Pituitary Apoplexy in Dogs
What is Pituitary Apoplexy and What Does It Look Like?
Pituitary apoplexy is a clinical diagnosis caused by acute hemorrhage or infarction of the pituitary gland. The hemorrhage occurs secondary to neoplasia (benign or malignant). The hemorrhage is thought to occur because the tumor grew faster than the blood flow, or because of compression of the very sensitive blood vessels in the area of the pituitary gland. Apoplexy isn’t common with pituitary neoplasia, and rarely fatal, but remains an important possibility for patients with pituitary gland neoplasia. Clinical signs described on presentation for dogs with pituitary apoplexy include acute onset mentation changes (obtunded, stupor, coma:62%), cranial nerve deficits (65%), gastrointestinal signs such as vomiting or nausea (54%), gait changes such as circling, weakness/paresis, ataxia (85%), and hyperthermia (31%). Other signs such as bradycardia, and cervical hyperpathia were noted but less commonly. The GI signs are critical, and unique, and shouldn’t be ignored. They could be due to vestibular signs (present in about 15% of dogs), but also could indicate a rapid rise in intracranial pressure.
Do all Dogs with Pituitary Apoplexy have Endocrinopathy?
No! According to a recent study by Woelfel et al, only 50% of dogs with pituitary apoplexy diagnosed on either post mortem exam or presumptively diagnosed on MRI had an endocrinopathy. A further 12% had signs suggestive of an endocrinopathy but did not undergo workup. This means that 38% of dogs did not have clinical or biochemical evidence of an endocrinopathy. The endocrinopathies could be the obvious one (Cushing’s disease), or the less obvious (central diabetes insipidus, hypothyroidism).
Treatment and Survival
Dogs receiving radiation therapy survived longer than those medically managed. There is probably a bit of bias, however, because the severity of clinical signs likely steered clients or veterinarians towards or away from treatment. The use of hyperosmolar solutions (mannitol, hypertonic saline) was associated with a poorer survival. Again, this may be due to the severity of signs of those patients receiving this treatment rather than the treatment itself. No clinically useful markers were identified to predict survival in this study but that doesn’t mean they don’t exist; just stay tuned!
Take home message: Acute onset mentation changes with vomiting? Get those dogs to a neurologist (or get a consult!!) as soon as you can.
I hope you have a wonderful week! I look forward to seeing you soon!
Reference: https://doi.org/10.1111/jvim.16703