Hypokalemia in cattle

Potassium (K) is an essential nutrient in animal nutrition as it plays a crucial part in metabolism. Among other things, it is involved in the function of nerves and muscles, the regulation of the acid-base balance in the body, in maintaining the water balance, and the regulation of the heartbeat. Besides calcium and phosphorus, it is the third most common mineral in the cow’s body, making up 5% of the total mineral content of the body [1]. A deficiency of potassium can cause impaired growth, muscular weakness, and decreased feed intake [2]. In this article, we will explore the symptoms, causes, treatment, and prevention of hypokalemia in dairy cows.

What is hypokalemia in cattle?

Hypokalemia occurs when blood potassium levels in the cow are low. When the serum potassium concentration is between 2.5 and 3.5 mmol/L we talk about moderate hypokalemia, when it is less than 2.5 mmol/L the hypokalemia is severe [3,4]. Potassium doesn’t get stored in the cow’s body, which is why they need their daily amount of potassium from the forage. Normally, hypokalemia in cows is rare because cows' rations usually contain sufficient potassium [5]. Lactating dairy cows may even eat more than ten times their daily potassium requirement. To cope with this excess potassium, cattle have a well-developed renal excretory system [6]. However, hypokalemia is a condition that can have serious consequences if left untreated. Severe cases can still lead to the death of the animal.

What causes hypokalemia in cattle?

A study by the University of Wisconsin-Madison shows that the cases of hypokalemia tended to be concentrated in the first 45 days of lactation [7] while another study mentioned 60 days [8]. In general younger cows seem to be more at risk than older cows [3]. Hypokalemia can be cause by multiple factors:

Inadequate dietary intake: as mentioned before, dairy cows have an excellent system to get excessive potassium out of the body. However, when the intake of potassium stops it takes this system a while to adapt and lower the excretion of potassium. During this time the body keeps excreting large amounts of potassium, thus potentially causing a deficiency. This is why anorectic cows often have moderate hypokalemia [7,8]. Adult cows with a prolonged inappetence (+2 days) have a higher risk of developing hypokalemia [6]. This means that sick cows often develop hypokalemia.

Medications: hypokalemia in dairy cows usually develops as a secondary disease, after other conditions such as ketosis, inappetence, and diarrhea. It is hypothesized that severe hypokalemia can be caused by multiple factors around the treatment of ketosis [8].  Potassium excretion in the kidneys can be increased by the use of some corticosteroids with mineralocorticoid effect. A study on ten cows with hypokalemia showed that all cows had undergone treatment against ketosis with isoflupredone acetate. Multiple dosing decreases plasma concentration of potassium values by 70 to 80% [7,8]. The administration of glucose can also cause a hypokalemic state and some diuretic drug like furosemide, used after a urinary obstruction, have a likewise effect. Lastly, multiple treatments of dextrose and insulin are also considered a risk factor [6].

Excessive potassium loss: Cattle can lose potassium through urine, feces, or sweat. If they are losing more potassium than they are taking in, they may develop hypokalemia. Researchers at the University of Florida discovered a link between heat stress and potassium loss, with cows that stayed in the shade losing five times less potassium than the group of cows that had no shade. Heat-stressed cows also ate less during the daytime, thus also reducing the potassium intake [9].

Symptoms of hypokalemia?

The first sign of hypokalemia is often a reduced feed intake. Other symptoms are also rarely attributed to hypokalemia alone. This is why hypokalemia should always be considered in the diagnosis of weak and recumbent cows. Symptoms include the following [1,6,8,10,11]:

• Recumbency and downer cow syndrome
• Muscular weakness
• Abnormal neck posture (S-shaped neck)
• Stiffness
• Nervous disorders
• Tachycardia (faster heart rate)
• Abnormal electrocardiograms
• Decreased milk production
• Anorexia
• Little to no feces
• Mimicking colic (abdominal pain)
• Poor heat tolerance

Treatment and prevention

Treatment of hypokalemia is preferably done through an oral administration of potassium chloride [7,8]. Since hypokalemia is often a secondary disease it is crucial to note the importance of identifying the primary disease and the following nursing care of it.

Prevention should happen for animals at risk, like cows that aren’t eating well due to calving, illness or surgery, cows with recurrent ketosis and cows receiving more than one injection of corticosteroids with mineralocorticoid effect.  Just like the treatment an oral potassium supplement is the preferred method [6].

Resco’s potassium bolus

Resco developed a fast-release potassium bolus to reduce the risk of hypokalemia in cattle. Two Kalitop boluses (in one application) contain 70 grams of potassium from potassium chloride (KCl). Read all about the potassium bolus on the product page.

Sources

1. Potassium in Animal Nutrition. (1997). Better Crops, 82(3).
2. Tizioto, P. C. et.al. (2014). Calcium and potassium content in beef: Influences on tenderness and associations with molecular markers in Nellore cattle. Meat Science, 96(1), 436–440. 
3. Hypokalemia in Adult Cattle - Metabolic Disorders - MSD Veterinary Manual, n.d.)
4. Hypokaliémie de La Vache Laitière : Réévaluer La Kaliémie 12 Heures Après Le Traitement, n.d.
5. Johns, I.C. et.al. (2004). Hypokalaemia as a cause of recumbency in an adult dairy cow, Australian Veterinary Journal, vol. 82, no. 7, pp. 413-416. 
6. Sattler, N., & Fecteau, G. (2014). Hypokalemia Syndrome in Cattle. Veterinary Clinics of North America-food Animal Practice, 30(2), 351–357. 
7. Peek, S. F., Divers, T. J., Guard, C., Rath, A. P., & Rebhun, W. C. (2000). Hypokalemia, muscle weakness, and recumbency in dairy cattle. Veterinary Therapeutics, 1(4), 235–244.
8. Sielman, E. S., Sweeney, R. W., Whitlock, R. H., & Reams, R. Y. (1997). Hypokalemia syndrome in dairy cows: 10 cases (1992-1996). Javma-journal of The American Veterinary Medical Association, 210(2), 240–243.
9. Mallonee, P. G., Beede, D., Collier, R. J., & Wilcox, C. M. (1985). Production and Physiological Responses of Dairy Cows to Varying Dietary Potassium During Heat Stress. Journal of Dairy Science, 68(6), 1479–1487. 
10. Dennis, R., & Hemken, R. (1978). Potassium Requirements of Dairy Cows in Early and Midlaction. Journal of Dairy Science.
11. Make Sure Cows Get Enough Early Lactation Potassium - Progressive Dairy, n.d.