There is more than one possible cause for persistent sores at the end of a cat’s tail. Certainly this is not something that a cat owner should ignore – not any more than you’d ignore it if your child had continuous sores on their behind.

Causes of Sores at the End of a Cat’s Tail
“A common skin ailment I see are sores at the end of a cat’s tail,” says Dr. Alison Birken, DVM, operator of a small-animal hospital in Ft. Lauderdale, FL, and co-owner of foreverfreckled.com.

Dr. Birken explains, “Many times, the owner will report that the cat licks and pulls at the tip of the tail frequently and is causing damage. Other times the cat is not licking or damaging their tail, but there just always appears to be a sore.

“First and foremost, your veterinarian must rule out infection. Many times, bacterial or fungal infections [many different kinds!] may be present, and proper diagnostic tests need to be performed to rule out infection.

“In addition, I will routinely check the cat’s anal glands and take a fecal sample to test for parasites.

“Many times there is irritation of the perianal region, caused by impacted anal glands or parasites, and the cat shows irritation by licking its tail.

“Finally, if all the above-mentioned diagnoses are ruled out, anxiety disorder may be the cause. Cats tend to over-groom when they are stressed or have anxiety.”

Additional Causes of Lesions or Sores Near a Cat’s Tail (no particular order)
• Embedded foreign object (e.g., splinter, insect stinger)
• Bite wound from another animal
• Burns
• Side effect of medication
• Overactive thyroid
• Viral infection
• Mold infection
• Eosinophilic allergic syndrome
• Urine scald (yes, believe it or not, a cat’s tail could come in contact on a regular basis with its urine)

The above list is not complete. And another thing to consider is the appearance of the “sore.” Some conditions cause more of a nodule rather than a “sore” type appearance. Some lesions or sores may also have associated fur loss. Swelling, redness and scaling may be present depending on the cause.

Can sores at the end of a cat’s tail ever be something serious?
Yes. The term “sore” is ambiguous. If the tail has lesions that are crusting, oozing or bleeding, this can mean something serious.

“Always have your pet evaluated thoroughly by your veterinarian if your cat has any lesions,” says Dr. Birken.

Unfortunately, cancer can cause what appears to be sores – that just happen to be forming near the end of the cat’s tail.

There’s nothing intrinsic about this location that gives rise to cancer. Rather, it’s where the cancer just happened to begin developing.

Remember, there are so many non-cancerous causes of sore-like lesions on a cat – that just happen to end up near the tail. Cancer is a much less likely cause of a lesion when you consider all the possible causes. However, only a veterinarian can rule out this worst-case scenario with a biopsy.

The following types of cancer can appear as a non-healing (and worsening) sore or nodule:
• Slow growing basal cell tumor; it begins as benign but may become malignant. These rarely spread.
• Hemangiosarcoma
• Squamous cell carcinoma
• Melanoma
• Lymphoma

The bottom line is that a healthy cat should not have sores, lesions or nodules near the end of its tail (or anywhere else). Even if it’s a very small spot, if it was enough for you to notice, it’s enough for your veterinarian to inspect.

Source: peteducation.com/article.cfm?c=1+2141&aid=202