Canine Recurrent Pyoderma--Finding the Causes & Successful Management

Introduction and General Information

Pyoderma

Pyoderma is second only to flea allergy dermatitis in North America, among the most common diseases seen in small animal practice worldwide.

Recurrent Pyoderma

Refers to bacterial infections that respond completely to appropriate systemic and topical antibacterial therapy leaving the dog apparently normal between episodes of infection. Many dogs with pyoderma respond appropriately to initial therapy and pyoderma does not reoccur. An unknown percentage of dogs with pyoderma recrudesce after apparent recovery. Recurrent superficial pyoderma is much more common than recurrent deep pyoderma, many apparent cases of recurrent deep pyoderma are cases where complete cure was never achieved. Idiopathic recurrent pyoderma--appropriate diagnostic tests have failed to reveal an underlying cause.

Underlying Causes of Recurrent Pyoderma

DeBoer has produced the most logical subdivisions. This listing has been adapted from his classification:

1. Persistent underlying skin disease

2. Bacterial hypersensitivity

3. Immunodeficiency

4. Resistant strains of Staphylococcus intermedius (or other Staphylococcus--S. schleiferi, S. aureus)

5. Non-staphylococcal pyoderma

Bacterial Hypersensitivity

The concept of 'bacterial hypersensitivity' remains controversial. It is likely that some of the severe, self-perpetuating inflammation and pruritus seen with pyoderma is due to hypersensitivity to bacterial products. Fadok has speculated that hypersensitivity to super-antigens may play a role in severe inflammation seen with some canine pyoderma. Morales, Schultz & DeBoer substantiated an association between anti-staphylococcal antibodies and pyoderma subgroups.

Immunodeficiency

Despite its attractiveness as a concept, immunodeficiency is a rare cause of recurrent pyoderma.

Resistant Strains of Staphylococcus spp.

Multi-resistant strains of S. intermedius are uncommon but over-diagnosed. S. intermedius maintains a propensity not to develop resistance to cephalosporins, beta lactamase-resistant penicillins and fluoroquinolones. There has been little change in antibiotic susceptibility patterns in much of the world over the past two decades until recently.

Newer Data on Staphylococcal Infections

Staphylococcal infections in domestic animals have become more problematic during the past 5 years. For many years, veterinarians concentrated on managing infections caused by S. intermedius in dogs, cats, horses. S. schleiferi (coagulase positive or negative) was viewed as an uncommon pathogen of dogs and humans. S. aureus was relegated to discussions about humans. Currently, S. aureus is being identified with increasing frequency as a pathogen in domestic animals and as a cause of skin disease.

Methicillin resistance (MR) is being recognized with increased frequency in veterinary medicine and will have substantial impact on how we manage staphylococcal skin disease in the future. Methicillin resistance is reported in S. aureus (hospital or community acquired HA-MRSA & CA-MRSA), S. intermedius (MRSI), & S. schleiferi (MRSS).

Empirical treatment of staphylococcal infection has been the norm in dogs. Only refractory cases have been cultured routinely. This may have lead to lack of identification of MR. In human medicine, the use of fluoroquinolones may initiate enhanced MR in S. aureus. In work done in Philadelphia by Morris, MR in S. intermedius is increasing. The most reliable antibiotics against MRSI in this work were chloramphenicol and potentiated sulfonamides.

MR in staphylococci causing skin disease in domestic animals is still uncommon. However, this may be changing. Large urban centers with multiple medical schools may experience more antimicrobial pressure. This may be reflected in the data of Morris in Philadelphia. A similar phenomenon may be occurring in other urban centers globally.

We may be reaching the day when bacterial culture and sensitivity should be recommended for pyoderma that have not responded to appropriate initial empirical therapy.

Why are 'Resistant' Strains Over-diagnosed?

1. Skin perfusion--less than ideal for establishing adequate dosages of antibiotics, in comparison to other body tissues.

2. Dosages of antibiotics--largely empirical until recent years.

3. Deep pyoderma--sequestered foci of infection, foreign body granulomatous response, antibiotic inactivation by inflammatory products compromise effective antibiotic dosing.

4. Antibiotics where dosing can safely be increased in deep pyoderma--cephalosporins, fluoroquinolones, oxacillin, clavulanic acid-potentiated amoxicillin.

Non-Staphylococcal Pyoderma

This is uncommon to rare as a primary event. Culture of organisms other than S. intermedius commonly indicates secondary invaders or environmental contamination of the culture. Occasionally, infections are caused by Pseudomonas, Proteus, Escherichia coli, Enterobacter.

Post-grooming furunculosis is associated with diluted, contaminated shampoos (self-serve dog washing facilities), follicular trauma? P. aeruginosa may be most common.

Persistent Underlying Skin Disease

This is the most commonly documented cause of canine recurrent pyoderma. Diseases include non-parasitic allergic diseases (topic dermatitis, food allergy), parasitic allergic diseases (flea allergy, scabies, cheyletiellosis), demodicosis, endocrine diseases (hypothyroidism, hyperglucocorticoidism (primary or iatrogenic), diseases of cornification--(seborrhea), other infectious skin diseases, genodermatoses (especially hereditary dermatoses involving defects in hair follicles), occult neoplasia (solar-induced squamous cell carcinoma & other tumors), and immunodeficiency--(congenital, acquired).

Pruritus and Recurrent Pyoderma

The presence or absence of pruritus is a key feature in differentiating persistent underlying skin diseases. Common pruritic, persistent underlying skin diseases are atopic dermatitis, food allergy, flea allergy dermatitis, cheyletiellosis, sarcoptic acariasis, and primary cornification defects.

