202 
PARASITIC DISEASE IN HORSES. 
and also the almost absolute certainty of new diseased action 
being induced thereby. 
Such knowledge will enable the practitioner to understand, 
to some extent, the particular organs each variety of entozoa 
locates itself in, and also that certain kinds are singularly 
erratic in their habits. It will likewise assist him in interpret¬ 
ing the symptoms of the disease they produce, and in 
suggesting suitable therapeutics for the expulsion of the 
parasites from the body of the animal. 
Very little is known of the precise causes which render 
the horse susceptible to the attacks of entozoa, or even 
what that condition may be which makes his interior a 
suitable soil—if I may so express it—for the development 
of ova taken into the system from without, or produced from 
existing parasites already within the organism. It will be 
admitted, 1 think, that some animals become infested with 
parasites, while others, under similar circumstances, alto¬ 
gether escape. Assuming this to be the case, we are forced 
to the conclusion that the systems of some horses are in 
a more favorable condition for the propagation and develop- 
ment of these creatures than those of others. 
The particulars of the case in question are contained in 
the following letter. 
Long Clawson, Melton Mowbray, 
February Ind , 1864. 
Sir, —Knowing from the perusal of your excellent articles, recently 
published in the Veterinarian , that you possess an ardent zeal for the 
promotion of veterinary science, I take the liberty to send you, per 
railway, thinking you would like to lay them before the members of the 
Veterinary Medical Association, portions of the crncum and colon, with 
a small piece of the wall of the abdomen, and the anterior mesenteric 
artery, of a yearling colt. All the parts sent, as you will perceive, 
are infested with worms. Within the mucous membrane, both of the 
caecum and colon, the parasites exist in myriads, and in various con¬ 
ditions. The majority are extremely small, while some are encysted, 
having produced small abscesses. They are apparently ascarides. 
In the mesenteric artery you will observe a different kind of worm, 
which has wrought important changes in the structure of that vessel. 
The areolar tissue underneath the parietal peritoneum affords a nidus for 
another kind, which is larger than that either in the blood-vessel or 
within the mucous membrane of the large intestine. These parasites 
undoubtedly occasioned the death of the animal from which the diseased 
parts were taken. Worms are common in young horses in this neighbour¬ 
hood, and are highly destructive to life. They give rise to symptoms which 
are most distinctive, and to various secondary affections, which, generally 
speaking, are not understood, and which the country practitioner seldom 
refers to the true cause. 
Hoping the specimen may be of use, 
I am, &c., 
To Professor Varnell. Robert Littler. 
