Ragwort

Ragwort (also known as Senecio Jacobaea) toxicity is one of the most common causes of poisoning to horses in the UK. A recent survey by the British Horse Society showed that 20% of respondents knew of a horse that had been affected. Toxicity is caused by substances in the plant called Pyrrolizidine alkaloids. The effect is cumulative and symptoms may not be seen for up to a year after exposure. The poison effects 3 main body systems - the liver, the central nervous system (brain, spine and its associated nerves) and the skin. Symptoms include weight loss, loss of appetite, depression, diarrhoea, jaundice (yellowing of the whites if the eyes and gums) and constipation. Neurological problems can be seen as wobbling and dizziness, pressing the head against the wall and the appearance of walking aimlessly. Toxic compounds can also enter the skin causing it to become particularly sensitive to sunlight resulting in crusting on white areas that looks like sun burn. This process is called Photosensitisation.

If you’re concerned your horse may have been affected please contact your vet. Blood tests can be used to confirm liver damage but cannot test specifically for the poisoning. A sample of tissue taken directly from the liver may be able to confirm the damage is caused by Ragwort. Horses diagnosed with poisoning rarely recover. Treatment is mostly supportive with nutrition to maintain condition and medications to control the symptoms.

Control of ragwort is crucial in avoiding illness. The first step is the identification of plants. For the first year of life the plant is a small dark green rosette. In subsequent years it becomes the characteristic bright yellow flowers between June and October. Ragwort cannot be entirely eliminated from the UK as it forms an important part of the ecosystem. However, the Weeds Act 1959 made ragwort control a legal obligation for owners and occupiers of grazing land. Those who keep their horses in livery and are unsure of their responsibility in ragwort control should check their contract.

Cutting of ragwort plants is only suitable in emergency short term control to prevent seeding. Cutting the stem stimulates growth and will cause the plant to re flower later in the season. If removing plants by hand, they should be pulled up or levered out by the roots. Ensure the entire root is removed as any left behind will re-grow. Ragwort is best pulled early in the summer before flower heads mature and when the ground is wet. As well as removing adult plants it is important to identify first year rosettes to prevent them seeding the next year. Ragwort is toxic to all species including humans so gloves and long sleeves should be worn. Any skin exposed to the plant should be thoroughly washed in warm soapy water. Once pulled the plants are still toxic and may still seed, in fact wilted plants are more palatable to horses. It is essential all plants are collected and placed in sealed boxes or bags. Disposal can be by incineration, rotting or removal by a waste-management company. The plants should never be composted, placed on the muck heap or transported without being properly sealed in bags.

It is possible to use herbicides as part of a ragwort control strategy although it must be considered that one application does not guarantee total removal. Most products require application in the spring to the growing rosettes and a calm dry day. When choosing a product thought must be given to the environmental implications and proximity to water sources which may become polluted. If spraying you will need a suitably trained person and the means to correctly dispose of unused chemicals. Horses must be moved off the pasture for application and for a period of time afterwards. The manufacturers of pesticides will make recommendations on when it is safe to use the pasture but it is the keeper's responsibility to ensure all dead ragwort is fully wilted before exposing to horses. For a list of approved pesticides please see pesticides.gov.uk.

Ragwort thrives in areas of poorly kept grassland so plant numbers can be reduced by improving pasture management. This includes not over-gazing, adequate manure removal and removing uneaten stale hay. Poaching the ground should be avoided wherever possible as bare patches are ideal for ragwort growth. Co-gazing with sheep can be beneficial as they are far less susceptible to ragwort poisoning than horses and will eat the young first year rosette plants.

For any advice on ragwort control or if you think your horse may be affected by poisoning contact The Arundel Equine Hospital on 01903883050.

Written by Rebecca Dobinson, BVSc, MRCVS

Cushings & EMS

Cushings (Pars Pituitary Intermedius Disorder ((PPID)) and Equine Metabolic Syndrome (EMS) are the two most common metabolic/hormone disorders of the horse and pony. In general, Cushings affects older horses, whereas EMS first develops in young and middle-aged animals. Although they are two separate conditions, they can overlap. All breeds are susceptible but ponies are most at risk.

