Air travel for dogs has long been a hotly debated topic among pet owners. While some swear they would never ship their beloved pets like cargo, others counter that it sometimes simply cannot be avoided.

Airlines cater to animal-friendly travel with special programs, ranging from JetBlue's JetPaws to United Airlines' PetSafe. In October, the Department of Transportation ruled airports that service more than 10,000 passengers annually must install one animal relief area in each terminal after security, and New York City's John F. Kennedy International Airport is opening a "Pet Oasis" in the ARK, a $65-million “terminal for animals."

But even with modern advances, accidents do happen. They're very rare, with 23 deaths, 20 injuries, and zero losses reported in the U.S. from January to October 2016 (the last month for which data is available), according to the Department of Transportation. That's a small number of the estimated 2 million pets that travel on commercial flights each year.

But as any animal lover knows, it only takes one tragic incident to turn a family upside down.

Take Kathleen Considine, a Portland-based bartender who has been making headlines after her Facebook post detailing the death of her 7-year-old golden retriever, Jacob, went viral. Jacob had been traveling from Detroit, Michigan, to Portland, Oregon, when his one-hour layover in Chicago turned into 20 while United Airlines waited for a plane that could fit his crate.

The airline said Jacob showed "no signs of distress" while in their care, but he died on the emergency vet table hours after landing from gastric dilatation and volvulus syndrome, a bloating condition that causes the stomach to dilate and twist into an abnormal position, and is commonly caused by stress.

As the issue comes to the forefront yet again, we asked Brian Brophy, MVB, a veterinary surgical resident at the University of Pennsylvania, what dog owners need to know before putting a pet on a plane.

What are signs a dog may show after a flight that signal it needs to be treated by a vet?

General signs of distress include lethargy, vomiting, diarrhea, and loss of appetite. If the dog collapses or shows signs of difficulty breathing (excessive panting, purple or blue-tinted gums), that's an emergency and the dog should be evaluated immediately.

How long of a flight can dogs safely handle?

Every situation is a little bit different. A lot of the determination about how long of a flight animals can handle depends on the environment they're traveling in. Pets that are small enough to travel in the cabin are obviously able to be monitored more closely by their owners, and are in a climate-controlled setting.

Extreme heat and cold are usually the most significant risks to animals when they travel in cargo, so it's probably ideal to avoid flying during seasonal extremes if you can. If it can't be helped, shorter trips for animals in cargo are preferable.

Would you advise owners avoid flights with layovers for their pets?

A lot of airports now have areas where you can walk your dog safely during layovers without having to exit security. If you are traveling a long distance, it may be a good idea to check ahead at your layover airport to see if this is the case. Plan to budget yourself a little extra time for checking in on your pet and/or walking them, if you're going to have a layover.

What precautions should pet owners take before putting their animals on a plane?

Talk to your vet in advance, since each individual pet will tolerate flying a little bit differently. Sedatives and anti-anxiety medications can be very helpful but must be used carefully, especially if your pet has any underlying health conditions.

If your pet takes medications for any other health problems, work out a plan ahead of time to ensure they're receiving them at appropriate times.