TL;DR: Spinal muscle wasting causes a cat's back to feel bony and often signals an underlying systemic illness. You should schedule a veterinary visit within the week, or sooner if the cat is lethargic or loses their appetite.
What is spinal muscle wasting in cats and why does it occur?
Muscle wasting along the spine, often referred to as sarcopenia or muscle atrophy, occurs when a cat loses the lean tissue that normally cushions the vertebrae. You may notice your cat’s back feels suddenly "pointy" or "bony" to the touch. This isn't just a sign of getting older; it is frequently a symptom of the body being in a catabolic state, where it breaks down muscle for energy or due to an underlying systemic illness.
Is it an emergency if my cat has visible muscle wasting?
- The urgency level for visible muscle wasting is classified as Medium.
- While this is rarely a sudden medical crisis like a trauma or a blockage, it is a serious indicator of an internal health issue.
- You should schedule a veterinary appointment within the week.
- If the muscle loss is accompanied by a sudden loss of appetite, hiding, or extreme lethargy, you should seek care sooner.
How does taking a photo of my cat's back help with veterinary triage?
- Taking a clear photo or video from a "bird's eye view" (looking down at your cat's back while they are standing) is incredibly helpful for triage.
- It allows veterinary professionals to visualize the degree of atrophy and assign a Body Condition Score.
- These images serve as a vital baseline to track whether your cat is gaining or losing more weight after treatment begins.
Clinical Context (Merck Veterinary Manual)
Feline hypokalemic polymyopathy is a generalized metabolic muscle weakness disorder in cats secondary to hypokalemia associated with excessive urinary depletion or inadequate dietary intake, leading to muscle cell membrane hyperpolarization and subsequent weakness. Clinical signs include generalized weakness and ventroflexion of the neck. Spinal cord diseases, including neoplasia such as lymphoma (most common in cats, often with feline leukemia virus), can also cause muscle atrophy along the spine due to nerve damage; diagnosis relies on radiography, myelography, CT, or MRI.
Chapter: Neurology, Musculoskeletal, Metabolic/Nutritional
Source: The Merck Veterinary Manual, 11th Edition (Page 1201)