Equine Metabolic Syndrome and Human Diabetes Mellitus

Diabetes mellitus is a metabolic disease in which high levels of glucose are found in the blood and therefore in the urine.

In a normal situation the body’s insulin is in charge of regulating glucose levels by moving blood glucose into the tissues where it will be used to produce energy.

When diabetes mellitus is present, it can be due to a lack of production of insulin or a decreased sensitivity of the tissues to it, consequently there will be a failure in the transport of glucose outside the bloodstream. Two types of diabetes mellitus are described:

Diabetes mellitus type I: there is a decreased production of insulin by the cells of the pancreas, so there are low levels of insulin in the blood. This is associated with an immune-mediated cause. It is less common that type-2 diabetes.

Diabetes mellitus type 2: there is not enough production of insulin or the cells become resistant to it.  It appears to be more common in humans than type 1 diabetes.

Although diabetes mellitus is uncommon in horses, there is a condition called Equine Metabolic Syndrome (EMS) that has few similarities with diabetes mellitus type 2. 

The term EMS in horses defines a group of risk factors for the development of laminitis. Obesity is one risk factor. This can be generalised or focalised in certain areas of the horses bodies like around the base of the tail, over the eyes, behind the shoulders, on the crest of the neck. Other risk factors include being a ‘’good doer’’, difficulty in losing weight and abnormal insulin responses.

Obesity is defined by the World Health Organisation as abnormal or excessive fat accumulation that presents a risk to health. Like in human’s diabetes mellitus, obesity in horses plays a main role in the development of EMS. Fat tissue secrete hormones that have an adverse effect and it seems to be associated with the development of insulin resistance, inflammatory conditions and cardiovascular function.

Similarly to human diabetes mellitus type 2, in horses with EMS we find high insulin level in the blood. Insulin levels can be persistently high or have a high response to food consumption which is called post-prandial hyperinsulinemia. The situation where there is a failure of the tissues to respond to the hormone is called insulin resistance. Furthermore, in diabetes mellitus the body frequently fails to produce enough insulin to control glucose levels. Whereas high insulin levels in human associated with cardiovascular disease, in horses the severe complication linked to this condition is the development of laminitis.

The exact process in which laminitis is developed consequently to insulin resistance is not completely understood. However, it is likely to be a damage and constriction of the blood vessels cells that will affect blood support to the hoof as well as a direct damage to the horn cells.

EMS is more common in certain breeds like Shetland, Dartmoor, Welsh and Morgan ponies and donkeys. Like diabetes mellitus type 2 in humans, it is less common in younger ages and it is associated with low exercise lifestyles and high sugar diets.

In both conditions, a presumptive diagnosis can be made based in the presence of overweight and history of related condition like laminitis in the horse. However, final diagnosis of EMS can be made by different laboratory testing.

– Measurement of basal insulin levels. This is achieve by taking a single blood sample. However, it can be normal in some horses so further test will need to be used (as the one described below).

– Testing insulin level as response to feed (Oral glucose/karo test): The horses are fed with some glucose in form of syrup and two blood samples are taken between 60-90 min after. This test will show the presence of post-prandial hyperinsulinemia. There are other dynamics test similar to this that require intra-venous administration of glucose are available but they are less easy to do in the field.

– Other tests that can be helpful in the identification of EMS is the detection in the blood samples of certain hormones like adiponectin which is a hormone associated to fat.

Differently to diabetes mellitus, in EMS glucose levels are not as important in the diagnosis as insulin levels are. However, some of the tests are similar.

For both condition, the treatment and prevention will be directed to management of diet and exercise. Therefore, the goal is to reduce weight and increase insulin sensitivity in tissues and their associated complications. EMS dietary restrictions are based on low soluble sugar and starches. Also exercise schedules are very important. Medical treatment of horses with insulin resistance is currently based on the use of metformine with is one of the drugs used in the treatment of diabetes mellitus type 2. This drug acts at the intestinal level limiting the high postprandial insulin.

As diabetes mellitus, EMS is an important condition with potential severe complications that require prompt detection and management but we are here to help so if you think your horse might have one of the risks factor mentioned before please give us a ring and we will be more than happy to help you.

Mud Fever: The Symptoms and Management

What is Mud Fever?

Mud fever; also known as pastern dermatitis or ‘cracked heels’ is hugely prevalent at this time of year.

