Congenital nutritional myodegeneration (white muscle disease) in a red deer (Cervus elaphus) calf

CASE HISTORY A 5-day-old red deer calf was submitted with tachypnoea and dyspnoea, and was reluctant to move.

CLINICAL FINDINGS: Muscular damage was established via elevated creatinine phosphokinase (CPK) activities (5,000 U/L), while concentrations of Se in whole blood were low (24.8 nmol/L). The animal died despite treatment with penicillin-streptomycin and 0.1 mg/kg Se/vitamin E administered by S/C injection.

DIAGNOSIS: Necropsy and histological examination of cardiac and skeletal muscle confirmed the presumptive diagnosis of congenital white muscle disease (WMD). Prophylactic administration of a Se/vitamin E commercial preparation (as above) to another calf born in the same herd one month later was associated with good health and apparently normal growth and development.

CLINICAL RELEVANCE: Congenital WMD due to Se deficiency can be fatal in red deer calves. However, prophylactic administration of Se and vitamin E to neonatal calves may be beneficial for neonatal red deer calves.     

Loss of reserves of Cu in liver when Cu supplements are withdrawn from dairy herds in the Waikato region

Abstract

AIM: To monitor the consequences of withdrawing mineral Cu supplements from two dairy herds with initially high concentrations of Cu in liver.

METHODS: Two herds were selected from dairy farms in the Waikato region of New Zealand that participated in an earlier survey of Cu supplementation practices and Cu status of dairy cows. The herds were fed pasture, grass and maize silage, plus palm kernel expeller (PKE) containing 25–30 mg Cu/kg dry matter (DM) fed at 2–4 kg/cow/day. No mineral Cu supplements were supplied from January 2009. Pasture samples were collected for mineral analysis in September 2008 and April 2009. Concentration of Cu in liver biopsies from the same 9–10 cows per herd was measured on three occasions between April 2009 and May 2010.

RESULTS: Pastures on both farms contained 10 mg Cu/kg DM, 0.1–0.5 mg Mo/kg DM and 3.5–4.0 g S/kg DM. The initial herd mean concentrations of Cu in liver were 1,500 (SD 590) and 1,250 (SD 640) μmol Cu/kg fresh tissue. In the absence of mineral Cu supplements, those mean concentrations decreased over 12 months to 705 (SD 370) and 1,120 (SD 560) μmol Cu/kg fresh tissue, respectively. For cows in the first herd, the rate of depletion of liver Cu reserves was influenced by initial concentration of Cu, such that high concentration led to faster loss according to first-order kinetics.

CONCLUSIONS: Mineral Cu supplementation was not necessary over 12 months for two dairy herds with mean concentrations of Cu in liver >1,250 μmol Cu/kg fresh tissue, grazing pastures containing 10 mg Cu/kg DM and concentrations of Mo <1 mg/kg DM. The quantity and particularly the duration of feeding PKE appeared to be a factor in whether or not the herd lost substantial reserves of Cu in liver during the year. However, the Cu status of both herds in this study was more than adequate to support late pregnancy and mating.

CLINICAL REVELANCE: Copper status of the herd should be monitored and on-farm management of Cu nutrition should take into account all sources contributing to daily intake of Cu. Where Cu supplementation has been excessive and there is risk of chronic Cu toxicity, mineral Cu supplements may be withdrawn for a period commensurate with the expected rate of liver Cu depletion.     

Growth response to increasing doses of microencapsulated vitamin B12 and related changes in tissue vitamin B12 concentrations in cobalt-de cient lambs

AIM: To investigate growth responses of cobalt-deficient lambs to increasing doses of microencapsulated vitamin B₁₂, and to measure associated changes in serum and liver vitamin B₁₂ concentrations over 243 days.

METHODS: From a flock grazing pastures that had low cobalt (Co) levels (about 0.06 mg Co/kg dry matter), 4-6-week-old lambs (n=137) were assigned to four groups and received either no treatment or a subcutaneous injection of 3.0, 4.5 or 6.0 mg of microencapsulated vitamin B₁₂ on Day 1. At approximately monthly intervals, all lambs were weighed and blood samples were collected from a selection (n=10) of monitor animals, up to Day 243. Liver biopsies were also carried out on the monitor lambs (n=8) on Days 1, 124 and 215.

