Type of Animal Diseases

Disease

Culmination of various defects, abnormalities, excesses, deficiencies and injuries at cellular and tissue level resulting in clinically apparent dysfunction. A condition that impairs normal tissue function as a result of infection or failure of the animal to counteract stimuli, stresses, or insults leading to injury or illness.

Exciting cause

Immediate factor (germ or pathogen) responsible for a particular disease.

Contributory or predisposing cause

Factor which renders the disease more serious such as poor nutrition, climate, age, and fatigue.

Development of disease

Incubation period (time between infection and first signs/symptoms); Prodromal period (appearance of mild signs/symptoms); Period of illness (disease at its height); Period of decline (signs and symptoms subside); Period of convalescence (health is restored).

Modes of disease transmission

Diseased animals, polluted water sources, transporting vehicles, carrier animals, carrion feeders, arthropods, airborne pathway, and contaminated facilities or equipment.

Modes of entry of pathogens

Respiratory tract, wound contamination, mucous membranes of the eyes, genital tract, teat canal, navel cord, contaminated instruments, and insect bites.

Termination of disease

Full recovery, partial recovery, or death.

Requirements for the study of disease

Nature of the pathogen (etiology), establishment and progression of disease, effects on function and structure, and end effect (recovery or death).

Infectious disease

Disease caused by pathogens such as viruses, bacteria, protozoa, fungi, and helminths.

Contagious disease

Infectious disease transmissible from one individual to another through direct or indirect contact.

Non-infectious disease

Disease caused by mechanical ailments, digestive disturbances, intoxications, nutritional deficiencies or excesses, cell growth abnormalities, genetic disorders, or metabolic disorders.

Acute disease

Quick and short-lived condition (e.g., African swine fever, Avian influenza, Anthrax).

Chronic disease

Slow and long-lasting condition (e.g., Tuberculosis and Johne's disease).

Subacute disease

Condition between acute and chronic.

Peracute disease

Disease that kills the host quickly.

Latent disease

Condition in which the causative agent remains inactive for a period before becoming active and producing signs or symptoms.

Epidemic

Disease spreading among people in a relatively short period of time.

Epizootic

Extensive outbreak of animal disease that is widely prevalent.

Endemic

Disease constantly present in a human population in a locality.

Enzootic

Disease continuously present among groups of animals without rapid spread.

Pandemic

Worldwide epidemic disease (e.g., AIDS and COVID-19).

Panzootic

Animal disease that rapidly spreads across large regions or worldwide (e.g., FMD and H5N1 bird flu).

Sporadic disease

Disease that suddenly appears and disappears, affecting one or more animals.

Incidence

Number of new cases in a population; commonly used for acute diseases.

Prevalence

Number of both old and new cases; commonly used for chronic diseases.

Local infection

Infection limited to a relatively small area of the body.

Systemic or generalized infection

Infection that spreads throughout the body via blood or the lymphatic system.

Bacteremia

Presence of bacteria in the blood.

Septicemia

Spread of multiplying pathogenic microorganisms and their toxins through circulating blood.

Toxemia

Presence of toxins in the blood.

Primary infection

Initial acute infection that causes illness.

Secondary infection

Infection caused by opportunistic microbes after the primary infection weakens the body's defenses.

Inapparent (subclinical) infection

Infection that does not cause noticeable illness.

Idiopathic disease

Disease with no established cause and cannot be experimentally reproduced.

Iatrogenic disease

Disease caused by medical intervention or clinician-induced damage.

Nosocomial infection

Hospital-acquired infection resulting from a hospital stay.

Genetic disease

Disease caused by inherited or chromosomal abnormalities. Commonly recessive or sex-linked and may result in fetal death or congenital defects.

Examples of genetic diseases

Rod-cone dysplasia, Spider lamb syndrome, Von Willebrand disease, Severe combined immunodeficiency of Arabian horses, Duchenne muscular dystrophy, lactose intolerance, cystinuria, and lysosomal storage diseases.

