Sarel R Van Amstel BVSc, Dip Med Vet, M MED VET, DACVIM

Assessment and management of pain associated with lameness in cattle

Jan K. Shearer et al. — Thu, 16 May 2013 12:52:05 PDT

Lameness impacts the cattle industry in economic losses and welfare considerations. In addition to production deficits, pain and distress associated with lameness have been documented. The evaluation and prevalence of lame cattle is one of the primary factors in third-party welfare audit programs. To improve earlier detection and treatment of lameness, locomotion scoring systems have been developed for routine use by farm employees. Recommendations for pain management typically include the use of a multimodal therapeutic approach. Similarly, in lame cattle, pain can best be alleviated by implementing a multimodal approach including corrective claw trimming and placement of foot blocks combined with additional benefits provided by analgesic compounds.

Vulvar pythiosis in two captive camels (Camelus dromedarius)

Ricardo Videla et al. — Tue, 23 Apr 2013 17:17:57 PDT

Two camels (Camelus dromedarius), 3- and 4-years-old, respectively, from an eastern Tennessee wildlife farm presented with persistent weight loss and large vulvar masses. An initial biopsy of the vulvar mass of one of the camels performed by a local veterinarian showed eosinophilic dermatitis. An allergic or parasitic dermatitis was suspected. The two camels were treated with one dose of sodium iodide (66 mg/kg, in 1.0 L of normosolR, IV) and ivermectin 1% (200 ug/kg PO). Upon presentation at the Veterinary Teaching Hospital, University of Tennessee, additional biopsies of the masses again revealed eosinophilic dermatitis. Microscopic examination of a Gomori methenamine silver (GMS)-stained section prepared from the biopsy of one of the camels revealed the presence of fungal-like hyphae of a mold which was suspected to be Pythium insidiosum. The vulvar masses were surgically debulked in both animals and sodium iodide and Pythium-immunotherapy prescribed. Pythium insidiosum was isolated in culture and hyphae elements were detected in histological sections confirming the diagnosis of pythiosis in both animals. Despite signs of progressive healing of the vulvar surgical areas, postoperative persistent weight lost in one of the camels suggested the possibility of gastro intestinal (GI) tract pythiosis. This camel died 5 months after the first onset of clinical signs and unfortunately a necropsy was not performed. The other camel responded well to the combination of surgery, iodides, and im

Clinical diagnosis of foot and leg lameness in cattle

J K. Shearer et al. — Sat, 03 Nov 2012 19:05:50 PDT

The causes of lameness in cattle are multifactorial and involve a combination of housing, management, and environmental factors and a variety of infectious agents. Arriving at a cause can often require concerted efforts. Diagnosis of lameness is often based mainly on clinical observations. A detailed record of those observations with time and among several animals within a herd can provide valuable information toward solving lameness problems. Advances in computer hardware and software help facilitate more detailed data collection and analysis.

Vulvar pythiosis in two captive camels (Camelus dromedarius).

Ricardo Videla et al. — Fri, 10 Feb 2012 08:01:19 PST

Lameness in Dairy Cattle

Jan K. Shearer et al. — Fri, 13 Jan 2012 10:28:44 PST

Cloning adult farm animals: a review of the possibilities and problems associated with somatic cell nuclear transfer

J Lannett Edwards et al. — Fri, 13 Jan 2012 10:24:59 PST

In 1997, Wilmut et al. announced the birth of Dolly, the first ever clone of an adult animal. To date, adult sheep, goats, cattle, mice, pigs, cats and rabbits have been cloned using somatic cell nuclear transfer. The ultimate challenge of cloning procedures is to reprogram the somatic cell nucleus for development of the early embryo. The cell type of choice for reprogramming the somatic nucleus is an enucleated oocyte. Given that somatic cells are easily obtained from adult animals, cultured in the laboratory and then genetically modified, cloning procedures are ideal for introducing specific genetic modifications in farm animals. Genetic modification of farm animals provides a means of studying genes involved in a variety of biological systems and disease processes. Moreover, genetically modified farm animals have created a new form of 'pharming' whereby farm animals serve as bioreactors for production of pharmaceuticals or organ donors. A major limitation of cloning procedures is the extreme inefficiency for producing live offspring. Dolly was the only live offspring produced after 277 attempts. Similar inefficiencies for cloning adult animals of other species have been described by others. Many factors related to cloning procedures and culture environment contribute to the death of clones, both in the embryonic and fetal periods as well as during neonatal life. Extreme inefficiencies of this magnitude, along with the fact that death of the surrogate may occur, continue to raise great concerns with cloning humans.

