Julie Nuttall, Author at Oakhill Vets

Wild plants poisonous to livestock

During the grazing months it’s important to look out for cases of plant toxicity. Many poisonous plants are bitter and unpalatable while they are growing and will not be eaten by livestock under normal circumstances. However, if grazing is scarce, such as after a period of dry weather, or when pastures are overstocked it can be more likely. Here are a few of the most common wild toxic plants to look out for.

Ragwort

Ragwort poisoning is seen less commonly, as pasture management usually prevents this plant colonising grazing land. Poisoning can occur from ingestion of the live plant or from conserved forages containing Ragwort. Clinical signs of ragwort poisoning include depression, chronic weight loss, diarrhoea, jaundice and accumulation of fluid under the jaw and brisket caused by liver disease. Sheep are much less susceptible to ragwort than cattle. There is no effective treatment once the liver damage has occurred.

Bracken

Bracken poisoning often occurs when alternative forage is in short supply and animals have little else to eat, additionally some animals develop a taste for the young shoots in the spring. Bracken poisoning requires long-term exposure, over weeks to years. The outcome of ingestion is related to the time period and the quantity ingested. Haematuria (blood in the urine) primarily affects cattle (less commonly sheep) and is often accompanied by anaemia. The toxins cause bone marrow suppression and depletion of white blood cells resulting in immunosuppression. Affected cattle may be weak, exhibit rapid weight loss, high temperature (40°C+), pale mucous membranes, spontaneous bleeding or prolonged bleeding from minor wounds, and blood clots in the faeces. Affected sheep may be blind.

Lower doses of bracken fern ingested over several years are more likely to be carcinogenic and may result in bladder tumours. Poisonings are prevented by not allowing access to bracken, particularly in spring when the young more palatable fronds are emerging. Alternatively, ensure animals have adequate nutrition at all times, so they are not forced to eat bracken as an alternative.

Oak (Acorn)

Acorns contain tannins which cause serious, often fatal, kidney damage. Mass ingestion of acorns may occur following stormy weather. Rumen microbes break down the tannins, producing gallic acid, which causes damage to kidney cells. Animals may show abdominal pain and bloat due to ruminal stasis. They are anorexic, depressed and often recumbent. Constipation may be followed by foetid tarry diarrhoea. Death may occur within hours to several days depending on the number of acorns eaten. It is prudent to fence off oak trees on grazing pastures.

Hemlock water-dropwart

Cattle are particularly at risk of hemlock poisoning after ditches have been cleared out, exposing the most toxic part of the plant, the roots (“dead man’s fingers”). Animals show signs of salivation, dilated pupils, difficulty breathing, collapse and spasmodic convulsions. The majority of affected cattle die.

Bulk milk result round-up

A few weeks ago we collected bulk milk samples from all our dairy farms and screened for the presence of antibodies to IBR, BVD, leptospirosis, liver fluke and Salmonella, depending on their vaccination status. Here’s a summary of the results:

Salmonella dublin

Of the 93 farms tested; 25 herds were positive for S. Dublin antibody and 68 herds were negative.
This signifies that 27% of the unvaccinated herds we tested had been exposed to S. Dublin!

Leptospirosis

45 herds were unvaccinated for leptospirosis and bulk milk screening revealed 29 tested positive and 16 tested negative.
That means that in our sample, 64% of unvaccinated herds had been exposed to leptospirosis.
Within the positive herds: 2% had low levels of antibodies, 49% had medium levels and 49% had high levels of antibodies.

BVD

Of the 44 herds that were unvaccinated against BVD, 37 farms tested positive for BVD antibodies and 7 were negative.
This means that of the unvaccinated farms tested, 84% had been exposed to BVD or had cattle that may have unknown vaccination status.

IBR

Of the 110 dairy herds sampled, 28 do not vaccinate against IBR and were tested for antibody status. Of those 28 farms, half tested positive for IBR antibodies and half tested negative.
Therefore 50% of the unvaccinated herds that we tested had been exposed to IBR.

Fluke

39 herds opted to screen for liver fluke antibodies.
10 herds screened (25%) were negative, 20 herds (52%) had light infestation, 8 herds (21%) had moderate infestation and 1 herd (2%) had heavy infestation.

Thanks to all farms who took part in this project.

Management of the ‘down cow’

The main reasons for a down cow generally are toxic, metabolic, or traumatic. The longer the cow is down, the worse the prognosis as damage to the leg muscles and nerves begins to occur.