Approach to Recurrent Pyoderma

1. Aggressively pursue the diagnosis of possible persistent underlying skin diseases.

2. Manage the underlying skin diseases--long-term, consistent (in our clinic, canine atopic dermatitis is the most commonly diagnosed underlying skin disease).

3. Manage the episode of recurrent pyoderma and prevent episodes or diminish frequency of recurrence.

Goals of Long-term Management

1. Establish realistic owner expectations

2. Successfully treat pyoderma, maintaining therapy for long enough to ensure cure:

a. Superficial pyoderma--minimum of 3 weeks, at least 1 week beyond clinical cure.

b. Deep pyoderma--minimum of 6 weeks, at least 2 weeks beyond apparent cure.

Prevent or Diminish Frequency of Recurrence--An Overview

Topical antibacterial shampoo therapy should be used adjunctively in all recurrent pyoderma, continue indefinitely in idiopathic cases.

Immunomodulatory therapy using adjunctive, killed bacterial preparations or non-bacterial immunostimulants is attempted in dogs with confirmed or suspected defects of the immune system or in dogs with idiopathic recurrent pyoderma.

Extended regimens of antibiotic therapy are a last resort.

Topical Antibacterial Shampoo Therapy

Rationale--decrease surface bacteria, limit re-colonization, diminish frequency of recurrence?

Active agents--chlorhexidine, benzoyl peroxide, benzoyl peroxide and sulfur, triclosan, ethyl lactate.

Frequency--2x / week, 15 minutes contact time.

Improvement in patient attitude and owner encouragement.

Immunomodulatory Therapy

Rationale--stimulate immune surveillance, alter response to bacterial allergen, diminish recurrence, (controversial).

Staphage LysateR--SPL--(Delmont Laboratories, Swarthmore, Pennsylvania, USA)--S. aureus, serotypes I & III, protein A.

Extended Antibiotic Regimens

Diminish recurrence by preventing re-infection.

Dosing--3 consecutive days/week (full daily dose).

Antibiotic choices--cephalexin, cefpodoxime, enrofloxacin, marbofloxacin, other fluoroquinolones, clavulanate-potentiated amoxicillin, oxacillin.

Extended antibiotic regimens--consider as a last resort.

Extended Antibiotic Regimens--Antibiotic Choices

Underlined antibiotics are viewed as good choices for extended regimens

1. Narrow spectrum antibiotics:

a. Isoxazolyl penicillins--oxacillin, cloxacillin, dicloxacillin, nafcillin

b. Macrolide group--erythromycin, tylosin

c. Lincosamide group--lincomycin, clindamycin

2. Broad spectrum antibiotics:

a. Trimethoprim & ormetoprim-potentiated sulfonamides

b. Aminopenicillin & B-lactamase inhibitor--clavulanic acid-potentiated amoxicillin

3. First generation (group 2) oral cephalosporins--(cephalexin, cefadroxil, cephradine)

4. Third generation (group 5) oral cephalosporins--(cefpodoxime)

5. Fluoroquinolones--enrofloxacin, marbofloxacin

Compliance

Client education increases compliance--extended regimens with once a day dosing may lead to greater compliance.

Treatment Failure in Recurrent Pyoderma

Underlying causes--not identified or cannot be managed.

Inadequate duration of curative antibiotic therapy before switching to extended regimens.

Inadequate owner compliance.

Antibiotic resistance

References

1. DeBoer DJ. Management of chronic and recurrent pyoderma in the dog, in Bonagura JD (ed): Kirk's Current Veterinary Therapy XII. Philadelphia, WB Saunders, 1995, pp 611-617.

2. Ihrke PJ. Bacterial infections of the skin. In: Greene CE (ed): Infectious Diseases of the Dog and Cat, Third Edition, Philadelphia, WB Saunders Co, 2006, 807-815.

3. Carlotti DN, Jasmin P, Gardey L, Sanquer A. Evaluation of cephalexin intermittent therapy (weekend therapy) in the control of recurrent idiopathic pyoderma in dogs: a randomized double-blinded, placebo-controlled study. Vet Dermatol 2004;15s: 8-9.

4. Gross TL, Ihrke PJ, Walder EJ, Affolter VK. Skin Diseases of the Dog and Cat: Clinical and Histopathologic Diagnosis. Blackwell, Oxford, pp 222-225, 4-9, 406-410, 420-435, 2005.

5. Morris DO, Rook KA, Shofer FS, Rankin SC. Screening of S. aureus, S. intermedius, and S. schleiferi isolates obtained from small companion animals for antimicrobial resistance: Vet Dermatol 17: 332-337, 2006.

Speaker Information
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Peter J Ihrke, VMD, DACVD
School of Veterinary Medicine
University of California
Davis, California, USA

Update on Therapy of Canine Pyoderma

Introduction

Canine pyoderma is a complex of diseases involving bacterial infection at different levels of the skin (Table 1) and requiring different approaches to therapy. These diseases are nearly always secondary and so it is important to identify underlying factors. Commonly these are allergies but endocrinopathy, immunodeficiency, ectoparasitic infestation, follicular dysplasia and breed predisposition may be involved. Diagnosis of underlying conditions may not be easy. Treatment during the diagnostic phase should be designed to advance diagnosis and avoid camouflaging diagnostic clinical signs. Antibiotic therapy is a good diagnostic strategy as it eliminates pyoderma and helps expose underlying conditions.

