Diagnosis is achieved most commonly by serologic testing of the blood for the presence of antibodies against the ehrlichia organism. Many veterinarians routinely test for the disease, especially in enzootic areas. During the acute phase of infection, the test can be falsely negative because the body will not have had time to make antibodies to the infection. As such, the test should be repeated. A PCR (polymerase chain reaction) test can be performed during this stage to detect genetic material of the bacteria. The PCR test is more likely to yield a negative result during the subclinical and chronic disease phases. In addition, blood tests may show abnormalities in the numbers of red blood cells, white blood cells, and most commonly platelets, if the disease is present. Uncommonly, a diagnosis can be made by looking under a microscope at a blood smear for the presence of the "ehrlichia" morulae, which sometimes can be seen as intracytoplasmic inclusion bodies within a white blood cell.

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.

In endemic areas, a high index of suspicion is warranted, especially with a known exposure to ticks. The diagnosis can be confirmed by using PCR. A peripheral blood smear can also be examined for intracytoplasmic inclusions called morulae.

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.

Clinically, HGA is essentially indistinguishable from human monocytic ehrlichiosis, the infection caused by "Ehrlichia chaffeensis", and other tick-borne illnesses such as Lyme disease may be suspected. As Ehrlichia serologies can be negative in the acute period, PCR is very useful for diagnosis.

No human vaccine is available for ehrlichiosis. Tick control is the main preventive measure against the disease. However, in late 2012 a breakthrough in the prevention of CME (canine monocytic ehrlichiosis) was announced when a vaccine was accidentally discovered by Prof. Shimon Harrus, Dean of the Hebrew University of Jerusalem's Koret School of Veterinary Medicine.

Tick exposure is often overlooked. For patients living in high-prevalence areas who spend time outdoors, a high degree of clinical suspicion should be employed.

Ehrlichia serologies can be negative in the acute period. PCR is therefore the laboratory diagnostic tool of choice.

Diagnosis of PHF is accomplished by measuring antibody titers or PCR testing to look for the bacterium in the blood and feces. However, most veterinarians opt to initiate treatment right away, as the disease can progress quite quickly. Veterinarians may also run complete blood counts and chemistry and electrolyte panels to determine the course of care. Radiographs may be taken to track the progress of laminitic horses.

Currently, there is no vaccine against human granulocytic anaplasmosis, so antibiotics are the only form of treatment. The best way to prevent HGA is to prevent getting tick bites.

If ehrlichiosis is suspected, treatment should not be delayed while waiting for a definitive laboratory confirmation, as prompt doxycycline therapy has been associated with improved outcomes. Doxycycline is the treatment of choice.

Presentation during early pregnancy can complicate treatment.Rifampin has been used in pregnancy and in patients allergic to doxycycline.

While a vaccine is available for PHF, it does not cover all strains of the bacterium, and recent vaccine failures seem to be on the rise. Additionally, the vaccine usually produces a very weak immune response, which may only lessen the severity of the disease rather than prevent it. The vaccine is administered twice a year, in early spring and in early summer, with the first one inoculation given before the mayflies emerge and the second administered as a booster.

Some veterinarians have started making recommendations for farm management to try to prevent this disease:

- Maintaining riparian barriers along bodies of water may encourage aquatic insects to stay near their places of origin

- Turning off outside lights around the barn will prevent insects from being attracted

- Cleaning water buckets and feed areas frequently and keeping food covered will reduce the chance that the horse will accidentally ingest infected insects

Serological testing is typically used to obtain a definitive diagnosis. Most serological tests would succeed only after a certain period of time past the symptom onset (usually a week). The differential diagnosis list includes typhus, ehrlichiosis, leptospirosis, Lyme disease and virus-caused exanthema (measles or rubella).

In the United States, certain breed clubs are strongly recommending screening for "Leishmania", especially in imported breeding stock from endemic locations. For reasons yet unidentified The Foxhound and Neapolitan Mastiff seem to be predisposed or at higher risk for disease. The Italian Spinone Club of America is also requesting all breeders and owners to submit samples for testing; the club reported 150 Spinone Italiano dogs have tested positive in the United States.

