I have a friend who is currently serving 36 years in the federal court system. My question is: once you are sentenced is it possible to have your sentence reduced?  And if it is possible, for what reason would they do it?  One of the witnesses that testified against my friend has written an affidavit stating that he lied about what he had testified about.  Would anyone see this as a reason to "reinvestigate" the case? And my last question is - is there federal parole anymore?

Federal sentences can be reduced by presidential commutation or pardon.  A sentence can also be reduced through a Rule 35 motion.  The prosecution uses Rule 35 motions to reward inmates who provide information that assists in the investigation and prosecution of others.

After appeal federal sentences can be attacked using a federal statute, 28 U.S.C. sec. 2255.  Succeeding in a 2255 claim requires showing that a defendant was deprived of important constitutional rights during the trial and that the deprivation resulted in a conviction.  Whether a single witness recanting his testimony would be enough to convince the government to reopen a case is hard to say.  In most cases the answer is probably no.

Parole has been abolished in the federal system for some time now.  Federal prisoners serving sentences longer than one year can earn 54 days per year off their sentence.  On a 36-year sentence your friend could earn nearly 65 months off his sentence.

Recently an unleashed dog in the back of a pickup truck jumped from the truck and attacked my cat. ... Although the owner was very apologetic and has agreed to pay the $500 vet bill, my concern is that the dog will kill again. The dog is 6 years old and the owner says this is the first time this has happened. Animal Control in my town, where the incident occurred, says they have no jurisdiction because the dog lives on elsewhere. Animal Control in the dog's hometown says they have no jurisdiction because the event occurred here. Each denies having a registry for offenders ... I have no way of knowing whether, or how many, cats the dog has killed in the past. I'm resigned to the fact that the cat is dead and if the owner does not pay, I can take him to small claims court, but is there no justice for a pet? First, it's a dangerous practice for a dog to ride in the back of a pickup truck, and second, they should at least be on a leash. Do I have any recourse to punish the owner and is it true that neither municipality has jurisdiction?

First of all, I am sorry about your cat.  I have two cats myself. 

Most pet laws are city or county ordinances so any answer depends on where exactly you live.  Even though your e-mail included your town, I do not have a way to study the local ordinances there.

If the animal control agency in the attacker's hometown won't do anything, I think a lawsuit is your only option to collect money from the owner.  Unfortunately the law of most states treat pets as property so the damages are limited to the monetary value of the pet.