and observing the peripheral signs which will vary according to which valve or valves are affected. The most common sign is engorged jugular veins. Treatment is a very prolonged course of antibiotics which seldom cure the disease. If the cow improves it is important that she receives full antibiotic cover at her next calving.
Heartwater
This is caused by a rickettsia, Ehrlichia ruminantium, which is spread by Amblyomma spp. ticks. It occurs in tropical Africa, the Caribbean, South and Central America and tropical parts of the USA. The disease is normally acute with a high fever and an increased vascular permeability, which causes hydropericardium and hydrothorax. These signs lead on to fatal neurological signs. Diagnosis is confirmed by the presence of the organism in Diff-Quik stained brain smears. Treatment is with high doses of oxytetracycline. Control is through effective tick control and vaccination.
Lightning strike
This assumes an over-importance in farmers’ minds in the UK as it normally is the only condition which their cattle are insured against. Sudden death in groups of cattle without signs of a struggle after a storm is reasonable evidence of lightning strike, particularly if they are all in contact with a wire fence. Burn marks may be seen on the medial aspects of the legs and haemorrhagic streaks will be seen on careful skinning.
Lyme disease
This condition is caused by the spirochaete Borrelia burgdorferi and is a worldwide zoo-nosis. It is not primarily a disease of cattle but will cause joint infection, which may be an immune-mediated response. Cattle will have swollen joints on their lower limbs and will be stiff on movement. Diagnosis is by PCR. Treatment with oxytetracycline for 3 weeks together with NSAIDs has been suggested.
Mycoplasma wenyonii
This condition is not fully understood and it is thought to be spread by arthropods or needles from mass vaccination procedures (Strugnell and McAuliffe, 2012). The main clinical signs in the UK are hind limb oedema, pyrexia and painful, swollen udders in dairy cows, with reduced fertility in stock bulls. Clinical signs gradually resolve and a full recovery may take 10 days or longer. Diagnosis is from fresh blood smears taken in a clean environment and stained with Giemsa. Treatment with 3 days of tylosin at 5 mg/kg im is said to be more effective than oxytetracycline at 10 mg/kg im.
Circulatory diseases caused by protozoa and their treatment
Anaplasmosis
The main organism causing this disease is Anaplasma marginale. It is tick borne and occurs in the tropics and subtropics. The main signs are pyrexia and anaemia. Diagnosis can be confirmed by thin blood smears stained with Giemsa. Treatment is with oxytetracyclines or imidocarb dipropionate. Prevention is by tick control.
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
