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Unequal Sized Pupils

I have a 4 1/2 month old blue eyes Aussie. He was playing and completely fine. Took about a 10 min nap and woke up with one pupil completely dialated and the other the size of a needle. He was still acting completely fine.

Emergency vet said they don't know what would have caused it but to keep an eye on him. Internet said head trauma or chemical reaction. Neither occurred. I was with him the entire day. The last med he took was NexGard three days ago. His pupils look the same after about an hour. Does this happen to Aussies and it's just more noticeable because he has blue eyes or is he having neurological problems? I have a call into him vet but can't get in til tomorrow. He is still acting completely fine.

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Nex Guard
by: Nancy

It is more than likely Nex Guard that caused his eye problems. Those flea and tick meds can not be tolerated by some Aussies and other breeds too. Our Aussie got seizures from Frontline Plus. Some dogs have even died from flea and tick meds. Also do not give them heartworm prevention meds as they do the same thing. Good luck to you. I hope your Aussie doesn't have any lasting effects from this flea and tick product. Hopefully his eye returns to normal once he is not given this again. Good luck!!!

DIALATED PUPIL
by: SANDY K

when my aussie was 3mo. old ,his eyes were fine in the morning then in the afternoon all of a sudden one of his eye pupils was the size of a pin and the other eye just fine.
i called the vet and was told to just watch it for a couple hours,and if no change bring him in.
well with in a couple hours both his eyes were back to normal and just fine.
it has never happened since then and i still have no idea why it happened then .

uneven pupils
by: debbie

my aussie had seizures at 6 years old we had to put him to sleep. there is a gene that some have called mdr1 you can send away for the test. if it comes back positive they cannot have certain medicines. just did the test today and mailed it in. the weekend that the seizures got the best of my toby he stayed in a vet hospital that weekend . when I picked him up they said one eye was dilated bigger than the other and yes that can be a problem, I now have a miniature aussie with two blue eyes and I just gave him nextguard I noticed the other day that one of his pupils was alittle bigger than the other.I hope I get this test back negative because I don't think I can go thru another aussie with problems. these are absoutly the best dogs ever, but come with a lot of health problems.

Having the same issue
by: Bethann

Our aussie pup is 4 months old today and we are having the same issue. She is a blue merles with one blue and one marbled eye. The first time it happened was a week ago, but she had run into a deck (she was playing with another dog and didn't stop quit in time) I noticed the change in her pupil size about 2 hours after the head trauma occurred and it took about 2 hours for it to go back to normal. Today when she woke up her pupil in her all blue eye was the size of a needle and her pupil in her marble eye was huge (this is the same way her eyes were the last time, all blue constricted, marbled dilated) but she hadn't suffered any head trauma, she literally just woke up.
Did you ever find out what was going on with your puppy?
We have a vet appointment the afternoon and I am a little worried. I am currently applying to schools to become a physician assistant and have learned a good bit about medicine and the eyes and while dogs are different than humans we have a lot of similarities in our organs and bodily systems. I have also been reading a lot online to try and see what could be causing this and some of the possibilities are terrifying. Now I know you can't believe everything you read online but I am still freaking out a bit.

Unequal Sized Pupils
by: Nancy

Yes it definitely is the Flea and Tick Spot-Ons. They are full of chemicals and are very dangerous to some of our pets (dogs and cats) Please do not use this poison on your pets. Go to our website at frontlineproductssilentkillers.com or our Facebook page at Frontline/Frontline Plus a neuro-toxic poison and see what it can do to your pet. It doesn't matter if it's a Frontline product or not. They are all poison. Be careful...

Unequal pupil
by: Diesel

I have an Aussie, he is s the smartest dog ever. He is amazing with the kids once he got past the puppy nipping stage. He is loyal and loves to play with my kids and all the neighborhood kids love to practice tricks with him. I'm his chosen person. He loves to be at my feet whenever possible.
Unfortunately, he is epileptic. Seizures are common in Aussies. We medicate him to prevent seizures as much as possible. It is very expensive for us (about $2500 a year for meds, vet visits and blood work.) But he is a member of the family so we do it.
I have noticed his pupils do this when he is going to have a seizure and for hours after he has had one.
Uneven pupils MAY BE associated with neurological conditions.
If you notice uneven pupils watch your dog, it may be a seizure warning or they may have had a small seizure you did not recognize. I hope this is not the case but if so hopefully it's helpful to know they are often treatable if your willing to pay for it.

DM
by: Anonymous

Having Aussies all my life I would recommend having your Aussie tested for DM, it's a nurelogical disorder and the test can be inexpensive, requested by mail and done with a cheek swab. If you purchase an Aussie make sure their parents have clear health certs. The MDR1 gene can also be a factor but if this has been cleared then please check for DM.

