TREATMENT

Principles of treatment are summarised in Table 32.1.

Early to relatively advanced cases of MPPD can be suc­cessfully treated with appropriate management. Euthana­sia should be considered in severe cases and when required treatment intensity will be, or proves to be, unacceptably stressful.

4.1. Physical manipulation

Scaling plaque and calculus from teeth and periodontal pockets, extraction of compromised teeth (Fig. 32.3; see Chapter 13) and debridement of necrotic tissue are key to achieving clinical resolution. Extraction sites often heal adequately when left open. Hoyer et al. (2020) described surgical techniques for the intraoral extraction of incisors and the extraoral extraction of premolars and molars via a horizontal skin incision. Antibiosis alone, without extraction of affected teeth, has not resolved disease in swamp wallabies (Wallabia bicolor) or red-necked walla­bies (Kido et al. 2013; Hoyer et al. 2020).

In early stage cases, without significant exudate or osteomyelitis, physical interventions can achieve resolu­tion without long-term antibiosis. More advanced cases, with multiple compromised teeth and/or osteomyelitis, require aggressive debridement and often, long-term antibiosis. Intraoperative haemorrhage can obscure visu­alisation of the site and necrotic tissue may take time to completely declare. Treatment under anaesthesia q 2-4 d may be required until all infected or necrotic tissue is removed. Follow-up examination (including imaging) q 1-2 wk, then at more extended intervals, is recom­mended until complete resolution is achieved. Areas of non-healing gingiva or draining fistulae generally indi­cate retained tooth root fragments or bony sequestra that require extraction.

Affected lower incisors, both unilaterally (Grifols et al. 2013; Kane et al. 2017) (Fig. 32.5) and bilaterally, can be extracted successfully. A mandibular incisor with

Table 32.1. Treatment principles for macropod progressive periodontal disease

Physical manipulation - critical to achieve clinical resolution

• Removal of plaque and calculus

• Extraction of compromised teeth (see Chapter 13)

• Aggressive debridement of necrotic tissue

Microbial manipulation

• Resolution of early-stage disease can be achieved with minimal antibiosis, provided adequate physical manipulations

• Aggressive antibiosis is required for osteomyelitic lesions

• Consider both local/regional and systemic antibiosis

• Target anaerobes, especially in early stage disease; may promote restoration of stable oral microbiome

Supportive care

• Analgesia

• Nutritional support

• Consider tolerance of patient to the required intensity of treatment

• Minimise stressors ± use of behaviour modifying drugs

Identify and address contributing factors

periapical osteomyelitis was successfully treated using endodontic techniques to preserve the tooth (Kilgallon et al. 2010).

In severe cases, with proliferative necrotising osteo­myelitis, euthanasia is frequently indicated (Fig. 32.3). Prognosis, even with significant surgical and medical management is often poor. Tolerance of intensive man­agement by individuals may be low, resulting in stress, compromised welfare and poor therapeutic outcomes. However, aggressive surgery to debride necrotic tissue can be successful. A red-necked wallaby with a chronic draining sinus below the right eye was successfully man­aged with extensive debridement of facial and periocular soft tissue and bone, including enucleation. The defect was filled with a transposition flap (Remedios et al. 1996).

4.2. Microbial manipulation

Treatment of oral lesions should aim to suppress patho­genic bacteria and seek to restore a healthy stable oral microbiome (see section 2.1) (Marsh et al.

Treatment protocols that include broad-spectrum antimicrobials and/or antiseptics are often successful at resolving early-stage periodontal lesions. However, the indiscriminate reduction in bacterial load with such treatments may result in an oral microbial community structure that predisposes to disease recurrence (Antia- bong et al. 2014). Narrow-spectrum antimicrobials that target anaerobes, but preserve gram-negative aerobes (see section 2.1), are more likely to allow a healthy oral micro­biome to re-establish. Resolution of osteomyelitic infec­tions necessitates re-establishing sterile conditions in extra-oral sites and broad-spectrum antibiotics may be required; local/regional provision of antibiosis may be sufficient to provide this with minimal effect to oral flora.