This presentation assumes that a diagnosis has been made and deals with current approaches to the treatment of the different forms of infection. Treatment of underlying causes is not covered.

Table 1. Classification of canine pyoderma.

Surface pyoderma

Acute moist dermatitis

Skin fold pyoderma

Microbial overgrowth*

Superficial pyoderma

Impetigo ("puppy pyoderma")

Mucocutaneous pyoderma

Superficial spreading pyoderma

Superficial folliculitis

Deep pyoderma

Muzzle folliculitis & furunculosis

Localised deep pyodermas (nasal, pedal & pressure point pyodermas, pyotraumatic folliculitis & furunculosis)

Generalised deep pyoderma

Bacterial granulomas

*Not strictly pyoderma. Commonly both pathogenic staphylococci and Malassezia are present.

Surface Pyoderma

Acute Moist Dermatitis. Prevention of further trauma is essential and will sometimes allow healing without further therapy. Ensure that there is no underlying folliculitis or furunculosis. Because the epidermal damage is a consequence of trauma, healing is rapid. However, lesions are often painful and topical therapy, requiring direct contact with skin, can be hazardous. Topical antibiotic and steroid gels or creams are effective but spraying with a soothing, antimicrobial, astringent preparation has been shown to be as effective1 and is likely to be less hazardous. Lesions should be substantially healed in 7-10 days. Where there is marked pruritus, systemic glucocorticoids may be required.

Skin Fold Pyoderma. Ideally, folds are removed surgically. If surgery is not feasible, measures to render the microenvironment within the fold inhospitable to bacteria and yeasts are required. Cleansing every 2-3 days with an antimicrobial shampoo is effective. Benzoyl peroxide, chlorhexidine, and chlorhexidine and miconazole are effective. Chlorhexidine is quite unstable and so it is advisable to select well-formulated preparations with published efficacy against both bacteria and Malassezia.2 (Lloyd 1999) Benzoyl peroxide must used with care as animals may develop sensitivity and it can be irritant. Ethyl lactate may be effective in milder cases and has low irritancy. Intervals between shampooing may be extended by the use of antimicrobial creams and gels. Spraying with a soothing, antimicrobial, astringent preparation may also be effective.

Superficial Pyoderma

Impetigo normally responds to antimicrobial shampoos. Use on two or three occasions over a period of 7-10 days should be effective in uncomplicated cases. Spontaneous resolution commonly occurs.

Mucocutaneous Pyoderma may respond to treatment with antibacterial shampoos, as described above, followed by the use of antibacterial ointment, such as mupirocin. Daily treatment for two weeks and then once or twice a week may be effective. Following resolution, the disease may remain in abeyance but commonly repeated treatment is required. With deeper or more extensive infection, or if topical treatment is difficult, systemic antibiotic is required. Treatment for 4 weeks or more may be necessary. If not successful, further diagnostic procedures, including biopsy, are required.

Superficial Folliculitis and Superficial Spreading Pyoderma. Normally systemic antibiotic therapy is used. Bacteriostatic antibiotics are effective but bactericides are preferable. Treatment for at least one week beyond clinical cure is advisable. Recovery may be promoted by use of antibacterial shampoos containing chlorhexidine or benzoyl peroxide, or in milder cases ethyl lactate, which aid removal of crusts and reduce surface bacterial populations.2,3 Mild superficial pyoderma can be treated with such shampoos without systemic antibiotic but this is labour-intensive; shampooing every 2-3 days is required. Once lesion resolution occurs, shampooing can be reduced to once or twice a week; in winter weekly to monthly shampooing may be sufficient to maintain remission.

Where there is recurrent infection and underlying causes cannot be identified or controlled, long-term treatment options need to be considered. Regular shampooing with antibacterial shampoo may give control. Otherwise, the main options are pulse therapy with antibiotics and staphylococcal vaccination. Vaccination is a better choice. Well-prepared autogenous vaccines (bacterins) are effective in about 50% of cases; responding dogs do not need other therapy.4 An American bacterial lysate prepared from S. aureus, has also been shown to reduce the frequency of folliculitis and decrease the need for repeated antibiotic therapy.5 Pulse or continual low dose therapy6 should be a last resort as it may promote development of antibiotic resistance, although recent evidence indicates that this risk may be low.

In view of the fact that the causative pathogen may be harboured on the mucosae, particularly of the upper respiratory tract and anus, some clinicians have used topical antibiotic to treat the nasal and or anal mucosae. Experimental studies have shown that S. intermedius populations can be eliminated by this method using fusidic acid.7 Anecdotally, this has helped in some cases of recurrent pyoderma.

Deep Pyoderma

When deep infection occurs, there are local factors causing skin damage and more serious deficiencies in the immune system of the affected animal. If these can be resolved, recovery should be complete. Determined efforts to identify the underlying factors should be made. Demodicosis is a common cause.

With discharging lesions, antimicrobial washes and soaks are useful to remove pus and debris, and may accelerate recovery. Clipping is helpful, enables the extent of lesions to be demonstrated and can be useful in persuading clients to comply with treatment. Prolonged systemic antibiotic treatment with bactericidal antibiotic is necessary and must continue for at least two weeks beyond clinical cure. Where lesions are in areas with poor blood supply or large granulomatous lesions, fluoroquinolones, which penetrate well, are particularly useful. On rare occasions it may be necessary to use unusual antibiotics to achieve penetration, such as rifampicin.