As the rain continues to fall our paddocks become inevitably waterlogged and poached, creating the perfect environment for this skin condition to develop.

The mud coats the lower limbs breaking down the skins’ natural barrier. The skin then becomes soft, fragile and prone to damage.

Horses with white legs are more susceptible.

What are the Signs?

Any small break in the skin caused by abrasions from the grit in the mud or sand from arenas enables the bacteria to enter.

The resulting symptoms are heat, swelling and crusty pink hairless lesions around the pastern and heel bulbs.

The bacteria most commonly responsible for this infection is Dermatophilus congolensis. Left untreated infection can spread up the limb causing cellulitis.

This is a painful condition resulting in lameness and swelling of the affected limb.

Prevention is Better Than Cure

Prevention is preferable and keeping your horses’ legs clean and dry is the best way to control mud fever.

However, this is easier said than done at this time of year.

  • Clipping very hairy legs will reduce the accumulation of wet mud around the lower limb and allow better assessment for developing lesions.
  • Managing areas in the field prone to deep mud; particularly around gateways and water troughs. By putting down hardcore or woodchip this will reduce the amount of mud coming into contact with the legs.
  • Hosing legs off on a daily basis is not advised unless they are going to be thoroughly dried afterwards. This process will lengthen the amount of time the hair and skin is damp. Instead, allow the mud to dry and then brush it off.

There are many products available that are aimed at preventing mud fever as they work to protect the skin from moisture.

However these products should not be used if mud fever lesions have already developed as they can slow down the healing process. 

It is imperative that horses’ legs are checked frequently to enable prompt diagnosis and treatment.

My Horse Has Mud Fever, What Do I Do?

If mud fever is identified then bring your horse out of the mud and into a stable or barn.

First clip the hair around the lesions and remove any scabs with a dilute Hibiscrub wash as this will allow more accurate and effective application of treatments.

Thoroughly dry the leg after removing the scabs. If lesions are noticed on more than one leg, then be sure to dry each leg with a different towel, in order to prevent the spread of the infection.

Most of the time mud fever can be managed topically with prescription antibiotic creams such as Flamazine but sometimes oral or injectable antibiotics are required.

Your horse should then remain on box rest or in an enclosed yard/barn area until the lesions have been treated and the skins’ barrier has been restored.

If you are unsure or your horse is lame, then please contact your vet as further investigations or veterinary prescription treatment may be required.

If your horse isn’t responding to treatment then there can be other rare causes of lesions of this nature, particularly if only affecting white haired skin, that may need to be investigated and ruled out. 

The Itchy Horse

Itchy horses can be problematic in many ways. Chronic and/or severe itchiness can have a negative impact on animal welfare, particularly if it affects their rest or appetite. In addition, horses will often scratch enthusiastically on inanimate objects, damaging fencing and buildings. This rubbing can also lead to hair breakage, hair loss and even open wounds. This can lead to permanent scarring – not only unsightly, but potentially career-ending for a show pony. Finally, in extreme cases the horse can be so uncomfortable that it becomes unpredictable to handle and ride, presenting a safety issue to the people around them.

Lice

Lice are wingless insects that live and feed on warm-blooded animals. To identify lice on a horse, part the hair in multiple places over the body and neck – you’ll see the pale, oval-shaped adults moving through the follicles. Winter is the most common time for louse infestations, as thicker coats provide a perfect habitat. Treatment requires topical application of an insecticide, repeated after fourteen days. It is also advisable to remove contaminated bedding, clean stables with a disinfectant and wash rugs and grooming kits.  While lice are not inherently dangerous, their presence can indicate a suppressed immune system. Your vet may advise you to perform further investigations, such as blood tests, to rule out underling disease.                                            

Mites

Mites are distantly related to spiders and, being smaller than lice, cannot be seen with the naked eye. Of the numerous species that can infect horses, the most common is chorioptes – the feather mite. While any horse is susceptible to chorioptes, it is heavily-feathered individuals that display more severe symptoms. This involves stamping, chewing of the lower limbs or rubbing of the lower limbs on objects (e.g. water buckets). Sores can quickly develop as a result of this self-harm.  

Treatment often involves the use of an injectable parasiticide, repeated at fourteen-day intervals.

