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Chapter 7 Animal disease and parasites.

Chapter Objectives

* Define disease

* Understand the basics of disease transfer

* Understand how to prevent disease

* Identify diseases in animal species

* Learn the diseases that pose a risk to human health

* Learn the parasites that affect animals and how to control them

Disease (dih-zez) is a term that broadly describes any difference from the normal health of a living thing. Diseases can include metabolic diseases, such as ketosis (ke-to-sihs), injuries such as broken bones and cuts, or diseases caused by other organisms, such as bacteria, viruses, and parasites. Some diseases are also genetic, and are inherited from the parents.

Infectious diseases are caused by pathogens that multiply in the body and cause damage to the body. When the number of pathogens in a body reaches a high concentration, disease can be passed on to others. Diseases can be passed from one animal to another in a variety of ways. Some diseases are passed on by vectors, another living being that carries the disease from one animal to another. Mosquitoes and ticks are two insects that serve as vectors. Disease can also be passed directly from animal to animal through blood, saliva, or other secretions. Some diseases are transmitted by coughing and sneezing, when the pathogen is carried on droplets of moisture through the air. Other pathogens can live in the soil or on surfaces for extended periods of time, and be passed to animals that come in contact with those surfaces.

Although most diseases affect a specific species, some diseases can be passed from animals of one species to animals of another. Diseases that can be passed from animals to humans are zoonotic (zoo-oh-naht-ik) diseases, and are of special concern to animal health and public health officials.

The study of diseases is etiology (e-te-ohl-o-je). Etiologists study the causes and transmission of, and the cures and preventions for diseases. Symptoms of disease are the characteristics that affected animals show and that make a person believe the animal has a disease. Some diseases have similar symptoms, which makes them difficult to identify or diagnose.


Disease prevention and treatment are important parts of animal ownership and management. The following are some basic steps to prevent and treat disease:

Antibiotic (ahn-tih-bi-oh-tihck) A chemical given to an animal to battle disease organisms. Antibiotics are very specific to the disease organism in question. If an animal is being raised for consumption, it is important to be aware of the antibiotic withdrawal time, the time that must pass between the treatment and sale of the animal. Observing antibiotic withdrawal time ensures that antibiotics used in animals are not introduced into the food supply.

Antibody (ahn-tih-boh-de) An antibody is produced by an animal's immune system to fight off disease-causing organisms. Specific antibodies are produced to battle specific disease-causing organisms.

Antigen (ahn-tih-jehn) Something that the body believes is foreign, and that stimulates a response from the immune system. Bacteria and viruses are types of antigens.

Biosecurity A plan or process to prevent disease organisms from entering a facility or a country.

Core vaccine A vaccine recommended for all animals.

Recommended vaccine A vaccine recommended for animals fitting a set of guidelines that indicate they are at risk for the disease.

Resistance This occurs when a disease-causing organism or parasite develops an ability to withstand chemicals designed to protect animals. Resistance can develop either to antibodies, or to the chemicals used to fight parasites.

Sanitation The practice of keeping a facility clean and free of contaminants. Sanitation is a crucial step to reducing disease in a herd or flock of animals.

Titer (ti-ter) The measure of antibodies in the blood of an animal. Measuring the titer is one way to determine whether an animal has sufficient defense against an organism.

Vaccination (vahck-sihn-a-shuhn) The introduction of a form of a disease-causing organism to an animal to stimulate the body to produce antibodies to fight the organism. Vaccines can be modified live, which means that the disease-causing organism has been changed to make it less dangerous, or killed, in which case the disease-causing organism is dead and cannot reproduce. Some vaccines come in both forms. Also available are some recombinant vaccines, which are genetically modified to stimulate a response from the immune system without causing disease. A veterinarian should be involved in developing a vaccination program for animals.


Infectious diseases (ihn-fehck-shuhs dih-zez) are those that are caused by pathogens (pahth-o-jehnz), which are microorganisms. Pathogens are often bacteria and viruses, although other organisms can cause disease, and are most often species-specific. For example, multiple species, including humans, can get influenza; however, the disease-causing pathogen for each species is species-specific. The pathogens causing most common diseases are endemic (ehn-dehm-ihck) in the environment, meaning they are always around.

Different things can result in an animal contracting a disease. Animals that are under stress are more likely to contract a disease than those that are not. Stress results in a decrease of an animal's ability to resist disease. Poor nutrition, or a lack of needed nutrients, can cause stress that weakens an animal's immune (ihm-yoon) system. The immune system is a body's defense system against infection. Diseases can be either chronic (krohn-ihk), which means they are of moderate intensity, last for a long time, and may come and go; or can be acute (ah-kut), which means they are very intense and relatively short in duration. Some diseases can begin as an acute disease, and then become a chronic disease.

Noninfectious diseases are those that are caused by something other than a pathogen, and are not passed from one animal to another. Noninfectious diseases include nutritional diseases, genetic diseases, and allergies. In some diseases, multiple factors, such as genetics and nutrition, can contribute to the expression of the disease.


Following is a list of common infectious diseases, all caused by some type of pathogen:

Abscesses Abscesses are an infection that the body contains in a pocket. These are often caused by bacteria. In cats, abscesses are usually associated with injuries resulting from fighting, and are often seen in male cats that are frequently outdoors. Draining abscesses and treating with antibiotics is effective. Species affected: all species

Anthrax (ahn-thracks) Anthrax is caused by bacteria that live in the soil, and can live in a dormant state for many years. Animals are infected by consuming the bacteria when grazing, or by infection from another animal through a vector, such as a biting insect. Symptoms include fever, ataxia (a-tacks-eah)--the loss of muscular control--difficulty breathing, and eventually collapse (see Figure 7-1). An effective vaccine can be used to control anthrax in areas of concern. Species affected: bovine, equine

Arthritis An inflammation of the joints that can be caused by either bacteria or a virus. Arthritis results in swollen joints and lameness. Affected birds may lose weight and may have diarrhea. Some bacterial forms of arthritis are treatable with antibiotics, but the viral form is not. Species affected: avian


Aspergillosis (ahs-per-jeh-lo-sihs) A type of pneumonia caused by a fungus or a mold. Aspergillosis can affect birds of any age, and has a high mortality rate in young birds. Symptoms include loss of appetite and loss of weight. Eliminating exposure to the fungus or mold is the best preventative; there is no effective treatment. Species affected: avian

