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Monday, 27 June 2011

Treatment for hyperphagia

My 11-year-old neutered Maltese male has developed hyperphagia. He has gained 1.4 lb (American pounds), from 9.2 to 10.6 about six weeks, and in that period of time has gone from having been very lively all his life to having a drastically reduced energy level.

More recently he has developed myoclonic jerks which seem to fit those described for Lafora's disease, though I haven't read of appetite changes and lethargy as accompanying the latter. He does seen to be somewhat more sensitive to bright sunlight, and seems somewhat "out of it."

He had a perfect checkup with normal blood and urine screening at his annual checkup in March, and has seen our vet twice since - in May, when his walking began to decrease (though his general energy level didn't seem any different), at which time his weight was normal, and last week, when the weight gain was documented. Diabetes and hypothyroidism were ruled out.

Another symptom of his current condition is that the timing of his bowel movements have changed, and though he has well formed stools, they often smell of chicken, which he has in small amounts daily in addition to his regular food - as he's been fed for most of his life.

He's scheduled for an abdominal sonogram, and I plan to request an MRI of the brain (am wondering about a lesion in the amygdala). I suppose I should wait until these results are in, but he seems to be losing ground rapidly, and would like some help if possible ASAP.

I have just found out that hyperphagia can accompany Lafora disease. Is there any treatment for hyperphagia or Lafora?

Thank you very much
Very truly ours, S. Hyman, by email

Alison Logan, vet, advises...

As an absolute number, your dog might not seem at first glance to have gained much weight. It is only when one expresses the gain as a percentage of the starting weight that this becomes apparent as a truly significant weight gain. A 1.4 pound gain for your dog is a 15% increase in bodyweight, irrespective of whether one is using American or British Imperial pounds.

Hyperphagia is not a term commonly used in the UK. Your reference to American pounds leads me to suspect you are American and it may be that the term ‘hyperphagia’ is used that side of the pond for what we would call polyphagia, or increased appetite. If I am wrong, then apologies!

There are several conditions characterised by polyphagia such as:

- Diabetes mellitus – often weight loss rather than weight gain; often overweight initially; also polyuria/polydipsia or increased urination and thirst (hence pp/pu/pd); characteristically glucose in the urine and a fasting raised blood glucose;

- Cushing’s syndrome or hyperadrenocorticism – over-production of cortisol results in pp/pu/pd and some of a range of signs such as a pot-belly, black heads and inelastic skin on the belly, crusty calcified areas of skin (calcinosis cutis), lethargy and breathlessness, bilaterally symmetrical loss of fur on the flanks without pruritus (itchiness);

- Hypothyroidism – weight gain despite normal appetite because the body’s basal metabolic rate (BMR) is lower than normal so less energy is needed from food for the normal running of the body;

- Hyperthyroidism (rare in dogs) – weight loss despite polyphagia;

- Chronic diarrhoea such that there is insufficient time for efficient digestion and absorption form the intestines as a result of, for example, Exocrine pancreatic insufficiency (or EPI), Small Intestinal Bacterial Overgrowth (SIBO) – usually weight loss in the face of an increased appetite; diagnosed by faecal analysis and a specific set of blood tests;

- Intestinal endoparasites (worms!) – again, the dog is not able to absorb all the nutrients from his food so there is weight loss despite increased appetite; faecal analysis;

- Behavioural – some dogs will quickly learn that, when they demand food, they receive food – this can be attention-seeking behaviour or a way of exerting dominance over the owner – the dog will then gain weight, just as we do if we over-ride our appetite and eat more than we actually need!

- Disorder of the appetite centre of the brain, thought to lie within the hypothalamus - a brain lesion could affect appetite control and also be responsible for other neurological signs, such as the myoclonus you mention.

At a simple, rule-out level, it would be interesting to check on the amount of food your dog is eating, and confirm that he has not found a new source of food which would explain the weight gain such as scavenging under the bird-table or nicking the cat’s food because the bowl is now somewhere that he can access. If your dog is truly polyphagic, however, meaning that his appetite is truly increased, then further investigation is certainly warranted. Diabetes mellitus has been ruled out on blood and urine tests.

The other hormonal causes of polyphagia mentioned above can be hard to pin down because hormone levels vary naturally. Urinalysis can further suggest Cushing’s if the urine is very dilute because of the very marked polyuria/polydipsia; since you do not mention that, I would assume the urine was concentrated within the normal range. It would be worth running the confirmatory tests for Cushing’s (ACTH stimulation) and a full thyroid panel.

That then brings one to Lafora disease. This is a form of epilepsy particularly found in miniature wire-haired dachshund, bassett hound and beagle but also at a lower level in other breeds. The age of onset tends to be from middle-age onwards, progressing slowly so that life expectation may be much as would otherwise be expected. Management of an affected dog is very much by avoiding known triggers. As you mention, bright or flashing lights are a common trigger so wearing doggles and not having a television switched on when an affected dog is in the room can help, for example. Sudden movements can also be a trigger.

There is a DNA test available for miniature wire-haired dachshunds for Lafora disease, performed on a cheek swab.

This is an interesting question with much to consider. Your dog is lined up for further investigation so I hope that a definitive diagnosis is reached, hopefully with curative treatment.

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