My Male Chihuahua Has Green Goop Coming Out Of His Penis, What Do I Do?

Green discharge from the penis of dogs can be due to many conditions that should be investigated by the vet. Inflammation of Penis and prepuce is major cause of green discharge from dog penis. This inflammation can be due to

1. Bacterial infection
2. Injuries
3. Tumors
4. Constriction of the prepuce

When dogs have this green discharge, they usually lick their penis, shake and go for urination frequently. Diagnosis involve blood and urine tests. Usually antibiotics are recommended to treat infection. So, take your dog to vet.