Experimental rickets / by Edward Mellanby.

  • Edward Mellanby
Date:
1921
Catalogue details

Licence: In copyright

Credit: Experimental rickets / by Edward Mellanby. Source: Wellcome Collection.

    8/128 (page 8)
    disease, so that each method has its advantages. Absence of or deficiency in calcium salts may be the outcome of many pathological conditions in addition to rickets, such as osteomalacia, pseudorachitic osteoporosis, scurvy, &c., and, although the pathological anatomy of these diseases is still obscure, there is sufficient knowledge accumulated about rickets to place the histological method of examination in a position of supremacy. The following methods have been used for identifying the rachitic condition : (1) External appearance. (2) Radiographic examination of the bones during life. (3) Histological appearance of the bones. (4) Calcium content of the shafts of the bones. (a) External Appearance. The appearance of rickets in a dog (Fig. 2) is comparable to that of a rachitic child (Fig. 1). The swollen epiphyseal ends of the bones are unmistakable, more particularly at the growing ends of the radius and ulna. This swelling can be well seen in Fig. 2, which is a photo¬ graph of a retriever with rickets. The costochondral junctions also enlarge and, if the dog has a smooth coat, its rickety rosary can often be easily seen. In this work, however, but little reliance has been placed on the swelling of the costochondral junctions, for it has been found to be so variable from animal to animal. A large quickly growing puppy nearly always has more prominent junctions in this position even in a normal state. In other cases, the swelling may be more developed on the inside of the chest, and can only be appreciated after death, although the animal is really rachitic. In very bad cases the costochondral junctions may be drawn in, giving the chest a very deformed appearance. Again, the abdomen is usually prominent in rachitic dogs, and a sulcus corresponding with the well-known Harrison’s sulcus of a child is sometimes seen. As in children, the animal often becomes more lethargic and listless as the rachitic changes develop. The intense interest of the normal healthy puppy in all its surroundings disappears to a large extent, and there is great diminution in its small movements. Often the animal loses its desire to bark, and in this respect resembles a 4 good ’ child with rickets. The muscles are flabby and are unable to contract to allow the animal to run quickly. Long before the bone changes are sufficiently severe to be an impediment the animal may be incapable of running at any speed. Sometimes the effort to run is lamentable, although the appearance of the puppy would not lead any one to suspect this disability. The power to run has often been used by me to test the relative development of the disease in various members of an experimental series, and, although the method is crude, it is sometimes possible to state with reasonable accuracy how the experiment is proceeding. The ligaments of rachitic puppies often become slack and this exaggerates greatly the appearance of bending of the legs. Occa¬ sionally this happens a week or two after the beginning of the experi¬ ment, before any rickets can have developed, and, at that time, such