A number of topical treatments can also be used: these include pig oil and sulphur, topical flea treatments and selenium-based shampoos.

However undoubtedly the most effective adjunct to treatment is removal of the feathers, which disrupts the mite habitat and enables better contact of topical preparations. Stables, rugs and grooming kits should be thoroughly cleaned following treatment to prevent reinfection.

Pinworm

A less obvious parasitic cause of itching is the pinworm. It is a relatively large worm with a unique life cycle.

Females deposit egg packets externally around the horse’s anus and it is the sticky substance that binds the eggs that causes the irritation. The classic symptom of infection is tail-rubbing, and this will often be seen in a group of horses that are in-contact as the condition is readily transmitted between them. Diagnosis can be made by using transparent adhesive tape to sample the skin around the anus. Any eggs collected are then visualised under a microscope by your vet. Treatment can take time due to the species having a particularly slow maturation. It consists of daily washing of the peri-anal area with an appropriate parasiticide solution, application of petroleum jelly to inhibit adherence of the egg packets, and the use of specific wormers to remove adult worms. This is repeated at intervals until fresh tape strips show no more eggs.

Sweet itch    

Sweet itch is caused by an allergic response to the saliva of biting midges. As a result it is very seasonal, resolving completely over the winter months and returning again in spring and summer. The symptoms involve generalised itching, particularly at the face, neck and rump. Initially this presents as broken mane and tail hair, but over time the skin can become thickened and corrugated and hair may fail to regrow at all. Self-induced sores are common.

Unfortunately, sweet itch remains a frustrating disease to treat. The best results are seen when the horse is removed from the source of the problem – the midges. This can be done by tactically grazing the horse at times when midge numbers are low (overnight, windy days) and away from midge hot spots (ponds, trees), plus the liberal use of fly repellents & special sweet itch rugs.

Steroids can be used to control the inflammation very effectively, but there are concerns about long-term effects and it can be very expensive. Some owners report improvement when using anti-histamines, however this has not been replicated in studies. A range of commercial “sweet itch remedies” exist and generally lack any sort of clinical evidence of effectiveness. However, recently the use of in-feed nicotinamides (a form of vitamin B3) has shown some promise when introduced well in advance of the midge season. More research is required to support this. 

Atopy

Atopy is defined as the tendency to develop extreme allergic responses to harmless environmental substances (allergens). These can include pollens, feeds, dust mites, storage mites and moulds. The symptoms include itchiness affecting the whole body and the development of patchy hair loss and sores from intense rubbing.

Diagnosis of the condition is often made based on the symptoms and after excluding other common causes of itchiness. A blood test has also been developed to aid in the identification of the specific allergens a horse is reacting to. An owner can then act to limit contact with these allergens, which, as with sweet itch, is the most effective treatment. Management changes that can assist with allergen avoidance are outlined in the table below.

Allergy causeManagement change
Grasses/weeds/treesExercise on well-cut tracks, roads Remove weeds from yard Fence off trees in paddocks
Dust mitesWash rugs regularly, dry thoroughly and store in air-tight container Buy quality dust-free forage and store carefully Dust stable regularly
Storage mitesEmpty new feed bags into air-tight containers and wash containers between feed batches Rinse feed buckets daily
MouldsMaximise ventilation in stable Treat damp walls with damp inhibitor Keep rugs, tack, feed and forage dry and mould-free

If avoidance of allergens is not possible or is insufficient, steroids may be used to control the inflammation. This works best in cases where the inciting cause is temporary, for example a pollen that is present for only a few weeks, as long-term steroid use is not risk-free.

Finally, a new treatment has been designed alongside the allergy blood test, and this is known as Allergen Specific Immunotherapy. This involves increasing or decreasing the activity of the immune system to give a medical benefit. In atopy, the immune system is over-reacting to something harmless, so it is possible to desensitise the body to these allergens to avoid the resulting inflammation. This is done by injecting gradually increasing doses of the allergens under the skin over a period of weeks, to allow the body to acclimatise to them. The treatment is used widely in dogs and cats with reasonable success rates but is still fairly new to the equine market.

A horse in discomfort due to skin disease can be distressing to see and can lead to owners frantically buying all kinds of lotions and potions in an attempt to relieve the itch. However, most conditions can be easily diagnosed by your vet and an appropriate treatment plan enacted swiftly, giving a satisfying resolution for all. Even for more challenging diseases, your vet will often be able to give hints and tips on management as well as keep you up to date with new research that could result in new treatment options.  

