Glossary of Terms

From: "Current Concepts of Bovine Mastitis", National Mastitis Council, 1996.

Acute mastitis: Udder inflammation characterized by sudden onset, redness, swelling, hardness, pain, grossly abnormal milk, and reduced milk yield.

Alpha toxin: A poison produced by Staphylococcus aureus that causes blood vessal constriction and blood clotting.

Alveolus: Microscopic, spherical milk-producing unit of the udder, composed of epithelial cells.

Anaerobic (bacteria): Bacteria that grow in the absence of oxygen.

Antibodies: Proteins synthesized by organs of the cows' immune system that aid in the elimination of foreign substances such as microorganisms.

Backflushing: An automated system for sanitizing teat cup liners between cows.

Bacteremia: Presence of bacteria in the blood stream.

Casein: The major protein found in milk.

Chronic mastitis: Udder inflammation that continues over a long period of time, with progressive development of scar tissue and simultaneous reduction in milk yield.

Clinical mastitis: Udder inflammation characterized by visible abnormalities in the udder or milk.

Cluster: The milking unit assembly containing teat cup shells and liners, short milk and pulsation tubes, claw, and long milk and pulsation tubes.

Coliform(s): Rod-shaped bacteria originating from the intestinal tract.

Complement: An antibacterial protein found in milk that inhibits bacterial growth.

Contagious (microorganisms): Bacteria growing in the udder that are spread from cow to cow.

Corticosteroid: An anti-inflammatory hormone.

Cytokine: A protein produced by leukocytes, which regulates the antibacterial activity of other leukocytes.

Droplet impact: Microscopic droplets of milk, possibly containing microorganisms, that impact against the teat orifice near the end of milking, which may initiate a new udder infection.

Edema (of the udder): Swelling of the udder or teats caused by the accumulation of fluid below the skin.

Endotoxin: A poison produced by Escherichia coli that causes systemic response (fever, diarrhea, inappetence) to coliform mastitis in cows.

Enterococci: Gram-positive, catalase-negative cocci.

Enterotoxin: A poison produced by Staphylococcus aureus that causes illness when injested by humans.

Environmental (microorganisms): Bacteria growing in the cows' environment that contact the udder and teats causing infection.

Epidemiology: A study of the relationships of various factors determining the incidence and prevalence of mastitis in a herd.

Epithelial cells: Cells in the udder comprising an alveolus that synthesize and secrete milk.

Fibrosis: The replacement of infected tissue areas with fibrous connective or scar tissue.

Foremilk: The first streams of milk stripped from the udder prior to milking.

Forestrip: Process by which the first few streams of the milk are expressed from the teat prior to milking to observe for abnormalities and to flush the teat canal.

Immunoglobulin: See Antibodies.

Incidence (of mastitis): Rate at which mastitis cases occur.

Infection: The presence of microorganisms growing in the udder.

Inflammation: A condition in which the cow's body seeks to eliminate or neutralize invading microorganisms and repair damaged tissue.

Involution: The process by which udder tissue reverts to a non-milk-producing state after drying off.

Keratin: A waxy substance produced by cells lining the teat canal that serves as a plug between milkings and aids in reducing penetration by microorganisms.

Lactoferrrin: An antibacterial protein found in milk that inhibits bacterial growth.

Lactoperoxidase/thiocyanate/hydrogen peroxide system: An enzyme complex in milk that inhibits bacterial growth.

Lactose: The sugar present in milk.

Let-down: A process through which milk is squeezed out of milk-producing tissue by the action of the hormone, oxytocin.

Leukocyte: White blood cell.

Leukotriene: Arachidonic acid metabolites having potent pharmacological effects.

Liner slip: Condition whereby the teat cups slide down the surface of the teat, often accompanied by a squawk, caused by improper liner design, cluster weight, vacuum fluctuations, and milking wet teats.

Lipase: An enzyme that breaks down butterfat, leading to rancidity of milk.

Lymphocyte: A type of white blood cell involved in udder immunity.

Macrophage: A type of white blood cell that engulfs and destroys microorganisms in milk.

