6-8 weeks old. At this time, they should be kept in threes (trios) per cage i.e. one male: two females. Avoid inbreeding as these may result in drop in average litter size

Their estrous circle last between 4-5 days with a gestation period of 19-21 days. They give birth to a litter size of 7-8 and have a litter frequency of 5 times yearly. The young ones should be weaned at 21 days.

1. Handling and transporting

• Handling and transporting at this time could cause the mother to reject her young or eat them. This risk can be reduced by:
• Wearing plastic gloves, to eliminate human scent.
• Place the dam in a separate cage while the litter is handled.
• Rub the pups with bedding material from the home cage.
• Taking a mouse by the tail is a common way of lifting the animal. However, this could be stressful and creates antagonism toward the handler. While the mouse is inside the cage, take the base of the tail between your thumb and index finger, then pick the animal up by the tail. Support the animal’s weight on your arm or the cage floor; never allow the animal to dangle.

Other methods for routine handling are to:

• Cup the mouse in your open hand, but note: the mouse will try to escape (and will sometimes succeed).
• Handle while inside a home cage tunnel.
• Collect the mouse using the tunnel and transfer to your open hand.

To restrain the mouse, place the animal on a rough surface such as a cage lid. Hold the loose neck skin between your thumb and index finger, and then lift the mouse securing the tail between the fourth or fifth finger and palm of the same hand. Your other hand is free for injections or other procedures. To pick up newborn or mice less than two weeks old, take the loose neck/shoulder skin into thumb and index finger or cup the pup in your open hand.

22. Distinguish between

• Concetrates and suplimentary feeds

Concentrates are the energy-rich grains and molasses, the protein- and energy-rich. Supplementary feeds  are additives such as vitamin supplements, and mineral supplement that are  lacking in energy or proteins.

• Ad libitum and restricted feeds

Ad libitum feeding means that the diet is available at all times. Restricted feeding refers to restricting the amount of food while still ensuring nutritional adequacy.

• Pelleted and extruded diet

Pelleted diets are pre-formulated to contain all the vitamins and minerals needed for a complete and balanced diet.

Extruded feeds are ground feeds that are forced through a die under pressure and steam heat. The final product is a feed that has the consistency of dry dog food. The extruded horse feed is less dense than a pellet, and may weigh as little as one half the weight of the same volume of pellets.

 

23. State two nutrient deficiency symptoms  observed in laboratory animals

• Reduced appetite in young animals.
• Lowered feed intake.
• Lack of muscle development.
• A prolonged time to reach maturity.
• In mature animals there is loss of weight and decreased milk production.

24. Describe the breeding process of rabbits

• Rabbits of preferred genetic characteristics are selected and allowed to mate
• The female rabbit (doe) does not come into heat (oestrus) as do other animals. The doe will accept the male (buck) at any time of the year.
• Does are mature and can breed at 5 to 6 months of age and can continue to have young for 4 years.
• The length of pregnancy in the rabbit is 31 days and the doe can produce from 1 to 12 young each time she gives birth. She can become pregnant again within a few days of giving birth. However it is not good practice to allow the doe to become pregnant straight after giving birth. It is better to mate the doe when her young (litter) are 4 weeks old so that they are 8 weeks old when the next litter is born. In this way one doe can produce 6 litters a year.
• Two weeks after mating you can feel the young through the side of the doe’s belly.

 

25. State five differences between rats and mice

Rats and mice are both rodents, so look similar – the biggest difference is their size.

Rats are larger and heavier while mice have smaller slender bodies. Mice also have long slender tails (for their body size) covered in hair compared to rat tails which are shorter, thicker and hairless.

26. Describe the daily feeding of a laboratory rabbit

All laboratory animals including  rabbits  should receive food that is

1. Palatable
2. Free from contamination and
3. Balanced and of sufficient quantity and nutritive value to maintain their good health

They should be fed at least once on daily basis except under justified circumstances e.g. on veterinary treatment or pre-procedural fast. Specific diets should be selected based on the needs of each species. They should also be provided with clean drinking water   regardless of the type of food supplied .

