Thyroid Cancer in the dog: Attention to detail and timing is Everything!

By March 16, 2012Case Of The Month

We have been Missy’s health care provider for 11 years. She is a wonderful, gentle and intelligent English Springer Spaniel who represents joy and happiness at its very best.

Over the years she has lived a life enriched with infinite love and very few concerns. We have previously treated her for eye infections and a benign (non-cancerous) skin tumor.  Missy also had routine preventative dental prophies to maintain good oral hygiene.

On August 31, 2011 Missy visited our hospital with a swollen, inflamed and left hind paw. After taking a detailed history, the owner also mentioned she was drinking more water in the last few weeks and panting more often.  The owner authorized the appropriate diagnostics including a comprehensive blood profile to help investigate her increased drinking. Her annual wellness blood test was done in April 2011 and the results were normal -free T4 = 45.8pmol/L (thyroid value). However, now 4 months later she had an elevated free T4 which triggered an immediate concern with our veterinarians. Missy’s free T4 was 65.5pmol/L and the normal range in the dog is 7.7-47.6 pmol/L.  Additional testing revealed a very low thyroid stimulating hormone (TSH) which further supported an overproduction of levothyroxine (thyroid hormone by the thyroid gland).

On physical examination we found a mass in the area of the left thyroid gland.  Based on Missy’s blood results and palpable mass, our index of suspicion was very high that we were dealing with a serious aggressive thyroid tumor. Cervical (neck) ultrasonography and cytology was offered as part of the diagnostic work up.

The following steps were taken:

1) A detailed consultation with the owners outlined that thyroid masses in dogs are most likely a malignant tumor and are very invasive. Permission was given to procede with x rays and then surgery if there was no evidence of tumors in the chest.

2 The owners understood that surgical removal of a thyroid carcinoma is often  difficult because of the marked vascularity and the invasive nature of the lesion.  The good news is that despite the large size, the mass was freely movable on palpation and complications were expected to be minimal.

3) Pre-surgical thoracic (chest)  radiographs were done to evaluate her lungs and other thoracic structures for any obvious spread of the suspected cancerous mass into this area. The green light was on for surgery.

4) Surgical excision of the thyroid mass within the capsule was successful (Thyroidectomy-extracapsular technique).  The recovery was uneventful.

5) The pathologist reported a Thyroid follicular carcinoma and that the  tumor did not extend beyond the margins…this was very exciting information for ALL!

Key Points:

– Follow the symptoms: Missy’s increased water intake and more frequent panting truely were symptoms of this tumor. The majority of owners know their dogs normal patterns.

-Missy is an excellent example of why veterinarians obtain a detailed history and provide a thorough physical examination.

-Although no connection to the thyroid cancer it was the inflamed paw, a detailed assessment by our doctors, appropriate blood tests and going that distance that saved Missy’s life.

We have given Missy a very good prognosis that life will continue to be special in her senior years with the family.

Owners Comments 7 months post-surgery:

“We came with a totally unrelated problem.”

“It has been months and she is totally fine. ‘

“Missy always gets a complete body massage daily and we still did not detect the lump. This head to toe massage is a daily ritual and part of our quality time with her.

“Thank goodness we caught the cancer in time.”

“No matter how small things might appear to be….have it checked out even if it proves to be nothing at all.”

“We are so happy we still have our Missy!”

Update: April 2015-Missy remains healthy and has had only a minor vestibular crises in the past 6 months but has since fully recovered. Her only medication remains an immeasurable abundance of family love and a thyroid supplement daily.

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