Atrophic rhinitis (a-tro-fik ri-ni-this) Two different bacteria, Pasteurella or Bordetella, can infect the nasal passages and cause atrophic rhinitis. Symptoms include sneezing, tearing, and nasal discharge. As the bones atrophy, the snout becomes twisted. Species affected: porcine

Avian erysipelas (air-ih-sip-eh-lehs) An infection caused by bacteria that most commonly affects turkeys. Birds on the flock often begin dying before other symptoms of diarrhea and anorexia are noticed. Treatment with antibiotics may be effective, and birds can be vaccinated if erysipelas is present in the region. Species affected: avian

Avian influenza Caused by a virus, avian influenza can affect birds, causing coughing, sneezing, and weight loss. Avian influenza is being closely monitored due to concerns that a mutation of the virus may create a human health hazard. Species affected: avian

Avian leukosis (loo-ko-sihs) Marek's disease and lymphoid leukosis are two forms of avian leukosis, and are caused by different viruses. Marek's disease affects the nerves and results in paralysis and death; lymphoid leukosis affects the bones. There is no treatment for either form of the disease, but a vaccine does exist for Marek's disease. Species affected: avian

Blackleg A disease caused by anaerobic bacteria. Anaerobic bacteria are those that do not require oxygen to survive. The bacteria that causes blackleg live in the soil and enter an animal's body either by mouth, or by entering through a wound. The bacteria infect the wound and cause lameness, depression, and fever (see Figure 7-2). Blackleg can be treated with antibiotics if it is diagnosed early. An effective vaccine does exist for blackleg. Species affected: bovine

Bluecomb This term refers to two different diseases. The turkey form is caused by a virus and results in diarrhea and dehydration. Although birds of all ages can be affected, bluecomb is most fatal for young birds. Bluecomb in chickens is caused by a different organism than that in turkeys, but is probably still a virus. Birds become anorexic, decrease production, and lose weight. The comb may also become bluish in color. Antibiotics can be used to treat bluecomb in turkeys and chickens. Sanitation is important in preventing both forms of bluecomb. Species affected: avian


Bluetongue Caused by a virus and spread by gnats, blue tongue results in loss of appetite, and swelling around the head and mouth. Vaccination is an effective preventative. Treatment consists of treating the symptoms. Affected species: caprine, ovine

Bordetellosis (bor-deh-tah-lo-sihs) Also known as kennel cough, bordetellosis is a bacterial upper respiratory infection that affects dogs and cats. A vaccine is effective, and is highly recommended for animals that are exposed to a large number of other animals, such as through showing or boarding. Species affected: canine, feline

Bovine respiratory syncytial virus (sihn-sihsh-uhl) A bacterial disease that affects the respiratory system, primarily in young calves. Stress increases the likelihood of this disease. An effective vaccine does exist. Species affected: bovine

Bovine spongiform encephalopathy (BSE) (spuhn-ghi-form en-sef-ah-lop-ah-the) Also known as "mad cow disease," BSE affects the central nervous system of cattle and other ruminants. A federal surveillance plan is in place in the United States to detect any signs of BSE in the U.S. cattle population. BSE is believed to be transmitted through consumption of feed that contains prions. Prions are only present in the central nervous tissue in an infected animal, so the risk of transmission to humans is extremely low. Symptoms of BSE include nervousness, weight loss, and aggression. There is no vaccine or effective treatment for BSE. Species affected: bovine

Bovine viral diarrhea (BVD) A disease that affects cattle of all ages. The symptoms include fever, coughing, slow weight gain, and diarrhea. An affected pregnant cow may abort the fetus, or deliver a mummified fetus, depending on the stage of pregnancy during which the cow became infected. An effective vaccine does exist for BVD. Species affected: bovine

Brucellosis (broo-sehl-oh-sihs) A serious disease in cattle that is caused by a microorganism that also causes undulant fever in humans. Brucellosis can result in sterility in cows or bulls, late-term abortion, and delivery of weak calves. Brucellosis can be spread through direct contact with an infected animal, an infected fetus, or with feed or water that has been infected. There is no cure for brucellosis, but effective vaccination and screening programs have greatly reduced the incidence. Because of the disease's tremendous economic impact, state and federal programs assist in the elimination of brucellosis in cattle. Species affected: bovine, canine, porcine

Calf enteritis (scours) Scours is a broad term for calf diarrhea. The causative organism will vary depending on the part of the country. E. coli is one of the common bacteria that causes scours. Scours most often affects young calves. In acute cases, calves may have cold extremities (ears, nose, legs) and diarrhea, and may die quickly after symptoms are noticed. In chronic cases, calves have diarrhea and lose weight until death occurs. Sanitation of all items that the calves had contact with will reduce the incidence of scours. It is also important that affected calves receive antibody-rich first milk, colostrom (ko-lah-struhm), from the cow. Vaccination of cows prior to calving increases the antibodies in the colostrum, and provides additional protection for calves. Species affected: bovine

Canine distemper (dis-tehm-per) Caused by a virus and transmitted through the virus in secretions of the infected animal, distemper can cause anorexia, coughing, and sneezing. In severe cases, the central nervous system is affected. Distemper can result in a high death rate in unvaccinated puppies. Vaccination is an effective preventative and is a core vaccine in dogs. Species affected: canine

Canine parvovirus (pahr-vo-vi-rhus) A highly infectious viral infection that results in diarrhea. Parvovirus can also damage the heart of affected dogs. Parvovirus is most often seen in puppies, and has a high mortality rate in unvaccinated puppies. Parvovirus is a core vaccine in dogs. Species affected: canine

Chlamydia (klah-mid-e-ah) An infection with the Chlamydia bacteria can cause conjunctivitis (infection of the eyelid), or upper respiratory infection in cats. Antibiotics are an effective treatment. Species affected: feline

Cholera (kahl-er-ah) Historically a devastating disease with a large number of hogs dying annually, cholera has been eradicated in the United States, although it still occurs in other countries. Hog cholera is caused by a virus, and characterized by loss of appetite and fever. Species affected: porcine

Clostridial diarrhea (klah-strihd-e-ahl) A bacterial infection of the intestine that causes diarrhea in pigs less than a week old. The mortality rate may be as high as 25 percent. Symptoms are watery diarrhea and lethargy. Sanitation of facilities is the best prevention, and vaccination of sows may be helpful. Treatment of infected piglets is usually unsuccessful. Species affected: porcine