In some cases, unusual organisms such as actinomycetes or mycobacteria are involved, and there may be concurrent infection with fungi. Careful diagnostic procedures, including discussion with the laboratory concerned, may be required as routine methods may not be effective.

Choice of Antibiotics and Dosage

Although antibiotics can be selected empirically, where recurrent infection occurs or there is a lack of response, microbiological culture and sensitivity should be carried out.8,9 Ensure that you use a reliable laboratory and question unusual results e.g., very broad resistance in an organism identified as S. intermedius; this could turn out to be a methicillin-resistant S. aureus or S. schleiferi.10,11 Remember that several different strains of pathogenic staphylococci may be present on a single animal. Thus a single sensitivity test may not give the full picture. Failure of a particular antibiotic may mean you have only eliminated part of the causative bacterial population. If in doubt, always retest. Ensure your sample contains material from deep within the lesions; biopsy may be necessary for this.

Generally, manufacturer's recommended dose rates will be effective. Occasionally you will need to use higher doses to achieve effective levels of antibiotic within lesions or to overcome low level resistance. The range of antibiotics commonly used in veterinary dermatology and their properties and use are reviewed in a special issue of Veterinary Dermatology published in 1999, which is still relevant and provides excellent summaries.12

References

1. Ascher F, Madin F, Guaguere E et al. Intérêt d'une solution topique non antibiocorticoide dans le traitement de la dermatite pyotraumatique du chien. Pratique Médicale et Chirurgicale de L'Animal de Compagnie. 1995; 30:345-354.

2. Lloyd DH, Lamport AI. Activity of chlorhexidine shampoos in vitro against Staphylococcus intermedius, Pseudomonas aeruginosa and Malassezia pachydermatis. Veterinary Record 1999; 144: 536-537.

3. De Jaham c. Effects of an ethyl lactate shampoo in conjunction with a systemic antibiotic in the treatment of canine superficial bacterial pyoderma in an open-label, non placebo-controlled study. Veterinary Therapeutics 2003; 4: 94-100.

4. Curtis CF, Lamport AI, Lloyd DH. Blinded, controlled study to investigate the efficacy of a staphylococcal autogenous bacterin for the control of canine idiopathic recurrent pyoderma. Proceedings of the 16th Annual Congress of the ESVD-ECVD, Helsinki, Finland, August 1999. p. 148.

5. Deboer DJ, Moriello KA, Thomas CB, et al. Evaluation of a commercial staphylococcal bacterin for management of idiopathic recurrent pyoderma in dogs. American Journal of Veterinary Research 1990; 51: 636-639.

6. Carlotti DN, Jasmin P, L. Gardey L, Sanquer A. (2004): Evaluation of cephalexin intermittent therapy (weekend therapy) in the control of recurrent idiopathic pyoderma in dogs: a randomized, double-blinded, placebo-controlled study. Veterinary Dermatology 2004; 15 ( s1): 7-8.

7. Saijonmaa-Koulumies L., Parsons E., Lloyd, DH. Elimination of Staphylococcus intermedius in healthy dogs by topical treatment with fusidic acid. Journal of Small Animal Practice 1998; 39: 341-7.

8. Holm BR, Petersson U, Morner A, et al. Antimicrobial resistance in staphylococci from canine pyoderma: a prospective study of first-time and recurrent cases in Sweden. Veterinary Record 2002; 151: 600-5.

9. Kruse H, Hofshagen M, Thoresen SI, et al. The antimicrobial susceptibility of Staphylococcus species isolated from canine dermatitis. Veterinary Research Communication 1996; 20: 205-14.

10. Loeffler A, Boag AK, Sung J, et al. Prevalence of methicillin-resistant Staphylococcus aureus among staff and pets in a small Animal referral hospital in the UK. Journal of Antimicrobial Chemotherapy 2005; 56: 692-7.

11. Frank, LA, Kania, SA, Hnilica, KA, et al. Isolation of Staphylococcus schleiferi from dogs with pyoderma. Journal of the American Veterinary Medical Association 2003; 222 (4); 451-4.

12. Special Issue on Antibiotics in Veterinary Dermatology. Veterinary Dermatology 1999; 10: 161-262.


Speaker Information
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David Lloyd
Royal Veterinary College
Hawkshead Campus
North Mymms, Hertfordshire , United Kingdom

Treatment of canine pyoderma

Treatment of canine pyoderma
Systemic (antibiotic) and topical therapy can be used in canine pyoderma.
1. Selection of antibiotics
The criteria for the choice of an antibiotic are as follows: appropriate kinetics and good cutaneous penetration, activity against Staphylococci, activity in pus and reactive tissues, bactericidal activity rather than bacteriostatic activity particularly in severe cases, easy administration (oral, q12h or q24h), absence of secondary effects, reasonable cost. The choice can be empirical, particularly in superficial pyoderma, after cytological examination of pus from an intact pustule which shows bacterial invasion. Bacteriology and sensitivity testing must be used in case of deep pyoderma, recurrent pyoderma, when cytology shows a complex flora with rods, and in case of empirical antibiotic therapy failure. They can be repeated during therapy.
2. Dosage and duration of treatment
Ideal doses must be used and duration of treatment must be long enough (a few weeks to several months depending of extension and depth of lesions, and always beyond clinical cure). Maintenance pulse treatment (e.g., 2 to 3 days a week) can be used in chronically relapsing pyoderma but it could theoretically select resistant strains as well as the use of subminimal doses. They are both used for economical reasons but the former is preferable.
3. Antibiotics useable in canine pyoderma
Antibiotics useful in canine pyoderma are included in the following table. They all have a good cutaneous diffusion (because of their liposolubility) and can be given orally, which is useful because of long therapeutic courses (ease of administration). They are all bactericidal except macrolides which are bacteriostatic.