Pharmacokinetics of Intravenous and Intramuscular Tramadol in Llamas

Sherry Cox et al. — Thu, 26 May 2011 12:31:09 PDT

The purpose of this study was to determine the pharmacokinetics of tramadol and its metabolite M1 after intravenous and intramuscular administration to llamas. Tramadol, a centrally acting analgesic whose efficacy is a result of complex interactions between opiate, adrenergic and serotonin receptor systems, has been used clinically to treat moderate to severe pain in humans. The pharmacokinetic parameters of tramadol and M1 in plasma were examined following intravenous and intramuscular administration to six healthy male llamas. Tramadol half-life, volume of distribution at steady-state and clearance after intravenous administration were 2.12 ± 0.37 h, 4.02 ± 1.16 L/kg and 1728.73 ± 152.82 mL/h/kg, respectively. The bioavailability was 110 ± 21% and half-life 2.54 ± 0.31 h following intramuscular administration of tramadol. M1 had a half-life of 10.40 ± 2.90 h and 7.71 ± 0.54 h following intravenous and intramuscular administration of tramadol.

Uterine Lesions in 32 Female Miniature Pet Pigs

Marcia R. S. Ilha et al. — Thu, 26 May 2011 12:26:40 PDT

Thirty-two 4-month-old to 19-year-old female miniature pet pigs were spayed. Uterine lesions were present in all except 8 pigs. The 24 remaining pigs had diffuse cystic endometrial hyperplasia, of which 14 had smooth muscle tumors, including leiomyomas and leiomyosarcomas, in the uterus or broad ligament. Nodular endometrial lesions—including adenocarcinomas, adenomas, and/or adenomyosis—were present in 10 pigs, 3 of which had concurrent smooth muscle tumors. Pyometra was present in 3 pigs. In uterine sections with cystic endometrial hyperplasia, adenomyosis, or adenomas, approximately 70% of epithelial nuclei expressed estrogen receptor and progesterone receptor immunohistochemically; in adenocarcinomas, expression was 20%. Regardless of malignancy, more than 50% of nuclei in smooth muscle tumors expressed estrogen receptor and progesterone receptor. Aging was associated with the development of uterine lesions in miniature pet pigs.

Claw Horn Growth and Wear Rates, Toe Length, and Claw Size in Commercial Pigs: A Pilot Study

Sarel R. Van Amstel et al. — Thu, 26 May 2011 12:20:11 PDT

Mean claw horn growth and wear rates in three commercial gilts were greater for rear feet and for the caudal wall. Outer and inner claws differed in size for rear feet, but not for front feet. Lesions occurred mainly in the outer claws of rear feet.

