Icterohaemoglobinuria or Red Water in calves has been recognised throughout Australia as a distinct disease entity for many years, but it was not until 1949 that Queensland workers demonstrated that leptospira were the cause of the condition in that State (Sutherland, Simmons and Kenny). This organism has been proved since responsible for the disease in other States and in New Zealand. In New South Wales leptospirosis in calves has been confirmed on properties in the Casino, Tweed-Lismore, Grafton, Port Macquarie, Moss Vale, Gundagai and Deniliquin P.P. Districts during the last two years, and there is little doubt that it was responsible for the many earlier calf mortalities in which icterus and haemoglobinuria were the prominent symptoms.
The disease usually affects calves from 3 weeks to 5 months of age and at times has been responsible for mortalities of 100%. At other times losses have been lighter and animals have recovered. It is quite likely that many mild cases occur and recover, without ever being detected. Leptospirosis also affects adult cattle but symptoms, when observed, are not so severe and most cases recover. However, recovered cases may excrete leptospira in the urine for some time and thus provide a source of infection. Pigs have been shown to harbour leptospira without showing obvious signs of illhealth, and may excrete organisms for many months after initial infection. In view of the close contact of pigs with calves on many dairy farms in this State, the pig also must be regarded as a likely source of infection.
In the experimentally produced case of leptospirosis, which can be followed from the time of infection, there is an incubation period of 4-14 days before the onset of fever. The temperature may rise to 105-107° (F) and usually is followed by the appearance of icterus and haemoglobinuria, the latter persisting for one, two or up to six days. The degree of icterus may vary from a slight yellow tinge to a marked jaundice, while in some cases clinical jaundice may not be observed. The presence of haemoglobin in the urine may not appear until some days after the jaundice, and in some cases the excretion of haemoglobin does not occur at all.
Leptospira are not usually excreted in the urine in great numbers until some days after the disappearance of haemoglobinuria. but in recovered cases the organisms may continue to be excreted in the urine for some weeks or even months.Under field conditions, where it is not passible to follow the course of the disease closely, the onset is usually sudden and death may occur within 24 hours of the first symtoms being observed oy the stockowner. Symptoms include lethargy, disinclination to move, lack of interest in food or water and the animals are easily fatigued. Jaundice and the passage of red water are usually observed by the farmer.
There is usually anaemia, some degree of icterus and the presence of reddish brown urine in the bladder. The liver and spleen are enlarged. The capsule of the kidney often is adherent to the cortex, while petechiae may be present beneath the capsule and on section.
Aureomycin and streptomycin, which destroy the leptospira, have been found superior to penicillin owing to the fact that the latter antibiotic, although controlling the disease, allows the organism to be excreted in the urine for some time after recovery. Sulphamerazine also has been used successfully. Treatment with any of these drugs is most effective when administered during the early stages of the disease, preferably before excretion of haemoglobin commences, but a certain amount of success can be expected by treatment of the more advanced cases. During an outbreak it may be advisable to observe animals closely and regularly so that treatment of cases can be commenced immediately the first symptoms become apparent.
In view of the evidence that contact with pigs may provide an important source of infection, it is most desirable that pigs be housed, or grazed, on areas to which the calves cannot have access. Leptospira can survive for some months in mud or pools which have been contaminated with infected urine, so such areas should be drained or fenced off, or the calves removed to other paddocks. Any calves introduced or born afer an outbreak has occurred should be grazed apart from the infected herd and their environment.
Diagnosis in the laboratory is confirmed by the recovery or demonstration of leptospira or agglutinins by one of the following methods:—
1. Dark ground examination of fresh kidney and a centrifuged urine sample. If the latter cannot be examined immediately it should be preserved by the addition of 0.5% formalin immediately after collection.
2. Cultural examination of fresh liver and kidney.
3. Inoculation of guinea pigs with citrated blood, fresh urine, and with unpreserved liver and kidney.
4. Demonstration of leptospira by histological examination of liver and kidney sections preserved in formal saline.
5. Demonstration of agglutinins in the sera.
As it is not always possible to rely on any one of the above methods to confirm the diagnosis, specimens should include:—
(a) Urine fresh and preserved with formalin, from both affected and recovered cases.
(b) Citrated blood from affected calves.
(c) Liver and kidney sections both fresh and preserved with formalin.
(d) Sera from affected and recovered cases.
1. Sutherland, A.K., Simmons, G.C. and Kenny. G.C. (1949)—Aust. Vet. J., 25 : 197