Top 5 Times to Reconsider Antibiotic Prescriptions

Antibiotics are important for treatment of bacterial infections in dogs and cats, but use can lead to adverse effects and antimicrobial resistance. Prescribers should carefully consider whether antibiotic treatment is necessary based on the individual situation. Many conditions can be managed via supportive care and watchful waiting (ie, delayed antibiotic administration for conditions that may self-resolve). Communication with pet owners, including discussion of plans for supportive care and follow-up, is essential for maintaining a positive relationship, especially in cases in which owners expect a therapy that is not provided.

Following are the top situations in which antibiotics may seem necessary but are not, according to the author.

1. Feline Upper Respiratory Infections Without Systemic Illness

Acute clinical signs of sneezing, conjunctivitis, and ocular and nasal discharge in cats typically indicate a viral upper respiratory infection (feline herpesvirus [FHV-1] or feline calicivirus). Management of recurrent upper respiratory infections, whether known or presumed to be viral, typically involves stress reduction through environmental enrichment, feline synthetic pheromones, and routine preventive care. Despite management, FHV-1 can cause congestion, decreased appetite, and lethargy.

Watchful waiting is recommended if clinical signs last <10 days and no signs of systemic illness are present.¹ If nasal discharge is serous, secondary bacterial infection is unlikely. For opaque nasal discharge, color is unreliable in predicting whether a secondary bacterial infection is present.

All cats with FHV-1 should receive supportive care, including humidification of the air to loosen respiratory secretions (eg, running hot water in the shower with the cat in an enclosed bathroom, at-home nebulizers). Gentle cleaning of nasal and ocular secretions can also aid in comfort.

Appetite may be reduced because of decreased ability to smell. Offering warmed canned food or adding a highly aromatic treat can encourage eating. Unnecessary antibiotic administration can further decrease appetite because of possible GI upset and should therefore be avoided. Appetite stimulants (eg, mirtazapine) may also be considered.

Diagnostics (eg, feline upper respiratory disease PCR panel, imaging) and antibiotic therapy may be warranted if clinical signs persist >10 days, inappetence is refractory to supportive care, or there are signs of respiratory distress or systemic illness (eg, fever, lethargy).

2. Canine Infectious Respiratory Disease Complex Without Pneumonia

Canine infectious respiratory disease complex (CIRDC) results in an acute cough that may be accompanied by nasal discharge and can be caused by various viral and bacterial pathogens, sometimes in combination. Many cases are thought to be due to viral infection,¹ making antibiotic therapy unnecessary in otherwise healthy dogs.

Dogs with CIRDC and an acute-onset cough typically retain normal energy levels and appetite, and clinical signs often resolve without intervention within 10 days. Antibiotic therapy within the first 10 days of clinical illness should be reserved for dogs with fever, lethargy, and decreased appetite.¹ Most dogs recover in 1 to 2 weeks without antibiotic treatment,² although cough can persist for a month. If there is no evidence of a productive cough, antitussives may provide comfort.

3. Subclinical Bacteriuria

UTIs are defined by the presence of bacteriuria along with lower urinary tract signs (eg, hematuria, stranguria, pollakiuria). Presence of bacteria and WBCs in the urine without clinical signs of lower or upper urinary tract disease is suggestive of subclinical bacteriuria, regardless of the degree of pyuria or the colony-forming unit count of the bacterial culture.

Subclinical bacteriuria is common and found in up to 12% of healthy dogs, 13% of healthy cats, 8% to 30% of dogs with chronic kidney disease, and 16% of cats with chronic kidney disease.^3,4 Abstaining from treating patients without clinical signs despite positive urine cultures does not affect morbidity or mortality rates.^5,6 In humans, subclinical bacteriuria, even in the presence of significant pyuria, is not treated unless the patient is pregnant or planning to undergo urogenital surgery.⁷ Subclinical bacteriuria is not associated with survival rates, including in patients with comorbidities (eg, paralysis).⁸

4. Acute Diarrhea

Although acute diarrhea in cats and dogs is typically self-limiting, antibiotics (eg, metronidazole) are frequently administered, despite evidence questioning usefulness and evidence that antibiotics can cause dysbiosis in healthy dogs.^9-12

Acute diarrhea in dogs does not resolve more quickly with metronidazole administration compared with placebo or probiotics, and a highly digestible diet may be more effective than dietary management plus metronidazole for resolving acute large intestinal diarrhea.^9-11 Metronidazole for treatment of acute diarrhea is thus not supported. Metronidazole use in healthy dogs and dogs with acute colitis can cause dysbiosis, which can last at least 4 weeks in some dogs.¹¹

Antibiotics are not typically needed in patients with acute diarrhea, including acute hemorrhagic diarrhea syndrome (AHDS). In dogs with mild or moderate AHDS, treatment with amoxicillin/clavulanate does not alter the course of disease or recovery compared with placebo.¹³ Dogs with a neutrophilic left shift can recover without antibiotic treatment.¹⁴ Antibiotics should be reserved for dogs with a degenerative left shift or evidence of sepsis and, in severe cases, to treat sepsis or prevent the systemic consequences of bacterial translocation and bacteremia.

5. Lyme Seropositivity in Healthy Dogs

Seroprevalence of anti-Borrelia burgdorferi antibodies may be high in endemic areas; however, only ≈5% of seropositive dogs develop clinical signs of disease, and development of Lyme nephritis is rare.^15,16 Although treatment of dogs seropositive for anti-B burgdorferi antibodies can be controversial, consensus guidelines generally do not recommend treatment of subclinical and nonproteinuric seropositive dogs.¹⁷ Positive results on serologic tests (eg, point-of-care ELISA, quantitative titers performed at reference laboratories) are not predictive of development of clinical disease, and there is no evidence that treatment of subclinical dogs decreases risk for illness. Doxycycline, the treatment of choice for Lyme disease, is associated with known risks, including GI upset and hepatotoxicity.