The mortality rate of the virus largely depends on the immune status of the infected dogs. Puppies experience the highest mortality rate, where complications such as pneumonia and encephalitis are more common. In older dogs that develop distemper encephalomyelitis, vestibular disease may present. Around 15% of canine inflammatory central nervous system diseases are a result of CDV.

The prevalence of canine distemper in the community has decreased dramatically due to the availability of vaccinations. However, the disease continues to spread among unvaccinated populations, such as those in animal shelters and pet stores. This provides a great threat to both the rural and urban communities throughout the United States, affecting both shelter and domestic canines. Despite the effectiveness of the vaccination, outbreaks of this disease continue to occur nationally. In April 2011, the Arizona Humane Society released a valley-wide pet health alert throughout Phoenix, Arizona.

Outbreaks of canine distemper continue to occur throughout the United States and elsewhere, and are caused by many factors. These factors include the overpopulation of dogs and the irresponsibility of pet owners. The overpopulation of dogs is a national problem that organizations such as the Humane Society and ASPCA face every day. This problem is even greater within areas such as Arizona, owing to the vast amount of rural land. An unaccountable number of strays that lack vaccinations reside in these areas and are therefore more susceptible to diseases such as canine distemper. These strays act as a host for the virus, spreading it throughout the surrounding area, including urban areas. Puppies and dogs that have not received their shots can then be infected if in a place where many dogs interact, such as a dog park.

Canine influenza (dog flu) is influenza occurring in canine animals. Canine influenza is caused by varieties of influenzavirus A, such as equine influenza virus H3N8, which in 2004 was discovered to cause disease in dogs. Because of the lack of previous exposure to this virus, dogs have no natural immunity to it. Therefore, the disease is rapidly transmitted between individual dogs. Canine influenza may be endemic in some regional dog populations of the United States. It is a disease with a high morbidity (incidence of symptoms) but a low incidence of death.

A newer form was identified in Asia during the 2000s and has since caused outbreaks in the US as well. It is a mutation of H3N2 that adapted from its avian influenza origins. Vaccines have been developed for both strains.

Dogs will typically recover from kennel cough within a few weeks. However, secondary infections could lead to complications that could do more harm than the disease itself. Several opportunistic invaders have been recovered from the respiratory tracts of dogs with kennel cough, including Streptococcus, Pasteurella, Pseudomonas, and various coliforms. These bacteria have the potential to cause pneumonia or sepsis, which drastically increase the severity of the disease. These complications are evident in thoracic radiographic examinations. Findings will be mild in animals affected only by kennel cough, while those with complications may have evidence of segmental atelectasis and other severe side effects.

Influenza A viruses are enveloped, negative sense, single-stranded RNA viruses. Genome analysis has shown that H3N8 was transferred from horses to dogs and then adapted to dogs through point mutations in the genes. The incubation period is two to five days, and viral shedding may occur for seven to ten days following the onset of symptoms. It does not induce a persistent carrier state.

Viral infections such as canine parainfluenza or canine coronavirus are only shed for roughly 1 week following recovery; however, respiratory infections involving "Bordetella bronchiseptica" can be transmissible for several weeks longer. While there was early evidence to suggest that "B. bronchiseptica" could be shed for many months post-infection, a more recent report places detectable nasal and pharyngeal levels of "B. bronchiseptica" in 45.6% of all clinically healthy dogs. This has potentially expanded the vector from currently or recently infected dogs to half the dog population as carriers. To put the relative levels of shedding bacteria into perspective, a study analyzing the shedding kinetics of "B. bronchiseptica" presents the highest levels of bacterial shedding one week post-exposure, with an order of magnitude decrease in shedding observed every week. This projection places negligible levels of shedding to be expected 6 weeks post-exposure (or ~5 weeks post-onset of symptoms). Dogs which had been administered intranasal vaccine 4 weeks prior to virulent "B. bronchiseptica" challenge displayed little to no bacterial shedding within 3 weeks of exposure to the virulent strain.

Globally, 59,000 people die from rabies each year. This is the equivalent of one person dying every nine minutes, with half of the people who die from rabies being under the age of 15. The Pan American Health Organization (PAHO) and the Pan American Center of foot-and-mouth disease (PANAFTOSA) led a mission to eliminate dog-mediated rabies in the American region by 2015. These organizations are cognizant of the regional control of rabies. The PAHO and PANAFTOSA visited Haiti in early December, 2013, and the objectives of the mission were to assess the status of Haiti’s rabies program as delivered by the Haitian Ministry of Agriculture, Natural Resources and Rural Development (MARNDR) and the Ministry of Health (MSPP). The mission was to seek opportunities for collaboration between Haiti, Brazil, and the Centers for Disease Control and Prevention (CDC) in Haiti.

