Polioencephalomalacia: Vit B1 deficiency in Angora Goats
By Dr Mackie Hobson BSc(Agric),BVSc

UPDATED JUNE 2020

Polioencephalomalacia (PEM) - caused by Vit B1 (Thiamine) deficiency simply literally means softening of the brain.

It is a disease that is seen more commonly in Angora kids grazing lucerne lands or fed concentrates especially if containing molasses.

It does however also occur in adult Angora goats.

The softening of the brain (laminar necrosis of the cerebral cortex) is through hypoxia (lack of oxygen) due to substances that block thiamine (Vit B1) which is essential to neuronal carbohydrate metabolism.

Below photo Angora kids unable to stand or raise their hindquarters

The disease can be seen under the following conditions:

• Goat kids are very prone to thiamine deficiency as the rumen is not fully functional for the first year. Kids who have just begun consuming high concentrate rations or grazing lush pasture are most susceptible.
• Acute rumen acidosis can result in bacterial-mediated thiamine destruction in the rumen.
• Presence of thiaminase producing bacteria in the rumen such as clostridia, which is often associated with carbohydrate rich diets, will also result in reduced thiamine production
• High levels of sulphates (Sulpher) in the diet such as goats grazing lucerne or fed concentrate diets that contain molasses.
• Some water sources are also high in sulphur.
• Any illness or condition that leads to a goat not eating can cause the rumen to function poorly, resulting in a drop in B vitamin production.
• Any change in diet may also lead to rumen function issues as it takes the rumen about 7 to 10 days to adapt to the diet change
• Certain deworming drugs such as Levamisole and ivermectin as well as drugs such as amprolium and metronidazole can cause the condition.
• Mouldy hay or feed also leads to poor rumen function (Mycotoxins from Aspergillus, Claviceops)
• Poisonous plants such as solanum, sorghum and bracken fern can predispose the condition.
• Certain pesticides such as carbaryl, chlorinated hydrocarbons

Below photos of Angora kids unable to stand or raise their hindquarters

How do goats get Vit B1 (Thiamine)?

Do I need to supplement?

B vitamins are not necessary supplements in the diet of a healthy goat.

In fact, B vitamins are not obtained by ingestion of feeds at all. Goats manufacture B vitamins in the rumen through micro-organisms during the digestion process which they absorb. The bacteria in the rumen produce enough thiamine for an animal’s needs. However, under certain conditions thiamine production may decrease or available thiamine may be destroyed leading to a deficiency and the appearance of clinical signs.

Keep in mind the predisposing factors mentioned above as there may be times when you do need to supplement Vit B1.

What clinical signs are seen?

• Depression
• Aimless wandering
• Grinding teeth
• Head pressing
• Weak back legs
• Staggering
• Short choppy hindquarter gait
• Star gazing
• Muscle tremors
• Circling
• Blindness
• Nystagmus – flickering of eye.
• Collapse, unable to stand and death

The Neurological clinical signs resemble those seen in Heartwater, Pulpy Kidney and cumulative bufadienolides poisoning causing ‘Krimpsiekte’.

In the Video of the kids early clinical signs of Thiamine deficiency include a short choppy HQ gait and twitching tail. The video of more advanced signs the kids are unable to stand and may try crawl or the drag their hind limbs while in a sitting position.

The signs may be confused with the ‘Floppy kid syndrome’ https://www.angoras.co.za/article/floppy-kid-syndrome

Treatment

• Make sure you treat with Vit B1 (Thiamine) as the other Vit B’s will not help!
• Ensure the concentration is high at least 100mg/ml.
• Vit B1 (thiamine) intramuscular injection (10 – 20 mg/kg body weight) given every three hours for a total of five doses. Early cases respond within 6 to 8 hours with complete recovery in 24 hours. Goats not recovered by 72 hours will usually not fully recover. However under veterinary supervision I have treated a kid with daily injections for a week which made a full recovery (see video)
• A goat will not overdose on an injection of B vitamins. The excess is expelled through urination.
• The administration of probiotics assists with proper micro-organism balance in the rumen.

Post Mortem

A ram showing neurological signs was humanely euthanased and on post mortem examination and histopathology Polioencephalomalacia (PEM)/Cerebrocortical necrosis (CNN) was diagnosed. (Histopath Vetdiagnostix Dr Rick Last)

Local; meningeal haemorrhages with haematoma formation. Segmental zones where the cerebral cortex is more eosinophilic and undergone collapse being narrow and reduced in thickness with nuclear pycnosis and hyperchromasia of the neurons of the deeper lamellae.  Prominent oedema with widening of peri-neuronal spaces around the shrunken necrotic neurons.

Photo: Brain with haemorrhages and haematoma clearly visible.

Dr Mackie Hobson (SAMGA vet)