SUSCEPTIBILITY 1 
evidence in support of this assertion. Nevertheless, it 
is fortunately true that, in the great majority of cases, 
one attack confers an active resistance to future infec- 
tion; thus in purchasing dogs it is certainly wiser to 
give preference to those which have attained the age of 
about twelve months, and which in consequence can be 
assumed to have passed the danger zone. 
Age at which Dogs are attacked—Distemper is most 
commonly met with in puppies from six weeks to nine 
months old, and cases have been observed in pups even 
as young as ten to fourteen days, whilst in rare instances 
very old dogs have become infected. 
’ It will thus be noted that the disease is most prevalent 
during the process of dentition. 
Many writers declare that certain breeds of dog have a 
marked natural immunity, and even attempt to tabulate 
them according to their degree of resistance; but my 
view is that no breed is exempt, and none can claim 
ascendancy in this respect over another, from the point 
of view of “species.” If any difference exists, the real 
reason will be found connected rather with the conditions 
of life and environment inseparable from members of the 
supposed stronger breed. For instance, the shepherd’s 
dog is credited with the greatest immunity, followed in 
order by the terrier, hound, spaniel, pointer, pug, and so 
on down the list, until we reach the highly delicate 
pampered pets, such as Pekingese, Pomeranians, King 
Charles, and Japanese spaniels, griffons, etc.; and it 
cannot be denied that the so-called “hardy”, breeds 
withstand infection and endure its ravages with much 
greater certainty than the delicate breeds, otherwise 
there could be no such distinctions of health drawn 
between the various breeds; but put the sheep dog and 
his like under the unnatural conditions endured by the 
average pet dog, and he will probably be found to be as 