Once the cause of the recumbency has been identified and treatment has been planned, the cow can be moved onto soft, clean bedding – Deep straw, sand (20cm minimum), or ideally out to grass if the weather allows. Have good quality feed and clean fresh water available at all times in a position the cow can easily access. Consider using non-steroidal anti-inflammatories

A hip hoist can be a useful tool to lift down cows to prevent them from suffering further injury. Ideally use a hip hoist along with a strap under the chest of the cow to take some of the weight. The hip hoist should be firmly attached around the tuber coxae (indicated in the diagram). Lift the cow slowly as vertically as possible with a loader until in a normal weight-bearing position. DO NOT lift the cow up in the air. Allow the cow to stand with the hoist on, if she won’t weight bear then lower her down. Don’t remove the hoist unless confident she is weight-bearing and won’t stagger over.

All Red Tractor assured farms must now have a written plan in place for the management of down cows. Speak to your vet about making sure yours is upto date.

Img src: BCVA

Managing Milkers At Turnout

Spring grass is attractive as a low cost feed for dairy cows. But how do we manage high yielding herds that wish to graze?

The first question is what cows are suitable for grazing? Dry cows (both far-off and close-up) and early lactation cows are often much easier to manage on a housed diet. Mid and late lactation cows are often the best candidates for grazing – safely back in calf and past peak milk production.

Spring grass has a high crude protein content and often drives excessive body condition loss in early lactation cows. This can have a negative knock-on effect on future health & fertility and increase the likelihood of these cows being culled.

Buffer feeding around turnout is essential – this will naturally happen as cows will be housed at night after milking but to drive intakes, introducing the buffer TMR before milking can be very beneficial.

In wet conditions, bring cows back in after 3 – 4 hours at grass. This protects the grassland and cows will generally have eaten 80 – 90% of their grass allowance at this stage.

Remember to check what the cows are telling you? Monitor rumen fill and dung consistency, look out for cud balls and check milk fats and proteins to ensure cows are happy and productive!

Thinking about breeding your mare?

Pre-Breeding Testing

Taking your mare to stud? Depending on which stud you are going to, you may be asked to test for a variety of diseases.

The most common disease is contagious equine metritis (CEM). This is a bacterial uterine infection caused by T. equigenitalis, K. pneumoniae or P. aeruginosa. Testing involves takes a swab – either clitoral or endometrial (if the mare is in season) – which is then cultured (grown) for at least 7 days, or tested by PCR which gives a result in 1-2 days. The PCR option is slightly more expensive.

Next is EVA or Equine Viral Arteritis. This disease can cause a variety of signs including fever, lethargy, and swelling of eyes, limbs, scrotum and mammary glands. In rare cases it can be fatal. It is spread by both the respiratory (droplets in the air) and venereal (mating) routes. If stallions are infected, they can become chronically infected for years, spreading it to many mares via infected semen. Testing is performed by blood sampling.

Then, there is also Equine Infectious Anaemia (EIA). Horses with EIA are often extremely sick, as the disease damages their red blood cells causing an anaemia. It is spread by the transfer of infected blood, colostrum and semen. Again, this is checked for via a blood sample.

CEM, EVA and EIA are all notifiable disease. The last reported case of CEM in the UK was in February 2022, while the last reported EVA was 2019 and EIA was 2012.

Finally, it is worth mentioning strangles. Whilst this isn’t necessarily related to breeding outbreaks can occur when horses from different sources meet at stud farms. Therefore, some studs require testing, in the form of a blood test, prior to arrival at stud.

As different studs have different test requirements, we recommend that you check your stud’s requirements prior to your veterinary appointment for testing.

Twins

Twins are a problem in horses. This is because only in exceptional cases can a mare give birth to two healthy foals. Should a twin pregnancy continue, sadly most mares will lose both pregnancies mid-late gestation due to lack of space and nutrition for both foetuses.

We can minimise the risk of this by ultrasound scanning mares after covering/insemination. We would usually scan mares between 14-20 days to look for twins. At this stage it is easier to identify them and manage them. If detected, we will try to abort one of the embryos then recheck a week later to see if the remaining embryo is still healthy.

Artificial Insemination Options

Fresh semen – This is used within 3 hours of being collected. It is the most successful option, as the semen will live for up to 3 days in the mare, meaning the timing of insemination is less critical. However, it is limited to local stallions reducing the options available.

Chilled semen – This needs to be inseminated within 48hrs. It is usually collected and then posted overnight to the mare in a special container. This limits it to stallions within the UK and Europe.

Frozen Semen – After collection, the semen is frozen in liquid nitrogen at -196°C. It can be stored for years after collection, and hence can be shipped around the world. It also means the stallion does not need to be at stud when you’re breeding. However, fertility rates are lower, and the semen only survives in the mare for 6hrs so the timing of insemination with ovulation is crucial.

Along with different semen options, there are some considerations as to its place of origin.

UK semen – With UK semen, there tends to be less postage delays and no issues with regards to customs. If semen is required urgently, then it can be collected in person.

