Friday, 8 May 2015

All About .....Poisonous Plants

To complete my current 'Paddock Knowledge' set of blogs today I'm going to cover poisonous plants.  These are plants that could quite easily be growing in your field and have the potential to cause illness and even death to your horse if eaten.  These are plants found in the UK.
The way each of these plants is dealt with can also be important as some are just as poisonous when dead.

This tends to b avoided by horses as it has a bitter taste.  However, wilting or dead plants are more palatable.  The toxins in ragwort can cause liver failure and death, it is a slow killer .  Poisoned horses lose weight, get extreme sunburn and go blind.  They will eventually collapse. 

It is essential that hay is free from ragwort. 

Ragwort thrives on poor grazing and is easy to identify in its second year when the yellow flowers are obvious.  In the first year it simply produces a dense rosette of leaves, which is more difficult to spot.
Ragwort must be dug up and burnt. Ensure you remove all the root otherwise it will re-grow next year.  Do not let the plant seed as you will have many more plants the following year!

Less likely to be found in your paddock and horses tend not to eat foxgloves but they are more palatable if contained in the hay.  Just 100gms can be fatal after only a few hours.  Symptoms include diarrhoea, abdominal pain, convulsions and heart failure.

Deadly Nightshade (Belladonna)
Foliage and berries are extremely toxic.  This does not normally cause death but can cause narcosis, dilation of the pupils and convulsions.

This is a weed which is commonly found in pasture and it is poisonous to all livestock.  The hollow stem is spotted or streaked with purple on the lower half.  The toxins cause respiratory paralysis leading to death.  Remove and burn Hemlock during the Spring.  Both Hemlock and Cowbane (below) can be confused with Cow Parsley.

Cowbane (Northern Water Hemlock)
Growing in wet meadows, the roots are the only toxic part and it is not common for horses to eat this part of the plant.  As with Hemlock the stems have red/purple spots and white flowers, it can grow to 2 metres high.  Affecting the nervous system it  will cause convulsions, tremors, colic and dilated pupils.  

Poisonous when eaten fresh but only if eaten in large amounts.  They have an unpleasant taste so horses usually avoid them.  Dried buttercups in hay are harmless.  They will cause blistering and ulcers in the mouth which will obviously then deter a horse from eating more.  However, if there is no other food available a horse  will continue to eat them and eventually they will cause a life threatening seizure.
These also spread rapidly, control them with an appropriate weed killer but remember to keep any horses out of the pasture until a good rain shower has washed the leaves and/or for the time the manufacturer recommends!

Often found in gardens and as hedges. The berries, bark and leaves are lethal if eaten.   Just 0.5kg can be fatal.  Symptoms are trembling, muscle weakness, slow or irregular heartbeat and convulsions.  The heart muscles are slowly destroyed and this eventually leads to a heart attack.

Oak - Acorns
Acorns are loved by many horses and can lead to severe colic if eaten in large quantities.  Do not allow your horse access to acorns by either removing the acorns or ideally fencing the area around the tree.  Leaves and acorns are poisonous.  Other symptoms are diarrhoea, lack of appetite, depression and lethargy.

The toxin affects the gastro-intestinal tract and the nervous system.   All of the tree is poisonous if ingested; to humans and animals!  Symptoms include, colic, drowsiness, frothing of the mouth, unequally dilated pupils, diarrhoea, convulsions, coma, death.

Popular as a hedge.  Causing rapid pulse and respiration rate.  Other symptoms include: staggering, diarrhoea, convulsions and paralysis.  A horse can die within 4 - 48 hours if they do not receive veterinary attention.

An evergreen shrub, popular as hedging in gardens, it produces white flowers.  Leaves and berries are poisonous due to the Cyanide the plant contains.  It can cause breathing difficulties and fatigue.

Unlikely to be found in a paddock but popular in gardens.  Symptoms include digestive disorders, difficulty standing and breathing a weak pulse and the horse may collapse.  Very small quantities can cause a horse's respiratory system to fail.

These have several different coloured flowers and can cause digestive upsets, general weakness and a rise in temperature.

Linseed (Flax)
Growing to about 1 metre the plant has brown seeds.  Once boiled (see my feed blog) these seeds are no threat to a horse.  Untreated they are poisonous!  Symptoms of linseed poisoning include: rapid heart beat, breathing difficulties, excessive salivation, difficulty in standing and coordination. 

Lily of the Valley
Small plant with small white bell shaped flowers and broad leaves.  Symptoms include digestive disorders and a rise in heart rate!

St John's Wort
This plant can cause photosensitivity (sensitivity to sunlight) which causes the horse to become sore, itchy and sensitive when the skin is exposed to sunlight.

Height and flower colour varies.  All parts of the plant are toxic.  Symptoms include breathing and digestive problems, colic, diarrhoea, coordination and general weakness, also difficulty in standing.

Hemp Nettle
It looks quite a lot like mint but has small red flowers and is found throughout the UK.  It causes depression, digestive upsets and a lack of appetite.

This is common in pastures and is toxic when fresh and dried.  It can grow to 1.5 to 2 metres high and the whole plant is poisonous.  Causing the destruction of vitamin B symptoms include lethargy, weakness, un-coordination and a lack of appetite. When eaten over a long period of time it will cause heart and kidney damage.

Bright red flowers with black seeds.  Symptoms of poppy poisoning include increased breathing rate and excessive salivation.

Bracken Fern
This is found on moors and often in well-drained pastures.  Most horses will avoid it unless there is nothing else to eat.  It causes a deficiency in vitamin B1 and can cause lack of appetite, and disorders of the nervous system.  It will kill if eaten repeatedly over a long period.  Symptoms are frothing at the mouth, bloating, diarrhoea and breathing problems.

Very rare in the UK but possibly the most poisonous so important to be aware of.  All parts are poisonous.   Also poisonous to humans!  Symptoms include skin irritation, depression and breathing difficultis.

In the last 2 years the seeds of the sycamore tree (and box elder) have been linked to Atypical Myopathy.  The sycamore tree is common in the UK and in paddocks.  Research is ongoing but with the disease so rapid and devastating it is VITAL that you are aware of this tree and its seeds (helicopter seeds).  The clinical signs of Atypical Myopathy include: muscular stiffness, reluctance to walk, difficulty standing, muscle tremors, sweating, depression, high heart rate, dark urine and breathing difficulties.  Many horses have been found dead in their paddocks.  Minimise your horse's exposure to these trees and as with the oak tree put a fence to prevent your horse's access to the seeds. However, they are easily carried by the wind from neighbouring properties!   It is thought that the seeds and saplings are only eaten when the horse has little other food available - but this may be a bit too risky!

Apart from checking the field/paddock where your horse grazes regularly, I think one of the greatest things to remember is to get hay from a reputable source.  If buying from a farmer it is essential that they are aware of these plants and do not allow them to grow in the fields which they cut for hay.  Poisonous plants are more difficult to identify in the hay but you should still check.

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Until next time!

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