Browsing tag: Cushing’s disease

Ask a Vet Online – ‘My vet says my poodle cross Pom, may have cushings disease what is this please?’

Question from Carol Fogerty

Hi my vet says my poodle cross Pom ,may have cushings disease whot is this please

Answer from Shanika Winters MRCVS, Online Vet

Hi Carol and thank you for asking about Cushing’s disease (HAC hyperadrenocorticism) which is a condition where the body makes too much of the steroid cortisol which can result in a variety of symptoms.  HAC is most common in middle aged to older dogs but does also affect cats, horses, hamsters and ferrets.

There are three different types of HAC:

Pituitary dependant HAC (PDHAC) is the most common type and this is when a tumour of  the pituitary gland in the brain is making too much of a hormone called adrenocotricotrophic hormone (ACTH)  this causes the adrenal glands to make too much cortisol.

Adrenal dependant HAC (ADHAC) is less common, this is when a tumour of the adrenal glands causes too much cortisol to be produced.

Iatrogenic HAC (IHAC) is when very high doses of steroid given as medication lead to symptoms of HAC.

What are the signs of HAC?

If your pet is showing some of the following signs then your vet may suspect HAC:

Increased drinking (PD polydypsia), increased urinating (PU polyuria), increased appetite (PP polyphagia), a large rounded low slung abdomen ( tummy), muscle weakness, hair loss on both sides (bilateral symmetrical alopecia), hard areas under the skin due to deposits of the mineral calcium (calcinosis cutis) and dark spots on the skin due to blocked keratin (hair protein) filled hair follicles  (comedones).

How do we test for HAC?

There are several blood tests, urine tests and diagnostic imaging tests than can be done to try and make a diagnosis of HAC:

    Routine blood tests in cases of HAC may show up increased levels of liver enzymes, increased cholesterol, increased blood glucose (blood sugar) and also changes to the white blood cell numbers.
    Routine urine tests may show an increase in glucose, white blood cells and protein.

More specific tests for HAC include:

    Urine creatinine: cortisol ratio, here a urine sample collected from your pet is sent to a laboratory for analysis, abnormal results are found in cases of HAC but can also suggest diabetes, liver disease or womb infection (pyometra).
    ACTH stimulation test, this is a set of blood tests in which a blood sample is taken from your pet, an injection of artificial ACTH is given into a vein (blood vessel) and 1-2 hours later another blood sample is collected. The laboratory results are abnormal in approximately 80% of dogs with HAC, this test is also often used to monitor dogs on treatment for HAC.
    Plasma cortisol level, this is a blood test which directly measure the level of cortisol in the blood , the blood sample has to be treated very carefully and sent to the lab quickly so as to get an accurate result.
    Ultrasound scan of the abdomen can be used to check the size of the adrenal glands (found next to the kidneys), look for a tumour and assess the other abdominal organs. IN PDHAC the adrenal glands are usually normal size or slightly enlarged with ADHAC the adrenal glands are usually different sizes, the large irregular gland being the one with the tumour.
    Low and High dose dexamethasone suppression test (LDDST & HDDST) are blood tests where the effect of artificial steroid on the adrenal glands is measured, the results can sometimes help tell apart PDHAC form ADHAC.
    Magnetic resonance imaging (MRI) scans and computed tomography (CT) scans can be performed at referral centres to help in the diagnosis of HAC and also tell which type it is.

How is HAC treated?

Trilostane is a tablet with blocks a step in the production of cortisol in your pet’s adrenal glands therefore decreasing the amount of cortisol in your pet’s body.

Mitotane is another tablet which works by destroying the parts of the adrenal glands that produce cortisol.

Surgery to remove the actual tumours can be performed usually at referral centres.

Trilostane and mitotane are the most commonly used treatments for HAC, they are effective on both PDHAC and ADHAC and your pet should have regular blood tests to monitor that the dose given is correct for your pet. Too much medication for HAC can lead to symptoms of Addison’s disease (Hypoadrenocorticism) where there is not enough cortisol which includes dehydration, depression, diarrhoea and lethargy (weakness).

