MEGRIMS. 341 



collar, they run tlio chance of cerebral congestion from impeded 

 venous circulation ; while, as corroborative of the truth of what 

 has been stated respecting the action of the collar, there is the 

 certainty that animals which have been subject to attacks of 

 megrims when working in the ordinary collar, have enjoyed 

 perfect immunity from such seizures when worked with a strap 

 or band across the breast. This is a fact recognised not in 

 this country only, but wherever horses are employed for draught. 



With respect to those cases where symptoms of cerebral 

 disturbance similar to those attendant on megrims are met 

 with in animals not driven in harness, there need be little 

 hesitation in attributing such to lesions of certain structures 

 of the nervous centre contained within the cranium, which 

 will be noticed immediately. 



c. Anatomical Character's. — As cases of cerebral congestion 

 do not often from this obstruction of the circulation terminate 

 fatally, so we seldom have an opportunity of observing the 

 altered state of the cranial contents. When such have been 

 examined, the indications of the hypenemic state seem 

 generally distributed throughout the entire extent of the 

 cerebral structures. The venous sinuses and vessels of the 

 pia mater are loaded, giving the latter a dark or opaque 

 appearance, while the grey matter of the brain, on being cut 

 with a knife, exhibits over the cut sm^face a greater number 

 and larger size of blood-spots than usually appear, and is as a 

 whole somewhat redder than natural. When the congested 

 state has been one of repeated occurrence, the vessels are en- 

 larged and tortuous. 



Symptoms. — The symptoms indicative of this congestive 

 action and brain-pressure are invariably sudden in their 

 appearance ; there is no premonitory warning ; the animal 

 slackens its pace or suddenly stops ; there is a shaking of the 

 head as if some object had dropped into the ear, or the motion 

 is upwards and downwards ; less frequently the head is turned 

 to the side. The vessels of the face and throat are distended, 

 the eyes stare, the nostrils become dilated, the breathing 

 rapid or stertorous ; the fore-legs are occasionally placed widely 

 apart as if for support; the cervical and facial muscles exhibit 

 a rapid twitching action, while the skin is damp from perspira- 

 tion. Occasionally the attack proceeds no further, relief being 