Macrolides
narrow spectrum/Gram+
erythromycin : 30 to 50 mg/kg div. bid or tid
lincomycin : 40 to 50 mg/kg div. bid or tid
clindamycin : 5,5 to 11 mg/kg sid or div. Bid
tylosin : 40 mg/kg div. bid

Penicillins M
resistant to penicillinases
narrow spectrum/Gram+
oxacillin : 30 to 50 mg/kg div. bid
Penicillins A
potentiated by
clavulanic acid
resistant to penicillinases larger spectrum
amoxicillin-clavulanic acid : 25 mg/kg/div. bid

Cephalosporins
resistant to penicillinases
broad spectrum
cephalexin : 30 to 60 mg/kg div. Bid
cefadroxil : 44 to 70 mg/kg div. bid
Cephalosporin Presistant to penicillinases
narrow spectrum/Gram+
synergy with penicillins
and erythromycin
fusidic acid (the only one of this group) :
60 mg/kg div. tid

Sulfonamides-
Diaminopyrimidinesbroad spectrumtrimethoprim-sulfa : 30 mg (i.e., 5 mg trimethoprim)/kg sid or div. Bid
baquiloprim-sulfadimethoxine : 30 mg (i.e., 5mg
baquiloprim)/kg q.48h
ormetoprim-sulfadimethoxine : 30 mg (i.e., 5mg
ormetoprim)/kg sid after a single double dose
the first day

Fluoroquinolones
broad spectrum
excellent tissue
penetration
(not to be used in puppies of giant breeds)enrofloxacin : 5mg/kg sid of div. Bid
marbofloxacin : 2 mg/kg sid
difloxacin : 5 mg/kg sid
orbifloxacin : 2.5 mg/kg sid

Penicillin G (which is injectable) and A are sensitive to penicillinases. Aminoglycosides have a low cutaneous diffusion (they are hydrosoluble), are injectable and toxic. Chloramphenicol has a bad reputation in humans and the cat (haematologic toxicity). Tetracyclines have a very low activity against Staphylococci. These antibiotics are never or rarely used in canine pyoderma. Rifampicin is effective against Staphylococci but, as it is still used to treat human tuberculosis, it should be used when there is no other possibility (5 to 10 mg/kg SID). In addition, it should be then associated to a betalactamine to prevent the selection of resistant strains of Staphylococci. Mupirocine, a topically active bactericidal antibiotic, in a polyethylene glycol base is effective against Gram+ Cocci, is not systematically absorbed and is not chemically related to other antibiotics. It can be used in localized pyodermas (acne, pressure point pyoderma, interdigital pyoderma).
4. Associated treatments
Topical therapy is always beneficial in canine pyoderma, particularly in superficial staphylococcal disease. Clipping can be useful and is necessary in deep pyoderma such as cellulitis. The main useful topical products are chlorhexidine (lotion and/or shampoo), povidone-iodine (lotion and/or shampoo), benzoyl-peroxide (shampoo and eventually gel), ethyl-lactate (shampoo). They should be used frequently, e.g., once a day, at the beginning of therapy. Later, frequency of application may decrease. Each shampoo should be followed by the application of an appropriate humectant. Topical or systemic glucocorticoids should never be used in true canine pyoderma, even in case of pruritus, because they cause severe relapses ("rebound effect"). In contrast they can be used and are effective in pseudo-pyoderma (e.g., oral prednisolone: 1 mg/kg/day for pyotraumatic dermatitis and 2 mg/kg/day for juvenile cellulitis).

The Coughing Pet

Cough is a common problem in dogs but occurs less frequently in cats. Cough is caused by irritation of the throat, airways or the lungs. The main airway to the lungs known as the windpipe or trachea branches into smaller airways called bronchi which branch several more times as they travel to the deeper parts of the lung. (Anatomy of the lungs and airways: dog / cat)

There are many causes of cough. A thorough history and physical examination help the veterinarian decide which causes of cough are most likely in your pet and helps him or her decide which diagnostic tests to recommend and which therapies are most likely to be effective. Cough originating from the trachea may be stimulated by lightly squeezing the trachea. Cough due to heart disease may be accompanied by a murmur or abnormal heart rate or rhythm.

Your description of the nature of the cough, when the cough occurs, and if anything brings on coughing can be very helpful in pinpointing the cause of coughing in your pet. Some causes of cough result in difficulty breathing between coughing episodes whereas with other diseases, the pet breathes normally between coughing episodes. Some types of cough occur more commonly at night when the animal (and human family members) are trying to rest. Animals with heart failure, collapsing trachea and lung edema cough more at night than during the day.

Cough caused by tracheal irritation or tracheal collapse often occurs when the pet is excited or is tugging on its collar. Cough caused by heart disease may follow exercise or excitement. Cough due to tracheal collapse may be stimulated by drinking water. Coughing that occurs during or shortly after eating may be due to disease of the larynx or esophagus. The larynx normally closes when food is swallowed to prevent food from entering the trachea. If the larynx is diseased it may not close when food is swallowed resulting in food entering the trachea. Food may pool in an abnormally dilated esophagus. The food then may pass to the mouth and down the airways into the lungs causing pneumonia and cough.

