If you're allergic to cats or dogs, life can be pretty tough. Sometimes all you want to do is snuggle up with a puppy, but then, suddenly, you're sneezing and wheezing - it's no fun.
An allergic reaction comes from your immune system overreacting to things like pet dander - the microscopic flakes of dead skin and hair they shed, or their saliva. But pets can get allergies, too. And while it is rare, dogs and cats can even be allergic to each other, or to us - more specifically, to human dander.
No matter who's sneezing at whom, the basic science behind allergies in pets is the same as in people. Basically, the immune system confuses a harmless allergen, like cat dander, for a dangerous invader, and attacks. It releases antibodies, which are proteins that detect and bind to the allergen, then sends a signal to other immune cells to release inflammatory molecules like histamine. Inflammation irritates the sensitive tissues that line the insides of your nose, respiratory system, eyes and skin - and that makes you all sneezy and itchy and eye-watery.
Just like us, our pets can be allergic to a variety of things, like pollen, grasses, mold and food. One study from 2014 looked at about a 100 dogs that were having an allergic reaction to something, and found that about half of them were sensitive to house dust and dust mites - the little critters that eat dead skin. But that's not because dust is mostly made of human skin - if you've heard that before, it's a common misconception. House dust is mostly made of dirt that comes in through open doors or windows, or on the bottom of your shoes. But you do shed some dead skin, and some experts think there are rare instances of pets that are specifically allergic to human dander. 
When a dog is allergic to something, whether it's you or dust mites, they often develop a condition called atopic dermatitis - or itchy, red, swollen skin. Cats can also get itchy skin or can lose patches of fur. Their allergies are also likely to cause inflammation in their respiratory tracts, which makes them sneeze and cough. It's common enough that feline asthma affects about 1% of the cat population.
Luckily, vets are great at diagnosing and treating allergies, so there's no need to say goodbye to your furry friend. To test for allergies, vets can do blood tests that measure the amount of antibodies in the blood, or a skin test, which is more sensitive and has quicker results. For the skin test, the vet scrapes or injects a small amount of allergen on or in the skin to see if it causes a reaction. If it does, they can treat the allergy with shots or oral medication. Just like in humans, these treatments expose animals to small amounts of an allergen, slowly increasing the concentration over time, so their immune system can build up a tolerance and stop freaking out. So, if you notice your pet breaking out in a rash or sneezing after you cuddle them, they might be allergic to you - but it's most likely some other allergen, like pollen or dust; because even for our furry friends, allergies can be a little "ruff".
If you have allergies that prevent you from cuddling up to a cute dog or cat, you might instead distract yourself by cuddling up to a good book. But what if you're short on time, or want to know if a book is really up your valley before you dive in? Well, Blinkist is a new app that lets you cram the world's bestselling nonfiction books into your brain in 15 minutes. It basically gives you a superpower by framing a book's key concepts so that you get the gist of all these books you just don't have time to read. Blinkist titles, or Blinks, are presented both in audio and text format, so you can listen on your walk to work or read them on the rise home using apps for iOS and Android devices, or their website. Over 2,200 books are already on Blinkist, and 40 new titles are added every month. I've been thinking of reading The Immortal Life of Henrietta Lacks, and checking it out on Blinkist first was a great way to vet the story. And Blinkist is offering an exclusive deal for our viewers, so, to support SciShow and receive 20% off a new subscription, click the link in the description. Anyone can try out Blinkist for free, but we think you'll find the full subscription totally worth it.