30/03/2024
Easter, Spring, and Asthmatic horses
Today, finally, things have started to look like Spring is arriving, and with Spring comes the changing priorities for how we manage our horses. Now that the driving rain has eased enough for us to raise our heads and take a look there are new leaves forming on the trees as well as blackthorn blossom and catkins on the willows. Catkins always mean airborne pollen, and for some horses airborne pollen means asthma.
Where we are, here in Midhurst, there were some long yellow hazel catkins to be seen in the hedges a month ago, but today there are willow catkins out all around us. Usually the weeping willows are among the first trees to come into leaf and the last to lose their leaves in Autumn. But there are many willows, and a lot of them like the Goat willow and the White and Grey willows are easily overlooked as they are often scrub and a bit shapeless, and as such are hidden in plain sight.
I have noticed over this last week a little flurry of asthmatic horses. Two of whom have had no history of asthma before although they are both older patients and as such are in a higher risk group for developing asthma. My daughter’s mare and another horse on the same yard as her are also asthmatic, and as such I keep an eye on the trees around them throughout the year. In general, neither of them suffer breathing troubles in the winter. And although there are many oak and some poplar trees around them I suspect that it is the willows which really set them off. On examining the horses this morning they are just starting to breathe a little faster, and a little more laboured while at rest. And on squelching across the field there are indeed willow catkins starting to appear in the hedge.
Summer pollen-associated asthma in horses is difficult to manage as the pollen is everywhere in the air. In the UK the native trees which are anemophilous, that is wind pollinated, are the Oaks, the Birches, the Hazels, the Alders, the Willows and the Poplars. They can easily pollenate between trees a kilometer apart and often further just by the amount of pollen in the air, so there is nowhere to hide. Also as with human hay fever, which is also an allergy to pollen, atmospheric conditions play a significant role in the degree of horse's exposure to airborne pollens each day. And patients may also be allergic to several different tree pollens as well as grasses and pollen from other anemophilous plants too. Some horses’ reactions to pollens are very distressing and in human terms would be termed as very severe attacks. For horses who suffer like this, inhaled steroids are the only really effective treatment apart from moving to somewhere free of the pollen or pollens which trigger the attacks. Unfortunately, inhaled steroids come with a price tag, whether that is with human type single-use asthma inhalers or the excellent veterinary ones which are now available. The best investment is probably to buy a Flexineb nebuliser. These recharge on a USB charger and use relatively cheap steroid which we can supply to clients. However they cost the best part of £1000 on-line although we may be able to better this price a little for patients. If you are thinking of buying one second-hand there are a couple of things to watch. One is that they come in three sizes and you need the correct fit for your horse. Also the heating element needs replacing every couple of years and it may be cheaper to buy it new all things considered.
It is in the nature of allergies to worsen over time, and an uncontrolled allergy may progress sooner than a controlled one does, as well as causing distress for the patient. Pollen-related asthma patients will always have an unexpected severe attack sooner or later, usually on a bank holiday or the day before you go on holiday. So it makes sense to have some inhaled steroid therapy to hand for your horse even if you do not need it on a day-to-day basis. Steroid tablets are a possibility for emergency use or where there is no other choice but there is a theoretical risk of laminitis and side effects with prolonged use. Other drugs like clenbuterol syrup or powder in the feed are useful but they are not enough to combat significant ongoing asthma or a severe asthma attack, and as such you do always need to have a steroid treatment to hand.
I would be very interested to see any comments from owners who have just started to see asthma again after a winter remission, and to know what if anything is bearing catkins within a kilometer or so of their horse. Look up Hazel, Alder, Birch, Oak, Poplar, and the several native Willow catkins so you can identify them and then see what you can find. Getting a handle on what sets our horses off reduces our own stress, as it stops it all being so frustratingly unpredictable and random. And it also allows us to plan ahead with effective strategies and treatments.
Below are two photographs of a Grey willow (I think!) seen on this morning’s dog walk, and two of the White willow behind my daughter’s horse’s stable, growing alongside a golden variant of the White willow.
Happy Easter to all.
John.