Food should be provided in receptacles that are accessible to all animals in a cage or pen and placed to minimize contamination. Food receptacles should be easily cleaned and sanitized

27. State the advantages and disadvantages of using stainless steel in the construction of laboratory animal cage

• Stainless steel has superior corrosion resistance compared to other materials. Therefore, stainless steel is perfectly suited to variety of environments.
• Stainless steel is more durable and easier to maintain .
• It is also easy to clean
• Very beautiful and appealing
• However,stainless steel tend to be more expensive than other materials, such as aluminum.Furthermore it gets hot and also cools down very fast making the cages not comfortable during  extreme temperatures

28. Identify the condition that favour the transmission of infectios diseases in laboratory animals

• Poor hygienic standards
• Poor nutrion
• Presence of vectors  eg pest and parasites
• Lack of selection of disease resistant breeds
• Poor cage environment

 

29. Describe how guinea pig is lifted from a cage

Scuffing method

This method is commonly used for restraining guinue pigs , rats and  mouse

Restrain the mouse by grasping near the base of its tail.

Place the mouse onto a cage top to take advantage of the mouse gripping the top.

Grasp the nape of its neck with the forefinger and thumb of the other hand, gathering the loose skin from around the neck (below the head) and back.

Ensure that you gather enough skin to prevent the head from turning, while allowing the animal to breathe normally.

Place the tail between your ring and little fingers to secure and control the animal. The tail must be secured to prevent the mouse from moving and loosening the grip.

The tail can also be held against the palm of the hand.

The mouse is now ready for technical manipulation

Make sure that you feel comfortable holding the mouse in this position for some time because if you are not comfortable, there is a higher risk of failure.

Always use the alternative hand to your writing hand for restraining the mouse.

30. Explain how to restrain rats

Do not attempt to scruff rats unless you are very experienced, as rats, unlike mice, object strongly and vocally to being scuffed unless they are handled frequently

With firm yet gentle pressure, grasp the rat around the thorax with your thumb and middle finger under each of its front legs.

With your free index finger still under its leg, grasp the loose skin on the nape of its neck.

Take care not to squeeze the rat or apply too much pressure to its diaphragm, as this may result in injury and suffocation.

Extend the tail to keep the back straight, preventing the rat from turning around. The animal is now ready for technical manipulation.

If you encounter an aggressive rat, you can wear a cloth glove or place a small hand towel around your hand when restraining.

Take care when using metal chain gloves, as the rat’s claws can be caught in the links, resulting in injuries to the rat.

Other selected methods for handling lab animals

Guinea pigs rarely bite, but are very easily frightened and will vocalize and squirm to avoid restraint. The hind limbs must be supported at all times to prevent the animal from injuring its back

Rabbits are very susceptible to lumbar spinal luxation, resulting in paralysis. It is necessary to support the animal’s hindquarter at all times. Although rabbits seldom bite, they can inflict painful scratches with their hind legs. One way of lifting a rabbit is by grasping the skin over the shoulder with one hand and gently lifting it with the other arm cradling the body, the head nestled in the crook of your arm. Rabbits must never by lifted by the ears.

31. A cage holding six mice is to be cleaned and reused. Outline the procedure for cleaning the cage

• Remove animals from cage and temporarily  place/keep them in a clean sanitized environment
• Remove all bedding and feed and water containers from the cage.
• Remove feces and newspaper or other absorbent materials.
• Cages that are soiled should be cleaned with an alkaline cleaner like Biosolve™ Plus prior to disinfection.
• Select an appropriate cleaner and mix prior to application.
• Apply the cleaner to all surfaces until it is thoroughly wet. Apply the cleaning solution to feed and water dishes also. Allow the surfaces to soak for 10 to 20 minutes. Do not allow the cleaning solution to dry.
• Wipe with a water-soaked cloth or rinse the cleaner from all surfaces and feed and water bowls with water. Allow to dry.
• Mix and apply a disinfectant solution using a low pressure sprayer. Surfaces should remain wet with disinfectant for a minimum of 10 minutes and then be allowed to dry.
• .Dust the animals to kill fleas , bedbugs etc
• .Return the animals back to the cages

 

State the qualities for a good nesting material for laboratory animals

Nesting materials are part of a laboratory animal’s environment, and thus must meet certain criteria. It must not contain nutrients or be treated with deodorizers, disinfectants, or other chemicals, as these could affect the animals and ultimately the research.

