Managing Persistent Cough in Dogs and Cats: From Conventional Therapy to Emerging Options

Persistent cough in dogs and cats may require more than treatment of the primary disease. When coughing continues despite appropriate management, the treatment strategy can include anti-inflammatory therapy, bronchodilation, mucus management, environmental control, and selected antitussive approaches. 

Treat the Underlying Disease First 

Management depends on the cause of the cough. Congestive heart failure may require diuretics and vasodilators, while pulmonary hypertension secondary to chronic bronchitis may be managed with a phosphodiesterase inhibitor such as sildenafil or pimobendan. Pulmonary thromboembolism requires anticoagulation, while infectious causes may require antibiotics or antifungals. Neoplasia or lung lobe torsion may require surgical treatment^[1]. 

When the primary disease is appropriately addressed, but chronic coughing continues, additional treatment may be required to reduce airway inflammation, bronchoconstriction, or excessive secretions. 

Control Airway Inflammation 

Glucocorticoids are used in dogs and cats with bronchial disease, tracheal collapse, and inflammatory respiratory disease^[1],[2]. 

They can reduce bronchoconstriction, airway oedema, mucus production, and eosinophil chemotaxis, helping improve cough and exercise tolerance^[1]. 

Treatment should begin at a dose sufficient to control clinical signs and then be reduced to the lowest effective dose. Every-other-day long-term treatment is preferred when possible, to reduce adverse effects and preserve hypothalamic-pituitary-adrenal axis function^[1]. 

Inhaled fluticasone may reduce systemic adverse effects compared with systemic glucocorticoids, although it requires a facemask and spacer and is more expensive^[1]. 

Glucocorticoids require particular caution when infection, gastrointestinal ulceration, hyperadrenocorticism, diabetes, hypertension, congestive heart failure, or renal disease is present. A definitive diagnosis should be pursued before treatment because glucocorticoids can mask underlying disease^[1]. 

Improve Airway Function and Secretion Clearance 

Bronchodilators can be useful for intrathoracic airway collapse, small airway disease, bronchomalacia, and increased expiratory effort, but they do not affect the larger airways or trachea^[1]. 

Methylxanthines such as theophylline and aminophylline, along with beta agonists such as terbutaline and albuterol, are used for bronchodilation^[1]. 

When airway secretions become viscous or inspissated and are not adequately cleared by mucociliary transport, mucokinetics and expectorants may be considered^[1]. 

Acetylcysteine can break disulfide bonds and also has antioxidant and anti-inflammatory properties. Nebulized acetylcysteine can irritate the airways and induce bronchospasm in cats, so its use requires caution^[1],[3]. 

Nebulization and coupage can assist mucus clearance in lower airway disease. Saline or sterile water can be nebulized, while selected medications can be delivered directly to the lower respiratory tract^[4]. 

Reduce Environmental Triggers^[1] 

Environmental management can complement medical treatment. 

Dogs and cats with chronic cough should be protected from indoor cigarette smoke, air fresheners, incense, perfumes, and other noxious fumes. Obesity should be controlled, and a harness rather than a neck collar can be used in dogs with tracheal collapse or tracheal sensitivity. 

Avoiding infectious exposure, maintaining a cool environment, and minimizing excitement, barking, and anxiety can also help reduce coughing. 

Where Are Newer Options Heading? 

Persistent chronic cough has prompted interest in treatments that target the sensory pathways involved in the cough reflex. 

Neuromodulators such as gabapentin, pregabalin, and amitriptyline have been associated with improvements in quality of life, cough severity, and symptoms in chronic idiopathic cough, although optimal dosing, treatment duration, relapse, and patient selection remain areas requiring further investigation^[5]. 

Maropitant, an NK1 receptor antagonist, has also been proposed as a potential antitussive because of its effects on substance P pathways, although findings regarding the precise role of substance P in cough remain conflicting^[1],[6],[7]. 

Other emerging approaches include targeting TRPV1 and TRPA1 channels involved in sensory airway responses. These pathways are being investigated as potential targets for reducing airway hypersensitivity and cough^{[1],[8],[9],[10]}. 

