Guide To Australian Shepherd Training & Care

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

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