Bovine Viral Diarrhea Infections in New World Camelids—A Review

Sarel R. Van Amstel et al. — Thu, 26 May 2011 12:14:49 PDT

Bovine virus diarrhea virus (BVDV) has recently been identified as an important infectious disease of new world camelids (NWC) particularly alpacas. Both sub-genotypes 1a, 1b and genotype 2 have been isolated. However, non-cytopathic BVDV 1b is reported to be primarily implicated in cases of BVDV in NWC's. Although suspected a BVDV strain unique to camelids have not been isolated. The most important source of BVDV is the immuno-tolerant persistently infected cria. Natural transient infection of BVDV in NWCs is reported to go almost undetected except for vague signs of illness, including lethargy and anorexia. Diarrhea does not appear to be a constant finding. Embryonal/fetal disease in NWC's includes early pregnancy loss, abortion and premature birth or the birth of persistently infected crias. Persistently infected disease can occur in both acute and chronic forms. In NWCs the chronic form of the condition is most commonly reported. Signs include chronic ill-thrift, poor weight gain or being underweight, intermittent illness, chronic diarrhea, joint swelling and episodes of nasal discharge and pneumonia despite antibiotic treatment. The mortality rate in NWCs appears to be close to 100%. Seroprevalence of BVDV in NWCs ranged from 2.05% to 11.11% however the possibility that the correct (homologous) BVDV strain is not being used in serological assays need to be considered. The importance of cattle as a source of BVDV for camelids is unclear although there is consensus of a spill-over from cattle to NWC's. Assays available for BVDV in cattle appear to work for camelids. An antigen ELISA which is the usual method for detecting BVD in cattle has not been validated in NWC's.

Ivermectin Concentrations in Serum and Cerebrospinal Fluid after Intravenous Administration to Healthy Llamas

Sarel R. Van Amstel et al. — Thu, 26 May 2011 12:10:21 PDT

The response to anthelmintic treatment in clinical cases of meningeal worm (Parelaphostrongylus tenuis) infestation remains unpredictable. In a previous study, ivermectin (IVM) was not detected in cerebrospinal fluid (C.S.F.) following subcutaneous administration to healthy llamas of IVM at 500μg/kg. In the present study, the same IVM dose was added to 1 L 0.9% NaCl and administered intravenously over 30 minutes to 6 healthy llamas. C.S.F and blood were collected, at baseline and 2, 4, 6, 12, 24, 48 and 60 hr after IVM administration. Serum and C.S.F. were stored at -40⁰C and IVM concentration was determined using high performance liquid chromatography (H.P.L.C.). No IVM was detected in the serum or C.S.F. in baseline samples. Concentrations of IVM ranging from 2291- 7742 ng/ml were present in serum at 2 hr post dosing but values decreased to between 103-615 ng/ml at the 4 hr sampling, and ranged from 11- 48 ng/ml at 60hr. Low concentrations of IVM were found in the C.S.F. of all llamas on at least one of the sampling times. Immediately after administration of IVM three of the llamas showed transient lethargy and decreased appetite for 12-24 hours. One llama developed acute neurological signs 7 days after IVM administration and was euthanased three days later. Histopathologic examination revealed diffuse myelinic oedema in the brain and spinal cord. Two other llamas developed C.S.F. changes consistent with septic inflammation. C.S.F. concentrations of IVM can be achieved following I.V. administration at 500μg/kg, however, because of the possibility of neurological damage, I.V. administration of IVM at this dose is not recommended.

Clinical Report: Thin Sole Associated Sole Ulcer: Characterization of the Lesion

Sarel R. Van Amstel et al. — Thu, 26 May 2011 12:04:42 PDT

Review of Pododermatitis Circumscripta (Ulceration of the Sole) in Dairy Cows

Sarel R. Van Amstel et al. — Thu, 26 May 2011 12:01:53 PDT

Sole ulcers are among the most frequent causes of lameness in dairy cattle. They are found most commonly in the hind lateral claw, are frequently bilateral, and have a high rate of reoccurrence. The pathogenesis of sole ulceration is primarily based on mechanical injury by the 3rd phalanx to the corium, basement membrane, and basal layers of the sole epidermis as a result of failure of the suspensory apparatus in the claw. The main pathways in the failure of the suspensory system include inflammatory (dermal vascular changes followed by disruption of keratinocyte proliferation and differentiation caused by local and systemic mediators) and noninflammatory (hormonal and biochemical changes in the peripartum period resulting in alterations of connective tissue in the suspensory system) pathways. Sole ulcers tend to occur in specific locations; the most reported site is the junction of the axial heel and sole. Other locations include the apex of the toe and the heel. Varying degrees of lameness may result, and the most severe are seen with complicated cases in which ascending infection affects the deeper structures of the claw. Pathologic changes at the ulcer site include dyskeratosis and dilated horn tubules with microcracks. Vascular changes include dilatation and thrombosis of capillaries with “neocapillary formation.” Areas of dyskeratosis may remain for as long as 50 days at the ulcer site. Treatment includes corrective trimming and relief of weight bearing. Complicated cases may require surgical intervention.

