Opportunities and obstacles in veterinary dental drug delivery.

Dentistry is a relatively new field in veterinary medicine, despite the fact that dental disease is common in dogs and cats. Obstacles to the development of dental treatments in animals include the diversity of the dentition among the species, the difficulty in administration of oral treatments, the different presentations of oral disease, and the cost of regulatory approval for each species. Mechanical removal of plaque and calculus has been the mainstay of periodontal disease treatment in animals and humans. New adjunctive therapies, as well as new applications for older drugs, are being introduced for periodontal therapy.

Nonsurgical periodontal therapy.

The primary etiology of periodontal disease is bacterial infection. Bacteria exist as a biofilm (plaque) on the tooth and soft-tissue surfaces of the mouth. Biofilm is extremely resistant to antimicrobial activity. To effectively treat periodontal disease, the bacterial load must be reduced to allow healing of the inflamed tissues. Reduction of the bacterial load can be accomplished by surgical methods, nonsurgical methods, or a combination of the two. This article focuses on the nonsurgical treatment of periodontal disease. A thorough oral examination, which includes visual inspection and the use of a periodontal probe, is needed to determine the best therapy. Supragingival cleaning with power and hand scalers is the first step in the therapy process. The next step, subgingival scaling, is necessary to remove bacteria that are in direct contact with the periodontium. Effective subgingival plaque removal is time intensive and requires motivation, manual dexterity, and meticulous technique. Most veterinarians and veterinary technicians lack the training, instruments, and time to remove subgingival plaque effectively. To improve therapeutic results, adjunctive therapy in the form of oral systemic antibiotics or a locally applied doxycycline-containing polymer may be used. The success of periodontal therapy also is dependent on dental home care that takes place after professional treatment. The veterinarian and staff must be willing to educate and reinforce the dental home care efforts of the pet owner.

The longevity of sterilized aortic valve homografts 1966-1972.

Between 1966 and 1972 seventy-two adult patients underwent aortic valve replacement with unstented aortic valve homografts prepared by chemical beta-propiolactone sterilization and storage. There were 5 hospital deaths and 6 foreign patients are lost to follow-up. Of the remaining 61, there have been 7 late deaths. Thirty-one patients have needed re-operation and 6 of them died. To date, 13 patients still have their homografts--none take anticoagulants and endocarditis has not occurred. The technique for valve preparation is not currently used anywhere, but the results, especially with respect to freedom from endocarditis and from calcification compare most favourably with current methods. The relative freedom from calcification suggests that it may still have relevance to the problems of aortic and pulmonary valve replacement in children.

Reoperation for failed aorto-coronary bypass grafts.

Despite the initial overall good results of aorto-coronary bypass grafting for myocardial revascularisation, a small but increasing number of patients require consideration for reoperation after the first procedure. In the period 1973 to 1981, 36 reoperations were performed in 34 patients with one operative death. In all of them the clinical indication for reoperation was recurrence of angina pectoris. In this special group of patients a high incidence of risk factors was present. Three major probable causes for the recurrence of angina were found: (1) Progression of the coronary atherosclerotic disease; (2) Graft failure; (3) Incomplete original revascularisation. Combined factors were present in 18 (53%) patients. There were no statistically significant differences in the incidence of postoperative complications at the first and second operation. Follow-up of 79% of the 33 survivors over a mean time period of 18 months, demonstrated no late mortality and a low subsequent infarction rate. Overall 69% of patients either lost their angina or were improved. We therefore conclude that reoperation can be accomplished with low mortality and morbidity and has a potential therapeutic benefit in the majority of cases.

A comparison of two prophylactic antibiotic regimes for open-heart surgery.

Two groups of patients undergoing open-heart surgery were given prophylactic courses of antibiotic lasting five days. One group (61 patients) received a cephalosporin and the second (57 patients) received a combination of penicillin, flucloxacillin and streptomycin. The overall major infection rate was low (3--4%), particularly so in the cephalosporin group (1.6%). There was no increased nephrotoxic effectt of the cephalosporin, and any nephrotoxic effect that was present was temporary and clinically unimportant. The major infecting organism in both groups was Staphylococcus albus (Staph. epidermidis). The efficiency, therefore, of any prophylactic regime which omits gentamicin, to which Staph. albus in usually sensitive, remains in doubt.