Cushings

This is due to a dysfunction in a small area of the horse’s brain and it disrupts the normal balance of hormones, mainly affecting ACTH and cortisol (stress hormones). The most common sign are your horse developing a long, thick, curly coat or not losing his/her winter coat. Other early signs of Cushings are vague but include; reduced performance, lethargy and regional fat deposits (bulging supraorbital fat pads, shoulder fat pads, “cresty neck” and fat accumulation around their tail base). The more advanced signs of the disease include; muscle wasting, a pendulous abdomen, sway back, increased sweating (linked to not shedding their coat), blindness, recurrent infections (including parasites, skin infections and synovitis), reduced fertility in mares and increase drinking and urination.

The most import aspect of this disease is laminitis; this can feature early on in the disease process and is usually the condition, which leads to diagnosis of Cushing’s. Laminitis is an inflammation and breakdown of the lamellae. The lamellae suspends and supports the pedal bone within the hoof capsule. When these lamellae are disrupted, the pedal bone sinks and rotates which then causes lameness. Cushings causes a break down in the lamellae proteins and reduces lamellae blood flow. This is why horses with Cushings are predisposed to laminitis.

Diagnosis is usually made on history and clinical exam; however, to be sure a blood test is usually conducted. The blood test measures the hormone ACTH as horses and ponies with Cushings have significantly higher levels of ACTH. It is not 100% diagnostic and may miss early cases but will confirm most and gives you the ability to measure the success of treatment. The hormone ACTH usually peaks in the autumn naturally and so this is the best time of year to test horses suspected of having Cushings. When determining baseline ACTH concentrations it is important to consider that stress may increase ACTH levels so the horse must first recover any bouts of stress or laminitis. Other tests are available if the result of this test does not match with the clinical picture of the horse.

Cushings is a condition mainly of older horses and so management is vital, including; feeding high-quality foods, regular dental care, deworming, and farrier care. Management and treatment depends on severity of condition, if the horse has a hairy coat then you can manage them simply with regular clipping. However, if the horse or pony is suffering from laminitis then management and pharmacological intervention will be required.

Pergolide ‘Pracend’ is the first-line treatment of horses and ponies with Cushings, it is a lifelong treatment that needs to be coupled with management changes. Once a treatment has been started, if there are no signs of improvement after 4 to 6 weeks, the dose should be increased gradually every 3 to 4 weeks. Treatment should be monitored by assessing both improvement of clinical signs and repeat blood tests to check for normalisation of ACTH concentrations. Most horses show improvement within 6 to 8 weeks of treatment. Within a month you can expect to see an improved attitude and reduced lethargy, however improvements in coat, muscle mass and laminitis may take up to a year. This is a lifelong management that needs to include laminitis management as well.

EMS

This occurs because fat tissue is active and produces its own hormones. These hormones reduce your horse’s response to insulin, making your horse insulin resistant (IR) this leads to a high concentration of both insulin and glucose in your horse’s blood stream (it also increases the level of cortisol, like in Cushings). This condition in very basic terms can be considered “Horse Diabetes” with a bit of Cushings. These horses are usually obese or “good doers” however, some horses can be lean but still have EMS.

EMS is characterised by obesity or regional adiposity, insulin resistance (IR), and subclinical or clinical laminitis. Laminitis is the most important component of EMS; this condition is most difficult to manage. IR predisposes a horse to laminitis by; altering blood flow and reducing nutrient delivery to the hoof tissues and generating inflammatory or oxidative damage. EMS horses therefore cannot tolerate normal laminitis triggers such as; grass rich in sugars and starches, grazing on abundant and rapidly growing grass, grazing after a frost or in periods of cold night and warm days (this changes the sugars within the grass and they become more readily available).

Diagnosis is made on clinical examination and history but there are blood tests that can confirm the diagnosis and again it is good to have a base line from which to judge the success of treatment. To diagnose EMS in horses, insulin and glucose concentrations can be measured in a blood test. Horses are starved for 6 hours over night and a blood test taken in the morning. Stress raises insulin concentrations in horses so it is important not to take a blood sample whilst the horse is suffering from laminitis. Another test available is an Oral Glucose Test, the horse is starved overnight for 6 hours then a blood sample is taken in the morning before giving a high glucose feed (1g/kg) in a very small feed. After this, blood samples are collected 2 and 4 hours later.