Ocular Dermoids in Cattle: a Case Report

Jose R. Castro et al. — Thu, 26 May 2011 11:56:02 PDT

Effects of Dexamethasone and Isoflupredone Acetate on Plasma Potassium Concentrations and Other Biochemical Measurements in Dairy Cows in Early Lactation

Natalie J. Coffer et al. — Thu, 26 May 2011 10:45:19 PDT

Objective—To determine whether administration of isoflupredone acetate (ISO) to healthy cows increases the frequency of severe hypokalemia and whether dexamethasone (DEX) has detectable mineralocorticoid properties.

Animals—33 cows at 20 to 25 days of lactation.

Procedures—Cows were randomly allocated to 5 treatment groups and received 2 IM injections (on days 0 and 2) of sterile saline (0.9% NaCl) solution (10 mL each), an injection of ISO (20 mg) or DEX (20 mg) followed by 10 mL of saline solution, or 2 injections of ISO or DEX. Milk production was measured, physical examinations were performed, and blood and urine samples were collected daily on days 0 through 7.

Results—Physical examination parameters did not differ among groups; however, 1 cow developed atrial fibrillation on day 4. Both corticosteroids significantly increased plasma glucose concentrations, and ISO significantly decreased plasma potassium concentrations and increased total carbon dioxide concentrations with time. One dose of ISO decreased mean plasma potassium concentration by 25% on day 2, compared with day 0, and severe hypokalemia (serum potassium concentration < 2.3 mEq/L) developed in 1 of 6 cows. Mean plasma potassium concentration was 46% lower on day 3 than on day 0 in cows receiving 2 doses of ISO, and 5 of 7 cows became severely hypokalemic. Mean urinary fractional excretion of potassium significantly increased from that on day 0 in cows receiving 2 doses of ISO.

Conclusions and Clinical Relevance—Both corticosteroids had glucocorticoid activity; however, only ISO had mineralocorticoid activity. Compared with saline solution, administration of 2 doses of ISO significantly increased the frequency of severe hypokalemia.

Measurement of the Thickness of the Corium and Subcutaneous Tissue of the Hind Claws of Dairy Cattle by Ultrasound

Sarel R. Van Amstel et al. — Thu, 26 May 2011 10:27:22 PDT

The thickness of the subsolar soft tissue layer (dermis and subcutaneous tissue) of the hind lateral and medial claws of 23 Holstein dairy cattle was measured by ultrasound imaging. The results showed that on average the subsolar soft tissue layer of the lateral hind claw was significantly thicker (4.29 mm) than that of the medial hind claw (3.92 mm).

A Record- Keeping System for Capture of Lameness and Foot-Care Information in Cattle

Jan K. Shearer et al. — Thu, 26 May 2011 09:34:54 PDT

Moisture Content, Thickness, and Lesions of Sole Horn Associated with Thin Soles in Dairy Cattle

