The most commonly available antiviral drugs for treating FIP are either feline recombinant interferon omega (Virbagen Omega, Virbac) or human interferon. Since the action of interferon is species-specific, feline interferon is more efficacious than human interferon.

An experimental antiviral drug called GC 376 was used in a field trial of 20 cats: 7 cats went into remission, 13 cats responded initially but relapsed and were euthanazed. This drug is not yet commercially available: watch the University of California Davis website for progress updates.

The go-to immunosuppressive drug in FIP is prednisolone.

An experimental polyprenyl immunostimulant (PI) is manufactured by Sass and Sass and tested by Dr. Al Legendre, who described survival over 1 year in three cats diagnosed with FIP and treated with the medicine. In a subsequent field study of 60 cats with non-effusive FIP treated with PI, 52 cats (87%) died before 200 days, but eight cats survived over 200 days from the start of PI treatment for and four of those survived beyond 300 days. There are anecdotal reports on the internet of cats surviving even longer.

Treatment depends on the type of opportunistic infection, but usually involves different antibiotics.

Individuals at higher risk are often prescribed prophylactic medication to prevent an infection from occurring. A patient's risk level for developing an opportunistic infection is approximated using the patient's CD4 T-cell count and sometimes other markers of susceptibility. Common prophylaxis treatments include the following:

Antibiotics are commonly used to prevent secondary bacterial infection. There are no specific antiviral drugs in common use at this time for FVR, although one study has shown that ganciclovir, PMEDAP, and cidofovir hold promise for treatment. More recent research has indicated that systemic famciclovir is effective at treating this infection in cats without the side effects reported with other anti-viral agents. More severe cases may require supportive care such as intravenous fluid therapy, oxygen therapy, or even a feeding tube. Conjunctivitis and corneal ulcers are treated with topical antibiotics for secondary bacterial infection.

Lysine is commonly used as a treatment, however in a 2015 systematic review, where the authors investigated all clinical trials with cats as well as "in vitro" studies, concluded that lysine supplementation is not effective for the treatment or prevention of feline herpesvirus 1 infection.

When infection attacks the body, "anti-infective" drugs can suppress the infection. Several broad types of anti-infective drugs exist, depending on the type of organism targeted; they include antibacterial (antibiotic; including antitubercular), antiviral, antifungal and antiparasitic (including antiprotozoal and antihelminthic) agents. Depending on the severity and the type of infection, the antibiotic may be given by mouth or by injection, or may be applied topically. Severe infections of the brain are usually treated with intravenous antibiotics. Sometimes, multiple antibiotics are used in case there is resistance to one antibiotic. Antibiotics only work for bacteria and do not affect viruses. Antibiotics work by slowing down the multiplication of bacteria or killing the bacteria. The most common classes of antibiotics used in medicine include penicillin, cephalosporins, aminoglycosides, macrolides, quinolones and tetracyclines.

Not all infections require treatment, and for many self-limiting infections the treatment may cause more side-effects than benefits. Antimicrobial stewardship is the concept that healthcare providers should treat an infection with an antimicrobial that specifically works well for the target pathogen for the shortest amount of time and to only treat when there is a known or highly suspected pathogen that will respond to the medication.

There is a vaccine for FHV-1 available (ATCvet code: , plus various combination vaccines), but although it limits or weakens the severity of the disease and may reduce viral shedding, it does not prevent infection with FVR. Studies have shown a duration of immunity of this vaccine to be at least three years. The use of serology to demonstrate circulating antibodies to FHV-1 has been shown to have a positive predictive value for indicating protection from this disease.

There is usually an indication for a specific identification of an infectious agent only when such identification can aid in the treatment or prevention of the disease, or to advance knowledge of the course of an illness prior to the development of effective therapeutic or preventative measures. For example, in the early 1980s, prior to the appearance of AZT for the treatment of AIDS, the course of the disease was closely followed by monitoring the composition of patient blood samples, even though the outcome would not offer the patient any further treatment options. In part, these studies on the appearance of HIV in specific communities permitted the advancement of hypotheses as to the route of transmission of the virus. By understanding how the disease was transmitted, resources could be targeted to the communities at greatest risk in campaigns aimed at reducing the number of new infections. The specific serological diagnostic identification, and later genotypic or molecular identification, of HIV also enabled the development of hypotheses as to the temporal and geographical origins of the virus, as well as a myriad of other hypothesis. The development of molecular diagnostic tools have enabled physicians and researchers to monitor the efficacy of treatment with anti-retroviral drugs. Molecular diagnostics are now commonly used to identify HIV in healthy people long before the onset of illness and have been used to demonstrate the existence of people who are genetically resistant to HIV infection. Thus, while there still is no cure for AIDS, there is great therapeutic and predictive benefit to identifying the virus and monitoring the virus levels within the blood of infected individuals, both for the patient and for the community at large.

