Although the exact cause of feline acne is unknown, some causes include:

- Hyperactive sebaceous glands

- Poor hygiene

- Stress

- Developing secondary to fungal, viral, and bacterial infections

- Reaction to medication

- Drinking from plastic containers to which the cat is allergic

- Demodicosis or mange, causing itchiness and hair loss

- Suppressed immune system

- Hair follicles that don't function properly

- Rubbing the chin (to display affection or mark territory) on non-sanitized household items

- Hormonal imbalance

- Contracting the infection from other cats in the same household

The hypothesis that pesticide use has contributed to declining amphibian populations has been suggested several times in the literature. Interactions between pesticides and chytridiomycosis were examined in 2007, and sublethal exposure to the pesticide carbaryl (a cholinesterase inhibitor) was shown to increase susceptibility of foothill yellow-legged frogs ("Rana boylii") to chytridiomycosis. In particular, the skin peptide defenses were significantly reduced after exposure to carbaryl, suggesting pesticides may inhibit this innate immune defence, and increase susceptibility to disease.

The transmission of Tinea Barbae to humans occurs through contact of an infected animal to the skin of a human. Infection can occasionally be transmitted through contact of infected animal hair on human skin. Tinea Barbae is very rarely transmitted through human to human contact but is not completely impossible.

The diagnosis of flea allergy dermatitis is complicated by the grooming habits of pets. Cats in particular are very efficient at grooming out fleas, often removing any evidence of infestation. Fleas begin biting within 5 minutes of finding a host, and there are no flea treatments that kill fleas before biting occurs.

About 14 million people, mainly children, are treated annually for head lice in the United States alone. Only a small proportion of those treated, however, may have objective evidence of an extant infestation. High levels of louse infestations have also been reported from all over the world including Denmark, Sweden, U.K., France and Australia.

Normally head lice infest a new host only by close contact between individuals, making social contacts among children and parent child interactions more likely routes of infestation than shared combs, brushes, towels, clothing, beds or closets. Head-to-head contact is by far the most common route of lice transmission.

The United Kingdom's National Health Service, and many American health agencies, report that lice "prefer" clean hair, because it's easier to attach eggs and to cling to the strands.

Head lice ("Pediculus humanus capitis") are not known to be vectors of diseases, unlike body lice ("Pediculus humanus humanus"), which are known vectors of epidemic or louse-borne typhus ("Rickettsia prowazekii"), trench fever ("Rochalimaea quintana") and louse-borne relapsing fever ("Borrelia recurrentis").

The amphibian chytrid fungus appears to grow best between 17 and 25 °C, and exposure of infected frogs to high temperatures can cure the frogs. In nature, the more time individual frogs were found at temperatures above 25 °C, the less likely they were to be infected by the amphibian chytrid. This may explain why chytridiomycosis-induced amphibian declines have occurred primarily at higher elevations and during cooler months. Naturally produced cutaneous peptides can inhibit the growth of "B. dendrobatidis" when the infected amphibians are around temperatures near 10 °C (50 °F), allowing species like the northern leopard frog ("Rana pipiens") to clear the infection in about 15% of cases.

Although many declines have been credited to the fungus "B. dendrobatidis", some species resist the infection and some populations can survive with a low level of persistence of the disease. In addition, some species that seem to resist the infection may actually harbor a nonpathogenic form of "B. dendrobatidis".

Some researchers contend the focus on chytridiomycosis has made amphibian conservation efforts dangerously myopic. A review of the data in the IUCN Red List found the threat of the disease was assumed in most cases, but no evidence shows, in fact, it is a threat. Conservation efforts in New Zealand continue to be focused on curing the critically endangered native Archey's frog, "Leiopelma archeyi", of chytridiomycosis, though research has shown clearly that they are immune from infection by "B. dendrobatidis" and are dying in the wild of other still-to-be identified diseases. In Guatemala, several thousand tadpoles perished from an unidentified pathogen distinct from "B. dendrobatidis".