Laser Surgery As A Treatment For Sarcoids In Horses

What Are Sarcoids?
Equine sarcoids are the most common skin tumour in the horse, accounting for 40% of all equine cancers. They are locally invasive tumours which are variable in appearance, location and rate of growth. Sarcoids are caused by Bovine Papilloma Virus, which may be spread by flies. Not all horses that are exposed to the virus develop sarcoids but, it appears that some horses are more susceptible than others. This also explains why horses that have sarcoids will stay susceptible and are more likely to grow additional sarcoids. People are often concerned about whether sarcoids are contagious because of the viral cause. No proof has yet been found that shows horse to horse contact can cause horses to develop sarcoids.
Sarcoids mainly occur around the head and in the groin and axilla area.
They seldom affect a horse’s usefulness, unless they are in a position likely to be abraded by tack. They do not usually resolve on their own and most horses develop multiple sarcoids.

Types of Sarcoids
Nodular sarcoids–are firm spherical nodules found under normal looking skin. They can be variable in size and can become ulcerated.
Verrucous sarcoids–are slow growing, flat scaly tumours that look like warts. They can also look like ringworm or scars.
Fibroblastic sarcoids–are fleshy lumps which often ulcerate, because they grow rapidly. They often occur in clusters and have an irregular shape.
Occult sarcoids–are flat hairless patches that occur mostly around the eyes, mouth and neck.
Malignant sarcoids –highly aggressive and these spread via lymphatic vessels, which results in lines of sarcoids spreading from the original sarcoid.

Diagnosis
Sarcoids can, in some occasions, be confused with other tumours. Although a biopsy can give more information into what kind of tumour your horse has, taking a small sample of a sarcoid can cause the lump to start growing rapidly. Because sarcoids are the most likely diagnosis for these lumps, your vet will most likely suggest complete removal and possible sending the tissue off to a lab for histopathology, which can determine if the lump was in fact a sarcoid.

Treatment
Treatment or removal of sarcoids are not always necessary but, when treatment is required it can prove difficult and possibly expensive. Sarcoids can regrow after treatment and no treatment as of yet is 100 % successful. Success rates vary between types of treatment. It is important to note that every treatment failure , reduces the success rates of future attempts.

-Ligation; where the sarcoid blood supply is cut off, causing it to shrink and drop off over time. Recurrence rates are more then 50%.
-Creams; there are various types, some more irritant to the skin than others and some have to be applied by your vet. They have a success rate of 40-60%.
-Injections; A chemotherapy drug injected into nodular and fibroblastic sarcoids causing the lesions to regress but can cause local swelling and sometimes injections need repeating.
-Radiation therapy; Iridium wires are inserted into a sarcoid to destroy it. It is the most effective treatment method but is very expensive and not widely available
-Laser Removal; is a surgical instrument that cuts into and vaporizes soft tissue with minimal bleeding. The wound that the horse is left with heals very well on its own. This treatment has one of the highest success rates with 80-90 % of horses not re-growing the sarcoid that was treated and, 70% of horses did not develop new sarcoids.
On the rare occasion that sarcoids regress on their own, these horses seem to develop immunity and do not develop further sarcoids. Please talk to your vet for more information on treatment options.

Lawsonia intracellularis infection

Lawsonia intracellularis is a species of bacteria. It can infect a range of animal species but in horses it can cause problems in foals and weanlings. The strain of the bacteria that infects weanlings can also be found in wildlife. These birds and rodents are an important reservoir for infection on horse farms. In all species the infection establishes itself in the intestinal tract, inside the cells of the intestine, as the name states, intracellularis, and it spreads from animal to animal via the ingestion of infected faecal matter. Infection with Lawsonia or Equine Proliferative Enteropathy occurs when the foal ingests the organism and it enters the small intestine where it causes thickening of the intestinal wall. This causes the foal to be less able to absorb nutrients. The damage to the intestinal wall results in protein loss as well.

