Dear Dr. John,

Ever since I got a new kitten last fall, my 14-year-old cat started to lose a lot of weight and so I had him checked. It was suggested that perhaps the food competition and stress of constantly being chased and the excessive play of the younger cat was the cause. My older cat continued to lose weight. I went back to the vet and blood tests were done, which revealed both an infection and a very high thyroid hormone. The vet said that the typical signs of high thyroid were absent, so it was odd. Due to cost constraints, I elected to use oral medications in pill form. The antibiotic was impossible. My vet suggested an antibiotic injection. Could I have chosen another route of administration? If the pills for the thyroid condition continue to be tough to give, what would you recommend? A.W.

Dear A.W.,

The introduction of new pets to others most often leads to good results but sometimes there can have varying degrees of negative outcomes.

While the diagnosis of hyperthyroidism in your older cat makes sense, the infection does not. Then again, perhaps it was a long-standing low-grade infection that led to an elevation in the white blood cell count. The typical conditions seen with hyperthyroidism include weight loss, enormous appetites, tachycardia or rapid heart rates, and possible accompanying renal changes. This goes to prove that even though various conditions have typical clinical signs, there can be a lot of variation from one patient to another. Luckily, treatment should allow your older cat to lead a healthy life for some time, even several years.

In cats that are difficult to medicate with antibiotics, there is an injectable that is effective for up to 14 days known as Convenia, which was probably used. Other routes besides pills could have been compounding into liquid or transdermal administration. My guess is that your cat is taking methimazole for the hyperthyroidism. This too can be compounded into tasty liquid form or made into a transdermal paste.  Hope this helps.

Dr. John de Jong is President of the World Veterinary Association. He owns and operates the Boston Mobile Veterinary Clinic and can be reached at 781-899-9994.