Bovine pestivirus or bovine viral diarrhoea virus (BVDV) and mucosal disease in cattle

Adapted from Western Australia Department of Agriculture  Bovine pestivirus or Bovine Viral Diarrhoea (BVDV) are the same disease – different people call the different things. We will call it BVDV in this article. BVDV is one of the most complicated cattle diseases we deal with. Don’t worry if you need to ask or read articles a few times to understand the disease. We often do as well. BVDV can be a serious threat to beef farm production and profitability. This article, some of which comes from the Western Australian Department of Agriculture, explains the effect of BVDV on different groups of animals. What happens when BVDV occurs? The effect of BVDV depends on whether it occurs in unborn calves, pregnant cows, feedlot or other cattle. Unborn calves Most of the harm done by BVDV is to unborn calves and depends upon timing of infection. Infection of a naïve cow (one notpreviously been exposed to or vaccinated for BVDV) in early pregnancy causes loss of the embryo. Infection of naïve cows in mid-pregnancy can cause abortions, birth defects and live-born calves to be persistently infected with BVDV. These calves spread the disease within and between herds. Most of these calves die within two years of mucosal disease. By the last third of pregnancy, the calf has developed sufficiently to produce immunity. Some of these calves may be aborted, but most are born healthy. Pregnant cows Infection of a naïve cow results in a mild 2–3 week illness that suppresses the cow’s immune system and reduces disease resistance. Most important are the effects on her unborn calf noted above. After recovery...

Fertility Testing Bulls

by Dr Charlie Blackwood In our seasonal calving system, a key factor for production is ensuring cows get in calf as early as possible in the joining period. This means the cows need to be cycling as soon as possible after calving. Nutrition and ensuring heifers are well grown are critical factors. This also means the bulls need to be fertile to ensure the cows get in calf as soon as possible. A full bull breeding examination requires bulls to meet a set of standards for key fertility components. Passing these components increases the probability of the bull being fertile. The components of bull fertility testing are: Scrotal circumference and tone or resilience Physical examination for faults in the head, legs, joints, feet, sheath and penis Semen analysis for motility Morphology (or structure of the individual sperm cells)   A summary of the four components of bull fertility examination follows: Scrotum - Scrotal circumference/size in centimetres where testes shape is within normal range. The minimum values depend on breed and age of the bull. Physical – Within the constraints of a standard examination, there is no evidence of any general physical/structural condition or of a physical condition of the reproductive tract indicating sub-fertility or infertility. This evaluation will identify structurally unsound bulls in legs, feet, sheath and general structure. Semen – Crush-side assessment indicates that the semen is within normal range for motility, colour and percent progressively motile and is suitable for laboratory evaluation. Morphology – Semen examination of percent normal sperm using high power magnification to ensure minimum standards for normal function are achieved. Can we examine and categorize the...

Why Vaccination is Critical

CHRONIC PULPY KIDNEY – Focal symmetrical encephalomalacia In December a client lost 10 out of 300 six month old lambs he had purchased a few months earlier. The farmer had been told the lambs were fully vaccinated, so no vaccination was done. The lambs were growing perfectly until just before Christmas when 2 lambs became staggery, were unable to rise and died in a few days. Luckily the farmer drenched and vaccinated the lambs with 5 in 1. When one more lamb died, we were called and did a post mortem. Lab testing diagnosed a condition called CHRONIC PULPY KIDNEY or Focal symmetrical encephalomalacia (FSE). In total 10 lambs died before the vaccination took effect. FSE is a form of enterotoxaemia caused by Cl perfringens type D in animals with partial immunity or who suffer only partial intoxication. The signs are referrable to chronic neurological damage. The disease is usually sporadic and affects animals of any age although young animals are more likely to be affected. Clinical signs Clinical signs are similar to those of a condition called PEM or polio. They include blindness, aimless wandering, circling and head-pressing. The sheep become laterally recumbent, mostly quietly but with intermittent paddling and head flexion. The course of the disease varies between 3 and 10 days, before death intervenes. Diagnosis The brain develops soft swellings which can be seen grossly but are fully identified under the microscope. Treatment and prevention There is no effective treatment. Prevention is the same as for pulpy kidney. For a A full description of clostridial diseases of sheep and cattle read the article Clostridial Diseases of...

