Health and Disease LAT Chapter 9 LAT Presentations Study

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Health and Disease

• LAT Chapter 9

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Disease Terminology

• Infectious Disease caused by living agents that
  invade the bodies of animals, often causing them
  to become ill
• Infected animals are called hosts. Dealing with
  microscopic organisms difficult, detected only
  after signs of disease develop.
• Contagious Diseases transmitted directly or
  indirectly, from an infected animal to a healthy
  one
• Most infectious diseases are contagious.
• Direct contact infected animals must touch one
  another.
• Indirectly airborne or aerosol transmission
• Horizontal transmission within the same
  generation
• Vertical transmission 1 generation to next
  mother to offspring

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Fomites / Vectors / Carriers

• F - Inanimate objects that provide a mechanical
  means of infectious disease transmission.
• Cages, bedding, feeding pans, scrub brushes,
  boots, clothing, gloves and dust particles
• V - Living organisms that transmit disease.
• Insects such as fleas or ticks, animal
  technicians carrying diseases from room to room
• C - Animals that can transmit infectious diseases
  to other animals without ever showing signs that
  they, themselves, have the disease.
• Hamsters, for example, show no signs of the viral
  disease lymphocytic choriomeningitis (LCM) when
  they carry the disease. People who handle
  hamsters infected with this virus can become ill
  with the disease. Mice exposed to such hamsters
  frequently develop serious clinical disease.
• Graphic from http//caplter.asu.edu/explorers/pro
  tocol/arthropods/background.htm

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Zoonosis

• Disease transmitted from humans
• to animals / animals to humans
• zoonosis, or zoonotic disease.
• tuberculosis nonhuman primates
• turtles salmonellosis.
• cats and dogs ringworm
• rabies, herpes B, lymphocytic choriomeningitis
  (LCM), toxoplasmosis, herpes simplex virus
• Table 9.1 - casual contact zoonoses
• Table 9.2 - active contact zoonoses
• Epizootic a sudden disease outbreak that affects
  a large number of animals (an epidemic in humans)
• Enzootic disease occurs in several members of a
  population or colony (endemic in humans)

For more information http//medicine.bu.edu/dshap
iro/zoo1.htm
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Noninfectious Disease

• Nutritional Diseases dominant animal may prevent
  subordinate from access to food
• skin conditions, changes in hair coat, growth
  changes, malformation of bones, and reduced
  reproductive capacity.
• Hereditary Abnormalities passed from parent to
  offspring by way of genes
• Certain ones intentionally maintained in inbred
  animals.
• Technicians who work with strain that has
  inherited problems should learn about the
  characteristic unusual responses.
• Congenital Diseases animal is born with disease
• Degenerative Diseases diseases associated with
  aging

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Noninfectious Disease
Genetic Abnormalities Discovered in Mice
From Biology of the Laboratory Mouse, by The
Jackson Laboratory,(Dover Publications, 1968),
pp.100-101
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Cancer

• Unregulated, disorganized proliferation
• Neoplasm new growth
• Chronic irritation, radiation, and certain
  chemical agents, drugs, and viruses can induce
  tumor formation.
• Several genes linked to breast and colon tumors.
• Tumors may either be malignant or benign.
• Benign tumors are not extensively invasive.
• Malignant tumors, on the other hand, often spread
  rapidly, are very invasive, even to other areas
  of the body (metastasis) and are more
  life-threatening.
• Many strains of rodents have a predisposition to
  develop specific types, which makes them useful
  animal models.

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Diagnosing Disease

• Diagnosis
• Diagnosis is usually based on clinical signs and
  symptoms, laboratory test results, and findings
  from a complete necropsy.
• A prognosis is a prediction of the probable
  course of a disease and the chances of recovery.
• Morbidity and Mortality
• The morbidity rate is the number of sick animals
  expressed as .
• Mortality refers to the number of animals that
  die from a disease.
• Sick animals that seem near death are said to be
  moribund.
• Determining Severity
• Visible disease signs overt or clinical
• No clinical signs infection is said to be
  subclinical.
• Severity depends on of host cells involved,
  extent of damage and importance of the structures.

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Classifying Disease

• Etiology - refers to their cause or origin
• Anatomically - body system where symptoms occur
• Acute - rapid onset and brief duration
• Chronic - gradual onset and long duration
• Peracute - sudden onset and violent
• Local - confined to a small area
• Systemic - affect a large part of the body
• Agents carried through the body by bloodstream
• Bacterium bacteremia / virus viremia
• Septicemia is term for proliferation of infection
  in blood.
• Lesion local area of damage.
• Gross lesions can be seen with the naked eye.
• Microscopic lesions can be seen under the
  microscope.

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Body Defenses

• Signs of inflammation are
• 1. Heat
• 2. Redness
• 3. Swelling
• 4. Pain
• 5. Loss of function
• Certain foreign organisms are not easily
  destroyed by a local inflammatory response.
• Large numbers of dead cells, bacteria, and
  phagocytes may accumulate, resulting in the
  production of pus (e.g. abscess).
• Relatively long period of inflammation is
  required for all the bacteria to be killed and
  for an abscess to heal.

