The cervical vertebral column of horses--a clinico-radiological study

For various anamnestic reasons the cervical vertebral column of 78 horses was examined radiologically. Statistical comparisons showed that male "warmbloods" were more frequently affected than was expected. Our horses were older than comparable animals in the international literature. Independently of their history the radiologic diagnosis of "cervical spondylarthrosis" was established in 56 horses. Arthrosis and other conditions were clinically manifested by spinal ataxia (44 horses) or mechanical impairment of the neck's mobility (21 horses). 10 of the arthrotic patients had synovial cysts causing compression of the spinal cord. 79 percent of all dorsal intervertebral arthrotic joints were found in the caudal column (C6/7 to C7/Th1). With 38 percent, C6/7 was the most frequently affected joint. Clinical and radiological findings could be compared with patho-anatomic results in 29 horses. The correlation was satisfactory.     

Implications of using an average relationship matrix in genetic evaluation for a population using multiple-sire matings

SUMMARY: Ambiguous paternity can be incorporated into the mixed model equations (MME) by including the average numerator relatinship matrix (average A), which averages the true sire-offspring relationship over the putative sires. A previous study has shown that some overestimation of genetic trend results from this substitution. A population of 40 breeding females and 2 breeding males was simulated 1,000 times with either random mating or sequential selection continuing for 8 breeding cycles. In the selection case candidates were ranked on estimated breeding values (EBVs) calculated from the MME with an animal model and the average A. Variances of the EBVs and prediction errors were computed. The results showed the average A incorrectly perceives both the variance of family sizes among males and the variance loss due to selection to be smaller. This will lead to an overestimation of genetic trend. ZUSAMMENFASSUNG: Folgerungen aus der Anwendung einer durchschnittlichen Verwandtschaftsmatrix bei der Zuchtwertsch?tzung für eine Population mit mehreren V?tern in einer Paarungsgruppe In den Mischmodellgleichungen kann eine unklare v?terliche Abstammung durch die Verwendung einer durchschnittlichen Verwandtschaftsmatrix, die die Abstammung zu gleichen Teilen über die m?glichen V?ter aufteilt, berücksichtigt werden. Eine frühere Arbeit hat gezeigt, da? diese Ma?nahme zu einer gewissen übersch?tzung des genetischen Fortschritts führt. Eine Population mit 40 weiblichen und 2 m?nnlichen Tieren wurde 1000mal über 8 Paarungsperioden simuliert und zwar mit und ohne gerichteter Selektion. Im Falle der Selektion wurden die Tiere aufgrund der mit einem Tiermodell und der durchschnittlichen Verwandtschaftsmatrix gesch?tzten Zuchtwerte geordnet. Die Varianzen der Zuchtwerte und der Sch?tzfehler wurden berechnet. Die Ergebnisse zeigen, da? durch eine durch-schnittliche Verwandtschaftsmatrix die Varianz der Gr??e der Nachkommensgruppen der V?ter und der Verlust an genetischer Varianz aufgrund der Selektion untersch?tzt wird. Dies führt zu einer übersch?tzung des genetischen Fortschritts.     

Polioencephalomalacia in cattle consuming water with elevated sodium sulfate levels: A herd investigation

Polioencephalomalacia (PEM), hereafter used to refer to the specific lesion of cerebrocortical necrosis, developed in 11 of 110 mature cattle on pasture in central Saskatchewan. The primary water source contained a markedly elevated level of sodium sulfate (7200 ppm). The significant clinical findings of the herd investigation included depression, ataxia, cortical blindness, dysphagia, and death. Diagnosis of PEM was confirmed by histopathological evidence of cerebrocortical and subcortical necrosis with microvascular fibrinoid necrosis predominantly in the thalamic region of three affected cattle. The histopathology of sulfate-associated PEM observed in this herd appears to be unique and its features are presented and discussed. Mean levels for serum transketolase, copper, red blood cell transketolase activity, and thiamine (vitamin B₁) in all exposed young (n = 100) and mature (n = 99) animals did not reveal evidence of deficiencies. Although the blood thiamine status of the seven surviving, affected animals was not evaluated before treatment with exogenous thiamine, 199 members of the herd had blood thiamine levels within the reference range at the time of the outbreak. The outbreak resolved after cattle were moved to a water source containing acceptable levels of sodium sulfate.