Ketosis
Ketosis, also known as acetonaemia or ketonaemia is a multifactorial disorder that commonly occurs in dairy cows and buffaloes immediately after calving or in early lactation. The disease is characterized by partial anorexia and depression.
Aetiology: Ketosis occurs due to negative energy balance associated with intense adipose mobilization and a high glucose demand. High yielding dairy cows and buffaloes are more likely to suffer, particularly in the early stage of lactation and immediately after parturition. Peak milk production usually occurs at 4-6 week post- partum, whereas the highest dry matter intake does not occur until 8-10 weeks post- parturition. As such, high yielder may experience a metabolic shortage of gluconeogenic precursors and negative energy balance. This precipitates low glucose and insulin level in blood. Low insulin: glucagons ratio induces mobilization of long chain fatty acids from adipose tissues and promotes ketogenesis in liver. The resultant clinico- pathological changes include high concentration of non-esterified fatty acids (NEFA) and ketone bodies viz acetone, aceto acetic acid and â-hydrobutyrate. Factors that decrease energy supply to animals or stimulate energy supply via fat or that increase demand for glucose enhance ketone body production.
Clinical findings: In dairy cows and buffaloes, ketosis can occur in two clinical forms, viz wasting and nervous. The wasting form is more commonly seen and is characterized by decrease in appetite, and milk yield. The animal is often lethargic and abdomen appears empty. The body weight is rapidly reduced and skin elasticity is lost due to disappearance of subcutaneous fat giving a ‘woody appearance’ to the affected animals. The ‘hang dog’ appearance and disinclination to move and eat indicate abdominal pain. A characteristic ‘acetone’ smell is detectable on the breath and often in milk. Few cases of ‘wasting-form’ may show nervous signs including transient bouts of staggering and partial blindness. Signs in ‘nervous form’ may develop suddenly, which include walking in circle, straddling or crossing of legs, head pushing into the stanchion, apparent blindness, aimless movements and wandering. Depraved appetite, vigorous licking and chewing of the inanimate objects are also seen. There may be hyperesthesia, incoordination and moderate tremor and tetany.
Many cows and buffaloes, which are in negative energy balance during early pregnancy suffer from ‘sub clinical ketosis’, which is characterized by ketonuria and sharp fall in milk yield. Such cases can be identified on repeated urine examination at 5-12 days post-partum.
Diagnosis: The diagnosis of ketosis is established on the basis of case history indicating presence of risk factors, and the biochemical tests to detect the presence of hypoglycaemia, and ketone bodies in blood, milk and urine. In many countries commercial kits for ‘cow-side test’ are available to detect ketone bodies in urine or milk. The majority of these tests are based on detection of acetoacetate or acetone. However, precaution should be taken in using these tests within 48 hours of parturition, since false positive reaction can occur during this period. Ketone body concentration in urine is affected not only by ketone level in blood, but also by the amount of urine excreted. Milk ketone body test is less variable and easier to perform. A ‘milk st rip test’ to detect presence of â-hydroxybutyrate (BHBA) is recently commercialized. The sensitivity and specificity of this test are reported to be 73.96% and 69-96%, respectively.
Treatment and Prevention: Ketosis can be effectively treated by re-establishing normoglycaemia and reducing ketone body production. Administration of 500 ml of 50% glucose intravenously is a common treatment, which provides rapid recovery.Care should be taken to avoid perivascular leakage of the glucose solution as it may cause severe swelling and irritation. Glucocorticoids such as dexamethasone or iso- flupredone acetate at 5-20 mg intramuscularly provide more sustained response. Propylene glycol administered orally at dose rate of 225 gm twice daily for 2 days followed by 110 gm for 2 days gives good results, especially in less severe cases. Use of insulin (200-300 IU) intramuscularly and vitamin B12 is also recommended for treatment of ketosis.
Adequate supply of nutrition to the cows and buffaloes during dry and lactating period is the easiest way to reduce occurrence of ketosis. Feeding of poor quality roughages, wet ensilage and mouldy or dusty hay should be avoided. Oral drench of propylene glycol in early lactation at 350-1000 ml doses daily for 10 days can prevent ketosis. Propylene glycol can also be added in feed.