Tinea barbæ (also known as "Barber's itch," "Ringworm of the beard," and "Tinea sycosis") is a fungal infection of the hair. Tinea barbae is due to a dermatophytic infection around the bearded area of men. Generally, the infection occurs as a follicular inflammation, or as a cutaneous granulomatous lesion, i.e. a chronic inflammatory reaction. It is one of the causes of Folliculitis. It is most common among agricultural workers, as the transmission is more common from animal-to-human than human-to-human. The most common causes are "Trichophyton mentagrophytes" and "T. verrucosum".

The aim of treatment is to relieve the allergy-induced itch and to remove the fleas from the pet and its home environment. In some cases, secondary bacterial or yeast infections will also need treatment before the itching subsides. Environmental flea control includes using flea foggers or bombs, vacuuming, and treating pet bedding by washing on a hot cycle (over 60 degrees Celsius) in the washing machine. The current on-pet treatment recommended by veterinary dermatologists is spinosad (Comfortis) monthly and nitenpyram (Capstar or generics) every 48 hours until improvement.

Many pets with FAD may also have other allergies, such as allergies to food, contact allergies, and atopic dermatitis.

Atopy is a hereditary and chronic (lifelong) allergic skin disease. Signs usually begin between 6 months and 3 years of age, with some breeds of dog, such as the Golden Retriever showing signs at an earlier age. Dogs with atopic dermatitis are itchy, especially around the eyes, muzzle, ears and feet. In severe cases the irritation is generalised. If the allergens are seasonal, the signs of irritation are similarly seasonal. Many dogs with house dust mite allergy have perennial disease. Some of the allergens associated with atopy in dogs include pollens of trees, grasses and weeds, as well as molds and House dust mite. Ear and skin infections with the bacteria "Staphylococcus pseudintermedius" and the yeast "Malassezia pachydermatis" are common secondary to atopic dermatitis.

Food allergy can be associated with identical signs and some authorities consider food allergy to be a type of atopic dermatitis.

Diagnosis of atopic dermatitis is by elimination of other causes of irritation including fleas, scabies and other parasites such as Cheyletiella and lice. Food allergy can be identified through the use of elimination diet trials in which a novel or hydrolysed protein diet is used for a minimum of 6 weeks and allergies to aeroallergens can be identified using intradermal allergy testing and/or blood testing (allergen-specific IgE ELISA).

Treatment includes avoidance of the offending allergens if possible, but for most dogs this is not practical or effective. Other treatments modulate the adverse immune response to allergens and include antihistamines, steroids, ciclosporin and immunotherapy (a process in which allergens are injected to try to induce tolerance). In many cases shampoos, medicated wipes and ear cleaners are needed to try to prevent the return of infections.

New research into T-cell receptor peptides and their effects on dogs with severe, advanced atopic dermatitis are being investigated.

Most of the mites which cause this affliction to humans are from the order Acari, hence the name Acariasis. The entire taxonomic classification to order would be:

- Kingdom: Animalia

- Phylum: Arthropoda

- Subphylum: Chelicerata

- Class: Arachnida

- Order: Acari (At the order level, there is still substantial argument among researchers as to how to categorize Acari. Some call it a subclass, others a superorder, "Acarina".)

Specific species involved include:

- Acariformes

- Trombidiformes

- "Trombicula" species (trombiculosis or chiggers)

- "Demodex" species (Demodicosis)

- "Pyemotes tritici"

- "Cheyletiella"

- Sarcoptiformes

- "Sarcoptes scabiei" (Scabies)

- Parasitiformes

- "Dermanyssus gallinae"

- "Liponyssoides sanguineus"

- "Ornithonyssus bacoti", "Ornithonyssus bursa", "Ornithonyssus sylviarum"

- Another candidate is "Androlaelaps casalis". However, based on this mite's life style as a predator on other mite species (such as the previously-mentioned "Dermanyssus gallinae"), it is highly unlikely to be a cause of acariasis.

