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Dr. K
Dr. K, Dog Veterinarian
Category: Dog Veterinary
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Experience:  13 years experience as Veterinarian
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My dog Kula has recently been diagnosed with Drop Jaw . It

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My dog Kula has recently been diagnosed with "Drop Jaw". It seemed as if everything fit her symptoms at the mouth, drooling, bloodshot whites of her eyes, no noticeable pain.    What we have been noticing is an increasing stagger in her movements and weakness.   We thought this might be due to dehydration because of her difficulty drinking so we've been administering electrolytes/fluids subcutaneously. Her staggering and listlessness is gradually getting worse. Any ideas or experience with this combination of symptoms?
Hi Mike Napoli,

For how long has she been this way?
How old is she?

Dr. K
Customer: replied 8 years ago.
It's been one week since we noticed the open mouth and drool in her water bowl. She is 8 years old
Is she able to eat?
Is she having problems with regurgitation?
Is she up-to-date on her rabies vaccination? When was her most recent one given?

Customer: replied 8 years ago.
She can eat when I give her soft food. She has been eating 1/2 a can a day + 2 Beggin' Strips since this started last week.
She hasn't been throwing up, however she does gag like she's clearing her throat periodically
She received her last rabies vac < 2 years ago
Did the veterinarian that "diagnosed" her with the dropped jaw take any X-rays of her chest. If so, were they normal?
Customer: replied 8 years ago.
there haven't been any x-rays done.
There are a few possibilities for what may be going on here. Keep in mind, however, that without me being able to see and examine her, I can only make suggestions.

A "dropped jaw" is an inability to close the mouth. The two most common things that are going to cause this type of condition in dogs is a neurological problem called trigeminal neuritis and the infectious disease, rabies. Trigeminal neuritis has a sudden onset, but is not typically associated with other types of weakness. This problem is of unknown origin, and usually spontaneously resolves within 2-4 weeks.

The fact that your dog has weakness and staggering and gags a bit when swallowing, makes me concerned about rabies. So, unless you are certain that your dog absolutely could not have come into contact with a rabid animal (another dog, cat, raccoon, bat, rat, oppossum, fox, etc...) within the last 6 months....then I would leave rabies on the list of possibilities.

Another possibility here is that the dog does not have a truly "dropped jaw." Meaning, the jaw does have some muscle tone in it and she can close her mouth somewhat. If this is the case, then the rest of her symptoms may fit with a disease called myasthenia gravis. This disease is usually diagnosed first with administration of Tensilon (edrephonium choride). After the drug is injected, the dog will show a dramatic increase in muscle strength. Definitive diagnosis is made based on a serum AChR antibody titer.
Most dogs are treated as inpatients until adequate dosages of anticholinesterase drugs are achieved. In dogs that have complications due to aspiration pneumonia (if the dog has megaesophagus on presentation), intensive care may be necessary. If the patient is unable to eat or drink without significant regurgitation, they often need a special tube called a gastrostomy tube placed to help them do this.
Although this disease is treatable, most patients require months of special feeding and medication. The drug of choice is called Mestinon syrup (pyridostigmine syrup). Other drugs that are used are corticosteroids (if there is a poor response to pyridostigmine or if there is no response to the Tensilon test). I do not know of any holistic type remedies that have been found efficacious for treating this disease.
In cases where a mass is found inside the chest (a cranial mediastinal mass), surgical removal is performed. The patient must be stabilized on anticholinesterase drugs before this is done.
Once approprate drug levels of the anticholinesterase have been reached, return of muscle strength should be evident. X-rays of the chest are generally done every 4-6 weeks to evaluate for resolution of the megaesophagus. AChR antibody titers are evaluated every 6-8 weeks to look for a decrease back into the normal range.
If there is no severe aspiration pneumopnia or pharyngeal weakness, then there is a good prognosis for complete recovery. Resolution of clinical signs will usually occur within 4-6 months. If a thymoma is present, there is a guarded prognosis unless complete surgical removal and control of the myasthenia symptoms are achieved.

I am attaching some client information handouts that I use in my practice that discuss some of these conditions in more detail. I hope that you find them useful.

Myasthenia Gravis

If your vet has been unable to diagnose your dog, then you may want to consider asking them for a referral to see a specialist in veterinary internal medicine or veterinary neurology. Most specialists are located at referral centers or colleges of veterinary medicine. The benefit of seeing a specialist, is that you are more likely to get a quick and accurate diagnosis of your animal's problem, and thus a faster resolution of the symptoms. It is also more likely that a specialist has seen this problem before and treated it successfully.

Here is a link so that you can search for an internal medicine specialist in your area:

I hope that this information is of help to you, and I wish you the best of luck with your dog. Please let me know if I can be of further assistance.

