The classic symptoms of pertussis are a paroxysmal cough, inspiratory whoop, and fainting, or vomiting after coughing. The cough from pertussis has been documented to cause subconjunctival hemorrhages, rib fractures, urinary incontinence, hernias, and vertebral artery dissection. Violent coughing can cause the pleura to rupture, leading to a pneumothorax. Vomiting after a coughing spell or an inspiratory whooping sound on coughing, almost doubles the likelihood that the illness is pertussis. The absence of a paroxysmal cough or posttussive emesis, though, makes it almost half as likely.

The illness usually starts with mild respiratory symptoms, mild coughing, sneezing, or a runny nose. This is known as the catarrhal stage. After one to two weeks, the coughing classically develops into uncontrollable fits, each with five to ten forceful coughs, followed by a high-pitched "whoop" sound in younger children, or a gasping sound in older children, as the person tries to inhale (paroxysmal stage).

Coughing fits can occur on their own or can be triggered by yawning, stretching, laughing, eating, or yelling; they usually occur in groups, with multiple episodes on an hourly basis throughout the day. This stage usually lasts two to eight weeks, or sometimes longer. A gradual transition then occurs to the convalescent stage, which usually lasts one to four weeks. This stage is marked by a decrease in paroxysms of coughing, both in frequency and severity, and a cessation of vomiting. A tendency to produce the "whooping" sound after coughing may remain for a considerable period after the disease itself has cleared up.

The time between exposure and the development of symptoms is on average 7–14 days (range 6–20 days), rarely as long as 42 days.

The incubation period is 5–7 days (with a range of 3–10). Symptoms can include a harsh, dry cough, retching, sneezing, snorting, gagging or vomiting in response to light pressing of the trachea or after excitement or exercise. The presence of a fever varies from case to case.

Although kennel cough is considered to be a multifactorial infection, there are two main forms. The first is more mild and is caused by B. bronchiseptica and canine parainfluenza virus infections, without complications from canine distemper virus (CDV) or canine adenovirus (CAV). This form occurs most regularly in autumn, and can be distinguished by symptoms such as a retching cough and vomiting. The second form has a more complex combination of causative organisms including CDV and CAV. It typically occurs in dogs that have not been vaccinated and it is not seasonal. Symptoms are more severe than the first form, and may include rhinitis, conjunctivitis, and fever in addition to a hacking cough.

Bronchitis may be indicated by an expectorating cough, shortness of breath (dyspnea), and wheezing. On occasion, chest pains, fever, and fatigue or malaise may also occur. In addition, bronchitis caused by Adenoviridae may cause systemic and gastrointestinal symptoms as well. However, the coughs due to bronchitis can continue for up to three weeks or more even after all other symptoms have subsided.

Acute bronchitis, also known as a chest cold, is short term inflammation of the bronchi of the lungs. The most common symptom is a cough. Other symptoms include coughing up mucus, wheezing, shortness of breath, fever, and chest discomfort. The infection may last from a few to ten days. The cough may persist for several weeks afterwards with the total duration of symptoms usually around three weeks. Some have symptoms for up to six weeks.

Acute bronchitis usually lasts a few days or weeks. It may accompany or closely follow a cold or the flu, or may occur on its own. Bronchitis usually begins with a dry cough, including waking the sufferer at night. After a few days, it progresses to a wetter or productive cough, which may be accompanied by fever, fatigue, and headache. The fever, fatigue, and malaise may last only a few days, but the wet cough may last up to several weeks.

Should the cough last longer than a month, some physicians may issue a referral to an otorhinolaryngologist (ear, nose and throat doctor) to see if a condition other than bronchitis is causing the irritation. It is possible that having irritated bronchial tubes for as long as a few months may inspire asthmatic conditions in some patients.

In addition, if one starts coughing mucus tinged with blood, one should see a physician. In rare cases, physicians may conduct tests to see whether the cause of the bloody sputum is a serious condition such as tuberculosis or lung cancer.

Lower respiratory tract infection (LRTI), while often used as a synonym for pneumonia, can also be applied to other types of infection including lung abscess and acute bronchitis. Symptoms include shortness of breath, weakness, fever, coughing and fatigue.

There are a number of symptoms that are characteristic of lower respiratory tract infections. The two most common are bronchitis and edema. Influenza affects both the upper and lower respiratory tracts.

