Percutaneous ultrasound-guided chemical parathyroid ablation for treatment of primary hyperparathyroidism in dogs.

OBJECTIVE: To evaluate the efficacy, feasibility, and safety of ultrasound-guided chemical ablation of parathyroid masses in dogs with primary hyperparathyroidism. DESIGN: Prospective clinical trial. ANIMALS: 8 dogs. PROCEDURE: In all dogs, a solitary parathyroid mass was evident ultrasonographically. Dogs were anesthetized with propofol, and a 27-gauge needle was directed into the parathyroid mass under ultrasound guidance. Ethanol (96%) was injected into the mass until there was evidence of diffusion of fluid throughout the mass. Serum total calcium, ionized calcium, phosphorus, and parathyroid hormone (PTH) concentrations were monitored daily for 5 to 7 days after the ablation procedure and again 1, 3, and 6 months after the procedure. Dogs were also monitored for adverse effects. Follow-up ultrasonography was performed 5 days and 1 month after the ablation procedure. RESULTS: One injection was required in 7 dogs, and 2 injections were required in 1. Serum total and ionized calcium concentrations were within reference ranges within 24 hours after treatment in 7 dogs and within 5 days in 1 dog. Serum PTH concentration decreased and serum phosphorus concentration increased within 24 hours after treatment in all 8 dogs. Transient hypocalcemia developed in 4 dogs during the first 5 days after treatment, but only 1 dog required treatment for hypocalcemic tetany. Hypercalcemia recurred in 1 dog 1 month after the procedure and surgical removal of the parathyroid mass was required. Other adverse effects were not reported. CONCLUSIONS AND CLINICAL RELEVANCE: Ultrasound-guided chemical ablation of parathyroid masses is a safe and effective alternative to surgery for dogs with primary hyperparathyroidism.     

Effects of orchidectomy on bone metabolism in beagle dogs

The effects of orchidectomy on bone metabolism in male beagle dogs were examined using twelve 2-year-old dogs that were orchidectomized. The dogs' bilateral iliac bones, double-labeled with tetracycline and calcein for the histomorphometry, were obtained from three dogs prior to orchidectomy and at 3, 6, 9, and 12 months afterwards. The serum biochemical constituents related to bone metabolism were examined before and every month after orchidectomy. Between 1 and 6 months after orchidectomy, the value of serum testosterone decreased (1 month), while the levels of parathyroid hormone, calcitonin, total calcium, osteocalcin, and alkaline phosphatase activity increased significantly, indicating a high bone turnover. The mean trabecular thickness and the fraction of labeled osteoid surface decreased significantly 3 months after orchidectomy, but other histomorphometric parameters were unchanged. In the period 7-12 months after orchidectomy, the parathyroid hormone level increased ever and above that of the first 6-month period, while the levels of calcitonin, osteocalcin, alkaline phosphatase activity, and phosphorus decreased. The bone volume, mean trabecular thickness, and the fraction of labeled trabecular surface decreased significantly compared with the pre-orchidectomy values. These findings indicate an imbalance in bone metabolism (i.e. bone resorption > bone formation). These results indicate that a loss of bone volume accompanied the fall in sex hormone levels following orchidectomy and suggest that the orchidectomized dog is available as an animal model for studying osteoporosis caused by hypogonadism and the decline of sex functions in men.     

Physiologic effects of administration of interleukin 1 beta in cows.

The immunomodulating polypeptide interleukin 1 beta (IL-1 beta) has been shown to be homologous to osteoclast-activating factor and is capable of stimulating increased osteoclastic bone resorption. This effect prompted an investigation into the potential use of IL-1 beta for prevention of parturient paresis, a disease of dairy cows characterized by hypocalcemia and poor osteoclastic resorption of bone. Six nonpregnant cows were treated with a high dosage of IL-1 beta (166 ng/kg of body weight) every 8 hours for 4 days. The IL-1 beta treatment significantly (P < 0.05) increased urinary hydroxyproline excretion, an index of osteoclast activity, indicating that bone calcium resorption might be stimulated by IL-1 beta treatment of cows. However, IL-1 beta treatment also caused transient fever, inappetence, increased pulse and respiratory rate, and diuresis. The acute, but transient, effect of IL-1 beta treatment was to cause a decrease in plasma calcium and phosphorus concentrations. The pleiotropic effects of IL-1 beta administration negated the positive effects on osteoclastic bone resorption, and indicates that this cytokine may be of minimal benefit for prevention of parturient paresis.     

