Peripheral Vestibular Disorder (PVD):

What is Vestibular Disease: The term vestibular refers to the inner ear organs of the body. Vestibular disease in dogs is not a true “disease” as such but actually is a composite of various neurologic signs that occur as a result of a malfunction of some part of the vestibular system. This system is responsible for the maintenance of balance and the coordination of position of the head, eyes, neck and limbs in space. It can be either peripheral (PVD) or central (CVD) in nature and can be the result of a vestibular lesion or other disease like hypothyroidism (low thyroid function) or hyperadrenocorticism (abnormal excessive presence of adrenocortical hormones, especially cortisol in the body). Both types of this condition usually present with acute onset (suddenly) and a peripheral vestibular issue may follow a recent ear infection.Vestibular disease is defined as the sudden, non-progressive disturbance of balance. It is also known as old vestibular syndrome and canine idiopathic vestibular syndrome. It is usually found more often in older dogs than in younger ones.

Symptoms of Vestibular Disease in Dogs: This condition will likely present suddenly and can be central or peripheral in nature. The primary and most noted symptoms are: Head tilt to one side or the other Vestibular ataxia (lack of muscle control) often asymmetric (not equal on both sides) Tight circling, falling or rolling Spontaneous nystagmus (rapid involuntary eye movements) Nausea and vomiting similar to that of motion sickness Strabismus (misalignment of the eyes or the condition of having a squint) Disorientation Reluctance to walk or stand Leaning or falling in the same direction as the head tilt The most likely symptoms that you will note in your pet in regard to CVD: Depressed mental state in which the animal displays disorientation and poor interaction with other animals and humans Postural defects like the loss of normal strength and proprioception (the sense of knowing where your joints are in space or body awareness) The symptoms that will likely be most obvious to you, the owner, will be the head tilt and vestibular ataxia noted above. Seek medical care as soon as possible when these symptoms are noted. Types Vestibular disease is generally a condition that affects older dogs and is usually peripheral or central in nature. There are several types: Peripheral vestibular disease (PVD) usually produces leaning in one direction and increased resting nystagmus – this type involves the ear and nerves Central vestibular disease (CVD) usually produces a non-ambulatory animal with decreased resting nystagmus – this type involves the brain Congenital peripheral or central vestibular disease is very rare in puppies The dysfunction is more common in older dogs but can be secondary to a neoplastic lesion. The head tilt and positional strabismus is pretty much equal in regard to the symptoms noted in your pet in both types of vestibular disease in dogs.

Causes of Vestibular Disease in Dogs: There are a number of known or suspected causes of vestibular disease. Some of these causes are more serious than others and will require some sort of medical assistance or intervention to resolve. Middle ear or inner ear infections Drugs that are toxic to the ear, for example Metronidazole Trauma or injury Tumors (neoplasia) Hypothyroidism Vascular disease, for example, stroke – though a rare cause Depending on the actual cause of the episode, after a fairly fast onset of the clinical signs mentioned above, there could be a period of relatively rapid improvement of those symptoms and signs with minimal if any medical intervention having been required.

Diagnosis of Vestibular Disease in Dogs: Diagnosing this disease will require a neurological examination by your local veterinarian. He or she will need to determine if the vestibular issue is peripheral or central in nature. Here is what he or she will be looking for in the physical neurological assessment: CVD – Vestibular signs like body awareness on one side only, unilateral paresis (paralysis), altered mental status, cranial nerve deficits (especially those related to cranial nerve V and VII) PVD – Vestibular signs like body awareness as above, normal strength, normal mental status, cranial nerve deficits (cranial nerve VII and Horner’s only) There will likely need to be some diagnostic testing done as well: MRI of ears and brain CT scan and radiographs – ear infections are better seen and assessed via these imaging methods Blood pressure testing CSF (cerebrospinal fluid) analysis to help in the determination of the presence of inflammatory or infectious disease Testing for viruses versus protozoa Myringotomy (surgical infusion into the ear drum to relieve pressure or drain fluid) for middle ear infections BAER (Brainstem Auditory Evoked Response) to evaluate the hearing channels and pathways which are in close proximity to the vestibular pathways

Treatment of Vestibular Disease in Dogs: The treatment of vestibular disease in dogs is twofold: The underlying or root cause of the disease needs to be determined and treated. Your veterinarian will need to identify the possible cause so that she can develop a treatment plan. Supportive care comes into play as well in the form of things like: Intravenous fluids if your dog is dehydrated Anti nausea medication to prevent or limit vomiting The administration of a medication called propentofylline to hasten the brain’s natural ability to compensate after any unilateral vestibular damage occurs Close monitoring of your pet during treatment Antioxidants and essential fatty acids to assist the body’s healing powers Quiet environment if the nystagmus persists or if it goes away and then returns

Recovery of Vestibular Disease in Dogs: Research has revealed that there is some experimental benefit to be gained from the use of the medication propentofylline in rats as it has shown some increasing of the speed at which the brain is able to compensate after unilateral vestibular damage. If this medication option is utilized, then it will, of course, require close monitoring of your pet during treatment. Additionally, the nystagmus can make an occasional return suddenly and last for a brief period of time. If your pet experiences this symptom reappearance, you should keep your pet in a quiet environment during that period of time and you should monitor him closely. If the nystagmus persists, then your veterinarian will need to re-examine and re-investigate the physical condition of your companion. Depending on the cause and the type of vestibular disease identified, the end result could be permanent damage in which your beloved family pet displays a permanent head tilt, balance issues, and disorientation. There may be adjustments needed in the home environment and by the family to deal with any permanent physical or neurological damage following vestibular disease, in order to keep him safe.