Antibiotics are the first line treatment for pneumonia; however, they are not effective or indicated for parasitic or viral infections. Acute bronchitis typically resolves on its own with time.

In 2015 there were about 291 million cases. These resulted in 2.74 million deaths down from 3.4 million deaths in 1990. This was 4.8% of all deaths in 2013.

Bronchitis describes the swelling or inflammation of the bronchial tubes. Additionally, bronchitis is described as either acute or chronic depending on its presentation and is also further described by the causative agent. Acute bronchitis can be defined as acute bacterial or viral infection of the larger airways in healthy patients with no history of recurrent disease. It affects over 40 adults per 1000 each year and consists of transient inflammation of the major bronchi and trachea. Most often it is caused by viral infection and hence antibiotic therapy is not indicated in immunocompetent individuals. Viral bronchitis can sometimes be treated using antiviral medications depending on the virus causing the infection, and medications such as anti-inflammatory drugs and expectorants can help mitigate the symptoms. Treatment of acute bronchitis with antibiotics is common but controversial as their use has only moderate benefit weighted against potential side effects (nausea and vomiting), increased resistance, and cost of treatment in a self-limiting condition. Beta2 agonists are sometimes used to relieve the cough associated with acute bronchitis. In a recent systematic review it was found there was no evidence to support their use.

Chronic bronchitis is defined as a productive cough that lasts for three months or more per year for at least two years. Most people with chronic bronchitis have chronic obstructive pulmonary disease (COPD). Protracted bacterial bronchitis is defined as a chronic productive cough with a positive bronchoalveolar lavage that resolves with antibiotics. Symptoms of chronic bronchitis may include wheezing and shortness of breath, especially upon exertion and low oxygen saturations. The cough is often worse soon after awakening and the sputum produced may have a yellow or green color and may be streaked with specks of blood.

A URI may be classified by the area inflamed.

Rhinitis affects the nasal mucosa, while rhinosinusitis or sinusitis affects the nose and paranasal sinuses, including frontal, ethmoid, maxillary, and sphenoid sinuses. Nasopharyngitis (rhinopharyngitis or the common cold) affects the nares, pharynx, hypopharynx, uvula, and tonsils generally. Without involving the nose, pharyngitis inflames the pharynx, hypopharynx, uvula, and tonsils. Similarly, epiglottitis (supraglottitis) inflames the superior portion of the larynx and supraglottic area; laryngitis is in the larynx; laryngotracheitis is in the larynx, trachea, and subglottic area; and tracheitis is in the trachea and subglottic area.

In uncomplicated colds, cough and nasal discharge may persist for 14 days or more even after other symptoms have resolved.

Acute upper respiratory tract infections include rhinitis, pharyngitis/tonsillitis and laryngitis often referred to as a common cold, and their complications: sinusitis, ear infection and sometimes bronchitis (though bronchi are generally classified as part of the lower respiratory tract.) Symptoms of URTIs commonly include cough, sore throat, runny nose, nasal congestion, headache, low-grade fever, facial pressure and sneezing.

Symptoms of rhinovirus in children usually begin 1–3 days after exposure. The illness usually lasts 7–10 more days.

Color or consistency changes in mucous discharge to yellow, thick, or green are the natural course of viral upper respiratory tract infection and not an indication for antibiotics.

Group A beta hemolytic streptococcal pharyngitis/tonsillitis (strep throat) typically presents with a sudden onset of sore throat, pain with swallowing and fever. Strep throat does not usually cause runny nose, voice changes, or cough.

Pain and pressure of the ear caused by a middle ear infection (otitis media) and the reddening of the eye caused by viral conjunctivitis are often associated with upper respiratory infections.

Pneumonia occurs in a variety of situations and treatment must vary according to the situation. It is classified as either community or hospital acquired depending on where the patient contracted the infection. It is life-threatening in the elderly or those who are immunocompromised. The most common treatment is antibiotics and these vary in their adverse effects and their effectiveness. Pneumonia is also the leading cause of death in children less than five years of age in low income countries. The most common cause of pneumonia is pneumococcal bacteria, "Streptococcus pneumoniae" accounts for 2/3 of bacteremic pneumonias. This is a dangerous type of lung infection with a mortality rate of around 25%.

