A number of liver function tests (LFTs) are available to test the proper function of the liver. These test for the presence of enzymes in blood that are normally most abundant in liver tissue, metabolites or products. serum proteins, serum albumin, serum globulin,

alanine transaminase, aspartate transaminase, prothrombin time, partial thromboplastin time.

Imaging tests such as transient elastography, ultrasound and magnetic resonance imaging can be used to examine the liver tissue and the bile ducts. Liver biopsy can be performed to examine liver tissue to distinguish between various conditions; tests such as elastography may reduce the need for biopsy in some situations.

Anti-viral medications are available to treat infections such as hepatitis B. Other conditions may be managed by slowing down disease progression, for example:

- By using steroid-based drugs in autoimmune hepatitis.

- Regularly removing a quantity of blood from a vein (venesection) in the iron overload condition, hemochromatosis.

- Wilson’s disease, a condition where copper builds up in the body, can be managed with drugs which bind copper allowing it to be passed from your body in urine.

- In cholestatic liver disease, (where the flow of bile is affected due to cystic fibrosis) a medication called ursodeoxycholic acid (URSO, also referred to as UDCA) may be given.

The differential diagnosis in a case of suspected human rabies may initially include any cause of encephalitis, in particular infection with viruses such as herpesviruses, enteroviruses, and arboviruses such as West Nile virus. The most important viruses to rule out are herpes simplex virus type one, varicella zoster virus, and (less commonly) enteroviruses, including coxsackieviruses, echoviruses, polioviruses, and human enteroviruses 68 to 71.

New causes of viral encephalitis are also possible, as was evidenced by the 1999 outbreak in Malaysia of 300 cases of encephalitis with a mortality rate of 40% caused by Nipah virus, a newly recognized paramyxovirus. Likewise, well-known viruses may be introduced into new locales, as is illustrated by the outbreak of encephalitis due to West Nile virus in the eastern United States. Epidemiologic factors, such as season, geographic location, and the patient's age, travel history, and possible exposure to bites, rodents, and ticks, may help direct the diagnosis.

Rabies can be difficult to diagnose, because, in the early stages, it is easily confused with other diseases or with aggressiveness. The reference method for diagnosing rabies is the fluorescent antibody test (FAT), an immunohistochemistry procedure, which is recommended by the World Health Organization (WHO). The FAT relies on the ability of a detector molecule (usually fluorescein isothiocyanate) coupled with a rabies-specific antibody, forming a conjugate, to bind to and allow the visualisation of rabies antigen using fluorescent microscopy techniques. Microscopic analysis of samples is the only direct method that allows for the identification of rabies virus-specific antigen in a short time and at a reduced cost, irrespective of geographical origin and status of the host. It has to be regarded as the first step in diagnostic procedures for all laboratories. Autolysed samples can, however, reduce the sensitivity and specificity of the FAT. The RT PCR assays proved to be a sensitive and specific tool for routine diagnostic purposes, particularly in decomposed samples or archival specimens. The diagnosis can be reliably made from brain samples taken after death. The diagnosis can also be made from saliva, urine, and cerebrospinal fluid samples, but this is not as sensitive and reliable as brain samples. Cerebral inclusion bodies called Negri bodies are 100% diagnostic for rabies infection but are found in only about 80% of cases. If possible, the animal from which the bite was received should also be examined for rabies.

Some light microscopy techniques may also be used to diagnose rabies at a tenth of the cost of traditional fluorescence microscopy techniques, allowing identification of the disease in less-developed countries.

Currently, there is no proven, safe treatment for monkeypox. The people who have been infected can be vaccinated up to 14 days after exposure.

The above signs, especially fever, respiratory signs, neurological signs, and thickened footpads occurring in unvaccinated dogs strongly indicate canine distemper. However, several febrile diseases match many of the signs of the disease and only recently has distinguishing between canine hepatitis, herpes virus, parainfluenza and leptospirosis been possible. Thus, finding the virus by various methods in the dog's conjunctival cells or foot pads gives a definitive diagnosis. In older dogs that develop distemper encephalomyelitis, diagnosis may be more difficult, since many of these dogs have an adequate vaccination history.

An additional test to confirm distemper is a brush border slide of the bladder transitional epithelium of the inside lining from the bladder, stained with Dif-Quick. These infected cells have inclusions which stain a carmine red color, found in the paranuclear cytoplasm readability. About 90% of the bladder cells will be positive for inclusions in the early stages of distemper.

A number of vaccines against canine distemper exist for dogs (ATCvet code: and combinations) and domestic ferrets (), which in many jurisdictions are mandatory for pets. Infected animals should be quarantined from other dogs for several months owing to the length of time the animal may shed the virus. The virus is destroyed in the environment by routine cleaning with disinfectants, detergents, or drying. It does not survive in the environment for more than a few hours at room temperature (20–25 °C), but can survive for a few weeks in shady environments at temperatures slightly above freezing. It, along with other labile viruses, can also persist longer in serum and tissue debris.