Symptoms

Foals can become depressed and reluctant to eat. They can have a fever, develop diarrhoea and colic. Because of the protein loss the foal can also develop swollen limbs and/or face. The disease is mostly seen from August to late February and the incubation period is 2 to 3 weeks. Healthy foals will often be able to fight off the infection without any assistance. It is usually the weaker foals that become ill or a period of stress such as being weaned or transported tip the scales and cause the foal to develop clinical signs.

Diagnostics

When a foal is severely ill the clinical signs and the low level of protein in the foal’s blood will often be enough to rouse suspicion of Lawsonia infection. An ultrasound examination will provide further evidence when showing thickened small intestines. Faeces can be tested for the presence of bacterial DNA. This test is known as a PCR test and is very helpful in confirming the infection in sick foals. Another test that can be performed is based on the identification of antibodies (proteins made by the infected animal’s immune system as it tries to fight off the infection) against Lawsonia in a blood sample.

Treatment

Foals can be treated with antibiotics. Some severely ill foals will need intensive care to receive fluids and extra support when their protein levels are low. An infection with Lawsonia can dramatically affect the weanlings growth preventing them reaching their predicted height.

Prevention

Thought should be given to where the infection could have come from and if there are rodents or birds that could have introduced the bacteria. Ideally the foals would be kept away from these possible sources and a foal with an infection should be kept away from the rest of the young stock. There is a vaccine that could possibly help to reduce the prevalence of the Lawsonia but this is for now still an unlicensed product.

 

Glanders (Farcy)

Glanders is one of the oldest known diseases of the horse. It has now been eradicated in the United Kingdom and much of the world, although it is still reported in the Middle East, Pakistan, India, China, Brazil and Africa. The disease is caused by a bacterium called Burkholderia mallei and is a zoonosis, that is, infectious to people, with a 95% fatality rate, if untreated.

The disease is characterised by nodules or ulcers on the skin and in the respiratory tract, but is more often seen in a chronic or latent form. These chronically infected horses act as a reservoir of disease. Glanders is contracted by ingestion of food or water contaminated with nasal discharges of carrier animals or by ingestion of contaminated meat from infected horses. After an incubation period of 3 days to 2 weeks animals can develop acute or subacute respiratory symptoms or cutaneous symptoms.

Acute respiratory glanders is mainly seen in asses and mules,who are most severely affected. Symptoms include high fever, cough, nasal discharge and ulcers on the nasal mucosa. As the disease progresses respiratory signs develop and the animals often die.

The chronic disease is more often seen in horses and is commonly seen with both the cutaneous and respiratory forms, symptoms are slower to develop. In the respiratory form symptoms include; ulcers in the nasal passages, with nasal discharge, chronic pneumonia and scaring of the submandibular lymph nodes. In the cutaneous form (‘farcy’) nodules appear to course along the lymph nodes and degenerate to form ulcers that discharge a highly contagious sticky pus. The liver and spleen may also develop similar nodules.

Clinical signs develop when the disease is well advanced so diagnosis is best made by the use of diagnostic such as CFT antibody test or PCR test of infected skin tissue. Treatment of Glanders with antibiotics can be attempted in endemic countries, but often results in latent disease. In counties where Glanders has been eradicated, animals with confirmed disease are euthanased and  in contact animals are tested to monitor disease status.

Heart Murmurs

There are four valves in the heart, one between each atrium and its respective ventricle and one between each ventricle and the major vessel it supplies. A valve is a thin flap of tissue that opens and closes to let the heart fill and empty at the appropriate time. The opening and closing of the valves generate sounds and those are the heart sounds your veterinarian will be listening for with a stethoscope. A ‘heart murmur’ is an extra sound audible when listening to a horse’s heart, next to the normal heart beat.

Most murmurs that we find are ‘flow’ murmurs, which means that these murmurs can occur in completely healthy hearts which no significant abnormality but are caused by normal flow of blood. These flow murmurs happen in horses because they have a large heart compared to their body size, so there is a lot of turbulence in blood flow that can be audible as a murmur. These murmurs have no clinical significance.

However, some murmurs do indicate an abnormality in either blood flow or heart function. They can either mean a leaking heart valve, thickening or narrowing of a valve or large blood vessel or an abnormal hole between different heart chambers. A valve can start leaking for a variety of reasons. The most common cause is degeneration of the valve leaflets with age. They can become thickened and shortened. When this occurs, the valve leaflets cannot come together properly. Another reason for the occurrence of a murmur can be altered blood viscosity.