Encephalomyelitis (ehn-sef-ah-lo-mi-ah-li-tihs) Also known as sleeping sickness, encephalomyelitis refers to several strains of a virus that affects the brain. All strains of encephalomyelitis are carried by mosquitoes, and are characterized by fever, depression, circling, and pressing of the head against a solid surface. Vaccination and elimination of mosquito breeding areas are effective in prevention. Species affected: equine

Enterotoxemia (ehn-tar-o-tock-sem-e-ah) Also known as overeating disease, enterotoxemia is caused by bacteria and affects goats and sheep. Vaccination of lambs and ewes, and ensuring adequate roughage in the diets of lambs will reduce the incidence. Once the symptoms have begun, treatment is not available. In cattle, enterotoxemia can result from overeating concentrated diets. Vaccination can also prevent symptoms in cattle. Species affected: bovine, caprine, and ovine

Equine infectious anemia (EIA) Also known as swamp fever, EIA is caused by a virus that biting insects such as flies and or mosquitoes carry. There is no cure, or effective treatment for EIA. Horses can be tested for EIA with the Coggins test, which detects the existence of antibodies to equine infectious anemia. Many states require documentation of a negative test for EIA for horses to be transported across state lines, or within the state. Species affected: equine

Equine protozoal myelitis (EPM) (pro-to-zo-ahl mi-eh-li-tihs) EPM is caused by protozoa that infect the central nervous system. Opossums are an intermediate host, and infection commonly occurs when feedstuffs, such as hay, are contaminated with infected fecal material. Horses with EPM show symptoms typical of neurological challenge, and may be uncoordinated. Treatment with antibiotics has shown some success, and a vaccine is available, although the effectiveness of the vaccine has not been proven as of publication of this book. Species affected: equine


Erysipelas (air-ih-sihp-eh-lehs) Caused by bacteria, erysipelas can affect pigs at any age between weaning and maturity. Animals with erysipelas have red lesions on the skin, and develop arthritis that leads to lameness (see Figure 7-3).Vaccination is an effective prevention for erysipelas. Species affected: porcine

Exudativeepidermitis (ehcks-yoo-da-tehv ehp-ih-derm- -tihs) Occurs when bacteria on the skin infect areas where the skin has been broken by bites, scratches, or other injuries. The bacteria multiply, and the animal develops red spots that ooze fluid. Eventually, the animals may become dehydrated from loss of the fluid. Antibiotics can be effective for treatment under the supervision of a veterinarian. Reducing stress and maintaining a clean environment will prevent the disease. Species affected: porcine

Feline calicivirus (kah-lek-e-vi-ruhs) A viral upper respiratory infection in cats that can be transmitted through direct contact between animals. Symptoms include sneezing, fever, and anorexia. Vaccination is effective in prevention, and treatment consists of treating the symptoms while the virus runs its course. Feline viral rhinotracheitis is a similar disease. Calicivirus and rhinotracheitis are core vaccines for cats. Species affected: feline

Feline immunodeficiency virus (FIV) (ihm-myoo-no-de-fish-ehn-ce) FIV is caused by a lentivirus that attacks the immune system of the cat. Most often, FIV is transmitted through bites from infected cats. Preventing exposure to infected animals is important. FIV is fatal, and there is no cure. Although similar to human immunodeficiency virus (HIV) in humans, FIV is species-specific, and is not transmissible to humans. Species affected: feline

Feline infectious peritonitis (FIP) (pehr-ih-to-ni-tihs) FIP is caused by a coronavirus, and symptoms include anorexia, fever, vomiting, and diarrhea. Diagnosis can be confirmed through laboratory testing. There is no effective treatment. Vaccination is available, but is not widely used. Species affected: feline

Feline leukemia virus (FeLV) (loo-kem-e-ah) FeLV is caused by a virus and can be transmitted from cat to cat through secretions such as saliva. Biting is not necessary to transfer the virus. Fever, depression, and anorexia are common symptoms. Vaccinations do exist, and high-risk cats (those that spend significant time outside, live with cats with FeLV, and so on) should be vaccinated. There is no effective cure for the disease, and animals may carry the virus and show no symptoms. Species affected: feline

Feline viral rhinotracheitis (FVR) (ri-no-trak-e-i-this) FVR is a viral upper respiratory infection in cats caused by a herpesvirus that can be transmitted through direct contact between animals. Symptoms include sneezing, fever, and anorexia. Vaccination is effective in prevention, and treatment consists of treating the symptoms while the virus runs its course. Similar to feline calicivirus. Species affected: feline

Foot and mouth disease (FMD) Foot and mouth disease is caused by a virus. Although humans can transmit the virus to animals on their clothes, and can carry the virus in their nasal passages for a few hours, FMD is not transmissible to humans, and does not pose a human health risk. Reproductive efficiency, milk production, and growth all decrease when an animal is infected with FMD. A vaccination does exist; however, vaccinated animals can spread the disease. Because of the significant economic impact of an outbreak of FMD, some countries choose to destroy infected animals to minimize the opportunity for an outbreak. Species affected: bovine, caprine, ovine, deer

Foot rot A general term used to describe an infection of the foot that can be caused by a virus, bacteria, or fungus. These pathogens enter the foot through a break in the skin, and cause an infection that results in lameness. The animal may get a fever and lose weight, especially if the lameness makes it difficult to access feed. Foot rot can be prevented by maintaining a clean environment for the animal, and can be treated with antibiotics. Species affected: bovine, caprine, ovine

Infectious bovine rhinotracheitis (IBR) A viral disease with several forms, depending on what part of the system the virus affects. Respiratory IBR affects the respiratory system and is the most common form. Genital IBR affects the genitalia of either males or females. Conjunctival IBR (kohn-juhncktivahl) affects the eye, and encephalitic IBR (ehnsehfah-lih-tik) affects the brain and nervous system. IBR may cause abortions in pregnant animals. No treatment exists for IBR; however, vaccination programs and quarantine of new animals can minimize the incidence of IBR. Species affected: bovine

Influenza A respiratory disease caused by a viral (in the case of swine flu, also a bacterial) infection. Vaccination can prevent the disease, and most animals recover, although the disease results in decreased growth. Antibiotics are not effective in treatment. Species affected: canine, equine, porcine

Johne's disease (yo-nez) Also known as paratuberculosis (pahr-ah-tuh-berk-yoo-lo-sihs), Johne's disease is a chronic disease that is characterized by diarrhea in adult animals. Diarrhea causes weight loss and decreased production in animals, and may lead to death (see Figure 7-4). There is no effective treatment for Johne's disease, and care should be taken to avoid bringing affected animals into a herd. Species affected: bovine, ovine

Mastitis (mahs-ti-tihs) An inflammation of the mammary gland. Mastitis can either be caused by a pathogen, or can be noninfectious in nature. Antibiotic treatment is effective, but recurring mastitis can cause permanent damage to the mammary gland. A gland with mastitis may be swollen, hot, and sore. If the female is nursing young, the presence of mastitis will reduce the ability of the offspring to obtain milk. Milk from dairy cows that have mastitis, or are being treated with antibiotics for mastitis, cannot be sold for human consumption (see Figure 7-5). Sanitation is vital to the prevention of mastitis. Species affected: All mammals.

