In this district over the past number of years there has been a complaint affecting cattle of all ages, types and condition. It has been seen in fat and store bullocks, wet and dry cows, and in young cattle down to calves a few weeks old.
It is suspected of being Ephemeral Fever in a more virulent form than was seen in the outbreak of this complaint in 1937. It is admitted that at the onset there is a marked similarity to Ephemeral Fever, but as the complaint develops and progresses it drifts away in many aspects from the regular symptoms seen in that disease and there is still a doubt in the mind of the writer that the subject complaint is Ephemeral Fever. Work is being carried out at Glenfield Research Station in connection with this complaint. The writer is of the opinion that the complaint or the attack is vector borne, but just whether the same insect is responsible in both cases is yet undetermined. This complaint usually appears in the early summer and prevails throughout until late autumn, and each year the number of cases have increased. The symptoms seen are not regular and the mortality rate on each holding where the complaint occurs varies considerably. In some instances it is 100 per cent. of the affected cases, on other runs it is nil, and from that up to 100 per cent. of the animals affected.
This complaint appears in several forms, or perhaps I should say as it progresses it develops differently according to the age of the affected animal. Invariably at the onset the symptoms seen in all cases are similar. That is, dullness; ears lopped; grinding of teeth; rapid breathing; marked general stiffness and soreness of all limbs; disinclination to walk; general locomotory disability; high temperature; slight discharge of clear fluid from nose; constipation; slight and continuous grunt and evidence of pain (groaning on handling).
As the disease develops in adult cattle it is found that it usually localises itself in one or more joints.
As the disease develops in calves up to three months old it usually ends fatally without a change of the symptoms seen at the onset. In cattle three to 18 months old it usually takes a different course. The symptoms are similar to those of adult cattle at onset, but very rarely does it localise itself in one of the joints. It progresses slowly, the affected animal will cease to feed, becoming very stiff and sore, lays down a lot, but for the first two or three days can get down and up. If the attack is going to end fatally the calf will lose power of its hind quarters, and that part will sway till it almost falls over. In this case the calf will be unable to rise unless lifted, next day it cannot stand if lifted and will lay flat out on the ground. It usually lives for about three days then dies. In calves up to two months old the complaint usually take a more rapid course and frequently proves fatal in two days.
In some cases the attacks are not so serious, the affected calf will get very stiff and sore, it will stand and lay about but, if on its mother or a poddy will take its feed. It will be very sick for perhaps a week then make a very slow recovery taking many weeks to pick up its lost condition; cases in young calves have been seen where the joint does swell; in these cases there is no partial paralysis of the hind quarters. The joint, usually the knee, will swell considerably. It is most painful and the calf will lose condition rapidly; in the few such cases seen not one has ended fatally.
The mortality rate in each case varies. On one place three out of three cases died, in another place not one out of nine died, in another five out of 34 calves were affected and one died and so on.
In the course of investigating this complaint numerous post mortems have been conducted. Almost invariably the same set of lesions have been revealed. It is usually found that the blood is normal in quantity and colour, flesh, fatty tissue normal, rumen, reticulum and omasum normal, the abomasum slightly abnormal, there being slight inflammation of the mucosa; small ulcer-like marks in the duodenal end of the stomach. Also seen in some cases were petechial haemorrhages in this organ. Intestines and associated lymphatic glands appeared to be normal, kidney apparently normal.
The liver and spleen appear to be normal in size and colour, lungs showed little departure from normal, the heart was firm and normal in colour, there was evidence of slight petechial haemorrhages on outside. A small quantity of pleural and pericardial fluid was present.
Involvement of the serous membranes seemed to be characteristic in all cases see, as extensive lesions of peritonitis with fibrinous deposits over rumen, liver and bowels, were encountered in almost every post mortem conducted.