My cat sneezed blood after a respiratory infection. Should I worry?

Since this has bene going on for a while, I would get it checked by your vet as soon as possible. It could be a cold, he could have sneezed some particle of foreign material up into his nasal cavity, he could have a polyp in his nose, there's no way to know for sure without an exam with your vet. The greenish tinge to the discharge may mean he already has an infection going on. Your vet will do an exam, possibly lab work and/or x-rays to determine what's going on and based on these results will be better able to tell you what's wrong and give you treatment options.

Poor cat. Over 90% of cats with acute sneezing discharge are infected with herpesvirus and calicivirus. These viruses are usually exposed to cats when they are young and cats seems to recover from them but they continuously cause irritation, erosions, and inflammation of the upper respiratory tract (nasal passages) over time which can lead to mild nose bleeds. However there is also a possibility that your kitty could have a coagulation problems that is causing the bleeding as well. Therefore it is best to get kitty seen by your veterinarian for a coagulation profile in case kitty needs more extensive treatment to resolve this. If kitty is negative for any bleeding disorders or any other potential causes of nose bleeding (i.e. fungal, allergic, etc), then the extent of treatment will most likely be 1) Anti-viral medication (Lysine-availlabe over the counter at your local pet store or at your vet clinic), 2)Antibiotics- to treat any secondary infections present, 3)Steroid or NSAID therapy to help ease inflammation of the nasal turbinates. I would recommend scheduling an appointment with your cat's veterinarian soon to get the proper testing and treatment your cat needs for his care.

Batman may have some residual inflammation in the nose from the previous infection. I would recommend using a supplement called duralactin with lysine to help treat a viral infection such as herpes virus. This could have been the cause previously but could be lingering and causing continued symptoms. I would also recommend an anti inflammatory drug short term and see how he does. I hope this helps guide you in the right direction. Please let me know if you have any other questions or concerns.

This is probably an upper respiratory infection. it's very common in cats and is very contagious to other cats as well. It is treated with oral antibiotics for about 2 weeks. if left untreated many cats will end up blind or even die from the disease. I advise going to your vet asap to start the treatment right away.

As long as he is still eating and able to sleep comfortably then i would not be overly concerned. Bathing his nose with saline and cotton wool can help free any mucus and make breathing a little easier. If symptoms worsen or he starts breathing with his mouth open I would seek an emergency appointment

Sneezing is a very vague sign in the sense it only means there is irritation to the nasal passages. So you are completely right in not jumping to the conclusion of an infection. It is more likely due to an irritant such as dust or pollen, or even cold air annoying the sensitive tissue. Do keep an eye as it could be the start of a touch of cat flu, but these things tend to be viral anyway.

I do think it would be a good idea to see the vet but it can sometimes be very difficult to find the source of the blood in a situation like this. A sneeze is possible but you would probably also see some nasal discharge. If it is from urine I would expect that a cat would be visiting the litter box frequently or straining to urinate. Toenails and ears can also bleed if they are injured. Since blood in the urine in particular can be very serious I'd recommend seeing a vet sooner rather than later even if both cats seem fine otherwise.