A highly irritable cat may even cut its face with the claw of its hind foot if over-zealously scratching the back of its head. Treatment
The cat should be taken to a veterinarian. The most suspected cause of skin problems in cats will be fleas. Other causes of over-grooming are not as easily ascertained. As household antiseptics are known to be toxic to cats, veterinary antiseptics for cats can be used to treat open sores, if they do occur. Sores can also be treated with cream, oral or injected anti-inflammatories, however if the problem continues to recur it may be more cost effective to subject the cat to laboratory testing early on. It may be difficult to keep a clean dressing on a cats belly, and an anti-lick collar is adequate to let the wound heal. If an anti-lick collar is used, a soft anti-lick collar is less cumbersome, although they are less durable. If the cat wears a plastic anti-lick collar, it may use the edge of the collar to grind against existing wounds, making them worse. A soft anti-lick collar will become less effective as it is kicked out of the shape by the cats hind leg, and will need prompt replacement. The cat can sanitize the wound if the collar is removed for daily short periods of time, also giving the cat an opportunity for an overall grooming. Scratches and wounds can heal completely using this method.
The Lewy bodies typical to PD are not seen in Mn-induced parkinsonism.Agent Orange may be a cause of parkinsonism, although evidence is inconclusive and further research is needed.Other toxins that have been associated with parkinsonism are:

Annonaceae
Carbon monoxide
Carbon disulfide
Cyanide
Ethanol
Hexane
Maneb/Mancozeb
Mercury
Methanol
MPTP
Paraquat
Rotenone
Toluene (inhalant abuse: "huffing")

Vascular
Binswangers disease (subcortical leukoencephalopathy)
Vascular dementia (multi-infarct)

Other
Chronic traumatic encephalopathy (boxers dementia or pugilistic encephalopathy)
Damage to the brain stem (especially dopaminergic nuclei of the substantia nigra),basal ganglia (especially globus pallidus) and the thalamus. Hypothyroidism
Orthostatic tremor
Paraneoplastic syndrome: neurological symptoms caused by antibodies associated with cancers
Rapid onset dystonia parkinsonism
Autosomal recessive juvenile parkinsonism

Society and culture
In the United States, the 2021 National Defense Authorization Act (NDAA) added parkinsonism to the list of presumptive conditions associated with Agent Orange exposure, enabling affected service members to receive Veterans Affairs disability benefits. References
External links

GeneReviews/NIH/NCBI/UW entry on Perry syndrome
GeneReviews/NCBI/NIH/UW entry on X-Linked Dystonia-Parkinsonism