A thorough examination and listening to your horse’s heart will give us a better idea what kind of murmur your horse has. By determining the location of the murmur, the length, the volume and when the murmur is audible, the murmur will be graded. The grades run from 1, which is a very quiet murmur, to a grade 6 where the murmur can be heard without even touching your horse’s chest with the stethoscope.

Next to the murmur itself, the presence of any other clinical signs is important. Clinical signs of heart problems/failure could include exercise intolerance, weight loss, oedema and enlargement of blood vessels, mostly visible as a very clear visible pulsation in the jugular vein. If the murmur is severe or there are any other clinical signs, further investigation is required.

An ultrasound examination of the heart would be the first step. This allows for the heart to be imaged while it is beating. This is a specialised technique and your horse will have to be referred to a specialist. An ultrasound examination is also typically recommended for the evaluation of some murmurs detected at purchase examination, especially for horses intended for athletic use. The ultrasound will show the nature of the lesion causing the murmur to be identified, next to measuring the size of the chambers of the heart and the contractility of the heart. All these factors combined will give an indication of the severity of the murmur and the likely effect it will have on your horse. The examination will also provide a baseline; we may recommend a repeat examination in 6-12 months to note any progress of disease. Some lesions remain static for a number of years, and the horse can go on to work for several more years with no problems. However, if the problem appears to be progressing, it may be advisable to retire the horse.

Other tests that could be performed would be a blood test to tell if there is any damage to the heart muscle and an ECG or electrocardiogram to look for abnormalities in heart size and heart rhythm.

Much research has been conducted into the frequency of heart murmurs and they are a common finding and most do not seem to be clinically significant. With a thorough examination by your vet, decisions can be made if there are further investigations needed, or if the murmur is likely to be of no clinical significance.

Lymphangitis

This disease is recognised by the swelling of the legs, usually hind, that pits when pressed with a finger. There are two causes with very different implications for the horse.

The first reason for this type of swelling is known as Sporadic Lymphangitis. The swelling usually affects both hind limbs but can affect all four legs and can be considerable. The cause is simple and it is brought on by an unusually lengthy period of box rest in a horse that doesn’t usually rest for long periods. If your horse is stabled for most of the time anyway then swelling of the lower limb is likely to be due to a genuine injury rather than this disease. This sporadic form can easily be differentiated from the more sinister form as it resolves to a completely normal looking leg with a short period of exercise. There is no underlying disease process and there are no long-term effects to the affected horse. As the colloquial term “Monday morning disease” suggests, it is commonly seen in horses that work hard through the week and are stabled over the weekend, presenting with swollen back legs on Monday morning when they are brought out to work again.

The other form of the disease – Ulcerative Lymphangitis – is a completely different disease. This presents similarly to Sporadic Lymphangitis with massive swelling of, usually, one hind limb but it is much more painful and you will often see discharge through the skin of the affected leg. It is caused by infection with bacteria either through an existing wound or in a limb affected by mud rash. The swelling is caused by a combination of inflammation and blocked drainage of the leg by small clots wedged in the vessels that would normally carry the oedematous fluid away. The affected horse will also often be non weight bearing, show a high temperature, reduced or absent appetite, sweating, increased respiratory rate and sometimes, mild colic symptoms due to the significant pain.
Treatment is always necessary and should be rapid and aggressive as these cases are difficult and challenging to treat successfully and unfortunately often results in a permanently swollen leg.

Uveitis

Uveitis (other names include moon blindness and periodic ophthalmia) is a painful and potentially very serious condition – it is the most common cause of sight loss in horses. Uveitis simply describes inflammation within the eye, this affects three different parts of the eye – the blood
supply to the eye, the muscles controlling the diameter of the iris, and the iris itself.

This inflammation can be initiated in a number of ways, and any damage or irritation to the eye can initiate a reflex inflammatory response. This includes physical trauma, and corneal diseases such as ulcers. Uveitis can also commonly be immune-mediated (especially in Appaloosas), and may affect
one or both eyes recurrently. Geographically, the causes of uveitis vary greatly, and some of the infectious causes that commonly affect horses in other countries are currently being investigated in the UK.

Clinical Signs
The most common signs that your horse may display are squinting, watery discharge, rubbing his eye and being uncomfortable in bright sunlight. On closer inspection, the inside of the eye may appear “hazy”, you may also notice that the pupil appears very small and narrow, even in a dark stable.