Biochemical indicators of bone metabolic activity in buffalo (Bubalus bubalis) during late pregnancy and early lactation

Blood levels of calcium, inorganic phosphorus, magnesium, osteocalcin, intact parathyroid hormone, calcitonin, alkaline phosphatase activity, creatinine and thyroid hormones were estimated in 10 healthy buffalo during late pregnancy (30, 15 days and 7 days before calving), within 12 h after calving and 7-15-30-45 and 60 days after calving. The almost constant serum levels of calcium, phosphorus, intact parathyroid hormone, and the low calcitonin concentration indicate that these buffalo need to utilize only a little of their endogenous mineral resources. Bone-turnover could be demonstrated by variations in the serum levels of osteocalcin and alkaline phosphatase activity. A study of these bone markers could be useful for other research purposes and for future clinical application in pathological conditions.     

Effects of calcium supplementation and sunlight exposure on growing beagle dogs

Nine 7-week-old Beagle dogs were given 2.3 g of dietary calcium supplementation once a day and were exposed to sunlight to permit endogenous vitamin D formation. After 70 days, the serum calcium and phosphorus concentrations, thyroid morphometry, and bone density and composition were compared with those values in a similar group of 10 dogs not given calcium supplementation and maintained in restricted, artificial light. Lower serum calcium and phosphorus concentrations in the supplement-fed dogs may be attributed to hypercalcitonism, which was assumed to be present because of increased proportions of C cells and decreased proportions of thyroid follicles. They also had significantly more trabecular bone of a lower specific gravity containing more water and less combustible matter. The findings indicate that the high dietary calcium intake and sunlight exposure induced C-cell hyperplasia during a relatively short period of 70 days. It is possible that Beagles maintained through maturity on a diet high in calcium concentration and in outdoor runs may develop chronic C-cell hyperplasia. The possible contribution of high calcium intake and chronic C-cell hyperplasia to reduced thyroid function and skeletal changes is not yet clear.     

Comparison of the effects of daily and intermittent-dose calcitriol on serum parathyroid hormone and ionized calcium concentrations in normal cats and cats with chronic renal failure

BACKGROUND: Chronic renal failure is complicated by secondary hyperparathyroidism, which traditionally has been controlled by dietary restriction of phosphorus and administration of phosphorus binders. Early treatment of patients with chronic renal failure with calcitriol may be indicated because once established, parathyroid gland hyperplasia does not readily resolve with therapy. HYPOTHESIS: Daily and intermittent dosing of calcitriol will decrease plasma parathyroid hormone concentration in normal cats and cats with chronic renal failure without causing ionized hypercalcemia. ANIMALS: Ten normal cats; 10 cats with chronic renal failure. METHODS: Phase 1 was daily calcitriol administration (2.5 ng/kg PO q24h) for 14 days. Phase 2 was intermittent calcitriol administration (8.75 ng/kg PO q84h) for 14 days. A 7-day washout period separated phases 1 and 2. Before each phase, calcitriol, parathyroid hormone, and ionized calcium concentrations were measured. On days 1, 2, and 3 of both phases, serum ionized calcium concentrations were measured. On the last day of both phases, calcitriol, parathyroid hormone, and ionized calcium concentrations were measured 0, 2, 4, and 6 hours after calcitriol administration. RESULTS: Overall, serum parathyroid hormone concentrations were significantly higher in cats with chronic renal failure than in normal cats (P = .022), but serum parathyroid hormone concentrations for both normal cats and cats with chronic renal failure were not significantly different before and after 14 days of treatment with calcitriol, regardless of whether calcitriol was administered daily or intermittently. Adverse effects of calcitriol administration (specifically ionized hypercalcemia) were not seen in either feline group during either phase of the study over the 3-day evaluation after calcitriol administration was initiated. CONCLUSIONS AND CLINICAL IMPORTANCE: At the dosages used, calcitriol treatment did not result in significant differences in serum parathyroid hormone concentrations before and after treatment in both normal cats and cats with chronic renal failure. With these dosages, adverse affects of calcitriol administration were not seen. Potential reasons for lack of apparent effect include small sample size, insufficient duration of study, insufficient dosage of calcitriol, problems with formulation or administration of calcitriol, and variable gastrointestinal absorption of calcitriol.     

