Health and Disease

1. Health and Disease LAT Chapter 9

2. LAT Presentations Study Tips • If viewing this in PowerPoint, use the icon to run the show. • Mac users go to “Slide Show > View Show” in menu bar • Click on the Audio icon: when it appears on the left of the slide to hear the narration. • From “File > Print” in the menu bar, choose “notes pages”, “slides 3 per page” or “outline view” for taking notes as you listen and watch the presentation. • Start your own notebook with a 3 ring binder, for later study!

3. 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

4. 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/protocol/arthropods/background.htm

5. 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/dshapiro/zoo1.htm

6. 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

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

8. 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.

9. 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.

10. 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.

11. 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.atherogenics.com/science/therapeutic.html

12. 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 => 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.

13. 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/english/health/medical_notes/a-b/newsid_372000/372558.stm

14. 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. • Host’s 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.

15. 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.

16. 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

17. 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

18. 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/html/body_bite_wound_abscess.html

19. 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 => skin surface is not normal. • Overall thinning from hair shed in spring and fall.

20. 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 =>possible 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 Flea’s Lifecycle For more information: http://www.cornellcollege.edu/biology/insects/mattmeriah/f.htm

21. 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.

22. Salmonella Disease of Internal Organs Enteritis: intestinal inflammation => 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/salmonella.htm

23. Behavioral Disorders • Trauma usually results from some inappropriate behavior. • Social hierarchies => 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.

24. 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

25. 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.