Effect of cyclooxygenase inhibitors in a xenograft model of canine mammary tumours.

Inhibition of cyclooxygenase-2 (COX-2) represents a possible avenue for the prevention and/or treatment of some cancers. Our goal was to compare the effect of a selective inhibitor of COX-2, deracoxib, and a COX-1 and -2 inhibitor, piroxicam, on the growth of canine mammary tumours in a murine model. CMT-9 was used to induce xenografts in nude mice. Mice were treated with piroxicam (0.6 mg kg(-1)), deracoxib (6 mg kg(-1)) or a control solution. Tumour volumes between 0 and 24 days post-treatment showed no significant difference between all groups. A second series of experiments was performed with a higher dose of piroxicam (0.9 mg kg(-1)). Tumour volumes between 14 and 21 days post-treatment were significantly smaller in piroxicam-treated mice compared with controls. These results demonstrate that COX inhibition reduced the growth of canine mammary cancer xenografts in mice, suggesting that COX inhibitors could have a positive effect in dogs.

Multicentric cutaneous neuroendocrine (Merkel cell) carcinoma in a dog.

Multicentric cutaneous neuroendocrine (Merkel cell) carcinoma was diagnosed in a 5-year-old castrated male Keeshond dog with multiple firm nodular cutaneous masses. The neoplastic tissue locally effaced the periadnexal and deep dermis and consisted of densely cellular confluent clusters of round to polygonal cells supported by a delicate fibrovascular stroma. The cells were moderately immunoreactive with chromogranin A, synaptophysin, and cytokeratin. Ultrastructurally, the cells had characteristic membrane-bound dense-core neuroendocrine granules approximately 120 nm in diameter and randomly dispersed throughout the cytoplasm. Effacement of dermal structures and multicentric distribution suggested low-grade malignant phenotype. These findings contrast with the typical benign behavior of canine cutaneous neuroendocrine tumors.

Cyclooxygenase-2 expression in normal and neoplastic canine mammary cell lines.

Mammary cancer is the most common cancer in female dogs. Induction of cyclooxygenase-2 (COX-2), a key enzyme in prostaglandins (PGs) biosynthesis, has been demonstrated in various cancers in humans and dogs, including mammary cancer. The objective of this study was to investigate the expression and regulation of COX-2 in canine mammary epithelial cells. Cell lines derived from normal and neoplastic canine mammary glands were cultured in the absence or presence of phorbol 12-myristate 13-acetate (PMA), and immunoblots, immunocytochemistry, radioimmunoassays, and a cell proliferation assay were used to study COX-2 expression and PGs production. Results showed that the neoplastic cell line CMT12 constitutively overexpressed COX-2 protein whereas other mammary cell lines expressed low to undetectable basal levels of COX-2 protein. Basal PGE(2) production was significantly higher (P < .05) in CMT12 compared to other cell lines. Levels of COX-2 protein in CMT12 decreased in a time-dependent manner with serum starvation, and PMA stimulation induced a strong time-dependent increase in COX-2 protein. Treatment of CMT12 cells with NS-398 (a specific COX-2 inhibitor) significantly blocked PGE(2) synthesis and reduced cell proliferation (P < .05). These results indicate that some neoplastic canine mammary cell lines constitutively overexpress COX-2, and that COX-2 inhibition decreases PGE(2) production and cell proliferation, supporting a role for COX-2 and PGs in canine mammary oncogenesis.

Ocular metastasis of a vaccine-associated fibrosarcoma in a cat.

A 6-year-old, neutered male domestic shorthair cat was evaluated for a recurrent vaccine-associated fibrosarcoma. The cat had three excisions of the tumour prior to presentation and was referred for radiation therapy. Ten months following treatment with radiation therapy, the cat was presented again for a cloudy appearance to the eye. An exenteration was performed, and biopsy revealed fibrosarcoma. At the same time, two discrete pulmonary nodules were identified on thoracic radiographs. Two doses of doxorubicin (20 mg/m(2)) and cyclophosphamide (100 mg/m(2)) were administered intravenously 3 weeks apart. Despite treatment, the pulmonary nodule doubled in size. This case represents the first antemortem report of ocular metastasis of a vaccine-associated sarcoma and supports the highly aggressive nature of these tumours.

Evaluation of the safety and efficacy of testicular biopsies in llamas.