An ME dog owner’s experience with PVD
“My 8-year old s/f German Shepherd Dog Shelby has had the worst last  2 weeks. She apparently had a severe episode of Peripheral Vestibular  Disorder 2 weeks ago. (Suddenly completely down and couldn’t walk,  head lolling all over, severe nystagmus.) We ended up taking her to a  24-hour veterinary specialty center about 2 hours from our home for  emergency treatment, mostly because we thought it was a stroke or  brain tumor.

In the course of diagnosing her PVD, chest x-rays showed megaesophagus  which when I asked how bad it was, the vet said 4 on a scale of 10. Up  until that point, we had no indication that there was a problem EXCEPT  that she had recently started belching prolifically at times. My  thought to myself at the time was that it sounded like her throat was  wide open.

At this point, the vet also said that there was a high possibility (80%) that she also had Myasthenia Gravis. She had been having some  issues with hind end weakness at home so this seemed to also fit the  dx. Because of her continued difficulties walking due to lack of  balance control, we didn’t do a tensilon test, but did send out a  blood sample for antibody titers. We also decided to put her on  Mestinon to help with the muscle weakness as she was recovering from  the PVD and a long hospital stay.

She was in the hospital for about 1 week and we were just going to  take her home when she spiked a fever of 104.7 and xrays showed  aspiration pneumonia. Before this, the PVD symptoms had been getting  steadily better. She was able to stand and walk with assistance for  short distances. But she was still very weak and tippy.

Also somewhere in her the MG titer test came back negative. We decided to keep her on the Mestinon in case it was a false negative because of early disease process with the plan to retest later.  So we finally brought her home this Thursday. When we left the vet’s  she was walking fairly good, she seemed to have a lot of drive to get  the hell out of dodge. When we got home, she made a beeline for the  water dish (she is absolutely ravenous about water). We have made up a  bed for her in the family room with lots of pillows to keep her head  elevated.

But our first day home has felt like a nightmare that won’t end. We  knew it would be hard to take care of her at home, but neither of us  could have imagined how hard. She is just very weak and trying to keep  her in any elevated position for 15 minutes is a struggle, let alone  trying to get her vertical. She is a very large shepherd (tall and  long, not fat) who should probably weigh over 100lbs but weighs about  85lbs right now. As far as we can tell, she hasn’t had any  regurgitation of food, but she is a pretty uncoordinated drinker and  coughs after drinking.

After struggling through 2 syringe feedings of i/d last night (she  won’t eat if you put the food in front of her, this from a dog who has  never willing missed a meal), and not getting nearly enough down her,  we gave her pepcid and mestinon (60mg) at 11pm. From 12pm until about  6am, she was salivating so much that it sounded like she was drowning,  and panting at an insane rate constantly. She is supposed to get the  mestinon 3 times daily, and her previously scheduled dose was supposed  to be at 4pm, but we weren’t home and able to give it to her until  6pm, so there was only a 5hr (instead of 8hr) window between those 2
doses. We don’t know if she did this at the hospital. When I called  they told us to keep her as upright as possible. This is pretty hard  to do for 6+ hours! My understanding is that the Mestinon is probably  causing the excessive salivation (and possibly stomach upset)and we  feel that it is no longer worth this potentially life-threatening side  effect.

So after all this, I don’t know what I’m looking for by posting our  story. Maybe just the opportunity to tell people who would understand  what we are going through.

It is very had to imagine that she is going to be able to pull through  all of this and return to any semblance of normal. It seems we have  hit a “perfect storm” of conditions that are just compounding each  other. We could probably deal with just the vestibular disease, or  just the megae, but both at the same time may be too much. We have  agreed that if she spikes a fever again, we are not going to continue  treatment.

But maybe a few questions:
1) What do you think of discontinuing the Mestinon?
2) Why does she continuously pant hard? Is this the pneumonia, some  meds, pain?
3) How long does it take to see improvement in the pneumonia?
4) What about the feeding tube route? Could she even get through the  surgery?
5) How do you know when enough is enough?

Is your vet absolutely sure that Shelby’s symptoms are attributable to PVD, or is it possible that MG is the cause? As you’ve said it is possible to get a false negative with MG and often, when the dog is retested 6 months later, the result is positive. I don’t have any personal experience of MG, but I do know, from what others in the Group have said, that the Mestinon dose is really difficult to get right and that too much can be as bad as too little. Having said that, it is a very useful drug and, with a little tweaking, you should notice an improvement. My understanding of PVD is that it can be a transitory condition and usually manifests itself by the dog walking round and round in circles.

If you are going to continue feeding Shelby by mouth you need to be sure that her food is pureed until it is completely smooth – this will often contain enough water to satisfy her. Any additional water needs to be thickened somehow – Thick-it or gelatin. Drinking plain water from a bowl on the floor will, inevitably, end in regurgitation. There are lots of ideas in the Files and the Photos section for keeping a large, older dog vertical. Gravity is our friend when our dog has an esophagus which is not pushing food down to the stomach.

If you decide to go for a feeding tube there are several of us in the Group who are doing this. Our Irish Setter, Theo. has been fed this way since December, 2009 and, without it, would certainly have died. It need not be permanent – it’s sometimes a very good temporary measure for getting much needed nutrition into your dog – but my advice would be not to leave it so late that Shelby is too weak to cope with the surgery. It sounds as though, at the moment, Shelby’s principle problem is the muscle weakness and that the ME might be reasonably manageable with the proper protocol. As for the AP, she will need to be kept on antibiotics for 4-6 weeks [these bugs from aspirated food and stomach acid are hard to knock out, and they will come back bigger, stronger and worse unless completely killed off]. Usually dogs respond very well and very quickly to treatment if it is started early enough. The panting you are seeing is probably due to the AP and should diminish once the infection is under control. Again, please look in the Files for full information on drugs and treatment.”