Mastitis-metritis-agalactia (MMA) (a-gahl-ahck-te-ah) A complex disease of unknown cause, MMA is characterized by a sow having no milk (agalactia) when piglets are born. The mammary gland shows signs of mastitis. Reducing stress on the sow appears to minimize incidence of MMA. Species affected: porcine



Metritis (meh-tri-tihs) An infection of the uterus that can be caused by a variety of pathogens. Symptoms include depression, loss of appetite, and failure to conceive. Animals that retain the placenta after parturition are more likely to have metritis. (A retained placenta is when a placenta does not completely disengage from the uterus, and all or part of the placenta remains in the reproductive tract.) Treatment with antibiotics can be effective for metritis; however, it is important to identify the pathogen that causes the infection for effective treatment. Species affected: all mammals

Mycoplasmosis (mi-ko-plahz-mo-sihs) A group of respiratory diseases in poultry that are caused by a variety of Mycoplasma bacteria. Different bacteria cause different strains of the disease. The disease can spread rapidly through a flock and result in significant economic loss. Treatment and prevention varies with the strain of bacteria present. Species affected: avian

Mycotoxicosis (mi-ko-tocks-ih-ko-sihs) Abroad term used to describe disease caused by fungus or molds in the feed that are ingested by birds, and then produce toxins in the body. Symptoms range from anorexia to death, depending on the level and type of toxin present. The best preventative is the proper storage of feed to eliminate exposure to molds and fungus. Species affected: avian

Navel Ill A bacterial infection of the navel that occurs shortly after birth. Causes joint swelling and pain, weight loss, and potential death. Antibiotics are an effective treatment, and good sanitation practices prevent infection. Species affected: all mammals

Necrotic enteritis (neh-krah-tik) Caused by bacteria that inflames the intestinal tract and causes diarrhea and anorexia. Treating with antibiotics may be helpful, as well as separating sick and healthy pigs, and maintaining sanitary conditions. Species affected: porcine

Newcastle disease A viral disease of major concern in the poultry industry. Several viruses can cause different forms of Newcastle disease. Affected birds have difficulty breathing, appear nervous, and may show neurological signs such as tremors and paralysis. Birds in production will show a decrease in production. There is no treatment for Newcastle disease, but sanitation and vaccination can reduce the incidence. Species affected: avian

Pasteurellosis (pahs-cher-ehl-o-sihs) An infection in rabbits caused by the bacteria Pasteurella multocida. The bacterial infection can become localized in different areas, resulting in diseases with different names. Snuffles is a common form of pasteurellosis, which is concentrated in the upper respiratory tract (see Figure 7-6). Pasteurella can cause pneumonia, an infection of the lungs; pyometra (pi-o-me-trah), an infection in the uterus; orchitis (o-r-ki-tihs) an inflammation of the testicles; otitis (o-ti-tihs) media, an infection of the middle ear; conjunctivitis, an inflammation of the eye; abscesses in the skin; and septicemia (sehp-tih-se-me-ah), a blood infection. Species affected: rabbits

Pinkeye An infection of the cornea of the eye caused by bacteria. The bacteria can be carried by insects, by dust, or directly transferred from one animal to another. If pinkeye is left untreated, it can permanently damage the eye and cause blindness. Animals with white faces and pink skin around the eyes are more likely to be affected. The symptoms include pinkness and cloudiness of the eye, swelling, and tearing. Some vaccinations are available, and a veterinarian should be consulted to determine the best vaccine. Cattle can be treated with antibiotics in the eye, and by protecting the affected eye from light. Species affected: bovine, caprine, ovine


Pneumonia (nu-mo-ne-ah) An inflammation of the lungs, pneumonia has many potential causes: bacterial, viral, and parasitic. Pneumonia often accompanies another illness that has weakened the immune system and stressed the body. Antibiotics can be effective for treatment. Severe cases can cause permanent damage to the lungs, even if the animal survives. Species affected: all

Potomac horse fever (PHF) Characterized by diarrhea, fever, and depression, PHF is caused by the organism Ehrlichia risticii. The organism cannot live outside a cell, so cannot be transmitted through the environment. The precise mechanism of spread is unclear, but it appears that some type of vector, probably insects, is involved. Secondary diseases, such as laminitis, are also of great concern in horses with PHF. Treatment with antibiotics is successful, and horses in areas with a high occurrence of PHF can be vaccinated. Species affected: equine

Pseudorabies (soo-do-ra-bez A viral disease that can affect pigs of any age. The symptoms vary somewhat with the age group. In general, affected animals have fevers, vomiting, and may cease feeding. Antibiotics are not effective for treating pseudorabies. Various hog-raising regions have eradication plans in place for pseudorabies. Pigs should be purchased from certified pseudorabies-free herds. Species affected: porcine

Rhinopneumonitis (ri-no-noo-mah-ni-tihs) An upper respiratory infection caused by any of several herpesviruses. Vaccination is effective for preventing rhinopneumonitis. Rhinopneumonitis can cause late-term abortions in pregnant mares. A killed virus vaccine has been developed to protect pregnant mares from the virus. Species affected: equine

Scrapie (skra-pe) In the same family of diseases as bovine spongiform encephalopathy, scrapie attacks the central nervous system. Scrapie has an incubation period of a year, so is most often seen in older animals. Symptoms include weight loss, abnormal walking gait, and loss of coordination (see Figure 7-7). There is no cure or treatment, and the USDA has a voluntary program in place to identify scrapie-free flocks in an effort to reduce the incidence of the disease. Affected species: caprine, ovine


Shipping fever Shipping fever is a broad term for a complex disease that is caused by stress, a viral infection, and a bacterial infection. The disease complex results in respiratory symptoms, such as difficulty breathing, coughing, and nasal discharge. Animals are depressed, do not eat, and have diarrhea, which results in significant weight loss. Affected animals are susceptible to secondary infections, which result when the body is too weakened to fight them off. Vaccination and reduction of stress are the best preventatives. Treatment with antibiotics can be effective if begun early in the progression of the disease. Species affected: bovine

