My Lady has been an epileptic for nine years, ever since I adopted her at age four.
Idiopathic (true organic epilepsy) is very unusual in a dog under one year old. Usually seizures are a symptom of some underlying condition. Here are the most common:
POSSIBLE CAUSES OF SEIZURES BY AGE LESS THAN 1 YEAR OF AGE
Anomaly: hydrocephalus.
Inflammatory:
Infectious - Viral: canine distemper; parasitic; bacterial; fungal
Immune mediated
Metabolic:
Hepatic - portosystemic shunt; Autoimmune thyroiditis (early stage: TgAA
positive); Hypoglycemia; Electrolyte disorders
Toxic: Single or combination vaccines; Lead; Drug related; Other exposures
Trauma: Acute; Delayed
Degenerative: Storage disorders
Primary: Idiopathic Epilepsy ("idiopathic" = cause unknown or undetermined)
Phenobarbital damages the liver long term. It is best to use the lowest dose possible to control seizures. Add on drugs like potassium bromide and Keppra are often used to keep the dose low. I have given Lady milk thistle almost from the start and she is just now starting to show elevated liver values at age twelve. Marin is the best formulation.
I would not advise getting another Yorkie to keep him company as an epileptic dog should never be left unsupervised with another dog. Sadly, companion dogs have been known to attack and kill a seizing dog. In the wild dogs will kill an injured pack member to protect the pack from predators and this instinct can trigger an attack in your home.
If he truly has idiopathic epilepsy and not some underlying disease, it shouldn't effect his life expectancy or quality of life at all as long as his seizures can be controlled.