Internal parasitism
A wet but mild winter and spring allows large pasture parasite larval populations to survive and challenge young cattle in the late spring and early summer. Calves should be drenched at weaning with an effective oral double or triple combination anthelmintic. Regular drenching with a similar product may be required to prevent clinical parasitism.
Calves younger than 8 weeks of age (or less than 120 kg body weight) are at risk of abamectin toxicity. Drenching calves at this age is unlikely to be necessary; but if you must, it is best to avoid products containing abamectin, such as Converge, Genesis and Matrix. Always follow label and dose rate recommendations.
Yersiniosis
Yersiniosis, a common cause of enteritis in young cattle, is usually brought on by stress such as weaning, transportation or inclement weather. Affected calves show general malaise, listlessness, weight loss and diarrhoea, often containing blood.
Coccidiosis
Coccidia are protozoan parasites causing diarrhoea (often containing blood), and ill-thrift in calves up to 12 months. Straining and a ‘pot-bellied' appearance may be features of coccidiosis. Most cattle develop no clinical signs and mount a strong immune response. Like yersiniosis, coccidiosis is often precipitated by stress. Avoid overstocking young animals in warm, moist conditions. Use pre-weaner and weaner feeds that contain a suitable anti-coccidial drug.
Pneumonia
Pneumonia is caused by a complex of viruses, bacteria and mycoplasma. A change in environmental conditions can trigger pneumonia. Calves may develop signs 7-14 days after a stressful episode, including a dry cough, lethargy, ill-thriftiness and death. Viral pneumonia is often confused with lungworm.
Bovine Virus Diarrhoea (BVD)
In calves between 6-12 months of age which are ill-thrifty, with/or without diarrhoea, and have diseases similar to viral pneumonia, coccidiosis, parasitism or yersiniosis, BVD could be the underlying cause. BVD suppresses the immune system and reduces the calf's ability to fight off challenges from concurrent diseases. In these situations, the probability of a persistently infected (PI) BVD calf running with the mob is high. PI animals excrete huge numbers of BVD virus and provide a continual source of infection. Identify PI animals with blood tests and eliminate the challenge. A BVD vaccine is available.
Clostridial disease
Two vaccinations of a 5-in-1 vaccine four weeks apart at weaning protects calves against the group of bacterial diseases which cause blood poisoning, blackleg and tetanus. 5-in-1 can be used with leptospirosis vaccinations.
Polioencephalomalacia (PEM)
PEM is an induced-vitamin B1 (thiamine) deficiency which is most often triggered by a sudden change in diet. Blindness, incoordination, ‘star-gazing' and ‘dog sitting' are characteristic signs, although in some situations signs can be fairly non-specific. PEM is often confused with ryegrass staggers which occurs mainly in the late summer/autumn period. PEM responds to Vitamin B1, if diagnosis and treatment is early.
If you have any questions regarding this newsletter article, please do not hesitate to contact your vet at Totally Vets.