In the United States, the following veterinary colleges and government bodies assist with testing and treatment of "Leishmania"-positive dogs:

- Centers for Disease Control and Prevention on Leishmaniasis in dogs

- Iowa State University Department of Pathology

- North Carolina State University College of Veterinary Medicine

Diagnostic testing includes molecular biology and genetic techniques which provide high accuracy and high sensitivity/specificity. The most commonly employed methods in medical laboratories include Enzyme-Linked Immunosorbent Assays, aka ELISA (among other serological assays) and DNA amplification via Polymerase Chain Reaction (PCR).

The Polymerase Chain Reaction(PCR) method for detecting "Leishmania" DNA is a highly sensitive and specific test, producing accurate results in a relatively short amount of time.

A study completed in which Foxhounds were tested using PCR showed that approximately 20% of the tested dogs were positive for leishmaniasis; the same population tested with serological/antibody assays showed only 5% positive.

Diagnosis can be complicated by false positives caused by the leptospirosis vaccine and false negatives caused by testing methods lacking sufficient sensitivity.

Humans contract the disease after a bite by an infected tick of the species "Amblyomma americanum".

Those with an underlying immunodeficiency (such as HIV) appear to be at greater risk of contracting the disease. Compared to HME, ewingii ehrlichiosis has a decreased incidence of complications.

Like "Anaplasma phagocytophilum", the causative agent of human granulocytic ehrlichiosis, Ehrlichia ewingii infects neutrophils. Infection with "E. ewingii" may delay neutrophil apoptosis.

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.

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.

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.

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.

In areas where the known vector is a sandfly, deltamethrin collars worn by the dogs has been proven to be 86% effective. The sandfly is most active at dusk and dawn; keeping dogs indoors during those peak times will help minimize exposure.

Unfortunately, there is no one answer for leishmaniasis prevention, nor will one vaccine cover multiple species. "Different virulence factors have been identified for distinct "Leishmania" species, and there are profound differences in the immune mechanisms that mediate susceptibility/resistance to infection and in the pathology associated with disease."

In 2003, Fort Dodge Wyeth released the Leshmune vaccine in Brazil for "L. donovani" (also referred to as "kala-azar" in Brazil). Studies indicated up to 87% protection. Most common side effects from the vaccine have been noted as anorexia and local swelling.

The president of the Brazil Regional Council of Veterinary Medicine, Marcia Villa, warned since vaccinated dogs develop antibodies, they can be difficult to distinguish from asymptomatic, infected dogs.

Studies also indicate the Leshmune vaccine may be reliable in treating "L. chagasi", and a possible treatment for dogs already infected with "L. donovani".

Methicillin-resistant Staphylococcus aureus (MRSA) evolved from Methicillin-susceptible Staphylococcus aureus (MSSA) otherwise known as common "S. aureus". Many people are natural carriers of "S. aureus", without being affected in any way. MSSA was treatable with the antibiotic methicillin until it acquired the gene for antibiotic resistance. Though genetic mapping of various strains of MRSA, scientists have found that MSSA acquired the mecA gene in the 1960s, which accounts for its pathogenicity, before this it had a predominantly commensal relationship with humans. It is theorized that when this "S. aureus" strain that had acquired the mecA gene was introduced into hospitals, it came into contact with other hospital bacteria that had already been exposed to high levels of antibiotics. When exposed to such high levels of antibiotics, the hospital bacteria suddenly found themselves in an environment that had a high level of selection for antibiotic resistance, and thus resistance to multiple antibiotics formed within these hospital populations. When "S. aureus" came into contact with these populations, the multiple genes that code for antibiotic resistance to different drugs were then acquired by MRSA, making it nearly impossible to control. It is thought that MSSA acquired the resistance gene through the horizontal gene transfer, a method in which genetic information can be passed within a generation, and spread rapidly through its own population as was illustrated in multiple studies. Horizontal gene transfer speeds the process of genetic transfer since there is no need to wait an entire generation time for gene to be passed on. Since most antibiotics do not work on MRSA, physicians have to turn to alternative methods based in Darwinian medicine. However prevention is the most preferred method of avoiding antibiotic resistance. By reducing unnecessary antibiotic use in human and animal populations, antibiotics resistance can be slowed.

