Spring Diseases To Watch Out For In Cattle
Why does disease occur in Spring?
During Spring there are many changes occurring, both in animals and the environment. In the last trimester of pregnancy, the energy requirements of the foetus (calf) from the mother drastically increase. The weather is also starting to shift, and with it the grass. All these changes have an effect on our soon-to-be mums, and things can easily go pear shaped without proper preparedness.
Milk Fever:
Milk fever, or hypocalcaemia (low calcium in the blood), occurs normally just after birth, when the cow starts producing a large amount of milk. Milk being milk, contains a lot of calcium, which is drawn from the cow’s blood. Calcium levels can be low to begin with, or the demand may exceed the supply, leading to low calcium levels. Calcium is important for many reasons, but in this case, calcium helps transmit nerve impulses and sustain muscle contraction.
Milk fever normally occurs on dairy farms where the cows are producing lots of milk but can occur on lifestyle blocks.
More milk = Increased calcium demand = Less calcium in the blood = MILK FEVER
Cows may at first appear excitable with noticeable muscle tremors or may be off feed and walking like they are drunk (we call this ataxia). This can progress to recumbency (what we call a ‘down cow’) and depression. Often cows that are low in calcium are also low in magnesium, phosphate and energy. These deficits are all treated at the same time.
Treatment is achieved by supplying the cow with calcium! This can be done via several routes:
In the vein: this supplies calcium almost instantly into the bloodstream. This may only last 6 – 12 hours.
Under the skin: absorption of calcium from here takes longer, but also lasts longer.
Orally: absorption can take up to 24 hours, hence the need for more immediate treatment as well.
Your vet may give calcium via one or more routes depending on the severity and presentation of your cow. Anti-inflammatories are also indicated if the cow has been down. Prevention can be achieved but is normally not needed on lifestyle blocks.
Grass Staggers:
Scientifically known as hypomagnesaemia (low magnesium in the blood) this is a condition that also occurs around the time after calving. It often occurs in conjunction with milk fever and treatment for both is often given at the same time.
Magnesium is at its lowest in the late winter/early springtime, which is coincidentally also the time when our cows are going through changes prior to birth which lead them to ingest less feed. Milk production also requires magnesium, which complicates things further. Magnesium is required for many reasons in the body, but importantly for nerve conduction and muscle function. Essentially, without normal magnesium levels all the muscles start to cramp.
Low pasture Magnesium + Increased Magnesium demand for milk + Decreased appetite around calving = Grass Staggers
We call hypomagnesaemia ‘grass staggers’ as low levels result in spasmic incoordination of the limbs, which results in cows staggering around. Cows can also become recumbent or froth excessively at the mouth and can be abnormally aggressive towards us, so please be safe if you think this may be affecting your cow.
Treatment is similar to the treatment for milk fever; supplementing magnesium either in the vein, under the skin, orally or a combination of these three. Daily intake of magnesium is important, so providing salt blocks or access to good quality pasture is also important. It just so happens that Magnesium is important for Calcium absorption from the gut, so daily intake is doubly important!
Ketosis:
This is when increasing energy requirement surpasses the energy intake, which leads to ketone production.
Energy intake < Energy demand = Low Energy + High Ketones = Ketosis
The clinical signs are again, often vague:
Off feed, duller than usual and not wanting to move about.
Subtle neurological signs such as: aggression, excessive licking, excessive salivation, muscle tremors or a staggering gait.
In severe or longer lasting cases, cows may experience some degree of liver damage. To create ketones for energy when glucose is low, the fat must be processed through the liver. If there is a huge difference between the requirements and the supply of energy, the liver can be overwhelmed by the amount of fat it has to process into ketones.
Treatment comprises of replacing the substances the cow is low in:
Energy: either in the vein or orally (Ketol, Keto-aid).
Electrolyte treatment: this may be warranted depending on your vets assessment.
Anti-inflammatories: especially if your cow has been down.
Prevention can be achieved by feeding high quality pasture or supplemented/concentrate feed to maintain your animals energy intakes to meet their requirements.
Difficulties During Birth:
This is common in grazing animals and can be due to many reasons (including those already discussed above). Mispositioning of the foetus in the uterus can result in difficulties during labour which may require human intervention. Labour is split into three stages:
Stage one: dilation of the cervix
Often you will not notice this stage as it can go on for a couple days before birthing starts. The uterus will start to contract, and the cervix will start to dilate. You may notice a small amount of clear vaginal discharge, or that your cow is a little ‘off.’
Stage two: delivery of the calf
The official start of this is when the placental membrane (water bag) appears at the vulva. The calf should be born within 2 – 3 hours of this time. The majority of heifers (first time calvers) will give birth within one hour of this and cows within 25 minutes.
If your cow has been having difficulty giving birth for over an hour it is time to ring your vet or if you feel confident, having a feel yourself.
Stage three: delivery of the placenta
The placenta should normally be passed by 12hours post calving. Passing can be aided by gentle pressure. If it does not pass it may be a retained membrane. In this case it may warrant antibiotics and anti-inflammatories. Speak to your vet for advice.