November 19, 2017

Restored vision in a young dog following corticosteroid treatment of presumptive hypophysitis

Hypophysitis is a term that covers a series of disorders related to the inflammation of the pituitary gland. Hypophysitis is a rare disease with only five documented cases found in dogs. This is the first case of presumptive hypophysitis induced blindness in a dog.

This article is a case report on a 1 year and seven-month-old neutered male Standard poodle presented with subacute blindness, ataxia, and polyuria/polydipsia (PUPD), which is related to diabetes insipidus. The poodle was initially brought to the veterinarian with PUPD, shivering and a fever. After 8 days from the initial visit, the dog developed subacute blindness and ataxia, the loss of control of body movements. After getting an MRI, the scan showed a pituitary mass (15mm height) that was affecting the optic chiasm, differentiating that it must be pituitary neoplasia (presence of a new, abnormal growth of tissue). In order to treat the mass, the owner settled on medical treatment and radiation therapy. The dog was first put on prednisolone, a drug that can treat conditions related to inflammation. As a result, movement and sight were improving.  Nine days after being on this medicine, the dog’s eyesight had greatly improved, becoming completely visual, but the PUPD persisted. In order to treat the PUPD, desmopressin (a drug that can treat diabetes insipidus) was prescribed.  Two days later, the dog improved with the administration of both prednisolone, bringing down the inflammation, and desmopressin, treating the PUPD. Later, another MRI scan showed that the pituitary mass has greatly decreased to within normal levels with the oedema and compression subsiding around the surrounding tissues. The dog has been normal for 14 months and treatment free for 11 months.

The diagnosis is presumptive hypophysitis because in order to confirm it is hypophysitis, a histopathological confirmation test would need to occur. According to past cases, this case most closely resembles that of the German Longhaired Pointer with lymphocytic hypophysitis. There were some differences between these two cases. One difference was that the Pointer did not experience vision loss, but that could be due to a smaller P/B ratio of the pituitary mass. The different outcomes could also be related to different factors. The outcome for the pointer was euthanasia, but the poodle recovered. This could be due to the age of the dogs as well as the quick administration of corticosteroids to the puppy. Also, the authors concluded that corticosteroid treatment could not be assumed to work for all presumptive hypophysitis cases. They believe that surgical biopsy would be the preferred measure to take before other treatment measures for pituitary masses.

Rzechorzek, N. M., Liuti, T., Stalin, C., & Marioni-Henry, K. (2016). Restored vision in a young dog following corticosteroid treatment of presumptive hypophysitis. BMC Veterinary Research, 13, 63.

Original Article: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5330113/pdf/12917_2017_Article_983.pdf

Reviewed by Hannah Cohen