Garden plants poisonous to livestock

Livestock may eat toxic plant species when they are dried in forages such as hay. So even if you think your livestock can’t access garden plants it’s still important to be aware of which ones are poisonous. Here are a few of the most common toxic garden plants.

Yew

Yew is commonly found in church yards and even small amounts are fatal. It contains highly toxic alkaloids which affect the heart, causing an irregular heartbeat and rapid death. Yew clippings must be disposed of appropriately and good fencing should prevent cattle from entering church yards and gardens.

Rhododendron

Rhododendrons contain a poison (Grayanotoxin) that slows the heart rate and lowers blood pressure. Affected livestock are weak, often recumbent, bloated and may vomit, which is unusual for ruminants. Goats in particular my exhibit dramatic projectile vomiting with rhododendron poisoning. Animals show signs of abdominal pain such as groaning and teeth-grinding. Death may be rapid. As a prevention, ensure stock have access to adequate silage or hay at these times to reduce the likelihood of livestock browsing. Pastures bordering woodland should be inspected for rhododendron and fenced accordingly. Ensure clippings are disposed of appropriately.

Pieris

Ornamental garden shrub. Most commonly nibbled over a garden fence or ingested when hungry animals break into a garden. This plant contains the same toxin as the Rhododendron (Grayanotoxin) and produces similar gastro-intestinal signs and is often fatal.

Laurel

Laurel contains cyanide, one of the most rapidly acting toxins affecting cattle. Cyanide prevents haemoglobin in red blood cells from releasing oxygen, effectively starving the tissues of oxygen. Affected animals initially show excitement, increased breathing and heart rate, and increased salivation. The mucous membranes are bright red, eventually turning blue. Muscle spasm, coma and death follow. Laurel should not be planted where animals can reach.

Grass Sickness in horses

Grass Sickness is a disease of horses, ponies and donkeys in which there is damage to parts of the nervous system which control involuntary functions, producing the main symptom of gut paralysis.

Also known as Equine Grass Sickness (EGS) the cause is unknown but the nature of the damage to the nervous system suggests that a type of toxin is involved – potentially botulism neurotoxin acquired from soil.

The toxin may also affect nerves supplying other body systems resulting in other signs of EGS such as droopy eyelids, inability to swallow & muscle tremors to name but a few.

Three forms of the disease have been reported: the acute, subacute and chronic forms. The form a patient succumbs to depends on the extent of nerve damage.

Horses affected by the acute form of the disease present showing signs of colic often indistinguishable from other forms of colic meaning that it may be suspected that the patient has a twisted gut or other form of surgical colic.

As a result, such patients often undergo colic surgery and the diagnosis of EGS is often made presumptively on the surgery table. This form of the disease is 100% fatal.

In horses with subacute or chronic EGS, the time course of the disease is more gradual and these patients may present with a high heart rate, mild episodes of colic, a tucked up appearance, an inability to swallow, drooling saliva, droopy eyelids, muscle tremors and patchy sweating. This form of the disease is also fatal.

Horses with the chronic EGS may survive but require intensive management to maintain hydration and nutritional requirements. The likelihood of survival depends on the extent of nerve damage.

The only way to definitively diagnose EGS is to examine an intestinal biopsy. Surgery is required to obtain a biopsy. Therefore, horses are frequently diagnosed based on the presence of compatible clinical signs.

Vets often perform an eye drop test known as a phenylephrine test. When these drops are applied to one of the patient’s eyes the droopy eyelid appearance improves. Other conditions may also cause droopy eyelids so this test is by no means perfect.

Horses at risk of succumbing to EGS include any horse at grass but the condition is most commonly seen in young animals aged between 2 & 7 years.

Cases have been reported throughout the year but occur most frequently in late spring/early summer. Overweight horses are also at increased risk. Other reported risk factors include recent soil disturbances, overuse of ivermectin based wormers, a recent change in pasture & being at grass 24/7.

Prevention is based on avoiding changes in management, especially in youngstock, at the ‘at risk’ time of year. Soil disturbances should also be kept to a minimum. Ideally, horses should be stabled for at least part of the day and offered hay or haylage. Furthermore, overuse of ivermectin based wormers should be avoided and ideally, a wormer containing an alternative drug should be used prior to turn out. Co-grazing with sheep or cattle may also be protective.

When a case has been diagnosed at a property,it is of paramount importance to stay calm and to avoid any sudden changes in management. In our opinion, in-contact horses should not be moved field as moving pasture is itself a risk factor for

EGS. Furthermore, fields within a 10km radius are theoretically ‘at risk.’ Co-grazing with a patient that has succumbed to EGS may itself be protective suggesting an acquired immunity. We would; however, recommend that young horses are kept off an affected field during future grazing seasons.

A vaccine trial is currently underway which, if licensed, will hopefully provide us with an effective means of preventing EGS in the future.

Immunity in foals

At birth, foals are immuno-naive meaning that they are born without any protective antibodies (immunoglobulins/IgG) against common ‘bugs’ in their environment.

In order to gain protection, foals need to ingest a sufficient quantity of good quality colostrum (first milk containing high levels of antibodies) within the first 12 hours of life.

It is during this time that foals have maximal absorption of ingested IgG. After this time, absorption rapidly decreases.

Adequate IgG levels are crucial to protect foals from developing infections (namely sepsis). Inadequate levels result from failure to ingest sufficient quantities of colostrum or poor quality colostrum (e.g. when the mare runs milk before birth and loses IgG).

To determine that foals have adequate IgG levels, we recommend measuring IgG using a simple blood test, generally 18-24 hours following birth.

If levels are inadequate then a hyperimmune plasma transfusion is recommended to provide the foal with IgG and in turn protect the foal from developing life threatening infections.

Image source: foalpatrol.com

Tooth decay in horses

Similar to humans, horses’ teeth suffer from decay, referred to as ‘caries’.

Horses’ upper cheek teeth have infundibulae, cup-shaped invaginations in their grinding surface that are normally filled with a hard material called cementum. Sometimes these infundibulae are incompletely filled during development, leaving a cavity for food to settle in and decay. Over time the decay weakens the structure of the tooth, predisposing it to fracture and, if the decay advances beyond the margins of the infundibulum and into the sensitive pulp system, an apical (root) infection may arise. Both of these situations require extraction of the tooth.

Caries of the infundibulae

How can we prevent this?

Infundibular caries cannot be detected by feel, therefore is it imperative that every horse’s mouth is visually assessed using a headtorch during routine dental examinations to detect these before advanced disease develops.

It is possible to perform cleaning and filling of the cavity with filling material. This is termed an ‘infundibular restoration’. We now have the equipment to perform this at our clinic.

To discuss any of our Advanced Dentistry services, please call Sam Baker at the surgery: 01772 861300

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.