I hope that my answer has given you some useful information about HAC, the exact test done on your pet will need to be discussed with your vet. The aim of treating your pet is to reduce the signs of HAC to improve your pet’s quality of life and is best achieved by working closely with your vet.

Shanika Winters MRCVS (online vet)

Rain Scald, Mud Fever and Greasy Heels – Wet Weather Care for Horses

I heard on the news recently that last year was one of the wettest on record. I don’t know if it’s true – but it certainly feels about right! The big danger to our horses from this, of course, is Rain Scald and Mud Fever.

Most people have probably come across Rain Scald on occasions – the scabs hidden away in the coat feel like mud, until you pull them up and see the characteristic “paint brush” appearance as the hair stays stuck in the scab. Rain Scald is caused by a bacterium called Dermatophilus congolensis. This usually lives (fairly) harmlessly on the skin, but if the skin gets and stays wet, the bacteria can invade and set up an infection.

Most cases are mild, with just a few scabs here and there, but (especially in older horses and those with Cushing’s disease) it can be more general and leave large raw patches. Even a mild case can put a horse “off games” if the scabs or raw patches are under the saddle.

Most cases resolve on their own with simple care – gently brush out the scabs, and most importantly keep the area dry to allow it to heal. That said, older horses and those with other diseases may need a helping hand, in which case a short course of antibiotics from your vet will usually clear it up. HOWEVER… Unless the underlying problem is sorted, it will rapidly return! Prevention is far more important, and that means keeping the skin as dry as possible. Remember, if your horse gets wet, that’s fine as long as he can then dry out thoroughly. It’s if the skin stays constantly wet that problems ensue – and watch out for rugs, especially in early autumn! When it’s wet, but not that cold, horses can easily sweat up under their rugs, and sweat seems to be even worse than rain for causing Rain Scald.

The other thing to watch out for, of course, is Mud Fever. This is an infection of the skin behind the heels (its sometimes called Greasy Heels), and is most common in horses with long feathers. It’s a far more complicated disease than rain scald, and has a large number of contributary causes. The most important is wet weather, of course – as the skin gets wet, bacteria can invade, as in rain scald – long feathers keep the water trapped in the area, slowing down the drying, so cobs and heavy horses are more prone. However, mites are also a known cause (the first signs are usually stamping of the hind legs), and its not just bacteria, because some cases include yeasts and other fungi as well. Sometimes, really aggressive bacteria like Pseudomonas can establish themselves, and they can be really difficult to manage.

The symptoms vary, but generally it first presents as scabs in the angle of the heels behind the pastern. If untreated, or as the infection gets worse, cracks in the skin can open up and start oozing fluid and pus, and the legs thicken. Eventually, lymphangitis can occur and ultimately, the skin can slough or even become gangrenous.

Initial treatment is very simple: wash the affected area with a skin disinfectant (like Hibiscrub or similar), and once the scabs are softened, gently wash them off. This may take several days of work! If the infection progresses, or doesn’t improve, you will need veterinary attention.

Most cases respond well to a course of first-line antibiotics (e.g. Penicillin/Streptomycin or Timethoprim Sulpha); however, if it doesn’t respond in a week or so, I would always take a swab for bacterial culture and sensitivity testing. This give you a much better idea what bacteria you’re dealing with, and how best to kill them – I had a case once which turned out to be a multi-resistant Pseudomonas infection, that needed some really powerful off-license antibiotics to resolve it. Sometimes you can use topical antibiotics (creams, ointments etc), and in severe cases, I have occasionally used a “bespoke” ointment that I made up from several different antibiotics and an anti-inflammatory. If there are mites involved, most vets will use an injectable anti-mite drug; however, this isn’t licensed for use in horses so has to be put up by your vet.

As usual, prevention is much better (and cheaper!) than treatment, though, so keeping the heels dry is vital. Sometimes using an aqueous cream like zinc and castor oil, or Vaseline, can be useful in encouraging the water to run off – but if you do use them, make sure you wash it off and dry it thoroughly once or twice a week before reapplying, so it doesn’t get too thick.