Alterations in calcium, phosphorus and C-terminal parathyroid hormone levels in equine acute renal disease

The changes in serum and urinary levels of calcium and phosphorus and serum parathyroid hormone (PTH) were studied during controlled, chemically induced, acute renal disease in 4 ponies. There was an initial rise in daily urinary calcium and hydroxyproline excretion in 2 ponies which may have indicated increased bone resorption. Mild hypercalcemia, hypophosphatemia and elevated C-terminal PTH levels were associated with oliguria. Total daily urinary excretion of calcium and phosphorus decreased as oliguria developed. The levels of C-terminal PTH were increased in all four animals. This appears to have been related to their diminished renal function in that C-terminal fragments of intact PTH (which require functioning kidneys in order to be cleared) were probably being accumulated. Although there was no evidence with regard to an actual increase in PTH secretion, prolongation of intact PTH half-life due to renal tubular damage may have contributed to the development of hypercalcemia.     

Feeding 5-hydroxy-l-tryptophan during the transition from pregnancy to lactation increases calcium mobilization from bone in rats

An increasing demand for calcium during pregnancy and lactation can result in both clinical and subclinical hypocalcemia during the early lactation period in several mammalian species, in particular the dairy cow. Serotonin (5-HT) was recently identified as a regulator of lactation and bone turnover. The purpose of this study was to determine whether supplementation of the maternal diet with a 5-HT precursor would increase maternal bone turnover and calcium mobilization to maintain appropriate circulating maternal concentrations of ionized calcium during lactation. Female Sprague-Dawley rats (n = 30) were fed either a control diet (n = 15) or a diet supplemented with the 5-HT precursor 5-hydroxytryptophan (5-HTP, 0.2%; n = 15) from day 13 of pregnancy through day 9 of lactation. Maternal serum and plasma (day 1 and day 9 of lactation), milk and pup weight (daily), mammary gland and bone tissue (day 9 of lactation) were collected for analysis. The 5-HTP diet elevated circulating maternal concentrations of 5-HT on day 1 and day 9 of lactation and parathyroid hormone related-protein (PTHrP) on day 9 of lactation (P < 0.033). In addition, 5-HTP supplementation increased total serum calcium concentrations on day 1 of lactation and total milk calcium concentration on day 9 of lactation (P < 0.032). Supplemental 5-HTP did not alter milk yield, maternal body weight, mammary gland structure, or pup litter weights (P > 0.05). Supplemental 5-HTP also resulted in increased concentrations of mammary 5-HT and PTHrP, as well as increased mRNA expression of rate-limiting enzyme in 5-HT synthesis, tryptophan hydroxylase 1, and Pthrp mRNA on day 9 of lactation (P < 0.028). In addition, supplementation of 5-HTP resulted in increased mRNA expression of maternal mammary calcium transporters and resorption of bone in the femur, indicated by increase osteoclast number and diameter as well as mRNA expression of classical markers of bone resorption on day 9 of lactation (P < 0.048). These results show that increasing 5-HT biosynthesis during the transition from pregnancy to lactation could be a potential therapeutic target to explore for prevention of subclinical and clinical hypocalcemia.     

Primary idiopathic hypoparathyroidism in St. Bernard dogs

Primary hypoparathyroidism was diagnosed in three St. Bernard bitches. Anorexia, behavioural changes, muscle tremors, seizures, panting respiration, and cataracts were the clinical signs observed. The serum concentration of calcium was low, the phosphorus concentration elevated, and the immunoreactive parathyroid hormone level low in all dogs. The aetiology of the hypoparathyroidism was not determined in any of the dogs. Treatment with synthetic vitamin D (1,25-dihydroxycholecalciferol) and an oral calcium supplement was successful in restoring and then maintaining a normal concentration of serum calcium in two of the dogs.     

The persistence of antibodies against Brucella ovis and Brucella abortus in rams following vaccination: A field study

Primary hypoparathyroidism was diagnosed in three St. Bernard bitches. Anorexia, behavioural changes, muscle tremors, seizures, panting respiration, and cataracts were the clinical signs observed. The serum concentration of calcium was low, the phosphorus concentration elevated, and the immunoreactive parathyroid hormone level low in all dogs.