Tetracycline-group antibiotics (doxycycline, tetracycline) are commonly used. Chloramphenicol is an alternative medication recommended under circumstances that render use of tetracycline derivates undesirable, such as severe liver malfunction, kidney deficiency, in children under nine years and in pregnant women. The drug is administered for seven to ten days.

The treatment for bacillary angiomatosis is erythromycin given for three to four months.

An emerging infectious disease (EID) is an infectious disease whose incidence has increased in the past 20 years and could increase in the near future. Emerging infections account for at least 12% of all human pathogens. EIDs are caused by newly identified species or strains (e.g. Severe acute respiratory syndrome, HIV/AIDS) that may have evolved from a known infection (e.g. influenza) or spread to a new population (e.g. West Nile fever) or to an area undergoing ecologic transformation (e.g. Lyme disease), or be "reemerging" infections, like drug resistant tuberculosis. Nosocomial (hospital-acquired) infections, such as methicillin-resistant Staphylococcus aureus are emerging in hospitals, and extremely problematic in that they are resistant to many antibiotics. Of growing concern are adverse synergistic interactions between emerging diseases and other infectious and non-infectious conditions leading to the development of novel syndemics. Many emerging diseases are zoonotic - an animal reservoir incubates the organism, with only occasional transmission into human populations.

A canine vector-borne disease (CVBD) is one of "a group of globally distributed and rapidly spreading illnesses that are caused by a range of pathogens transmitted by arthropods including ticks, fleas, mosquitoes and phlebotomine sandflies." CVBDs are important in the fields of veterinary medicine, animal welfare, and public health. Some CVBDs are of zoonotic concern.

Many CVBD infect humans as well as companion animals. Some CVBD are fatal; most can only be controlled, not cured. Therefore, infection should be avoided by preventing arthropod vectors from feeding on the blood of their preferred hosts. While it is well known that arthropods transmit bacteria and protozoa during blood feeds, viruses are also becoming recognized as another group of transmitted pathogens of both animals and humans.

Some "canine vector-borne pathogens of major zoonotic concern" are distributed worldwide, while others are localized by continent. Listed by vector, some such pathogens and their associated diseases are the following:

- Phlebotomine sandflies (Psychodidae): "Leishmania amazonensis", "L. colombiensis", and "L. infantum" cause visceral leishmaniasis (see also canine leishmaniasis). "L. braziliensis" causes mucocutaneous leishmaniasis. "L. tropica" causes cutaneous leishmaniasis. "L. peruviana" and "L. major" cause localized cutaneous leishmaniasis.

- Triatomine bugs (Reduviidae): "Trypanosoma cruzi" causes trypanosomiasis (Chagas disease).

- Ticks (Ixodidae): "Babesia canis" subspecies ("Babesia canis canis", "B. canis vogeli", "B. canis rossi", and "B. canis gibsoni" cause babesiosis. "Ehrlichia canis" and "E. chaffeensis" cause monocytic ehrlichiosis. "Anaplasma phagocytophilum" causes granulocytic anaplasmosis. "Borrelia burgdorferi" causes Lyme disease. "Rickettsia rickettsii" causes Rocky Mountain spotted fever. "Rickettsia conorii" causes Mediterranean spotted fever.

- Mosquitoes (Culicidae): "Dirofilaria immitis" and "D. repens" cause dirofilariasis.

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.

The most common medications used to treat coccidian infections are in the sulfonamide antibiotic family.

Depending on the pathogen and the condition of the animal, untreated coccidiosis may clear of its own accord, or become severe and damaging, and sometimes cause death.