Some coughs sound moist and others are harsh and dry. Moist coughs indicate the accumulation of fluid (water, blood or pus) in the airways or lungs. The environment and habits of the pet can influence which causes of cough are more likely. Dogs that hunt or spend time outdoors may inhale grasses, seeds or other foreign materials through the nose into the airways. In addition to causing coughing, foreign materials can travel down the airways and through the lung causing an infection with a large amount of pus to develop in the space surrounding the lung. This disease is called pyothorax. Animals that have exposure to other animals in a shelter or boarding facility are more likely to have an infectious cause for coughing. The region of the country in which you live or to which you and your pet have traveled, influences the likelihood of some diseases like heartworm disease and fungal infections of the lung (histoplasmosis, coccidiomycosis and blastomycosis). Heartworm disease occurs in both dogs and cats and is most common in parts of the country that have lots of mosquitoes.

The age and breed of the pet also influences what causes of cough are most likely. Young animals are more likely to develop a cough due to infections with bacteria or viruses. Young to middle aged cats may develop wheezing and cough due to asthma. Cats with asthma have sudden episodes of wheezing and coughing but are normal in between episodes. Middle aged to older, small breed dogs are more likely to have heart disease due to leaky valves. Middle aged to older, large breed dogs are more likely to develop paralysis of the larynx.

Tracheal collapse occurs most commonly in middle to aged overweight small breed dogs . Tracheal collapse is rare in cats. The cough is often described as sounding like a goose honking. Treatment for tracheal collapse includes weight reduction and intermittent use of cough suppressants and sedatives. Surgery can be performed in dogs with severe collapse that don't respond to weight reduction and cough suppressants but often surgery is not effective.

Kennel cough or infectious tracheobronchitis is caused by several infectious organisms, including bacteria and viruses. Vaccinations are not 100% protective against the agents of kennel cough. Coughing due to kennel cough usually becomes apparent within a few weeks of exposure of your dog to other dogs in a kennel or show environment. Kennel cough usually resolves itself without any treatment. If the cough is severe enough that the pet has difficulty sleeping or people in the house have difficulty sleeping, cough suppressants can be given to suppress the frequency of cough, allowing the pet and human members of the household to get rest while the disease runs its course. If the cough does not subside in a week to ten days, your pet should be evaluated for other diseases of the lungs or airways.

Cough can be caused by heart disease, which is diagnosed by a chest x-ray, an electrocardiogram which measures the electrical activity of the heart, and often by a heart ultrasound which allows the veterinarian to view the inside of the heart, including the valves and the thickness of the walls of the heart muscle. Heart disease may cause heart enlargement that puts pressure on the airways causing cough or the heart may fail and lead to edema of the lungs. (Anatomy of the dog / cat heart)

Allergies to particles in the air including dust, pollens, and smoke can cause allergic lung disease and coughing.

In older patients, lung cancer has to be considered. The lungs receives a large amount of blood that flows through the rest of the body. Lung cancers in dogs and cats most often originate from other organs and are transferred from those organs through the blood to the lung. Some cancers may be controllable with anticancer medication. Single lung tumors that originate within the lung may be surgically removed in some cases.Tests that may be recommended to identify the cause of a cough include a blood profile to screen multiple organs, a stool exam to look for parasites or their eggs that are coughed up and swallowed, chest x-rays or x-rays of the trachea. The larger airways can be examined using a flexible scope called a bronchoscope in a procedure called bronchcoscopy. Sterile fluid can be flushed into the airways to collect samples for culture or microscopic exam. Large foreign bodies in the airways can be removed by bronchoscopy. Specific tests may be performed if heart worm disease or an infectious cause for the cough are suspected.

Treatment of coughing patients depends upon the disease diagnosed and may include cough suppressants, antibiotics for bacterial infections, and steroids for allergic lung disease. Avoid self medicating your pet as the treatment for one cause of cough may be very wrong for the treatment of another type of cough.

Seizures in Dogs

A seizure is defined as a paroxysmal, transitory disturbance of brain function that has a sudden onset, ceases spontaneously, and has a tendency to recur. Epilepsy is a recurrent seizure disorder irrespective of cause. Generalized seizures affect the entire body. Most commonly, dogs will fall to the side, make paddling movements with the limbs, and often will urinate, salivate and defecate. Seizures usually last less than 90 seconds. Focal seizures remain localized to one body region. Seizures may start focal and then become generalized. Information about where the seizure activity begins is of value in localization of the seizure focus to one side of the brain. The seizure focus is the point in the brain from which the seizure begins.

After the veterinarian is convinced that a seizure disorder is present, the most important question to be answered is whether the seizure focus is the result of primary brain disease (intracranial), the result of a disturbance outside the brain (extracranial), or is occurring idiopathically (without obvious cause). Initially the causes for seizures, should be categorized into those secondary to an intracranial structural cause, an extracranial cause (metabolic), or an unknown cause (idiopathic).

Metabolic: Extracranial disease resulting in seizures can be separated into those causes arising within the dog itself (endogenous) for example due to liver disease, or those arising external to the dog (exogenous) such as toxins. There are numerous metabolic diseases that can result in seizures. These include low blood sugar (hypoglycemia), high blood sugar (hyperglycemia), liver disease, kidney disease, electrolyte disturbances, toxins (poisons), anemia, and heart and lung diseases.

Structural diseases which result in seizures include hydrocephalus, storage diseases, cancer (primary and secondary brain tumor), inflammatory diseases (infectious and non-infectious encephalitis), trauma (injury), and blood-vessel-based diseases. Primary brain cancers originate in the brain whereas secondary cancers develop when cells from cancers outside the brain are carried to the brain in the blood.