Dr. K
Dr. K and other Dog Veterinary Specialists are ready to help you
Customer: replied 8 years ago.
Thank you for your help. She has developed nystagmus in certain positions. Her wobble is sporadic and recently she has begun shaking periodically. Her personality is the same happy little girl we know but she is sluggish and less responsive. Her appetite is good and we are giving her 500 ml sub q daily. We are having blood tests and the Acetylcholine serum test (won't have results for 2 weeks). What is this periodic shaking, slack jaw, nystagmus, gagging, staggering little doggy to do?
If the vet gave her a tensilon test, you would know right away if she had the myasthenia. Then you would not need to wait for 2 weeks to treat her for it. I think that this should be the first thing to discuss with your vet.

Dr. K
Dr. K and other Dog Veterinary Specialists are ready to help you
Customer: replied 8 years ago.
Thank you, XXXXX XXXXX mentioned to our vet about the tensilon test. She said they do not have that medication because it is only for myathenia gravis. I appreciate your expertise. I realize it is difficult to diagnose these things from afar, however, I find it very helpful to be able to inquiry about her condition with another doctor.

As a recap, the order of her symptoms have been:

1) Slack jaw/difficult swallowing associated with lack of jaw strength/control. (day 1- )
2) Slight to mild staggering, nystagmus in resting position and on back or sides. one side more than the other. (day 2- )
3) Periodic gagging (day 3- )
4) Periodic Hind quater tremors on inhale (day 5- )
4) Periodic body tremors on inhale (day 6- )
5) Vomitting of bile (day 8- )

Other than these obvious issues, she seems herself...easy to wag, responds happily to our attentions, semi- perky albeit lethargic. Eats 1/2-3/4 can soft food + 2-3 Beggin Strips. Drinking and jaw movement seem to be improving slightly. We are still giving her 500 ml of electrolyte/fluid every 48 hrs.

The diagnosis possibilities have been far and wide:

Trigeminal Neuritis
Myacenia Gravis
Vestibular Syndrome
Cancer of the brainstem area

As mentioned we are having the senior blood panel done and results should be available today. The acetylcholine serum won't be available for 2 weeks. I'm aware an MRI would be the ideal test to perform, however, funds are tight. If you can possibly shed any additional light on her related symptoms and behavior, it would be greatly appreciated. Perhaps in the order of your educated "gut" feel. How do the tremors fit in? How does the vomitting fit in? How does her slight jaw improvement fit in? How does the nystagmus fit in?

Any and all information is appreciated and will be compensated for. I can do $15 this time if that is acceptable to you.

Thank You
Hi Mike,

What breed is Kula?
You mentioned megaesophagus on the list that you gave me before.....did your vet do a chest X-ray and find megaesophagus?

Dr. K
Customer: replied 8 years ago.
Kula is a mix breed of Beagle and unknown. The vet didn't do an X-ray yet as she wanted to get the senior blood panel back to determine the safety of administering anathesia. She has not definitively been diagnosed with anything in particular yet.
Kula should not anesthesia to take on X-ray of her chest. It would be very helpful to have this chest X-ray done because if she has a megaesophagus, that will clearly be seen on a chest X-ray. If she does have megaesophagus, then this would much more strongly support a diagnosis of Myasthenia Gravis.

Based on all of her symptoms and her age, I do no think that she has Geriatric Vestibular Syndrome. She is not old enough for this, and it does not cause dropped jaw. So, I would not consider this high on the list. Also, dogs with vetstibular syndrome tend to get better within 72 hours of the beginning of the disease.

I doubt she has trigeminal neuritis, as this does not cause the weakness, vomiting, nystagmus, etc....

Nystagmus is not associated commonly with Myasthenia Gravis. If your dog is now adding this sign to the list, then she could have some type of encephalitis (brain inflammation).

What I strongly recommend that you to take your dog to see a specialist in veterinary neurology or internal medicine....Today. The specialist will have Tensilon to do the test right away, and the specialist will be able to decipher what is causing this problem much quicker and much more accurately than your regular vet. Your dog may not have two weeks to wait for these test results to come back.

If it is encephalitis that is causing this problem, this can be caused by many different things....some of them treatable and some of them not. It would be best for your dog to get diagnosed quickly and accurately so that treatment can be started right away. This would be her best chance at having a normal return to function.

I am attaching a handout that discusses encephalitis further:

Click Here

It is very hard for me to give you my "gut feeling" about what your dog has..because I haven't been able to examine her myself. However, based on the information that you have provided so far, I would say that some form of encephalitis or myasthenia gravis seem the most likely.

I really hope that she gets better soon,

Dr. K
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