RESULTS: The vitamin B₁₂-treated lambs grew significantly faster (p<0.001) than untreated animals. Liveweights after 243 days were 28, 45, 45 and 47 kg for the untreated, 3.0, 4.5 and 6.0 mg vitamin B₁₂-treated lambs, respectively. Of the initial group of untreated lambs, 68% had to be removed before the end of the trial because of substantial weight loss, but none of the treated animals were similarly afflicted. Serum vitamin B₁₂ concentrations increased in all vitamin B₁₂-treated lambs, reaching a peak at Day 25, and those of the 4.5 and 6.0 mg vitamin B₁₂-treated lambs remained significantly higher (except at Day 124) than the untreated lambs to Day 187. However, at Day 124, but not Day 215, the liver vitamin B₁₂ concentrations of treated lambs were two to three times higher than those of controls.

CONCLUSIONS: The growth rates of Co-deficient lambs were markedly improved by injection of 3.0, 4.5 or 6.0 mg of microencapsulated vitamin B₁₂, and liveweights were maintained for at least 243 days. Serum vitamin B₁₂ concentrations were related to this growth response; concentrations of <220 pmol vitamin B₁₂/l were associated with a 95% probability that lambs were Co-deficient and would thus respond to Co/vitamin B₁₂ supplementation. Based on these data, the current New Zealand reference criteria for Co deficiency should be reviewed.

CLINICAL SIGNIFICANCE: An injection of 3 mg microencapsulated vitamin B₁₂2 given to lambs at tailing will treat Co deficiency and will increase and maintain liveweights in a flock for up to 8 months.     

A practical approach to managing the risks of iodine deficiency in flocks using thyroid-weight:birthweight ratios of lambs

AIM: To establish a protocol for determining the iodine status of a flock and managing the risks of iodine deficiency, using thyroid-weight:birthweight ratios of newborn lambs and serum iodine concentrations of ewes.

METHODS: Data were collected from iodine supplementation studies in Southland and Rangitikei, of sheep fed exclusively pasture or pasture plus brassica during the latter half of gestation (n=350, or 89 per treatment group). The ewes were supplemented pre-mating or at the time of pregnancy scanning with an injection of long-acting iodised oil. Serum iodine concentrations were measured in ewes prepartum in Rangitikei and postpartum at both locations. The thyroid-weight:birthweight ratios (as g/kg) in 229 newborn lambs were determined at post-mortem examination and compared between iodine supplemented vs unsupplemented flocks using probit analysis. Samples of pasture and kale were analysed monthly for determination of iodine and selenium.

RESULTS: Initial mean serum iodine concentration of all ewes was 41 µg iodine/L. Supplementation increased serum iodine concentrations regardless of forage fed, and concentrations remained high for between 127 and 206 days. The range of thyroid-weight:birthweight ratios in lambs from supplemented ewes was 0.09–0.70 (mean 0.35, standard deviation (SD) 0.147) g/kg. Among lambs from unsupplemented ewes, the range was much wider (0.21–8.5; mean 1.61, SD 1.95 g/kg). About half of those ratios were >0.8 g/kg and clearly indicative of goitre, including 62% from the groups on brassica and 18% from the Rangitikei group fed exclusively pasture. Probit calculations showed that a ratio of 0.40 (95% confidence interval (CI)=0.29–0.47) g/kg predicted with 35% probability, and a ratio of 0.80 (95% CI=0.70–0.99) g/kg predicted with 90% probability that a lamb came from an unsupplemented flock.

CONCLUSIONS: Compared to iodine concentrations in forages, thyroid-weight:birthweight ratios more accurately reflected the iodine status of the flock and could be used to identify which flocks to supplement the following year. Serum iodine concentrations of ewes measured before or after lambing did not reflect forage fed, but values near 40 µg/L were associated with goitrous lambs.