Evaluation of the reproductive function of Lama glama is generally considered to be a challenging task due to the difficulty of obtaining representative semen samples. One method that has been proposed for evaluation of testicular function in these animals is histologic examination of testicular needle biopsies. This study was undertaken to examine the safety and efficacy of using needle biopsies to assess testicular function in this species. One randomly selected testicle from each of 16 sexually mature llamas was biopsied with a 14-gauge self-firing biopsy instrument. The llamas were evaluated over a 6-week period with thermography for temperature changes of the scrotum. At the end of the 6-week trial, the llamas were castrated and sections of each testis were fixed in Bouin's solution for histologic examination. Immediately prior to castration, an additional biopsy was taken from each testis to compare the tissue obtained via biopsy with sections from the corresponding testis obtained after castration. A qualitative grading scale was used to compare the seminiferous tubules from each testis. No difference was found between the biopsied and the nonbiopsied testes (P = 0.69). The percentage of normal tubules between the biopsied and the nonbiopsied sides also did not differ (P = 0.70). Furthermore, the percentage of normal seminiferous tubules did not differ between the needle biopsy samples and the corresponding tissue samples obtained at castration (P = 0.48). The number of round seminiferous tubules counted in each biopsy section ranged from 3 to 67. There was no significant difference in the thermographic images of the scrotum between the biopsied and the nonbiopsied testes. This study supports testicular biopsies as a safe and useful procedure in the evaluation of testicular function.

Effects of a bioactive glass on healing of closed skin wounds in dogs.

OBJECTIVE: To determine effects of intraincisional bioactive glass on healing of sutured skin wounds in dogs. ANIMALS: 9 purpose-bred mature female Beagles. PROCEDURE: 3 small matched bilateral (treated vs control) full-thickness truncal skin incisions were made and sutured. Treated wounds received intraincisional particulate bioactive glass prior to closure. Laser Doppler perfusion imaging was used to assess percentage change in tissue perfusion 3 and 5 days after incision on 1 set of 2 matched wounds, and skin and subcutaneous tissue-cutaneous trunci breaking strength were assessed at 5 days. The other 2 sets of wounds were used for histologic evaluation at 5 and 21 days, respectively. RESULTS: Subjective signs of gross inflammatory reaction were not detected in treated or control wounds. At 5 days, median subcutaneous tissue-cutaneous trunci breaking strength was significantly higher in treated wounds than in control wounds-(188.75 vs 75.00 g). At 5 days, median scores were significantly higher for neutrophils (1 vs 0), macrophages (2 vs 1), and necrosis (1 vs 0) for treated wounds than for control wounds. At 21 days, median macrophage scores were significantly higher for treated wounds than for control wounds (2 vs 1). CONCLUSIONS AND CLINICAL RELEVANCE: Bioactive glass in soft tissues does not cause a gross inflammatory reaction but causes an increase in histologic signs of inflammation, which decreases with time. Bioactive glass has potential for increasing tissue strength. Increased subcutaneous breaking strength could be beneficial in treating wounds in which early healing strength is needed.

Effects of a hydrolyzed collagen dressing on the healing of open wounds in dogs.

OBJECTIVE: To determine the effects of a hydrolyzed bovine collagen dressing (HBCD) on healing of open wounds in healthy dogs. ANIMALS: 9 female Beagles. PROCEDURES: 2 full-thickness skin wounds were made bilaterally on the trunk of each dog. Wounds on 1 side were treated with powdered HBCD covered with a semiocclusive nonadherent bandage. Wounds on the other side (control wounds) were covered with a semiocclusive nonadherent bandage only. Wound healing was subjectively assessed, and percentage increase in tissue perfusion was assessed by use of laser Doppler perfusion imaging (LDPI). Planimetry was performed to determine the percentages of contraction, epithelialization, and total wound healing. Biopsy specimens were examined microscopically to evaluate histologic changes. RESULTS: The HBCD did not induce a strong inflammatory reaction, as reflected by results of LDPI and histologic examination. Moreover, HBCD appeared hydrophilic and provided an environment to keep wounds clean and enhance early epithelialization. After treatment for 7 days, treated wounds had a significantly greater percentage of epithelialization than control wounds (12.13 vs. 7.03%). CONCLUSION AND CLINICAL RELEVANCE: The hydrophilic property of HBCD may cleanse contaminated wounds with the body's homeostatic fluids and enhance early wound epithelialization.

Evaluation of fibrin sealants in cutaneous wound closure.

