Bracken fern poisoning is a world wide condition and affects multiple systems of the body. It affects a wide range of domestic animals,and mostly occurs when there is insufficient feed supply. This forces animals to graze for bracken fern. Ptaquisolides are known toxic agent from the bracken fern ,It affects DNA bases leading to oncogenes. Affects Bone marrow leading to immunosuppression , hemorrhages and anemia.Early diagnose is important to prevent further damages.

1. shareefngunguni@gmail.com
C L A S S W O R K , U N P U B L I S H E D
Bracken fern poisoning
Authored By:
LUANAR,2018
Shareef Ngunguni,BVM

2. Page 2
Bracken fern poisoning
Introduction
Bracken fern, or bracken, (Pteridium
aqulinum var esculentum) is a native
perennial fern found in open forest,
or on cleared land where it can form
extensive colonies and be a
troublesome weed that is difficult to
eradicate. During the periods of
reduced food availability, domestic
animals (herbivores and pigs) eat
bracken easily and willingly,
especially its tender young parts
(Gupta, 2012). The effects of bracken
ingestion are diverse, depending on
the animal species and the ingested
dose(s).
Epidemiology
Bracken fern is worldwide distributed
and high risk of bracken poisoning
occurs in countries such as Australia,
New Zealand, Japan, and the United
Kingdom, where bracken is more
prevalent and utilized for human food
or animal feed (Gupta, 2012). The
plant is most favorable in tropical
countries. Bracken fern poisoning is
most common when there is
insufficient supply of high quality
pasture and affect young stocks
around 8-18 months in terms of
cattle. In Malawi blackern fern is
distributed throughout the country
and So far, bracken fern has
increased its net coverage over the
last 30 years on the Nyika plateau
from 1986 to 2016
(Kanzunguze,2018)
Effects on animals/Pathophysiology
The major toxin causing bracken fern
poisoning is the sesquiterpene
glucoside, ptaquiloside (Gupta,
2012). Ptaquilosides binds to base
sequences of DNA resulting in
mutated codons associated with
known oncogenes leading to cancers
and other associated conditions.
Clinical signs
Sub-acute form occurs when the
animal is being exposed to bracken
fern for at least 10days .The
condition causes a wide range of
syndrome in livestock including the
following.
· Interferes with thiaminase, an
enzyme which breaks into
thiamine (vitamin
B1),prymidine and thiazole
(Tourchi-Roudsari,
2014).Thiamine (Vitamin B1)
plays a role in myelination of
peripheral nerves and
Thiamine deficiency leads to
brain damage. This occurs in
monogastrics which have
eaten bracken over several
weeks such as horses and
pigs. Affected animals become
unaware of their surroundings,

3. Page 3
Bracken fern poisoning
can be seen wandering
aimlessly, have an
uncoordinated or staggering
gait, and will eventually lie
down and experience
convulsions.
· neoplasia of gastrointestinal
tract including jaw and liver is
reported in sheep ,bone
marrow, urinary bladder
occurs in mostly in cattle
exposed to bracken fern for
several months.
· Long term consumption of
bracken in sheep leads to non-
fatal diseases such as
progressive retinal
degeneration/ bright
blindness.
Ptaquiloside suppresses bone
marrow causing acute hemorrhagic
syndrome and has carcinogenic
activities in ruminants (Aiello and
Moses, 2016). The bone marrow is a
source of both red blood and white
blood cells. The animal is more
susceptible to infection due reduced
number of white blood cells. Common
clinical signs associated to
lymphopenia include fever, diarrhea,
panting respiration, abdominal pain
and death.
Associated clinical signs for reduced
number of erythrocytes and platelets
include the following
· [1]Bleeding from any external
orifices eg. Nose, anus, vulva,
and mouth. Pale gums,
eyeballs and other surface
membranes [2] Pinpoint
haemorrhages in the skin,
gums, and vaginal surfaces [3]
Blood in the urine [4] Death.
The more chronic form of disease is a
cancer of the bladder wall. In cattle
the condition is called enzootic
hematuria and occurs when cattle
consumes 1-2 kg of bracken for 10-
15 months (Aiello and Moses, 2016).
The clinical signs related to this,
typically being:
· [1]Blood clots in the urine [2]
Red water [3] Thickened
bladder wall [4] Loss of
condition. [5]Death usually
follows but it is a lingering
process in contrast to the
more sudden death which
occurs in the acute form.
Treatment
Effective treatment requires early
diagnosis of the condition (Tourchi-
Roudsari, 2014). Initial treatment is
to discontinue exposure of the
animals to bracken fern or remove
the source of fern and this will lead to

4. Page 4
Bracken fern poisoning
full recovery.
Administration of thiamine in
thiamine deficient horses. Thiamine
is administered at 5mg/kg every 3hr
on day 1 intravenously and then
intramuscularly for several days
(Aiello and Moses, 2016). Thiamine
treatment should also include
animals similarly exposed but not yet
showing clinical disease, because
signs can develop days or weeks after
removal from the source of bracken.
In cattle blood or even platelet
transfusions is effective but require
large volumes (2–4 L blood). Though
untested, aplastic anemia can be
treated with granulocyte-macrophage
colony-stimulating factor (used to
treat aplastic anemia in people)
(Aiello and Moses, 2016).
Secondary infections treated with
antibiotics. Most of the treatments of
the condition become unsuccessful
when diagnosis is done when clinical
manifestations are so severe.
Prevention
Elimination of Bracken fern from
fields through cultivation, slashing or
use of registered herbicides such as
asulam or glyphosate (Aiello and
Moses, 2016) is the surest way of
controlling the fern from fields.
Care should be taken not to allow
hungry, young cattle access to
bracken that has recently been
sprayed, slashed, burnt or cultivated.
A good alternative feed source such
as silage, hay, or cereals must be
provided.
Improvement of the management of
pasture to increase production of
alternative forage in time forage
scarcity like in late summer. Since
animals are forced to eat bracken
when other forages are exhausted.
Conclusion
Bracken fern is worldwide distributed
and available in Malawi. Its toxicity is
due major toxin called ptaquiloside. It
affects a high percentage of animals
and many body systems. The
condition is not documented in
Malawi due to lack of veterinary
toxicologists but cases are still there
in the field.
References
i. Aiello. E.S and Moses.A.M
(2016).The merk Veterinary
Manual. 11th Edition.Merk and
Co,Inc. Kenilworth.
ii. Gupta,C.R.(2012).Veterinary
Toxicology:Basic and Clinical
Principles.2nd Edition.Elsevier
Inc.New York.
iii. Kanzunguze, A. (2018).
Mapping and Remote

5. Page 5
Bracken fern poisoning
Detection of Bracken Fern
Invasion on the Nyika Plateau.
Nyika Vwaza Trust Research
Study Report 2017/18. The
Nyika Vwaza Trust, United
Kingdom.
iv. T o u r c h i - R o u d s a r i , M .
(2014).Multiple effects of
bracken fern under in vivo and
in vitro conditions. Asian
Pacific Journal of Cancer
Prevention, (15),7505-10