FCV-Associated Limping Syndrome in Cats: Recognising Acute Shifting Lameness

A cat that suddenly becomes lame in one limb and then appears painful in another can present a diagnostic challenge, particularly when lameness develops around an episode of fever or acute respiratory and oral disease. In feline calicivirus (FCV) infection, this shifting pattern is a recognised clinical presentation and can also occur following vaccination with some modified-live FCV vaccines^[1]. 

A Lameness Pattern That Can Move Quickly^[1] 

FCV-associated limping syndrome is characterised by acute, transient and shifting lameness, often accompanied by fever. 

The clinical pattern itself is important. Lameness may initially involve one limb and then shift rapidly to another. In natural infection, it can be severe, which may make the presentation appear more concerning than its eventual clinical course suggests. 

The timing can also provide a useful clue. Limping syndrome may develop a few days or weeks after the acute oral or respiratory signs of FCV infection. 

What Happens in the Joints?^[1],[2] 

The underlying mechanism is not completely clear. Acute synovitis has been documented, with thickening of the synovial membranes and an increase in synovial fluid in affected cats. 

Immune complexes are thought to contribute to the pathogenesis. At the same time, FCV has been isolated from affected joints. Therefore, the available findings do not support reducing the syndrome to a single clearly established mechanism. 

For clinical assessment, the combination of acute onset, fever, and rapidly shifting lameness is more informative than assuming that every painful joint represents a persistent orthopaedic disorder. 

Infection or Vaccination? 

The syndrome is associated not only with natural FCV infection but also with some modified-live FCV vaccines^[1]. 

However, temporal association with vaccination does not automatically establish that the vaccine strain caused the lameness. In some reported cases following vaccination, field FCV strains different from the vaccine strain were detected, making vaccination incidental in those cases^[1]. 

Experimental oronasal infection with FCV vaccine strain 255 produced mostly mild lameness in 3 of 10 cats^[1]. This finding supports the possibility of vaccine-associated lameness but does not establish that every post-vaccination episode has the same cause. 

What Should the Clinician Expect?^[1] 

One of the most useful features of naturally occurring FCV-associated limping syndrome is its short clinical course. Despite potentially severe lameness, full recovery usually occurs within 24–48 hours without treatment. 

Where inflammation and pain are clinically significant, NSAIDs can be useful for reducing inflammation and pain. 

The rapid resolution is therefore an important part of the clinical picture. A cat with severe shifting lameness that improves substantially within this short period fits the described FCV-associated syndrome better than a presentation characterised by persistent, progressive lameness. 

Clinical Bottom Line 

When fever accompanies acute, severe lameness that shifts rapidly between limbs, FCV-associated limping syndrome should be considered, particularly when oral or respiratory signs preceded the lameness. Acute synovitis has been documented, but the precise pathogenesis remains uncertain. The syndrome can follow natural infection or occur after some modified-live FCV vaccines, so the timing of vaccination alone should not be treated as proof of causation. In natural infection, recovery commonly occurs within 24–48 hours, with NSAIDs potentially useful for controlling inflammation and pain.

References:

1. Hofmann-Lehmann R, Hosie MJ, Hartmann K, Egberink H, Truyen U, Tasker S, Belák S, Boucraut-Baralon C, Frymus T, Lloret A, Marsilio F. Calicivirus infection in cats. Viruses. 2022 Apr 29;14(5):937. https://www.mdpi.com/1999-4915/14/5/937
2. Lanave G, Buonavoglia A, Pellegrini F, Di Martino B, Di Profio F, Diakoudi G, Catella C, Omar AH, Vasinioti VI, Cardone R, Santo G. An outbreak of limping syndrome associated with feline calicivirus. Animals. 2023 May 26;13(11):1778. https://www.mdpi.com/2076-2615/13/11/1778