Month: July 2015

Tuesday 15th July

After we finished lecturing in Helsinki it was back to the port and onto another overnight ferry to Stockholm. We were crammed into windowless cabins (four of us per cabin) in the bottom of the boat next to the engine rooms and it was a relief to reach Stockholm. The approach to Stockholm by water is beautiful with hundreds of small islands each with the Swedes' summer houses and yachts moored outside. The Swedish police were on fearsome top form and breathalysed every driver coming off the ferry with a 'welcome to Sweden' message for each of us! A long ride to the lecture venue in the middle of Sweden with 35 Swedish equine vets in attendance to hear the full 5 hour programme of talks. There was a lot of discussion about back problems and how best to treat these, in addition to practical questions abut how to manage outbreaks of infectious diseases like flu and strangles. The local organiser did an amazing job and there was a supper for the speakers and delegates at the end of the evening's lectures. Tomorrow we are back on the bikes and off to Norway for an evening of lectures at Sandefjord.

Chronic obstructive pulmonary disease (COPD) also known as recurrent airway obstruction (RAO) or “broken wind” is a chronic condition of horses involving an allergic bronchitis characterised by wheezing, laboured breathing, coughing (usually associated with exercise or eating) and nasal discharge (especially when the head is lowered or after exercise).

The condition was known as ‘heaves’ because horses with COPD have very inflamed narrow airways and as such breathing both in and out is difficult and requires recruitment of other chest and abdominal muscles to aid with respiration, these muscles become enlarged and hence the horse develops “heave” lines.

COPD is an allergic reaction to certain otherwise innocuous substances - allergens. These allergens are typically dust, mould and fungal spores (e.g. Aspergillus). It is therefore most common in horses fed hay and bedded on straw. It is similar to asthma and farmer’s lung in humans.

Allergens enter the horse’s lungs and the horse’s hypersensitive immune system over-reacts to the “normal” pollens. The lungs become inflamed and swollen, causing the airways to become narrowed and mucus production to increase, which then leads to the signs we see in our horses.

Diagnosis is usually based on the results of a clinical exam and auscultation of the horse’s lungs. However sometimes further diagnostics are required, in which instance an endoscopic exam of your horses trachea and bronchioles can be performed and samples can be taken.

Acute flare ups can present dramatically, your horse maybe distressed with markedly elevated respiratory rate and effort, flared nostrils and sweating. If a horse is severely dyspnoeic (really struggling to breathe), the most important measure to take is to REMOVE IT FROM THE STABLE OR BARN into FRESH AIR. Keep the horse (and yourself) CALM and CALL YOUR VET IMMEDIATELY.

Treatment is all about management and minimising exposure to the allergens. When removed from the allergens the symptoms will usually subside, although they will recur if the horse is exposed to the allergens again, even short periods of re-exposure can induce acute episodes.

If it is not practical to stop stabling all together then the following changes will be of benefit:

• Minimise dust and maximise air quality in the stable.
• Soak hay or feed a low dust alternative such as haylage or bagged grass. If you are going to feed hay it should be soaked hay, you only need to soak the hay for an hour to remove the majority of pollens and allergens 60 minutes. Soaking hay for longer will reduce the carbohydrate load of the forage, good for horses and ponies that suffer from laminitis or are looking to lose weight but not necessary in managing COPD.
• Feeding from the ground allows any mucous to drain out of the lungs. Horses are designed to graze for approximately 20 hours a day, during which time the horse has its head down to the ground where mucus within the horses trachea and bronchioles can be expelled, because of this design the horse is very poor at clearing mucus from its lungs without the aid of gravity, by feeding on the floor you encourage the horse natural mucus clearing function.
• Bed on a dust free bedding. Those horses that must be stabled should be bedded on rubber matting and paper, or low-dust wood shavings. Straw contains dust, moulds and fungal spores and so is least advisable. In severe cases horse may be intolerant of any bedding in which case the mats can be washed daily. The matting has a fairly high initial cost but there is a considerable saving in bedding (and veterinary costs if your horse has RAO).
• Make sure the stable is well ventilated.
• Don't muck out or brush up while your horse is in the stable to minimise the dust in the air.

All the stables in the vicinity need to be similarly maintained or the environment will remain high risk for the horse and aim to stable your horse away from the muck heap.

Despite management changes, medication is often required, these break down into 3 broad categories:

• Bronchodilators, theses dilate (open) the bronchioles and smaller airways allowing the horse to breath more freely.
• Corticosteroids: these reduce the inflammation in the airways and damped down the immune hypersensitivity reaction.
• Anti Histamines: these damped down the immune hypersensitivity reaction that leads to the inflammation in the lungs.
• Mucolytics: these make the horse’s mucus less viscose and so easier to clear form the airways.

Care should be taken with all these drugs in competition horses, as many of them are forbidden substances under racing and FEI rules.

If the condition occurs in the summer when the horse is at pasture then it is known as summer pasture associated obstructive pulmonary disease (SPAOPD) In this case, the allergens are derived from the pasture. This is more common is summer, and management is reversed: horses should be stabled in well ventilated areas. Some horses can suffer from RAO and SPARAO which can be very difficult to manage.

RAO often limits the horses' ability to work, and it may find strenuous activity difficult. However, with prompt diagnosis and treatment the condition can be managed successfully.

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.