Canine neoplasia--introductory paper.

The paper gives a brief introduction to canine oncology, including its comparative aspects as basis for recording tumours in the animal kingdom. In an abbreviated presentation of the Norwegian Canine Cancer Project for the years 1990-1998, the data (n=14,401) were divided into age groups, each of two years, into different categories of tumours, and into age and gender. As expected, cutaneous histiocytoma was the dominant tumour type in both sexes during the two first years of life. In the age group 2-3.99 years histiocytoma was still the largest group in males, but was surpassed by benign epithelial skin tumours in females. After the age of 4 years, benign epithelial skin tumours constituted the greatest circumscribed group in males, and mammary tumours in females, although the summated other tumours, not explained in this survey, dominated overall in males. Maligancies (cancer) were shown in the same way, by corresponding groups of gender and age. While mastocytoma was the most common tumour and non-Hodgkin's lymphoma the second most common during the two first years of life in females, the situation was reversed in males. Later, mammary tumours dominated in females, while different tumour types not further specified in this summarized report dominated in males, until the end of the age registration (above 14 years). Number, sex and location of most common tumours are shown in a tabular outline. Comparative aspects between human and dog tumours are considered: mammary and testicular neoplasia seemed more frequent in dogs than in humans in Norway, while intestinal, pulmonary and prostatic malignancies were less common in dogs. In our study, vascular tumours and tumour-like lesions constituted about 3% of the total data. As benign vascular tumours are incompletely reported to the human Cancer Registry, no dependable comparison may be made, but malignant vascular tumours have been on the rise during the last decades in the Norwegian human population, more so in men then in women. Finally, the article deals briefly with the development of endothelial cells, and the sparse information on causal factors of vascular tumours.

Canine vascular neoplasia--histologic classification and inmunohistochemical analysis of 221 tumours and tumour-like lesions.

A light microscopic evaluation of 221 canine vascular tumours and tumour-like lesions, supplemented by immunohistochemistry (von Willebrand Factor, CD31, vimentin), revealed a high degree of conformity with similar conditions in humans. Four main categories of tumours are reported, i.e. benign types: haemangiomas (n=127) and lymphangioma (n=1); tumour-like lesions: papillary endothelial hyperplasia (n=8) and vascular ectasias (n=2); neoplasms of intermediate malignancy: haemangioendotheliomas (n=27), and the obvious malignant form: angiosarcomas (n=57). Further classification showed that all subtypes had their human counterparts. Papillary endothelial hyperplasia and arteriovenous and venous haemangiomas are described for the first time in dogs. The combination of conventional histopathologic methods and immunohistochemistry was in many cases very useful diagnostically, the latter technique being in some cases indispensable for establishing a definite diagnosis. In general CD31 was the most useful marker for tumours originating from endothelial cells, especially for poorly differentiated haemangiosarcomas.

Canine vascular neoplasia--a population-based clinicopathologic study of 439 tumours and tumour-like lesions in 420 dogs.

This paper deals with a population-based material collected during the years 1990-1998, and comprises 439 tumours and tumour-like vascular processes from 420 dogs. Anatomic location, age, breed and gender are reported. A distinction is made between benign neoplasms, tumours of intermediate malignancy, and obvious malignant processes (angiosarcomas). Clinical behaviour, comprising recurrence and metastatic disposition, is included. Subclassification is done according to criteria used in human oncology. More than one half (242 of 439) occurred in the skin, and a great majority of skin processes (223 of 242) represented benign tumours or tumour-like lesions. The next most common site of summarised lesions was the spleen, with 110 cases, with only 17 processes in this organ being defined as benign. Splenic involvement was followed by the liver, with 13 out of 17 processes being angiosarcomas. Eleven of 12 heart tumours were angiosarcomas. A majority of skin haemangiomas was of the cavernous type (108 of 211), and more than one half (10 of 14) of the capillary haemangiomas were located on dorsal sites of the extremities. The mixed capillary/cavernous haemangiomas had a more diffuse distribution, although 20 of 31 were found in the skin of the hind limbs. Only one lymphangioma and one case of angiomatosis were observed. Most tumour-like proliferations were papillary endothelial hyperplasias. Recurrence occurred in 17 dogs, some of which had received a primary benign diagnosis. Primary metastases were observed in 63 animals, the majority in the spleen and heart. Dissemination involved a further 23 cases (22 had angiosarcoma). The male/female rate of benign tumours was 0.78, for tumour-like processes 1.83, intermediate malignant tumours 1.65, and angiosarcomas 1.60. With few exceptions, there was an overweight of all subclassified vascular lesions in animals more than 6 years of age.