Management of IR/EMS involves mainly weight loss and laminitis management. This can be achieved by reducing sugar and starch intake, soaking hay, removing fat supplements, restricting turnout and regular daily light exercise. Exercise when the horse is sound is essential as it can decreases IR. Leaner horses with EMS are challenging to manage from a dietary standpoint because more calories must be provided without exacerbating IR. Most horses or ponies with EMS can be effectively managed by controlling the diet and reducing body fat, however, it takes time for these management changes to take effect, so drugs such as Metformin can aid the process and accelerate the improvement if the patient suffers from recurrent laminitis.

For both these conditions, the horse needs to be treated as an individual so close work with your vet and farrier is essential in successful management. If you have any concerns, your horse or pony may be suffering from Cushings or EMS then contact your vet for a consultation.

Navicular Bursar

Once a diagnosis of a problem with the navicular bone, the deep digital flexor tendon or one of the other soft tissue structures associated with the navicular bone is made, one of the treatment options is to inject the navicular bursar with cortisone as an anti-inflammatory. The navicular bursar is the fluid filled pouch between the navicular bone and the deep digital flexor tendon.

The procedure involves injecting with a long needle between the heel bulbs, through the deep digital flexor tendon and into the navicular bursar. This is best carried out under x-ray guidance. First of all a radiograph is taken of the foot with a marker that shows up on the image, to identify the exact location of the navicular bone within the hoof, a mark is made on the hoof wall with a marker pen to be used as an aiming marker for the needle advancement. Often a nerve block will be placed at the palmar digital site to totally desensitise the heel region of the foot, sometimes just the location of the injection site is desensitised with local anaesthetic.

Once the injection site is desensitised the heel region is meticulous cleaned and then aseptically prepped. A 10cm spinal needle with a stylet is placed through the skin between the heel bulbs and advanced towards the navicular bone, roughly parallel with the ground, using the marker on the hoof wall as a guide to the angle of approach. As the needle is advanced it is possible to gently feel it contact the back of the navicular bone. At this point a second radiograph is taken to make sure the needle placement is correct. If the needle is in the right place behind the navicular bone and through the deep digital flexor tendon, then the stylet is removed from the needle and the cortisone is injected into the bursar. Mixed in with the cortisone is a radiopaque substance which shows up on x-rays, a third x-ray is taken to demonstrate filling of the drug within the pouch at the back of the navicular bone and therefore the drug within the navicular bursar, after the needle has been removed.

Following injection the heel region is bandaged to keep it clean for 24 hours. The patient is kept box rested also for the first day after the injection, then hand walked for a further 2 days, followed by an ascending exercise program dependent on what the actual diagnosis was.

It is important that this procedure is carried out as aseptically as possible as to avoid the introduction of infection into the navicular bursar. It is also important to be as accurate as possible with the needle placement, if we know from the series of images obtained that the needle was correctly positioned and that the cortisone was injected into the navicular bursar, then we know if the horse does not become sound it was not due to inaccurate drug placement and that a different treatment option is required.

Navicular bursar medication is only one treatment option available to us for the treatment of navicular disease syndrome. This technique should be used in conjunction with other medications such as Tildren (Equidronate), aspirin, isoxoprine, etc. Probably the most important aspect of treatment is the farriery and obtaining a correct and appropriate foot balance.

Dr. E.A.Lyall, BVetMed, CertEM (StudMed), MRCVS

New Born Foal Facts!

