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dependent on the dog's pulmonary physiology and the partial pressure of oxygen in the atmospheric air (P b ). With an increase in altitude and concurrent drop in barometric pressure, the number of gas molecules in the atmosphere decreases; therefore, each
The Qinghai-Tibetan Plateau is the highest and biggest plateau in the world, with an area of 2.5 million km 2 and a mean altitude > 4,500 m. The flora and fauna on the plateau are constantly exposed to a harsh environment with a low percentage of
at sea level and at a high altitude in a racing jurisdiction that did not permit administration of furosemide nor use of nasal dilator strips on race day. Materials and Methods Animals —Thoroughbreds of either sex that raced on turf or sand on
Summary
We investigated the biochemical composition of blood from Holstein cows, native breed (criollas), and cows descended from fighting bulls (Vacas de lidia) raised at an altitude of 3,000 m (moderately high altitude, mha), and compared the results with those from Holsteins and cows of similar genetic ancestry as the criollas (scrub cows), both raised at sea level (sl), to determine blood biochemical values characteristic of adaptation to high altitude. Only potassium and calcium concentrations were similar among groups. Glucose concentration was lower in mha cows, with the exception of Vacas de lidia. Serum bicarbonate concentration was lower in mha cows; this finding can be explained by hyperventilation in the hypoxic environment. Serum magnesium concentration was lower in sl and mha Holsteins than in other groups. Serum phosphate concentration was lower in scrub cows, mha Holsteins, and criollas than in other groups. Cholesterol concentrations were lower in sl Holsteins, whereas triglycerides were higher in scrub cows and mha Vacas de lidia. Concentration of high-density lipoprotein was significantly greater in Vacas de lidia and less in mha criollas than in the other groups. Uric acid and total protein were higher in mha groups. Using radioimmunoassay for human proteins, thyroxine-binding globulin was undetectable. Total and free thyroxine and free triiodothyronine were higher in scrub cows, followed by Vacas de lidia; lower values were detected in sl and mha Holsteins and mha criollas.
Summary
Gene frequencies of rbc antigens were determined in Holsteins and Colombian (criollas) cattle living at 3,000 m, and in cattle descended from fighting bulls (Vacas de lidia) living at 2,500 m. These frequencies were compared with those of Holsteins, cattle native to Florida (scrub cattle), longhorns, and native cattle from Brazil (caracu cattle) living at sea level. The criollas, Vacas de lidia, scrub cows, longhorns, and caracu are descendants of original Iberian stock introduced to the Americas. We found that despite common ancestry (scrub cattle, longhorns, criollas, and caracu), genetic differences may have been derived through years of demographic isolation. The most remarkable blood-group differences were found in the high prevalence of the B system phenogroup (heritable group of antigenic factors) BQA'G'34 in the Vacas de lidia, and of the S system phenogroup U1H' in these cattle and in caracu. Furthermore, the gene frequencies differed in the Holsteins maintained at moderately high altitude (descended from Holsteins kept at sea level), and may have been reflective of the need to adapt to moderately high altitude and chronic hypoxemic conditions. Blood group polymorphism was found in all groups of cattle, although it was reduced in the Vacas de lidia, possibly because their breeding has been carefully controlled and they appear to be highly inbred.
Summary
Proportional hospital accession ratios for chronic superficial keratitis (csk) of dogs were determined for 16 US veterinary teaching hospitals participating in the Veterinary Medical Data Base between Jan 1, 1976 and Dec 31, 1991. The prevalence of csk was significantly correlated (r = 0.90) with altitude of residence, but not with latitude, longitude, mean annual solar radiation, or mean annual relative humidity.
Medical records of dogs with (n = 595) and without (n = 72,877) csk examined at the Colorado State University Veterinary Teaching Hospital between Jan 1, 1976 and Oct 28, 1991 were also reviewed. Belgian Tervuren, German Shepherd Dogs, Border Collies, Greyhounds, Siberian Huskies, and Australian Shepherds were disproportionately affected. Dogs between 4 and 7 years old were 2.36 times more likely to develop lesions than were dogs < 4 years old (P < 0.05). Among dogs < 4 years old, spayed females, sexually intact males, and castrated males were more likely to develop the condition (P < 0.05) than were sexually intact females. Altitude of residence was a significant risk factor in the development of csk among dogs in Colorado. Dogs living at altitudes > 7,000 ft above sea level were 7.75 times more likely to develop lesions than were dogs living at elevations between 3,000 and 5,000 ft.
Abstract
Objective—To evaluate herd-level risk factors for seropositive status of cattle to 1 or more bluetongue viruses.
Animals—110 herds of cattle in Nebraska, North Dakota, and South Dakota.
Procedure—Blood samples were collected before and after the vector season. Samples were tested for antibodies against bluetongue virus by use of a commercially available competitive ELISA. Factors evaluated included descriptors of geographic location and management practices. Trapping of insect vectors was conducted to evaluate vector status on a subset of 57 operations. A multivariable logistic regression model was constructed to evaluate associations.
