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Gems of wisdom and thinking

by
01 December 2010, at 12:00am

LIBBY SHERIDAN brushes up on FLUTD, itchy dogs and diabetes – at the London Vet Show

WE can sometimes think that we are pretty much up to date on a clinical subject and steer away from CPD in certain fields, feeling we will gain more from attending lectures where we have recognised gaps in our knowledge.

But taking this approach can mean that we sometimes miss out on some real gems of wisdom and thinking and opinion can change markedly in even a few years.

Stressed cats

One such personal example came from Professor Danielle Gunn-Moore’s lecture at the London Vet Show: “Feline lower urinary tract disease in the 21st century – what we know now and didn’t know then”. 

Prof. Gunn- Moore’s whistle-stop tour through the condition covered clinical signs, causes, diagnosis and treatment and highlighted how much more we have discovered about the condition in the last 10 years. 

The disease is seen most in young- to middle-aged, neutered, over-weight cats, with restricted access to outside and eating a dry diet. The most common form of FLUTD, feline idiopathic cystitis (FIC), seems to directly relate to stress and an alteration in the affected cat’s nervous system and inputs to and from the bladder.

As previously recognised, these cats will often be living in a multi-cat household and it is interesting to note that the cat’s stress level may not be directly proportional to the number of cats in the house per se, but rather how many groups of cats there are (a group being identified by observing its members sleeping together, grooming each other and sharing resources such as food, water, litter trays, resting and hiding places).

In managing these cases, the owner will need one set of resources per group, rather than per cat (unless, of course, each group consists of just one cat).

The cat’s individual response to stress is determined in part by genetics and part environment. The phrase, which seems to be increasingly applicable to many diseases these days, is that clinical disease results when there is a combination of a “sensitive individual in a provocative environment”.

Cats which develop FIC tend to respond differently to stress and show exaggerated arousal. Their experiences in utero and during kittenhood may also be important. Often they will be living in a chronically stressful environment and one to which they have been unable to adapt – classically living with another cat they don’t like.

These cats lack cortisol and are unable to cope in the normal way (interestingly, black and white cats appear predisposed, but gingers remain nonchalant!). Rather than hiss or show typical fight or flight responses, they show displacement activities when stressed and often stereotypical behaviour, such as increased eating, drinking, grooming or urination. Some may just freeze. But owners of susceptible cats may be able to spot impending FIC episodes by observing early stereotypical changes in their cat’s behaviour. Excessive grooming of their tummy – often attributed to fleas – may in these cats be an early marker of pain, becoming evident before haematuria or dysuria is seen.

Stretched pockets

Looking at a commonly discussed subject from a different perspective also allows insights to surface. Anke Hendrick’s lecture, “The chronically itchy dog owned by the financially challenged client – what are the options?”, hit to the heart of a very common dilemma in practice.

In this era of financial austerity, how can we ensure that we don’t sacrifice good clinical practice? Anke gave some clear advice to help avoid costly inappropriate investigations and highlighted where cost savings could be made in the treatment of certain conditions.

She made the point very clearly early on that to successfully treat the chronically itchy patient, a diagnosis should always be sought. This doesn’t always need to involve lengthy trial treatment or a myriad of expensive blood tests or biopsies.

Rather, she recommended stepping back and carefully prioritising the differential diagnoses and giving thought to what is most likely in this particular case. Take into account the pattern, change and progression of the pruritus and response to previous treatment, along with assessment of the lesion type and its distribution. 

Common things are common; most pruritic skin disease will be the result of superficial inflammatory disease, with ectoparasitic disease, microbial infections or overgrowth, and hypersensitivity disorders (namely flea bite hypersensitivity, atopic dermatitis and dietary hypersensitivity) seen most commonly.

Don’t forget, however, that a combination of causal factors is frequently seen, and if you find one factor, don’t stop there. It’s important to rule out or control any parasitic disease and/or microbial infection early on, as these make assessment of any other underlying disease more difficult.

For parasitic disease, using the very effective products we have available to us is a wiser use of the owner’s money than using cheaper, less effective products.

For microbial disease, where money is a concern, there is no evidence to show that a superficial pyoderma will respond any better to a combination of systemic and topical treatment than to systemic treatment alone.

Once under control, if there is a risk of recurrence, following up systemic treatment immediately with a topical on-going treatment may help to limit costly flare-ups.

She discussed the hypothesis of “summation of effects” (where different pruritogenic stimuli can add together to give an overall level of pruritus) and the concept of the pruritic threshold (where an individual only starts to show pruritus once its own threshold has been reached).

Taking one or two factors out of the equation can mean that an individual might drop below its pruritic threshold and you may not have to treat or address every problem. For example, a dog with atopic dermatitis compounded by a staphylococcal or malassezia overgrowth might not need any treatment once these secondary pruritic factors have been brought under control. 

Looking deeper

David Church’s lecture on “The complicated diabetic – what are the options?” was a goldmine of useful information and tips on managing these often frustrating cases and he highlighted common factors causing difficulties with diabetic control.

He categorised these complicated diabetics into two situations: one where the insulin appeared not to work, and a second where the animals were presenting with inappetance, vomiting and depression and were severely unwell as a result of their diabetes (most commonly ketoacidosis).

A typical scenario of the former situation was where, despite increasing insulin doses, there was a minimal response and persistent hyperglycaemia. Typically this is the result of insulin resistance caused by concurrent disease which he categorised into non- endocrine (for example, renal failure, urinary tract infections or heart disease) and endocrine disorders. If a dog has both diabetes mellitus and hyperadrenocorticism, the latter will manifest itself through lack of response to insulin (where the cortisol interferes with insulin action) long before typical cushingoid signs are seen.

Acromegaly in cats is also now thought to be much more common than previously thought, with the RVC diagnosing the condition in about 25- 30% of the diabetic cats tested there. The classical presentation of the fat- headed cat with the thick tongue presents in less than 10% of cases and most will look like normal cats. Typically they will be difficult to manage diabetics who are passionately hungry.

Knowing about any concurrent disease allows us to suggest treatment, of course, which may or may not work in all cases (radiotherapy treatment for acromegaly improves the diabetic control in about 80% of cases), but more importantly it helps us to manage the client’s expectations, which these days may be just as important as anything we do clinically.