Answering your questions: Adult-onset neurodegenerative diseases in dogs and cats - Veterinary Medicine
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Answering your questions: Adult-onset neurodegenerative diseases in dogs and cats
Adult animals with progressive neurologic deficits merit a full diagnostic workup. Uncovering the cause leads to more informed treatment decisions and a more accurate prognosis.


VETERINARY MEDICINE


Q: What should practitioners tell clients about the prognosis for a pet with degenerative myelopathy?

The clinical course of degenerative myelopathy is reported to range from six months to three years, but this is influenced by the owner's decisions regarding the pet's quality of life and other contributing factors, such as degenerative joint disease. In general, affected dogs become nonambulatory in their pelvic limbs in six to 12 months from the first appearance of clinical signs.

Q: Are geriatric-onset seizures that don't seem to be progressing caused by neurodegenerative diseases? Or is a slowly expanding intracranial mass the most likely cause?

In most cases in which seizures develop in older dogs and cats (more than 6 years old), an underlying cause can be identified, even in those animals in which the frequency of the seizures is not changing. An intracranial mass would usually cause progressive signs, but it cannot be ruled out in stable cases without a full diagnostic workup. However, other important possibilities are that the animal had a vascular event that produced a seizure focus or that it has a low-grade inflammatory disorder. A full workup of these cases is desirable. If this is not possible, a minimum database should include a serum chemistry profile, complete blood count, urinalysis, fundic examination, and blood pressure measurement. It is unusual for a neurodegenerative disease to cause seizures. In addition, one could hypothesize that the ongoing neuronal loss associated with such a disease would cause neurologic abnormalities in the interictal period. Thus, if the animal is neurologically normal between seizures, a neurodegenerative process is less likely to be the cause.

Q: How can we best advise a client about the prognosis when he or she brings in a geriatric dog that's suddenly experiencing seizures?

The prognosis for patients with geriatric-onset seizures can only be given once an accurate diagnosis has been reached. It is common for owners of older animals to state that they only want to complete a full workup if there is a chance of identifying a disease that can be treated successfully. In this particular example, there are a number of diseases that can be treated, such as meningiomas, hypertension, and renal disease. If owners will not allow a full diagnostic workup, it is simply not possible to give an accurate prognosis. It is also true, though, that practitioners should not give a poor prognosis in such cases.

If the routine laboratory test results are unremarkable, blood pressure is normal, and no other neurologic abnormalities apart from the seizures are present, it is reasonable to prescribe an antiepileptic drug if the seizure frequency merits treatment. If the seizures are the result of a small infarct, for example, and respond to the antiepileptic drug, they may not affect the animal's life span. Obviously, identifying the underlying cause will always allow for more informed decisions about a patient's treatment and a more accurate prognosis.

Natasha Olby, VetMB PhD, DACVIM (neurology)
Department of Clinical Sciences
College of Veterinary Medicine
North Carolina State University
Raleigh, NC 27606

REFERENCES

1. Summers BA et al. Degenerative diseases of the central nervous system. In: Veterinary neuropathology, St. Louis, Mo: Mosby Inc, 1995;49-54.

2. Ellinwood NM, Wang P, Skeen T, et al. A model of mucopolysaccharidosis IIIB (Sanfilippo syndrome type IIIB): N-acetyl-alpha-D-glucosaminidase deficiency in Schipperke dogs. J Inherit Metab Dis 2003;26:489-504.

3. Summers BA, Cummings JF, De Lahunta A. Lysosomal storage diseases. In: Veterinary neuropathology. St Louis, Mo: Mosby Inc., 1995;214-236.

4. Olby NJ, Blot S, Thibaud J-L, et al. Cerebellar cortical degeneration in adult American Staffordshire Terriers. J Vet Intern Med 2004;18:201-208.

5. Higgins RJ, LeCouteur RA, Kornegay JN, et al. Late-onset progressive spinocerebellar degeneration in Brittany Spaniel dogs. Acta Neuropathol (Berl) 1998;96:97-101.

6. Steinberg HS, Troncoso JC, Cork LC, et al. Clinical features of inherited cerebellar degeneration in Gordon setters. J Am Vet Med Assoc 1981;179:886-890.


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Source: VETERINARY MEDICINE,
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