Page 734 - The Veterinary Care of the Horse

It is often suggested that the horse is suffering from a postviral lethargy syndrome. This may

be the case for some horses, but a significant number have no history of recent bacterial or
VetBooks.ir viral infection. Other possible causes include:
•
chronic exposure to stressful situations such as transport and competitions causing high
levels of corticosteroids to be released into the circulation

• over-exertion in the training period.

TREATMENT

A number of horses will recover with rest, good management and time. Two treatments are
used with reasonable levels of success.

1 Levamisole is an immune stimulant. It is added to the feed for a period of 2 weeks.

2 A good quality aloe vera oral gel can be added to the feed at a high dose for 3–5 weeks.
This preparation which is extracted from aloe plants has been shown to be effective in a
number of cases.

Many horses that have failed to respond to other treatments respond well to the oral aloe vera
medication. The white cell count improves and this coincides with improved performance
and general vitality.

PREVENTION

It is difficult to make recommendations when the condition is not fully understood. However,
it makes sense to:

• take care not to work the horse too early after a bacterial or viral infection

• take it easy for a couple of days following a vaccination
• try to reduce the stress levels of the horse.

THE LYMPHATIC SYSTEM

The lymphatic system is a branching network of lymphatic vessels. Tiny, blind-ending lymph

vessels are found in the tissues. These drain into progressively larger vessels which
eventually empty into the large veins near the heart. Their function is to drain excess fluid

from the tissues. In contrast to the circulation of blood, the movement of the lymph is
assisted by the action of muscles rather than being pumped by the heart. Valves in the vessels
prevent backflow and ensure one-way flow of the lymph.