For optimal management of a pneumonia patient, the following must be assessed: pneumonia severity (including treatment location, e.g., home, hospital or intensive care), identification of causative organism, analgesia of chest pain, the need for supplemental oxygen, physiotherapy, hydration, bronchodilators and possible complications of emphysema or lung abscess.

"Streptococcus pneumoniae" () is the most common bacterial cause of pneumonia in all age groups except newborn infants. "Streptococcus pneumoniae" is a Gram-positive bacterium that often lives in the throat of people who do not have pneumonia.

Other important Gram-positive causes of pneumonia are "Staphylococcus aureus" () and "Bacillus anthracis".

Gram-negative bacteria are seen less frequently: "Haemophilus influenzae" (), "Klebsiella pneumoniae" (), "Escherichia coli" (), "Pseudomonas aeruginosa" (), "Bordetella pertussis", and "Moraxella catarrhalis" are the most common.

These bacteria often live in the gut and enter the lungs when contents of the gut (such as vomit or faeces) are inhaled.

Cat flu is the common name for a feline upper respiratory tract disease. While feline upper respiratory disease can be caused by several different pathogens, there are few symptoms that they have in common.

While Avian Flu can also infect cats, Cat flu is generally a misnomer, since it usually does not refer to an infection by an influenza virus. Instead, it is a syndrome, a term referring to the fact that patients display a number of symptoms that can be caused by one or more of the following infectious agents (pathogens):

1. Feline herpes virus causing feline viral rhinotracheitis (cat common cold, this is the disease that is closely similar to cat flu)

2. Feline calicivirus—(cat respiratory disease)

3. "Bordetella bronchiseptica"—(cat kennel cough)

4. "Chlamydophila felis"—(chlamydia)

In South Africa the term cat flu is also used to refer to Canine Parvo Virus. This is misleading, as transmission of the Canine Parvo Virus rarely involves cats.

Symptoms are similar to tuberculosis (TB), and include fever, fatigue, and weight loss. Pulmonary involvement is similar to TB, while diarrhea and abdominal pain are associated with gastrointestinal involvement.

Some people with bronchiectasis may have a cough productive of frequent green/yellow mucus (sputum), up to 240 ml (8 oz) daily. Bronchiectasis may also present with coughing up blood (hemoptysis) in the absence of sputum, called "dry bronchiectasis". Sputum production may also occur without coloration. People with bronchiectasis may have bad breath indicative of active infection. Frequent bronchial infections and breathlessness are two possible indicators of bronchiectasis.

Crepitations and expiratory rhonchi may be heard on auscultation. Nail clubbing is rare.

Feline viral rhinotracheitis (FVR) is an upper respiratory or pulmonary infection of cats caused by "feline herpesvirus 1", of the family "Herpesviridae". It is also commonly referred to as feline influenza, feline coryza, and feline pneumonia but, as these terms describe other very distinct collections of respiratory symptoms, they are misnomers for the condition. Viral respiratory diseases in cats can be serious, especially in catteries and kennels. Causing one-half of the respiratory diseases in cats, FVR is the most important of these diseases and is found worldwide. The other important cause of feline respiratory disease is "feline calicivirus".

FVR is very contagious and can cause severe disease, including death from pneumonia in young kittens. It can cause flat-chested kitten syndrome, but most evidence for this is anecdotal. All members of the "Felidae" family are susceptible to FVR; in fact, FHV-1 has caused a fatal encephalitis in lions in Germany.

Bronchiectasis has both congenital and acquired causes, with the latter more frequent. Cystic fibrosis is a cause in up to half of cases. The cause in 10-50% of those without cystic fibrosis is unknown; bronchiectasis without CF is known as non-CF bronchiectasis (NCBE).

Initial signs of FVR include coughing, sneezing, nasal discharge, conjunctivitis, and sometimes fever (up to 106) and loss of appetite. These usually resolve within four to seven days, but secondary bacterial infections can cause the persistence of clinical signs for weeks. Frontal sinusitis and empyema can also result.

FHV-1 also has a predilection for corneal epithelium, resulting in corneal ulcers, often pinpoint or dendritic in shape. Other ocular signs of FHV-1 infection include conjunctivitis, keratitis, keratoconjunctivitis sicca (decreased tear production), and corneal sequestra. Infection of the nasolacrimal duct can result in chronic epiphora (excess tearing). Ulcerative skin disease can also result from FHV-1 infection. FHV-1 can also cause abortion in pregnant queens, usually at the sixth week of gestation, although this may be due to systemic effects of the infection rather than the virus directly.

