A serious outbreak of equine herpesvirus type 1 (EHV-1), an infectious viral disease, is currently spreading among horse populations in Europe. This outbreak was first detected in Valencia, Spain, in February 2021 during a month-long equestrian competition. Multiple dozens of horses contracted an initially unknown disease, with up to 20 horses being treated daily for a variety of symptoms. Some of these symptoms were unusually severe. Many horses showed drastic behavioral changes, pointing to neurological damage, whereas other animals experienced respiratory distress, blood clots, or general malaise. Before the origin of the disease could be identified and before the vast majority of horses could be quarantined, the Spanish competition ended and more than 600 horses returned to their home stables located throughout Europe. Once the pathogen was identified as EHV-1, the Fédération Équestre Internationale (International Federation for Equestrian Sports) postponed or cancelled all European equine events through May 2021. Concerns over transmission of this virus may extend the pause in equine events throughout Europe beyond this spring. See also: Agricultural science (animal); Animal virus; Herpes; Horse production; Infectious disease; Virus

Members of the genus Morbillivirus (family Paramyxoviridae), collectively known as morbilliviruses, are RNA-containing viruses. They cause a number of important diseases, including measles in humans, canine distemper in dogs, and rinderpest in bovines. Since July 2013, a serious morbillivirus outbreak has occurred among bottlenose dolphins (Tursiops truncatus) predominantly along the eastern coast of the United States (from New York to Florida), resulting in the strandings and deaths of almost 1500 of these marine creatures. This recent cetacean morbillivirus epidemic is larger and more significant than a similar morbillivirus outbreak that occurred in 1987–1988, during which 742 bottlenose dolphins died. See also: Animal virus; Canine distemper; Cetacea; Disease; Emerging diseases in marine mammals; Measles; Paramyxovirus; Ribonucleic acid (RNA); Rinderpest; Virus; Virus classification

Influenza is a viral disease that affects numerous animals, including birds, pigs, horses, and humans. It also can affect dogs, and epidemiologists are increasingly concerned about the potential transmission of the influenza virus from these animals to humans. Canine influenza (dog flu) is caused by specific type A strains of the influenza virus. It is a contagious respiratory illness in dogs that resembles kennel cough. Although canine influenza first appeared in greyhound dogs, the respiratory illness has been observed in a variety of breeds, and all dogs are considered to be at risk of infection. However, no cases of transmission of the influenza virus from dogs to humans have been identified. Still, scientists are aware that public health conditions could deteriorate rapidly, possibly leading to a pandemic (an epidemic occurring over a widespread geographic area), if this type of transmission were to take place. See also: Animal virus; Canine influenza; Dogs; Epidemic; Infectious disease; Influenza; Kennel cough; Public health; Virus

Persistent changes in the Earth's climate that have been occurring primarily as a result of human-caused greenhouse-gas emissions since the mid-twentieth century have led to significant increases in infectious diseases in wildlife, both in terms of the sheer numbers of affected animal species and with regard to the severity of disease. In particular, pathogenic bacteria, fungi, viruses, and parasitic worms (helminths) are the predominant organisms finding opportunities to infect novel or additional wildlife hosts in new habitats as climate change gains traction across the globe. Scientists have now correlated the emergence of infectious disease in wildlife populations to instances of both increasing and decreasing climatic temperatures, as well as shifts in precipitation. The risks to wildlife from infectious diseases also depend on the specific pathogenic agent and the degree to which the host animal can adapt to pathogenic threats and concomitant shifts in climate. Disease risks are estimated to be greatest among cold-blooded (ectothermic) and nonmigratory host species, such as amphibians, which have more difficulty adapting to climatic shifts. However, researchers also predict that emergent infectious diseases will become highly prevalent among numerous warm-blooded (endothermic) animals, such as mammals, as parasites move to higher altitudes and more northern latitudes in warming environments as a result of continuing global climate change. See also: Acanthocephala; Amphibia; Bacteria; Climatology; Ecosystem; Fungi; Global climate change; Infectious disease; Mammalia; Parasitology; Pathogen; Virus