Foreign semen – With semen originating abroad, there is a higher risk of delivery delays meaning missed cycles. Since Brexit there has been an increase in problems with health paperwork and customs delays. However, semen from a much larger range of stallions is available giving you more choice regarding how to produce your perfect foal!

Sweet Itch

Sweet itch is a common disease of horses in summer causing them to rub their mane, tail and body. It is caused by a hypersensitive reaction to the saliva of the female Culicoides midge. Affected patients can suffer from frenzied itching of the mane, tail, head, poll and abdominal areas. This results in loss of hair/fur, skin thickening and in severe cases, open wounds from self-trauma.

How can you manage it?

There are three main approaches to approaching/managing sweet itch: midge avoidance, soothing creams/shampoos and medications.

Avoidance is better than cure so the most effective method is midge avoidance. This includes:

Stabling mid-afternoon to mid-morning, as midges are most active dawn to dusk.
Using fans in the stables to help reduce midges.
Choosing open (windy) fields, avoiding woodlands and areas of standing/stagnant water.
Keep muck heaps away from grazing.
Using full fly rugs, to provide a physical barrier.
Fly/midge repellents, especially those with contain permethrin or cypermethrin which should last a couple of days- we can provide small bottles of these on request, which will dilute to 500ml of repellent.

In mild clinical cases, topical management through the use of soothing creams/shampoos on affected areas is generally the first port of call. While these products do not treat the problem, they improve the comfort of the affected patient. Oatmeal containing products are gentle and soothing for irritated skin. Benzyl benzoate can also help, but be very careful if the skin is broken as it can irritate these areas. There are also a number of prescription-only topical medications which can be prescribed by your vet.

Medical treatments

Antihistamines may/may not be of assistance in such patients. Use is off licence in horses and the response is very variable with some horses showing improvement in clinical signs whereas in others, no response is noted.

In severely affected patients, oral or injectable medications, the most efficacious being steroids, are required to control the allergy.

Finally, allergy testing is an expanding area, which can be coupled with desensitisation therapy. If you are interested in going down these routes, it is worth discussing it with one of our vets for more information as it is a complex topic. On a similar note, some people use a ringworm vaccine to try and reduce the signs of sweet itch. Some owners report a good response; however, there is limited evidence it is effective, especially as ring worm and sweet itch are two very different disease processes. Again, if you are interested in this, it is worth talking to our vets.

Ultimately the best but most difficult management method is controlling a horse’s exposure to midges; however, as per the above, there are other options available to help manage the disease when this isn’t enough.

Itchy Skin

As warmer weather approaches, a lot of animals may start becoming itchy. If this itching becomes excessive, skin infections and irritation can make your pet miserable. There are many possible reasons for the itch: parasites, bacterial infections and allergic skin disease are some of the main causes, and in some cases all of these may be seen together.

Dogs and cats with allergic skin disease can be itchy all over, or the irritation can be localised to the feet, face, ears and stomach – or even just one of these areas.

Allergic skin disease (or atopy) is particularly common at this time of year. The three most common types of allergies are:

Flea allergic dermatitis (FAD):

Some pets develop an allergic reaction to the fleas’ saliva. An itchy dog and its environment must be thoroughly treated for fleas before FAD can be ruled out.

Environmental allergens:

This is an allergic reaction to a substance (allergens) in the environment. These allergens can be seasonal (grass and tree pollens) or non-seasonal (house dust mites). The causative agents can be determined by either a blood test or intra dermal skin testing. This condition is more common in dogs compared to cats. It usually affects dogs initially between the ages of 1-3 years and the condition can last a lifetime. There appears to be an inherited predisposition with certain breeds such as Westies, Labradors, Shar Peis and Staffordshire Bull Terriers, although it can be seen in any breed.

Food allergy or intolerance:

This is the least common cause of allergic skin disease. Pets can be allergic to particular components of the food. A strict food trial (please speak to your vet for the appropriate diet recommendation) for a period of 4-6 weeks is needed followed by re-introduction of food components to confirm a diagnosis.

The approach to investigating an itchy dog can be intensive and time consuming, but depending on the cause of your pet’s itchiness we have a wide variety of treatments available to control their symptoms and keep them comfortable and happy. Please ring to book a consultation at the surgery to discuss both investigation and treatment with one of our vets.

Anaesthesia with ‘Womble’

Under a general anaesthetic, concsciousness is lost preventing pain and stress to the horse before, during and after major surgery. Horses that are to undergo surgery under general anaesthesia are admitted to the clinic the day before their procedure. They will be thoroughly assessed to detect any potential risks. This involves examining the heart, lungs and checking for signs of infection. Based on the assessment the anaesthetic plan will be modified to suit the horse. The horse will be weighed to ensure accurate drug dosages are given.