Clostridial Diseases of Sheep and Cattle

Blackleg, pulpy kidney (enterotoxaemia), black disease, tetanus, malignant oedema and botulism are clostridial diseases that cause death in sheep and cattle throughout Australia. Other animals, particularly goats, are also susceptible. The Clostridial Family of Bacteria Clostridial organisms of various types are found in the soil, where they can survive for a very long time. In fact, when conditions are favourable, some organisms can even multiply in the soil. Most clostridial organisms can also occur quite naturally in the gut of healthy animals. They live there causing no trouble, pass in the manure of animals, and consequently, contaminate the soil. When conditions are favourable for the uncontrolled growth of clostridial organisms they produce powerful toxins (poisons). The effects of these toxins are usually fatal. Diagnosis The most important thing to do when sudden deaths of stock occur is to get an accurate diagnosis. This is important to rule out other conditions, such as metabolic diseases, poisonings and anthrax. Animals suspected of dying from anthrax should not be moved or cut up in any way. Many of the clostridial diseases can look like anthrax and so should be approached with caution. If anthrax is suspected, contact your veterinarian immediately. Clostridial diseases are usually fatal. Death occurs rapidly with pulpy kidney, black disease, blackleg and botulism, but takes several days to weeks with tetanus. In severe outbreaks, many animals die suddenly. Occasional deaths may be due to these diseases also. These are often undiagnosed. Treatment Treatment with antitoxins and large doses of antibiotics is expensive and not usually successful. Vaccination is vital to prevent these diseases. Prevention and Control The major factor...

Coccidiosis – Looking after your calves!

  Coccidiosis – Looking after your calves! Coccidiosis has been seen on several farms around the district, renewing our need to ensure calves are protected! There are several ways this can be done, including medicated feeding, pasture management and proper hygiene. The Disease Coccidiosis is caused by a protozoal parasite that invades and multiplies in the cells lining the intestine. It causes severe, often blood-stained diarrhoea, and usually occurs in calves over three weeks of age. Factors that predispose to the development of coccidiosis include those of nutritional, climatic or management stresses, as well as other diseases. It is important to remember that coccidia can survive on pasture from year to year, so prevention is necessary every year! It is commonly associated with overstocked paddocks, or where there is poor pasture management. Calves become infected by licking the coats of infected herd mates or from the ground, walls or other contaminated surfaces. Calves usually contract the resilient and highly infectious coccidia in times of stress, such as when calves are weaned onto pasture. Control The disease is most commonly controlled with the use of a preventative (coccidiostat), such as Rumensin (Monensin), Lasalocid, or Decoquinate. These are usually added to calf pellets or as an additive in milk replacers. Monensin is required at a dose rate of 1mg/kg of body weight (BW) as a preventative, and is usually found in pellets at a dose of 50-100mg/kg of feed. This means that a 50kg calf needs to eat ½ to 1kg of pellets a day, depending on what pellet you are using. The most important note to take is that in...

Acute Bovine Liver Disease

Acute Bovine Liver Disease By Dr Charlie Blackwood Acute Bovine Liver Disease (ABLD) is a relatively recent condition that we are still learning about. It is currently notifiable as the DPI are trying to collate as much information about this condition as possible. With the relatively mild summer and associated growth, and warmth and moisture around, it is possible ABLD could arise on farms this year. What is it? ABLD was previously known as phytotoxic hepatitis, is a disease of beef and dairy cattle. Outbreaks have been recorded in South Australia, SW Victoria, Tasmania and NSW. The actual cause of the condition is unknown, but it is associated with the presence of the native grass Cynosurus echinatus (Rough Dogs Tail). However, it is unknown whether the plant is directly involved or whether it is merely an “indicator” of some other factor. Cases of ABLD are usually associated with the introduction of cattle onto less fertile paddocks (or parts of paddocks) which have dry feed containing Rough Dogs Tail still standing from the previous spring/summer and with green grass growing underneath. It seems together with the correct weather conditions, this creates the right environment for the disease to develop. Signs of ABLD may be observed within hours of introducing cattle to the affected paddock, or may not develop straight away. Signs of the Disease Signs are variable – but as the name suggests are related to liver disease. Signs seen include: Death of cattle - this may occur suddenly or occur take as few days. Often only a few cows are affected. In the worst cases, 30% or more of...