The blind Pom pup I took in was seen by an eye specialist today and he was diagnosed with Microphthalmia. In 13 years rescue and nearly 30 years of dog ownership I never came across it. Is there a test for it (parents)? How common is it? Anyone?

I have booked him in for an OP to have the tiny non-functional eyes removed and the lids stitched shut as they already start to roll in due to lack of proper sized eyeball.. Poor fella..

Never heard of it in dogs, but in humans (although not common) is often syndromic, with several other organs/systems involved.  As for genetics, there are so many causes it'd be impossible to list... and I think in terms of development, the causes can be varied.  So as it's not a discrete 'defect', rather a description of what has happened during development (for unknown reasons), I would think finding the responsible gene and carrier testing would be unlikely.  Unless of course, it is more common in Poms than you could expect by chance. I may be talking utter rubbish though - I can tell you about ophthalmic genetics in humans, but it's just speculation for dogs!
Hope the little chap's op goes well!
Clare

Thank you for your reply! The eye specialist mentioned that it was genetic in dogs and that she has seen an upsurge of it in toy breeds over the past 10 years? I've certainly never come across it but then I run a bull breed rescue and rarely have smallies and fluffies.

I've only ever seen it in Cavies.

Hamsters too -happens if you breed the wrong colours together.

I'm sure it is genetic, was just trying (badly) to say that it is likely, if humans are anything to go by, that the gene responsible will be different in many different cases (between breeds, and maybe between individuals of same breed), making a readily available test difficult.  So whereas something like prcd-PRA test is widely applicable because PRCD is quite a specific problem, it may not be possible for something like this which can be the end result of many different problems.  Although if numbers affected are increasing, maybe someone could develop a breed specific test?  I'd be interested to hear too if anyone knows of any research in that direction :-D
Clare

Aaaah!   That's it Marianne!

It was a mating of two Dalmation cavies.

Much the same in hamsters -it's white bellied or roans you can't mate together (same gene).

Am with you now CVL ;o).

I googled Microphthalmia and Pomeranians and was surprised at the result. Apparently the merle factor strikes again. However, the little chap here is not merle? I know next to nothing about genetics as I do not breed so it's all pretty much double Dutch to me. But I am intrigued by the whole "affair" and will do more digging.

I didn't even know it could exist in dogs, but how it works in hamsters, with the roan gene (similar to merle) the affected babies will all be pure WHITE in colour, never anything else. So I'd guess in a dog if it is related to merles, it doesn't have to mean the affected pup is of the colour, just that the parents were.

I've been in Pom's for 30 years and never had one with eye problems.  Umm the merle gene????  So in reality there's been another breed added as it's only in recent years since America have been producing this and I suppose people in the UK may have imported dogs with this behind them maybe?

Here it comes again - the Merle gene!  Merle to merle breeding can result in a whole litter of what are called "fatal whites" - ie more than usual amounts of white over face/ears is often an indication of possible deafness/blindness from birth.

Isn't there an issue with merle is some colours being hidden?  it is visible on the skin at birth but then later looks like a normal colour so can end up inadvertently being put to Merle and issues resulting from a Merle to Merle?

We once had a foal born with micropthalmia.    We put it down to the next door farm spraying his field with a cocktail of herbicides, funcicides and pesticides on day 42 of gestation, when the eye buds were forming.    It was awful to see the poor thing.   

He was by a grey stallion out of a chesnut mare, so I'm wondering now, after the other posts, if that was a contributing factor.

There was a spate of poor babies in East Anglia somewhere born with the same condition at about the same time our foal was born - I'm still coming down heavily on the spray theory.....

Jo

There were a few cases of it in the very pale (almost white looking) golden retrievers several years ago, (late 1980's if I remember correctly).

Merle, grey and the very light colour coated breeds in dogs and I wonder if this applies to other types animals seem to suggest it might be linked to a pigment/genetic root cause. It might be that is it is like deafness in animals and is connected to coat colour.

Just been looking at some forms of microphthalmia in humans, and some of the syndromic types are associated with ocular albinism (and found one with general albinism)!  This is different from the kind I am familiar with, but I was intrigued by everyone's comments about merles and white coloured animals.  Maybe similar can be true in humans (just in case anyone is interested!).

