Ocular distribution and toxicity of intravitreal injection of triamcinolone acetonide in normal equine eyes

Objective  To determine ocular distribution and toxicity of a single injection of intravitreal triamcinolone acetonide (TA) in normal horses.
Animals studied  Six adult horses, donated to North Carolina State University.
Procedures  Six horses were injected intravitreally with either 10, 20, or 40 mg ( n  = 2 each) of TA. The opposite eye of each horse was injected with balanced salt solution (BSS). Ocular toxicity was assessed by biomicroscopy, tonometry, indirect ophthalmoscopy, and electroretinogram. Aqueous humor (AH), vitreous humor (VH), and plasma samples were collected. Horses were euthanized 7 or 21 days after injection and eyes enucleated for histopathology. TA concentrations in AH, VH, and plasma were measured by HPLC.
Results  Three control eyes and one TA eye developed inflammation after injection or collection of AH. Positive bacterial cultures ( Corynebacterium spp., Staphylococcus spp., and Streptococcus spp.) were obtained from three of these eyes. Other than transient corneal edema in TA injected eyes, which resolved by 7 days after injection, no other changes were observed. TA crystals were visible within the vitreous body. No evidence of TA toxic effect was noted on histopathology. TA was detected in all AH and VH samples from treated eyes following injection. Drug was not detected in the plasma.
Conclusions  There was no evidence of overt toxicity from intravitreal TA in normal horses and a single intravitreal injection resulted in TA ocular levels for 21 days. However, the risk for bacterial infections with intravitreal injection or anterior chamber aspirations in horses is high. Use of topical and systemic antibiotics after injection is recommended.     

Prevalence of dental disorders in 483 horses and ponies

Prevalence of dental disorders in 483 horses and ponies Five equine veterinarians working at three equine referral hospitals examined the oral cavity of 483 horses and ponies prior to surgery, to gain information about the prevalence of common dental disorders in the horse. A thorough examination, using hands/fingers, a full-mouth speculum, a dental mirror and a good light source, is essential to detect such disorders. Many horses examined needed dental attention even though there were no problems with mastication or riding. The most detected abnormalities were sharp enamel points on the buccal side of the upper arcade and the lingual side of the lower arcade, and hooks at 106/206 and 311/411. Regular dental care would improve the condition and welfare of horses.     

Extensive umbilical herniation of the large colon in a foal

A 5‐month‐old Warmblood cross colt was presented with focal swelling of the ventral abdomen extending from the umbilicus to the scrotum in the absence of colic signs. Palpation and ultrasound examination revealed the presence of incarcerated large intestine within the subcutaneous space adjacent to the caudal ventral abdomen and prepuce. Surgery was performed and revealed that the umbilical hernia sac had ruptured, and confirmed that the left dorsal and ventral colon were present in the subcutaneous space. The mild degree of vascular compromise of the large colon did not necessitate resection and so it was replaced within the abdomen. The abdominal wall defect was closed and the subcutaneous dead space was reduced by using a walking suture pattern. Herniation of the large colon through the umbilicus with dissection through the subcutaneous tissues of the ventral abdominal wall and prepuce has not been previously reported in foals. Ultrasonography permits differentiation of herniated small intestine from large intestine.     

Stress and immunological response of heifers divergently ranked for residual feed intake following an adrenocorticotropic hormone challenge