Some of these reflect reports existing of human infestation by mites previously believed not to prey on humans.

Placing the cat's water in a shallow dish may prevent the chin from absorbing the bacteria in the water while the cat is drinking. If the cat is allergic to plastics or dyes, using a stainless-steel or glass dish is recommended . Cats may also have food allergies that make the development of acne more likely, so that switching kibble, or changing to a hydrolysed diet may be effective. Maintaining good hygiene and grooming habits make the development of feline acne less likely. Washing and exfoliating the chin with a gentle benzoyl-peroxide solution also may be preventive of further outbreaks.

This condition, is caused by body louse ("Pediculus humanus humanus", sometimes called "Pediculus humanus corporis") is a louse which infests humans and is adapted to lay eggs in clothing, rather than at the base of hairs, and is thus of recent evolutionary origin. Pediculosis is a more serious threat due to possible contagion of diseases such as typhus. Epidemiology and treatment of human body lice is described in the article on body lice.

Pemphigus foliaceus is the most common autoimmune disease of the dog. Blisters in the epidermis rapidly break to form crusts and erosions most often affecting the face and ears initially, but in some cases spreading to include the whole body. The pawpads can be affected causing marked hyperkeratosis (thickening of the pads with scale). Other autoimmune diseases include bullous pemphigoid and epidermolysis bullosa acquisita.

Treatment of autoimmune skin conditions requires treatment to markedly reduce the abnormal immune response; steroids, azathoprine and other drugs are used as immunosuppressive agents.

Medical doctors and dermatologists can still misdiagnose this rash as many are unfamiliar with parasitism, not trained in it, or if they do consider it, cannot see the mites.

Different methods for detection are recognized for different acariasis infections. Human acariasis with mites can occur in the gastrointestinal tract, lungs, urinary tracts and other organs which not have been well-studied. For intestinal acariasis with symptoms such as abdominal pain, diarrhea, and phohemefecia (is this hemafecia?), human acariasis is diagnosed by detection of mites in stools. For pulmonary acariasis, the presence of mites in sputum is determined by identifying the presence and number of mites in the sputum of patients with respiratory symptoms. Both physical and chemical methods for liquefaction of sputum have been developed.

Pulicosis (also known as "flea bites") is a skin condition caused by several species of fleas, including the cat flea ("Ctenocephalides felis") and dog flea ("Ctenocephalides canis"). This condition can range from mild irritation to severe irritation. In some cases, 48 to 72 hours after being bitten, a more severe rash-like irritation may begin to spread across the body. Symptoms include swelling of the bitten area, erythema, ulcers of the mouth and throat, restlessness, and soreness of the areolae. In extreme cases, within 1 week after being bitten, the condition may spread through the lymph nodes and begin affecting the central nervous system. Permanent nerve damage can occur.

If they receive an excessive number of bites, pets can also develop flea allergy dermatitis, which can potentially be fatal if no actions are taken. However, dogs and cats are not the only ones that are at risk. Humans can suffer from flea bites and, depending on a variety of factors, the bites can cause much pain and discomfort.

The most important infectious skin diseases of cats is ringworm or dermatophytosis. Other cat skin infections include parasitic diseases like mange and lice infestation.

Other ectoparasites, including flea and tick infestations are not considered directly contagious but are acquired from an environment where other infested hosts have established the parasite's life cycle.

Another common skin infection is cat bite abscess. A mixture of bacteria introduced by a bite wound cause infections in pockets under the skin and affected cats often show manic depression and fever.

It is caused by either "Bartonella henselae" or "B. quintana".

- "B. henselae" is most often transmitted through a cat scratch or bite, though ticks and fleas may also act as vectors.

- "B. quintana" is usually transmitted by lice.

It can manifest in people with AIDS and rarely appears in those who are immunocompetent.