For more information go to http//www.atherogen
ics.com/science/therapeutic.html
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Invading Organisms

• If organisms escape from a local area, they
  spread throughout body causing septicemia.
• Simultaneous exposure of many organs to bacterial
  infection, toxins, or waste products gt death.
• Lymphatic system drains excess fluids and debris
  from tissues.
• The lymph nodes trap many bacteria, viruses, and
  damaged cells.
• Swollen lymph nodes are a clinical sign of
  disease.
• After antigen exposure, immune system produces
  lymphocytes and antibodies against specific
  foreign substance that initially stimulated their
  production.
• Acquired (developed), active immunity to that
  substance
• Antigen-specific antibodies can be identified in
  diagnostic tests.
• Controlled exposure to antigens is the principle
  behind vaccination against bacterial, viral and
  allergic diseases.

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Allergy or Hypersensitivity

• Instead of helping, allergic immune response
  causes additional tissue damage.
• One reaction is called anaphylactic shock.
• Some organisms are adapted to surviving in an
  animal host despite the immune response.
• Parasites, such as intestinal roundworms, are a
  classic example.
• Newborns have temporary level of passive
  immunity.
• Antibodies acquired through mothers milk or
  across the placenta.
• Passively transferred antibodies protect for the
  first few weeks of life until old enough to
  produce own antibodies.
• Only infection or vaccination can stimulate a
  long-lasting active immune response.

For more information http//news.bbc.co.uk/hi/eng
lish/health/medical_notes/a-b/newsid_372000/372558
.stm
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Summary

• Unvaccinated, disease-free animals have no
  immunity from prior exposure.
• As health status of laboratory animals improves,
  quality of care and observation provided by
  laboratory animal technicians must also improve.
• Hosts immune system usually recognizes a
  disease agent as foreign and mounts some type of
  defense.
• Host may be successful or unsuccessful in
  fighting off disease.
• depending on of organisms or concentration of
  agent to which it was exposed, the nature of the
  agent, and way host reacts
• If successful, host lives after recovering if
  unsuccessful, it may die. If the host lives, it
  may or may not develop immunity.

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Preventing Curing Disease

• Preventive medicine way to avoid disease.
• Requires barriers between hosts and organisms or
  immunization before infection occurs.
• Antibiotics or anti-inflammatory drugs, often
  required to help combat disease.
• Many diseases are no longer common problems in
  rodents born and raised in barriers.
• Wild rodents and cockroaches occasionally get in.
• Imported primates and other wild animals, often
  contain exotic disease organisms.
• Be on alert for outbreaks and zoonotic health
  problems.
• Cleanliness and sanitation are still backbone of
  disease prevention and control.

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Prevention Control of Disease

• 1. Quarantine
• 2. Sanitation and hygiene
• 3. Periodic examination
• 4. Appropriate immunizations
• 5. Proper waste disposal
• 6. Upkeep of physical facilities
• 7. Isolation procedures

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Identifying Treating Diseases

• Physical Exam - In most cases, exam is a quick
  visual check to be sure the animal is eating,
  drinking and behaving in a normal manner.
• Cage should be observed for signs of blood,
  abnormal feces or excessively wet or dirty
  bedding.
• Physical examination is the single-most
  important step in evaluating the health of an
  animal.
• Observe closely, before attempting to restrain
  animal, so that its movement and breathing can be
  assessed prior to the excitement of restraint.
• TPR - body temperature, pulse rate and
  respiration rate
• Physical exam includes close inspection of eyes,
  ears, mouth, nose, hair coat, legs, feet and tail
  for evidence of clinical signs.

Image from NIH Orientation
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Abscesses

• Swellings filled with purulent material (pus) are
  a mixture of dead bacteria, liquefied tissue, and
  white blood cells.
• Most common just under skin, at site of puncture
  wounds.
• Bacteria are deposited under skin and the skin
  closes over them.
• White blood cells to fight the infection.
• White blood cells release substances that digest
  and liquefy some of the tissue, the bacteria, and
  themselves.
• Treatment usually consists of surgically opening
  abscess to drain purulent material.
• Abscess cavity is flushed and antibiotics are
  administered until the wound heals.
• Early treatment helps prevent spread of organisms.

For more information http//www.marvistavet.com/h
tml/body_bite_wound_abscess.html
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Alopecia

• Loss of hair
• Reasons - excessive grooming, metabolic
  dysfunction, external parasites, and nutritional
  disorders
• Pattern of hair loss is important in determining
  the cause.
• In rodents, a dominant animal often chews hair
  off the head, neck, and back of cagemates, a
  behavior called barbering.
• Fungal ringworm infections cause hair loss in
  circular pattern.
• Areas of alopecia on both sides of the body are
  common in several metabolic diseases.
• External parasites, such as fleas, mites, or lice
  and nutritional deficiencies of some vitamins and
  minerals common cause gt skin surface is not
  normal.
• Overall thinning from hair shed in spring and
  fall.