The aetiology of the hypoparathyroidism was not determined in any of the dogs. Treatment with synthetic vitamin D (1,25-dihydroxycholecalciferol) and an oral calcium supplement was successful in restoring and then maintaining a normal concentration of serum calcium in two of the dogs.     

Percutaneous ultrasonographically guided radiofrequency heat ablation for treatment of primary hyperparathyroidism in dogs

OBJECTIVE: To evaluate the efficacy and safety of ultrasonographically guided radiofrequency heat ablation of parathyroid masses in dogs with primary hyperparathyroidism. DESIGN: Clinical trial. ANIMALS: 11 dogs. PROCEDURE: In all dogs, either 1 or 2 parathyroid masses were evident ultrasonographically. Dogs were anesthetized, and a 20-gauge over-the-needle catheter was directed into the parathyroid mass via ultrasonographic guidance. Radiofrequency heat was applied to the stylet of the catheter until there was sonographically apparent change to the entire parenchyma of the mass. Serum total and ionized calcium and parathyroid hormone concentrations were monitored daily for 5 days after the ablation procedure and again at 1, 2, and 3-month intervals, if possible. Dogs were monitored for adverse effects. RESULTS: One treatment was required in 6 dogs, 2 treatments were required in 2 dogs, and treatment was unsuccessful in 3 dogs. Serum total and ionized calcium concentrations were within reference ranges within 2 days of the last procedure in all 8 successfully treated dogs. Serum parathyroid hormone concentration was decreased 24 hours after treatment in all 8 dogs. Hypocalcemia developed in 5 of the 8 successfully treated dogs, all of which required treatment. One dog had a transient voice change. Other adverse effects were not reported. CONCLUSIONS AND CLINICAL RELEVANCE: Ultrasonographically guided radiofrequency heat ablation of parathyroid masses is a safe and effective alternative to surgery in dogs with primary hyperparathyroidism.     

Functional analysis of ectopic parathyroid activity in cats

The ability of ectopic parathyroid tissue to support calcium homeostasis was evaluated by measuring serum concentrations of calcium, phosphorus, albumin, magnesium, and parathyroid hormone before and for 12 weeks after bilateral thyroparathyroidectomy in 14 cats. During the immediate postoperative period, significant decrease was observed in serum calcium, magnesium, and parathyroid hormone (PTH) concentrations. Serum PTH concentration remained subnormal and did not significantly increase during the 12-week observation period. Despite persistent hypoparathyroidism, serum calcium and magnesium concentrations gradually increased. Ectopic parathyroid tissue is not capable of maintaining normal serum calcium concentration immediately after thyroparathyroidectomy. Serum calcium concentration gradually normalizes after thyroparathyroidectomy, apparently by means of a PTH-independent mechanism.     

Long-term effects of intermittent equine parathyroid hormone fragment (ePTH-1-37) administration on bone metabolism in healthy horses

Intermittent administration of parathyroid hormone (PTH) is an anabolic therapy for osteoporotic conditions in humans. This study evaluated the effects of equine PTH fragment (ePTH-1-37) administration on bone metabolism in 12 healthy horses. Six horses each were treated once daily for 120days with subcutaneous injections of 0.5μg/kg ePTH-1-37 or placebo. Blood was collected to determine ionized calcium (Ca(++)), total Ca (Ca(T)), inorganic phosphorus, serum equine osteocalcin (eOC), carboxy-terminal telopeptide of type I collagen (ICTP), bone-specific alkaline phosphatase, and carboxy-terminal cross-linked telopeptide of type I collagen. Bone mineral density (BMD) was determined with dual X-ray absorptiometry of the metacarpus and calcaneus. Significantly higher blood Ca(++) and plasma Ca(T) concentrations were measured 5h after ePTH-1-37 administration compared to placebo. Higher serum eOC concentrations were found for ePTH-1-37 treatment at days 90 (P<0.05) and 120 (P=0.05). Significantly higher serum ICTP levels were observed with ePTH-1-37 treatment at days 60 and 90. For both study groups, BMD increased significantly in the calcaneus. Long-term use of ePTH-1-37 seemed to have no negative effects on bone metabolism in healthy horses. The absence of undesirable side effects is the premise to ensure safety for further clinical investigations in horses with increased bone resorption processes.     