I found this:
Yet another gene in the "blue" family that can cause health issues is merle. Merle can not be seen in dogs with an e/e genotype. This e/e genotype occurs commonly in Pomeranians since orange, red and white probably account for the majority of Poms. The problem is that M/M (homozygous merle) dogs are always deaf based on our studies. We recently genotyped 24 mostly white Australian Shepherds and all tested M/M (based on the Clark et al. 2006 PNAS published test) and all were deaf. A proportion of these dogs were also blind in one or both eyes since microphthalmia is another common side effect in M/M dogs. Although in many breeds it is possible to educate breeders to never breed two merle dogs together this advice is not possible to follow in Pomeranians since e/e dogs would not show the merle pattern. It would therefore be necessary instead to advise all persons who breed a merle dog to use only a black or sable mate or to have DNA testing done on their red, orange or white mate prior to breeding to be sure it did not carry merle.

A gentest for it costs 95 dollars in the States!

Ah knew it was an issue with a particular colour masking the merle.

Sorry, just so I can understand.  Brainless you amongst others seem to know what you're talking about here, so I'll direct at you! lol
Could that mean, does that mean, that a dilute blue gene could mask a merle gene?  (Forgive if my terminology incorrect).

(I'm just thinking of the other 'merle' thread and 'rare' colours).
Thanks

No e e is the red/yellow colouration.

I always thought "merle" is blue merle as in Great Danes etc So now I have no idea WHAT colour the little man is, maybe someone could shed some light?

http://209.85.48.11/3336/36/upload/p946824.jpg

I hope it's ok to post his pic here if not, I apologise.

He looks like a blue, as in this blue GSD.

Thisis a blue merle pom. (I can see a definite look of sheltie there! ;-))

His base colour is brownish red and the tips of the hair are black. However, he's only about 12 weeks old so is still in puppy coat. As I said before I usually do not have smallies and the whole "field" is new to me. I have passed on the info to the breeder who couldn't care less and accused me of lying. I told her to google it as obviously one or both of the parents carry the gen. Here is a frontal shot of him:

http://209.85.48.11/3336/36/upload/p946599.jpg

He looks like a dilute, but not a merle.

Thank you!

Apparently this is a blue pom (not blue merle) and looks to the untrained eye very similar to yours in colouring.

He does, doesn't he? I always think red when I think Pom, God knows why!

I am not even sure if the pup I've got here is a pure Pom. He appears to be quite big for the breed. But then again my general lack of knowledge about smallies comes ot the fore.

There are quite a few poorly bred large pomeranians about, the number of people that think my spitz (mittel) are poms is unbelievable even Jay whos a black/white parti oversize at 16inch! but then the vast majority of poms they see in my area are poorly bred :-(. In actual fact Poms,GS Klein,GS Mittel,GS Gross & Keeshonds are classed as varieties of the same breed by the FCI so I suppose they're right (not!!)

He actually looks like an orange sable to me, can't see Merle at all.  Have you another photo?

Anworth, if you look back not long ago you will actually see some well know Pom's in GS pedigrees.

Just looked at the other photo, where does Merle come into this????  He totally and utterly looks like an orange sable to me.  Would say though that his ears look a strange shape and he's a big big boy!

Yes, I know and if you look back long enough in Pom pedigrees you will see some GS LOL :-) Angela

I've got loads of pics of him ;), he's my special little man *gg*. And I am getting worried that I will lose my street cred as a bull breed lady *not*.

http://209.85.48.11/3336/36/upload/p946814.jpg
http://209.85.48.11/3336/36/upload/p946828.jpg
http://209.85.48.11/3336/36/upload/p946821.jpg

He's just like any other normal pup, plays with towels, teddies and rubber rings.

Definitely orange sable, no blue, no merle or I'll have to say that for the past 30 years we've been breeding either blues or merles!!  He certainly looks very happy, I do think though that he's not going to be of Pomeranian size.

Don't know whether you can tell properly but if you look at my website past and present Maestro was an orange sable, you can just about see the black on his back as it's a head shot.

Had this in a blenheim cavalier in the 80's, he also had juvenile cataracts!

My golden retriever has this she also has juvenile cataracts in both eyes. (interestingly she is a darker golden and i've also known of anyother darker golden - unrelated - with the same problem. )