Even in 2017, rabies in Haiti is still identified as a national problem, even with PEP proposed.

In Haiti, few cases of human rabies are reported to health authorities. In 2016, a report of a woman who had been exposed to rabies three months prior and was showing symptoms went to the hospital where no treatment was administered to her. Even after being reported to both the CDC and the national Department of Epidemiology and Laboratory Research (DELR), as required by Haiti's surveillance program, the woman ended up passing away. This goes to show the lack of communication and effectiveness in caring for human subjects in Haiti, and the continued focus is on eliminating dog-mediated rabies altogether.

Human diploid cell culture rabies vaccine (HDCV) and purified chick embryo cell culture rabies vaccine (PCEC) are used to treat post-exposure immunization against a human rabies infection. Recommendations for treatment are given by governmental health care organizations and in health literature. Health care providers are encouraged to administer a regimen of four 1-mL doses of HDCV or PCEC vaccines. According to the CDC, these injections should be administered intramuscularly to persons who have not yet been vaccinated for rabies.

For those who are unvaccinated, the first of four doses is administered immediately after exposure to the rabies virus. Additional doses are given three, seven, and fourteen days after the first vaccination. Exposure usually means a bite from a rabid animal.

At an individual patient level, post-exposure prophylaxis (PEP) consists of local treatment of the wound, vaccination, and administration of immunoglobulin, if necessary [3]. At the program level, several components are critical, including: adequate and prompt recognition of the need for PEP by the public, if exposed, and by health officials, prompt and sufficient availability of high-quality PEP, and adequate follow-up of PEP use. Health officials' awareness of the need for PEP after a dog bite can only be achieved if the exposure is attended to immediately and communicated effectively.

Ehrlichiosis is a nationally notifiable disease in the United States. There have been cases reported in every month of the year, but most cases are reported during April–September. These months are also the peak months for tick activity in the United States.

From 2008-2012, the average yearly incidence of ehrlichiosis was 3.2 cases per million persons. This is more than twice the estimated incidence for the years 2000-2007. The incidence rate increases with age, with the ages of 60–69 years being the highest age-specific years. Children of less than 10 years and adults aged 70 years and older, have the highest case-fatality rates. There is a documented higher risk of death among persons who are immunosuppressed.

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.

Doxycycline and minocycline are the medications of choice. For people allergic to antibiotics of the tetracycline class, rifampin is an alternative. Early clinical experience suggested that chloramphenicol may also be effective, however, in vitro susceptibility testing revealed resistance.

Aleutian disease, also known as mink plasmacytosis, is a disease which causes spontaneous abortion and death in minks and ferrets. It is caused by "Carnivore amdoparvovirus 1" (also known as "Aleution diease virus", ADV), a highly contagious parvovirus in the genus "Amdoparvovirus".

The virus has been found as a natural infection in the "Mustelidae" family within mink, ferrets, otters, polecats, stone and pine martens and within other varying carnivores such as skunks, genets, foxes and raccoons. This is most commonly explained as because they all share resources and habitats.

Possible complications include the horse becoming a chronic carrier of the disease, asphyxia due to enlarged lymph nodes compressing the larynx or windpipe, bastard strangles (spreading to other areas of the body), pneumonia, guttural pouch filled with pus, abscesses, purpura haemorrhagica, and heart disease. The average length for the course of this disease is 23 days.

Both intramuscular and intranasal vaccines are available. Isolation of new horses for 4 to 6 weeks, immediate isolation of infected horses, and disinfection of stalls, water buckets, feed troughs, and other equipment will help prevent the spread of strangles. As with any contagious disease, handwashing is a simple and effective tool.

Tick control is the most effective method of prevention, but tetracycline at a lower dose can be given daily for 200 days during the tick season in endemic regions.

The prognosis is good for dogs with acute ehrlichiosis. For dogs that have reached the chronic stage of the disease, the prognosis is guarded. When bone marrow suppression occurs and there are low levels of blood cells, the animal may not respond to treatment.

Only 8% of infected horses have this form of pigeon fever, however, it has a 30-40% fatality rate. Organs that are commonly affected are the liver, spleen, and lungs. For a successful recovery, long-term antimicrobial therapy is essential.