Idiopathic epilepsy is a seizure disorder without obvious cause. Idiopathic seizures (Idiopathic epilepsy) begins between 1 year and 4 years of age. Therefore, a dog that begins having seizures at 9 years of age does not have idiopathic epilepsy. Certain breeds of dogs are known or thought to have an increased incidence of idiopathic epilepsy such as beagles, Belgian Tervurens, German shepherds, keeshonds, and collies. High incidence breeds include the Saint Bernard, German shepherd, golden retriever, Irish setter, American cocker spaniel, Wire-haired fox terriers, Alaskan malamutes, Siberian Huskies, and miniature poodles.

To search for an extracranial cause for seizures, a metabolic evaluation is performed. The evaluation may include a complete physical examination, blood tests and sometimes x-rays. To search for a mass in the brain an imaging study (CT, MRI) is performed and sometimes cerebrospinal fluid (CSF) is collected. An electrical brain (EEG) evaluation is usually not very helpful, unless it is necessary to localize the seizure focus.

If an underlying disease can be found, then primary treatment for that disease may help to make the seizures stop. If the seizures are recurrent, anticonvulsant medications are often given. The choice of medication depends upon the characteristics of the individual animal's problem. Some of the more commonly used anticonvulsants are listed below. It is important to remember that once an anticonvulsant is initiated, it should not be changed without veterinary assistance. Most animals with idiopathic epilepsy will require anticonvulsant medication for the rest of their life.

Drugs Used to Treat Seizures

• Phenobarbital is a barbiturate. It is the most commonly used anticonvulsant. Toxicity signs include drowsiness/sedation, falling, increased drinking, urination and appetite. With high dosages or prolonged use, phenobarbital can cause damage to the liver. Paradoxically, some animals given phenobarbital may become restless and excitable. If this occurs, consult your veterinarian for assistance. For best results, this drug needs to be given consistently (every day) at least twice daily. This drug should not be altered without veterinary consultation
• Primidone is rapidly metabolized to phenobarbital and some other metabolites by the liver. Phenobarbital contributes 85% of the anticonvulsant activity due to its prolonged half-life. It seems to work no better than phenobarbital for most animals. Acute toxicity signs are similar to those of phenobarbital. Primidone may be more liver toxic than phenobarbital
• Phenytoin (Dilantin) is a commonly used anticonvulsant in people. Because it is metabolized differently in dogs, it not as effective in dogs. It also can be toxic to the liver. Phenytoin is toxic to cats and should not be used.
• Diazepam (Valium) is a benzodiazepine. It is a very effective anticonvulsant, but is metabolized very quickly in dogs, making it's effects short lasting. It is given in emergency situations because it works quickly. Acute toxicity includes drowsiness, lethargy, and depression.
• Potassium Bromide is used mostly as a secondary anticonvulsant in animals refractory to phenobarbital, however, can be used alone. Due to its lack of metabolism it is the ideal anticonvulsant for patients with liver disease. Acute toxicity includes vomiting, anorexia, constipation, sedation and incoordination.

Diarrhea in Dogs

Diarrhea is the passing of loose or liquid stool, more often than normal. Diarrhea can be caused by diseases of the small intestine, large intestine or by diseases of organs other than the intestinal tract. Your ability to answer questions about your pet's diet, habits, environment and specific details about the diarrhea can help the veterinarian narrow the list of possible causes, and to plan for specific tests to determine the cause of diarrhea. (Anatomy of the digestive system: dog / cat)

Small intestinal and large intestinal diarrhea have different causes, require different tests to diagnose and are treated differently. Small intestinal diseases result in a larger amount of stool passed with a mild increase in frequency; about 3 to 5 bowel movements per day. The pet doesn't strain or have difficulty passing stool. Animals with small intestinal disease may also vomit and lose weight. Excess gas production is sometimes seen and you may hear the rumbling of gas in the belly. If there is blood in the stool it is digested and black in color.

Disease of the large intestine including the colon and rectum cause the pet to pass small amounts of loose stool very often, usually more than 5 times daily. The pet strains to pass stool. If there is blood in the stool, it is red in color. The stool may be slimy with mucus. The pet does not usually vomit or lose weight with large bowel diarrhea. A sudden onset of small intestinal diarrhea may be caused by viruses including canine distemper, canine parvovirus, canine coronavirus, feline panleukopenia virus or feline coronavirus, in young, poorly vaccinated pets. Small intestinal diarrhea can be caused by bacteria such as salmonella, clostridia or campylobacter although these same bacteria can be found in the stool of normal dogs and cats.

Worms and giardia can cause small intestinal diarrhea, mostly in young animals. Foreign bodies including bones, sticks and other objects can pass through the stomach and get stuck in the intestine causing both diarrhea and vomiting. These same foreign materials may pass through the intestinal tract without getting stuck but may damage the lining of the intestinal tract causing diarrhea. Dietary indiscretion or a sudden change in diet can cause diarrhea with or without vomiting. Food allergies in dogs and cats can cause diarrhea, vomiting or itchy skin. Toxins including lead and insecticides can cause diarrhea usually with vomiting. Inflammatory bowel disease (IBD) occurs commonly in both dogs and cats. In IBD the walls of the intestine contain abnormal numbers of inflammatory cells which can be eosinophils, lymphocytes or plasma cells. The cause of IBD is not known but is suspected to be an allergic reaction to components of food, bacteria or parasites. IBD can be congenital in some breeds of dogs, for example Basenji dogs may develop a severe inflammatory bowel disease. Tumors of the intestine are another cause of diarrhea usually occurring in older pets. The tumor may be a single mass when the tumor is from the glands of the intestine (adenocarcinoma) and may be removed by surgery or the tumor may occur diffusely along the intestine. Lymphosarcoma occurs in both dogs and cats and can either be a single or multiple masses in the intestine or the abnormal lymphocytes may be spread through out the intestine. Lymphosarcoma is often responsive to anti-cancer drugs in cats but rarely responds to anti-cancer drugs in dogs.