  • Suck Reflex should be present within 5-10 minutes of birth
  • Trying to stand within 30 minutes
  • Standing within approximately 60 minutes
  • Suckling within 2-3 hours (If not by 4 hours -call the vet!)
  • The best time for colostrum absorption is the first 12 hours
  • Should suck 5-7 times an hour
  • Will consume 10-15% of their bodyweight in milk in the first 24 hours.
  • This increases to 20-25% by a few days of age.
  • Meconium should be passed within the first 6 hours of life.
  • First urination is 6 hours for colts and 10-12 hours for fillies.
  • The umbilical stump should shrivel up within 24 hours.
  • Vet check at 12-18 hours of age

Foaling The Mare

Foaling the Mare
Most mares foal without complication, however it is important that they are monitored regularly as the foaling becomes imminent.  Mares prefer to foal when all is quiet, as such it is important that the checks do not disturb them.  The stable can be fitted with a low wattage light bulb that can be left on.  Small cameras are available so that foaling mares can be observed from a distance and sweat alarms can be used to indicate an imminent labour.  There are alarms that can be stitched into the vulva which call your mobile phone when the water bag is pushed through the vulva at the onset of labour.  In high-risk mares with complications, the milk secretions can be monitored to more accurately identify when labour is likely to begin. 

The mare herself will start to show signs impending foaling.  These may occur several weeks before foaling or may start much closer.  The signs include development of the udder, swelling in front of the udder, slackening of the pelvic ligaments resulting in hollowing and softening of the quarters, lengthening and relaxation of the vulva, changes in temperament and the production of wax on the teats.  The “waxing-up” of the mare is one of the last signs to occur. 

During the last month of pregnancy the udder produces the first milk, colostrum, this is rich in antibodies that protect the foal from infection.  Prior to foaling some mares drip or run milk and as a result lose the valuable colostrum, once lost it is not replaced.  If this occurs 200ml volumes can be milked from the mare and frozen, this stored colostrum can be thawed in warm water (not microwaved) and bottle-fed to the foal in the first 6 hours after foaling.

While a mare is foaling it is better to minimise interference and to only respond when there is a problem.  There are three stages of labour.  The first stage is when the foal is getting into the correct position to be born, this may take several hours.  During this time the mare may become restless, sweat, look at her flanks and get up and down.  The second stage of labour begins with the passing and breaking of the white water bag, it ends with the complete birth of the foal.  Ideally mares should foal lying down.  The second stage of labour involves the forceful uterine and abdominal contractions required to give birth to the foal, typically the mare will be lying on her side. The average length of the second stage is 17 minutes, if after this length of time when forceful expulsive efforts have been made and the foal has not been produced veterinary assistance should be sought. The third stage of labour involves the passing of the placenta.  Once the mare stands after foaling the placenta should be knotted at the level of the hocks to prevent the mare from standing on it.  The placenta is usually passed within one hour, if it is not passed within three hours veterinary assistance will be required.  The placenta should be kept for your vet to examine.

Most mares will foal without any complications.  The normal presentation is that of a diving posture where the two front feet and the head come together, so the first part of the foal to be seen will be a hoof, usually followed by a second hoof a little further back.  The soles of these hooves should be facing the ground, if they are facing upwards the foal is either rotated or it is breach and coming back feet first which is very unusual.  A rotated foal will end up in the correct orientation as the mare gets up and down, so let her do this.  The leg with the foot which is a little further back will have a flexed elbow, the elbow may catch on the brim of the pelvis, if the mare appears to be making little progress getting the foal out, then between the mare’s contractions grip the pastern on the shorter leg and pull the limb to the same length as the more forward hoof, this will extend the elbow and prevent it catching on the pelvis.  Once this is corrected often the foal will come away easily.

As well as two front legs there should be a nose, this should be at about the level of the foal’s mid canon on the forelimbs.  Once the nose is out of the vulva it is worth just clearing the membranes from the nostrils.  If little progress is being made by the mare a little traction can be put on the foal to help it out, the direction of pull should be down towards the mares hocks due to the shape of the birth canal and the posture of the foal.  Grasp the pastern regions and pull gently, particularly between the mare’s contractions to prevent the foal slipping back into the uterus, let the contractions push the foal out, just help her.  Once the foal gets it’s chest and then pelvis through the mare’s vulva it will come away very easily.  Ideally the foals back legs should be left in the birth canal and the mare allowed to lye quietly to regain her strength, in this position the foal will still remain attached to the placenta via the umbilical cord, during the time it lies here blood from the placenta will be retained by the foal.  The placenta should break at the natural weak point next to the foal’s abdomen when the mare stands up.  As the foal is lying there make sure the nostrils are clean, sit it on it’s chest with it’s front legs wide apart in front of it and rub it’s chest with straw to stimulate breathing.