Results—For the full data set, altitude and latitude were associated with risk of having seropositive cattle (an increase in altitude was associated with an increase in risk, and a more northerly location was associated with a decrease in risk of a premise having seropositive cattle). Import of cattle from selected states was associated with an increase in risk of having seropositive cattle. From the subset of herds with data on vector trapping, altitude and latitude were associated with risk of having seropositive cattle, similar to that for the full model. However, commingling with cattle from other herds was associated with a decrease in risk of seropositivity.
Conclusions and Clinical Relevance—Findings reported here may be useful in generating additional hypotheses regarding the ecologic characteristics of bluetongue viruses and other vector-borne diseases of livestock. Sentinel surveillance programs are useful for documenting regionalization zones for diseases, which can be beneficial when securing international markets for animals and animal products. (Am J Vet Res 2005;66:853–860)
Abstract
Objective—To assess effects of high dietary amounts of vitamin C or vitamin E and oxidative stress on the heart and growth performance of broilers maintained at an altitude of 2,200 m above sea level.
Animals—360 chicks (1-day-old broilers).
Procedure—Birds were randomly assigned to 3 groups (120 chicks/group). Each group of birds was fed a specific diet (control group, basal diet containing 12 mg of vitamin E (DL-α-tocopherol acetate)/kg of feed without additional ascorbic acid; vitamin E group, basal diet supplemented with 75 mg of vitamin E/kg of feed; and vitamin C group, basal diet supplemented with 400 mg of ascorbic acid/kg of feed) throughout the entire 7 weeks of the study. Feed consumption and body weight of chicks were recorded on a weekly basis. Nine randomly selected birds from each group were euthanatized each week. Remaining birds were euthanatized at the end of the study. Samples of cardiac tissues were obtained to measure thiobarbituric acid reactive substances (TBARS), an indicator of oxidative stress.
Results—Vitamin E-supplemented diets resulted in better growth performance, lower rates of feed conversion, and lower TBARS content. Vitamin C-supplemented diets resulted in lower feed consumption and lower rates of feed conversion. When used separately, neither of the vitamins had any effect on mortality attributable to ascites syndrome.
Conclusions and Clinical Relevance—It is recommended that diets supplemented with vitamin C, vitamin E, or both be fed to broilers maintained at an altitude of 2,200 m above sea level to improve growth performance. (Am J Vet Res 2002;63:673–676)
SUMMARY
The association between ocular squamous cell tumors and various measures of solar radiation was evaluated for 2,775 contemporaneous Hereford cattle. The animals were from 34 herds located in 21 states in the United States and in one Canadian province. Examinations and photographs were made of the eyes of all cows and heifers in a herd; 33 herds were examined between June and August 1957 and 1 herd was examined in 1958. Solar radiation was measured by altitude and mean annual hours of sunshine applying to an individual herd, and global radiation, a cloudiness index, and elevation of nearby National Weather Service stations. All measures of solar radiation provided evidence of a significant association between increasing risks of developing cancer eye and increasing levels of radiation; adjustments were made for possible confounding effects of age and corneoscleral pigmentation. Associations were evident whether affliction was defined as the occurrence of any type of tumor (ie, plaque, papilloma, or carcinoma), or as the occurrence of only papilloma or carcinoma. Average ages of affected cattle also tended to be lower at high radiation levels than at low levels, further supporting the hypothesis that solar radiation has an important role in the development of this disease. In view of the heritability of eye pigmentation and its inhibitory effect on lesions, cancer eye may be controlled by selective breeding for increased pigmentation in and around the eye to afford protection against the harmful effects of incident uv radiation.
Summary
Proportional hospital accession ratios for equine ocular/adnexal squamous cell carcinoma (scc) were determined for 14 colleges of veterinary medicine participating in the Veterinary Medical Data Program between January 1978 and December 1986. Comparison of the ratios with their respective geographical, physical data has shown an increased prevalence of scc with an increase in longitude, altitude, or mean annual solar radiation. In contrast, prevalence of scc increased with a decrease in latitude.
Between January 1978 and December 1988, 147 horses with ocular/adnexal scc were admitted to the Colorado State University Veterinary Teaching Hospital. Diagnosis was confirmed by histologic examination of appropriate tissue specimens. Medical records provided information regarding month and year of admission and diagnosis, age at diagnosis, breed, gender, and hair color. Comparison with a randomly selected hospital control population revealed an increased prevalence of ocular/adnexal scc with an increase in age (P < 0.001). Compared with Quarter Horses, draft breeds (Belgian, Clydesdale, and Shire) and Appaloosas had a significantly (P < 0.001) greater prevalence of ocular/adnexal scc. Sexually intact males and females were significantly (P < 0.001) less likely (5 and 2 times, respectively) to have ocular/adnexal scc when compared with castrated males. The prevalence of ocular/adnexal scc was significantly greater for all hair colors when compared with bay, brown, or black (P < 0.01).