Changing to a different bedding material in the middle of an experiment could also affect the experiment’s results. Bedding must not create levels of dust that irritate the animal’s lungs and eyes; additionally, contact bedding must be free of sharp, splintery edges or other defects that could injure animals and make nest-building difficult

There is no ideal bedding material for all species in all applications.  Wood shavings, compressed paper and straw (for large animals) are the most common types of bedding.

The bedding materials should be providing maximum comfort to the animals, easy to clean and sterilize and should not be contaminated with   pathogens, parasites e.g. mites and flees or with animal droppings. Bedding provides the nesting materials for the animals especially pregnant animals and prevents the animals from developing sores on their feet’s.

Mice use bedding to deposit odor patterns. They claim territory through urinary scent marking. Proteins specific to individuals prepare a male mouse to identify his own and another male’s urine scent. However, too much urine in crowded conditions can unnaturally extend estrous cycles.  Change the bedding about once a week.

33. Name four routes of exposure to infection in the laboratory

There are four  primary routes of entry into the body:.

Inhalation: For most chemicals in the form of vapors, gases, mists, or particulates, inhalation is the major route of entry. Once inhaled, chemicals are either exhaled or deposited in the respiratory tract. If deposited, damage can occur through direct contact with tissue or the chemical may diffuse into the blood through the lung-blood interface.

Upon contact with tissue in the upper respiratory tract or lungs, chemicals may cause health effects ranging from simple irritation to severe tissue destruction. Substances absorbed into the blood are circulated and distributed to organs that have an affinity for that particular chemical. Health effects can then occur in the organs, which are sensitive to the toxicant.

Skin (or eye) absorption: Skin (dermal) contact can cause effects that are relatively innocuous such as redness or mild dermatitis; more severe effects include destruction of skin tissue or other debilitating conditions. Many chemicals can also cross the skin barrier and be absorbed into the blood system. Once absorbed, they may produce systemic damage to internal organs. The eyes are particularly sensitive to chemicals. Even a short exposure can cause severe effects to the eyes or the substance can be absorbed through the eyes and be transported to other parts of the body causing harmful effects.

Ingestion: Chemicals that inadvertently get into the mouth and are swallowed do not generally harm the gastrointestinal tract itself unless they are irritating or corrosive. Chemicals that are insoluble in the fluids of the gastrointestinal tract (stomach, small, and large intestines) are generally excreted. Others that are soluble are absorbed through the lining of the gastrointestinal tract. They are then transported by the blood to internal organs where they can cause damage.

Injection: Substances may enter the body if the skin is penetrated or punctured by contaminated objects. Effects can then occur as the substance is circulated in the blood and deposited in the target organs

34. Outline the procedure for collecting blood from rabbit  artery

• Place the rabbit in a rabbit restrainer. Using clippers, remove the hair from the ear. A 1 to 1-1/2-inch needle ranging in size from 22-gauge to 20-gauge is recommended for blood collection.
• Extend the ear away from the rabbit’s head to provide a flat surface and insert the needle into the artery.
• Once blood begins to flow, lower the ear and position the receptacle under the needle for blood collection.
• Occasionally, the artery may constrict during the collection process, shutting off the flow of blood.
• Hold the needle securely in place until the rabbit relaxes, usually within one minute.
• Gentle massage of the artery at the base of the ear may enhance blood flow. Clot formation in the needle can also prevent blood flow.
• If no blood flows, remove the needle and repeat the procedure using a new needle.
• Insert the new needle into the artery proximal to the previous site (closer to the base of the ear).

35. Common blood Collection Sites

Collection Site	Advantages	Disadvantages
Lateral Tail Vein	Anesthesia not required Vein is easily accessed Allows for repeat collection	Must be securely restrained Yields only small quantities Requires some specialized equipment
Jugular Vein	Medium to large volumes of blood can be collected Results in a high-quality sample	Does not lend to repeated samples Anesthesia required Training:
Lateral Saphenous Vein	Anesthesia not required Repeated sampling is possible Moderate volume of blood can be collected	Requires specialized training Requires specialized equipment Variable sample quality/quantity
Cardiac Puncture	Maximum volume of blood can be collected Requires deep anesthesia	Non-survival procedure only

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

36. State the aim of  dissecting  an animal in a laboratory

Dissection is also important because it:

• Helps students learn about the internal structures of animals.
• Helps students learn how the tissues and organs are interrelated.
• Gives students an appreciation of the complexity of organisms in a hands-on learning environment.
• Provides one of the most memorable and instructive units in a school biology course.

