Cerebral Gliosis and Spongiosis in Angora goats
By Dr Mackie Hobson BSc(Agric),BVSc

1. Diseases

A number of cases involving neurological signs and deaths have been seen on different farms both in adults and young kids where the histopathology report has indicated cerebral gliosis and spongiosis.

Clinical signs

1. Young kids

These kids (month old) presented with ataxia, HQ paresis ‘Sitsiekte’. The kids could sit with their forequarters raised. They remained bright and ate. Appeared very similar to kids with polioencephalomalacia. https://www.angoras.co.za/article/polioencephalomalacia-vit-b1-deficiency-in-angora-goats

1. Adults

The adults stopped eating and drinking and were unable to walk for long before collapsing. HQ paresis. Short choppy gait, tail twitching. They remained recumbent and after a week neurological signs of muscle twitching developed before dying

Post Mortem

On histopathology both had a morphological diagnosis involving cerebral spongiosis and gliosis.

What does gliosis mean?

Gliosis occurs when the body creates more or larger glial cells (cells that support nerve cells). These new glial cells can cause scars on the brain that impact how the body works. 

Gliosis is a fibrous proliferation of glial cells in injured areas of the CNS.

What causes the reaction?

Gliosis is a reaction of the CNS to injury of the brain or spinal cord. Although subtle changes occur earlier, gliosis is usually appreciated by two to three weeks after an injury. 

What is the underlying injury?

Nearly any injury of the CNS can cause gliosis, so its presence is not diagnostic. This condition occurs after an infarct and is associated with:

• infections 
• neoplasm
• demyelinating, toxic, and metabolic diseases.

So unfortunately when seen on histopathology reports from Angora goats it does not identify the cause.

What is Spongiosis?

Called spongiosis because the resultant deterioration of neurons causes a spongelike pattern to develop in the brain tissue.

Possible causes of Spongiosis:

‘Valsiekte’, ataxia of hindquarters in lambs 2-4 months old. When driven hard, fall out, often dog sitting position, dragging back legs. Eat normally.

Resemble:

• Swayback (copper deficiency). 
• Toxicity of closantel, a halogenated salicylanilide anthelmintic,
• Chrysocoma tenuifolia (bitterbos), 
• Helichrysum argyrosphaerum (wild everlasting, poprosie), 

This causes paresis and paralysis in sheep. Signs of blindness, ataxia, circling, nystagmus, and stargazing can be seen

• Scrapie (not in South Africa) where goats will also be pruritic and scrape against walls to denude themselves.

Reference:

• Plant poisoning of livestock in southern Africa. Kellerman, Coetzer, Naude
• Myelin Vacuolation, Optic Neuropathy and Retinal. Degeneration after Closantel Overdosage in Sheep and in a Goat J.J. van der Lugta  and I. Venter
• Dr Colin Martin- Idexx laboratories
• Immunohistology of the Nervous System. Paul E. McKeever, in Diagnostic Immunohistochemistry 
• Spongiosis, optic neuropathy, and retinal degeneration in Helichrysum argyrosphaerum poisoning in sheep and a goat.J J van der Lugt , J Olivier, P Jordaan