The cat must have a supply of niacin, as cats cannot convert tryptophan into niacin like dogs. However, diets high in corn and low in protein can result in skin lesions and scaly, dry, greasy skin, with hair loss. Another B vitamin, biotin, if deficient causes hair loss around the eyes and face. A lack of B vitamins can be corrected by supplementing with a vitamin B complex, and brewers yeast.

While curable, BA is potentially fatal if not treated. BA responds dramatically to several antibiotics. Usually, erythromycin will cause the skin lesions to gradually fade away in the next four weeks, resulting in complete recovery. Doxycycline may also be used. However, if the infection does not respond to either of these, the medication is usually changed to tetracycline. If the infection is serious, then a bactericidal medication may be coupled with the antibiotics

If a cat is carrying "Bartonella henselae", then it may not exhibit any symptoms. Cats may be bacteremic for weeks to years, but infection is more common in young cats. Transmission to humans is thought to occur via flea feces inoculated into a cat scratch or bite, and transmission between cats occurs only in the presence of fleas. Therefore, elimination and control of fleas in the cat's environment are key to prevention of infection in both cats and humans.

Many species of arthropods (insects, arachnids and others) regularly or occasionally bite or sting human beings. Insect saliva contains anticoagulants and enzymes that cause local irritation and allergic reactions. Insect venoms can be delivered by their stingers, which often are modified ovipositors, or by their mouthparts. Insect, spider and scorpion venom can cause serious injury or death. Dipterans account for the majority of insect bites, while hymenopterans account for the majority of stings. Among arachnids spider bites are the most common. Arthropods bite or sting humans for a number of reasons including feeding or defense. Arthropods are major vectors of human disease, with the pathogens typically transmitted by bites.

The cat should be taken to a veterinarian. The most suspected cause of skin problems in cats will be fleas. Other causes of over-grooming are not as easily ascertained. As household antiseptics are known to be toxic to cats, veterinary antiseptics for cats can be used to treat open sores, if they do occur. Sores can also be treated with cream, oral or injected anti-inflammatories, however if the problem continues to recur it may be more cost effective to subject the cat to laboratory testing early on. It may be difficult to keep a clean dressing on a cat's belly, and an anti-lick collar is adequate to let the wound heal. If an anti lick collar is used, a soft anti-lick collar is less cumbersome, although they are less durable. If the cat wears a plastic anti-lick collar, it may use the edge of the collar to grind against existing wounds, making them worse. A soft anti lick collar will become less effective as it is kicked out of the shape by the cat's hind leg, and will need prompt replacement. The cat can sanitize the wound if the collar is removed for daily short periods of time, also giving the cat an opportunity for an overall grooming. Scratches and wounds can heal completely using this method. When the cat stops wearing the collar, thinned hair, redness of skin or cracked nipples on the cat are early indicators that the cat has started to over-groom again.

Antidepressants for cats may be suggested by a vet.

Due to the high number of hosts, eradication of tungiasis is not feasible, at least not easily so. Public health and prevention strategies should then be done with elimination as the target. Better household hygiene, including having a cemented rather than a sand floor, and washing it often, would lower the rates of tungiasis significantly.

Though vaccines would be useful, due to the ectoparasitic nature of chigoe flea, they are neither a feasible nor an effective tool against tungiasis. Nevertheless, due to the high incidence of secondary infection, those at risk of tungiasis should get vaccinated against tetanus. A better approach is to use repellents that specifically target the chigoe flea. One very successful repellent is called Zanzarin, a derivative of coconut oil, jojoba oil, and aloe vera. In a recent study involving two cohorts, the infestation rates dropped 92% on average for the first one and 90% for the other. Likewise, the intensity of the cohorts dropped by 86% and 87% respectively. The non-toxic nature of Zanzarin, combined with its "remarkable regression of the clinical pathology" make this a tenable public health tool against tungiasis.

