Chronic fatigue syndrome in horses – treatment with acemannan
Lack of appetite, weight loss, dull coat, tiring easily after exercise and poor performance are
all signs of chronic fatigue syndrome in horses. This condition was first described in the UK
in 1992 and shares many similarities with chronic fatigue syndrome in humans; it can be as
equally debilitating as its human counterpart and as difficult and troublesome to treat.
The exact cause of equine chronic fatigue syndrome is not known. It is widely
believed to be associated with viral infection – and hence commonly called post-viral fatigue
syndrome – and there is some scientific support for this. Antibodies to so-called
enteroviruses are found in approximately 80% of affected horses and it has been suggested
that equine herpes viruses may also be responsible in some cases. These viruses appear to
weaken or suppress the immune system in certain horses, resulting in chronic fatigue
While the symptoms of equine chronic fatigue syndrome range in severity, from a
horse being simply ‘off colour’ to severe illness, it is the persistence of these signs over a
long period of time, in some cases over a year, that is characteristic of the condition. In
addition to the typical signs of a poor or variable appetite, weight loss, tiredness and poor
performance, other symptoms include fever, dry faeces, muscle tremors, and a dry or dull hair
coat. Some horses appear drowsy and apathetic, standing with their head and neck lowered,
eyes closed and taking no interest in their environment. Skin and respiratory infections, as
well as conjunctivitis, can also accompany the condition.
Blood samples taken from affected animals typically demonstrate a reduction in the
numbers of white blood cells (leucopaenia), and specifically of one subset of white cells
called lymphocytes. Many cases are also anaemic, with lower than normal values for red
blood cells and haemoglobin concentrations. The symptoms of equine chronic fatigue
syndrome are related to anaemia together with weakening of the immune system as a result of
the viral infection. Some viruses, particularly the herpes viruses, may also cause muscle
inflammation and pain that contribute to the illness.
Diagnosis of equine chronic fatigue syndrome is usually made on the basis of the
clinical signs shown in conjunction with the results of blood tests. Examination of the upper
airways using an endoscope may reveal the presence of secondary bacterial infections and
differentiate the condition from recurrent airway obstruction. The presence of recurrent skin
infections, which respond to antibiotic treatment but simply recur once this has finished, is
also suggestive of suppression of the immune system.
Treatments for equine chronic fatigue syndrome include rest and vitamin and mineral
supplements to help correct the anaemia. The most important goal of therapy is, however, to
support the repair of the immune system and the regeneration of white blood cells and
lymphocytes in particular. Vets in the UK will typically use the medicines levamisole and
gamma-interferon in an attempt to stimulate the immune system and these help in some but
not all cases. Bacterial products (e.g. EqStim and Equimmune) have been shown to
strengthen the immune system in clinical trials and are available in the USA, but there is as
yet no data on their efficacy in equine chronic fatigue syndrome.
Arguably the most promising immunostimulant is the plant extract acemannan. This
is a potent anti-viral agent that also has the ability to enhance the immune system and
particularly the function of lymphocytes. It is extracted from the pulp of the meaty leaves of
Aloe Vera plants and in its injectable form is used for the treatment of certain cancers of dogs
and cats. There are a number of user reports of the use of Aloe Vera products in equine
chronic fatigue syndrome, with the authors finding that oral supplementation with Aloe Vera
Gel resulted in significant improvements in health and blood counts.
‘Vinnie’ was a 12 year-old gelding, competing at Intermediate level eventing, that
suddenly went off his food, developed a nasal discharge and cough, and had a fever. Blood
samples showed a markedly reduced white blood cell count, almost total depletion of
lymphocytes, and low haematocrit which is a measure of the red blood cells and indicator of
anaemia (Table 1). Initial treatment with antibiotics and a bronchodilator improved Vinnie’s
respiratory condition and subsequent endoscopic examination revealed no significant
abnormalities. A second blood sample taken 4 weeks later showed that the white blood cell
and lymphocyte counts were increased and so Vinnie returned to work.
Some 3 months later the owner became concerned that Vinnie was not able to cope
with his competition programme and was tiring easily. He performed badly in the cross
country phases of several one day events, with an unusual number of jumping penalties and
retiring afterwards at one event and then on the course in another. Further blood tests on
28/05/07 revealed a lowering of the white blood cell and lymphocyte counts, although he was
now no longer anaemic. These parameters remained low despite treatment with a dietary
copper supplement, levamisole and inteferon over the ensuing 2 months. Vinnie was then
turned out to grass for 3 months, with no ridden exercise.
Prolonged rest did not improve the blood picture, with the white blood cell count in
particular remaining low, and this did not improve with further rest over the winter months.
In the spring of 2008 the owner Laura Swinnerton and her vet, Dr Tim Watson of the Equine
Veterinary Clinic in Renfrewshire, came across an article on the usefulness of acemannan in
post-viral lethargy syndromes and Vinnie was started on a 6-week treatment with Aloe Vera
Laura soon noticed an improvement in Vinnie’s demeanour and general condition.
Blood samples taken towards the end of the treatment period on 20/06/08 showed a
substantial improvements in white blood cell and lymphocyte counts, which had more than
doubled during the course of treatment and were now well within the normal range, as well as
the haematocrit. This was accompanied by a transformation in his work, with him being
much more responsive, not tiring and making fewer jumping errors. Vinnie returned to
competitive activities soon after and has continued to perform well.
Vinnie’s story is typical of many horses with equine chronic fatigue syndrome and
serves to illustrate the frustration that it can cause owners, particularly of competition horses.
Symptoms can persist for a long period of time – in Vinnie’s instance well over 12 months –
and treatment, including prolonged rest, can be ineffective.
His case also highlights the lack of efficacy of traditional veterinary treatments,
including immunostimulants, but fortunately shows the very positive benefit of acemannan in
the form of Aloe Vera Gel. The 6 week course cost £180 from Karen Lodge, Independent
Distributor of Forever Living Products (please see contact details below) and was backed by
a 60 day money back guarantee that promised a full refund if there was no improvement.
It is testament to the benefits of acemannan that Laura continues to give Vinnie Aloe
Vera at a maintenance dose and that her vet, Dr Tim Watson, has adopted the treatment as his
principle therapy for horses with equine chronic fatigue syndrome.
For more information on Forever Living Products Aloe Vera Gel, and indeed any of their
products, or if you would like to order product please contact Karen Lodge direct on either
01505 872219/07973 930285 or email at firstname.lastname@example.org
1. Aloe Vera plant
2. Vinnie back to health on the cross country course.
Table 1. White blood cell, lymphocyte and haematocrit parameters in Vinnie over the course
of his illness and treatment.
White blood cell Lymphocyte count Haematocrit (%)
count (x109/L) (x109/L)
Normal Range 5.4 – 14.3 1.5 – 7.7 32 - 53
18/01/2007 – onset of 3.7 0.7 29
13/02/2007 – prior to 4.9 1.6 31
return to work
28/05/2007 – 3.6 1.1 32
22/06/2007 – after 4.5 1.1 35
07/11/2007 – after 3.3 1.7 32
being turned out for 3
25/03/2008 – after 3.1 1.2 31
winter off work
20/06/2008 – after 6.8 2.8 38
Aloe Vera Gel