Animal Care

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KING OF THE TILL

Mark Newton-Clarke, MAVetMB PhD MRCVS, Newton Clarke Veterinary Surgeon

So, last Sunday, I called into the surgery at Swan House to look after the practice cat, BJ (stands for Blue Juice...don’t ask), as I do every weekend. Instead of his usual vocal and tactile greeting, poor BJ couldn’t even raise his head from the pillow and had eaten nothing overnight. What’s more, there was quite a mess in his litter tray...and the bath. Grateful for small mercies, I did a clean-up but was far more concerned about his medical condition. Vomiting and diarrhoea are not uncommon symptoms in middle aged and older cats (though far more so in dogs) but as decomposing organic ‘stuff’ is not attractive to most cats, the cause of BJ’s problems was not likely to be scavenging rotten food. Instead, a form of inflammatory bowel disease (IBD) was much more likely, although there are plenty of other things that can cause similar symptoms. However, BJ has a history of similar problems and so this seemed the most likely.

Although you might think a cat living in a veterinary practice for the last 16 years or so would have learned some manners – the opposite is true for BJ. Consequently, he was and is almost impossible to examine even with the expert help of a veterinary nurse, which I did not have on that Sunday morning. A cursory examination therefore followed, happily without serious injury (to me, that is) and so, taking a deep breath, I injected a mixture of steroids under BJ’s skin. The injection contained dexamethasone, a drug that may be familiar to you as it has been employed as a treatment for human cases with serious Covid-19 infections.

After making sure some freshly cooked chicken was available, I left BJ to rest and gave him two litter trays, just to be sure. Later on in the day, I called in to see how he was doing and was met by a very different cat, all the food eaten and BJ looking much more like his normal bitey self. Since then, no further diarrhoea and everyone’s much happier.

So, how can a drug used to treat a form of IBD in cats be useful in severe Covid-19 cases in humans? The answer lies in the powerful anti-inflammatory activity of the steroids, a family of molecules derived from cholesterol that have been found in even the simplest of animals and many plants. As happens so often in nature, a basic atomic structure is modified to produce a wide diversity of function. Many of us think cholesterol is ‘bad’ even though it forms an essential structural part of every cell in our bodies and in different forms acts to control growth, sexual cycles, kidney function and cellular metabolism. This is one flexible friend! The story of how steroids have been researched and developed into the therapies we use today is quite interesting and it all started during the Second World War. American intelligence learned that Germany had discovered a way of producing steroid hormones that could protect their pilots from altitude sickness. As a consequence, a huge impetus was given to research in the United States into the manufacture of steroids, necessary as their production from animal and plant sources was difficult and very expensive.

With none of our 21st Century technology, scientists in the 1950s somehow discovered that a species of yam contained a cholesterol-like substance that could be used as the starting point for the chemical manufacture of biologically active steroids. Determining the precise structure of any molecule seems simple these days but, back then, the structure of DNA had only just been discovered, through the tortuous process of making a crystalline form and shining X-rays through it. The pattern of scattered X-rays is dependent on the atoms present and their relative positions; this technique is called X-ray crystallography, unsurprisingly! So, the organic chemists made different compounds and the boffins analysed what had been made. These compounds were then tested on mice to see which had biological activity and breakthroughs in the treatment of leukaemia and arthritis were made.

At some point, a fluorine atom found its way into one of the newly-made steroids and when tested, this modification was found to increase the antiinflammatory activity by ten-fold. This is the drug we now know as dexamethasone and its use is not confined to cats and Covid. However, the anti-inflammatory steroids (known as corticosteroids, as they are made by the adrenal cortex) come with ‘issues’. Taking them for a long time, at high doses, causes a suppression of the patient’s own production, making them dependent on the drug. What’s more, the corticosteroids affect renal function, fat production and cause muscle loss. Not sounding so rosy, now, eh? However, we now use the most natural form of the synthetic steroids, called prednisolone, at the lowest effective dose and, if possible, only every other day. In this way, side-effects are minimised and benefits maximised, restoring quality of life as much as possible.

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HOT AND BOTHERED

Keith Jones BVSc MRCVS, The Kingston Veterinary Group

At long last… the weather seems to be looking brighter and, hopefully, muddy paddocks are slowly becoming a distant memory. But there’s always something to think about throughout the year where horses are concerned. Here we look at how to care for your horse in the summer and things to consider at this time of year.

With the sudden change in weather, it is important to make sure your horse always has access to clean water and that their intake is monitored, as the heat will also dry out the grass and this may lead to colic. Monitor your horse’s weight weekly, using a weigh tape, and adjust their feeding/turnout time accordingly. With warmer weather comes the pesky flies. Flies can carry disease and an allergic reaction can result from any fly bite; all flies can cause irritation and annoyance to both horse and the rider and so it is an important thing to consider when working or competing your horse. Although there are lots of breeds of flies, there are a few in particular that are upsetting for horses.

Horse flies are particularly troubling for horses. They are most active on warm, sultry days and especially around woodlands. They are often quite large and their nasty bite leaves painful papules (pimples) and wheals (small lumps) that are irritating to both the horse and the rider. Horse flies rarely enter dark places, so offering your horse stabling can offer some protection.

Black flies are smaller in size and breed near rapidly moving water. Black flies commonly feed around the face and particularly in the ears where they trigger allergic skin reactions and are mostly active at dawn and dusk. Bites form as painful lumps often with pin prick areas of bleeding or crusting.

Midges are just 1mm-3mm long and hover in swarms at dawn and dusk. They are mostly seen around stagnant

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water areas or ponds, so avoid these areas if possible. Different types of midges feed on different sites of the body. A common feeding site is the mane and tail and can be a factor to the cause of sweet itch.

Sweet itch in horses, also known as pruritis, describes the unpleasant sensation that leads horses to bite, scratch or rub at their skin. This can sometimes be so strong that horses will cause severe damage to themselves or their environment. Pruritus is known to result from the stimulation of special nerve endings and receptors in the skin. The three main factors to induce the itchy skin is ectoparasites (biting lice), infections and allergies. It is vital that the treatment targets the cause of the pruritus and relieves the itch itself.

Preventative measures to reduce bites; use antimidge/fly turnout rugs and masks, apply a long-lasting fly repellent (spot test first to test for sensitivity), spray the stable with insecticide, eliminate areas of still water where midges might breed. Practise good hygiene around the yard, worm your horse against bot flies in the winter and stable your horse when the flies are bad.

Sun damage can be underestimated in our country, and worryingly it can be just as harmful to animals as it is to humans. The pigmentation in hair and skin protects against the penetration of ultraviolet light, so any non-pigmented horse or a horse with white–skinned areas is prone to sunburn damage. The horse’s face and heels are commonly affected areas. Ensuring fields have shady areas is essential, although it sometimes prove difficult to make sure your horse grazes in this area. There are equine sun barrier creams available; another option is to use a head and muzzle mask to provide some protection. If you have a horse that is prone to sun-burn it is advised to stable the horse at high-risk times.

Worms also complete their life cycle more quickly during the warmer weather. It is now recommended that a horse’s worm burden should be monitored every 6-8 weeks through the grazing season and only wormed if appropriate.