Serum amyloid A protein forms a complex with a fragment of apolipoprotein A-I in the domestic blue fox: a protective mechanism against AA amyloidosis?

The spontaneous occurrence of protein AA-type of amyloidosis varies among animal species. As reactive AA-type of amyloidosis has never been detected in the blue fox, we obtained acute phase sera to search for amyloid-protective elements. The purified SAA fraction was characterized by mass and sequence analyses to disclose any unique domains in the amino acid sequence. The data revealed an SAA protein with heterogeneities in several positions, and showed the typical insertion between positions 69 and 70. By comparing the amino acid sequence with that from other mammals, no unique sequence could be observed. However, a C-terminal fragment of apolipoprotein A-I (ApoA-I) was found attached to the SAA. The amino acid sequence of the ApoA-I fragment revealed a partially blocked and ragged N-terminus. A comparison of the amino acid sequence of ApoA-I with that from the dog showed that the ApoA-I fragment started about position 190, had an intact C-terminus, and showed an identical sequence in all positions, except one. Based on the data, we suggest an interaction of the C-terminal fragment of ApoA-I with the SAA protein that inhibits the AA fibrillogenesis in the blue fox.

Lipoprotein lipase in the kidney: activity varies widely among animal species.

Much evidence points to a relationship among kidney disease, lipoprotein metabolism, and the enzyme lipoprotein lipase (LPL), but there is little information on LPL in the kidney. The range of LPL activity in the kidney in five species differed by >500-fold. The highest activity was in mink, followed by mice, Chinese hamsters, and rats, whereas the activity was low in guinea pigs. In contrast, the ranges for LPL activities in heart and adipose tissue were less than six- and fourfold, respectively. The activity in the kidney (in mice) decreased by >50% on food deprivation for 6 h without corresponding changes in mRNA or mass. This decrease in LPL activity did not occur when transcription was blocked with actinomycin D. Immunostaining for kidney LPL in mice and mink indicated that the enzyme is produced in tubular epithelial cells. To explore the previously suggested possibility that the negatively charged glomerular filter picks up LPL from the blood, bovine LPL was injected into rats and mice. This resulted in decoration of the glomerular capillary network with LPL. This study shows that in some species LPL is produced in the kidney and is subject to nutritional regulation by a posttranscriptional mechanism. In addition, LPL can be picked up from blood in the glomerulus.

Splenic ellipsoids: an early target for deposition of AA amyloid induced in mink.

The spleen is the primary target for spontaneous as well as experimental AA amyloidosis in animals such as mice and mink, and is therefore a valuable organ for study of the initial phases of amyloid fibrillogenesis and deposition. We have investigated splenic amyloid AA deposits induced in the mink, and we demonstrate a novel target for AA, namely the splenic ellipsoids. We show presence of amyloid P component (AP), glycosaminoglycans (GAGs) and apolipoprotein E (apoE), all well-known common elements of amyloid, co-localizing with AA. In addition, apolipoprotein AI (apoAI) was seen co-localized to the AA deposits in the ellipsoids. We hypothesize that the ellipsoids may be important splenic structures for initial AA formation. The apoAI in the ellipsoids could displace SAA from acute phase HDL at this site, thereby making SAA available for amyloid formation and deposition.