TL;DR: A hot, painful lump on a cat's shoulder is likely an abscess from a bite wound and should be evaluated by a veterinarian within 24 hours. Seek emergency care immediately if your cat is lethargic or stops eating.
What could be causing a hot, painful lump and limping in my cat?
A hot, painful lump on a cat's shoulder accompanied by a limp is frequently a feline abscess. This is a pocket of infection that usually forms after a puncture wound, such as a bite or scratch from another animal. The heat indicates that your cat's immune system is fighting an active infection. Other possibilities include a localized reaction to an injection or a soft tissue injury with significant inflammation.
Is a hot lump on my cat’s shoulder a veterinary emergency?
- The urgency level for this condition is Medium.
- While a localized abscess is generally not an immediate life-threatening emergency, the pain and infection can worsen quickly.
- Contact your veterinarian for an appointment within the next 24 hours.
- Seek urgent care immediately if your cat is extremely lethargic or refuses to eat.
- The situation becomes critical if the abscess ruptures or if the infection enters the bloodstream (sepsis).
How does providing a photo or video help with the triage process?
- Providing your veterinarian with a clear, well-lit photo of the swelling and a short video of your cat walking is incredibly helpful for remote triage.
- A photo allows the medical team to see the exact location and look for 'scabs' or puncture marks that indicate a bite.
- This helps them determine how quickly your pet needs to be seen.
- Visuals help the team prepare for necessary treatments, such as drainage or antibiotics, before you even arrive.
Clinical Context (Merck Veterinary Manual)
Shoulder pain and lameness in cats can result from fractures of the supraglenoid tuberosity, mid to distal scapula, or proximal humerus due to trauma. Osteoarthritis with variable subluxation of the scapulohumeral joint can cause lameness; radiographs may reveal deep erosion of the humeral head. Soft tissue tumors can also manifest as lameness and joint swelling, with radiographs showing soft tissue swelling and periosteal reaction; pulmonary metastasis may be present. Polyarthritis, both infectious and non-infectious, can present with lameness and swollen joints, alongside systemic signs such as fever, lethargy and inappetence.
Chapter: Orthopedics, Surgery
Source: The Merck Veterinary Manual, 11th Edition (Page 1128)