Variability in concentrations of zinc in serum and feed when using zinc oxide as a supplement for the prevention of facial eczema

AIMS: To determine the variability of concentrations of Zn in feed, when used as a supplement to prevent facial eczema, and to determine the variability in concentrations of Zn in serum between cows and herds that are being supplemented with ZnO in feed, using in-shed feeders or on a feed pad.

METHODS: Sixteen commercial dairy farms in the Waikato region of New Zealand were enrolled, that were supplementing cows with ZnO in the feed using either an automatic in-shed feeder (ASF) or a feed pad (FP) using a feed-out or mixer wagon. On each farm 10 cows were selected by the farmer, that were assumed to be representative of the age and liveweight of the herd. Four hours after supplement feeding, each cow was weighed and a blood sample collected for measurement of concentrations of Zn in serum. Three samples of feed were collected from each farm for Zn analysis, from the beginning, middle and end of the feed being distributed. Levene’s test for homoscedasticity was used to analyse whether there were differences in variation of individual concentrations of Zn in serum, and in the feed, between the two feeding systems. Multivariable linear regression was used to examine associations between age, feeding method or liveweight and concentrations of Zn in serum, after accounting for the variability between farms.

RESULTS: Of the 163 cows sampled, concentrations of Zn in serum were between 20–35?µmol/L in 75/163 (46 (95% CI=38–54)%) cows; were <20?µmol/L in 71/163 (44 (95% CI=36–52)%) cows, and >35?µmol/L in 17/163 (10 (95% CI=6–16)%) cows. The variation in concentrations of Zn in serum in individual cows differed between farms (p<0.001), and the variability was greater for cows fed using a FP than ASF (p<0.001). There was no difference in the variation of concentrations of Zn in feed between the two feeding methods (p=0.54), but concentrations of Zn in serum were associated with the amount of Zn offered in feed (p=0.008).

CONCLUSIONS AND CLINICIAL RELEVENCE: There was significant variability between farms in the concentrations of Zn in the serum of cows being supplemented with ZnO in feed. Only 46% of cows sampled had concentrations of Zn between 20–35?µmol/L. Effective management of facial eczema should include monitoring Zn in the feed and in serum to ensure cows are receiving the correct dose they require.     

Cutaneous metastases of a mammary carcinoma in a llama

An 8-year-old, female llama was evaluated for nonhealing, ulcerative, cutaneous lesions, which also involved the mammary gland. Biopsies of the lesions distant from and within the mammary gland area revealed an aggressive carcinoma. The tumor was confirmed at necropsy to be a mammary gland adenocarcinoma with cutaneous metastasis.     

Radiculomeningomyelitis due to Halicephalobus gingivalis in a horse

An adult horse was euthanatized following a clinical diagnosis of cauda equina neuritis. Significant gross postmortem and histopathologic findings were limited to the sacral spinal cord and cauda equina. The sacral spinal cord, meninges, and spinal nerve roots were expanded and partially effaced by sclerosing granulomatous inflammation with necrosis. The lesion contained numerous nematode larvae and fewer adults with a rhabditiform esophagus having a corpus, isthmus, and valved bulb. Female nematodes were amphidelphic and didelphic with reflexed ovaries. These morphologic features confirm Halicephalobus gingivalis as a novel cause of clinical signs in this case of cauda equina neuritis.     

Time-dependent changes in plasma concentrations of 3-methylindole and blood concentrations of 3-methyleneindolenine-adduct in feedlot cattle

OBJECTIVE: To describe time-dependent changes in plasma concentrations of 3-methylindole (3MI) and blood concentrations of 3-methyleneindolenine (3MEIN)-adduct in feedlot cattle. ANIMALS: 64 yearling steers. PROCEDURES: Steers were assigned to 2 groups (32 steers/group). During the first 8 weeks, blood samples were collected from group 1 before the morning ration was fed, whereas samples from group 2 were collected 2 to 3 hours after the ration was fed. Blood samples were collected from all steers approximately 4 times/wk for 3 weeks and 3 times/wk for the subsequent 5 weeks. Samples were collected at the same time for all steers for an additional 10 weeks. Plasma samples were analyzed for 3MI concentrations. Blood samples collected from cattle in group 2 during the first 8 weeks were analyzed for 3MEIN-adduct concentrations. RESULTS: Mean blood concentration of 3MEIN-adduct increased to a maximum value on day 33 (0.80 U/microg of protein) and then decreased to a minimum on day 54 0.40 U/microg of protein). Plasma 3MI concentrations initially decreased and remained low until after day 54. Group-1 cattle had lower plasma 3MI concentrations, compared with concentrations for group-2 cattle. Blood 3MEIN-adduct concentrations and plasma 3MI concentrations were not associated with deleterious effects on weight gains. CONCLUSIONS AND CLINICAL RELEVANCE: Blood 3MEIN-adduct concentrations peaked during the period of greatest risk for development of bovine respiratory disease complex. Conversely, plasma 3MI concentrations decreased during the same period. Animal-to-animal variation in metabolic capacity to convert 3MI to 3MEIN may be of more importance than differences in plasma 3MI concentration.     

