64 THE DISEASES OP HORSES, 



lubricates the intestines, and should be treated as diarrhoea, to which 

 article I refer readers. 



N. 



Nasal Gleet.— See Gleet, also Catarrh. 



Nasal Polypus.— See Polypus. 



Navicular Disease. — The existence of this disease is difficult to deter, 

 mine by the amateur ; even the skilled veterinary surgeon at times finds it 

 difficult to distinguish between that and other causes of lameness arising 

 from affections of that most beautiful but complex piece of mechanism the 

 foot of the horse. The navicular bone, which is placed behind and between 

 the lower pastern and coffin bone, and rests on the perforans tendon, 

 although of small size, is one of the most important parts of the horse's 

 structure ; it comes into play in every motion, and its free action is 

 assisted by a synovial sac, which, placed between the bone and tendon, 

 acts the part of lubricator, and renders motion free and easy. The cause 

 of navicular disease is from sudden pressure by a stone, or some such 

 uneven surface on which the horse may tread, and which first injuring the 

 frog and the tendon referred to bruises the bone ; the frog and tendon, 

 each flexible, soon recover, but the injury to the bone remains permanent. 

 Navicular is a disease most often seen in high class horses and free goers. 

 It makes its appearance suddenly and apparently at the time without 

 cause, and its treatment by an amateur is still more difficult than its 

 diagnosis, and it is much the best plan in cases of lameness, where the 

 cause is not self-evident, to at once take the advice of the best veterinary 

 surgeon at command. If prompt measures are adopted there is a chance 

 of the disease being cured, and, at all events, by a severing of the nerve, 

 which the learned call neurotomy, the poor horse will be saved from incon- 

 ceivable suffering, a result which humane owners of horses will always 

 consider. The acute pain arising from disease of the navicular bone May- 

 hew brings home to the conception of all by comparing it to " twenty 

 toothaches compressed into one agony," and to relieve, or, still better, to 

 prevent such misery, should be a first consideration with, as it is a first 

 duty of, every horse owner. As a preventative of navicular disease, a 

 leather sole is recommended, especially for horses used on hard and 

 macadamised roads. 



Needle Worms.— See Worms. 



Nephritis.— See Kidneys, Inflammation of. 



Nerving", or Neurotomy, is the operation of dividing the nerves ; it ia 

 practised in painful affections of the feet, such as navicular disease ; but 

 it can only be trusted to those skilled in the use of the knife and who have 

 a thorough knowledge of the anatomy of the parts. 



Nettle Rash.— Horses are subject to nettle rash, which consists of 

 diffused swellings in the skin, raised to the thickness of half a crown, and 