Paracetamol (acetaminophen) and NSAIDs, such as ibuprofen, may be used to reduce fever and pain. Prednisone, a corticosteroid, while used to try to reduce throat pain or enlarged tonsils, remains controversial due to the lack of evidence that it is effective and the potential for side effects. Intravenous corticosteroids, usually hydrocortisone or dexamethasone, are not recommended for routine use but may be useful if there is a risk of airway obstruction, a very low platelet count, or hemolytic anemia.

There is little evidence to support the use of antivirals such as aciclovir and valacyclovir although they may reduce initial viral shedding. Although antivirals are not recommended for people with simple infectious mononucleosis, they may be useful (in conjunction with steroids) in the management of severe EBV manifestations, such as EBV meningitis, peripheral neuritis, hepatitis, or hematologic complications.

Although antibiotics exert no antiviral action they may be indicated to treat bacterial secondary infections of the throat, such as with streptococcus (strep throat). However, ampicillin and amoxicillin are not recommended during acute Epstein–Barr virus infection as a diffuse rash may develop.

Infectious mononucleosis is generally self-limiting, so only symptomatic or supportive treatments are used. The need for rest and return to usual activities after the acute phase of the infection may reasonably be based on the person's general energy levels. Nevertheless, in an effort to decrease the risk of splenic rupture experts advise avoidance of contact sports and other heavy physical activity, especially when involving increased abdominal pressure or the Valsalva maneuver (as in rowing or weight training), for at least the first 3–4 weeks of illness or until enlargement of the spleen has resolved, as determined by a treating physician.

No specific treatment is available, but antibiotics can be used to prevent secondary infections.

Vaccines are available (ATCvet codes: for the inactivated vaccine, for the live vaccine; plus various combinations).

Biosecurity protocols including adequate isolation, disinfection are important in controlling the spread of the disease.

WAD is typically self-limited, generally resolving without specific treatment. Oral rehydration therapy with rehydration salts is often beneficial to replace lost fluids and electrolytes. Clear, disinfected water or other liquids are routinely recommended.

Hikers who develop three or more loose stools in a 24-hour period – especially if associated with nausea, vomiting, abdominal cramps, fever, or blood in stools – should be treated by a doctor and may benefit from antibiotics, usually given for 3–5 days. Alternatively, a single dose azithromycin or levofloxacin may be prescribed. If diarrhea persists despite therapy, travelers should be evaluated and treated for possible parasitic infection.

"Cryptosporidium" can be quite dangerous to patients with compromised immune systems. Alinia (nitazoxanide) is approved by the FDA for treatment of "Cryptosporidium".

No specific cure is known. Treatment is largely supportive. Nonsteroidal anti-inflammatory drugs (NSAIDs) are indicated for tender lymph nodes and fever, and corticosteroids are useful in severe extranodal or generalized disease.

Symptomatic measures aimed at relieving the distressing local and systemic complaints have been described as the main line of management of KFD. Analgesics, antipyretics, NSAIDs, and corticosteroids have been used. If the clinical course is more severe, with multiple flares of bulky enlarged cervical lymph nodes and fever, then a low-dose corticosteroid treatment has been suggested.

The medications prescribed for acute toxoplasmosis are the following:

- Pyrimethamine — an antimalarial medication

- Sulfadiazine — an antibiotic used in combination with pyrimethamine to treat toxoplasmosis

- Combination therapy is usually given with folic acid supplements to reduce incidence of thrombocytopaenia.

- Combination therapy is most useful in the setting of HIV.

- Clindamycin

- Spiramycin — an antibiotic used most often for pregnant women to prevent the infection of their children.

(other antibiotics, such as minocycline, have seen some use as a salvage therapy).

If infected during pregnancy, spiramycin is recommended in the first and early second trimesters while pyrimethamine/sulfadiazine and leucovorin is recommended in the late second and third trimesters.

Since wilderness acquired diarrhea can be caused by insufficient hygiene, contaminated water, and (possibly) increased susceptibility from vitamin deficiency, prevention methods should address these causes.