Human fibrin sealant (HFS) and bovine fibrin sealant (BFS) were delivered as preformulated fibrinogen-thrombin mixtures that are light activated. These formulations were evaluated in the healing of incised cutaneous wounds in beagle dogs. Four groups were differentiated by sealant type and study duration with group: BFS for 10 days, HFS for 10 days, BFS for 30 days, and HFS for 30 days. Healing was evaluated by noting incidences of open wounds, laser Doppler perfusion imaging (LDPI), planimetry, breaking strength, and histopathology. In the absence of tension, both sealants tended to hold wound edges together; however, HFS tended to be better than its controls and BFS. Both sealants augmented suture closure, necessitating fewer sutures for wound closure. At 5 and 30 days BFS wounds had more perfusion than HFS wounds, indicating more inflammation. At 10 and 30 days BFS wounds had larger scar areas than their controls, while scar areas of HFS wounds were smaller than either BFS wounds or controls. Breaking strengths indicated that HFS wounds were stronger than their controls and BFS wounds. Histologically, mild to moderate chronic-active inflammation was observed in wounds receiving either sealant, and this persisted longer in BFS wounds. Overall, HFS had positive qualities, thus showing potential for functional and cosmetic wound closure.

Evaluation of treatment with a pulsed electromagnetic field on wound healing, clinicopathologic variables, and central nervous system activity of dogs.

OBJECTIVE: To evaluate effects of treatment with a pulsed electromagnetic field (PEMF) on healing of open and sutured wounds, clinicopathologic variables, and CNS activity of dogs. ANIMALS: 12 adult female Beagles. PROCEDURE: Open and sutured wounds were created in the skin of the trunk of the dogs. Dogs were divided into 2 groups. One group received PEMF treatment and 1 group served as untreated (control) dogs. The PEMF-treated dogs received treatment twice a day starting the day before surgery and lasting through day 21 after surgery. Wounds were evaluated by use of tensiometry, planimetry, laser Doppler perfusion imaging, and histologic examination. Clinicopathologic variables and electroencephalographic tracings were also evaluated. RESULTS: Use of PEMF treatment resulted in significantly enhanced epithelialization of open wounds 10 and 15 days after surgery. Five days after surgery, wounds of control dogs had a negative value for wound contraction, whereas PEMF-treated wounds had a positive value. The PEMF treatment did not cause significant changes in short-term planimetric, perfusion, tensiometric, histologic, clinicopathologic, or electroencephalographic results. CONCLUSIONS: The PEMF treatment enhanced wound epithelialization in open cutaneous wounds and provided indications of early contraction without significant short-term changes in other variables.

Ameloblastic fibrosarcoma in a bull.

This report describes a malignant odontogenic neoplasm in a 7-year-old bull. The mass, involving the right mandible, was locally invasive and destructive. Histologically, it consisted of islands and cords of benign odontogenic epithelium, entrapped in a population of malignant mesenchymal cells. These morphological features are characteristic of ameloblastic fibrosarcoma in man, an odontogenic tumour not previously described in animals.

Hormonal modulation of the physiologic responses of calves infected with Eimeria bovis.

OBJECTIVE: To determine whether an estradiol-progesterone (EP) growth implant would have an effect on febrile responses and on the catabolic component of Eimeria bovis infection. ANIMALS: 27 Holstein bull calves. PROCEDURE: Calves were assigned to treatment groups as: control (n = 5), EP implant (EP, n = 5), E bovis-inoculated (coccidia: C, n = 7), pair fed (n = 4), or EP plus E bovis-inoculated coccidia (EP/C, n = 6) groups. Calves were provided subcutaneous EP implants at 8 weeks of age, and were inoculated with 2 x 10(5) oocysts of E bovis at 11 weeks of age. Body weight was measured on postinoculation day (PID) 0, 14, and 28. Rectal temperature and food intake were determined and fecal samples were collected daily from PID 15 to 28. Blood samples were collected on PID 24 for analysis of CD2+, CD4+, and CD8+ antigens and plasma insulin-like growth factor I concentration. Blood samples were collected at 15-minute intervals for measurement of pulsatile growth hormone release. RESULTS: Group-EP/C calves had fever for 2 days versus 5 days for group-C calves (P < 0.05). These calves had diarrhea for fewer days than did their group-C counterparts (P < 0.05). Fibrinogen and glucose values were high in group-C (P < 0.05) but not group-EP/C calves. The latter had positive weight gain from PID 14 to 28, whereas group-C calves had weight loss (P < 0.05). Plasma insulin-like growth factor I concentration was reduced by infection (P < 0.05). EP-treated noninfected calves had increased numbers of CD2+, CD4+, and CD8+ blood mononuclear cells (P < 0.05). CONCLUSIONS: EP has a protective effect in calves infected with E bovis. This may relate to changes in immune function induced by EP. CLINICAL RELEVANCE: Treatment of calves with EP could offer some protection against the often severe wasting and debilitation associated with E bovis infection.

Invasive malignant fibrous histiocytoma in a cow.

An invasive malignant fibrous histiocytoma associated with the left cornual process, and causing lysis of the frontal bone, was diagnosed in a cow. The mass compressed the left cerebral hemisphere focally and extended into the frontal sinus and ethmoid and nasal turbinates. It was composed of pleomorphic to spindle-shaped cells with ultra-structural evidence of fibroblastic, myofibroblastic, and fibrohistiocytic differentiation. Trauma and chronic inflammation may be predisposing factors for development of neoplasia in cattle.