Despite extensive vaccination in many regions, it remains a major disease of dogs.

To prevent canine distemper, puppies should begin vaccination at six to eight weeks of age and then continue getting the “booster shot” every two to four weeks until they are 16 weeks of age. Without the full series of shots, the vaccination will not provide protection against the virus. Since puppies are typically sold at the age of eight to ten weeks, they typically receive the first shot while still with their breeder, but the new owner often does not finish the series. These dogs are not protected against the virus and so are susceptible to canine distemper infection, continuing the downward spiral that leads to outbreaks throughout the country.

Vaccination against smallpox is assumed to provide protection against human monkeypox infection considering they are closely related viruses and the vaccine protects animals from experimental lethal monkeypox challenge. This has not been conclusively demonstrated in humans because routine smallpox vaccination was discontinued following the apparent eradication of smallpox and due to safety concerns with the vaccine.

Smallpox vaccine has been reported to reduce the risk of monkeypox among previously vaccinated persons in Africa. The decrease in immunity to poxviruses in exposed populations is a factor in the prevalence of monkeypox. It is attributed both to waning cross-protective immunity among those vaccinated before 1980 when mass smallpox vaccinations were discontinued, and to the gradually increasing proportion of unvaccinated individuals. The United States Centers for Disease Control and Prevention (CDC) recommends that persons investigating monkeypox outbreaks and involved in caring for infected individuals or animals should receive a smallpox vaccination to protect against monkeypox. Persons who have had close or intimate contact with individuals or animals confirmed to have monkeypox should also be vaccinated.

CDC does not recommend preexposure vaccination for unexposed veterinarians, veterinary staff, or animal control officers, unless such persons are involved in field investigations.

Diagnosis is based on symptoms and upon finding an embedded tick, usually on the scalp.

In the absence of a tick, the differential diagnosis includes Guillain–Barré syndrome. Early signs of tick poisoning could be a change of an animals' ‘voice’, weakness in the back legs or vomiting.

Removal of the embedded tick usually results in resolution of symptoms within several hours to days. If the tick is not removed, the toxin can be fatal, with reported mortality rates of 10–12 percent, usually due to respiratory paralysis. The tick is best removed by grasping the tick as close to the skin as possible and pulling in a firm steady manner.

Unlike the other species of ticks, the toxin of Ixodes holocyclus (Australian Paralysis Tick) will not resolve itself and will be fatal if medical assistance is not immediately sought after pulling the tick off of the animal. Contrary to popular belief, if the head detaches from the body while being pulled off, leaving the head will not inject more venom. The head may cause a skin irritation but it will not inject any more venom. Once the tick is removed, place it in a clear bag [preferably ziplock] so the vet can identify it.

Water and food can worsen the results of the animal as the venom can prevent the animal from swallowing properly. If you find an Australian Paralysis Tick on your animal, immediately remove the tick and seek veterinary assistance even if you do not think the tick has been on the animal long enough to inject venom.

Outbreaks of zoonoses have been traced to human interaction with and exposure to animals at fairs, petting zoos, and other settings. In 2005, the Centers for Disease Control and Prevention (CDC) issued an updated list of recommendations for preventing zoonosis transmission in public settings. The recommendations, developed in conjunction with the National Association of State Public Health Veterinarians, include educational responsibilities of venue operators, limiting public and animal contact, and animal care and management.

In pet rabbits, myxomatosis can be misdiagnosed as pasteurellosis, a bacterial infection which can be treated with antibiotics. By contrast, there is no treatment for rabbits suffering from myxomatosis, other than palliative care to ease the suffering of individual animals, and the treatment of secondary and opportunistic infections, in the hopes the treated animal will survive. In practice, the owner is often urged to euthanize the animal to end its suffering.

Contact with farm animals can lead to disease in farmers or others that come into contact with infected animals. Glanders primarily affects those who work closely with horses and donkeys. Close contact with cattle can lead to cutaneous anthrax infection, whereas inhalation anthrax infection is more common for workers in slaughterhouses, tanneries and wool mills. Close contact with sheep who have recently given birth can lead to clamydiosis, or enzootic abortion, in pregnant women, as well as an increased risk of Q fever, toxoplasmosis, and listeriosis in pregnant or the otherwise immunocompromised. Echinococcosis is caused by a tapeworm which can be spread from infected sheep by food or water contaminated with feces or wool. Bird flu is common in chickens. While rare in humans, the main public health worry is that a strain of bird flu will recombine with a human flu virus and cause a pandemic like the 1918 Spanish flu. In 2017, free range chickens in the UK were temporarily ordered to remain inside due to the threat of bird flu. Cattle are an important reservoir of cryptosporidiosis and mainly affects the immunocompromised.

The bacteria invade the lacrimal glands of the eye, causing keratitis, uveitis, and corneal ulceration. Cattle show signs of pain, increased lacrimation, excessive blinking, and conjunctivitis. More severe cases may show systemic signs such as anorexia and weight loss. Chronic untreated cases can become blind. Diagnosis is usually based on the clinical signs, but the bacteria can be cultured from lacrimal swabs, or visualised on smears of lacrimal secretions.