In people with latent toxoplasmosis, the cysts are immune to these treatments, as the antibiotics do not reach the bradyzoites in sufficient concentration.

The medications prescribed for latent toxoplasmosis are:

- Atovaquone — an antibiotic that has been used to kill "Toxoplasma" cysts inside AIDS patients

- Clindamycin — an antibiotic that, in combination with atovaquone, seemed to optimally kill cysts in mice

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.

There is no specific treatment for infectious mononucleosis, other than treating the symptoms. In severe cases, steroids such as corticosteroids may be used to control the swelling of the throat and tonsils. Currently, there are no antiviral drugs or vaccines available.

It is important to note that symptoms related to infectious mononucleosis caused by EBV infection seldom last for more than 4 months. When such an illness lasts more than 6 months, it is frequently called chronic EBV infection. However, valid laboratory evidence for continued active EBV infection is seldom found in these patients. The illness should be investigated further to determine if it meets the criteria for chronic fatigue syndrome, or CFS. This process includes ruling out other causes of chronic illness or fatigue.

Subcutaneous cysts may be surgically opened to remove less mature bots. If more matured, cysts may be opened and "cuterebra" may be removed using mosquito forceps. Covering the pore in petroleum jelly may aide in removal. If larvae are discovered within body tissues, rather than subcutaneously, surgical removal is the only means of treatment. Ivermectin may be administered with corticosteroids to halt larval migration in cats presenting with respiratory cuterebriasis, but this is not approved for use in cats. There is not yet a known cure for cerebrospinal cuterebriasis.

A list of the more common and well-known diseases associated with infectious pathogens is provided and is not intended to be a complete listing.

Fortunately, severe systemic reaction to vaccine allergy is very rare in dogs. When it does occur, however, anaphylaxis is a life-threatening emergency. More often, dogs will develop urticaria, or hives within minutes of receiving a vaccine. When this occurs, a veterinarian will treat the reaction with antihistamines and corticosteroid drugs and this is usually effective. Future vaccine protocols must be modified according to the vaccine component suspected to have triggered the reaction.

The mainstay of treatment for tenosynovitis includes symptom alleviation, antibiotic therapy, and surgery. Mild tenosynovitis causing small scale swelling can be treated with non-steroidal anti-inflammatory drugs (NSAIDs) to reduce inflammation and as an analgesic. Resting the affected tendons is essential for recovery; a brace is often recommended. Physical or occupational therapy may also be beneficial in reducing symptoms.

Most infectious tenosynovitis cases should be managed with tendon sheath irrigation and drainage, with or without debridement of surrounding necrotic tissue, along with treatment with broad-spectrum antibiotics. In severe cases, amputation may even be necessary to prevent the further spread of infection. Following surgical intervention, antibiotic therapy is continued and adjusted based on the results of the fluid culture.

Treatment of VAS is through aggressive surgery. As soon as the tumor is recognized, it should be removed with very wide margins to ensure complete removal. Treatment may also include chemotherapy or radiation therapy. The most significant prognostic factor is initial surgical treatment. One study showed that cats with radical (extensive) initial surgery had a median time to recurrence of 325 days versus 79 days for cats with marginal initial excision. The expression of a mutated form of p53, a tumor suppressor gene, is found commonly in VAS and indicates a poorer prognosis.

Vaccines should be given in specific areas in order to: ease identification of which vaccine caused an adverse reaction, and ease removal of any vaccine-associated sarcoma.

In North America, vets adopted the practice of injecting specific limbs as far from the body as possible, with the rear "right for rabies", the rear "left for leukemia", and the right front shoulder (being careful to avoid the midline or interscapular space) for other vaccines (such as FVRCP).

This set of locations was not widely adopted outside of North America, and the international Vaccination Guidelines Group (VGG) made new recommendations that vaccines be administered:

- in subcutaneous (and not intramuscular) sites

- in the skin of the lateral thorax or abdomen (for easier excision of any FISS that occur)

- avoid the interscapular or intercostal regions (as more extensive surgical resection would be needed for sarcomas)

- in a different site on each occasion (either with general locations per species per year or diagrams of where administered on specific visit)

Other causes or associations of disease are: a compromised immune system, environmental toxins, radiation exposure, diet and lifestyle choices, stress, and genetics. Diseases may also be multifactorial, requiring multiple factors to induce disease. For example: in a murine model, Crohn's disease can be precipitated by a norovirus, but only when both a specific gene variant is present and a certain toxin has damaged the gut.