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Abdominal Tuck

The appearance of an animal that is hunching its back and drawing up its abdomen in at attempt to expand its lungs.


Lesions filled with pus that is essentially dead white blood cells that had come in to fight the bacteria causing the lesions. Abscesses often are walled off by connective tissue in the body’s attempt to contain the site of infection.


Sudden and severe. In BRD, acute onset is more easily detected than sub-acute disease, so treatment may be administered sooner and therefore more effectively.


Contamination or spoilage.


Loss of appetite.

Actinobacillus pyogene

A minor bacterial species in the BRD complex.


Single-cell organisms that can infect tissue, multiply extremely rapidly, and secrete toxins (poisons) that kill healthy tissue cells and immune system cells.

Bacterial Toxins

The poisons produced by bacteria. There are two types: those secreted by the bacteria (exotoxins) and those contained within the bacteria (endotoxins).


Bovine Herpes Virus-1, more commonly known as IBR, or infectious bovine rhinotracheitis. It is one of the viruses that may infect the lungs and predispose them to bacterial infection. IBR is associated with other conditions, such as reproductive disease, as well.

Bovine Respiratory Disease

A complex of diseases that affect cattle’s lungs. Abbreviated BRD, it can involve viruses, bacteria, or a combination of both. BRD is considered the most important cause of economic losses for the cattle industry.

Gagnea, MI et al. J Vet Diagn Invest 2006; 18: 18-24.

Bovine Viral Diarrhea Virus



Bovine Respiratory Syncytial Virus, a pathogen commonly involved in the BRD complex of infections.


Bovine Viral Diarrhea Virus, a pathogen responsible for widespread systemic conditions. Its role in BRD is primarily that it suppresses the immune system, so an animal’s ability to resist or fight infection is compromised.


Refers to an agent or event responsible for a condition or disease. Viruses and bacteria, for example, are causative agents of BRD.

Chlamydia spp.

A minor group of bacterial species in the BRD complex.


Animals that have been treated two or probably more times but do not regain health or performance. No additional treatment is given to these animals because it would not be cost-effective.


Microscopic hair-like structures that line the upper respiratory tract. They trap pathogens which can then be eliminated from the body when the animal coughs.


Refers to the action of cilia.


Animals mingling close together, such as occurs during transportation and in crowded pens. It is an excellent opportunity for pathogens to be passed from one animal to another.


Refers to colostrum, a dam’s first milk. In cattle health, the most common use of this word is in conjunction with antibodies – colostral antibodies, those received by a calf when it first suckles colostrum after birth.

Disease Complex

A multitude of factors – pathogens and management practices – that result in a disease event such as BRD.


Air trapped in the lungs due to diseased tissue. It can further compromise lung function.


What cattle eat. This may be forage or feed.

Flunixin Meglumine

A non-steroidal anti-inflammatory drug (NSAID). It does not incur the immunosuppressive effects of steroidal drugs.


A unique injectable antibiotic of the fenicol class. It is both bacteriostatic (inhibits bacterial growth) and bactericidal (kills bacteria).


A ruminal function that involves bacteria breaking down cellulose and other components of cattle diets/rations to aid the animal’s digestion and absorption of its feedstuffs.


Refers to a substance that is the consistency of gelatin – neither liquid nor solid.


Hormones released in response to inflammation. They can suppress the immune system, which compromises an animal’s ability to resist or fight infection.

Histophilus somni

A major bacterial species in the BRD complex. Incidence of H. somni infections may be related to livestock genetics and production practices in various regions of the country.

Griffin, D. “Etiology, pathogenesis, and clinical signs of bovine respiratory disease.” Bovine Respiratory Disease Sourcebook for the Veterinary Professional. Veterinary Learning Systems 1996, pp 6-11.


The ankle of an animal.

Immune Status

The degree to which an animal is resistant to any given pathogen(s). Immune status is influenced by natural immunity and/or vaccination.


Describes the ability of an organism or stressor to suppress the immune system.

Infectious Bovine Rhinotracheitis

See BHV-1.


A physical response to irritation or infection. It results when immune system cells attempt to correct the situation. Inflammation is characterized by redness, swelling, and heat.


In the vein.

Irreversible Damage

Tissue that is damaged – such as by lung lesions – and might heal but never return to normal function.


Tissue destruction and possibly irreversible scarring. Lesions caused by bacteria in the lungs can affect an animal’s performance for its entire life.

M. haemolytica type 1A

A serotype of Mannheimia haemolytica.

M. haemolytica type 2A

A serotype of Mannheimia haemolytica.

Mannheimia haemolytica

A major bacterial species in the BRD complex. M. haemolytica is the most commonly isolated bacterium in fatal cases of BRD in the High Plains and Midwest United States.

Griffin, D. “Etiology, pathogenesis, and clinical signs of bovine respiratory disease.” Bovine Respiratory Disease Sourcebook for the Veterinary Professional. Veterinary Learning Systems 1996, pp 6-11.


Thin layers of fat deposited within muscle tissue. A high degree of marbling in beef is associated with tenderness and juiciness.


Hiding, concealing, or covering up.


An accurate average determined by a special mathematical equation.


A thin layer of tissue that covers a surface, lines a cavity, or divides a space or organ. Mucus membranes are the most relevant to BRD. They secrete mucus to trap pathogens entering the respiratory tract.


A very minor nutrient, such as selenium (unlike protein, a major nutrient), that can nonetheless be important in the overall health of an animal and its disease resistance.


The end of life, death loss. The word mortality is often used in conjunction with the word morbidity, which means sickness.


A procedure in which a dead animal is cut open for observation of diseased versus healthy tissue and organs. The human equivalent is autopsy.

Pasteurella multocida

A major bacterial species in the BRD complex. P. multocida is more commonly isolated in fatal cases of BRD in younger cattle than in fatal cases in yearling cattle.

Griffin, D. “Etiology, pathogenesis, and clinical signs of bovine respiratory disease.” Bovine Respiratory Disease Sourcebook for the Veterinary Professional. Veterinary Learning Systems 1996, pp 6-11.


An organism that can cause disease.




The degree of power a pathogen has to cause disease.

Peak Plasma Concentration

The highest level of drug – for example florfenicol or flunixin meglumine – that occurs in the plasma portion of blood after administration of the drug.

Performance setback

A reduction in average daily gain and feed efficiency, usually due to a disease event such as BRD.


Parainfluenza-3, a virus commonly involved in the BRD complex of infections.


After death.


The act of multiplying exact copies. Bacteria, for example, replicate by dividing in half. They can do this every 30 minutes, which helps explain acute onset of BRD


A large “vat” in the digestive system where feedstuffs are initially digested. Because cattle diets/rations contain mostly hard-to-digest feedstuffs, the animals can regurgitate contents of the rumen for further chewing to expose more surface area for rumen bacteria to break down. Cattle spend a large amount of time “chewing their cud” or “ruminating.” It’s one of the reasons cattle can exist on forage that other animals could not digest.


The degree to which an organism can be suppressed or killed by an antibiotic.


A subset of an organism based on its unique structure.

Severe depression

A severe lack of interest in an animal’s surroundings. It is typically observed as an animal with its head and ears down, dull eyes, standing apart from pen or herd mates, and reluctance to move, eat, or drink.

Shipping Fever

BRD that occurs shortly after transportation.


The appearance of an animal that does not have a full rumen.


Conditions that cause stress in cattle, which can lower their immunity to disease. Common stressors are weather, weaning, handling, and transportation.


Under the skin, referring to injections that are administered in that manner rather than into the muscle or in a vein.


The degree to which an animal is likely to become infected by any given pathogen(s).


Short lasting.