CLINICAL RELEVANCE: Thyroid-weight:birthweight ratios >0.8 g/kg were indicative of iodine deficiency, and ewes should be supplemented pre-mating or during pregnancy to prevent goitre the following year. Ratios <0.4 g/kg rarely occurred among deficient flocks, so the probability of benefit from supplementation was low. Intermediate ratios were ambiguous, and the iodine status of the flock could not be determined from biomarkers. In such cases individual-farm supplementation trials might be required to detect and manage the risks of marginal deficiency.     

Age determination of eland Taurotragus oryx (Pallas, 1766) in the Natal Highveld

Techniques for the age determination of highveld eland in Natal were investigated. Tooth eruption and replacement sequence, and growth in horn length, were suitable criteria for the age determination of young eland with deciduous dentition. The most accurate technique for the age determination of post mortem adult eland was based on counts of cementum annuli from molar teeth. Animals without distinctive cementum annuli may be assigned ages from measurements of M₃ crown height. The ages of live restrained eland could be derived from measurements of I₁ occlusal width or I₁, crown height. Horn morphology was adequate for age and sex classification of free-ranging eland up to adult status.     

Evaluation of the respiratory elimination kinetics of selenium after oral administration in sheep

OBJECTIVE: To evaluate the respiratory excretion and elimination kinetics of organic and inorganic selenium after oral administration in sheep. ANIMALS: 38 crossbred sheep. PROCEDURES: Selenium was administered PO to sheep as a single dose of 0, 1, 2, 3, or 4 mg/kg as sodium selenite or selenomethionine. Expired air was collected and analyzed from all sheep at 4, 8, and 16 hours after administration. RESULTS: Clinical signs consistent with selenium intoxication were seen in treatment groups given sodium selenite but not in treatment groups given the equivalent amount of selenium as selenomethionine. However, a distinct garlic-like odor was evident in the breath of all sheep receiving 2 to 4 mg of selenium/kg. The intensity of odor in the breath did not correlate with clinical signs in affected animals receiving sodium selenite treatment. CONCLUSIONS AND CLINICAL RELEVANCE: The concentration of selenium in expired air was greater in sheep receiving selenium as selenomethionine than sodium selenite. The concentration of selenium in expired air from sheep receiving high doses of selenium (3 and 4 mg of selenium/kg) was larger and selenium was expired for a longer duration than the concentration of selenium in expired air from sheep receiving low doses of selenium (1 and 2 mg of selenium/kg).     

Spinal shock--comparative aspects and clinical relevance

Spinal shock is the loss of muscle tone and segmental spinal reflexes that develops caudal to a severe spinal cord injury. Although little recognized in the veterinary literature, spinal shock occurs in animals and is important in both accurate lesion localization and case management. In this review, we consider why spinal shock occurs and discuss the subsequent physiologic alterations, including the development of reflex hyperactivity. We also discuss differences in the expression of spinal shock between species and suggest why recovery of reflexes is relatively rapid in animals compared with humans. Finally, the implications for clinicians dealing with animals in the period immediately after severe spinal injury are considered.     

Biliary secretion of 14C and identification of 5,6-dihydro-5,6-dihydroxycarbaryl glucuronide as a biliary metabolite of [14C]carbaryl in the rat

The biliary secretion of ¹⁴C was observed in conscious, bile-fistulated rats given single oral doses of [¹⁴C]carbaryl (1.5, 30, and 300 mg/kg). Over 94% of the ¹⁴C was absorbed after 12 hr. From 15 to 46% of the ¹⁴C was secreted in bile, 10–40% in urine, and less than 1% in feces 12 hr after dosing. Three metabolites were isolated from bile and identified by mass and/or NMR spectrometric methods. These metabolites were: 5,6-dihydro-5,6-dihydroxycarbaryl glucuronide (12–18% of the biliary ¹⁴C), a conjugate(s) of carbaryl (12% of the biliary ¹⁴C), and conjugated isomers of hydroxy-carbaryl (2% of the biliary ¹⁴C). The majority of the biliary ¹⁴C remains to be identified.     

Internal fixation of femoral head and neck fractures in the cat

A quick surgical approach for internal reduction and fixation of femoral head and neck fractures is described. The results and reasons for preferring this technique to femoral head and neck excision are discussed.