Collagen diseases as a cause of constrictive pericarditis.

Seven patients with constrictive pericarditis associated with collagen disease underwent pericardiectomy with good results in all but one. The collagen disease was confirmed as rheumatoid arthritis in five patients, but in two its nature remained obscure. In one case the illness was marked by a persistent eosinophilia and eosinophilic infiltration of the pericardium. The association of constrictive pericarditis with rheumatoid arthritis and other collagenoses is briefly discussed.

Observations on the treatment of dissection of the aorta.

The results are presented of treatment in twenty-three patients with dissection of the thoracic aorta, in four of whom it was acute (less than 14 days' duration), and in nineteen chronic (more than 14 days' duration). Sixteen patients had Type I and II dissection (involving the ascending aorta) and five Type III (descending aorta at or distal to the origin of the left subclavian artery); in two, dissection complicated coarctation of the aorta in the usual site. Thirteen patients had aortic regurgitation. Three of the patients with acute dissection were treated medically; two, both with Type I dissection, died, and the third, with Type III, survived. The remaining acute patient was treated surgically and also died. Of the patients with chronic dissection, eight were treated medically and eleven surgically. None of the medical group died in hospital; three died between 3 months and 1 year, and five have survived from periods of 12-72 months. Eleven patients with chronic dissection were treated surgically; four died in hospital at or shortly after operation; and the remaining seven lived for periods of 12-84 months. The presentation, indications for surgical treatment and results are discussed. It is concluded that surgical treatment of chronic dissection may carry a higher initial mortality than medical, but that there may be slightly better overall long term results in the former. As this series was not selected randomly, because patients with complications were selected for surgery, and there are only a few patients in each group, the results do not permit firm conclusion regarding the relative merits of medical and surgical treatment. It is suggested that all patients should initially be treated medically but that surgical treatment should be considered if the dissection continues, if aortic regurgitation is severe, if an aneurysm develops or enlarges, if cardiac tamponade develops or there is evidence of progressive involvement of the branches of the aorta. Attention is drawn to the important syndrome of chronic dissecting aneurysm of the ascending aorta with severe aortic regurgitation which requires definitive surgical treatment and aortic valve replacement. The importance of adequate visualization of the origin and extent of the dissection as a preliminary to surgical treatment is stressed.

Coarctation of the aorta in infancy and childhood.

The management and results of treatment in 181 children with coarctation of the aorta are presented. In this series, 79% of the patients presented in the first year of life and 55% presented as neonates. One hundred and fifty patients were operated on, with a total surgical mortality of 21%. Only one surgical death occurred in those operated on after 3 months of age. The higher mortality in young infants is closely related to associated cardiac anomalies and to the frequency of aortic and isthmal hypoplasia. Our findings suggest that neonates presenting with heart failure and coarctation should be operated on early, as the surgical mortality under 6 weeks is 45%, whereas there is an 86% mortality in neonates who were not operated on. Analysis of follow-up indicates that when operation can be performed electively the optimal period for sugical treatment is between 6 months and 1 year of age. If operation is performed after this age, there may be persistent systemic hypertension despite relief of aortic obstruction.

Physiological activity in mediastinal teratomata.

The clinical details of two patients with benign mediastinal teratomata are presented. Both patients developed inflammation of the root of the neck, the first after a small dose of radiotherapy and the second after a larger dose of radiotherapy and exploration of the thoracic inlet. In both cases, exploration of the inflamed area was followed by persistent discharge of fluid which was sterile on culture. In the first case, this was found to have a high cholesterol, lipid, and amylase content. In both cases, a benign mixed teratoma, with contents including intestinal epithelium and pancreatic tissue, was removed at thoracotomy. The suggestion is made that leakage of digestive enzymes from pancreatic, intestinal or salivary tissue may be a cause of inflammation in and around teratomata, especially after surgical exploration. Early thoracotomy is advised when the condition is recognized.