Scottish veterinarians are perplexed by a mysterious new illness that is causing their feline patients to walk like robots.
In a report published in the Journal of Feline Medicine and Surgery, a group of veterinary scientists studied 21 cats exhibiting peculiar symptoms after being diagnosed with an infection of the central nervous system (CNS).
The team describes their medical findings after closely examining cats brought to the Strathbogie Veterinary Centre and the Morven Veterinary Practice, both in Scotland, between 2001 and 2010. All animals suffered from lymphohistiocytic meningoencephalomyelitis, a type of inflammation of the brain. However, the slow disease progression and distinctive neurological symptoms presented by the cats suggest that a different, previously unreported disease agent might be at work.
The affected cats displayed signs of disorientation and a dulled mental status. The most representative clinical symptom of the disease is a rigid and extended tail, coupled with a spastic and uncoordinated gait. The mean age of disease onset was 9 years old, which is much older than previous known cases of CNS infection. Furthermore, in the past CNS-related diseases progressed within several weeks. However, several months can pass before symptoms of this new illness become observable. As the disease progresses, neurological symptoms worsen. Although the disease does not cause death, the quality of life decreases to a point where veterinarians suggest putting the cats to sleep, as a humane alternative.
Since almost nothing is known about the disease agent, it has been impossible to cure the cats. Vets attempted to treat the infected animals with antibiotics, steroids, and vitamins, but all proved unsuccessful.
Immunohistochemistry ruled out 15 different pathogens, however scientists discovered elevated levels of a protein known as interferon-inducible Mx in all 21 cats. This protein is expressed mainly in immune cells and astrocytes (a type of cell found in the brain and spinal cord). The researchers utilized evidence from dogs suffering from inflammatory encephalitis that showed that Mx protein expression was associated with virus and fungi infections. Further, histological evidence was able to exclude non-viral organisms as the causative agent. Although this would suggest a viral etiology, an infectious or environmental trigger still needs to be considered at this stage in research.
Additionally, all cats were avid outdoor hunters of rodents and birds, and all originated from a rural area in northeast Scotland, between Iverness and Aberdeen. Some scientists hypothesize that the disease is limited to Scotland and is somehow spread from prey to predator. However, there is not yet enough information on the etiology of the disease to come to any definite conclusions.
A similar but unrelated disease, termed “staggering disease”, has been reported in cats from Sweden and Austria. However, these animals did not exhibit the peculiar stiff tail and ataxic gait that is so indicative of this mysterious illness.