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Ask the Vet Column: Watch out for severe ketosis

By Dayna Locitzer, DVM

Dr. Dayna Locitzer, DVM

Severe ketosis is one of those diseases that, if you haven’t seen it very often, you might be confused at what you are seeing. Was my cow bitten by something rabid? Did it get some bad feed and now has circling disease? Why is my cow looking like she’s going to attack me? She has a salt block but she is licking the walls like crazy… What’s going on? Why is she walking funny? All of these are questions I have gotten before diagnosing a cow with severe ketosis. Cows with severe ketosis can act extremely neurologic. They are often licking surfaces, walking erratically, can show aggressive behaviors, and can even be down and thrashing around. While it is certainly important to consider diseases like rabies and listeria, severe ketosis is a less common manifestation of a very common dairy cow disease: ketosis. I wanted to bring this disease to your attention because I have seen it pop up on my calls to pasture-based dairies, all having similar predisposing factors and presentation: cows with a Body Condition Score >3.75 and had a long dry period.

But first, what is ketosis exactly? It is when an animal’s energy requirements are not met by their energy intake, and they begin to utilize fat stores to make up for it. These fat stores metabolize into ketones, which are then used to make glucose (the metabolism’s fuel). This glucose is used in a lactating cow’s everyday bodily functions like milk production. A little bit of this process happens for all cows at calving. When this mismatch of energy ins and outs is very significant, large amounts of ketones end up circulating in the system and they are toxic to the animal’s bloodstream. Cows are most at risk of ketosis during their first month of lactation because of the high demand for energy as they come into their milk and progress towards peak lactation. In mild cases of ketosis you might see a drop in milk production or they might be acting sluggish. You also might not see any outward clinical signs, but ketosis still has an effect on their body in the form of inhibiting their immune system and negatively affecting fertility. Mild cases can progress to severe cases where you will see a dramatic drop in milk production, decreased rumen function, and the neurologic signs I listed earlier. Cows that have had ketosis have an increased likelihood of developing a displaced abomasum, mastitis, metritis, and often end up on the cull list. Their early culling might not directly be because of ketosis, but many end up being poor doers because of it.

It is my observation that ketosis isn’t as big of a problem on small organic pasture-based dairies as it is on conventional operations. I think this is because of a few reasons: 1) Though organic cows produce a lot of milk, they typically are not pressured to produce the high amounts that cows are asked to produce on larger conventional dairies. 2) They have access to digestible fibers via their high forage diet that keep their rumen full and functioning well, thereby supplying their metabolism with enough energy. But just because it hasn’t been a problem on your farm doesn’t mean it won’t be in the future.

It is helpful to know what cows are predisposed to ketosis to prevent it from happening. Cows that are at risk of ketosis are ones that have poor nutrition leading up to calving, poor nutrition after calving, cows that have varying degrees of milk fever, very high producing cows, and cows that are overweight at calving. Cows that are overweight at calving are at particular risk of severe ketosis, specifically if they are greater than 3.75 body condition score (BCS) at calving. This is because when cows with high BCS are in negative energy balance, i.e. when their energy intake doesn’t match up to their energy needs, they have more fat to burn. The more fat they are mobilizing for their energy needs, the more toxins from ketones are in their bloodstream, leading to a case of severe neurologic ketosis. This can also lead to “fatty liver disease” because the fat that is being mobilized and metabolized has to pass through the liver. That fat clogs up the pathways in the liver, causing the liver to not function due to back up. A cow with severe ketosis and fatty liver disease becomes hard to treat because a malfunctioning liver makes it a lot harder to recover from disease. So, when you do not provide an overweight cow with proper nutrition before, at, and after calving, she will be at high risk for developing severe ketosis.

There are lots of factors in cows being overweight, some that we can control and some we can’t. One important factor that we can control is getting cows pregnant on time, ideally in less than 120 days in milk (DIM). As you extend their open period past this point, you are risking either them having a longer lactation or a longer dry period, both of which can lead to overweight cows. As a lactation progresses and milk production decreases, they are apt to use the energy in their lactating diet to make body fat. A long dry period has a similar effect. While not all cows with long lactations or long dry periods will have an increased BCS, it does increase the risk of becoming overweight and therefore increased risk of severe ketosis.

What happens if you do have an overweight cow calving, and what happens if you do have a cow with severe ketosis? First, if you have an overweight cow about to calve, you can make sure she is getting a high energy diet with lots of good quality forages and that she has feed in front of her at all times. Make sure she gets a calcium bolus at calving, then again 12 hours later. Check her for ketosis starting at 3 DIM and continue to check her until she is 14 DIM, which is the highest risk time.

If an animal develops severe ketosis, this is urgent and she needs to be treated as soon as possible or the disease can progress. Severe ketosis, an animal that shows up with “Large” ketones on the urine test or a BHB blood test of >3.0 mmol/L, should be treated with intravenous dextrose and injectable B vitamins. You should then follow up with an oral treatment of 300cc of propylene glycol for 3-5 days. Propylene glycol was approved for organic use in 2019. If the cow is neurologic or down, I would suggest consulting with your veterinarian on care.

I wrote about breeding cows on time as an important factor. I know that time to first insemination is a controversial topic, but what I would like to stress is that body condition score is an important element around the decision to breed a cow past that 120 day mark. Severe ketosis is mostly avoidable but if this comes up on your farms hopefully this gives you tools to manage it and prevent it from happening again.