A lethal infection in mink, the Aleutian disease virus lies dormant in ferrets until stress or injury allows it to surface. While the parvovirus itself causes little or no harm to the ferret host, the large number of antibodies produced in response to the presence of the virus results in a systemic vasculitis, resulting in eventual renal failure, bone marrow suppression and death.

The symptoms are chronic, progressive weight loss, lethargy, splenomegaly (enlarged spleen), anemia, rear leg weakness, seizures and black tarry stool. Additional symptoms include poor reproduction and/or oral bleeding/gastrointestinal bleeding. Lesions can also be found within the pelt depending on the severity of the disease. This virus can unfortunately reduce fitness of wild mink especially, by disturbing both the productivity within adult females and the overall survivor rates of both juveniles and adults. Likewise, in the mink kits that survive, it infects the alveolar cells and ultimately causes respiratory distress, possibly leading to death.

Once symptoms show themselves, the disease progresses rapidly, usually to death within a few months.

The coronavirus which causes ECE has a counterpart strain that has more systemic effects with a higher mortality rate. This systemic syndrome has been compared to Feline infectious peritonitis in cats.

Traditionally, canine transmission is directly from sandfly to dog. Cases in the United States have proven "L. infantum" transmission from dog to dog by direct contamination with blood and secretions, as well as transplacentally from an infected bitch to her pups. This mode of transmission seems to be unique to the "L. infantum" Mon1 strain found in the United States. Although "in utero" transmission is likely the predominant method of disease spread amount the "L. infantum" Mon1 strain, it is still a viable parasite (has not lost virulence factors associated with sandfly-uptake) which can be transmitted via sandfly bite. A Brazilian study of 63 puppies from 18 "L. donovani"-infected parents found no evidence of congential or transplacental infection.

Epizootic catarrhal enteritis (ECE) is a viral disease that first appeared in the northeastern US in 1994, is an inflammation of the mucous membranes in the intestine. The condition manifests itself as severe diarrhea (often of a bright green color), loss of appetite, and severe weight loss. The virus can be passed via fluids and indirectly between humans. Although it was often fatal when first discovered, ECE is less of a threat today.

Numerous strains and subgenus strains of "Leishmania" exist; with sandfly genome projects still underway, strains are still being discovered.

In the Old World, leishmaniasis transmitted by sandflies of the genus "Phlebotomus" documented in dogs are:

- "L. donovani" in Sri Lanka

- "L. infantum" (began appearing dogs in the United States in 2000)

New World leishmaniasis strains are spread by "Lutzomyia"; however, research speculates the North American sandfly could be capable of spreading, but this is to date unconfirmed. Dogs are known resorvoirs of "L. infantum", and the spread of disease from dog to dog has been confirmed in the United States.

- Suspected causes of canine visceral leishmaniasis are geographic variants of the "Leishmania donovani" complex, including "L. infantum, L. chagasi" and "L. donovani".

The Mexicana ("L. mexicana, L. amazonensis, L. venezuelensis", and "L. pifanoi") and Viannia ("L. braziliensis, L. guyanensis, L. panamensis" and "L. peruviana") strains are not commonly found in dogs. Subgenus Viannia strains are found only in Central and South America, all of which cause leishmaniasis in humans.

The disease can occur in horses of any age, breed or gender. In the US, it occurs throughout the country and at any time of year. The disease was traditionally thought to occur mainly in dry, arid regions, but from at least 2005, its range has been increasing into areas where it was not previously seen, such as the Midwestern US, and Western Canada. Environmental risk factors include over 7 days of a weekly average land surface temperatures above 35 °C, and drier soils; these factors were implicated in an outbreak in Kansas in 2012.

Death rates during outbreaks were usually extremely high, approaching 100% in immunologically naïve populations. The disease was mainly spread by direct contact and by drinking contaminated water, although it could also be transmitted by air.

Initial symptoms include fever, loss of appetite, and nasal and eye discharges. Subsequently, irregular erosions appear in the mouth, the lining of the nose, and the genital tract. Acute diarrhea, preceded by constipation, is also a common feature. Most animals die six to twelve days after the onset of these clinical signs.

Rinderpest was one of more than a dozen agents the United States researched as potential biological weapons before terminating its biological weapons program.

Rinderpest is of concern as a biological weapon for the following reasons:

- The disease has high rates of morbidity and mortality.

- The disease is highly communicable and spreads rapidly once introduced into nonimmune herds.

- Cattle herds are no longer immunized against RPV and therefore are susceptible to infection.

Rinderpest was also considered as a biological weapon in the United Kingdom's program during World War II.