The use of pesticide, like DDT, has also led to elimination of the "Tunga penetrans", but this control/prevention strategy should be utilized very carefully, if at all, because of the possible side effects such pesticides can have on the greater biosphere. In the 1950s, there was a worldwide effort to eradicate malaria. As part of that effort, Mexico launched the Campaña Nacional para la Erradicación de Paludismo, or the National Campaign for the Eradication of Malaria. By spraying DDT in homes, the Anopheles a genus of mosquitoes known to carry the deadly Plasmodium falciparum was mostly eliminated. As a consequence of this national campaign, other arthropods were either eliminated or significantly reduced in number, including the reduviid bug responsible for Chagas disease (American Trypanosomiasis) and "T. penetrans". Controlled, in-home spraying of DDT is effective as it gives the home immunity against arthropods while not contaminating the local water supplies and doing as much ecological damage as was once the case when DDT was first introduced.

While other species gradually gained resistance to DDT and other insecticides that were used, "T. penetrans did" not; as a result, the incidence of tungiasis in Mexico is very low when compared to the rest of Latin America, especially Brazil, where rates in poor areas have been known to be as high or higher than 50%. There was a 40-year period with no tungiasis cases in Mexico. It was not until August 1989 that three Mexican patients presented with the disease. Though there were other cases of tungiasis reported thereafter, all were acquired in Africa.

Because of the relatively rapid onset of tungiasis, the incubation period tends to be short. Although some reddening around the site of penetration occurs, the first symptoms are perceived in stage 2 as itching and severe pain, usually a day after penetration.

Areas affected are those the cat can access most easily, including the abdomen, legs, flank, and chest.

- Baldness, usually beginning with the abdomen

- Obvious over-grooming (although some cats may only engage in the behavior in the absence of owners)

- Redness, rashes, pus, scabs on the bald area or areas traumatized by over-grooming

- A highly irritable cat may even cut its face with the claw of its hind foot if over-zealously scratching the back of its head.

Cat-scratch disease has a worldwide distribution, however it is a nonreportable disease in humans and therefore public health data on this disease is inadequate. Geographical location, present season and variables associated with cats (such as exposure and degree of flea infestation) all play a factor in the prevalence of Cat-scratch disease within a population. In warmer climates, the incidence of Cat-scratch disease is more prevalent during the fall and winter months. The higher rate of Cat-scratch disease during those months may be attributed to the breeding season for adult cats, which allows for the birth of kittens". B henselae," the bacterium responsible for causing Cat-scratch disease, is more prevalent in younger cats [less than one year old] than it is in adult cats.

To determine recent incidence of Cat-scratch disease in the United States, the Truven Health MarketScan Commercial Claims and Encounters database was analyzed in a case control study from 2005-2013. The database consisted of healthcare insurance claims for employees, their spouses, and their dependents. All participants were under 65 years of age, from all 50 states. The length of the study period was 9 years and was based off 280,522,578 person-years; factors such as year, length of insurance coverage, region, age, and sex were used to calculate the person-years incidence rate to eliminate confounding variables among the entire study population. 13,273 subjects were diagnosed with Cat-scratch disease, both in and outpatient cases were analyzed. The study revealed an incidence rate of 4.5/100,000 outpatient cases of Cat-scratch disease. For inpatient cases, the incidence rate was much lower at 0.19/100,000 population. Incidence of Cat-scratch disease was highest in 2005 among outpatient cases and then slowly declined. The Southern states saw the most significant decrease of incidence overtime. Mountain regions have the lowest incidence of this disease because fleas are not a common vector found in these areas.

Distribution of Cat-scratch disease among children aged 5-9 were of the highest incidence in the analyzed database, followed by woman aged 60-64. Incidence among female patients was higher than that among male patients in all age groups. According to data on social trends, women are more likely to own a cat over men; which supports higher incidence rates of this disease in women. Risk of contracting Cat-scratch disease increases as the number of cats residing in the home increases. The number of pet cats in the United States is estimated to be at 57 million. Due to the large population of cats residing in the United States, the ability of this disease to continue to infect humans is vast. Laboratory diagnosis of Cat-scratch disease has improved in recent years, which may support an increase in incidence of Cat-scratch disease in future populations.