Sore mouth A viral infection that results in pus-filled blisters in affected areas. The lips, mouth, and udder are most affected. Blisters create discomfort when eating, so many animals lose weight or don't allow young to nurse if infected (see Figure 7-8). Vaccination can prevent sore mouth. Affected species: caprine, ovine

Strangles (distemper) In horses, strangles is caused by the bacteria Streptococcus equi. Symptoms include swelling of the lymph nodes under the jaw, nasal discharge, and lethargy. A vaccine is available, and a veterinarian should help determine if the vaccine is appropriate for a given situation. Antibiotics can help in treating the disease. Species affected: equine

Swine dysentery (dihs-ehn-ter-e) Also known as bloody scours, swine dysentery is caused by bacteria. Symptoms include anorexia and slow weight gain. The bacteria are shed in fecal material, and can be carried on unclean clothing and tools from farm to farm, or barn to barn. Antibiotic treatment can be effective, but disease prevention is a priority. Species affected: porcine

Tetanus (teht-nuhs) Also known as lockjaw because of the characteristic rigidity of the jaw in affected animals, this bacteria enters the body through open wounds. Affected animals move stiffly and eventually have muscular spasms and die. There is no effective treatment for tetanus, but vaccination is very effective. Affected species: bovine, caprine, equine, ovine, human


Vibriosis (vihb-re-o-sihs) A bacterial infection that causes abortions. Vaccination is an effective preventative, and any aborted fetuses should be destroyed to reduce contamination. Affected species: bovine, caprine, ovine

Warts Skin growths caused by a virus. They most often affect young animals, and can be easily spread from animal to animal. Animals with warts should be separated from others to prevent spreading the virus. Species affected: bovine, equine


A variety of diseases are not caused by specific pathogens. The following is a list of common noninfectious diseases:

Allergies Allergies result when the immune system overreacts to the presence of a substance, usually a protein, that the body identifies as foreign. Although any species can have allergies, they are of greatest concern in dogs, cats, and horses.

Anhydrosis (ahn-hi-dro-sihs) This is not a disease caused by a pathogen, but is a condition in which the animal's sweat glands do not function at all, or function abnormally. Horses with anhydrosis have difficulty controlling their body temperature, especially when working. Species affected: equine

Canine hip dysplasia (CHD) (dihs-pla-ze-ah) A syndrome in dogs in which the head of the femur does not fit tightly into the acetabulum of the pelvis. This results in arthritis in the joint, and pain and lameness in the dog. CHD is a polygenic (multiple-gene) syndrome that is exacerbated by accelerated growth and/or excessive exercise in young dogs. Radiographic evaluation of the hips should be conducted on animals selected for breeding (see Figure 7-9). Species affected: canine


Laminitis (lahm-ih-ni-tihs) A complex disease with many potential causes. Laminitis is the inflammation of the sensitive laminae in the hoof of the animal. Overfeeding, overexercising, stress, systemic infections, and some medications can cause laminitis (see Figure 7-10). Laminitis can result in permanent damage to the hoof and may limit an animal's ability to move comfortably. If laminitis is suspected, a veterinarian should be contacted immediately, especially in the case of horses, where a reduction of athletic ability could result in an inability to serve their purpose. Founder is a term often used interchangeably with laminitis. Founder is more appropriately the term used to describe the chronic condition following an acute bout of laminitis, from which there is permanent damage to the feet, and often malformation of the hooves. Species affected: bovine, equine most often. Could occur in any hooved animal.


Navicular disease (nah-vihck-yoo-lahr) A complex syndrome that occurs when the navicular bone in horses degenerates, causing pain and lameness. Horses susceptible to navicular disease are typically relatively large horses with disproportionately small hooves. Navicular disease can be managed with medications and proper shoeing, but cannot be cured. Species affected: equine

Periodic ophthalmia (of-thahl-me-ah) Also known as moonblindness, periodic ophthalmia is an inflammation of the eye that results in swelling and cloudiness. Deficiency of vitamin B is linked to moonblindness. The horse may lose some or all of its vision. Periodic ophthalmia is a chronic condition, and the symptoms may recur periodically. Species affected: equine

Porcine stress syndrome (PSS) A genetic disease in hogs. Affected animals are easily excited and die due to problems with the circulatory system when stressed. The most effective management practice is to avoid introducing the PSS genes into the herd. Meat from animals with PSS is of less desirable quality than from normal pigs. Species affected: porcine

Recurrent airway obstruction (RAO) This disease is commonly known as heaves. Symptoms include difficulty breathing, either when exercised, or in severe cases, when resting. Horses with RAO often show a heave line, which is an exaggeration of the muscles below the ribs caused by the stress of inhaling and exhaling. Species affected: equine

Torticollis (tor-tih-ko-luhs) A condition in rabbits where themuscles near the cervical vertebrae contract, causing a tilting of the head (see Figure 7-11). Also known as wry neck, torticollis can be a result of pasteurellosis, parasitic infection, or injury. Species affected: rabbits



A wide range of diseases have a nutritional or metabolic component. The most common causes are excess or deficiency of particular nutrients that disrupt the balance of an animal's bodily functions. Nutritional disease can be widely prevented with a well-balanced diet of high-quality ingredients. The following are examples of nutritional diseases:

Anemia (ah-nem-e-ah) A lack of iron in the diet causes anemia, which results in poor growth, reduced immune function, and potentially, death. Anemia can be treated by supplementation of iron. Anemia can also result from blood loss due to parasite infestation. Species affected: all

Azoturia (ahz-o-tur-e-ah) Because azoturia is characterized by stiffness and soreness when returning to work after time off, it is also known as Monday-morning sickness because it was prevalent in working horses on Monday mornings after having Sunday off. Reducing carbohydrates in the diet when not working reduces the incidence of azoturia. Species affected: equine

Bloat (blot) A disease in ruminants that results from fermentation in the rumen, causing excessive gas. Most often, bloat occurs when too much green grass is consumed. Large-breed and deep-chested dogs are also susceptible to bloat from the excessive production of gas in the stomach. Species affected: bovine, canine

Botulism (botch-yoo-lizm) A form of food poisoning, also known as limberneck, caused by consuming feedstuffs that contain the botulism bacteria. The bacteria result in paralysis and death. An antitoxin can reverse the affects of the toxin, but is generally not cost-effective for an entire flock. Species affected: avian