Metastatic multicentric neurofibrosarcoma of the lumbosacral plexus in a cow.

A metastatic multicentric neurofibrosarcoma of the lumbosacral plexus in an adult cow is described. The left lumbosacral plexus was obliterated by a mass which extended through the intervertebral foramen into the spinal canal and between the dorsal arches of the fifth and sixth lumbar vertebrae. A closely associated (possibly contiguous) mass extended into and separated the left sacroiliac joint. Multiple similar masses involved peripheral nerves and skeletal muscles of the pelvis, pelvic limbs, and abdominal wall. Metastatic lesions were scattered throughout the lungs. The lumbosacral lesion and all other masses consisted of interwoven bundles of loosely cohesive, elongated cells separated by variable collagenous matrix. Many neoplastic cells were positive for S-100 protein. Ultrastructurally, fibroblastic cells were mixed with scattered cells possessing schwannian characteristics.

Abortions, fetal death, and stillbirths in pregnant pygmy goats inoculated with tachyzoites of Neospora caninum.

Neospora caninum-induced abortion is a major production problem in the dairy cattle industry in the United States and worldwide. Abortions attributable to naturally acquired N caninum infection also have been observed in pygmy goats. We studied experimentally induced infections with N caninum in pregnant pygmy does to determine whether abortions attributable to N caninum infection would occur after inoculation. Seven pregnant pygmy does (1 control doe and 6 inoculated with N caninum) were studied. The control doe remained clinically normal throughout the study and delivered 2 healthy kids. Abortion, fetal death, and stillbirths were observed in some pregnant does inoculated with N caninum. Two pregnant pygmy does inoculated with N caninum early in gestation (day 51) had fetuses that died and were aborted, or died and were reabsorbed. Neospora caninum tachyzoites and lesions were observed in the brain, spinal cord, and heart of aborted fetuses; parasites also were isolated from the placenta. Four additional pregnant pygmy does (2 inoculated at mid-gestation [day 85], and 2 at late gestation [day 127]) did not abort after inoculation. However, 1 doe inoculated during mid-gestation delivered a stillborn fetus that had died about 1 week prior to parturition. This kid was congenitally infected with N caninum. Neospora caninum was isolated from the placentas of all inoculated does examined. Neonatal neosporosis was not observed in live-born kids, nor were stages of N caninum isolated from any live-born kid. Does did not undergo abortion or have congenitally infected kids when they were rebred and evaluated for neosporosis.

Luteinizing hormone releasing hormone, estrogen, and progesterone receptors in canine mammary lesions and tumor cell lines.

Nineteen canine mammary lesions were analyzed for estrogen receptor (ER), progesterone receptor (PR) and luteinizing hormone releasing hormone receptor (LHRHR) content. In addition, nine previously established canine mammary tumor cell lines with known ER and PR were analyzed for LHRHR. The incidence of receptors in the mammary tumor lesions was 21% for LHRHR, 10% for ER and 30% for PR. Statistical correlation was not observed between receptor status and diagnosis of malignant, benign, or hyperplastic lesions. A relationship between LHRHR and ER and PR content of canine mammary lesions or cell lines was not evident. The presence of functional hormone receptors offers opportunity for hormonal treatment of mammary cancer which may not be completely treatable by surgery. The observation of LHRHR in canine mammary tumors may offer therapeutic interventions other than surgery for mammary tumors unresponsive to antiestrogens.

Characterization of naturally occurring cutaneous neurofibromatosis in Holstein cattle. A disorder resembling neurofibromatosis type 1 in humans.

Neurofibromatosis in cattle is typically a noncutaneous disease. A small group of cows in a Holstein dairy herd developed cutaneous neurofibromatosis. This unique condition was investigated and compared with neurofibromatosis type 1 (NF1) in humans. All cutaneous lesions but one were consistent with neurofibromas in noncutaneous sites in cattle and neurofibromas in patients with NF1. One bovine lesion was classified as a neurofibrosarcoma. Immunohistochemistry and electron microscopy supported Schwannian differentiation in benign and malignant lesions. Linkage analysis with a polymorphism in the bovine NF1 gene confirmed that two affected animals from the same sire inherited the same paternal NF1 allele. Bovine cutaneous neurofibromatosis is a naturally occurring disease in this group of animals, characterized by skin tumors morphologically identical to those of NF1. An informative polymorphism at the NF1 locus of two animals and their sire suggests this disorder may be caused by hereditary mutations at the bovine NF1 locus.