Of course, in an ideal world, keep the horses out of muddy fields and trackways… But given the recent weather, I fear we’re all going to have to be a lot more careful to keep our horses and ponies warm and dry this autumn.

If you are worried about any symptoms your Horse or pony may be displaying please talk to your vet or try our Interactive Equine Symptom Guide to help decide what to do next.

Looking after the Older Horse

When I was training as a vet, a 20 year old horse was considered really quite old. Now, however, I regularly find myself working with healthy horses in their late twenties and thirties – even a few that go on into their forties!

That said, horses don’t age uniformly – one may be sprightly and fit at 30, while her paddock mate is really feeling his age at 20, so there’s a lot of variation. The challenge is maintaining them at the best quality of life for as long as possible.

To do so, we need to consider three things:

• Work and exercise
• Preventative health (worming, dental care etc)
• Disease management and medication

I’ll deal with these in sequence, although really they are of course all interconnected.

Work and Exercise

PerryI’d like to introduce Perry, a horse I’ve known for many, many years. Born in 1986, by 2002 Perry was a successful Eventer, competing on the Affiliated circuit, and usually well up in the places. However, by then he was starting to slow up a bit, and his then-owner decided it was time to reduce his workload. He was struggling in particular with the dressage and show jumping, so they sold him on to a friend of mine as a Pony Club horse for Tetrathlon. All he had to do was carry his (fairly novice) rider round a cross country course – the phase he enjoyed the most anyway. Relieved of the need to work in an outline, or in collection, he flourished at Tetrathlon, going on to compete at the National Championships.
Of course, in time, his low-grade arthritis (which I’ll talk about more later) meant that he was struggling with the cross country requirements, and he moved into a semi-retirement as a hack. He’d seen it all, done it all, and was as close to 100% in traffic, tractors and low flying aircraft as any horse could be.
For most horses, as long as they can work, they want to – generally (and there are always exceptions!), it isn’t in a horse’s best interests to take him out of work one day and retire him to a field. A gradual wind-down over several years is kinder, and helps to keep him interested and alert.
So, by changing career, Perry had an extra five years of competition, and then many more years of useful work – simply because his various owners were wise enough not to over face him, but to play to his strengths.

Preventative Health

I’ve talked before about the importance of regular dental work – in the older horse, it is doubly important. As the horse ages, his teeth undergo a number of changes. Although it appears that teeth grow constantly, that is in fact an illusion – the adult teeth are pretty much a fixed length, but most of the tooth is hidden away within the gums (the reserve crown). As the tooth is worn down by chewing, more of this reserve is extruded (which is, by the way, the basis of ageing horses by dentition). However, sooner or later, this reserve is expended, and the teeth “cup out”, becoming small, loosely held, concave structures, of limited use for chewing. Good, regular dental care can help delay the onset, and can help the horse to manage as the teeth cup out. Remember, as long as there are a few pairs of teeth in occlusion (i.e. Facing each other), the horse can still chew, he’ll just be very slow about it! In my experience, teeth generally start to cup out about 30-35 years of age, but it depends on their dental history – more use and wear and tear means the teeth are ground down faster.
Worming is also inceasingly important in the older horse, simply because although they may have higher immunity to worms (this is still debated, but does seem likely), they also have less reserves to cope if they have a heavy infestation. The spring is a particularly risky time, as sometimes large numbers of small redworms can emerge all at once, causing massive gut wall damage. It is important to make sure that at some point over the winter, you use a wormer that is active against hibernating (hypobiotic) worm larvae – currently, the only wormers on the market that have this activity are a full 5 day course of Panacur, and (reportedly) Equest.

Foot care is always important, as older horses can suffer some terrible hoof capsule problems if left untreated.

I always recommend that people keep up vaccinating their horses, even if they’re not competing or going out. Equine influenza probably isn’t essential in a stay-at-home horse or pony (although they can still contract it if they’re in contact with a younger friend who does go out and do), but Tetanus vaccination is essential. Just because a horse is old doesn’t mean you can stop vaccinating, because tetanus kills horses of any age just as easily. It’s also a really useful opportunity to have a general “MOT” and get your vet to check the horse over thoroughly, to detect and problems before they become too serious.