MRD1 Gene
by: Nancy

FYI The MRD1 gene has nothing to do with the poison in flea and tick products and epilepsy. Certain drugs should not be given to Aussies (and a few other dogs) with this MRD1 gene. The drugs your dog shouldn't be given if they have the MRD1 gene are: Acepromazine (tranquilizer and pre-anesthetic agent). In dogs with the MDR1 mutation, acepromazine tends to cause more profound and prolonged sedation. We recommend reducing the dose by 25% in dogs heterozygous for the MDR1 mutation (mutant/normal) and by 30-50% in dogs homozygous for the MDR1 mutation (mutant/mutant).

* Butorphanol (analgesic and pre-anesthetic agent). Similar to acepromazine, butorphanol tends to cause more profound and prolonged sedation in dogs with the MDR1 mutation.We recommend reducing the dose by 25% in dogs heterozygous for the MDR1 mutation (mutant/normal) and by 30-50% in dogs homozygous for the MDR1 mutation (mutant/mutant).

* Erythromycin. Erythromycin may cause neurological signs in dogs with the MDR1 mutation. A mutant/mutant collie exhibited signs of neurological toxicity after receiving erythromycin. After withdrawal of the drug, the dogs neurological signs resolved. There were no other potential causes of neurological toxicity identified in the dog.

* Ivermectin (antiparasitic agent). While the dose of ivermectin used to prevent heartworm infection is SAFE in dogs with the mutation (6 micrograms per kilogram), higher doses, such as those used for treating mange (300-600 micrograms per kilogram) will cause neurological toxicity in dogs that are homozygous for the MDR1 mutation (mutant/mutant) and can cause toxicity in dogs that are heterozygous for the mutation (mutant/normal).

* Loperamide (ImodiumTM; antidiarrheal agent). At doses used to treat diarrhea, this drug will cause neurological toxicity in dogs with the MDR1 mutation. This drug should be avoided in all dogs with the MDR1 mutation.

* Selamectin, milbemycin, and moxidectin (antaparasitic agents). Similar to ivermectin, these drugs are safe in dogs with the mutation if used for heartworm prevention at the manufacturer's recommended dose. Higher doses (generally 10-20 times higher than the heartworm prevention dose) have been documented to cause neurological toxicity in dogs with the MDR1 mutation.

* Vincristine, Vinblastine, Doxorubicin (chemotherapy agents). Based on some published and ongoing research, it appears that dogs with the MDR1 mutation are more sensitive to these drugs with regard to their likelihood of having an adverse drug reaction. Bone marrow suppression (decreased blood cell counts, particulary neutrophils) and GI toxicity (anorexia, vomiting, diarrhea) are more likely to occur at normal doses in dogs with the MDR1 mutation. To reduce the likelihood of severe toxicity in these dogs (mutant/normal or mutant/mutant), we recommend reducing the dose by 25-30% and carefully monitoring these patients.

Drugs that are known to be pumped out of the brain by the protein that the MDR1 gene is responsible for producing but appear to be safely tolerated by dogs with the MDR1 mutation:

* Cyclosporin (immunosuppressive agent). While we know that cyclosporin is pumped by P-glycoprotein (the protein encoded by the MDR1 gene), we have not documented any increased sensitivity to this drug in dogs with the MDR1 mutation compared to "normal" dogs. Therefore, we do not recommend altering the dose of cyclosporin for dogs with the MDR1 mutation, but we do recommend therapeutic drug monitoring.

* Digoxin (cardiac drug). While we know that digoxin is pumped by P-glycoprotein (the protein encoded by the MDR1 gene), we have not documented any increased sensitivity to this drug in dogs with the MDR1 mutation compared to "normal" dogs. Therefore, we do not recommend altering the dose of digoxin for dogs with the MDR1 mutation, but do recommend therapeutic drug monitoring.

* Doxycycline (antibacterial drug). While we know that doxycycline is pumped by P-glycoprotein (the protein encoded by the MDR1 gene), we have not documented any increased sensitivity to this drug in dogs with the MDR1 mutation compared to "normal" dogs. Therefore, we do not recommend altering the dose of doxycycline for dogs with the MDR1 mutation.

Drugs that may be pumped out by the protein that the MDR1 is responsible for producing, but appear to be safely tolerated by dogs with the MDR1 mutation:

* Morphine, buprenorphine, fentanyl (opioid analgesics or pain medications). We suspect that these drugs are pumped by P-glycoprotein (the protein encoded by the MDR1 gene) in dogs because they have been reported to be pumped by P-glycoprotein in people, but we are not aware of any reports of toxicity caused by these drugs in dogs with the MDR1 mutation. We do not have specific dose recommendations for these drugs for dogs with the MDR1 mutation.