Effect of background serum lithium concentrations on the accuracy of lithium dilution cardiac output determination in dogs

OBJECTIVES: To assess the effect of increasing serum lithium concentrations on lithium dilution cardiac output (LiDCO) determination and to determine the ability to predict the serum lithium concentration from the cumulative lithium chloride dosage. ANIMALS: 10 dogs (7 males, 3 females). PROCEDURE: Cardiac output (CO) was determined in anesthetized dogs by measuring LiDCO and thermodilution cardiac output (TDCO). The effect of the serum lithium concentration on LiDCO was assessed by observing the agreement between TDCO and LiDCO at various serum lithium concentrations. Also, cumulative lithium chloride dosage was compared with the corresponding serum lithium concentrations. RESULTS: 44 paired observations were used. The linear regression analysis for the effect of the serum lithium concentration on the agreement between TDCO and LiDCO revealed a slope of -1.530 (95% confidence interval [CI], -2.388 to -0.671) and a y-intercept of 0.011 (r2 = 0.235). The linear regression analysis for the effect of the cumulative lithium chloride dosage on the serum lithium concentration revealed a slope of 2.291 (95% CI, 2.153 to 2.429) and a y-intercept of 0.008 (r2 = 0.969). CONCLUSIONS AND CLINICAL RELEVANCE: The LiDCO measurement increased slightly as the serum lithium concentration increased. This error was not clinically relevant and was minimal at a serum lithium concentration of 0.1 mmol/L and modest at a concentration of 0.4 mmol/L. The serum lithium concentration can be reliably predicted from the cumulative lithium dosage if lithium chloride is administered often within a short period.     

In vitro biomechanical study of rotational stabilizers of the canine elbow joint

OBJECTIVE: To develop a model for measuring rotary stability of the canine elbow joint and to evaluate the relative contribution of the anconeal process (AN), lateral collateral ligament (LCL), and medial collateral ligament (MCL). SAMPLE POPULATION: 18 forelimbs from 12 canine cadavers. PROCEDURE: Forelimbs were allocated to 3 experimental groups (6 forelimbs/group). Each intact forelimb was placed in extension at an angle of 135 degrees and cycled 50 times from -16 degrees (pronation) to +28 degrees (supination) in a continuous manner at 2.0 Hz. Cycling was repeated following sectioning of the structure of interest (group 1, AN; group 2, LCL; and group 3, MCL). Torque at -12 degrees (pronation) and +18 degrees (supination) was measured for each intact and experimentally sectioned limb. A Student t test was performed to compare torque values obtained from intact verses experimentally sectioned limbs and for comparison with established criteria for differentiation of primary (> or = 33%), secondary (10 to 33%), and tertiary rotational stabilizers (< 10%). RESULTS: In pronation, the AN was the only primary stabilizer (65%). For supination, the LCL was a primary stabilizer (48%), AN was a secondary stabilizer (24%), and MCL was a tertiary stabilizer (7%). CONCLUSIONS AND CLINICAL RELEVANCE: With the elbow joint in extension at an angle of 135 degrees, the AN is a primary rotational stabilizer in pronation, and the LCL is a primary stabilizer in supination. Disruption of the AN or LCL may affect rotary range of motion or compromise stability of the elbow joint in dogs.     

Performing the field necropsy examination.

This article is designed to aid the practitioner by maximizing the effectiveness of field postmortem diagnostic investigations. Contents include an outline of the procedure for field necropsy of ruminants, recommended tools and supplies, and guidelines for sample collection and submission.     

A Combination Chemotherapy Protocol (VELCAP-L) for Dogs with Lymphoma

Ninety-eight dogs with lymphoma treated with a 5-drug combination chemotherapy regimen (vincristine, L-asparaginase. cyclophosphamide, doxorubicin, prednisone [VELCAP-L]) were evaluated for pretreatment characteristics predictive for response and remission duration. The complete remission rate was 69%, with a median remission duration of 55 weeks. Dogs with advanced stage of disease, constitutional signs, dogs that were older, and dogs that were dyspneic were less likely to achieve remission. Once in remission, small dogs and dogs without pretreatment thrombocytopenia were likely to have longer remission duration. Toxicoses were frequent, but rarely fatal, and no predictitive factors were found for a dog developing toxicoses. VELCAP-L is an effective treatment for dogs in stage I-III lymphoma, particularly in young, small animals.