Sarel R. Van Amstel et al. — Thu, 26 May 2011 09:11:55 PDT

Thin soles and resulting lameness are often associated with increased culling rates in large dairy operations. The moisture content of the sole horn may cause the horn to be softer, thus predisposing it to an increased rate of wear. For that reason, the first objective of this study was to determine the moisture content of the sole horn of thin-soled cows. The second objective was to document physical changes of the claw associated with thin soles. Twenty-six adult Holstein cows showing signs of thin soles, and 16 normal cows were used in the study. Selection criteria for thin-soled cows included a dorsal wall length of less than 7.5cm and the following clinical signs: painful gait, arched back, and specific leg lameness. Sixteen normal adult cows with dorsal wall length in excess of 7.5cm were randomly selected. For thin-soled cows, the moisture contents of sole horn were 37.1±0.7% for front claws and 40.5±0.7% for rear claws. These values were significantly different from each other. Moisture contents of sole horn from normal cows were 31.08±0.93% for front claws and 33.1±0.9% for rear claws, which were significantly different from each other and different from thin-soled cows. Rear claws had higher moisture contents than front claws. Mean sole horn thickness was 4.23±0.18mm for the rear lateral claws and 5.15±0.18mm for the rear medial claws. The average dorsal wall lengths were 66.8±3.94mm for rear lateral claws and 69.1±7.25mm for rear medial claws. Thirty percent of rear feet with thin soles had pathological claw horn lesions including sole/white line separation (72%) and sole ulcers (28%). Of the affected claws, 13% had more than one lesion. Seventy-seven percent of claw lesions occurred in the lateral claw.

Effect of Dimethyl Sulfoxide in the Treatment of Sheep Experimentally Infected with Ehrlichia Ruminantium

L. C. Cedric et al. — Thu, 26 May 2011 08:59:46 PDT

Objective—To evaluate the clinical response of sheep experimentally infected with Ehrlichia ruminantium to treatment with dimethyl sulfoxide (DMSO).

Animals—32 Merino crossbred sheep.

Procedure—16 sheep were infected with E ruminantium; 8 of these were treated twice daily with a 10% solution of DMSO (1 g/kg, IV) in polyionic fluid for 3 consecutive days. Treatment was initiated 2 days after the onset of clinical disease. Eight uninfected control sheep were similarly treated with DMSO. Placebo treatments (polyionic fluid administrations) were given to 8 infected and 8 uninfected sheep. Arterial and venous blood samples for blood gas and total plasma protein concentration measurements were collected daily (data from 5 days before until 6 days after onset of clinical disease were analyzed); physiologic variables and food consumption were also monitored. Gross pathologic findings and cytologic confirmation of the disease were recorded for the 16 infected sheep.

Results—Infected sheep treated with DMSO were able to maintain pulmonary gas exchange and had reduced pleural effusion and plasma protein loss, compared with infected untreated sheep that became hypoxic. Infected treated sheep developed an uncompensated metabolic acidosis. Uninfected treated sheep had reduced appetite, whereas uninfected untreated sheep maintained normal food intake.

Conclusions and Clinical Relevance—Results of DMSO treatment in sheep with experimentally induced heartwater disease indicated that administration of this agent, in combination with specific antimicrobial treatment, may be of some benefit in treatment of naturally occurring disease.

Cloning Adult Farm Animals: A Review of the Possibilities and Problems Associated with Somatic Cell Nuclear Transfer

J. Lannett Edwards et al. — Thu, 26 May 2011 07:43:28 PDT

In 1997, Wilmut et al. announced the birth of Dolly, the first ever clone of an adult animal. To date, adult sheep, goats, cattle, mice, pigs, cats and rabbits have been cloned using somatic cell nuclear transfer. The ultimate challenge of cloning procedures is to reprogram the somatic cell nucleus for development of the early embryo. The cell type of choice for reprogramming the somatic nucleus is an enucleated oocyte. Given that somatic cells are easily obtained from adult animals, cultured in the laboratory and then genetically modified, cloning procedures are ideal for introducing specific genetic modifications in farm animals. Genetic modification of farm animals provides a means of studying genes involved in a variety of biological systems and disease processes. Moreover, genetically modified farm animals have created a new form of ‘pharming’ whereby farm animals serve as bioreactors for production of pharmaceuticals or organ donors. A major limitation of cloning procedures is the extreme inefficiency for producing live offspring. Dolly was the only live offspring produced after 277 attempts. Similar inefficiencies for cloning adult animals of other species have been described by others. Many factors related to cloning procedures and culture environment contribute to the death of clones, both in the embryonic and fetal periods as well as during neonatal life. Extreme inefficiencies of this magnitude, along with the fact that death of the surrogate may occur, continue to raise great concerns with cloning humans.