These collars are the most restrictive type, and are mostly used for extreme situations such as grievous body injuries or neck injuries. The collars are fastened by the veterinarian, and owners of animals should adjust the collars only under the instruction of the vet. Avian spherical collar Made of medical grade polycarbonate plastic (Lexan), these collars are spherical and cover parts of the body of birds instead of acting as a barrier like the other types of collars. These collars range in size to accommodate a wide variety of bird species. Birds wearing these collars are often grounded and unable to fly until the time that they are cured. Medical reasons for Elizabethan collars Injury or surgery In order to prevent the animal from irritating a wound or removing stitches while self grooming, Elizabethan collars are used to either prevent the animal from licking/biting its wound or using its limbs to scratch their head, eyes, or ears. The collar can also be used to restrain animals with self-destructive habits, either from poor training or mental illness. Allergies or flea treatment In addition to medicine such as ointments and pills, Elizabethan collars are necessary when dealing with an animal that is suffering from an allergy reaction. The main reasons are to prevent the animal from ingesting any of the medicine being applied on the skin, or to prevent it from harming itself in the infected area. Viruses and fungus In addition to preventing the animal from harming themselves or ingesting medicine being applied on their skins, Elizabethan collars also prevent the animal from further spreading the infection due to it licking, biting, or scratching itself elsewhere after touching the infection area. Hot spots, an infection that could be attributed to multiple reasons, are the most common infections that could be spread due to an animal licking or scratching the area. Dangers of Elizabethan collars The use of the Elizabethan collar has been shown in one study to increase the number of fleas found on the bodies of flea-infested cats compared to flea-infested cats that did not wear the collar. This is attributed to the collar's preventing the animal from being able to properly groom. Some animals can be allergic to the plastic often used in the collars. Alternatives include inflatable and soft fabric collars. See also Dog booties Dog collar Cat collar Muzzle (device) Neck brace Rug (animal covering), or dog/cat