In certain parts of the country small intestinal disease can be caused by fungal infections including histoplasmosis. Your veterinarian can discuss with you whether histoplasmosis is seen in your part of the country. Diseases outside the intestinal tract that may cause diarrhea include kidney failure, liver failure, pancreatic disease and hyperthyroidism in the cat. Severe inflammation of the pancreas (pancreatitis) can lead to damage of the pancreas and an inability to make enough enzymes to digest fat. This is called pancreatic insufficiency and causes diarrhea with a large volume of greasy stool. Pancreatic insufficiency can occur in young animals due to a congenital deficiency of pancreatic enzymes.

The cause of small intestinal diarrhea may be determined from blood tests, examination of the stool, x-rays or ultrasound of the abdomen or by endoscopy. Endoscopy is the technique of passing a flexible scope through the stomach into the upper intestine. Small biopsies of the lining of the intestine can be taken for microscopic evaluation. Endoscopy requires general anesthesia. A diagnosis of intestinal lymphosarcoma may be missed on endoscopy as the biopsies taken using endoscopy do not include the full thickness of the wall of the intestine and the cancerous cells may be deep in the wall of the intestine. A diagnosis in that case requires surgery in order to take a larger biopsy of the entire thickness of the intestine.

Dogs and cats with chronic small intestinal diarrhea will lose weight as they are unable to properly absorb nutrients and may develop edema of the legs or fluid accumulation in the belly or chest. A small protein, albumin may be lost in diarrhea. Albumin acts like a sponge to keep water in the blood vessels. When albumin is lost in the stool, blood albumin gets low and water leaks out of blood vessels to accumulate in other locations. Chronic diarrhea may cause the fur to look dull and brittle due to nutrient deficiencies. Acute small intestinal diarrhea can be managed by withholding food, but not water for 24 - 48 hours. If diarrhea stops, small amounts of a bland low-fat food are fed 3 to 6 times daily for a few days, with a gradual increase in the amount fed and a gradual transition to the pet's normal diet. Foods designed as intestinal diets usually contain rice as rice is more digestible than other grains. You are discouraged from administering over-the-counter diarrhea medications without first consulting a veterinarian. If the pet is active, not dehydrated and has been previously healthy, acute diarrhea can often be managed at home. Diarrhea that continues for more than a few days or is accompanied by depression or other signs is an indication to take your pet to a veterinarian.

Diarrhea of large intestinal origin can be caused by whipworms, polyps, inflammatory bowel disease, colonic ulcers or colonic cancer. Stress can cause large bowel diarrhea in excitable dogs. The diagnosis of large intestinal diarrhea is also made by blood tests and examination of the stool. A rectal examination using a gloved finger may provide some information about the cause of large bowel problems including rectal polyps and rectal cancer. Endoscopy to examine the large intestine is performed using a rigid or flexible scope passed up the rectum. Because the rectum is often very irritated, colon exams are usually performed under general anesthesia.

The treatment of large bowel diarrhea may be based on a specific diagnosis. Non specific treatment of large bowel diarrhea often includes a high fiber diet and sullfasalazine, an anti-inflammatory drug.

Vomoting in Dogs

What causes vomiting?
Vomiting is not a disease; rather, it is a symptom of many different diseases. Many cases of vomiting are self-limiting after a few days. Less commonly, vomiting may result from a serious illness, such as cancer. Even when vomiting is caused by mild illnesses, it may lead to death of the animal if treatment is not begun early enough to prevent severe fluid and nutrient losses.

How serious is vomiting in dogs?
Your veterinarian attempt to determine how sick the dog has become as a consequence of the vomiting. When the dog is systemically ill (i.e., more than one body system is involved), some of the following may be noted:
1. Diarrhea
2. Dehydration
3. Loss of appetite
4. Abdominal pain
5. High fever
6. Lethargy
7. Bloody vomiting

What types of tests are performed to find the cause?
If vomiting is associated with several of the above signs, your vet will perform a series of tests in the hope that a diagnosis may be made. When this can be done, more specific treatment may be initiated. Diagnostic tests may include radiography (x-rays) with or without barium, blood tests, biopsies of the stomach and intestinal tract, and exploratory abdominal surgery. Once the diagnosis is known, treatment may include special medications, diets, and/or surgery.

If your dog does not appear systemically ill from the vomiting, the cause may be less serious. Some of the minor causes of vomiting include stomach or intestinal viruses, stomach or intestinal parasites, and dietary indiscretions (such as eating garbage or other offensive or irritating materials). A minimum number of tests are performed to rule out certain parasites and infections. These cases may be treated with drugs to control the motility of the intestinal tract, drugs that relieve inflammation in the intestinal tract, and, often, a special diet for a few days. This approach allows the body's healing mechanisms to correct the problem. Usually improvement occurs within 2-4 days; if this does not occur, a change in medication or further tests are done to better understand the problem. Please keep your vet informed of lack of expected improvement so that he can manage the situation properly.