Shade, insect repellent-impregnated ear tags, and lower stocking rates may help prevent IBK. Early identification of the disease also helps prevent spread throughout the herd. Treatment is with early systemic use of a long-acting antibiotic such as tetracycline or florfenicol. Subconjunctival injections with procaine penicillin or other antibiotics are also effective, providing a "bubble" of antibiotic which releases into the eye slowly over several days.

Anti-inflammatory therapy can help shorten recovery times, but topical corticosteroids should be used with care if corneal ulcers are present.

"M. bovis" uses several different serotyped fimbriae as virulence factors, consequently pharmaceutical companies have exploited this to create vaccines. However, currently available vaccines are not reliable.

Myxomatosis (sometimes shortened to "myxo" or "myxy") is a disease that affects rabbits, caused by the "myxoma" virus. It was first observed in Uruguay in laboratory rabbits in the late 19th century. It was introduced into Australia in 1950 in an attempt to control the rabbit population (see Rabbits in Australia). Affected rabbits develop skin tumors, and in some cases blindness, followed by fatigue and fever; they usually die within 14 days of contracting the disease.

The disease is spread by direct contact with an affected animal or by being bitten by fleas or mosquitoes that have fed on an infected rabbit. The myxomatosis virus does not replicate in these insect hosts, but can be physically carried by an insect's mouthparts, i.e. from an infected rabbit to another susceptible animal. Due to the potential of insect vector transmission, pet rabbits may be susceptible in enzootic areas and vaccination is highly recommended.

An anthroponotic disease, or anthroponosis, is an infectious disease in which a disease causing agent carried by humans is transferred to other animals. It may cause the same disease or a different disease in other animals. Since humans do not generally inflict bite wounds on other animals, the method of transmissions is always a "soft" contact such as skin to skin transmission. An example is chytridiomycosis which can be spread by humans with the fungus on their skin handling frogs with bare hands.

The reverse situation, a disease transmitted from animals to humans, is known as zoonotic.

It can also be defined as a human-to-human infection with no animal vector.

Rabies is a viral zoonotic neuroinvasive disease which causes inflammation in the brain and is usually fatal. Rabies, caused by the rabies virus, primarily infects mammals. In the laboratory it has been found that birds can be infected, as well as cell cultures from birds, reptiles and insects. Animals with rabies suffer deterioration of the brain and tend to behave bizarrely and often aggressively, increasing the chances that they will bite another animal or a person and transmit the disease. Most cases of humans contracting the disease from infected animals are in developing nations. In 2010, an estimated 26,000 people died from rabies, down from 54,000 in 1990.

Rabies is also common in coyotes and can be a cause for concern if they interact with humans.

In the US, the Dietary Reference Intake for adults is 55 µg/day. In the UK it is 75 µg/day for adult males and 60 µg/day for adult females. 55 µg/day recommendation is based on full expression of plasma glutathione peroxidase. Selenoprotein P is a better indicator of selenium nutritional status, and full expression of it would require more than 66 µg/day.

Many human diseases can be transmitted to other primates, due to their extensive biological similarities. As a result, centers that hold, treat, or involve close proximity to primates and some other kinds of animals (for example zoos, researchers, and animal hospitals), often take steps to ensure animals are not exposed to human diseases they can catch. In some cases animals are routinely immunized with the same vaccines given to humans.

- Leishmaniasis - Both zoonotic and anthroponotic.

- Influenza, Measles, pneumonia and various other pathogens - Many primates.

- Tuberculosis - Both zoonotic and anthroponotic, with birds, cows, elephants, meerkats, mongooses, monkeys, and pigs known to have been affected.

Caseous lymphadenitis (CLA) is an infectious disease caused by the bacterium "Corynebacterium pseudotuberculosis" found mostly in goats and sheep that at present has no cure. It manifests itself predominantly in the form of large, pus-filled cysts on the neck, sides and udders of goats and sheep. The disease is spread mostly from an animal coming in contact with pus from a burst cyst on an infected animal, but the disease is highly contagious and is thought to also be spread by coughing or even by flies. Studies have found CL incidence in commercial goat herds as high as 30%.

In the past, notifiable diseases in the United States varied according to the laws of individual states. The Centers for Disease Control and Prevention and the Council of State and Territorial Epidemiologists (CSTE) also produced a list of nationally notifiable diseases that health officials should report to the CDC's National Notifiable Diseases Surveillance System (NNDSS). A uniform criterion for reporting diseases to the NNDSS was introduced in 1990.

In laboratory animals, prevention includes a low-stress environment, an adequate amount of nutritional feed, and appropriate sanitation measurements. Because animals likely ingest bacterial spores from contaminated bedding and feed, regular cleaning is a helpful method of prevention. No prevention methods are currently available for wild animal populations.

The OIE (World Organisation for Animal Health) monitors specific animal diseases on a global scale.

- Diseases Notifiable to the OIE