“Cat nose color changes” is actually quite a tricky topic because you have to distinguish between what is normal and what requires more consideration and perhaps veterinary treatment.
Perhaps the first point to make is that when people refer to the color of a cat’s nose they must be referring to what cat breeders call the “nose leather”. This is the tip of the nose which is skin. The rest of the nose is covered by fur and therefore its color is the color of the fur. Fur rarely changes color except, for example, black cats going rusty red. Interestingly this coat color change may in fact show up on noses too. The nose going from black to brown as the cat ages. This is due to less tyrosinase. There are two pages on PoC about black pigmentation going rusty which explores the reasons in depth. Some of it might be relevant to this page (page one – page two)
I’ll focus on the tip of the cat’s nose which is a triangle of skin. Its color depends on the genetics and the cat’s coloring. The color varies widely. It can be pink (a “Dudley Nose”) or salmon colored, slate blue, black, brown and freckled (dots of dark pigment against a lighter background).
One reason for a change in the color of a pink colored nose leather would be squamous cancer of the nose (and possibly the ears as well). The lighter color makes the skin more susceptible to being burned by potentially dangerous ultra-violet radiation.
A pink nosed cat might develop a white nose due to anaemia. Anaemia is a symptom of a low number of red blood cells in the blood for a range of reasons.
However, some cat owners say that the pink nose of their white cats or bicolor cats goes white when they rest. This is probably a reflection of blood flow in the skin of the nose. Perhaps when resting the flow reduces and the vessels shrink while when active more blood flows through the nose turning it pink. As you can see there is a fine line between possible health problems and what is normal.
Dr Becker states that there a such a thing as “winter nose”. This is a fading of nose color during the colder months. This is possibly due to the nose becoming cold which causes the minute blood vessels in it to shrink which removes some of the healthy coloring.
Black spots can appear on the nose (and eyelids) like freckles as mentioned. In other words rather than being born with spots on the nose they develop. The is called lentigo simplex and is referred to on this page in some detail.
Sickness can cause a cat’s nose to go pink from a darker color. Also, if the nose is scratched this removes the pigment which is revealed when he scab falls off and then the pigment comes back.
Dr Becker says that continual use of plastic bowls for feeding can cause the nose to lighten over time. The reason? A sensitivity to plastic by certain individual cats.
Some medical reasons (source Vetinfo and Michael) for nose color change are:
- Jaundice (liver failure) the skin generally turns yellow
- Bruising – the nose has a bluish bruised hue
- Crusty nose on Bengal cat. This is called ‘Bengal Nose‘. Probably caused by a defective immune response
- Allergy causing skin to become darker
- Tumor – but this would probably be fairly obvious
Hope this helps a bit. The bottom line is deciding if a change in color is health related. Other symptoms may provide the clue.