Circulating thyroglobulin measurements by homologous radioimmunoassay in dogs with thyroid carcinoma

Post-surgical treatment of thyroid carcinoma in dogs with retinoic acid 9 cis improves patient outcome

The objective of the present study was to compare the effects of isotretinoin 9-cis (RA9-cis) as a post-surgery treatment of thyroid carcinoma to a traditional treatment (doxorubicin) and no treatment. Owners who did not want their dogs to receive treatment were placed into the control group A (GA; n=10). The remaining dogs were randomly placed into either group B (GB; n=12) and received doxorubicin at a dose of 30 mg/m² every three weeks, for six complete cycles or group C (GC; n=15) and treated with RA9-cis at a dose of 2 mg/kg/day for 6 months. The time of the recurrence was significantly shorter in the GA and GB compared to GC (P=0.0007; P=0.0015 respectively), while we did not detect differences between GA and GB. The hazard ratio of recurrence between GA and GB compared to GC were 7.25 and 5.60 times shorter, respectively. We did not detect any differences between the other groups. The risk ratio of recurrence was 2.0 times higher in GA compared to GC and 2.1 times higher in GB compared to GC. The type of carcinoma had an effect on time of survival with follicular carcinomas having an increased mean survival time than follicular-compact carcinomas (P<0.0001) and follicular-compact carcinomas had a longer mean survival time than compact carcinomas. The interaction among treatment and type was significant, but survival time in follicular carcinomas did not differ between treatments. In follicular-compact carcinomas the survival time of GC was greater than GB (P<0.05), but we did not detect a difference between GA and GB. In conclusion, this study shows that the use of surgery in combination with RA9-cis treatment significantly increases survival rate and decreases the time to tumor recurrence when compared to doxorubicin treated or untreated dogs. The histological type of carcinoma interacted with treatment for time to recurrence and survival time, with more undifferentiated carcinomas having a worse prognosis than differentiated carcinomas.

Endocrine diseases in dogs and cats: similarities and differences with endocrine diseases in humans

Over several millennia, humans have created hundreds of dog and cat breeds by selective breeding, including fixation of mutant genes. The domestic dog is unique in the extent of its variation in height, weight and shape as well as its behavior. It is primarily the relatively long persistence of high levels of growth hormone (GH) release at a young age that accounts for the large body size in giant breeds of dogs. Several of the endocrine diseases of humans are also known to occur as similar entities in dogs and cats. With some variations, this is true for conditions such as diabetes mellitus and the hypofunction syndromes of the thyroid and adrenal cortex. Also, the hyperfunction syndromes of hypercortisolism and hyperparathyroidism in dogs and cats have many similarities with their human counterparts. The exception seems to be Graves' disease. This condition, which is due to production of thyroid-stimulating hormone (TSH)-receptor antibodies, has not been observed in dogs and cats. The very common form of hyperthyroidism in cats is due to toxic adenomas. In the 1980s it was discovered that in dogs exogenous progestins and endogenous progesterone can induce GH excess. This GH excess originates form the mammary gland and may give rise to acromegaly and insulin resistance. GH production by the mammary gland is not unique to the dog. It has become clear that cats and humans also express the GH gene in the mammary gland. There is increasing evidence that this locally produced GH not only plays a role in the morphologic changes of the mammary gland associated with the ovarian cycle and gestation, but that it is also involved in the development of breast cancer. In dogs, induction of mammary GH production by progestin administration allows for treatment of GH deficiency.

Characterization of and radioimmunoassay for canine thyroglobulin

Canine thyroglobulin (cTg) has been isolated and purified. It has similar electrophoretic patterns as Tg from other mammalian species. The main fraction had a MW of 660,000, whereas also fractions of a MW of approximately 1,300,000 (dimer) and 330,000 (subunit) were present. The iodine content was 0.8 to 1.0% (w/w). cTg did not cross-react with antibodies against human Tg to a degree that would allow the use of a radioimmunoassay for human Tg for the determination of cTg in serum or plasma. Therefore a polyclonal antiserum was raised against cTg and a homologous radioimmunoassay was developed, which was sensitive (0.4 micrograms/l) and specific (cross-reactivity in cTg assay of human Tg, goat Tg, T4, T3, and DIT less than 0.01%). Plasma Tg levels in normal dogs of both sexes and aged 3-15 years amounted to 192 +/- 73 micrograms/l (mean +/- SD, n = 30). There was no relation between plasma Tg and T4 levels.