Faecal calcium excretion does not decrease during long‐term feeding of a low‐calcium diet in adult dogs

According to a previous meta‐analysis, adult dogs do not notably increase calcium absorption from the gastrointestinal tract when calcium intake is decreased. This results in a negative calcium balance even with a moderate calcium reduction. In this study we wanted to verify (i) whether a negative calcium balance occurs at a calcium intake equivalent to NRC (2006) (Nutrient requirements of dogs and cats, 2006, The National Academies Press, Washington, DC) minimal requirements, and if so (ii) whether the negative calcium balance will persist for up to 6 months on a low‐calcium diet. After a pre‐feeding period of at least 18 weeks with calcium intake slightly exceeding maintenance requirements (200 mg/kg body weight^0.75), 12 dogs (6 Beagles, 6 Foxhound crossbreds) were fed a low‐calcium diet for 28 weeks. One dog was removed from the trial for reasons unrelated to the study at week 23. Calcium intake amounted to 60 mg/kg body weight^0.75 corresponding to the minimal requirement for maintenance in dogs (NRC, 2006 (Nutrient requirements of dogs and cats, 2006, The National Academies Press, Washington, DC)). Digestion trials were carried out at week 7, 14, 21 and 28 of the low calcium feeding period. At these time points, and at week 18 of the pre‐trial, blood samples were taken and analysed for calcium, ionised calcium, phosphorus, parathyroid hormone, vitamin D, serum crosslaps and bone alkaline phosphatase. Apparent calcium digestibility was negative throughout the study, suggesting a negative calcium balance. There was no systematic decrease in faecal calcium excretion. Serum calcium, ionised calcium and phosphorus remained within the reference range. Serum crosslaps increased continuously from baseline to week 28 of trial, with averages increasing from 0.102 ng/ml to 0.279 ng/ml, suggesting osteoclastic activity, indicative of calcium mobilisation from the skeleton. The study supports the theory of a lack of adaptation of intestinal calcium absorption from diets with relatively low calcium content in dogs. This agrees with clinical findings in dogs eating low‐calcium diet.     

Mineral metabolism in healthy geriatric dogs

To study mineral metabolism in geriatric dogs, parathyroid hormone, calcitriol, ionised calcium, phosphorus, blood urea nitrogen and creatinine were evaluated in 35 geriatric dogs (> 10 years) and in 20 young adult dogs (2–5 years). Parathyroid hormone levels were within the normal range in both groups, but values (mean ± SEM) were greater in the old dogs (34·8 ± 3·6 vs 21·2 ± 2·3 pg ml⁻¹, P=0·005). Calcitriol and ionised calcium were similar in the two groups, and the values for both parameters were within the normal reference range. Plasma phosphorus levels were in the normal range in both groups but tended to be greater in the older dogs (P=0·09). While blood urea nitrogen was similar in the two groups, creatinine levels (mean ± SEM) were higher in the young dogs (82·2 ± 3·5 vs 101 ·7 ± 4·4 μmol litre⁻¹). Even when the dogs were matched for weight, plasma creatinine concentration was still greater in the younger dogs. In conclusion, an increase in parathyroid hormone without changes in calcium, phosphorus and calcitriol has been identified in geriatric dogs.     

Hyperparathyroid disorders in the dog: primary, secondary and cancer-associated (pseudo)

Hyperparathyroid disorders were diagnosed in four dogs: one had primary hyperparathyroidism, characterized by parathyroid adenoma and hyper-calcaemia; one had renal secondary hyperparathyroidism, characterized by parathyroid gland hyperplasia, hypocalcaemia and renal failure; and two had cancer-associated hyperparathyroidism (pseudohyperpara-thyroidism), characterized by the presence of neoplasia, parathyroid gland atrophy, hypercalcaemia and absence of skeletal metastases. Significant clinicopathologic findings included serum concentrations of calcium, phosphorus and immunoreactive parathyroid hormone (PTH), presence or absence of parathyroid and bone lesions, and the presence of non-parathyroid neoplasia.     

