AnimailWelcome!YOUR ANIMAL HEALTH PROFESSIONAL

July

Welcome to the July Animail from Tauranga Vets. The calving season is upon us and many of you will already be hard at work in the paddock and calf sheds caring for your young stock and introducing new cows to the shed for milking. For those with a later calving date, you’ll be tidying up loose ends

on the farm in readiness for a busy few weeks ahead. Wet weather can add to the challenge of managing your stock with some animals struggling more than most. To that end, we outline what do to if Mud Fever strikes and we highlight the hidden dangers of high nitrate levels in your pasture. We also focus on how to handle downer cows and we’ve a helpful reminder about drenching best practices. As always, we’re just a phone call away so if you need help with your animal health on the farm or lifestyle block, don’t hesitate to call.

For more information visit www.bopvets.co.nz | Tauranga 07 578 4044 | Te Puna 07 552 4015 | Katikati 07 549 0215

Recently we’ve dealt with a case of severe parasitism which has highlighted again for us the importance of using combination

drenches on your stock.

The level of infection in a group of R1 calves resulted in the death of some animals while significantly inhibiting the growth of others in the mob.

A post mortem was conducted on one animal and large numbers of worms were found in the intestinal wall lining as well as damage to the abomasal lining. This group of calves had been regularly drenched with Cydectin and faecal samples collected 10-12 days after drenching still indicated significant worms remained.

Poor results after drenching can happen for several reasons such as:

inaccurate or under dosing as there is often a wide weight range within a group affected by parasites

parasite resistance to the active ingredient in the drench.

Young cattle in New Zealand are commonly affected by a worm called Cooperia. An Agrisearch trial demonstrated the importance of using combination drenches to treat Cooperia. Only 5 out of 14 farms in the trial achieved greater than 95% efficacy (baseline for an effective drench) with oral moxidectin and none via injection or pour-on methods.

For successful treatment of Cooperia, this trial supports the current recommendation of using a drenching product which contains Levamisole.

The other main parasite that affects young cattle is Ostertagia. The key difference between the two is that Cooperia live mainly in the lumen of the small intestine, while Ostertagia larvae actually cause damage living in the abomasal wall. Given that these are quite different types

of worms, living in different parts of the body, with different drench sensitivity, a combination product is recommended.

We stock a range of combination products including oral, injectable or pour-on. Sustainable and profitable drenching needs to take into account the best drench type, timing of drenching, and the treatment regime. We also have a set of electronic weigh scales for hire to help increase the accuracy of dosing.

The most expensive drench is the one that doesn’t work! So come and talk to us about the best options for your farm.

It’s Mud Fever season

Tauranga and the Western Bay have had their fair share of rainfall in recent weeks so now is a good time to remind ourselves about the kinds of animal health

problems that coincide with wet conditions.

Livestock exposed to persistent rain or mud can fall victim to what’s commonly referred to as “Muddy Fever”, “Rain Scald”, “Greasy Heal”, “Strawberry Footrot” and “Lumpy Wool”. All these health problems are caused by an actinomycete bacteria called Dermatophilus congolensis. These infections were once thought to be caused by a fungus and to this day many people mistakenly still think that this is the case.

The bacteria causes skin infections in many animals - horses, cattle, sheep, goats, alpacas, dogs, cats and sometimes even humans. The infection is usually characterised by an exudative dermatitis and the formation of scabs. In severe infections, these scabs can affect large areas.

As several of its names suggest, it’s most commonly associated with wet conditions.

Animals that are exposed to persistent wet weather or mud, where their skin becomes saturated with water are at risk. This risk is increased when parasites such as biting flies, ticks and lice cause further damage to the skin and they can also transfer the bacteria from animal to animal, thus allowing the bacteria to get into the skin.

Diagnosis is based on the typical lesions which develop and include symptoms like crusts, loss of hair in tufts, heat and swelling or “juicy”, pus-filled craters on the skin. Close examination of the crusts or skin will ultimately determine the cause – under a microscope long, railway track-looking and sometimes branching filaments of cocci are seen, which is why it was first thought to be a fungus.

Treatment

In mild cases, treatment isn’t usually necessary. The first priority is to get the animals out of damp, wet or muddy conditions to prevent their condition from getting worse. More serious cases can be treated effectively with topical antibacterials. In horses, the best treatment is to

use iodine or hlorhexidine containing shampoos such as Vetadine or Pyohex, wetting the affected areas, gently removing the crusts and allowing the shampoo to contact the skin for 5-10 minutes, before rinsing and drying the area.

More severe cases may require veterinary intervention. Antibiotics can be used if infections do not respond to topical therapy or become too widespread.

Protect yourself

Dermatophilosis can be transmitted to people. Direct contact with an infected animal can lead to infections on the hands, legs or arms. Affected animals should be handled with gloves, and thorough hand washing with an antibacterial soap is recommended after contact with an infected animal.

If you have an animal that you think is being affected by Dermatophilus or you are having difficulty treating ‘Mud Fever’ or ‘Rain Scald’, please contact one of our

veterinarians for further advice.

Parasites inyoung stock

We hope you enjoyed this Tauranga, Te Puna and

Katikati Vets newsletter.

Take a moment to visit the Tauranga Vets Facebook page,

www.facebook.com/taurangavets,and Like what you see.

We love your feedback and are always happy to answer your animal health questions.

Tauranga Vets

www.bopvets.co.nz

Nitrate Poisoning in

Cattle

We’re available to talk to you on the phone too. So don’t hesitate to contact us anytime Tauranga 07 578 4044 | Te Puna 07 552 4015 | Katikati 07 549 0215

The Downer Cow

Have you ever treated a cow for an apparently simple case of milk fever, only to find her still sitting there looking at you several hours later?