The following drugs have been reported to be pumped by P-glycoprotein (the protein encoded by the MDR1) in humans, but there is currently no data stating whether they are or are not pumped by canine P-glycoprotein. Therefore we suggest using caution when administering these drugs to dogs with the MDR1 mutation.

* Domperidone
* Etoposide
* Mitoxantrone
* Ondansetron
* Paclitaxel
* Rifampicin

Same here, not on same med
by: Clare

My mini is 1 year old and is having the same issue. We have noticed it happens to her after intense play or when she is super excited (say for treats). She is on heartworm meds but I disagree with Nancy, as this happened even when she was a puppy before meds.

I am not sure what to do. There are no signs of seizure, but it is definitely neurological. The regular vet has not been helpful to us as her eyes were almost normal when we took her in.

Here is what we've had happen: 1st episode: after intense play (may have bonked head), eyes stayed that way for about 2-3 days (not as bad but still uneven). Another time: stayed that way for a couple of hours. Maybe 5 other times, just slightly different when excited for treats/play. Yesterday: big difference when I hid from her and she had to find me (her favorite game). Lasted only short time.

help
by: Anonymous

i was watching my Aussie blue Merle with light blue eyes, he's around 5 months old and i noticed that that one of his pupils was tiny and the other was normal..i know when i first got him that he banged his head on a door pretty hard to where the door came flying open..but he seemed fine. nothing really seems off with him he plays with my other dog all the time. should i be worried or is it this something that happens with blue Aussies?

Pupils of Unequal Size
by: Nancy

It more than likely came from the Nexgard. This is s poison and full of chemicals like all the other spot ons, collars and pills. Please don't use this again. Use only natural products. Please go to our website to the Natural Products page to see some examples. Our website is frontlineproductssilentkillers.com Good luck

Pupils of Unequal Size
by: Nancy

It doesn't matter if you have an Aussie or another breed, a male or female, a blue eyed or brown eyed fur baby. The reaction to all these chemicals are the same. It does cause seizures too. Some vets won't acknowledge that it was the chemicals but it has happened to too many of them after the application of these or the digestion of these to be a coincidence. No chemicals on Fur Babies, please.

Unequal pupils
by: B3cka3

I have an almost 3 year old blue merle standard Aussie with blue eyes. When she was younger (12 weeks - 9 months) she had the unequal pupils three separate times and each time I took her to the vet they did multiple eye exams, and neurological testing and could never find anything wrong. When she turned a year her pupils seemed to stay the same size until today out of the blue they changed with one super dialated and the other one a pin drop size but she still acts completely normal and an hour later her eyes are back to normal. It is the weirdest thing. But my vet can’t find anything wrong to create this. I wonder if just because her eyes are so blue is why it’s more noticeable.

Anisocoria
by: IHERDyou

This is not related to chemicals in nexgard and has been documented for years before those products even came out. Also, this has been reported in puppies who have not been given any heartworm or flea treatments or other "chemicals" as some would call them. Correlation in a few cases does not equal causation, although some like to point at "chemicals" and claim they cause everything wrong with this world, ever, which is just downright ridiculous.

It is most likely a neurological issue in light-eyed Border Collies and Aussies. The exact cause is unclear but is not likely terribly harmful and most seem to grow out of it with age.

This is an Aussie Condition
by: Anonymous

Hi, I’m a veterinary ophthalmologist and have seen this several times in both Mini and standard Australian Shepherds. It is young dogs only (under 1 year), resolves spontaneously within several hours, tends to recur 3 or 4 times—not always on the same side, and causes no harm. It appears to be a temporary loss of sympathetic tone on one side. This means that the dilating muscles stop firing for a while, leaving the constrictor muscle unopposed. Most I’ve seen have not been on any type of flea control.

same thing here
by: Anonymous

This just happened 30 minutes ago for the first time in our 15 week old Australian Shepherd. She hasn't had any flea medicine in over a month and is not on any meds.

She did just get her latest vaccines yesterday but had the same ones a month ago without any reaction.

We freaked out and called the vet hospital nearest us. She's playing and acting normal and had been playing pretty intensely with our other dog.

The comment from the veterinary opthalmologist is very helpful. We'll keep an eye on her and rush to the hospital if she starts acting funny or vomits.

similar problem
by: Anonymous

I have a 6 month old Mini Aussie puppy with similar concerns. Curious how everyone's dog who experienced this are doing now?

Constricted eye in 3 month old
by: Anonymous

I have a three-month-old red merle female Aussie. That this has happened to twice now in a span of two weeks. But opposite eyes. It usually resolves within 30 min to an hour. She is not on any medication of any kind. And I am not aware of any head trauma. And no chemicals involved. She acts totally normal when it happens and is her happy playful self. It was a bit of a relief reading what the ophthalmologist had to say on the matter. I will still keep an eye on her when or if an episode happens again.