Fanconi's Syndrome in a Dog With Primary Hypoparathyroidism

An 11 -year-old castrated male mixed breed dog was referred for evaluation of muscle twitching, polyuria, polydipsia, anorexia, and periocular alopecia. Primary hypoparathyroidism was diagnosed by documenting decreased serum concentrations of parathyroid hormone and ionized calcium. Neurological, gastrointestinal, and dermatological signs resolved after calcium repletion. Initially, 1,25-dihydroxycholecalcif erol PO was required to correct the hypocalcemia. Dihydrotachysterol, in combination with oral calcium supplementation, was used for long-term maintenance of normal serum calcium concentration. Aminoaciduria, glucosuria, and hyperchloremic metabolic acidosis were consistent with a diagnosis of Fanconi's syndrome. This diagnosis was further supported by the presence of hypokalemia and increased urinary fractional excretion of sodium, potassium, calcium, phosphorus, and magnesium. Renal tubular dysfunction resolved after oral supplementation with calcium and vitamin D₃. Fanconi's syndrome in this dog may have been caused by decreased serum concentration of 1,25-dihydroxycholecalciferol, which was secondary to decreased parathyroid hormone production.     

Effects of large granular lymphocyte leukemia on bone in F344 rats

Large granular lymphocyte (LGL) leukemia was induced in 40 F344 rats by inoculating them with neoplastic cells to evaluate the effect of acute leukemia on bone remodeling and calcium balance. The rats developed leukemia and splenomegaly by 9 days after inoculation. The rats had reduced body weight (day 12), food intake (days 4, 8, 12), urine production (day 12), and fecal output (day 12). Serum calcium and phosphorus and urinary excretion of calcium and phosphorus were decreased on days 8 and 12 in leukemic rats. Static bone histomorphometry of trabecular bone in lumbar vertebrae demonstrated reduced bone area, no change in the number of osteoclasts, and reduced osteoclast perimeter at day 12. Dynamic bone histomorphometry revealed reduced double labeled perimeter, mineralizing perimeter, trabecular mineral appositional rate, and bone formation rate in rats with LGL leukemia at days 9 and 12. There was no change in periosteal mineral appositional rate. Rats with leukemia and intramedullary neoplastic cells had a reduction in bone formation rate that resulted in a loss of trabecular bone.     

骨代谢相关血液生化指标的研究进展

骨代谢包括骨合成和骨吸收两个过程。受到很多因素的影响,遗传、营养、环境、性别及内分泌等都是关键调节因素。当骨吸收过程大于骨合成过程,导致骨量流失,骨密度降低,进一步发展为骨质疏松症。骨代谢过程受到内分泌的影响,很多骨代谢血液生化指标对骨病的研究起到重要作用。近年来,国内外大量的研究报道了与骨代谢相关的血液生化指标。作者着重对血钙与血磷、甲状旁腺激素、1,25-二羟维生素D₃、白细胞介素、血清总碱磷酶和骨碱磷酶等骨代谢血液生化指标对骨形成和分解的影响进行了综述。     

Clinical and metabolic findings in dogs with chronic renal failure fed two diets.

Exogenous creatinine clearance, urinary electrolyte excretions, calcium and phosphorus balance, serum cholesterol concentration, arterial blood pressure, and body weight were evaluated in dogs with chronic renal failure that were fed 2 commercial diets. Nine dogs ranging in age from 1 to 15 years were identified as having mild to moderate chronic renal failure (CRF, exogenous creatinine clearance = 0.5 to 2.13 ml/kg of body weight/min). These dogs and a group of 10 clinically normal controls were fed a diet containing 31% protein for 8 weeks at which time hematologic and biochemical evaluations and clearance studies were performed. All dogs then were fed a phosphorus-restricted diet containing 16% protein and then reevaluated after 8 weeks. The dogs in this study had hematologic and biochemical abnormalities typical of CRF. Urine absolute and fractional excretion of electrolytes was higher in dogs with CRF than in controls and was affected by diet. Serum cholesterol concentration was higher in dogs with CRF and increased in those dogs after feeding the low protein diet. Changes in dietary sodium intake did not affect arterial blood pressure. The phosphorus-restricted diet did not affect serum amino terminal parathyroid hormone concentration in either group. Control dogs lost body weight, whereas dogs with CRF gained weight when fed the low protein diet. We concluded that dogs with mild to moderately severe CRF have the same biochemical abnormalities and response to dietary restriction of protein and phosphorus as has been previously reported in dogs with experimentally induced CRF. Restriction of dietary sodium may not decrease arterial blood pressure in some dogs with CRF.(ABSTRACT TRUNCATED AT 250 WORDS)