In chronic nasal and sinus disease of cats, FHV-1 may play more of an initiating role than an ongoing cause. Infection at an early age may permanently damage nasal and sinus tissue, causing a disruption of ciliary clearance of mucus and bacteria, and predispose these cats to chronic bacterial infections.

Bovine viral diarrhea (BVD) or bovine viral diarrhoea (UK English), and previously referred to as bovine virus diarrhoea (BVD), is a significant economic disease of cattle that is endemic in the majority of countries throughout the world. The causative agent, bovine viral diarrhea virus (BVDV), is a member of the "Pestivirus" genus of the family Flaviviridae.

BVD infection results in a wide variety of clinical signs, due to its immunosuppressive effects, as well as having a direct effect on respiratory disease and fertility. In addition, BVD infection of a susceptible dam during a certain period of gestation can result in the production of a persistently infected (PI) fetus.

PI animals recognise intra-cellular BVD viral particles as ‘self’ and shed virus in large quantities throughout life; they represent the cornerstone of the success of BVD as a disease.

BVDV infection has a wide manifestation of clinical signs including fertility issues, milk drop, pyrexia, diarrhoea and fetal infection. Occasionally, a severe acute form of BVD may occur. These outbreaks are characterized by thrombocytopenia with high morbidity and mortality. However, clinical signs are frequently mild and infection insidious, recognised only by BVDV’s immunosuppressive effects perpetuating other circulating infectious diseases (particularly scours and pneumonias).

"Mycobacterium avium-intracellulare" infection (MAI) is an atypical mycobacterial infection, i.e. one with nontuberculous mycobacteria or NTM, caused by "Mycobacterium avium" complex ("MAC"), which is made of three mycobacteria species, "M. avium", "M. intracellulare", and "M. chimaera". This infection causes respiratory illness in birds, pigs, and humans, especially in immunocompromised people. In the later stages of AIDS it can be very severe. It usually first presents as a persistent cough. It is typically treated with a series of three antibiotics for a period of at least six months.

"M. avium", "M. intracellulare", and "M. chimaera" are each saprotrophic organisms present in soil and water; entry into hosts is usually via the gastrointestinal tract, but also can be via the lungs.

MAC infections can cause fevers, diarrhea, malabsorption, as well as loss of appetite and weight loss, and can disseminate to the bone marrow. Therapy for MAI is typically resistant to standard mycobacterial therapies.

Aujeszky's disease, usually called pseudorabies in the United States, is a viral disease in swine that has been endemic in most parts of the world. It is caused by "Suid herpesvirus 1" (SuHV1). Aujeszky's disease is considered to be the most economically important viral disease of swine in areas where hog cholera has been eradicated. Other mammals, such as humans, cattle, sheep, goats, cats, dogs, and raccoons, are also susceptible. The disease is usually fatal in these animal species bar humans.

The term "pseudorabies" is found inappropriate by many people, as SuHV1 is a herpesvirus and not related to the rabies virus.

Research on SuHV1 in pigs has pioneered animal disease control with genetically modified vaccines. SuHV1 is now used in model studies of basic processes during lytic herpesvirus infection, and for unravelling molecular mechanisms of herpesvirus neurotropism.

Common signs and symptoms include:

- sore throat

- red, swollen tonsils

- pain when swallowing

- high temperature (fever)

- headache

- tiredness

- chills

- a general sense of feeling unwell (malaise)

- white pus-filled spots on the tonsils

- swollen lymph nodes (glands) in the neck

- pain in the ears or neck

- weight loss

- difficulty ingesting and swallowing meal/liquid intake

- difficulty sleeping

Less common symptoms include:

- nausea

- fatigue

- stomach ache

- vomiting

- furry tongue

- bad breath (halitosis)

- voice changes

- difficulty opening the mouth (trismus)

- loss of appetite

- Anxiety/fear of choking

In cases of acute tonsillitis, the surface of the tonsil may be bright red and with visible white areas or streaks of pus.

Tonsilloliths occur in up to 10% of the population frequently due to episodes of tonsillitis.