Disease Management

Although many horses lead a long and healthy life, the probability is that as they enter old age, they will suffer from one or more “chronic diseases”. These are generally low-level conditions, and in the older horse are usually manageable rather than curable. Probably the most common are arthritis and Cushing’s disease, but malabsorbtion diseases and some tumours aren’t that uncommon either.

The key factor is managing the disease in such a way that the horse doesn’t suffer from the symptoms, and is able to keep up as much work as possible, for as long as possible.

Arthritis is perhaps the commonest condition of older horses, and those that aren’t so old. In most cases, it is due to simple wear and tear on the joint surfaces. The harder a horse has worked, the more rapid the onset of arthritic changes. It’s often the case that, initially, a horse will have trouble working in an outline, and perhaps with show jumps, but hacking and cross country, with it’s more open jumping style, is less of a problem. This of course was exactly the case with Perry. Managing arthritis is a lot more than just monitoring exercise, however – nowadays, we no longer need to just accept “a bit of stiffness” in the older horse. It’s often best to use several different strategies. I generally recommend a combination of joint supplementation (feed supplements such as Cosequin and Newmarket Joint Supplement are the most popular, while injectables like Adequan are more expensive but possibly more effective) with analgesics (bute and/or Danilon, usually) as required. Although painkillers like bute don’t address the underlying disease, they reduce the inflammation and associated pain. Although there can be side effects, it really isn’t fair to put a horse through the pain and discomfort of arthritis without some pain relief; if side effects are a particular concern, Danilon has a much lower risk, although it seems to be a little less effective. Its usually best to start out using bute only as required, and then build up the dose as necessary. Perry, for example, started using bute about 10 years ago, but just a sachet or so immediately after a competition. As he’s got older, he uses more, and at the moment he’s on an average of 4-5 sachets a week – enough to keep him comfortable (and galloping round his paddock like a yearling!).

Cushing’s disease (hyperadrenocorticism) is most common in older horses, and is caused by a micro-tumour in the pituitary gland. This results in an excess of circulating cortisol (a stress hormone), that causes the characteristic symptoms of abnormal fat pads (typically over the eyes and as saddle-packs), excessive drinking and urination, and increasing susceptibility to minor infections and laminitis. Ironically, the “classic” shaggy coat of the Cushingoid horse isn’t entirely due to cortisol – the presence of a tumour in the pituitary causes a malfunction in the part of the brain that controls body temperature, causing retention of a winter coat for longer. Cushing’s isn’t curable in horses, but symptoms can be partially controlled by management (regular clipping, diet and exercise control and remedial shoeing), or largely eliminated with some medications – Cyproheptadine (Periactin) may be of some use; however, Pergolide (Prascend) is highly effective, and is licensed for the treatment of Cushing’s.

Gut problems of one sort or another are also more common in older horses – these may be malabsorbtion issues, caused by thickening of the gut wall, or an increased susceptibility to colic. This may be due to a diffuse Lymphoma (a cancer of the white blood cells) which is the commonest tumour of older horses. In these cases, the key is to feed a highly digestible, high feed value ration, possibly with a probiotic to enhance digestion.

Tooth loss is also a problem in the older horse – as I discussed earlier, eventually the teeth “cup out”, at which point there’s little more that can be done, dentally. The next phase is that the tooth falls out, leaving naked gums. I remember once doing a regular tooth rasping on a 38 year old mare – I put a hand in to have a feel around, and four teeth fell out in my palm… (she actually did better once the teeth were out than she had in months!). An edentulous (toothless) horse needs a soft, ultra-high fibre diet; typically a mash made from fibre pellets or pencils. Horses can live healthily for quite some time on such a diet – however, once your horse has reached this stage, it is probably time to consider how long you can fairly keep him going.

If you can stay on top of all these points, you have every chance of keeping your older horse going for a long, healthy life – as Perry has had, and indeed continues to have.

If you are worried about any symptoms your horse or pony is showing, please talk to your vet or check how urgent the problem may be by using our Interactive Equine Symptom Guide written by expert equine vets.

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