Babesiosis
This disease does occur in the UK but is much more important in other areas of the world, mainly in the tropics and subtropics. It is spread by ticks of various species. The main causative organisms are Babesia bigemina and B. bovis. The disease is characterized by acute fever, anaemia and recumbency. Haemoglobinaemia and haemoglobinuria are only seen in the later stages of the disease. Diagnosis can be confirmed by thin blood smears stained with Giemsa. Treatment is with diminazene aceturate or imidocarb dipropionate. The latter is licensed in the UK as the product Imizol injection (imidocarb 85 mg/ml). Prevention outside the UK is carried out by tick control.
Theileriosis
This tropical or subtropical tick-borne disease follows 10 days after exposure to infected ticks so weekly dipping or spraying with acaricide will normally prevent the disease. The most important type is East Coast fever (ECF) which is found in East and Central Africa. ECF is caused by Theileria parva parva and is spread by Rhipicephalus appendiculatus. ECF has a high morbidity and a high mortality. There is a less virulent strain of the parasite, T. p. bovis. T. p. lawrencei causes a similar disease but can only be spread from buffalos to cattle but not from ox to ox. The main presenting signs for all types of theileriosis are high fever and swollen peripheral lymph nodes. Diagnosis can be confirmed by seeing Koch’s blue bodies in lymph node smears. Treatment with buparvaquone is very effective if given in the early stages of the disease. An immunization using an infection-and-treatment regime is used in some areas of East Africa.
Trypanosomiasis
The majority of trypanosomiasis cases occur in areas where the tsetse fly is found as this is the vector for all Trypanosoma spp. that affect cattle. T. vivax causes peracute disease, pyrexia and rapid death. T. brucei brucei causes an acute disease which, if untreated, will result in death. T. congolense causes a more chronic disease with anaemia and weight loss. Diagnosis is confirmed by thick and thin blood smears stained with Giemsa. Treatment is with diminazene aceturate, homidium bromide and chloride, and isometamidium chloride. The latter also has some prophylactic value but does not treat T. b. brucei.
Diseases of the Urinary System
Post-parturient haemoglobinuria
The aetiology of this rare sporadic condition which is found worldwide is not known. Affected animals often have hypophosphatae-mia and hypocupraemia. It tends to occur in older high-producing dairy cows within 4 weeks of calving. Animals will have haemoglobinuria and anaemia. Treatment is supportive with fluids, injections of phosphorus and copper boluses orally.
Pyelonephritis
This is normally an ascending infection caused by E. coli or Corynebacterium renale in recently calved cows, and found worldwide. The main signs are pyrexia, pain on urinating or palpation of the left kidney, if affected, on rectal examination. Diagnosis can be confirmed by ultrasonography or culture of the urine taken by catheterization of the bladder. Treatment is with high doses of antibiotics, penicillin for C. renale or enrofloxacin for E. coli. A minimum of 3 weeks of treatment is suggested.
Renal amyloidosis
This rare sporadic disease is characterized by deposits of amyloid throughout the organs of the body, but particularly in the kidney. There is proteinuria and chronic wasting with diarrhoea shown if the liver or bowel is affected. Diagnosis is not easy, but urine creatinine and urea nitrogen are elevated. Kidney biopsy is definitive. There is no treatment.
Diseases of the Reproductive System
Abortion and its causes
Akabane
This condition is caused by an Orthobunyavirus (Akabane virus) and is spread by several species of mosquito and biting midge. It occurs in the tropics and subtropics, namely in northern Australia, Japan, Korea and South Africa, and the author has seen it in the Middle East. It causes congenital abnormalities in full-term calves as well as abortion, but other than these signs adults are normally asymptomatic. There is a vaccine available.
Arcanobacterium pyogenes
This bacterium is rarely isolated and is found in late-term abortions. There is no vaccine available.
Bacillus licheniformis
This is a rare cause of abortion and is associated with the feeding of poor-quality forage. The cow is not ill but the bacterium is isolated from the fetus or the placenta. There is no vaccine available.
Bovine herpesvirus 1 (BHV 1)
This virus will cause abortion after 150 days post service. There is venereal spread of a strain of virus which appears to be different from the virus that causes respiratory signs. Animals which have aborted are then immune. There is a vaccine, which is not licensed in the UK, which should be given to heifers before service when at risk from the disease.
Bovine viral diarrhoea virus (BVDV)
BVDV may cause infertility problems related to early embryonic death, but abortion is rare. The virus will cause diarrhoea in adult cows and mucosal disease in calves infected in utero (these calves are PI). Infected cows will test serologically positive but virus negative, unlike the PI calves. There are very effective vaccines available.
Brucellosis
This is caused by the bacterium Brucella abortus. The disease has largely been eradicated in the EU and totally eradicated in the UK, where it is notifiable. It is highly contagious via the products of abortion and is a zoonosis. It will cause late abortion storms in naive cattle. There are two vaccines available, one of which does not interfere with the serology used for eradication programmes. Diagnosis is by bacteriological examination of the fetus, the placenta and milk, or by the detection of antibodies in blood or milk.
Campylobacter fetus subsp. veneralis
This is an obligate bacterial parasite of the reproductive tract and cannot survive outside the host for any appreciable time. Normally it causes early embryonic death. This can be reduced by blanket injections to the cows of streptomycin. Bulls can be cleaned by prepu-tial washing with an oily preparation of streptomycin for 3 days.
Chlamydophila abortus
This bacterium is a common cause of abortion in sheep, but is extremely rare in cattle. However, it is important as it is a zoonosis.
Coxiella burnetii
This bacterium causes Q fever which does occur sporadically in cattle causing late abortions and stillbirths. It is found worldwide (except in New Zealand). Diagnosis is best by histopathology and staining with a modified ZN stain. The organism is spread in milk, placenta, urine and faeces, and is zoonotic. At the time of writing there is no cattle vaccine but there is a vaccine for goats.
Leptospira icterohaemorrhagiae
This organism is very rare but is associated with a serious systemic illness in cattle, which will show clinical jaundice. In some instances, the pyrexia from the systemic disease will cause an abortion. In other instances, the organism will be isolated from the abortion products.
Leptospira