COMMON INFECTIOUS HORSE DISEASES

​

TETANUS (LOCK JAW)

This is caused by a bacteria clostridium botulinum.  The bacterial spores are found in the soil and if entering a cut which seals over, then the bacteria multiplies in the anaerobic environment and produces a neurotoxin.

Symptoms can appear with protrusion of the third eyelid and stiff neck extending to increased overall muscle stiffness causing swaying of the animal.  The condition is often fatal as it progresses in an ascending manner eventually causing paralysis of the major systems and organs.

​

EQUINE ENCEPHALOMYELITIS (SLEEPING SICKNESS)

Found across Eastern and Western USA extending down into upper South America.  The disease is carried by mosquitoes and shows signs of progressive depression, high fever, pseudo blindness, nervousness and non co-ordinated muscle action, tremors and ultimately complete paralysis.

​

EQUINE HERPES VIRUS

There are two types of herpes virus EHV-1, EHV-2.  EHV-1 is associated with respiratory diseases (fever, nasal discharge, hard cough), reproductive problems (abortion, stillbirth) and neurological problems (hind limb weakness, difficulty walking, sometimes paralysis).

EHV-2 is generally associated with respiratory illness.  Both conditions can appear or are worsened by stress.

​

ROSS RIVER VIRUS

In Australia and some other countries, this mosquito born disease can affect horses resulting in lameness, extreme lethargy, tenderness in joints (throughout the animal and not only located in the legs) and inability to perform.  It is likened to severe arthritis.

​

WEST NILE VIRUS

Carried by mosquitoes, this infection causes signs of fever, weakness, paralysis of hind limbs, vision impairment, stumbling and poor co-ordination, interference with the swallow reflex response and occasional coma.

​

RABIES

Uncommon in horses, but can be infected through a bite from a raccoon, skunk, fox, dog or bat.

​

STRANGLES

A contagious bacterial respiratory disease with symptoms of thick yellow nasal discharge, fever and swollen abscessed lymph glands under the jaw.  The infection is contagious (worse in younger horses) and is frequently spread through shared drinking water from troughs.

​

POTOMAC HORSE FEVER

Only found in limited areas of the USA and is mainly a spring/summer condition.  Fever, depression, profuse watery diarrhea are main symptoms but can lead onto colic, laminitis, dehydration and possible death.

​

INTERNAL PARASITES FOUND IN HORSES

​

The main part of the lifecycle of these parasites occurs inside the horses stomach or intestine and generally begins with the horse grazing on pasture where the horses have deposited their manure in which the eggs/larvae are contained.  The horse swallows these and they enter the gut areas and depending on the species can migrate to other organs such as the liver or lungs.

​

ROUND WORM (Ascarids)

These can cause coughing, pneumonia, liver damage, diarrhea and colic.  If large numbers occur, then intestinal blockage or rupture can occur.

​

TAPEWORM (Cestodes)

Can lead to colic, retarded growth, nutrient deficiencies and rough hair growth.  A heavy infestation is the general cause of colic.

​

STOMACH WORMS

These are transmitted by horse of marsh flies.  They include Habronema muscae, Habronema microstoma, Draschia megastoma, Trichostrongylus axei.  If the horse licks where the flies have laid eggs on its skin, then the larvae are ingested to the stomach.  These generally cause diarrhea.  If the larvae on the skin get into a cut or open sore, they can cause a granuloma (a raised sore that won't heal).  This can be extremely itchy and the horse can scratch and itch at the area causing severe trauma to the area.

​

LARGE STRONGYLES (Blood worms, red worms)

These begin the cycle of infestation by the horse grazing on or around drinking contaminated water.  This parasite (strongylus vulgaris) matures and lives mainly in the blood vessels of the intestines.  Two other types (strongylus edentates and strongylus equines) migrate into the liver.  These parasites can cause severe or even fatal blood vessel rupture leading to heavy blood loss.  Other symptoms can be less severe including colic, anaemia or weight loss.

​

SMALL STRONGYLES

Cyathostomes (small redworms), different from the large strongyles burrow into the wall of the large colon.  Here they can live for years but if erupting in large numbers cause severe problems of diarrhea, weakness, muscle wasting and colic.

​

LUNG WORMS (Dictyocaulus arnfieldi)

Mainly found in donkeys, but can infect co-pastured horses.  Causes coughing and poor performance and is worse when exercising.

​

THREADWORMS

Strongyloides westerii, are mainly ingested through the mothers milk.  Can also be in the bedding and penetrate through the skin.  Main symptom is diarrhea.  Foals generally become immune to these about three months old.

​

FILARIAL PARASITES (Onchocerca cervicalis, microfilariae)

These live on adults in the nuchal ligament in the neck.  The larvae migrate to the skin and cause severe itching which can be so severe the horse will roll and scratch until the skin is red and hair rubbed off.  Frequently found along the belly, chest, eyelids and withers.

​

HAIR WORMS (Trichostrongylus Axei)

Found in the stomach and if a heavy infestation is present can lead to watery diarrhea.

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​