Horses are sedated to reduce stress while its neck is clipped and a catheter placed to allow safe access to the horses vein throughout the operation. If the horse has shoes then these will also be removed to minimise injury to itself, with the feet scrubbed to prevent contamination of the theatre and surgical site.

The horse will then be sedated further and carefully walked into our specially designed induction/ recovery box which has a padded floor and walls to help prevent injury. A padded head collar is applied to prevent injury to the head and face on induction.

Two vets induce anaestheisa via an injection and ensure the horse is guided down as safely as possible. Once anaesthetised (unconscious) a breathing tube is placed via the horses mouth into the airway so that anaesthetic gases and oxygen can be inhaled throughout the surgery to keep the horse anaesthetised and safely immbolised.

The horse is then transported into theatre by a mechanical hoist, where it is placed on a padded mattress to help support the horse’s weight and muscles during the surgery. Monitoring equipment is also applied to the horse to allow the anaesthetist to observe the horse’s depth of anaesthesia and monitor its breathing, eye reflexes, blood pressure, heart rate and rhythm.

Once the surgery is complete, the horse is carefully transported back into the recovery box which is kept warm and quiet to allow for a safe and easy recovery. The horse will usually be on its own in the box at this point as movements can be unpredictable, making it dangerous for people to be in with it. However, the anaesthetist closely monitors the horse during recovery via CCTV allowing them to intervene if required. The surgery is only considered complete when the horse is safely standing up.

Jess Watson BSc BVSc Cert AVP MRCVS
Veterinary Surgeon

NEW purpose-built farm building for 2023

We are thrilled to announce that we have plans for a new purpose-built farm building. Our practice has expanded significantly in all sectors since we started off in the original building many, many years ago, and our farm department in particular was in need of more space.

The building will include a surgical suite, laboratory and large meeting room as well as a farm-only reception area and dispensary. We look forward to welcoming you into our new home!

Do you have a lungworm prevention strategy?

To prevent lungworm causing problems in your herd it is vital to plan ahead. Relying on anthelmintics can be risky as it is very difficult to predict exactly when outbreaks will occur as they are dictated by the weather.

The clinical signs of lungworm include:

Coughing
Increased breathing rate
Fever
Milk drop
Death

Lungworm can persist from year to year in two ways:

Overwintered larvae may survive on pasture from autumn until late spring in sufficient numbers to initiate infection.
10-20% of previously grazed animals carry some larvae over winter → these larvae recommence development in spring and contaminate the pasture.

The larvae levels on pasture gradually build up and outbreaks are usually seen from July onwards; often after a period of warm, wet weather.

In comparison to gut worms, lungworms produce many more eggs, which develop into the infective stage within the faecal pat in 1 week, regardless of the weather (gut worm eggs only develop if the weather conditions are favourable → this can take weeks). This allows the number of infective larvae on pasture to build up rapidly.

Lungworm larvae are expelled in the faeces. The larvae leave the faecal pat to the surrounding grass. The larvae can move further afield using the Pilobolus fungus, which “explodes” making the larvae airborne. Watch the fungus explosion here: https://www.youtube.com/watch?v=TrKJAojmB1Y

Dry, hot summers reduce lungworm contamination on pasture but this creates a future risk as repeated exposure to the parasite is needed to maintain immunity.

Affected dairy herds can lose on average 4kg milk/cow/day (estimated £140 per cow), with an average increase in calving interval of 30 days. Body condition loss is seen and heavy infections may result in death. Suckler herds will see a drop in conception rates, an increased barren rate and a loss of body condition. Reduced milk yields will have a knock-on effect on daily liveweight gain in the calves.

We are increasingly seeing lungworm outbreaks in older cows. Possible reasons for this include:

Reliance on long-acting wormers in calves.
Wet and warm summer weather.
Early turn outs (previously grazed stock contaminate pastures with larvae that have overwintered in their lungs)
High stocking density (more cows = more shedding of lungworm → numbers build up on pasture quickly).

Vaccination provides the best form of protection which will last for the duration of the grazing season. Alternatively, targeted treatment of calves with anthelmintics at times of peak risk can work, but it can be difficult to accurately predict the perfect window for treatment. The use of long-acting worming products is not advised as this does not allow calves to develop their own immunity, is detrimental to dung beetle populations, and increases the risk of anthelmintic resistance.

Cattle need to encounter lungworm at every grazing season to boost their immunity. To ensure immunity without the detrimental effects of this disease, cattle should either receive a booster of lungworm vaccine or be treated with an appropriate anthelmintic at times of peak risk. Purchased heifers and adult cows may succumb to disease if they have not encountered lungworm or been vaccinated previously. If grazed these should be given a complete course of vaccination prior to turn out.

Lungworm outbreaks are detrimental for welfare and costly:

Parasitic pneumonia can result in severe lung damage
Reduced growth rates
Prolonged disease
Death
Reduced milk yield in adult cows