Chronic obstructive pulmonary disease (COPD) Also known as heaves (hevz), COPD is similar to asthma and is a respiratory disease that results from consuming dusty or moldy hay. Animals with COPD have difficulty breathing, and must use their abdominal muscles to exhale, resulting in a muscular heave line that can be observed along the barrel. Minimizing exposure to dust is the best treatment for COPD. Species affected: equine

Colic (kohl-ihck) A broad term used to describe a variety of conditions affecting the digestive tract of horses. The primary symptom of colic is abdominal pain. Colic can be caused by sudden changes in the diet, parasites, diets of poor-quality feed or insufficient forage, or dehydration. Colic symptoms can result from excessive gas (gas colic), blockage of the digestive tract (impaction colic), or twisting of the intestines. Veterinary intervention is usually required to resolve colic. Feeding a diet high in forages, and maintaining a regular deworming program can reduce the incidence of colic. Species affected: equine

Displaced abomasum (DA) Occurs primarily in dairy cattle, when the abomasum shifts in the abdomen, usually after calving. DA is most common in cattle on a high-concentrate diet. Feeding roughages and gradually increasing concentrates to meet nutritional needs is the best prevention. Surgical intervention is sometimes needed to correct the displacement (see Figure 7-12). Species affected: bovine

Eclampsia (e-klahm-se-ah) Also known as milk fever, eclampsia is a loss of muscle control and weakness that is a result of calcium depletion in the body. Eclampsia can be treated with calcium supplementation. Species affected: all mammals

Fatty liver syndrome A disease affecting birds on a high-concentrate diet. Birds get diarrhea and anemia, and may die with no apparent symptoms. Species affected: avian

Fescue toxicosis Feeding animals fescue, a type of grass, creates health problems in some groups. Cattle can get fescue foot (see Figure 7-13), lameness in the hind feet that may result in hoof loss, from grazing on tall fescue. The exact mechanism of spread is not understood. Pregnant and lactating mares should not eat fescue because an endophyte (ehn-do-fit), which is a parasite in the grass, can cause thickening of the placenta and agalactia. Species affected: bovine and equine



Grass tetany (teht-ahn-e) Occurs when cattle are fed a diet that is deficient in magnesium, one of the trace minerals. Animals affected are usually fed on grass that is grown on magnesium-deficient soil, and can be treated by supplementing magnesium (see Figure 7-14). Species affected: bovine

Hardware disease Occurs when cattle ingest metal objects when eating. The metal becomes lodged in the reticulum. Sharp objects may puncture the reticulum and cause injury to internal organs. Removal of metal objects that may be ingested is the best prevention. Cattle magnets are available, which are consumed and rest in the reticulum and attract metal objects. The magnet helps keep the metal from puncturing the reticulum. Species affected: bovine


Hypoglycemia (hi-po-gli-sem-e-ah) A condition that results when blood sugar levels are extremely low. This is usually due to insufficient sugar in the diet. Treatment is supplementation with simple sugars, and increasing the sugar in the diet. Species affected: canine, porcine

Ketosis (ke-to-sihs) A metabolic condition that occurs when carbohydrates in the diet are insufficient to provide for the animal's energy needs. Ketosis is characterized by weight loss, lethargy, and the smell of acetone on the animal's breath. Species affected: bovine, specifically high-producing dairy cattle

Night blindness A lack of vitamin A results in the loss of vision, weakness, and potentially convulsions. Adequate vitamin A in the diet prevents the disease. Species affected: caprine, ovine

Parakeratosis (pahr-ah-kahr-ah-to-sis) A condition that results from zinc deficiency. Zinc deficiency can be either from lack of zinc in the diet, or an imbalance of calcium and zinc. Zinc supplementation controls the condition. Species affected: porcine

Plant toxicity A wide variety of plants produce toxic compounds that can cause illness or death. These toxic compounds can be found in any part of the plant, and different toxins are present at different times of year. Toxic plants must be removed from any areas where animals graze on pasture, or where hay is harvested. Prevalence of plants is very regional, and different plants affect different animals. Species affected: all species

Rickets (rihck-ehts) Symptoms are slow growth and crooked development of bones. Rickets can be caused by an imbalance or deficiency of calcium and phosphorus. Lack of vitamin D, which is essential for use of calcium, may also result in rickets. Species: all

Urinary calculi (yoo-rihn-ar-e kahl-kyoo-li) Small stones from the crystallization of minerals in the urine that form in the urinary tract. The stones may block the urethra, preventing the flow of urine from the bladder. Males are most often affected. In cats, the formation of stones in the urine is known as feline lower urinary tract disease. Adjustments to minerals in the diet can prevent the formation of calculi. Species affected: bovine, caprine, ovine, feline

White muscle disease A disease caused by deficiency of the mineral selenium. White muscle disease is characterized by weakness and lack of muscle control. Animals can be treated with selenium supplementation, but it is important to remember that selenium toxicity can also cause illness. Species affected: bovine, caprine, ovine. Feline and canine can be affected, but this seldom occurs.


Zoonotic diseases are diseases that can be transmitted from animals to humans. They can be transmitted either directly between animal and human, through a vector, such as a mosquito or tick, or through the environment. Diseases that are zoonotic become of concern not only to animal scientists and those in the animal industry, but also to those concerned with public health. The following are examples of zoonotic diseases:

Borreliosis (Lyme disease) (bo-r-ehl-e-oh-sihs) A bacterial disease that is transmitted to humans and dogs through ticks. Lameness and joint swelling are common symptoms in dogs. Treatment with antibiotics is effective. A vaccine is available, and is used in dogs that engage in high-risk activities, such as hunting in areas where borreliosis is endemic. Species affected: canine, human, equine

Brucellosis Brucellosis is caused by different bacteria in dogs than in cattle, but has similar symptoms of abortion and reduced fertility, with very few other definable symptoms. Brucellosis is transmitted through sexual activity, and testing of breeding animals is recommended. Transmission of the bacteria to humans who handle infected fetal material is possible, although highly unlikely. Treatments are available, but outcomes are variable. Species affected: canine, human

Cat scratch disease The bacteria that causes cat scratch disease is endemic in the cat population. Cats do not show symptoms from the bacteria; however, humans can become infected following a scratch or bite. Human symptoms include fever, pain, nausea, and enlarged lymph nodes. People with compromised immune systems should avoid contact with cats that may scratch or bite. Species affected: feline, human

