One of the exciting things about emergency veterinary medicine is that you never know what is going to come through the door, allowing several chances of playing the detective with regards to what is wrong with our “mute” furry family members. One of the more challenging presenting signs is the sudden onset of agitation or restlessness, which can be caused by many things: pain, fear, itching, inability to urinate, breathing issues, and something to always to consider: TOXINS.
Many things in our home can be toxic if ingested and each can cause a myriad of non-specific signs, and when our pets are acting agitated or restless, medication ingestion should always be considered. One of the more frequent medication exposures we treat is from antidepressant drugs, which can be commonly found in many of our homes. Small dogs can be most affected, as one dropped tablet can cause some pretty significant clinical signs.
What are the signs?
The signs are typically limited to the GI tract and nervous system, but can also involve the cardiovascular system in more severe cases.
Signs typically start within 1-2 hours after ingestion and can be delayed for several hours if extended release formulas are ingested. Restlessness and agitation are the most common presenting signs that I see, but signs can also include vomiting, diarrhea, seizures, fever, tremors, sensitivity to sounds and noises, depression, dilated pupils, vocalization, blindness, drooling, difficulty breathing, difficulty walking, disorientation, coma, and rarely death. I have personally only treated dogs for this toxicity, but (non-discriminating) cats have been known to ingest these medications, and have signs similar to that of dogs.
Commonly used medications and their level of toxicity:
High Toxicity Levels:
- Amitriptyline (Elavil®)
- Clomipramine (Clomicalm®, Anafranil®)
- Dexfenfluramine (Redux®)
- Fenfluramine (Ponderal®)
- Fluoxetine (Prozac®)
- Fluvoxamine (Luvox®)
- Isocarboxazid (Marplan®)
- MDMA (methylenedioxymethamphetamine)
- Moclobemide (Manerix®)
- Paroxetine (Paxil®)
- Phenelzine (Nardil®)
- Selegiline (Anipryl®, Eldepryl®)
- Sertraline (Zoloft®)
- Tranylcypromine (Parnate®)
- Venlafaxine (Effexor®)
Medium Toxicity Levels:
- Buspirone (BuSpar®)
- Desipramine (Norpramin®)
- Doxepin (Adapin®, Sinequan®)
- LSD (lysergic acid diethylamide)
- Nortriptyline (Pamelor®)
- Trazodone (Desyrel®)
Low Toxicity Level:
- Bromocriptine (Parlodel®)
- Bupropion (Wellbutrin®, Zyban®)
- Carbamazepine (Tegretol®)
- Mirtazapine (Remeron®)
- Nefazodone (Serzone®)
- Pentazocine (Talwin®)
- Pergolide (Permax®)
- Tramadol (Ultram®)
How is it diagnosed?
Diagnosis is based on possible exposure to these medications and presenting signs. Most of the dogs I have seen come in panting, tremoring and continue to move around as if they are uncomfortable or just can’t figure out what they want. The good news here is that the treatments are very safe and I typically see a very fast response in the patients that receive timely care.
The most important thing to help with diagnosis is letting your veterinarian know if there are any medications in the home — even if you think it is “impossible” for them to get into. Dogs are very good at getting into things, and I would have to say that the majority of cases I treat (for any toxin) includes the comment, “there is no way he can get into that!” Another thing to consider is that a dropped pill may have happened months and month ago, and your pet just happened to have found it that day.
What is the treatment?
Treatment is typically symptomatic and supportive. Vomiting can be induced if your pet is not too sedate; if your pet is having neurologic signs, inducing vomiting may result in aspiration pneumonia so we avoid this method of decontamination. This can be followed by activated charcoal, which can be helpful at preventing further absorption of the drug into the body. IV fluids are used to keep the pets hydrated and protect the organs, and this is especially important for our pets that are vomiting excessively.
One drug that is extremely helpful at reversing some of the signs of serotonin syndrome is the antihistamine Cyproheptadine. This drug is the most helpful in pets with restlessness and agitation in my experience. It can be given by mouth or rectally, so we can usually get it into all suspected patients. This medication is also a very safe thing to try if this syndrome is suspected (it won’t cause harm if clinical signs are not due to an antidepressant), and response to this therapy helps further support the diagnosis.
Sedatives are also helpful at controlling the clinical signs and allow our babies to get some needed rest in the ER. Cardiac medications can also be used if needed. I have rarely needed to use the seizure or cardiac medications in practice, and I usually only need to treat with cyproheptadine, IV fluids and maybe sedatives. As with most other neurotoxins the signs come on fast and are alarming, but they tend to resolve quickly with appropriate care and most pets make a full recovery within 12-24 hours.
What is the prognosis?
Prognosis depends on what agents were involved, the amount ingested, and the speed at initiating therapy. In my personal experience, I have found that the prognosis is generally very good, without any long lasting effects, as long as timely and appropriate care is initiated. Even though some cases can be mild, it is important to remember that this is an emergency situation and death can result in severe ingestions and even in small exposures if left untreated.
Prevention is the general theme with most toxin exposures, and I hope that this article has raised awareness with yet another potential hazard in our home.
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