Treatment
It is important that every painful eye is examined by a vet as soon as possible, as some diseases may present similarly but require very different treatments.
The mainstay of treating uveitis is using anti-inflammatory drugs to reduce inflammation and pain. We will prescribe steroid-based eye drops for you to administer daily, and in addition to this we will put drops in the eye to dilate the pupil.
This is because the inflammation causes the muscles controlling the iris to go into spasm – these drops relax the pupil and relieve the pain caused by this spasm. Often the horse will be given oral pain relief. We may recommend that you continue treatment for a few weeks past resolution of the clinical signs.

Managing a Horse With Uveitis
It is important to keep the horse in a darkened stable, especially if eye drops have been given. This may then progress to being turned out in a good quality UV protective fly mask. It is important to monitor a horse who has had uveitis, as very often it may be part of a syndrome of recurrent disease. For horses that suffer from repeated episodes of immune mediated uveitis further treatment options are available, including surgical implants that release drugs within the eye to prevent the horse’s immune system from causing uveitis.

Long Term Problems
It is important to try to control uveitis, as if it remains untreated significant damage can be caused to the eye, and can ultimately result in total vision loss. When a horse is vetted, the vet will carefully examine the eyes to look for previous signs of uveitis.

The picture shows a Miniature Shetland whose uveitis was uncontrolled after a blunt trauma to the eye. The pale disc you can see is the Optic Disc – which is the head of the nerve connecting the retina to the brain!

Sweet Itch

Sweet itch is a skin disease caused by an allergic reaction to the saliva of culicoides species (midges), characterised by intense itching. After an allergic horse is exposed to the saliva the immune system will produce an excess of histamines similar to that of people suffering from hay fever. This is an ‘over the top’ immune response resulting in swelling and intense itching of the skin causing the horse to rub and chew at the area affected. The most severely affected areas tend to be along the mane and tail base resulting in the horse rubbing out large sections of hair to leave thickened, rough, hairless and often raw skin. The skin can then become infected thus making the condition worse. Signs can start at a very young age and tend to become more severe year on year although some horses can develop the allergy later in life. It can be a very debilitating condition throughout the warmer months when the midges are most active and affected horses can become very miserable.

Management

As this is an allergic condition it only takes a few midge bites to trigger the symptoms and the key to control is reducing/preventing attack. A number of management changes should be implemented:

  • Environment – Midges breed on wetland/near water sources and woodland. Susceptible horses should avoid these areas. A windy hillside is best for keeping midges away!
  • Stabling – Midge activity is highest at dawn and dusk so stabling susceptible horses from 4pm until 8am during the summer is best. You can fit fly screens to the stable door and use insect repellent strips to ‘midge-proof’ your stable. A fan in the stable creates air movement so keeping midges away as they cannot fly against a wind stronger than 5mph.
  • Rugging – placing a full body lightweight sheet on your horse including hood, tail cover and belly protector will prevent midges from biting.
  • Fly repellents – should be applied liberally particularly along the crest, spine, tail and head especially when riding your horse. There are many products available (some more effective than others!) SWITCH and DEOSECT can be very effective and don’t need applying everyday.

Treatment

Despite your best efforts at prevention many horses still get ‘sweet itch’ and it is important to discuss treatment options with your vet.

  • Topical creams – those containing steroids and anti-histamines can be of use, they can expensive longterm but judicious use can help to alleviate symptoms.
  • Anti-histamine tablets – sometimes of use but often ineffective due to severity of allergy
  • Steroid treatment – injection with steroids helps to reduce the immune response to the insect bites and long acting preparations can give several weeks of relief. Steroid treatment does not treat the underlying condition but merely relieves the itch. It should be used with caution at the lowest possible dose due to potentially serious side effects including laminitis, however sometimes it is the only option to relieve the horses discomfort.
  • Cavalesse – this is a natural food supplement containing vitamins and minerals which have a specific effect on the immune system within the skin. A key ingredient, nicotinamide, acts to reduce the production of histamine (which causes the itch) and to improve the skin oil barrier by increasing the amount of natural fats at the skin surface, thus acting as a natural barrier to midge bites. This product works best if treatment is started at least a month before the allergy season and continued throughout the risk period.