Vol. XII. Xo. 292. 



THE AGRICULTURAL NEWS. 



219 



VETERINARY NOTES. 



A NEW DISEASE OF HORSES IN PANAMA. 



A recent publication issued by the Panama Canal Zone 

 .Xfedical Association (Vol. IH, \\\Tt 2, 1911) describes 

 ^ disease called .MuVrina, induced by a parasite identified 

 as J'ryjMnosoma hijipicum, nv. sp. 



The disease tirst showed itselt in the f^nn of an 

 epidemic amongst American mules and work horses in 

 Panama. The disease resembled other trypanosoraal 

 diseases such as Xagana, Surrah, ]\Ial de Caderas and Sene- 

 ijinibian horse disease; but it presented a group of symptoms 

 and pathological features which made it likely that it was 

 distinct from these. It is entirely a disease of mules and 

 horses, for cattle are not susceptible. The agent, T. /n/ij/iriuii,, 

 referred to above, possesses morphological and biological 

 characters which ditier from other species of trypanosomes. 

 These specific differences may be seen by referring to the 

 bulletin under consideration. 



The clinical features or symptoms of the di.sease are 

 described in the publication as follows: 'general weakness and 

 droopiness, followed by progressive emaciation, the coat 

 becoming rough and staring. At tirst there are febrile 

 paroxysms, and later an irregular or continued fever, reaching 

 104° or 10G° F , rarely 107° or 108° F. A severe anaemia 

 develops, with pallor or a muddy colijur, and ecchymosis of 

 the nasal and ocular conjunctivie. Toward the end of the 

 disease in some animals a staggering gait was noticed. 

 Extreme emaciation, edema of sheath, lower abdominal 

 walls or legs, were features observed in some animals per- 

 aiitted to die of the disease ' 



The disease is probably transmitted mechanically by 

 -flies through the broken skins of cuts and various wounds. 

 Saddle horses were not infected and there was no evidence 

 that any animals were infected by means of stomoxys (stable 

 Hies) or tabanids (bot Hies), or by ticks or bats. The epidemic, 

 which threatened to destroy several hundred mules and 

 horses, has been controlled by isolating animals that have 

 been found to have been infected. The presence of the 

 disease was detected by means of daily routine temperature 

 records, and the microscopical examination of the blood of all 

 those animals which were found to have a temperature above 

 100° F. All inf«cted animals were killed, whilst suspects 

 were isolated in screened stables. 



INTERPRETATION OF MILK RECORDS. 



The practice of keeping milk records is almost non- 

 existent in the West Indies, but in England, and in all 

 countries where dairying constitutes an important industry, 

 the use of this form of statistic is becoming more and more 

 recognized. 



The value of knowing what weight of milk a cow is 

 yielding lies in several directions: it supplies irrefutable 

 evidence to show the extent to which one animal is better 

 than another; it provides a basis for selection in breeding; 

 and it serves to indicate the influence of changes of food and 

 environment on the animals normal physiological, somatic 

 capacity for giving milk. 



Hitherto breeders have generally relied upon such 

 figures as total yield per calf, yield per calendar year, 

 average per week, etc., but the enormous fluctuations exhib- 

 ited in the same animal show these to be subject to a var- 

 iety of outside influences. 



Quite recently the results of an important investigation 

 tave been published in the Journal of fhe Royal Aijio-nltural 



Societi/ of England, Vol. 7.i, of which the object has been to 

 find a method of obtaining from ordinary records, a single 

 unqualified figure which will accurately describe the milking 

 capacity of any cow. 



The descriptive figure devised in the investigation under 

 consideration is called the 'revised maximum', and consists 

 in the maximum day-yield three times reached or exceeded. 



This figure bears a close relationship to the total yield 

 of a normal lactation, and shows rather less variation than 

 that total. It is outside two of the most active external 

 infiuences, namely length of lactation and time of service, 

 and it is suggested that general environment has a minimum 

 effect on it. Further, a cow can usually be judged withiri 

 a few weeks of calving, .Mnoe normal lactation totals caa 

 be estimited from the 'revised maximum' with considerable 

 accuracy. 



It is not necessary to enter here into the mathematical 

 methods employed in the investigation that brought out 

 this important result It may be noted, however, that the 

 research was only rendered possible, in the first instance, 

 through the existence of many years' reliable records, — which 

 in itself should provide sufficient stimulus for an extension 

 of the practice, even to the West Indies. 



Frieslancl Cattle. — In the more settled portions 

 of South Africa, those who rear live stock appear to be no 

 longer content to derive profits entirely from breeding 

 animals for the production of beef, but look to provide, 

 further, a regular monthly income from milk, or milk 

 products, in some form or another. 



A note on this question has recently appeared ia 

 the Rhodesia Agricidlnral Journal, where attention ia 

 directed to the difficulty of quickly breeding from native 

 stock, milch cows of a sufficiently high standard for 

 the purpose of developing the dairying side of cattle 

 breeding. In 1909 it was decided in a certain quarter, 

 to import Friesland cattle from Cape Colony. A good deal 

 of anxiety existed in view of the susceptibility of these 

 animals to several diseases that are common in Rhodesia, 

 but the health of the animals was successfully maintained 

 during the first year by spraying them, to keep down ticks. 

 Eventually the animals became gradually innocuous to 

 tick-borne diseases, and the experiment is to be regarded ay 

 having proved successful. 



With reference to the above article on a new disease of 

 horses in Panama, a reprint from the Journal of Experi- 

 mental Medicine, Vol. .Wll, No. 5, states that it has nof;^ 

 been possible to cure the disease by means of arsenic as haa 

 been done in the case of surrah disease. The disease ia 

 question, trypanosomiasis, is believed to occupy a position 

 between malaria and syphilis, with regard to the amount of 

 actively acquired immunity derived from infection. l-]x- 

 periments were carried out with a view of showing 

 that immunization of large animals can be effected by means 

 of a weakened strain of the pathogenic trypanosome which 

 causes the disease iTri/panofoma kij/piruiu), that immunized 

 animals completely recover from the infection, aud that they 

 cannot be reinfected by the same strain nor by a virulent 

 strain of the same species. It is believed that a practicable 

 mode of immunization of large animals to forms of trypano- 

 somiasis can be developed. In one experiment a mule whioh 

 had been vaccinated in this way was later reinoculated with 

 a virulent strain of the organisms recently obtained from 

 a fatal case of the di.sease in a Panaraan pony; but there were 

 DO symptoms, rising temperature, baemagglutination, not 

 trypanosomes. 



