18, February 2011) states that sexual contact with animals is almost never a clinically significant problem by itself; it also states that there are several kinds of zoophiles:

Additionally, zoophiles in categories 2, 3, and 8 (romantic zoophiles, zoophilic fantasizers, and regular zoophiles) are the most common, while zoophiles found in categories 6 and 7 (sadistic bestials and opportunistic zoophiles) are the least common.Zoophilia may reflect childhood experimentation, sexual abuse or lack of other avenues of sexual expression. Exclusive desire for animals rather than humans is considered a rare paraphilia, and sufferers often have other paraphilias with which they present. Zoophiles will not usually seek help for their condition, and so do not come to the attention of psychiatrists for zoophilia itself.The first detailed studies of zoophilia date from prior to 1910. Peer reviewed research into zoophilia in its own right started around 1960. However, a number of the most oft-quoted studies, such as Miletski, were not published in peer-reviewed journals. There have been several significant modern books, from Masters (1962) to Beetz (2002); their research arrived at the following conclusions:

Most zoophiles have (or have also had) long term human relationships as well or at the same time as zoosexual ones, and that zoosexual partners are usually dogs and/or horses (Masters, Miletski, Beetz)
Zoophiles emotions and care for animals can be real, relational, authentic and (within animals abilities) reciprocal, and not just a substitute or means of expression. Beetz believes zoophilia is not an inclination which is chosen.
A focal lung pneumatosis,  is an enclosed pocket of air or gas in the lung and includes blebs, bullae, pulmonary cysts, and lung cavities. Blebs and bullae can be classified by their wall thickness. A bleb has a wall thickness of less than 1 mm. By radiology definition, it is up to 1 cm in total size. By pathology definition, it originates in the pleurae (rather than in the lung parenchyma). A bulla has a wall thickness of less than 1 mm. By radiology definition, it has a total size of greater than 1 cm. By pathology definition, it originates in the lung parenchyma (rather than in the pleurae). A lung cyst has a wall thickness of up to 4 mm. A minimum wall thickness of 1 mm has been suggested, but thin-walled pockets may be included in the definition as well. A cavity has a wall thickness of more than 4 mm.The terms above, when referring to sites other than the lungs, often imply fluid content. Lung cysts are seen in about 8% of the general population, with an increased prevalence in older people, and are not associated with emphysema. They may be part of the aging changes of the lungs, and cause a slight decrease in their diffusing capacity. The presence of multiple pulmonary cysts may indicate a need to evaluate the possibility of bullous or cystic lung diseases. Cavitation indicates workup for serious infection or lung cancer.