Protocols incorporating targeted short-acting injecta­ble antibiotics have been used successfully (Kane et al. 2017). However, they rely on the animal being suitably tolerant of the intensity of treatment. Early-stage cases not requiring ongoing antibiosis may still benefit from perio­perative antibiosis, to minimise the risk of haematogenous dissemination associated with physical manipulations.

Long-acting injectable antimicrobials are often used to reduce the frequency of handling. However, plasma concentrations of oxytetracycline and penicillin G in tammar wallabies were estimated to remain above mini­mum inhibitory concentrations (MIC) for Fn for only

8.2 hr and 8-10 hr, respectively, following IM adminis­tration of long-acting formulations (20 mg/kg and 30 mg/kg, respectively) (McLelland 2007). Hence, the efficacy of these dosages at standard frequencies (q 2-3 d) is questionable. However, clinical resolution has often been achieved with these dosing protocols, suggesting more favourable MIC profiles of key pathogens present, more favourable pharmacokinetics in compromised ani­mals (Kirkwood et al. 1988; McLelland et al. 2011) or that physical manipulation was the critical intervention.

Increasing the dosage of long-acting formulations can increase the maximum concentration (Cl and pro­long the half-life (T₁∕₂) (Papich et al. 1994). Benzathine (Kane et al. 2017) and/or procaine penicillin G, and long- acting oxytetracycline, at 2- to 3-fold the label dosages can be administered to macropods without apparent adverse effect. For cases of osteomyelitis or systemically disseminated infection, more frequent administration of short-acting antibiotics is more likely to achieve clini­cally effective antibiosis than these long-acting prepara­tions. Ceftiofur crystalline free acid (6.6 mg/kg q 4 d) appears to be an effective long-acting broad-spectrum antibiotic in macropods and has been used as part of suc­cessful treatment protocols (L Vogelnest pers. comm.) (Fig. 32.5).

The degree to which systemically administered antibi­otics penetrate into inflamed and necrotic periodontal tissues in macropods is unknown. Topical application of antibiotics/antiseptics directly affect infection in oral tis­sues. A bioadhesive chlorhexidine gel (Curasept®, Curaden Swiss, Marleston, SA) has been used as a compo­nent of successful multimodal treatment protocols (L Vogelnestpers. comm.). An orally applied varnish provid­ing sustained release of chlorhexidine has been used con­currently with systemic antibiosis in the successful treatment of MPPD (Bakal-Weiss et al. 2010). In humans, the varnish maintained significantly decreased plaque compared with controls for 4 d post-application (Fried­man et al. 1985). However, the relative contribution of this product in resolving MPPD lesions remains to be conclusively demonstrated and the ability of some orally applied products to reach the subgingival pocket where the disease is progressing is questionable. Persistent slow- release vehicles containing antimicrobials that specifi­cally target anaerobes should be investigated.

Antibiotic-impregnated beads have been used success­fully in advanced cases of osteomyelitis (Hartley and Sanderson 2003; Grifols et al.

The use of prebiotics and probiotics to positively manipulate oral flora has been proposed for humans (Marsh et al. 2015). Such preparations could prove benefi­cial for both treatment and prevention of MPPD and are worthy of investigation.

4.3. Supportive care

Stressors should be minimised. Treatment intensity should be balanced against patient tolerance. Behav­iour modifying drugs (see Chapter 9 and Appendix 4) can assist in managing stress associated with intensive treatment. Measures to reduce myopathy risk should be considered. Appropriate analgesia should be provided (see Appendix 4). Sufficient nutritional intake is essen­tial; gavage feeding at appropriate intervals may be required. Animals in managed care with few to no teeth can do well with appropriate feed management. Predisposing factors should be identified and addressed.

5.