If at any stage in the birth process there are concerns about the foals presentation or it’s viability then seek veterinary assistance immediately.

Respiratory Conditions

Diseases and Disorder of Youngstock – Respiratory Conditions
(By Ed Lyall, BVetMed, CertEM (StudMed), MRCVS)

Young horses are like children where they have quite naïve immune systems meaning they can pick up viral and bacterial infections much easier that an adult horse. Many of these manifest themselves when the antibodies, derived from the mothers colostrum, start to disappear from the foal’s blood stream. The most common infections are respiratory infections; it is not unusual to see paddocks full of weanlings with crusty snotty noses on stud farms, they are usually caused by viruses.

There is little treatment for respiratory viruses in horses other than supportive care, ideally the youngsters affected should have their temperature monitored and non-steroidal anti-inflammatory drugs such as bute can be given to bring the temperature down to normal.

Any foal with a snotty nose and a high temperature should be monitored for the development of swollen painful glands under the jaw and around the base of the ear. If such swellings are present, tests should be performed to rule out strangles, the bacterial respiratory infection caused by Streptococcus equi. Young horses often have slightly enlarged glands where their immune system is learning to deal with all the pathogens that the horse is being exposed to on a daily basis. The difference is that strangles causes abscesses with the glands that are very painful to palpate. Any horse, and its contact companions, that are suspiciously looking as though it has strangles should be isolated until the results of the appropriate tests are through.

Rhodococcus equi is a bacterial disease that causes abscessation in the lungs of young foals. It is derived from inhaled environmental bugs and can affect multiple foals on the same property, typically from two months of age. Foals will be found to be dull and lethargic with reasonably high temperatures, severe cases will be breathing difficulty; blood samples will show elevation of white cell counts and more importantly elevation of fibrinogen levels.

The diagnosis is confirmed by ultrasound scanning the chest to find evidence of the abscesses. Treatment is with appropriate long term antibiotics.

Caring for the Young Horse

Caring for the Young Horse

(Redworms)

It is important to monitor worm egg counts and to appropriately treat with anthelmintics. Young, growing horses are more susceptible to intestinal parasites than adult horses as the immune system is responsible for keeping worm burdens down in the bowel. They are also more likely to have colic due to the presence of tapeworm in the bowel, and these cases can require surgery to correct because the tapeworms cause the bowel to contract in an uncoordinated fashion.

Small red worms, cyathostomes, can cause very bad diarrhoea, typically in the autumn when the larvae go into hibernation in the bowel wall, the encysted larvae emerge from hibernation and leave the bowel wall, causing a lot of trauma to the tissue.  Diarrhoea caused by worms can be very difficult to treat and can result in a rapid debilitating loss of condition in young horses.

Teeth can become very sharp, and problems with milk teeth/caps, are commonly seen. Poor conditions and difficulty chewing would indicate that an examination of the mouth and a quick rasping session would be appropriate.

As young horses are developing it is important to keep a close eye on their limbs to make sure they are developing properly. Hard ground and rapid growth rate can cause various problems. Boxy feet can develop quickly and can easily be missed if the animal is turned out in long grass. The deep digital flexor tendon is effectively too tight, pulling the foal up on to the tip of its toe, which is then worn away, resulting in a boxy conformation. Many of these cases can be corrected with some remedial work by the farrier, heel trimming and applying a toe extension. Some require surgery in conjunction with farriery, to cut the check ligament of the deep digital flexor tendon, or in extreme cases the deep digital flexor tendon itself can be cut. Even after surgery these youngsters will have a normal athletic career.

The most common cause of lameness in young horses is foot abscesses, however, it is important to look at lame youngsters and make sure they do not have swollen joints, so that problems to do with health and limbs can be picked up and dealt with at an early stage.

A preventative health care programme should include regular and appropriate worming, vaccination against influenza and tetanus, regular assessment of the limbs and feet with the farrier and monitoring of weight, body condition and growth rate. Most of the feed companies have nutritionists to advise on feeding of young stock, and your vet will assist in the assessment of the limbs if you feel there is a problem.