Leptospirosis (lehp-to-spi-rho-sihs) Caused by bacteria, leptospirosis can be transmitted between different species and to humans. The bacteria are transmitted through urine or through contaminated soil and water. There are several strains of leptospirosis, and vaccines are strain-specific. Work with a veterinarian to vaccinate for the strain most prevalent in certain geographical locations. Animals may be asymptomatic (a-sihmp-to-mah-tihck), and show no symptoms, or may have a fever, stiffness, and loss of appetite. Species affected: bovine, canine, porcine, human

Listeriosis (lis-tear-e-o-sihs) Caused by a germ, listeriosis can be spread through contaminated feed or water, and by contaminated bodily fluids. Encephalitic (ehn-sehf-ah-lih-tihck) listeriosis affects the brain, and septicemic (sehp-tih-sem-ihk) listeriosis affects the whole body. There is no vaccine for listeriosis, and the disease often progresses to death. Sanitation is the best preventative. Species affected: most mammals and birds

Plague Caused by the bacteria Yersinia pestis, plague in cats has two forms, bubonic and pneumonic. The bacteria are present in populations of rodents that cats hunt and consume. Treatment with antibiotics can be affective. Care must be taken, especially with pneumonic plague, to prevent spread to humans. Species affected: feline, human

Rabies (ra-bez) Rabies is caused by a virus that can affect any mammal. Wild animals, such as bats, skunks, and raccoons, provide a reservoir for the disease organism. Rabies can be transmitted through the saliva of an infected animal when it bites another animal. Rabies is a major human health concern, and veterinarians may recommend vaccinating horses in areas where rabies in the wild population is high. Affected animals show nervous and aggressive behavior and excessive salivation. There is no cure. Species affected: all mammals

Salmonellosis (sahl-muh-nehl-o-sihs) Infection with the Salmonella bacteria results from consumption of the bacteria through food, or exposure to the bacteria through infected materials. Salmonella infection results in vomiting and diarrhea. Antibiotics can be effective for treatment; sanitation is the best preventative. Salmonellosis can be transmitted from animals to humans, and is a primary zoonotic disease of concern. Species affected: all

Toxoplasmosis (tocks-so-plahz-mo-sihs) A disease caused by a protozoal parasite in cats. Symptoms include fever, diarrhea, muscle weakness, and other neurological signs. Pregnant women can become infected with the parasite by cleaning a litter box of infected cats. Infection can result in birth defects, so pregnant women should not handle cat fecal material, or clean litter boxes. Species affected: feline

Tularemia (too-lah-rem-e-ah) Primarily affects cats that hunt outdoors and consume rodents that harbor the bacteria. It can also be contracted through ticks. Symptoms include fever, mouth ulcers, and eventually damage to the liver and bone marrow. Infected animals often die, and can transmit the disease to humans through bites or bodily fluids. Species affected: feline

West Nile encephalitis (WNE) (ehn-sehf-ah-li-tihs) A relatively new disease in the United States, West Nile encephalitis is carried by mosquitoes that have bitten a bird that carries the WNE virus. The infected mosquito then bites an animal and infects the animal with the virus. Symptoms are similar to other diseases that affect the central nervous system: anorexia, circling, and loss of coordination. A vaccine does exist for WNE, and treatment can be effective. Species affected: canine, equine, human


Parasites are any of a variety of organisms that live by "stealing" nutrients from their hosts. Parasites can be categorized as internal or external, based on where they attack the host. They can either carry other diseases, or cause damage to the body directly. Animals with heavy loads of parasites can show symptoms of malnutrition due to the quantity of nutrients the parasites are taking. Animals that are infested with parasites grow more slowly and produce less than animals without parasites. Some parasites can cause permanent damage to affected organs.

Parasites can be treated with a variety of medications that kill or remove the parasites. Anthelmintics (an-thehl-mihn-tihcks) are medications that are used to kill internal parasites. Understanding the life cycle of different parasites, and breaking that life cycle, is also effective in controlling parasites.


Ectoparasites (ehck-to-pahr-ah-sits), or external parasites, live on the outside of the body of an animal. They are vectors for a variety of diseases, often cause skin irritation, and may cause anemia due to the amount of blood they consume. Ectoparasites can often be identified visually with the naked eye. The following are some ectoparasites:


Fleas An insect that sucks blood from the host. A heavy infestation of fleas can remove enough blood to result in anemia, and even death, for the host (see Figure 7-15). Fleas are large enough to be visually seen. Also, the "flea dirt" or excrement, may be noted, especially in the inguinal region. Fleas can also be intermediary hosts for other diseases and parasites. Some animals, especially dogs, have allergic reactions to flea saliva when they are bitten. Although fleas will bite humans, they do not stay on human hosts. There are a variety of treatments and prevention programs for fleas. Consult with a veterinarian, and ensure that products are approved for use in the species of concern. Species affected: dogs, cats, humans

Flies A wide variety of flies affect livestock. Danger from flies comes from two sources: transmission of the disease through biting, and irritation of the animal that increases stress and decreases growth and production. Flies can be treated with insecticides, and by eliminating breeding areas. Species affected: all species

Lice Blood-sucking insects that affect a variety of species (see Figure 7-16). Lice infestations can be prevented by isolating new animals and ensuring they are not infested before exposing the whole herd. Topical treatments are effective for eliminating lice. Species affected: all species, by species-specific varieties

Maggots The larvae of insects, usually flies, that can live in animal tissues. A maggot infestation results when they lay eggs on an animal, usually in an area that is wet or where the skin is damaged, and the eggs hatch and feed on the tissue. Species affected: all species



Mites Small spider-like insects that suck blood from their hosts. A variety of mites affect different species of animals (see Figure 7-17). Mites cause mange (ma-nj), a skin disease characterized by itching, redness, and hair loss. The two major varieties of mange are sarcoptic (sahr-kohp-tihck) and demodectic (deh-mo-dehck-tihck), each caused by mites of the same name. Sarcoptic mange is characterized by severe itching caused by the mites burrowing under the skin. The severe itching can result in abrasion of the skin, leaving it susceptible to secondary infection. Demodectic mange is less severe than sarcoptic mange, and is characterized by more mild, localized, itching. Because mites bite their hosts, they can also spread some diseases. Species affected: all species

Mosquitoes One of the most dangerous external parasites are mosquitoes. Although the quantity of blood they remove is minimal, mosquitoes are vectors for a wide variety of diseases and other parasites that they can spread to most animal species.