Major histocompatibility complex: A genetic region of chromosomes responsible for the production of products that function in cell to cell communication.

Mastitis: Inflammation of the udder, most commonly caused by infecting microorganisms.

Microorganism: Small, one-celled or multicellular organisms that can only be viewed with a microscope.

Milking unit: An assembly consisting of shells, inflation, claw, air and milk tubes, and pulsator.

Milking vacuum: The vacuum to which the teat of the cow is exposed when the inflation is open.

Milk tube or milk hose: The tube that conveys milk from the claw or reservoir to a pipeline or bucket.

Milk-producing tissue: The glandular part of the udder that produces milk.

Mycobacteria: Slender, acid-fast microorganisms resembling the bacilli that cause tuberculosis.

Mycoplasma: Microorganisms that are intermediate in size between bacteria and viruses.

Nonbacterial mastitis: A form of mammary inflammation in which no microorganisms can be isolated from milk samples.

Neutrophil: A type of white blood cell that engulfs and destroys microorganisms in milk.

Opsonins: Antibodies that function by preparing microorganisms for engulfment by white blood cells.

Oxytocin: The hormone that causes milk let-down.

Pathogen: Any microorganism that causes disease.

Peracute mastitis: A form of udder inflammation with systemic involvement that includes depression, rapid pulse, dehydration, and diarrhea.

Phagocytosis: The process by which white blood cells engulf microorganisms.

Plasmin: An enzyme that breaks down fibrin clots as well as milk casein.

Polymorphonuclear neutrophilic leukocyte: A type of white blood cell that engulfs and kills bacteria.

Prevalence (of mastitis): The percent of cows or mammary gland quarters that are infected at any one time.

Pseudomonads: Gram-negative, catalase-positive, motile, rod-shaped microorganisms.

Pseudopodia: Finger-like projections of leukocytes, which aid in the engulfment of bacteria.

Pulsation ratio: The amount of time a pulsator creates vacuum to open the liner compared with the amount of time it admits air to collapse the liner.

Pulsation rate: Number of pulsation cycles per minute.

Pulsator: A device that varies the vacuum (pressure) between the liner and shell, thus opening and closing the liner to provide milk and massage to the teat.

Serum albumin: A blood protein that leaks into the mammary gland when inflamed.

Scar tissue: Fibrous tissue accumulating in the udder after infection that permanently replaces milk-producing tissue and prevents drugs from reaching sites of infection.

Somatic cells: Includes mainly white blood cells that move into the udder during inflammation, and a small percentage of epithelial cells from milk producing tissues.

Spontaneous recovery: The ability of a cow to cure herself of an udder infection without the aid of antibiotics or other drugs.

Staphylococci: Spherical bacteria that grown in grape-like clusters.

Stray voltage: Small electrical currents on milking equipment originating on or off the farm, which may elicit a response from cows.

Streptococci: Spherical bacteria that grow in chains.

Strippings: That portion of milk left in the udder after machine detachment.

Subacute clinical mastitis: A form of udder inflammation that is mildly clinical where symptoms include clots or flakes in milk.

Subclinical mastitis: The most prevalent form of udder inflammation. It cannot be detected visually but causes the greatest economic loss.

Summer mastitis: A form of mastitis characterized by thick, foul-smelling secretion (pus) usually caused by Actinomyces pyogenes and Peptococcus indolicus.

Teat canal: Passageway through which milk flows from the udder. It is surrounded by a muscle sphincter that maintains tight closure between milkings.

Toxemia: A condition caused by toxins or poisons that enter the bloodstream and cause illness.

Toxin: A poison produced by microorganisms that kills cells.

Transferrin: A blood protein that transports iron into the mammary gland.

Vacuum pulsator line: The pipe or line that supplies vacuum to the pulsator(s).

Vacuum pump: A pump that removes air from the milking system to develop partial vacuum.

Walling-off: A condition in which microorganisms in the udder become enclosed (walled off) by scar tissue and are inaccessible to drugs.

Wet milking: The milking of teats that have not been thoroughly dried.