Fungi: Fungi are either one or more cellular decomposers and they are responsible for decomposition and recycling nutrients throughout the environment. They use elaborate compounds to be their sources of energy and carbon not photosynthesis which plants use. Fungi play an essential role in the balance of the ecosystem as fungi inhabit most habitats on earth as they prefer dark and moist conditions to be able to survive. They can grow in the most hostile environments in the world such as the tundra, however, most members of the fungi kingdom grows on the forest floor as the dark and damp environment has plenty of rich decaying debris from plants and animals to thrive on. In the forest environment, fungi plays a significant role as decomposers and recyclers where it is possible for members of different kingdoms to have the nutrients it needs to survive. If no organisms that decompose organic matter then the animal and plant food web would be incomplete as some elements such as nitrogen and phosphorus are required in huge capacities by the biological systems as they are not sufficient in the environment. When fungi eat decaying matter they release nitrogen and phosphorus from the decaying matter and this allows these elements to be accessible to other living organisms which require them to survive in the world. Fungi is used to maintain the continuous ecosystem for both plants and animals which share the same habitat because fungi helps to replenish the environment with nutrients as fungi are able to interact directly with other organisms in helpful but sometimes deadly ways. In plants, fungi are able to destroy plant tissues directly or through the production of vigorous toxins and this will end up in host death and it can even lead to poisoning in animals such as dogs and cats. A mycosis is a fungal disease that results from infection and direct damage from fungi. Fungi attacks animals directly by migrating and destroying tissues in the body. Some living organisms can display hypersensitivity to moulds and spores and this can cause strong and dangerous allergic reactions and this can have serious health effects on animals. When it comes to the reproduction of fungi, they can reproduce sexually and asexually. Asexual reproduction in fungi can occur by fragmentation, budding and by producing spores. In sexual reproduction, it occurs with homothallic or heterothallic mycelia and by producing spores too. In both sexual and asexual reproduction, fungi produce spores which then disperse into the environment by floating on the wind or by travelling on an animal. The spores that are formed from fungi are described as haploid cells and they undergo mitosis to form into multicellular haploid cells. Fungi are extremely affected by both physical and physicochemical factors such as temperature, aeration, pH, water potential and light. These factors don’t just affect the growth rate of the fungi but also act as triggers in the development pathways. Fungi like all living organisms depend on three fundamental factors to survive. These are air, food and water. Fungi is able to digest human food but also many materials that are used in buildings. Fungi are grouped into four categories when it comes to their temperature ranges for growth. Most fungi are strict aerobes and this means that they require oxygen in at least some stages of their lifecycle. Today we can group fungi into four different categories based on their oxygen relationships. Light affects the growth of fungi and it can be very dangerous as near-ultraviolet light and the noticeable parts of the spectrum from 380-720 nm can have little effect on the growth of fungi but it can stimulate pigmentation. The blue light that is used to see what the effects are on the growth of fungi can induce the production of carotenoid pigments in hyphae and the spores of some fungi. These carotenoid pigments also occur in algae and bacteria and is known to destroy all reactive oxygen species and the pigments will try and minimize any photo-induced damage. Melanins protect the cells from the reactive oxygen species and any radiation that is given off by ultraviolet light. Aspergillosis is a type of fungal infection that is caused by the Aspergillus, a species of common mould that is found throughout the environment. Examples of the common mould includes dust, straw and hay. Typically, an infection occurs when an organism that does not cause disease normally infects an animal, however, this is different in the case of Aspergillosis as it causes disease because the animal’s immune system and/ or body is weakened by a disease. The fungus can cause illness to humans and animals but most people are immune to the fungus therefore they do not develop any disease caused by Aspergillus. There are two types of this fungal infection and they are the nasal and disseminated form. Both types of the fungal infection can occur in cats and dogs but it is more common in dogs. Dolichocephalic and mesocephalic breeds are more susceptible to the nasal form of Aspergillosis and the disseminated form of the disease is more common in German Shepherds. The clinical signs of the nasal form of the fungal infection includes sneezing, nasal pain, bleeding from the nose, having a reduced appetite, a visible swollen nose and long-term nasal discharge coming from the nose. In some cases of the nasal infection, there can be a loss of pigment or tissue on the surface of the nose. The clinical signs of the disseminated infection can develop abruptly or gradually over a period of time and it can include spinal pain or lameness due to infection and cause inflammation of the animal’s bone marrow and bones. There are some other signs of the infection occurring in cats and dogs but they are not specific to the infection and these include fever, vomiting and anorexia due to weight loss. Blastomycosis is an essential yeast-like fungal infection that is caused by Blastomyces dermatitidis which is found in decaying wood and soil. This fungal infection is most frequent in male dogs but female dogs are susceptible to the infection. Dogs who are constantly exposed to environments where Blastomyces dermatitidisexists are at increased risk. Large dog breeds that weigh at least 22kg and sporting breeds are also at risk of the fungal infection. The fungus thrives in wet environments such as riverbanks, lakes and swamps as damp soil that lacks direct sunlight fosters growth of the fungus. It is present in areas that have rich decaying matter such as wooded areas, forest floors and farms. The clinical signs of this fungal infection include fever, loss of appetite which then causes weight loss, discharge from the eye and inflammation of the eye specially the iris, breathing difficulty and skin lesions that are filled with pus. Blastomycosis occurs when the dog inhales the airborne fungal spores of the fungi after contaminated soil has been disturbed. This can occur from an activity such as digging in the dirt or following a scent trail. The fungus spores can enter through the skin. Exposure to areas that have decaying matter, been recently excavated or with water can increase the risk of exposure to the fungus and consequent development of the disease.