Background: When an animal is exposed to a stressor, metabolic rate, energy consumption and utilisation increase primarily through activation of the hypothalamic-pituitary-adrenal(HPA) axis. Changes to partitioning of energy by an animal are likely to influence the efficiency with which it is utilised. Therefore, this study aimed to determine the physiological stress response to an exogenous adrenocorticotropic hormone(ACTH) challenge in beef heifers divergently ranked on phenotypic residual feed intake(RFI).Results: Data were collected on 34 Simmental weaning beef heifers the progeny of a well characterized and divergently bred RFI suckler beef herd. Residual feed intake was determined on each animal during the postweaning stage over a 91-day feed intake measurement period during which they were individually offered adlibitum grass silage and 2 kg of concentrate per head once daily. The 12 highest [0.34 kg DM/d] and 12 lowest[-0.48 kg DM/d] ranking animals on RFI were selected for use in this study. For the physiological stress challenge heifers(mean age 605 ± 13 d; mean BW 518 ± 31.4 kg) were fitted aseptically with indwelling jugular catheters to facilitate intensive blood collection. The response of the adrenal cortex to a standardised dose of ACTH(1.98 IU/kg metabolic BW~(0.75)) was examined. Serial blood samples were analysed for plasma cortisol, ACTH and haematology variables. Heifers differing in RFI did not differ(P = 0.59) in ACTH concentrations. Concentration of ACTH peaked(P 0.001) in both RFI groups at 20 min post-ACTH administration, following which concentration declined to baseline levels by 150 min. Similarly, cortisol systemic profile peaked at 60 min and concentrations remained continuously elevated for 150 min. A RFI × time interaction was detected for cortisol concentrations(P = 0.06) with high RFI heifers had a greater cortisol response than Low RFI from 40 min to 150 min relative to ACTH administration. Cortisol response was positively associated with RFI status(r = 0.32; P 0.01). No effect of RFI was evident for neutrophil, lymphocytes, monocyte, eosinophils and basophil count. Plasma red blood cell number(6.07 vs. 6.23; P = 0.02) and hematocrit percentage(23.2 vs. 24.5; P = 0.02) were greater for low than high RFI animals.Conclusions: Evidence is provided that feed efficiency is associated with HPA axis function and susceptibility to stress, and responsiveness of the HPA axis is likely to contribute to appreciable variation in the efficiency feed utilisation of cattle.     

Pharmacokinetics of liposomal encapsulated buprenorphine suspension following subcutaneous administration to cats

We investigated the effects of liposome encapsulation at prolonging the systemic exposure of buprenorphine following subcutaneous administration in cats. Seven healthy male cats were dosed intravenously with 0.02 mg/kg buprenorphine solution (STD‐BUP), followed 14 days later by a subcutaneous injection of 0.2 mg/kg buprenorphine as a liposomal suspension (SUS‐BUP) containing drug molecules both in liposomes and the suspending vehicle. Buprenorphine time plasma concentration data for both dosing routes were analyzed simultaneously with four compartmental models. Goodness of fit was assessed both graphically and with the Akaike information criterion. The time‐course of intravenous STD‐BUP was biphasic, with a 4.39 h average terminal half‐life. The subcutaneous SUS‐BUP produced plasma buprenorphine concentrations above 0.5 μg/L for more than 96 h, with three distinct peaks in the first 15 h. The model with best fit comprised a central and a peripheral compartment, plus three subcutaneous absorption compartments: one of dissolved drug molecules that were absorbed through a first‐order process, and two of liposome‐encapsulated drug molecules that were transferred to the solution compartment through separate zero‐order processes. Liposomes effectively prolonged the systemic exposure of buprenorphine in cats.     

Congenital pyloric stenosis in two kittens corrected by pyloroplasty

Abstract

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Rural veterinary practice faces difficulties in many parts of the world. Falling farm incomes and increasing costs have sometimes resulted in reduced use of veterinary services. There seems to be widespread agreement that an increased emphasis on preventive medicine would improve the situation for both the farmer and his veterinarian. There appear to be no commonly agreed formal criteria for the development and evaluation of health programmes, either in human or veterinary medicine, but increasing attention is being paid to the problem(1) Anon Statistical indicators for the planning and evaluation of public health programmes: 11th report of the World Health Organisations expert committee on health statistics W. H. O. Tech. Reports No. 365 1971  [Google Scholar] (12) Morris, R. S. 1969. Assessing the ecnomic value of veterinary services to primary industries. Aust. vet. J., 45: 295–300.  [Google Scholar] (14) Morris, R. S. 1975. Criteria for the design and evaluation of bovine mastitis control systems. International Dairy Federation Proceedings, 85: 395–409. In [Google Scholar] (15) Schulberg, H. C., Sheldon, A. and Baker, F., eds. 1970. Program evaluation in the health fields, N.Y.: Behavioural Publications.  [Google Scholar], In some ways the evaluation of animal health programmes should be the easier, for there are fewer ethical problems and economic criteria are of paramount importance in rural practice.     

Experimental observations on prophylactic and therapeutic vaccination against foot-rot in sheep

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I have taken as my subject for this address the topic, “Change”, and will deal with two aspects of change, one the challenge of change due to new knowledge and techniques and second the change we must make in our attitude to other agricultural disciplines and ancillary veterinary personnel.