Unequal pupils
by: Holly

Last night our 6 month old red merle Mini Aussie with blue eyes had unequal pupils. One pupil was the size of a pin and the other was big. He plays pretty hard with our other Mini Aussie pup (8 month old black tri) but I have no knowledge of him hitting his head or getting into any bad chemicals. After his pupils stayed that way for an hour or so, I got really worried and called the emergency vet. She told me that if he is acting normal (which he was) that it isn't a medical emergency, but I should take him to his regular vet today. When we woke up this morning his pupils were back to normal.

I found this website as I'm waiting for our vet appointment and it has been very comforting and helpful to know that other Aussies have had similar issues with their pupils. I've been a dog owner my whole life but these two pups are the first Aussies I've ever had. They are both such amazing dogs and the whole family loves them so much.

Similar issue
by: Anonymous

My 3 year old Aussie had this happen to her last night. She was fine one minute and the next minute I looked over and her left side eye was significantly smaller than normal (almost a pin drop size). I was freaking out as it was late at night and rushed her to the vet but they unfortunately had a 6 hour wait and I was told to go see her regular vet instead. She did tell me that in the meantime if she showed any neurological symptoms to bring her in right away, but I stayed up all night with my girl and her eyes returned back to normal after a few hours. She never showed any neurological symptoms and has not recently taken any heartworm or flea and tick medications. It is the weirdest thing and I will be taking her to the vet this week. My only concern is everyone stating that this only happens in young puppies but here I am with my three year old even more concerned since she isn’t that young.

Not an Aussie
by: Anonymous

Hi my dog isn't an Aussie but he has blue eyes so I figured I'd post this cause he is having same problem he took a nap woke up one eye was showing all blue then other solid black he was acting fine tho nothing out ordinary and I haven't used any flea meds on him or anything hope he is ok he is sleeping again now and I turned lights off maybe it will help I will update in couple hrs

Puppy’s eyes were dilated
by: Anonymous

My almost 4-month-old Aussie received his rabies shot today and now one pupil is bigger than the other. He’s acting fine. But I’ve been watching it closely and it’s slowly returning back to normal. I’m wondering if the shot had anything to do with it. Anyone else have advice or insight on this?

Unequal Pupils Update
by: Anonymous

In my previous post, my 6-month-old red merle Mini Aussie with blue eyes ("Jasper") had unequal pupils. The vet gave him a checkup and everything looked normal. Jasper is now 12 months old and still happy, playful, and healthy. I have not noticed his pupils being unequal again.

Both my Aussies (and my very old Chihuahua) take Nexguard and heartworm prevention medication. I live in NC where mosquitos and various parasites are active almost year round, so in my opinion the alternative is much worse for the dogs than any slight risk from the medication. For heartworms I do give the Aussies Interceptor Plus not Heartguard since the latter has an ingredient that may not be good for a dog with the MDR1 mutation. (I don't know if either dog has the mutation, but my vet prefers to treat them as if they do.) The Chihuahua has been on Heartguard since he was 6 weeks old and is still doing well at an advanced age. I don't believe for a second that these medications are causing unequal pupil issues.

3 Month Mini Aussie
by: Anonymous

Yes it is common in Aussies! The different sized pupils is new to me but my puppy has been tested for the MDR1 gene and is negative for it. His eyes resolved on its own in 30 minutes to an hour. No need to worry unless your puppy is acting strange. :)

Unequal pupil size
by: Anonymous

I have a 15 week old mini American Shepherd bought from Petco at the mall. He has had at least 4 episodes of unequal pupil sizes since @ January 10th. The last episode was 2 nights ago and was the shortest in duration. I have paid extra for blood work, bike acid tests and abdominal US to rule out any infections or "liver shunts". All tests have come back negative. The next option was to get an MRI ($4-5,000) or to presumptively treat as seizures. I feel much better after the vet ophthalmologist post! Thank you very much for sharing the information!

Temporary Anisocoria
by: RW

Our almost 17 week old blue eyed merle Australian Shepherd puppy has had temporary Anisocoria 3x in the last month and a half. All 3 times have been in evenings after she wakes up from a nap and resolves itself within the hour. She is otherwise acting completely normal. No signs of pain or issues. We have an older 9 year old aussie and they play tug of war a lot and we try to monitor how rough the tugs get until she is more full grown. We are going to get her checked out by a neurologist just in case but wondering how many others have had this happen? I've read they outgrow it and as long as there are no other symptoms is shouldn't be a cause for concern but I'd rather be safe than not. Any experiences or advice would be helpful if there are any vet neurologists/ophthalmologists on this thread. Thank you!

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