37. Describe the various types of dosing and injection procedures which may be carried out in a rabbit

Many research programmers require the administration of substances to laboratory species. The effect of this on the animals concerned may be minimal or profound, depending on the substance itself, the formulation, the volume, the frequency of dosing and the skill of the operator. Practical expertise in a particular method should be gained by guidance from an experienced person and carried out under supervision until competence is attained. A good skill level then needs to be maintained by regular use of the method

Every effort should be made to find out as much as possible about likely toxicity and to choose a dose which will avoid unnecessary toxic effects.

Solubility problems are not uncommon. Therefore information and advice should be sought in order to ensure that formulations are effective, of minimal toxicity and compatible with the route of administration required.

38. Describe sites for substance administration in lab animals

Recommended sites and methods in rats, guinea pigs and rabbits are outlined in the table below. General recommendations include:

Firm but sympathetic restraint is essential for all methods.

Always use the smallest needle diameter which will allow reasonably swift injection of the substance.  Make certain the needle is only long enough to reach  the intended site of injection.

Always use the smallest possible volume compatible with the solubility of the substance.

Use aseptic technique for injections wherever possible.

Always observe the animals carefully after dosing for any adverse effects.

Common sites for dosing

	Mouse	Rat	Guinea-pig	Rabbit
Oral	Gavage, or in food or water	Gavage, or in food or water	Gavage, or in food or water	Drench (small volumes) or gavage
Subcutaneous	Scruff or flank	Scruff or flank	Scruff or flank	Scruff or flank
Intramuscular	Anterior thigh	Anterior thigh	Anterior thigh	Anterior thigh
Intravenous	Tail vein	Tail vein	Ear vein or saphenous vein	Ear vein

39. State any four uses of botanical garden

Botanical gardens facilitates  the study and conservation of plants, as well as making the world’s plant species diversity known to the public. These gardens also play a central role in in education, and research

40. State the significance of green house in growing plants

Greenhouses help in providing conducive an optimum environment for growth of plants besides also helping to prevent problems such as pests as well as provide more control against other diseases.

The enclosed space can be restricted to only the essential staff, and fewer people going in and out means a lesser risk of bringing unwanted elements close to the crops.

41. Name any three types of growing media in a green house

Various types of growing media used in protected cultivation include peat moss, vermiculite, perlite, shredded coconut husks (coco peat), or composted materials plus starter nutrients and a wetting agent.

42. State any four cultural ways of  controling plant  diseases and pest in a botanical garden

• Ensuring high level of sanitation,
• Removing diseased plants or plant parts,
• Rotating crops,
• Eliminating weeds or other plants that may be alternate hosts for the disease,
• Discouraging or preventing insect vectors.

43. State three advantages and  three disadvantages of overhead mist watering system in a green house

Advantages

• Misting systems carry the benefit of fending off plant diseases, minimizing plant stress and increasing growth rates. They also help establish the ideal greenhouse environment, keeping it cool, moist, humid and consistent at all times

Disadvantages

• Higher potential for evaporation and wind drift issues compared to drip.
• Waters both crops and weeds.
• Cannot be used on crops susceptible to foliar diseases.
• Higher potential for runoff and erosion compared to drip.

44. (a) Define the term mulching as used in botanical garden

In nature mulch comes from fallen leaves, plant debris and passing animals, and when we mulch in the garden we aim to recreate that cycle. However, the term mulch can be used to describe any material a gardener chooses to cover the soil with, such as compost, rotted manure, cardboard or even seaweed.

• List two materials used in mulching

 Dry leaves , compost, rotted manure, cardboard or even seaweed

45. State two advantages and two disadvantages of gutter connected greenhouse over stand alone green house

 Gutter-connected greenhouses have less roof and wall area relative to floor area, so they are more energy-efficient. There are some disadvantages, however, including reduced light due to shadow from eaves and other structural elements, and snow accumulation over the eaves