Monday, June 1, 2015

How do I know if my pet has "dementia", or cognitive dysfunction syndrome?

Senior pets like Phil are vulnerable to cognitive dysfunction syndrome. (This is him drying himself off after a bath).
Do you live with a senior dog? I don’t like admitting it (to myself), but Phil is a senior. How senior I know not precisely – he is a rescue dog. I like to tell myself he is four years old, but we met seven years ago, when he was fully grown and had had time to develop florid periodontal disease (which, granted, doesn’t take too long for a microdog), so that's more than a smidge unlikely.

In practice I see a lot of senior pets and suspect that a percentage of these have cognitive dysfunction syndrome (aka doggy dementia). I say suspect because this is a rule-out diagnosis – it’s not possible to make a definitive diagnosis ante-mortem, although we can have a good idea.

Thus I was particularly interested in attending Dr MeghanHerron’s talk on cognitive dysfunction syndrome at the AVA/NZVA Pan PacificVeterinary Conference last week.

Dr Herron discussed changes that occur in all aging animals – sensory decline (usually a degree of hearing and vision loss, though it’s hard to know if olfactory and taste sensation is affected she thinks it is to some degree), musculoskeletal changes (osteoarthritis being the main issue), and behaviour changes (sleeping more would be a biggy).

Cognitive dysfunction syndrome (CDS) is not inevitable in older pets, though she cited a study by the Animal Behaviour Clinic at California University which found that 28% of dogs 11-12 years old and 68% of dogs 15-16 had signs of cognitive impairment. Onset was a tad later in cats: a study by Moffat and Landsberg found 28% of cats 11-14 and >50% of cats over 15 had signs of cognitive impairment.

So how do you know your companion has CDS? Dr Herron uses the acronym DISHA to make a clinical diagnosis:
  • D is for disorientation, which manifests as changes in spatial awareness, inability to find their way around the house, wandering aimlessly.
  • I is for interaction changes, which often means decreased interaction, but some pets get clingier (I hear this a lot from cat owners, although in fairness most of these uber-clingy cats turn out to have raging hyperthyroidism and they cling to their owners in the hope that the owners will feed them constantly because they have a hyperT4-enhanced appetite)
  • S is for sleep/wake cycle changes. Sure, they might sleep a lot – but they might also wake in the night, wander around, and be restless.
  • H is for house-soiling, which might mean peeing inside, or not alerting you when they need to go out, or incontinence.
  • A is for activity level changes – which can be decreased exploration, decreased excitement, under-grooming etc. OR it can go in the other direction – increased agitation, more restlessness etc.

For me this is a neat way to summarise the behaviour changes we see (and reassuring when it comes to Phil!). Dr Herron also gets clients to fill out the Senior Pet Screening Checklist and the Cognitive Dysfunction Screening Checklist (found in the Handbook of Behaviour Problems of theDog and Cat).

She stressed that CDS is a rule-out diagnosis. Remember that senior and geriatric patients often have co-morbidities and even if they do have CDS the signs might be improved by managing the signs of concurrent disease. The most common co-morbidities I see in older pets would be renal failure, diabetes, Cushing’s syndrome (aka hyperadrenocorticism), hyperthyroidism, osteoarthritis, screaming periodontal disease (it’s amazing the difference a dental can make, removing a huge nidus of infection and taking pain away).

But there are also behavioural differentials to consider, and this can be tricky as there can be a lot of overlap between signs. Dr Herron listed generalised anxiety, separation anxiety, fear-aggression, pain-aggression, phobias, lack of house-training and compulsive disorders among her behaviour differentials.

CDS is not a curable condition, but Dr Herron stressed it is manageable. That is, the impact of signs can be reduced to improve the animal’s quality of life. She discussed environmental enrichment, dietary changes, nutraceuticals and drugs that have been shown to delay progression of CDS. Her message is to use what works. If something does work you will normally have to continue treatment with that something for the remainder of the animal’s life, unless there’s a medical reason not to.

Dr Herron mentioned a few drugs and supplements that aren’t available in Australia yet but ultimately it was a very positive talk. She was a brilliant speaker who has oodles of clinical experience which really shone through.


Herron, ME (2015) Cognitive dysfunction and behaviour changes in the aging pet. Proceedings of the AVA/NZVA Pan Pacific Veterinary Conference. AVA, Sydney.