Elimination of breeding ground is the best way to minimize mosquito infestation. Species affected: all species


Ringworm An infectious skin disease caused by a fungus that can be easily spread to other animals and to humans. Ringworm is characterized by a round patch of hairless skin, and can occur anywhere on the body (see Figure 7-19). Topical disinfection of affected sites is an effective treatment. Affected animals should be kept separate from nonaffected animals to minimize spread. Sanitation is important to prevention of ringworm. Species affected: all species

Ticks Several species of ticks affect animals. Ticks are blood-sucking insects that also carry organisms that cause other diseases (see Figure 7-18). Species affected: all species


Endoparasites (ehn-do-pahr-ah-sits) are parasites that live in the body of the host during their infective stage. Most endoparasites are commonly known as "worms," or "internal parasites." Although the infective stage is internal to the host, many endoparasites spend at least some part of their life cycle outside the body of the host. The following are some of the endoparasites that affect animals:

Ascarids (ahs-kah-rids) Ascarids (large roundworms) are major parasites of concern in animals. Different species of ascarids affect different species of animals. Mature worms in the intestines release eggs that are shed in the feces, and then are ingested by an animal that is grazing or pecking in the grass. The eggs hatch in the digestive tract, then the larvae invade the walls of the intestinal tract and migrate through the body. Some larvae end up in the lungs, where they are coughed up and swallowed again to mature in the intestinal tract, shed eggs, and continue the cycle. Some larvae become encysted in the tissue of the host animal. In the case of dogs and cats, pregnancy can cause the reactivation of these encysted parasites, and they can be transmitted to the young through the placenta in dogs, or through the milk in cats (see Figure 7-20). Species affected: canine, equine, feline, porcine


Bots (bahts) Parasites that live in the stomach of horses during the larval stage. Bot flies lay yellowish eggs on the horse (the location depends on species of fly), that then ingests the eggs that hatch and mature in the stomach. The mature larvae are passed out in the feces, where they complete maturation to the fly stage, and the cycle begins again (see Figure 7-21). Species affected: equine

Coccidiosis (kohck-sihd-e-o-sihs) A protozoal parasite that causes irritation of the intestinal tract, leading to diarrhea that is often bloody. Animals do not eat well, lose weight, and may die. Coccidiosis can be treated with antibiotics, and many starter feeds for birds contain coccidiosis medication. Different species of the parasite affect different species of animals and birds, so it is important to use the medicated feed for the correct species. Species affected: all livestock and avian species

Gapeworms A parasite that lives in the trachea of birds, and can interfere with breathing. Birds ingest parasite-infected snails or worms, so range-fed birds are at the most risk of infection (see Figure 7-22). Species affected: avian

Heartworms Heartworms affect both dogs and cats, although dogs are the primary hosts. Heartworm is transferred when a mosquito bites an infected dog, picks up the larval worm, and then passes it to another dog through a bite. The worms lodge in the heart to mature, and cause exercise intolerance and eventually death (see Figure 7-23). Laboratory tests can detect the presence of heartworms, and there are effective treatments. Excellent preventative medications are available, and it is recommended that dogs in places where heartworm is endemic are maintained on a preventative. Species affected: canine, feline



Liver fluke A parasite that lives in the liver. The eggs are shed through the manure, and the larvae then hatch. The larvae mature in an intermediate host, the snail. After maturing, the larvae leave the snail and are ingested again when the larvae attach to blades of grass. Species affected: caprine, ovine

Lungworm Thread lungworms and hair lungworms live in the lungs. Eggs are laid in the lungs, coughed up, and swallowed into the digestive tract. In the digestive tract, the eggs hatch and larvae are passed with the feces. Larvae mature in an intermediate host such as snails or slugs, are ingested by animals, and migrate through the intestines back to the lungs (see Figure 7-24). Species affected: sheep, goats



Pinworms Small worms that travel through the large intestine and locate in the anus, where they cause itching and discomfort. Affected animals rub their tails to combat the itching. Loss of tail hair and observed frequent itching are signs that pinworms may be present. Species affected: equine

Strongyles (strohn-gil) There are large and small varieties of strongyles. Large strongyles are the most dangerous and migrate through the body to the liver, lungs, and intestinal wall at different stages of the life cycle. They attach to the organs to suck blood, and cause damage at the points of attachment. They can also cause clots in the circulatory system. Small strongyles live exclusively in the intestine. Heavy loads of parasites may lead to colic in horses, and signs of malnutrition in any affected species. Species affected: canine, equine, feline



Tapeworms Segmented worms that live in the intestines of warm-blooded animals (see Figures 7-25 and 7-26). Tapeworms must spend part of their lives in an intermediate host. Animals then consume the intermediate hosts and become infected with tapeworms.



A wide range of diseases and parasites affect animals. Diseases can be transmitted directly from animal to animal, through the environment, or through vectors. Preventing disease is an important part of animal management, and can be done through maintaining a clean and sanitary facility, appropriate vaccination, purchase of new animals that are in good health, and isolation of new animals until their health status is confirmed. Vaccination can assist animals' immune systems in fighting off disease-causing organisms, and judicious use of antibiotics can ensure the continuing good health of the animals.


1. What disease affects the central nervous system and is a zoonotic disease that affects all mammals?

2. Bacteria and viruses are examples of what type of disease-causing organisms?

3. What is the process of introducing an antigen to the body so that the immune system will respond with antibodies?

4. What is antibiotic resistance, and why is it a concern in treatment of animal disease?

5. What disease is the degeneration of a bone in the foot of the horse?

6. What ectoparasite causes mange?

7. What endoparasite is carried by mosquitoes and affects both dogs and cats?

8. What management steps can be taken to decrease the incidence of disease?

9. What is the difference between a modified live and a killed vaccine?

10. What internal parasite has the largest impact on the swine industry?

11. What is the name of the group of chemicals that are used to treat internal parasites in animals?

12. List three diseases that affect the central nervous system, and the species in which they are found.

13. What is a vector?

14. For what disease, and in what species, do many states have a law requiring vaccination?

15. Select one of the diseases listed in this chapter. Research and write a paper on the disease, including species affected, causes, symptoms, and treatment. What management practices can be used to prevent the disease?
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Author:Brady, Colleen
Publication:An Illustrated Guide to Animal Science Terminology
Geographic Code:1USA
Date:Jan 1, 2008
Previous Article:Chapter 6 Animal behavior.
Next Article:Chapter 8 Beef cattle.

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