Portosystemic Shunt (PSS) is an inherited or acquired condition in dogs and cats when the blood flow is diverted from the liver. As a result, the liver fails to remove toxins from the blood. The accumulation of toxins in the blood causes neurological and other diseases. Dogs with PSS have a small but otherwise healthy liver, large kidneys, and stones in bladder or kidneys. Shunts are significantly more likely to be found in female than male dogs and cats. The disease is commonly seen in the Yorkshire Terrier, Maltese, Miniature Schnauzer, Lahasa Apso, Shih Tzu, retrievers, Irish Setter, and Wolfhound breeds, as well as Himalayan and Persian cats. The exact causes of this disorder are unknown.
Signs of ortosystemic shunt are usually found in young puppies and may include loss of appetite, vomiting, diarrhea, pica, depression, lethargy, frequent urination, excessive thirst, weakness, poor balance, vision loss, seizures, and intolerance of protein-rich food. Currently, the condition cannot be managed with diet only and surgery is the best option. Many dogs become normal and require no medication or diet control providing the surgery did not have any complications and was performed before the atrophy of the liver.