Diagnosis of genetic diseases

Karyotyping or identification of abnormal genes or gene products.

Ways of DNA damage

Strand breaks, altered base sequences, and abnormal cross-links between base pairs.

Metabolic alterations

Result from nutritional imbalance, altered lipid metabolism, hormonal imbalances, and protein-energy malnutrition.

Vitamin A

Deficiency - anorexia, weight loss, ataxia, conjunctivitis, skin lesions, respiratory ailments, susceptibility to infection, hydrocephalus, and cleft palate. Excess - imbalance in bone remodeling, artery and vein degeneration, dehydration, CNS depression, and joint pain.

Vitamin D

Deficiency - rickets, lethargy, loss of muscle tone, swelling and bending of bones. Excess - anorexia, weakness, vomiting, calcification of soft tissues, mineralization of long bones, dry and brittle hair, and muscle atrophy.

Vitamin E

Deficiency - skeletal muscle degeneration, reproductive failure, retinal degeneration, and steatitis.

Vitamin K

Deficiency - coagulopathy. Excess - hypersensitivity reaction.

Vitamin B1 (Thiamine)

Deficiency - failure to grow, weight loss, neurological abnormalities, and damage to the nervous system and heart.

Vitamin B2 (Riboflavin)

Deficiency - anorexia, weight loss, muscular weakness, flaking dermatitis, and eye lesions.

Vitamin B6 (Pyridoxine)

Deficiency - anorexia, weight loss, convulsions, muscle twitching, and anemia. Excess - impaired motor control, balance, and muscle weakness.

Niacin

Deficiency - anorexia, weight loss, oral ulcerations, salivation, and bloody diarrhea. Excess - bloody feces and convulsions.

Pantothenic acid

Deficiency - erratic food intake, coma, increased respiratory and heart rates, convulsions, gastrointestinal symptoms, reduced antibody production, poor growth, and fatty liver.

Biotin

Deficiency - scaly dermatitis.

Vitamin B12 (Cobalamin)

Deficiency - poor growth, weight loss, and anemia.

Calcium

Deficiency - nutritional secondary hyperparathyroidism and skeletal abnormalities. Excess - skeletal aberrations in growing large-breed puppies.

Phosphorus

Deficiency - reduced weight gain, poor appetite, and bowing or swelling of forelimbs.

Magnesium

Deficiency - poor weight gain, irritability, convulsions, and hind-leg paralysis. Excess - urolith formation in cats.

Sodium

Deficiency - restlessness, increased heart rate and water intake, and dry mucous membranes.

Potassium

Deficiency - poor growth, restlessness, muscle paralysis, and weakness.

Chloride

Deficiency - reduced weight gain and weakness.

Iron

Deficiency - poor growth, pale mucous membranes, lethargy, weakness, and diarrhea. Excess - oxidative damage to gastrointestinal and other tissues.

Copper

Deficiency - loss of hair pigmentation and anemia.

Zinc

Deficiency - poor growth, anorexia, testicular atrophy, parakeratosis, and achromotrichia.

Selenium

Deficiency - anorexia, depression, dyspnea, coma, and muscular degeneration. Excess - pulmonary edema.

Cobalt

Deficiency - poor growth and anemia.

Iodine

Deficiency - goiter.

Physical agents

Trauma, heat, cold, and radiation that cause tissue damage.

Hyperthermia

High environmental temperature leading to dehydration, increased blood pH, hemoglobin concentration, and erythrocyte counts.

Heatstroke

Causes degenerative changes in the myocardium, renal tubules, and brain.

Malignant hyperthermia

Associated with abnormalities in the ryanodine receptor.

Hypothermia

Low body temperature due to exposure to cold environments, especially in poorly nourished animals.

Cold damage

Causes cellular injury, intracellular water crystallization, protein changes, membrane damage, vascular impairment, vasoconstriction, and thrombosis.

Radiation injury

Caused by UV rays, X-rays, gamma rays, and particle radiation.

Effects of radiation

Cell swelling and chromosomal damage (breakage, deletion, and translocation)