Patients may have apparent enophthalmos (affected eye looks to be slightly sunken in) but this is not always the case. The ptosis from inactivation of the superior tarsal muscle causes the eye to appear sunken in, but when actually measured, enophthalmos is not present. The phenomenon of enophthalmos is seen in Horners syndrome in cats, rats, and dogs.Sometimes there is flushing on the affected side of the face due to dilation of blood vessels under the skin. The pupils light reflex is maintained as this is controlled via the parasympathetic nervous system.In children, Horners syndrome sometimes leads to heterochromia, a difference in eye color between the two eyes. This happens because a lack of sympathetic stimulation in childhood interferes with melanin pigmentation of the melanocytes in the superficial stroma of the iris.In veterinary medicine, signs can include partial closure of the third eyelid, or nictitating membrane. Causes
Horners syndrome is usually acquired as a result of disease, but may also be congenital (inborn, associated with heterochromatic iris) or iatrogenic (caused by medical treatment). In rare cases, Horners syndrome may be the result of repeated, minor head trauma, such as being hit with a soccer ball.
Pontiac fever  is an acute, nonfatal respiratory disease caused by various species of Gram-negative bacteria in the genus Legionella. It causes a mild upper respiratory infection that resembles acute influenza. Pontiac fever resolves spontaneously and often goes undiagnosed. Both Pontiac fever and the more severe Legionnaires disease may be caused by the same bacteria, but Pontiac fever does not include pneumonia. Cause
Species of Legionella known to cause Pontiac fever include Legionella pneumophila, Legionella longbeachae, Legionella feeleii, Legionella micdadei, and Legionella anisa. Sources of the causative agents are aquatic systems and potting soil. The first outbreak caused by inhalation of aerosolized potting soil was discovered in New Zealand in January 2007. A total of 10 workers at a nursery came down with Pontiac fever. It was the first identification of L. longbeachae. Pontiac fever does not spread from person to person. It is acquired through aerosolization of water droplets and/or potting soil containing Legionella bacteria. Diagnosis
Epidemiology
Pontiac fever is known to have a short incubation period of 1 to 3 days. No fatalities have been reported and cases resolve spontaneously without treatment. It is often not reported. Age, gender, and smoking do not seem to be risk factors. Pontiac fever seems to affect young people in the age medians of 29, 30, and 32. Pathogenesis of the Pontiac fever is poorly known. History
Pontiac fever was named for Pontiac, Michigan, where the first case was recognized.