Coping with Sweet Itch

Coping with SweetItch

 

(By Pauline Williams, BSc, MSc,MA,VetMB, Cert EM (Int Med), MRCVS)

 

Sweet itch is a skin condition caused by an allergic reaction to midge bites (primarily Culicoides spp). It is also known as insect bite hypersensitivity or summer seasonal recurrent dermatitis, and can affect horses, ponies and donkeys all over the world according to the distribution of midges.

All animals are bitten by midges but only those that are allergic to the bites show clinical signs. There are different species of Culicoides which feed at different sites; some at the mane and withers, others at the tail and or belly and legs. The animal may be allergic to one or more species and therefore they may show signs on one area only, such as the tail or all over the body in severe cases.

Clinical Signs

Affected animals show varying degrees of pruritis (itchiness) which leads to self-trauma due to rubbing. The most common sites affected are the mane and tail but sometimes only the belly is affected and in severe cases the animal may show signs of all over the body including the legs. Rubbing leads to alopecia (hair loss), ulcers and bleeding with secondary crusts (scabs) and infection. Many of these changes are reversible out of season when there are much fewer midges. However in more chronic cases the skin can become hyper pigmented (blackened) and thickened with ridges, especially along the mane. Severely affected animals may lose weight due to chronic irritation and show behavioural changes from tail swishing, rolling, and rubbing the belly on the ground to being unrideable at the peak midge feeding times of the day (dusk and dawn).

If you are buying a pony that is said to be managed successfully by one of the different treatment options, you should be aware that a change in location may either improve or exacerbate the condition to a point that it is no longer manageable. Sweet itch sufferers may also deteriorate with age.

When buying a pony in the winter out of the midge season, in severe cases the thickening on the neck and tail head may still be evident. However, it is often difficult to detect animals which show milder signs or those that have been managed effectively through the summer. Often there is evidence of different hair length, particularly at the tail head, but it is important to ask the owners to declare if the pony suffers from the condition. At present, there is no reliable blood test or other allergy test to detect sweet itch sufferers out of season, but research is on-going.

Identifying Joint Disease

 Identifying Joint Disease

Joint pain can be mild to severe; even mild joint pain that is unnoticeable in terms of lameness to the rider can be performance limiting. A sore joint may stop a show jumper landing on the correct lead after the fence or it may cause the horse to roll unnecessary poles of higher fences. A dressage horse may show asymmetry of limb action during complex dressage movements. Polo ponies may find it difficult to stop and turn sharply and race horses with joint pain may be slower than their expected potential. Joint pain is as a result of joint inflammation, so left untreated some inflamed joints will settle down with rest. Some chronically inflamed joints go on to become osteoarthritic. Early identification of joint inflammation and appropriate treatment can reduce the chances of chronic joint pain and therefore poor performance and lameness issues.

 

Often riders will call and say they think there is a problem with a horse, and I now look at higher level competition horses on a regular basis to monitor for joint pain. The first thing is to ask the rider to describe the problems they think they are having. I then palpate the horse’s limbs for obvious filling of the joints, as in most cases an inflamed joint will have an effusion, which is where the inflamed lining of the joint produces an excess amount of fluid. Some effused joints can be identified by visual inspection as the joint bulges. In some instances, particularly with the fetlock joint, it is possible to feel a palpable thickening of the joint capsule. Some joints will feel warm to the touch.

 

The next step is to trot the horse up on a firm flat surface and see how it moves. One of the advantages of regular checks is the vet gets to know what it normal for the horse and is then able to spot subtle gait changes. Flexion tests are a valuable way of identifying a problem with a joint, most inflamed joints will result in lameness after flexion test. The horse will then be evaluated under saddle, on the lunge in a school and on a hard surface. The rider will be asked to demonstrate the problems they are having, this may be during complex dressage movements or jumping obstacles.

 

Often it is possible to identify a specific joint causing the problem by clinical examination, but a lot of the time it is necessary to anaesthetise or block sequentially joints on the limb in question. Once a joint is blocked the horse is put back in the situation that demonstrated the lameness the best, i.e. on the lunge, on the hard or flexion test. Often there is little for the vet to visually see and the response to blocking must be assessed by the rider.