These approaches remain investigational rather than established routine treatments. 

A Multidimensional Approach 

Managing persistent cough in dogs and cats may require several strategies at once: controlling the underlying disease, reducing airway inflammation, improving secretion clearance, addressing environmental triggers, and selectively controlling excessive coughing. 

The newer therapies are moving toward the sensory mechanisms underlying chronic cough, but their clinical role remains under investigation. For now, treatment continues to centre on identifying and managing the primary disease while tailoring supportive therapy to the type and severity of cough.

References:

1. Hsieh BM, Beets AK. Coughing in small animal patients. Frontiers in Veterinary Science. 2020 Jan 21;6:513. https://www.frontiersin.org/journals/veterinary-science/articles/10.3389/fvets.2019.00513/pdf
2. Nemanic S, London CA, Wisner ER. Comparison of thoracic radiographs and single breath-hold helical CT for detection of pulmonary nodules in dogs with metastatic neoplasia. Journal of veterinary internal medicine. 2006 May;20(3):508-15. https://onlinelibrary.wiley.com/doi/pdfdirect/10.1111/j.1939-1676.2006.tb02889.x
3. Rogers DF. Mucoactive agents for airway mucus hypersecretory diseases. Respiratory Care. 2007 Sep;52(9):1176-97. https://www.liebertpub.com/doi/pdf/10.4187/respcare.07521176
4. Rozanski EA, Bach JF, Shaw SP. Advances in respiratory therapy. Veterinary Clinics of North America: Small Animal Practice. 2007 Sep 1;37(5):963-74. https://cmapspublic.ihmc.us/rid=1MDWCVCX9-1W8BM9C-5611/Advances_in_Respiratory_Therapy.pdf
5. Cohen SM, Misono S. Use of specific neuromodulators in the treatment of chronic, idiopathic cough: a systematic review. Otolaryngology--Head and Neck Surgery. 2013 Mar;148(3):374-82. https://pmc.ncbi.nlm.nih.gov/articles/PMC5813813/pdf/nihms887282.pdf
6. Najafian B, Shohrati M, Harandi AA, Mahyar S, Khaheshi I, Ghanei M. Serum level of substance P in patients with lung injuries due to sulfur mustard. Advanced biomedical research. 2014 Jun 25;3:137. https://pmc.ncbi.nlm.nih.gov/articles/PMC4139982/pdf/ABR-3-137.pdf
7. Otsuka K, Niimi A, Matsumoto H, Ito I, Yamaguchi M, Matsuoka H, Jinnai M, Oguma T, Takeda T, Nakaji H, Chin K. Plasma substance P levels in patients with persistent cough. Respiration. 2011 Aug 12;82(5):431-8. https://www.academia.edu/download/76798017/330419.pdf
8. Birrell PM, Bonvini BS, Dubuis PE, Maher PS, Wortley PM, Grace PM, Raemdonck PK, Adcock PJ, Belvisi PM. Tiotropium modulates transient receptor potential V1 (TRPV1) in airway sensory nerves: A beneficial off-target effect?⋆. Journal of allergy and clinical immunology. 2014 Mar 1;133(3):679-87. https://www.sciencedirect.com/science/article/pii/S0091674913018563
9. Delescluse I, Mace H, Adcock JJ. Inhibition of airway hyper‐responsiveness by TRPV1 antagonists (SB‐705498 and PF‐04065463) in the unanaesthetized, ovalbumin‐sensitized guinea pig. British journal of pharmacology. 2012 Jul;166(6):1822-32. https://bpspubs.onlinelibrary.wiley.com/doi/pdf/10.1111/j.1476-5381.2012.01891.x
10. Mukhopadhyay I, Kulkarni A, Aranake S, Karnik P, Shetty M, Thorat S, Ghosh I, Wale D, Bhosale V, Khairatkar-Joshi N. Transient receptor potential ankyrin 1 receptor activation in vitro and in vivo by pro-tussive agents: GRC 17536 as a promising anti-tussive therapeutic. PloS one. 2014 May 12;9(5):e97005. https://journals.plos.org/plosone/article/file?id=10.1371/journal.pone.0097005&type=printable