Frustrating eh! These are the cows we call “Downer Cows”.

They are officially defined as a cow which has been “down” usually in sternal recumbency (ie sitting up on her brisket) for 12 hours or more but without obvious illness. A downer cow is usually bright and alert but unable to rise.

A cow can be “a down cow” for a whole lot of reasons but becomes a “downer” if she fails to fully respond to treatment for the primary condition.

A seasonal problem

Downer cows usually occur around calving - from a couple of days before calving until about 10 days after. Half of downer cows have calved within the previous 24 hours. Most often the primary cause of the cow being down at this time will be milk fever but it’s important to remember that some other conditions such as acute mastitis or a calving injury

can prevent a cow from getting up, so it’s important to quickly check for other conditions before you start treatment for milk fever.

The downer syndrome happens due to secondary damage to muscle and nerves from the cow being down in the first place. The weight of the cow sitting on the lower leg impairs the blood circulation which leads to a lack of oxygen to the affected muscles and nerves to the extent that those organs lose the ability to work properly.

Prompt investigation and treatment is important to achieve a good outcome with these cows. If you have found a cow down in the morning, treated her for milk fever but she is still down after lunch, give us a call so we can come the same day to assess her and, where possible, treat her.

Diagnosis and treatment

The vet will give her a thorough examination to rule out other conditions such as systemic mastitis, metritis or blood poisoning. We’ll also assess the extent of any muscle or nerve damage. A plan can then be made for the cow’s treatment and nursing and a prediction made as to the likelihood of recovery.

Sometimes a further treatment of calcium, magnesium and dextrose will be enough to get her up and walking. Other times an injection of painkillers will make the difference.

If she still can’t get up, she will require nursing for a few days. This will involve providing good feed and water, clean dry bedding, and rolling her from side to side every few hours. If hip lifters or a sling are available, these can be used to pick her up and hopefully she will then be able to stand unassisted. However if she can’t stand, she should not be left hanging in the lifters or sling as this will do more harm than good. Interestingly, a cow bath or flotation tank is quite effective at getting many of these cows up and about, but unfortunately this option is not available locally.

She should also be milked out twice daily to prevent the onset of mastitis.

A blood sample can be taken and the results used to make a prediction about her chances of recovery. If the results show the cow is unlikely to recover, it will be more humane to euthanase her, and will save you a lot of time, effort and frustration looking after a hopeless case.

Any downer cow that has been down for 5-7 days should be re-assessed. Cows down for longer than this are less likely to recover, but there are lots of stories about cows who stayed down for weeks and then got up and walked away.

Prepare calving/ lambing paddocks – don’t

graze effluent/ high potassium paddocks

Magnesium supplementation 4 – 6 weeks

pre calving

BVD test and vaccinate bulls/heifers

Be prepared for calving time - mastitis

checking and treatments

Electrolytes and metabolics – phone us for

competitive pricing

Are trace elements all adequate?

Induction consults

Clostridial protection – Ewe 5-in-1 or lamb’s

PK anti-Tetanus vaccine

CHECKLIST REMINDERS

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E-injection, Genesis Pour-on and Ivomec Plus.See the entry form in our clinics for details.

Recently our vets have diagnosed a case of nitrate poisoning in young stock. While the sunny Bay of Plenty doesn’t normally suit the occurrence of this disease, recent

warm and overcast conditions have reminded us we’re not immune to occasional incidents in this part of the country.

Factors leading to nitrate poisoning

Generally it’s most commonly seen on new pasture. It would appear that well fertilized, new pasture seems to take up nitrogen from the soil and store it as nitrate in the leaf. Climatic conditions, such as seen in the autumn with cool growing conditions and overcast days, favour the uptake of nitrate.

The poisoning can be due to chronic or acute exposure to nitrate. In chronic exposure, cattle may be grazing pasture which contains modest levels of nitrate but the levels gradually build up in the body to the point where poisoning occurs. This would be seen where cows have been in a paddock for 4 or 5 days and eventually some animals become affected.

In acute poisoning the levels in the pasture are toxic and the animals die due to acute toxicity. Animals in this situation would be affected on the first day. With acute toxicity, it takes about 5 hours for the nitrate levels to build up to toxic levels in the blood.Nitrate binds to the haemoglobin in the blood and prevents it from being able to carry oxygen. The combined nitrate and haemoglobin forms methaemoglobin which has a characteristic brown

colour which makes the blood look like chocolate. This can be quite obvious in the living animal but once an animal has been dead for a while it’s not so noticeable.

Clinical signs

Generally the first signs are dead animals in the paddock. Sometimes large numbers are affected. Other animals will be seen sitting down and attempts to move affected animals will see them staggering and having difficulty breathing.

As oxygen levels in the blood drop, the foetus dies due to anoxia and some of the surviving animals may also abort later on.

Treatment

The treatment for nitrate poisoning is an intense blue dye called Methylene Blue. This is given intravenously to affected animals and the effect is rapid and they quickly return to normal.

Prevention

Because of the risks of nitrate poisoning, new pastures should be tested before grazing. Generally pasture that is less than 1% nitrate is safe to graze. Anything between 1% and 2% is considered toxic. Lab test kits are also available for farmers to use. However, the test has to be followed precisely to give accurate results and must be kept refrigerated to ensure that the kit remains in good condition.  

Pasture that is very high in nitrate may be left before re-testing to see if the levels have dropped. Some pasture that has got too long without the nitrate levels dropping may be made into silage to render it safe for stock.

If you’re worried about nitrate levels affecting your stock, don’t hesitate to give one of our Large Animal vets a call.

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