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External Parasites/Conjunctivitis

• Infestations with fleas, lice, and mites often
  result in alopecia caused by scratching.
• Seen around the neck, between rear legs, and on
  back, cranial to tail. Mites - microscope is
  required.
• Ear mites, most common in dogs, cats, rabbits,
  ferrets.
• Can trigger bacterial infections in the outer
  ear.
• Insecticide treatment gtpossible toxicity.
• Multiple treatments destroy newly hatching
  parasites.
• Conjunctivitis is a redness or inflammation of
  tissue around eyes.
• Cause - air irritants, infections, or allergies.
• Viruses and bacteria can also cause
  conjunctivitis.
• If only one eye is involved, the cause may be an
  injury.

Forms in the Fleas Lifecycle
For more information http//www.cornellcollege.e
du/biology/insects/mattmeriah/f.htm
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Mastitis / Hoof or Nail

• Mastitis infection of the mammary glands
• Occurs during early nursing period or just after
  weaning.
• Swollen, firm and hot, and may even turn blue or
  black
• Treatment take young away and administer
  antibiotics.
• A foster mother or bottle feeding may be
  necessary if the young cannot eat solid food.
• Overgrown Hoof or Nail Diseases from poor
  husbandry
• Common in sheep, goats, rabbits, cats and dogs.
• Birds develop overgrown nails and beaks.
• Treatment clipping the claws or trimming hooves.
• Animals on concrete floors seldom have this
  problem.

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Disease of Internal Organs
Salmonella

• Enteritis intestinal inflammation gt diarrhea
• Enteritis can be caused by bacteria, viruses,
  endoparasites, spoiled food, or
  contaminated water.
• Salmonella, canine parvovirus, feline
  panleukopenia, MHV, roundworms, tapeworms,
  hookworms, and coccidia
• Spoiled food and contaminated water from the
  direct action of bacteria, mold, fungi or their
  chemical toxins.
• Pneumonia infection of the lungs
• Caused by a variety of bacteria, viruses, or
  other organisms.
• Signs shallow, labored breathing, coughing,
  general weakness.
• Antibiotics are used to treat, not effective
  against viruses.
• Good nursing care important aspect of treatment,
  and effective quarantine and isolation programs
  help control the spread.

Graphic from http//www.bioan.dk/Projekter/salmon
ella.htm
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Behavioral Disorders

• Trauma usually results from some inappropriate
  behavior.
• Social hierarchies gt dominant and submissive.
• Minor fights usually occur when animals are first
  put together.
• Once social hierarchy is established, fighting
  usually subsides.
• NH primates may fight to near death to establish
  dominance.
• Self-mutilation behavioral disease results in
  trauma
• Seen mostly in NH primates, but can occur in any
  species.
• Self-mutilation can result from frustration and
  boredom.
• Large male monkeys may mutilate themselves if
  placed in direct eye contact with one another.
• Enrichments such as hard nylon balls, food
  puzzles, swing chains, tiered perches, polished
  metal mirrors.
• Soft background noise used to reduce stress and
  aggression.

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Behavioral Disorders (continued)

• May be caused by behavior of people.
• Ensure cages are well kept, designed and
  maintained.
• Sharp edges or protruding wires result in cuts or
  injures.
• Improper handling also causes disease problems.
• Rabbits lifted improperly can easily sustain
  broken backs while kicking in an attempt to find
  firm footing.
• Rats or gerbils can have the skin stripped from
  the tail if lifted improperly by the tip of the
  tail.
• These types of animal injuries are best prevented
  by assuming a responsible, humane attitude and
  nourishing it with a good education in the
  proper restraint, handling, and care of animals.

Image from NIH Orientation
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Additional Reading

• 1. Bhatt, P.N., Jacoby, R.O., and New, A.E. Viral
  and Mycoplasmal Infections of Laboratory Rodents.
  Academic Press, Orlando, FL, 1986.
• 2. Fox, J.G., Cohen, B.J., and Loew, F.M.
  Laboratory Animal Medicine. Academic Press,
  Orlando, FL, 1984.
• 3. Harkness, J.E. and Wagner, J.E. The Biology
  and Medicine of Rabbits and Rodents, 4th. Ed. Lea
  and Febiger, Philadelphia, Pennsylvania 1995.
• 4. Hrapkiewicz, K., Holmes, D.D. Clinical
  Laboratory Animal Medicine. Iowa State University
  Press, Ames, IA, 1997.
• 5. Outteridge, P.M. Veterinary Immunology.
  Academic Press, Orlando, FL, 1986.
• 6. Siegmund, O.H. et al., eds. The Merck
  Veterinary Manual, 7th Ed. Merck and Co., Inc.,
  Rahway, NJ, 1991.
• 7. Hillyer, E.V. and Quesenberry, K.E. Ferrets,
  Rabbits and Rodents Clinical Medicine and
  Surgery, W.B. Saunders, Philadelphia, PA, 1997.
• 8. Manning, P.J., Ringler, D.H. Newcomer, C.E.
  The Biology of the Laboratory Rabbit, 2nd.
  Edition, Academic Press, San Diego, CA, 1994.