Aggression, irritability, fear and anxiety can also be caused by subtle deterioration of the brain. Sometimes an affected old dog will stand staring into a corner for hours, until someone helps him. There has been great progress in recent years in veterinary treatment options for cognitive dysfunction syndrome. The first step is a complete physical examination and some laboratory tests to rule out other diseases. Adrenal gland disorders can also cause panting, weakness, decreased responsiveness to owners, and changes in the sleep-wake cycle.
Hypothyroidism can cause dullness, lethargy and aggression.
Arthritis and other similar painful joint and spine disorders can cause reluctance to go outside for urination and bowel movements. Cataracts and several other eye diseases can interfere with vision and cause apparent confusion. Liver disease and kidney failure can cause dullness, confusion, and may also affect the way drugs are metabolized, and change the dose required. There are several other similar drugs that increase dopamine and other nerve impulse transmitters, increase blood flow and oxygen, decrease blood clotting, and decrease levels of toxic free radicals. These are not approved for use in dogs, but many have been studied and are commonly prescribed by veterinarians for dogs and cats.